| United States Patent Application |
20200340977
|
| Kind Code
|
A1
|
|
ADZHUBEI; Alexei
;   et al.
|
October 29, 2020
|
COMPOUNDS INHIBITING NEF-CALNEXIN INTERACTION
Abstract
The invention relates to compounds and methods for restoring or
preserving cholesterol efflux in a cell infected with Human
Immunodeficiency Virus (HIV) by preventing or decreasing an interaction
between Negative Regulatory Factor (Nef) protein and Calnexin protein,
and methods for screening for such compounds.
| Inventors: |
ADZHUBEI; Alexei; (Moscow, RU)
; BUKRINSKY; Michael; (Potomac, MD)
; HUNEGNAW; Ruth; (Arlington, VA)
|
| Applicant: | | Name | City | State | Country | Type | THE GEORGE WASHINGTON UNIVERSITY, A CONGRESSIONALLY CHARTERED NOT-FOR-PROFIT CORPORATION |
Washington | DC | US | | |
| Assignee: |
THE GEORGE WASHINGTON UNIVERSITY, A CONGRESSIONALLY CHARTERED NOT-FOR-PROFIT CORPORATION
Washington
DC
|
| Family ID:
|
59312145
|
| Appl. No.:
|
16/841444
|
| Filed:
|
April 6, 2020 |
Related U.S. Patent Documents
| | | | |
|
| Application Number | Filing Date | Patent Number | |
|---|
| | 16069483 | Jul 11, 2018 | 10684274 | |
| | PCT/US2017/013236 | Jan 12, 2017 | | |
| | 16841444 | | | |
| | 62277720 | Jan 12, 2016 | | |
|
|
| Current U.S. Class: |
1/1 |
| Current CPC Class: |
A61K 31/404 20130101; G01N 33/502 20130101; C07C 381/00 20130101; G01N 2333/163 20130101; A61K 31/167 20130101; G01N 33/5041 20130101; G01N 2333/4727 20130101; C07C 223/06 20130101; A61K 31/18 20130101; C07D 209/56 20130101; G01N 2500/02 20130101 |
| International Class: |
G01N 33/50 20060101 G01N033/50; A61K 31/18 20060101 A61K031/18; A61K 31/167 20060101 A61K031/167; A61K 31/404 20060101 A61K031/404; C07C 223/06 20060101 C07C223/06; C07C 381/00 20060101 C07C381/00; C07D 209/56 20060101 C07D209/56 |
Goverment Interests
FEDERAL FUNDING BY U.S. GOVERNMENT
[0002] This invention was made with Government support under Grant Nos.
R21 All 14471, R01 HL101274 and R21 AI108533 each awarded by The National
Institutes of Health (NIH). The U.S. Government has certain rights in the
invention.
Claims
1. A small molecule having the structure of Formula (II): ##STR00012##
wherein: R, R.sub.1, and R.sub.2 are independently selected from H,
CH.sub.2OH, COOH or COOCH.sub.3; and X is CH.sub.2, NH, O, NCH.sub.3, or
SO.sub.2.
2. A method for restoring or preserving cholesterol efflux in a cell
infected with Human Immunodeficiency Virus (HIV) comprising delivering to
the cell an effective amount of a composition or formulation comprising a
small molecule of Formula (II) or an analog or derivative thereof:
##STR00013## wherein: R, R.sub.1, and R.sub.2 are independently selected
from H, CH.sub.2OH, COOH or COOCH.sub.3; and X is CH.sub.2, NH, O,
NCH.sub.3, or SO.sub.2.
3. The method of claim 2, wherein the small molecule binds to at least
one amino acid residue on the Nef protein, wherein the at least one amino
acid residue is selected from the group consisting of a lysine at amino
acid position 4, a serine at amino acid position 6, a lysine at amino
acid position 7, and a tyrosine at amino acid position 124.
4. The method of claim 2, wherein the small molecule binds to at least
one amino acid residue on the Calnexin protein, wherein the at least one
amino acid residue is selected from the group consisting of an aspartic
acid at position 90, a glutamic acid at amino acid position 529, a
glutamic acid at amino acid position 532, and a glutamic acid at amino
acid position 533.
5. The method of claim 2, wherein preventing or decreasing the
interaction between the Nef protein and the Calnexin protein results in
at least partial restoration of ATP-Binding Cassette A1 (ABCA1) activity.
6. A method for treating or preventing atherosclerosis in a subject
infected with HIV comprising administering to said subject an effective
amount of a composition or formulation comprising a small molecule of
Formula (II): ##STR00014## wherein R, R.sub.1, and R.sub.2 are
independently selected from H, CH.sub.2OH, COOH or COOCH.sub.3; and X is
CH.sub.2, NH, O, NCH.sub.3, or SO.sub.2; and wherein the small molecule
prevents or decreases an interaction between a Nef protein and a Calnexin
protein.
7. The method of claim 6, wherein the small molecule binds to at least
one amino acid residue on the Nef protein, wherein the at least one amino
acid residue is selected from the group consisting of a lysine at amino
acid position 4, a serine at amino acid position 6, a lysine at amino
acid position 7, and a tyrosine at amino acid position 124.
8. The method of claim 6, wherein the small molecule binds to at least
one amino acid residue on the Calnexin protein, wherein the at least one
amino acid residue is selected from the group consisting of an aspartic
acid at position 90, a glutamic acid at amino acid position 529, a
glutamic acid at amino acid position 532, and a glutamic acid at amino
acid position 533.
9. The method of claim 6, wherein preventing or decreasing the
interaction between the Nef protein and the Calnexin protein results in
at least partial restoration of ATP-Binding Cassette A1 (ABCA1) activity.
10. A method for screening for a small molecule that restores or
preserves cholesterol efflux in a cell by inhibiting or decreasing an
interaction between a Nef protein and a Calnexin protein comprising:
incubating a cell expressing a full-length Nef protein or a segment of
the full-length Nef protein and a full-length Calnexin protein or a
segment of the full-length Calnexin protein with a small molecule of
interest; assaying the incubated cell for cholesterol efflux; and
assaying the incubated cell for a level of binding between the
full-length Nef protein or the segment of the full-length Nef protein and
the full-length Calnexin protein or the segment of the full-length
Calnexin protein, wherein an increase in cholesterol efflux and a
decrease in the level of binding as compared to a control is indicative
of restoration or preservation of cholesterol efflux by inhibiting or
decreasing an interaction between the Nef protein and the Calnexin
protein as a result of incubation of the cell with the small molecule of
interest.
11. The method of claim 10, further comprising virtually screening a
library of small molecules for a small molecule that is predicted to bind
to or interact with at least one of the full-length Nef protein or the
segment of the full-length Nef protein and the full-length Calnexin
protein or the segment of the full-length Calnexin protein.
12. The method of claim 10, wherein the cells are incubated for at least
1 day.
13. The method of claim 10, wherein the assaying the incubated cell for a
level of binding comprises an immunoprecipitation assay, surface plasmon
resonance (SPR) assay, or isothermal titration calorimetry (ITC) assay.
14. A small molecule having the structure of Formula (III): ##STR00015##
wherein: R is H, CH.sub.2OH, COOH or COOCH.sub.3; and X is CH.sub.2, NH,
O, NCH.sub.3, or SO.sub.2.
Description
CROSS-REFERENCE OF RELATED APPLICATION
[0001] This application is a Divisional Application of U.S. patent
application Ser. No. 16/069,483, filed on Jul. 11, 2018, which is a U.S.
National Stage Application under 35 U.S.C. .sctn. 371 of
PCT/US2017/013236, filed on Jan. 12, 2017, the entire content of which is
hereby incorporated by reference, and claims priority to U.S. Provisional
Application No. 62/277,720 filed Jan. 12, 2016; the entire contents of
all of which are hereby incorporated by reference.
BACKGROUND
1. Technical Field
[0003] The field of the currently claimed embodiments of this invention
relates to compounds and methods for restoring or preserving cholesterol
efflux in a cell infected with Human Immunodeficiency Virus (HIV) by
preventing or decreasing an interaction between Negative Regulatory
Factor (Nef) protein and Calnexin protein, and methods for screening for
such compounds.
2. Discussion of Related Art
[0004] Highly active anti-retroviral therapy (HAART) has transformed
treatment of the HIV disease changing prognosis from acutely lethal to
chronic illness, and lifespan of HIV-infected subjects approximates that
of uninfected individuals. However, HAART does not cure HIV, and chronic
HIV infection is associated with a number of co-morbidities, such as
premature atherosclerosis and cardio-vascular disease (37). An essential
component in pathogenesis of cardio-vascular disease in HIV-infected
subjects is HIV-associated dyslipidemia, which is caused both by drugs
used to treat HIV infection and by the effects of HIV itself on
cholesterol metabolism (38).
[0005] HIV-1 infection, via activity of viral protein Nef, impairs
cholesterol efflux mediated by the cholesterol transporter ATP-Binding
Cassette A1 (ABCA1) (1). ABCA1 is the main cellular cholesterol
transporter regulating delivery of cellular cholesterol to extracellular
acceptor, apolipoprotein A-I. Studies in animal models demonstrated that
this activity of Nef may be responsible for hypoalphalipoproteinemia and
high risk of atherosclerosis observed in HIV-infected subjects (2-4).
Recent studies identified calnexin, an integral endoplasmic reticulum
(ER) membrane lectin-like chaperone, as a key player in the mechanism of
Nef-mediated inhibition of ABCA1 and cholesterol efflux (5). Calnexin
(CNX) and its homologue calreticulin (CRT) regulate folding and
maturation of newly synthesized glycoproteins by engaging them in a
CNX/CRT cycle (6).
[0006] ABCA1 is a highly glycosylated protein (7). Although no evidence
for the role of CNX in ABCA1 biogenesis is available, two well-studied
ABC transporters, ABCC7 (also known as cystic fibrosis transmembrane
conductance regulator, CFTR) and ABCB1 (also known as multidrug
resistance protein 1 or P-glycoprotein 1), interact with CNX, and folding
mutants of these transporters are retained within the ER by CNX and
eventually degraded (8, 9). Importantly, ABCC7 and ABCB1 mutants that
escape CNX binding do not achieve mature glycosylation and these
mutations result in reduced transporter function (8, 9). A recently
published study demonstrated that ABCA1 interacts with CNX, and reduction
of CNX expression by RNAi resulted in a significant decrease in
functional activity of ABCA1, evidenced by reduced cholesterol efflux to
ABCA1-specific acceptor apoA-I (5). It was also shown that Nef impairs
interaction between ABCA1 and CNX, and this effect of Nef is essential
for inactivation and downregulation of ABCA1 (5). Importantly, inhibition
of ABCA1-calnexin interaction by Nef is specific, as interaction between
ABCA1 and two other proteins, dystrophin and serine palmitoyltransferase,
shown previously to bind ABCA1 (10), was not affected. Also not affected
was the interaction between calnexin and HIV-1 envelope glycoprotein,
gp160; in fact this interaction was even enhanced by Nef (5). These
findings suggested that Nef modulates activity of calnexin, but the
mechanism of this effect and molecular details of Nef/calnexin
interaction remained unknown. Moreover, it was unclear whether the
interaction between Nef and calnexin is direct, making screen for
inhibitory compounds difficult.
[0007] Calnexin is a 592-amino acid Type I transmembrane protein composed
of three parts: a lumenal fragment consisting of a globular n-sandwich
domain responsible for the interaction with carbohydrates and a
proline-rich tandem sequence repeat domain (the P domain) involved in
protein-protein interactions, a transmembrane domain, and a cytoplasmic
domain of 90 residues (11, 12). The cytoplasmic tail of calnexin can
undergo phosphorylation and palmitoylation which regulate calnexin
association with a number of proteins and protein complexes that
influence functional activity of this chaperone (13-18). For example,
palmitoylation of the C-tail of calnexin mediates its association with
the ribosome-translocon complex, which is essential for the ability of
calnexin to capture its client proteins as they emerge from the
translocon (18). Ribosome association of calnexin is also regulated by
phosphorylation on Ser534 and Ser544 by casein kinase 2 and on Ser563 by
protein kinase C/proline-directed kinase (11). In addition,
phosphorylation at Ser563 has been shown to play essential role in
quality control function of calnexin (15). Therefore, the C-tail of
calnexin may play a functional role regulating activity of the chaperone
both directly, by affecting ER lumenal events involving calnexin, and
indirectly, via modification of calnexin localization in the ER.
SUMMARY
[0008] An embodiment of the invention relates to a method for restoring or
preserving cholesterol efflux in a cell infected with Human
Immunodeficiency Virus (HIV) comprising delivering to the cell an
effective amount of a composition or formulation comprising a small
molecule. The small molecule prevents or decreases an interaction between
a Negative Regulatory Factor (Nef) protein and a Calnexin protein.
[0009] Another embodiment of the invention relates to a method for
treating or preventing atherosclerosis in a subject infected with HIV
comprising administering to said subject an effective amount of a
composition or formulation comprising a small molecule. The small
molecule prevents or decreases an interaction between a Nef protein and a
Calnexin protein.
[0010] Another embodiment of the invention relates to a method for
screening for a small molecule that restores or preserves cholesterol
efflux in a cell by inhibiting or decreasing an interaction between a Nef
protein and a Calnexin protein including: incubating a cell expressing a
full-length Nef protein or a segment of the full-length Nef protein and a
full-length Calnexin protein or a segment of the full-length Calnexin
protein with a small molecule of interest; assaying the incubated cell
for cholesterol efflux; and assaying the incubated cell for a level of
binding between the full-length Nef protein or the segment of the
full-length Nef protein and the full-length Calnexin protein or the
segment of the full-length Calnexin protein. In such embodiments, an
increase in cholesterol efflux and a decrease in the level of binding as
compared to a control is indicative of restoration or preservation of
cholesterol efflux by inhibiting or decreasing an interaction between the
Nef protein and the Calnexin protein as a result of incubation of the
cell with the small molecule of interest.
[0011] An embodiment of the invention relates to a small molecule having
the structure of Formula (I):
##STR00001##
[0012] Where R is H, CH.sub.2OH, COOH or COOCH.sub.3; X is CH.sub.2, NH,
O, NCH.sub.3, or SO.sub.2; and Y is a bond, CH.sub.2, CO or SO.sub.2.
[0013] An embodiment of the invention relates to a small molecule having
the structure of Formula (II):
##STR00002##
[0014] Where R, R.sub.1, and R.sub.2 are independently selected from H,
CH.sub.2OH, COOH or COOCH.sub.3; and X is CH.sub.2, NH, O, NCH.sub.3, or
SO.sub.2.
[0015] An embodiment of the invention relates to a small molecule having
the structure of Formula (III):
##STR00003##
[0016] Where R is H, CH.sub.2OH, COOH or COOCH.sub.3; and X is CH.sub.2,
NH, O, NCH.sub.3, or SO.sub.2.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Further objectives and advantages will become apparent from a
consideration of the description, drawings, and examples.
[0018] FIG. 1A shows a schematic of HA-tagged full-length and mutant
calnexin constructs expressed in HEK293T cells;
[0019] FIG. 1B is an immunoprecipitation assay showing expression of
HA-tagged full-length and mutant calnexin constructs HEK293T cells;
[0020] FIG. 2A shows representative models of Nef-CNX binding;
[0021] FIG. 2B shows interactions in Nef-CNX docking models mapped on Nef
and calnexin sequences;
[0022] FIG. 3A shows immunoprecipitation results comparing the interaction
between Nef Wild Type and Calnexin and NefK4,7A and Calnexin;
[0023] FIG. 3B shows immunoprecipitation results comparing the interaction
between Nef Wild Type and Calnexin and various Nef mutants and Calnexin;
[0024] FIG. 3C shows ABCA1 abundance as a function of mutations to Nef;
[0025] FIG. 3D shows NefK4,7A interaction with ABCA1 as compared to ABCA1
interaction with wild-type Nef;
[0026] FIG. 4A shows the effects of the mutation of certain residues on
Nef on regulation of ABCA1;
[0027] FIG. 4B shows the effects of the mutation of certain residues on
Nef on cholesterol efflux;
[0028] FIG. 5A shows the results of immunoprecipitation assays showing
that Nef directly binds to Calnexin and its cytoplasmic tail;
[0029] FIG. 5B is a graph mapping Nef binding to Calnexin and its
cytoplasmic tail;
[0030] FIG. 6A is a model showing where various small molecules disrupt
the Nef and calnexin interaction;
[0031] FIG. 6B shows the structures of various small molecules according
to some embodiments of the invention;
[0032] FIG. 6C is a graph showing the effects of various compounds on cell
metabolism as a function of the dose;
[0033] FIG. 6D is a blot and bar graph showing the effects of several
compounds ion Nef/CNX interaction;
[0034] FIG. 6E shows that the ABCA1/Nef interaction remains unaffected in
the presence of the indicated compound;
[0035] FIG. 7A is a box graph showing cholesterol efflux as a function of
treatment with various indicated compounds;
[0036] FIG. 7B is a graph showing a reduction in viral replication in
response to the presence of the indicated compound; and
[0037] FIG. 7C is a box graph showing that cholesterol efflux from
HIV-infected cells was decreased by 60%, whereas HIV-infected cells
treated with NSC 13987 showed cholesterol efflux not significantly
different from that of mock-infected cells.
DETAILED DESCRIPTION
[0038] Some embodiments of the current invention are discussed in detail
below. In describing embodiments, specific terminology is employed for
the sake of clarity. However, the invention is not intended to be limited
to the specific terminology so selected. A person skilled in the relevant
art will recognize that other equivalent components can be employed and
other methods developed without departing from the broad concepts of the
current invention. All references cited anywhere in this specification,
including the Background and Detailed Description sections, are
incorporated by reference as if each had been individually incorporated.
Definitions
[0039] The abbreviations used throughout are: ABCA1, ATP-binding cassette
A1; CNX, calnexin; CNX-CT, calnexin cytoplasmic tail; ER, endoplasmic
reticulum; HA, hemagglutinin; HIV-1, human immunodeficiency virus type 1;
HRP, horseradish peroxidase; PMA, phorbol-12-myristate 13-acetate; RT,
reverse transcriptase.
[0040] As used throughout the phrase an "effective amount" of a
composition of the invention is measured by the therapeutic effectiveness
of a compound of the invention, wherein at least one adverse effect of a
disorder is ameliorated or alleviated. More specifically, wherein
administering a compound or composition results in restoration or
preservation of cholesterol efflux in a cell or mammal infected with
Human Immunodeficiency Virus (HIV).
[0041] As used herein and unless otherwise indicated, the term
"formulation" refers to a composition comprising a compound of the
invention that is described in a particular dosage form (e.g., tablet) or
with a particular dosage amount (e.g., 30 mg/kg).
[0042] When administered to a subject (e.g., to an animal for veterinary
use or to a human for clinical use), the compounds of the invention can
be optionally administered in isolated form. As used herein, "isolated"
means that the compounds of the invention are separated from other
components of either (a) a natural source, such as a plant or cell,
preferably bacterial culture, or (b) a synthetic organic chemical
reaction mixture, preferably, via conventional techniques, the compounds
of the invention are purified. As used herein, "purified" means that when
isolated, the isolate contains at least 80% preferably at least 90%, more
preferably at least 95%, and most preferably at least 99% of a compound
of the invention by weight of the isolate.
[0043] The phrase "pharmaceutically acceptable salt(s)," as used herein
includes but is not limited to salts of acidic or basic groups that may
be present in compounds used in the present compositions. Compounds
included in the present compositions that are basic in nature are capable
of forming a wide variety of salts with various inorganic and organic
acids. The acids that may be used to prepare pharmaceutically acceptable
acid addition salts of such basic compounds are those that form non-toxic
acid addition salts, i.e., salts containing pharmacologically acceptable
anions including, but not limited to, sulfuric, citric, maleic, acetic,
oxalic, hydrochloride, hydrobromide, hydroiodide, nitrate, sulfate,
bisulfate, phosphate, acid phosphate, isonicotinate, acetate, lactate,
salicylate, citrate, acid citrate, tartrate, oleate, tannate,
pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate,
fumarate, gluconate, glucaronate, saccharate, formate, benzoate,
glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate,
p-toluenesulfonate and pamoate (i.e.,
1,1'-methylene-bis-(2-hydroxy-3-naphthoate)) salts. Compounds included in
the present compositions that include an amino moiety may form
pharmaceutically acceptable salts with various amino acids, in addition
to the acids mentioned above. Compounds, included in the present
compositions, that are acidic in nature are capable of forming base salts
with various pharmacologically acceptable cations. Examples of such salts
include alkali metal or alkaline earth metal salts and, particularly,
calcium, magnesium, sodium lithium, zinc, potassium, and iron salts.
[0044] As used herein and unless otherwise indicated, the term
"pharmaceutically acceptable prodrug" means a derivative of a compound
that can hydrolyze, oxidize, or otherwise react under biological
conditions (in vitro or in vivo) to provide the compound. Examples of
prodrugs include, but are not limited to, compounds that comprise
biohydrolyzable moieties such as biohydrolyzable amides, biohydrolyzable
esters, biohydrolyzable carbamates, biohydrolyzable carbonates,
biohydrolyzable ureides, and biohydrolyzable phosphate analogues. Other
examples of prodrugs include compounds that comprise oligonucleotides,
peptides, lipids, aliphatic and aromatic groups, or NO, NO.sub.2, ONO,
and ONO.sub.2 moieties. Prodrugs can typically be prepared using well
known methods, such as those described in Burger's Medicinal Chemistry
and Drug Discovery, pp. 172, 178, 949, 982 (Manfred E. Wolff ed., 5th ed.
1995), and Design of Prodrugs (H. Bundgaard ed., Elselvier, N.Y. 1985).
[0045] The terms "treating or preventing" are intended to include
preventing, eradicating, or inhibiting the resulting increase of
undesired physiological activity associated with a disorder, for example,
in the context of the therapeutic or prophylactic methods of the
invention. In another embodiment, the term treating or preventing
includes antagonistic effects, e.g., diminishment of the activity or
production of mediators of a disorder.
[0046] An embodiment of the invention relates to a method for restoring or
preserving cholesterol efflux in a cell infected with Human
Immunodeficiency Virus (HIV) comprising delivering to the cell an
effective amount of a composition or formulation comprising a small
molecule. The small molecule prevents or decreases an interaction between
a Negative Regulatory Factor (Nef) protein and a Calnexin protein.
[0047] Some embodiments of the invention relate to the method above, where
the small molecule binds to at least one amino acid residue on the Nef
protein. The at least one amino acid residue is selected from the group
consisting of a lysine at amino acid position 4, a serine at amino acid
position 6, a lysine at amino acid position 7, and a tyrosine at amino
acid position 124.
[0048] Some embodiments of the invention relate to the method above, where
the small molecule binds to at least one amino acid residue on the
Calnexin protein. The at least one amino acid residue is selected from
the group consisting of an aspartic acid at position 90, a glutamic acid
at amino acid position 529, a glutamic acid at amino acid position 532,
and a glutamic acid at amino acid position 533.
[0049] Some embodiments of the invention relate to the method above, where
preventing or decreasing the interaction between the Nef protein and the
Calnexin protein results in at least partial restoration of ATP-Binding
Cassette A1 (ABCA1) activity.
[0050] Some embodiments of the invention relate to the method above, where
the small molecule is a small molecule is selected from the group
consisting of Formula (I), Formula (II), Formula (III) or an analog or
derivative thereof:
##STR00004##
[0051] where R, R.sub.1, and R.sub.2 are independently selected from H,
CH.sub.2OH, COOH or COOCH.sub.3; X is CH.sub.2, NH, O, NCH.sub.3, or
SO.sub.2; and Y is a bond, CH.sub.2, CO or SO.sub.2.
[0052] Some embodiments of the invention relate to the method above, where
the small molecule is selected from the group consisting of Formula (IV),
Formula (V), Formula (VI) or an analog or derivative thereof:
##STR00005##
[0053] An embodiment of the invention relates to a method for treating or
preventing atherosclerosis in a subject infected with HIV comprising
administering to said subject an effective amount of a composition or
formulation comprising a small molecule. The small molecule prevents or
decreases an interaction between a Nef protein and a Calnexin protein.
[0054] Some embodiments of the invention relate to the method above, where
the small molecule binds to at least one amino acid residue on the Nef
protein. The at least one amino acid residue is selected from the group
consisting of a lysine at amino acid position 4, a serine at amino acid
position 6, a lysine at amino acid position 7, and a tyrosine at amino
acid position 124.
[0055] Some embodiments of the invention relate to the method above, where
the small molecule binds to at least one amino acid residue on the
Calnexin protein. The at least one amino acid residue is selected from
the group consisting of an aspartic acid at position 90, a glutamic acid
at amino acid position 529, a glutamic acid at amino acid position 532,
and a glutamic acid at amino acid position 533.
[0056] Some embodiments of the invention relate to the method above, where
preventing or decreasing the interaction between the Nef protein and the
Calnexin protein results in at least partial restoration of ATP-Binding
Cassette A1 (ABCA1) activity.
[0057] Some embodiments of the invention relate to the method above, where
the small molecule is a small molecule of Formula (I), Formula (II), or
Formula (III), or an analog or derivative thereof.
[0058] An embodiment of the invention relates to a method for screening
for a small molecule that restores or preserves cholesterol efflux in a
cell by inhibiting or decreasing an interaction between a Nef protein and
a Calnexin protein including: incubating a cell expressing a full-length
Nef protein or a segment of the full-length Nef protein and a full-length
Calnexin protein or a segment of the full-length Calnexin protein with a
small molecule of interest; assaying the incubated cell for cholesterol
efflux; and assaying the incubated cell for a level of binding between
the full-length Nef protein or the segment of the full-length Nef protein
and the full-length Calnexin protein or the segment of the full-length
Calnexin protein. In such embodiments, an increase in cholesterol efflux
and a decrease in the level of binding as compared to a control is
indicative of restoration or preservation of cholesterol efflux by
inhibiting or decreasing an interaction between the Nef protein and the
Calnexin protein as a result of incubation of the cell with the small
molecule of interest.
[0059] Some embodiments of the invention relate to the method above,
further including a step of virtually screening a library of small
molecules for a small molecule that is predicted to bind to or interact
with at least one of the full-length Nef protein or the segment of the
full-length Nef protein and the full-length Calnexin protein or the
segment of the full-length Calnexin protein.
[0060] Some embodiments of the invention relate to the method above, where
the cells are incubated for at least 1 day.
[0061] Some embodiments of the invention relate to the method above, where
the assaying the incubated cell for a level of binding comprises an
immunoprecipitation assay. In some embodiments, binding can be assayed
with recombinant Nef and calnexin proteins using Surface Plasmon
Resonance assay (Biacore) or Isothermal titration calorimetry.
[0062] An embodiment of the invention relates to a small molecule having
the structure of Formula (I):
##STR00006##
[0063] Where R is H, CH.sub.2OH, COOH or COOCH.sub.3; X is CH.sub.2, NH,
O, NCH.sub.3, or SO.sub.2; and Y is a bond, CH.sub.2, CO or SO.sub.2.
[0064] An embodiment of the invention relates to a small molecule having
the structure of Formula (II):
##STR00007##
[0065] Where R, R.sub.1, and R.sub.2 are independently selected from H,
CH.sub.2OH, COOH or COOCH.sub.3; and X is CH.sub.2, NH, O, NCH.sub.3, or
SO.sub.2.
[0066] An embodiment of the invention relates to a small molecule having
the structure of Formula (III):
##STR00008##
[0067] Where R is H, CH.sub.2OH, COOH or COOCH.sub.3; and X is CH.sub.2,
NH, O, NCH.sub.3, or SO.sub.2.
[0068] Some embodiments relate to combination therapeutic approaches where
any of the methods and/or compounds described are combined with at least
one other therapeutic agent or method for treating HIV. Common
therapeutic agents include, but are not limited to: Nucleotide reverse
transcriptase inhibitors; non-nucleotide RT inhibitors; integrate
inhibitors; fusion inhibitors; protease inhibitors; and CCR5 inhibitors.
[0069] Some embodiments are compounds derived from the compounds of
Formula (V). Such compounds include the compounds of Formulas (I), (II),
and (III), for example. Considerations taken into account when modifying
the chemical structure of Formula (V) to reach the chemical scaffolds of
Formulas (I), (II) and (III) included the removal of the two aromatic
rings and addition of functional groups that would improve the solubility
of Formula (V) derivatives in aqueous media. More specifically, in some
embodiments, the aromatic rings would be replaced with hydrophilic
moieties to promote solubility in aqueous media and promote binding to
Nef.
[0070] A first scaffold for Formula (V) derivatives includes changes to
the tetracyclic core (Anthraquinone derivatives) as shown in Formula (I):
##STR00009##
[0071] Where R is H, CH.sub.2OH, COOH or COOCH.sub.3; X is CH.sub.2, NH,
O, NCH.sub.3, or SO.sub.2; and Y is a bond, CH.sub.2, CO or SO.sub.2.
[0072] A second scaffold for Formula (V) derivatives includes changes to
the tricyclic core (Indole/sulfonylurea derivatives) as shown in Formulas
(II) and (III):
[0073] Formula (II):
##STR00010##
[0074] Where R, R.sub.1, and R.sub.2 are independently selected from H,
CH.sub.2OH, COOH or COOCH.sub.3; and X is CH.sub.2, NH, O, NCH.sub.3, or
SO.sub.2.
[0075] Formula (III):
##STR00011##
[0076] Where R is H, CH.sub.2OH, COOH or COOCH.sub.3; and X is CH.sub.2,
NH, O, NCH.sub.3, or SO.sub.2.
Example
[0077] In the following example, it is demonstrated that the C-tail of
calnexin is targeted by the HIV-1 protein Nef, which uses this
interaction to disrupt calnexin-assisted maturation of ABCA1 and impair
cholesterol efflux. Important structural features of the Nef/calnexin
interaction are characterized and a small molecule compound that blocks
this interaction and reverses negative effects of HIV infection on
cellular cholesterol metabolism is identified.
[0078] Results
[0079] Cytoplasmic Domain of Calnexin is Necessary for Interaction with
Nef
[0080] In a previous study it was shown that HIV-1 Nef interacts with the
ER chaperone calnexin (5). To test which region of calnexin is necessary
for binding to Nef, calnexin constructs that had deletion of the lumenal
repeat segment (aa 276-409) or truncation of the C-terminal cytoplasmic
domain (aa 504-586) (FIG. 1A). HEK293T cells were transfected with
Nef.sub.BRU-expressing vector and HA-tagged variants of wild-type (WT)
calnexin or the deletion mutants and performed co-immunoprecipitation.
FIG. 1B shows that WT calnexin interacted strongly with Nef, whereas
calnexin construct with internal repeat motif deletion
(CNX.sub..DELTA.276-409) exhibited binding reduced by 40%. However,
binding of Nef to calnexin construct carrying the truncation of the
C-terminal cytoplasmic tail (CMX.sub..DELTA.504-586) was reduced by 70%.
This finding highlights the importance of the cytoplasmic region of
calnexin in interaction with Nef. The role of calnexin cytoplasmic tail
in the interaction with Nef is consistent with Nef's localization to the
cytoplasm (19). Of note, the cytoplasmic domain of calnexin is composed
mainly of negatively charged amino acids, whereas the N-terminal region
of Nef is enriched in positively charged residues. The modest effect that
deletions in the lumenal repeat motif of calnexin have on Nef binding may
be due to conformational changes, which could affect all domains of
calnexin.
[0081] FIG. 1 shows a schematic of HA-tagged full-length and mutant
calnexin constructs expressed in HEK293T cells and immunoprecipitation
results of such constructs. Specifically, Panel (A) shows HA-tagged
full-length and mutant calnexin constructs expressed in HEK293T cells.
The various segments represented are the globular domain, tandem repeat
motif, TM domain and C-terminal cytoplasmic tail, respectively. Dropped
boxes represent deleted fragments. CNX.sub.WT represents full length
calnexin, CNX.sub..DELTA.486-567 has 81 out of the 89 cytoplasmic tail
residues deleted while maintaining the ER localization sequence RKPRRE;
CNX.sub..DELTA.257-388 construct has 131 residues of the P domain
deleted. In panel (B) HEK293T cells were co-transfected with Nef and
HA-tagged CNX.sub.WT, CNX.sub..DELTA.486-567 or CNX.sub..DELTA.257-388
vectors and blotted for HA, Nef and GAPDH (lysate). Calnexin variants
were immunoprecipitated 48 h post-transfection using anti-HA coupled
agarose beads and resulting immunoprecipitates were immunoblotted for Nef
(upper panel). Numbers under the lanes show relative amounts of
co-precipitated Nef obtained by gel densitometry.
[0082] Computational Model of Nef-CNX Interaction
[0083] Experimentally solved molecular structure of calnexin is available
only for the lumenal domain (12), and to obtain three-dimensional
structure of calnexin cytoplasmic domain a modeling with several modeling
servers implementing different methods was performed, which produced a
number of models ranging from the fully folded structures to structures
that included natively disordered regions. The models have been assessed
for accuracy and final round of modeling performed with the server
QA-RecombineIt. The final model had a loosely folded structure (FIG. 2A,
panel a). Computational prediction of Nef-CNX complexes showed Nef
N-terminal alpha-helix forming the interaction interface with calnexin
cytoplasmic domain (FIG. 2A, panels b and c).
[0084] In comparison with the calnexin cytoplasmic domain model, the model
of Nef was based on a number of experimental structures (20-24) and thus
had better accuracy. Nef-CNX interaction has been modeled by global
docking using four different docking servers, Cluspro, HEX, SwarmDock,
and Zdock. Combined set of the best Nef-CNX docking models produced with
these servers contained 80 models. The advantage of this approach is that
the resulting models represented Nef-CNX interaction modeled by four
different, unrelated methods and therefore it was more reliable than
using a single server. From these, 49 models have been filtered out as
possibly interfering with interaction of Nef with ER membrane.
Intermolecular interactions in the remaining subset of 31 models have
been identified. There are several distinct clusters of interactions,
with sharp maxima for Lys7 and Arg in positions 8, 19, 22, 75 and 109
(FIG. 2B). Notably, similar analysis of interactions carried out on the
full initial dataset of 80 docking models showed similar clustering and
maxima (not shown). It can therefore be hypothesized that the identified
residues represent the overall favorable Nef-CNX interaction sites. All
these residues, except Lys7 and Arg8, have been also identified as
participating in interactions in the experimental structures of complexes
which included Nef. A representative model of Nef-CNX binding is shown in
FIG. 2A, panels b and c. Analysis of the conserved residues in Nef
performed with ConSurf (25) revealed several such conserved positions in
the N-terminal region, including Lys4, Ser6, Lys7 and Arg19. Multiple
sequence alignment of the human HIV Nef sequences from Uniprot showed
that Lys7 is highly conserved across the spectrum of HIV-1 and HIV-2
sequences. Conserved residues indicate structurally and functionally
important positions, including interaction sites. Therefore, Lys7
represents a new interaction site which was not previously identified in
Nef interactions with other proteins.
[0085] FIG. 2 shows a schematic representation of Nef-CNX binding and the
interactions in Nef-CNX docking models mapped on Nef and calnexin
sequences. Specifically, panel (A) shows schematic representation of
Nef-CNX binding. (a) Schematic representation of the calnexin structure.
Lumenal domain is represented by the model structure; the transmembrane
region is shown as a helical domain according to the Uniprot (calnexin,
P27824) domain classification. Calnexin cytoplasmic domain and Nef are
represented by models built as described in Experimental Procedures, and
Nef/CNX binding is shown according to the results of docking. (b) Docking
model of the CNX cytoplasmic domain (green)--Nef (magenta) interaction.
The binding interface is formed by the Nef N-terminal alpha-helix, with
Lys 7 and Arg 8, 19, and 22 forming interactions with CNX. (c) Lys7 in
Nef (magenta) displays strong interaction with Glu533 in CNX (green)
formed by the hydrogen and ionic bonds. (d) Lys4 plays a key role in the
N-terminal region of Nef structure model (magenta). It forms a strong
intramolecular interaction with Nef Asp90 with hydrogen and ionic bonds,
supporting structural rigidity of the Nef N-terminal alpha-helix relative
to the rest of Nef structure. Panel (B) shows interactions in Nef-CNX
docking models mapped on Nef and calnexin sequences. Bars show the number
of interactions, with the numbers for each maximum showing sequence
number. In the Nef sequence, there are three distinct interaction
clusters centered on residues 7, 22, 75 and 109, with sharp maxima for
lysine 7, and arginines in positions 8, 19, 22, 75 and 109. Two
interaction clusters in the calnexin sequence are formed by amino acids
528-533 and 545-557; they include glutamic acid residues in positions
529, 532, 533.
[0086] Lysine Residues of Nef in Positions 4 and 7 are Critical for
Nef-CNX Interaction
[0087] According to docking modeling and sequence conservation results,
Lys7 possibly represents a new binding site in Nef and accordingly it has
been selected for mutagenesis experiments. Lys4 has been also selected
since it is a Lys7 near neighbor and, as demonstrated in the Nef model,
it plays a key structural role for the N-terminus (FIG. 2A, panel d).
Therefore, mutation of both Lys4 and Lys7 was predicted to invoke
structural rearrangement in the Nef N-terminal region thus disrupting the
interaction between Nef and calnexin. Alanine substitution of basic
residues at the N-terminus of Nef has previously been shown to preserve
membrane association and CD4 down-regulation by Nef (26), and
intracellular localization of the mutant Nef was indistinguishable from
that of Nef WT (27).
[0088] To verify the role of these residues in Nef interaction with
calnexin, the mutant HIV-1 NL4-3 clone carrying Nef with Lys4 and Lys7
changed to alanines was used. Calnexin was immunoprecipitated from
HEK293T cells transfected with WT or mutant HIV-1 clones and the
precipitate was immunoblotted for Nef. As shown in FIG. 3A, interaction
with calnexin was evident for Nef WT, but not for NefK4,7A. Interaction
with the double mutant was reduced by 95%, indicating that the lysine
residues in positions 4 and 7 are essential for Nef interaction with
calnexin.
[0089] In order to look at the individual contribution of the two lysine
residues to the interaction with calnexin, the Nef.sub.BRU plasmid was
mutagenized to create single and double lysine mutant constructs. HEK293T
cells were transfected with WT or mutant Nef constructs and the amount of
Nef found to immunoprecipitate with calnexin was analyzed again. Based on
densitometric analysis, interaction of CNX with NefK4A was reduced by 50%
whereas interaction with NefK7A was reduced by as much as 90% as compared
to interaction with WT Nef (FIG. 3B). Interaction of calnexin with
NefK4,7A was undetectable. This result was consistent with FIG. 3C, where
the expression of ABCA1 in the presence of single Nef mutants as compared
to the double lysine mutant was evaluated. NefK4A and NefK7A mutants
reduced ABCA1 abundance as much as the wild-type Nef, whereas near
control level of ABCA1 was observed when both lysine residues were
mutated (FIG. 3C). This result highlights the importance of both residues
in ABCA1 down-regulation, and suggests that even reduced interaction with
calnexin observed for NefK4A and NefK7A mutants is sufficient for ABCA1
downregulation.
[0090] To rule out the possibility that mutation of these residues grossly
affected the behavior of the N-terminal domain of Nef, the interaction of
the mutant Nef with ABCA1 was tested. Previous studies demonstrated that
interaction between Nef and ABCA1 also involves the N-terminal domain
(1), although the specific residues involved have not been identified.
Co-precipitation analysis revealed about a 30% reduction in NefK4,7A
interaction with ABCA1 as compared to ABCA1 interaction with wild-type
Nef (FIG. 3D). The reduction, however, remains in stark contrast to the
>95% loss of interaction observed in the Nef-CNX interaction studies
(FIG. 3A).
[0091] Functional Analysis of Nef Mutants
[0092] In a previous study, it was reported that Nef plays a central role
in the down-modulation of ABCA1 expression and function (1). This
phenotype was associated with Nef's ability to interact with calnexin and
disrupt calnexin interaction with ABCA1 (5). Identification of Nef
residues required for interaction with calnexin provided an opportunity
to verify the critical role of this interaction for the effects of Nef on
cellular cholesterol metabolism. To assess the functional consequence of
losing the Nef/CNX interaction for ABCA1 functionality, HEK293T cells
were co-transfected with ABCA1 and HIV-1 NL4-3 infectious clones that
express either Nef WT or Nef K4,7A. Lysates were immunoblotted for ABCA1
(FIG. 4A). Consistent with results obtained with Nef-expressing vector
(FIG. 3C), total ABCA1 abundance was significantly reduced in the
presence of Nef WT, however, expression of ABCA1 in the presence of Nef
K4,7A was comparable to that of the control sample, which was transfected
with an empty vector. This result is consistent with conclusions of the
previous study that identified Nef as the key viral factor responsible
for ABCA1 downregulation (1).
[0093] FIG. 3 shows various immunoprecipitation results displaying the
interaction between Nef and Calnexin as a result of various conditions.
Specifically, Panel A shows HEK293T cells transfected with HIV-1
molecular clones encoding for Nef WT or Nef K4,7A. Panel B shows HEK293T
cells transfected with pcDNA plasmids expressing Nef WT or mutants Nef
K4A, Nef K7A or NefK4,7A. Cells were lysed 48 h post-transfection.
Endogenous calnexin was immunoprecipitated using monoclonal calnexin
antibody and immunoprecipitates were blotted for Nef and calnexin (top
panels). Whole cell lysates were analyzed for expression of calnexin
(CNX), Nef and GAPDH (bottom panels). In panel (C), HEK293T cells were
co-transfected with ABCA1-FLAG and Nef WT or mutants Nef K4A, Nef K7A or
Nef K4,7A. Cells were lysed 48 h post-transfection and lysates were
analyzed for expression of ABCA1, Nef and GAPDH. In panel (D) HEK293T
cells were co-transfected with ABCA1-FLAG and Nef WT or NefK4,7A and were
lysed 48 h post-transfection. ABCA1 was immunoprecipitated using
anti-FLAG beads and precipitates were blotted for ABCA1 and Nef (top
panel). Whole cell lysates were analyzed for expression of ABCA1-FLAG,
Nef and GAPDH (bottom panel). Numbers under the lanes show relative
amounts of co-precipitated Nef obtained by gel densitometry.
[0094] The effect of mutations disrupting Nef/CNX interaction on the
ability of Nef to downregulate apoA-1 specific cholesterol efflux was
evaluated. Monocyte derived macrophages were infected with HIV-1
expressing either wild-type Nef or Nef K4,7A. Given that the virus
carrying the mutation was the X4-tropic strain NL4-3, it was pseudotyped
with VSV-G to ensure one-cycle infection. Seven days after infection,
cholesterol efflux assay was performed. In agreement with previous
reports (1, 5, 28), cells infected with the wild-type virus had
significantly reduced cholesterol efflux relative to mock-infected cells
(FIG. 4B). However, infection with the virus carrying Nef K4,7A did not
lead to efflux decrease.
[0095] FIG. 4 shows various assays showing the effects of the mutation of
certain residues on Nef on regulation of ABCA1 and cholesterol efflux.
Specifically, in panel (A) HEK 293T cells were co-transfected with ABCA1
and HIV-1 molecular clones encoding Nef WT or Nef K4,7A (HIV-1 clone with
a Nef deletion was used as control). Cells were lysed 48 h
post-transfection and immunoblotted for ABCA1, Nef and GAPDH. In panel
(B), THP-1 cells were infected with HIV-1 molecular clones pseudotyped
with VSV-G consisting of a Nef deletion (.DELTA.Nef) or expressing Nef WT
or mutant Nef K4,7A. Cholesterol efflux was measured 13 days after
infection. Results show apoA-I specific cholesterol efflux as mean.+-.SEM
of quadruplicates. Western blot shows expression of Nef in cell lysates.
[0096] Interaction Between Nef and Calnexin is Direct
[0097] To test whether Nef and calnexin interact directly with each other,
CNX and the cytoplasmic tail of CNX (CNX-CT) was expressed in E. coli and
purified recombinant proteins by column chromatography. For purification
of full-length calnexin, a novel purification system based on the
ultra-high affinity (K.sub.d.about.10.sup.-14-10.sup.-17M) small protein
complex of genetically inactivated colicin 7 DNAse (CL7) and its
inhibitor, immunity protein 7 (Im7) (29-32) was developed and
implemented. A CL7 variant, which possesses no DNAse activity but retains
full Im7 affinity, was attached as a C-terminal tag on His-tagged
calnexin construct (FIG. 5A, left side). A cleavage site for the
pre-scission protease (PSC) inserted between CNX and CL7 allowed for
elution of CNX from the Im7 column through cleavage by PSC. A single
purification step provided an excellent yield of .about.90% pure protein
(FIG. 5A), in which major contamination represented CNX molecules
(confirmed by mass-spec), most likely, truncated from the N-terminus. The
CNX-CT construct was designed with a single N-terminal His-tag and was
purified using the standard procedure (FIG. 5A, right side).
[0098] Binding of myristoylated Nef.sub.SF2 (33) to CNX and its
cytoplasmic domain was analyzed using surface plasmon resonance (FIGS.
5B,C). CNX and CNX-CT were immobilized on microchip surfaces and
myristoylated Nef was injected over the surface. Nef.sub.SF2 directly
bound to calnexin with an affinity (K.sub.D) of 89.1 nM (k.sub.a=1.338E5
M.sup.-1s.sup.-1, k.sub.d=0.01192 s.sup.-1, Chi.sup.2=2.77 RU) (FIG. 5B).
Binding to CNX-CT was observed to have higher affinity of K.sub.D=9.4 nM
(k.sub.a=9.083E5 M.sup.-1 s.sup.-1, k.sub.d=0.008569 s.sup.-1,
Chi.sup.2=0.474 RU) (FIG. 5C). Taken together, these experiments
demonstrate that Nef/CNX interaction is direct and involves the
cytoplasmic domain of calnexin.
[0099] FIG. 5 shows the results of immunoprecipitation assays showing that
Nef directly binds to Calnexin and its cytoplasmic tail. Specifically,
panel (A) shows purification of CNX and CNX-CT. Steps of full-length
CL7-tagged calnexin (CNX-CL7) purification are shown in detail. Whole
cell lysate (WCL) was centrifuged to remove cell debris, the supernatant
(SN) was treated with 0.07% polyethylene-emine (PE) to precipitate DNA,
the pellet (PL), which contained most of CNX protein, was washed with
detergent-containing buffer to release CNX into solution, centrifuged and
the resulting supernatant was loaded on Immunity protein 7 (Im7) column.
Bound proteins were eluted by treating the column with pre-scission
protease (PSC) (EL lane), whereas flow-through (FT) lane shows unbound
proteins. .DELTA.CNX--truncated CNX fragment; SUMO--SUMO domain; P(PSC),
P(SUMOP)--cleavage sites for the PSC and SUMO proteases, respectively;
H8--8-Histidine tag. In panels (B) and (C), surface plasmon resonance
experiments were done in a Biacore T-200 by using a CM5 chip. Panel (B)
shows CNX and Panel (C) shows CNX-CT proteins captured by amine coupling
and myristoylated Nef.sub.SF2 protein injected over the chip surface at 6
different concentrations (6.25 nM-200 nM range) in triplicates. Lines
representing actual data and a curve fit to a monovalent analyte binding
model in BiaEvaluation software are shown.
[0100] Virtual Screening for Compounds Interfering with Nef/CNX
Interaction
[0101] Docking-based virtual screening has been performed on compounds
from the Zinc NCI Plated 2007 dataset with docking program Vina (34). Nef
model described in FIG. 2 has been used, with the interaction site for
ligand docking selected to cover amino acid residues Lys4 and Lys7. The
dataset consisted of 139,735 compounds. Ten putative ligands were
identified and prioritized according to the Vina ranking, and structural
alignment of these compounds to the Nef-CNX complex is shown in FIG. 6A
(panel a). The model shows that these compounds can block Nef/CNX
interaction at the CNX residues Glu529, Glu532 and Glu533. Docking of NSC
13987, which turned out in the later studies to be the most effective
inhibitor of the Nef-CNX interaction, is shown in panel b (FIG. 6A).
Interactions of the compound with Nef include two hydrogen bonds with Nef
amino acid residues Ser6 and Tyr124. Three of the 10 compounds, NSC 1758,
NSC 13987, and NSC 92938 have been submitted for experimental testing.
The chemical names and molecular structures of these compounds are shown
in FIG. 6B.
[0102] Testing the Compounds' Activity
[0103] To test whether the compounds identified in the virtual screen can
interfere with Nef/CNX interaction, a co-immunoprecipitation assay was
performed. HEK293T cells were transfected with plasmid encoding for
Nef.sub.BRU and 6 h post-transfection were treated with NSC 1758 (4
.mu.M), NSC 13987 (5 .mu.M), or NSC 92938 (5 .mu.M). These concentrations
of the compounds were determined by the MTT assay to reduce cell
metabolism by less than 10% during 5-day incubation (FIG. 6C). Among the
3 compounds tested, one compound, NSC 13987, inhibited
co-immunoprecipitation of Nef and calnexin by over 50%, whereas the
effect of NSC 1758 and NSC 92938 showed a trend towards inhibiting
Nef/CNX binding but did not reach statistical significance (FIG. 6D). It
was previously shown that membrane localization of Nef is important for
interaction of Nef with calnexin (5). In order to rule out the
possibility that the compound interferes with membrane localization of
Nef, it was tested whether NSC 13987 affects interaction between Nef and
ABCA1, as ABCA1/Nef interaction also requires membrane localization of
Nef (1). As shown in FIG. 6E, ABCA1/Nef interaction remained unaffected
in the presence of compound indicating that the inhibition was specific
to the molecular interaction of Nef and CNX.
[0104] FIG. 6 shows the structures of various small molecules targeting
the Nef-Calnexin interaction as well as the effects these molecules have
on the Nef-Calnexin. Specifically, panel (A) a, shows the results of ten
compounds with the best score (grey) from virtual screening performed on
the Zinc NCI Plated 2007 dataset. Their overall location in the
structural alignment with the model of Nef--CNX complex is shown as
translucent molecular surface. The model shows that these compounds can
block the Nef/CNX interaction at calnexin residues Glu529, Glu532 and
Glu533. The set of compounds includes NSC 1758, NSC 13987, and NSC 92938
selected for experimental testing. b, Compound NSC 13987 docked to Nef
binding site, which is centered on Lys4 and Lys7. Interactions of the
compound with Nef include two hydrogen bonds with Nef amino acid residues
Ser6 and Tyr124. Panel (B) shows the chemical structure and name of
compounds NSC 1758, NSC 13987, and NSC 92938. Panel (C) shows the
dose-response effect of NSC 1758, NSC 13987 and NSC 92938 on viability of
THP-1 cells. THP-1 cells were treated with indicated compounds for 5 days
and cytotoxicity was measured using MTT assay. In panel (D), HEK 293T
cells were transfected with HA-tagged Nef, treated with compounds NSC
1758, NSC 13987 or NSC 92938, and lysed. Nef was immunoprecipitated using
anti-HA agarose beads and bound complexes were immunoblotted for Nef and
calnexin (left panels labeled IP: .alpha.HA). Densitometric
quantification of calnexin co-immunoprecipitation with Nef is presented
in the right panel. Error bars indicate +/-SD of 3 independent
experiments, and p values are shown above the bars. Whole cell lysates
were analyzed for amount of calnexin, Nef and GAPDH (left panels labeled
Lysate). In panel (E), HEK293T cells were co-transfected with ABCA1-FLAG
and Nef.sub.BRU and treated with compound NSC 13987. Cells were lysed 48
h post-transfection and ABCA1-FLAG was immunoprecipitated using anti-FLAG
beads. Precipitated complexes were blotted for ABCA1 and Nef (top
panels). Input amount was analyzed from whole cell lysates by
immunoblotting for ABCA1, Nef and GAPDH (bottom panels).
[0105] Next, it was tested whether the three compounds could prevent
impairment of cholesterol efflux by Nef. THP-1 cells were transfected
with a Nef encoding plasmid and drug treatment was started 6 h after
transfection. The following day cells were activated with PMA after which
cholesterol efflux assay was performed. Drug treatment was continued
throughout the duration of the experiment. FIG. 7A shows cholesterol
efflux measured in untreated cells or cells treated with DMSO or each of
the 3 compounds. Cholesterol efflux in Nef-transfected untreated or
DMSO-treated cells was reduced by over 2-fold relative to
mock-transfected cells. NSC 13987, which showed inhibition of Nef/CNX
interaction (FIG. 6D), significantly increased cholesterol efflux as
compared to DMSO-treated Nef expressing cells, although the rescue was
not complete. Two other compounds did not significantly rescue
Nef-suppressed cholesterol efflux.
[0106] To test the effect of NSC 13987 in the context of natural
infection, monocyte-derived macrophages (MDM) were infected with HIV-1
ADA, treated with NSC 13987 and cholesterol efflux was measured. Viral
replication in the presence of the compound was reduced (FIG. 7B),
consistent with demonstrated rescue by the compound of Nef-inhibited
cholesterol efflux (FIG. 7A) and previous studies demonstrating anti-HIV
activity of ABCA1 and ABCA1-stimulated cholesterol efflux (28, 35, 36).
Consistent with previous studies (1, 5, 36), cholesterol efflux from
HIV-infected cells was decreased by 60%, whereas HIV-infected cells
treated with NSC 13987 showed cholesterol efflux not significantly
different from that of mock-infected cells (FIG. 7C). Taken together,
these results provide a proof of concept for the idea that HIV-induced
impairment of cholesterol efflux can be reversed pharmacologically by
blocking the Nef/CNX interaction.
[0107] FIG. 7 shows graphs showing that an embodiment of the invention,
compound NSC 13987, prevents impairment of cholesterol efflux by HIV and
Nef. Specifically, in panel (A) THP-1 cells were transfected with Nef and
incubated with compounds NSC 1758, NSC 13987 and NSC 92938 or DMSO, and
cholesterol efflux was measured 5 days post-transfection. Error bars show
SEM. In panel (B) primary macrophages were infected in triplicate with
HIV-1 ADA. Compound NSC 13987 (5 .mu.M) or DMSO was added 3 days after
infection and maintained thereafter, and virus replication was monitored
by measuring RT-activity in the supernatant over a 14-day period. Results
of 3 measurements are shown as mean.+-.SEM. *, p<0.005; **,
p<0.007. In panel (C) primary macrophages were infected with HIV-1 ADA
or mock-infected and treated with DMSO or NSC13987 as in panel B.
Cholesterol efflux was measured 14 days post-infection. Error bars show
SEM.
[0108] Discussion
[0109] In this example, a small-molecule compound that blocks HIV-mediated
impairment of cellular cholesterol metabolism was identified. Excitingly,
this compound also inhibited replication of HIV, suggesting that, if
developed into a drug, it can target both HIV infection and virus-induced
metabolic co-morbidities.
[0110] Previous studies demonstrated that HIV critically depends on
interaction with host cholesterol metabolism and modifies it for
optimization of viral replication (1, 2, 28, 35, 36). Specifically, HIV,
through viral protein Nef, reduces abundance and impairs functional
activity of ABCA1, a key transporter in cholesterol efflux pathway (1).
As a result, host cells accumulate excessive cholesterol promoting
formation of plasma membrane lipid rafts, which are sites of HIV entry,
assembly and budding (39). Recently, it was demonstrated that an
important mechanism of down-regulation and/or functional impairment of
ABCA1 by HIV is Nef-mediated inhibition of the interaction between ABCA1
and the ER chaperone, calnexin (5). The current study provides the first
characterization of the exact molecular structures involved in Nef-CNX
interaction.
[0111] First, it was established that interaction between Nef and calnexin
involves the cytoplasmic domain of calnexin. While this finding is
consistent with demonstrated localization of Nef to the cytoplasmic side
of membranes (27) and lack of evidence for Nef localization to ER, it is
surprising given that the C-tail of calnexin is not involved in the
interaction between calnexin and ABCA1, which is disrupted by Nef (5).
Indeed, calnexin interactions with glycosylated proteins are mediated by
its lumenal domains (12). Therefore, Nef interaction with the C-tail
alters activity of the lumenal domains of calnexin. How Nef is doing it
is unknown and several possibilities can be considered. Binding of Nef
may prevent post-translational modifications of the C-tail of calnexin,
such as phosphorylation on Ser563 that has been shown to regulate
calnexin interaction with al-antitrypsin and a number of other
glycoproteins (15). However, docking analysis did not reveal Ser563 as a
likely site for interaction with Nef (FIG. 5B). The same argument can be
applied to SUMOylation at Lys506, which has been shown to regulate
calnexin interaction with another ER protein, protein tyrosine
phosphatase 1B (40): Lys506 is not among the preferred sites for Nef
binding. It is possible that Nef binding itself induces a conformational
change in calnexin extending to its lumenal domains, but mechanistic
details of such an effect await careful structural analysis. Regardless
of the mechanism, this finding provides the first example of a pathogen
utilizing the calnexin C-tail to regulate functional activity of this
chaperone.
[0112] Second, the Nef residues critical for interaction with calnexin
were identified: mutation of lysine residues in positions 4 and 7 of Nef
abrogated Nef/CNX binding, prevented ABCA1 downregulation, and restored
cholesterol efflux in cells infected with HIV-1. The finding that Nef/CNX
interaction involves the flexible N-terminal region of Nef was
surprising, as this region has not been implicated before in
protein-protein interactions. However, molecular modeling (FIG. 2)
suggests that Lys4 of Nef forms a hydrogen bond with Asp90 located in an
alpha-helix, thus contributing to stabilization of the structure of the
N-terminal region, and therefore acts as a structural anchor for the Nef
Lys7 interaction with calnexin. Nef Lys7 is predicted to form a strong
interaction with Glu533 in calnexin through the hydrogen and ionic bonds.
Thus, mutation of both lysine residues destabilizes the structure of Nef,
and cancels the strong interaction with calnexin provided by Lys7, which
explains the dramatic effect of these mutations on Nef/CNX interaction.
The N-terminal region of Nef has not been involved in protein-protein
interactions, but its basic and hydrophobic residues were shown to be
essential for membrane association of Nef (41). Interestingly, lysine
residues at positions 4 and 7, which participate in interaction with
calnexin, were not essential for the membrane association of Nef (42).
Therefore, this study a novel epitope on Nef involved in the interaction
with the cytoplasmic tail of calnexin was identified.
[0113] Using this information, a virtual screening for compounds that can
potentially disrupt Nef-CNX interaction was performed, and a number of
candidates were identified. One of these compounds,
1[(7-Oxo-7H-benz[de]anthracene-3-yl)amino]anthraquinone (NSC 13987),
prevented co-precipitation of CNX with Nef, reversed Nef-mediated effect
on ABCA1 abundance, and restored cholesterol efflux impaired by Nef, thus
effectively reversing the effects of Nef on host cholesterol metabolism.
In addition, the compound resulted in a near 2-fold inhibition of viral
replication (FIG. 7B). This latter effect may have two main explanations.
First, the compound prevents ABCA1 downregulation by Nef, and ABCA1 has
been shown to inhibit HIV-1 replication by reducing lipid rafts abundance
on the plasma membrane and affecting production and infectivity of
nascent virions (3, 28, 35, 36). Second, previous reports presented
evidence that anthraquinone derivatives inhibit the ribonuclease H
function of HIV-1 reverse transcriptase (43, 44). These findings provide
basis for using NSC 13987 as a foundation for development of novel
treatment approaches based on targeting the interaction of HIV with host
cholesterol metabolism. Based on the known effects of OCR agonists, it is
unlikely that this approach would generate a stand-alone treatment for
HIV. However, it may effectively supplement current treatment regimens
significantly increasing their efficiency and/or allowing for reduction
of doses. Furthermore, the effects of Nef secreted from HIV-infected
cells may be responsible for many lipid-related complications of HIV
disease, such as atherosclerosis, diabetes, lipodistrophy and
neurodegeneration. The approach proposed in this study will also reverse
HIV-induced impairment of cholesterol metabolism in uninfected cells
mitigating lipid-related complications of HIV infection in addition to
contributing to the treatment of HIV itself.
[0114] Calnexin is an ER-integral membrane protein and is responsible for
the folding of several glycoproteins. Depletion of calnexin has been
shown to result in the elevation of several other ER-folding factors
minimizing aberrant protein folding and expression (45). This is mainly
true for glycoproteins which are common substrates of other soluble ER
chaperones like calreticulin. However, solubility and oligosaccharide
variability impose a limit on this commonality making calnexin vital for
expression and function of proteins like ABCA1 and several others (5, 46,
47). Nef's ability to target several host factors, such as CD4, MHC I,
CXCR4, may in part be due to the limitation it imposes on their access to
chaperone proteins like calnexin. Therefore, the positive effect of
compound NSC13987 may well extend to restoring the expression and
function of other proteins targeted by Nef.
[0115] In conclusion, in this study the molecular mechanisms and exact
structures involved in interaction between HIV Nef and host canexin were
identified and a compound capable of reversing the effects of Nef was
characterized, thus presenting potential utility in treatment of HIV
infection and its metabolic side effects.
[0116] Experimental Procedures
[0117] Reagents--The following reagents were purchased from the indicated
suppliers: mouse monoclonal anti-calnexin (ab31290, Abcam); anti-HA
Epitope tag Antibody (NB600-363, Novus Biologicals); anti-Nef serum (NIH
AIDS Reagent Program); anti-ABCA1 (NB400-105, Novus Biologicals);
polyclonal rabbit anti-calnexin (H-70, Santa Cruz Biotech); anti-GAPDH
(G9545, Sigma Aldrich); HRP conjugated donkey anti-rabbit and Goat
anti-mouse (Jackson Immuno Research); anti-HA Agarose (26181, Thermo
Scientific); EZview Red Protein A Affinity Gel (P6486, Sigma-Aldrich).
Metafectene.RTM. (Biontex; IGEPAL (CA-630, SigmaAldrich); Triton.TM.
(X-100, Sigma Aldrich); 10% SDS (Corning).
[0118] Nef and Calnexin Mutagenesis--Nef expression plasmid pcDNA3.1 Nef
was obtained through the NIH AIDS Reagent Program (Cat#11431) from Dr. J.
Victor Garcia. The Nef insert was cloned by PCR using primers as
previously described (48) and was mutagenized. Nef mutants K4A, K7A and
K4,7A were generated from the pcDNA3.1 Nef.sub.BRU plasmid using
site-directed mutagenesis with Pfu Ultra High-Fidelity DNA Polymerase
(Agilent Technologies). Forward and reverse primer sequences used were as
follows: Nef K4A Fwd, 5'-TTTGCTATAAGATGGGTGGCGCGTGGTCAAAAAGTAGTGTGG-3',
Rev 5'-CCACACTACTTTTTGACCACGCGCCACCCATCTTATAGCAAA-3'; Nef K7A Fwd,
5'GATGGGTGGCAAGTGGTCAGCAAGTAGTGTGGTTGGATGG-3', Rev
5'-CCATCCAACCACACTACTTGCTGACCACTTGCCACCCATC-3 and NefK4,7A FWD
5'-GGGTGGCGCGTGGTCAGCAAGTAGTGTGGTTGGA-3', Rev
5'-TCCAACCACACTACTTGCTGACCACGCGCCACCC-3'. Resulting cDNA was transformed
into XL10-Gold Ultracompetent Cells and final plasmid preps were
sequenced to confirm mutations. The plasmid pCG-NL4-3-IRES-GFP was kindly
provided by the lab of Dr. Marc Harris (27).
[0119] Human CNX cDNA construct with a C-terminal HA tag was prepared by
standard PCR method from CNX cDNA clone (Open Biosystems) in the pHCMV3
vector (Gelantis). Truncated CNX construct was generated similarly by
using primers described previously (49). The HA-tagged
CNX.sub..DELTA.504-586 construct lacks the 87 residues of the cytoplasmic
tail. Deletion of the repeated sequence motifs referred to as
CNX.sub..DELTA.276-409 was made by restriction digest of full length
HA-tagged pHCMV3-CNX and re-ligation (46).
[0120] Expression and Purification of Calnexin--
[0121] A CNX expression vector with a His-tag at the N-terminus and the
CL7-tag was designed, which can be cleaved by the PSC protease, at the
CNX C-terminus (FIG. 5A). The CNX-CT construct was designed with a single
N-terminal His-tag followed by the SUMO-domain (to allow His-tag cleavage
by the SUMO-protease, SUMO-P). CNX and CNX-CT were expressed in E. coli
BL21 DE. Cells were grown at 37.degree. C. to OD.about.0.8-0.9, then
temperature was decreased to 18-20.degree. C. and expression was induced
with 0.1 mM IPTG overnight. Cells were frozen at -80.degree. C. until
protein purification.
[0122] A novel purification system based on the natural ultra-high
affinity complex (K.sub.m.about.10.sup.-14-10.sup.-17 M) between the
colicin E7 DNAse domain (CL7) and its inhibitor, immunity protein 7 (Im7)
(29-32) was developed and implemented. The proteins have been modified to
remove DNAse activity of CL7 and allow for efficient immobilization of
the Im7 unit on the activated agarose beads (DGV, unpublished results).
The CNX construct tagged at the C-terminus with CL7 was expressed in E.
coli, the cells were lysed, centrifuged to remove cell debris, and the
supernatant was treated with 0.07% polyethylene-emine (PE) to precipitate
CNX (FIG. 5A). The pellet was washed with 20 mM Tris-HCl, pH 8.0, 600 mM
NaCl, 1.5% dodecyl-maltopyranoside to release CNX into solution,
centrifuged again, and the resulting supernatant was loaded on the Im7
column. CNX protein was eluted from the column upon treatment by PSC
protease. This single purification step provided an excellent yield of
.about.90-95% pure protein, in which major contamination represents
truncated CNX molecules (confirmed by mass-spectroscopy). Given that
these molecules are retained on the column and that affinity tag is
localized at the C-terminus of CNX, truncation occurred most likely from
the N-terminus (proteolytic sensitivity of CNX at the N-end was reported
previously (50)). CNX-CT was purified in standard procedure using the
commercial His-Trap column. All procedures were carried out at 4.degree.
C.
[0123] Surface Plasmon Resonance Experiments--
[0124] Direct binding between purified recombinant proteins was evaluated
by surface plasmon resonance technology utilizing a Biacore T-200
instrument at the Biacore Molecular Interaction Shared Resource of
Georgetown University. Full length CNX and the C-terminal (cytoplasmic)
domain of CNX (CNX-CT) were captured on CM5 chips by amine coupling.
Three surfaces of CM5 chip were activated by NHS/CDC
(N-hydroxysuccinimide/1-ethyl-3-(3-dimethylaminopropyl)carbodiimide
hydrochloride) for 720 sec. Flow cell 1 was left empty as a reference
surface. Full length CNX and CNX-CT were diluted in 10 mM sodium acetate
(pH 4.0) buffer at 1.8 .mu.M and 10.6 .mu.M, respectively, and captured
on flow cell 3 and flow cell 2, at 3200 RU and 16600 RU, respectively.
After protein capture, all 3 flow cells were inactivated by 720 sec
injection of 1 M ethanolamine. Myristoylated Nef.sub.SF2 protein was
injected over the chip surface at 6 different concentrations (6.25 nM,
12.5 nM, 25 nM, 50 nM, 100 nM, 200 nM) in triplicates. All binding
studies were done at 25.degree. C. Flow rate for protein capture was 10
.mu.l/min, and kinetics experiment was at 50 .mu.l/min. HPS-P (10 mM
HEPES pH 7.4, 150 mM NaCl, 0.005% surfactant P-20)+2 mM CaCl.sub.2 was
used as the running buffer. The data was analyzed by BiaEvaluation
software using the bivalent analyte model.
[0125] Cells and Transfection--
[0126] HEK293T and THP-1 cells were cultured in RPMI supplemented with 10%
fetal bovine serum and antibiotics. For transfection, 293T cells were
passaged and cultured overnight in 6-well plates and transfected with
plasmid DNA using Metafectene according to the manufacturer's (Biontex)
instructions.
[0127] Compounds--
[0128] Three out of 10 compounds obtained from NCI drug database were
tested for blocking Nef/CNX interaction. Tested compounds were
1,3-DI-9-Phenanthrylguanidine (NSC 1758),
1[(7-Oxo-7H-benz[de]anthracene-3-yl)amino]anthraquinone (NSC 13987) and
5H-Naphtho(2,3-a)carbazole-5,13(12H)-dione (NSC 92938). All compounds
were dissolved in DMSO and diluted in cell culture medium (RPMI 1640 with
10% fetal bovine serum and antibiotics) to ensure the final concentration
of the solvent to be <1%.
[0129] MTT Assay--
[0130] THP-1 cells were seeded in 96 well plates (30,000 cells/well) and
incubated at 37.degree. C., 5% CO.sub.2 in the presence of compounds for
5 days. The MTT assay for cytotoxicity was done in quadruplicates
according to manufacturer's instructions (Sigma-Aldrich). The
concentrations selected for experimental testing--4 .mu.M for NSC 1758,
and 5 .mu.M for NSC 13987 and NSC 92938--reduced MTT metabolism by less
than 10% relative to untreated cultures.
[0131] Immunoprecipitation--
[0132] For calnexin mutant/Nef interaction analysis, HEK293T cells were
transfected with HA-tagged calnexin mutants and Nef.sub.BRU expression
plasmid. Cells were lysed 48 h post-transfection with 1% IGEPAL and 0.1%
SDS lysis buffer on ice for 30 min. Lysates were incubated with anti-HA
agarose beads for 2 h at 4.degree. C. with rotation. Respective
immunoprecipitates were washed three times with TBS (150 mM NaCl, 30 mM
Tris-HCl, 5 mM EDTA, pH 7.5). Bound complexes were eluted by boiling in
sample buffer for 5 min. Supernatants were separated by SDS-PAGE for
immunoblotting. Immunoprecipitation of calnexin from cells transfected
with pCG-NL4-3-IRES-GFP or mutant variant was performed similarly with
the following modifications. Cell lysates were incubated with monoclonal
anti-calnexin antibody for 2 h with rotation at 4.degree. C. EZView
protein A agarose beads were then added and the mix was further incubated
for 1 h at 4.degree. C. with rotation. Bound complexes were recovered as
described above. For studies of Nef/CNX interactions in the presence of
compounds, HEK293T cells were first transfected with HA-tagged Nef and
compounds were added after 6 h. Cells were lysed 48 h post-transfection
and immunoprecipitation was carried out using anti-HA agarose beads as
described above.
[0133] Molecular Modeling and Docking--
[0134] Structure modeling of the calnexin cytoplasmic domain was performed
using servers Hhpred (51), iTasser (52), ModWeb (53), Phyre2 (54), and
RaptorX (55), with subsequent quality assessment of the obtained models
and building of the final model by the QA-Recombinelt server (56). The
Modbase (53) GI 66933005 model based on PDB 1JHN (96% sequence identity)
was used for the lumenal domain structure. Nef structure has been modeled
using as templates the crystallographic and solution NMR experimental
structures covering different parts of Nef sequence, available from the
PDB (57): 4EN2, 3TB8, 4EMZ, 3REB, 3RBB, 3REA, 1EFN. These structures are
based on the HIV-1 sequences P03404, P03406, P03407, Q90VU7 (Uniprot
(58)). Modeling was performed for the target sequence P03407 (HIV-1 group
M subtype B isolate ARV2/BRU) with servers Hhpred, iTasser, M4T (59),
ModWeb, Phyre2, Swiss-Model (60). The resulting models have been then
submitted to the QA-Recombinelt server, producing the final model used
for interactions prediction.
[0135] In order to obtain indications as to which regions of Nef can
represent interactions interfaces, location of possible interactions
sites has been estimated with a sequence-based method ConSurf (25).
Sequence conservation for Nef has been assessed by constructing multiple
alignments using T-Coffee (61). We have subsequently carried out docking
of the structure models of calnexin cytoplasmic domain and Nef to
identify the sites in Nef interacting with calnexin. Docking was
performed using servers Cluspro (62), HEX (63), SwarmDock (64), Zdock
(65), each run producing 10 best models. To obtain a representative array
of docking models, docking has been carried out for calnexin and Nef
submitted to docking runs alternatively as receptor and ligand. Since
both calnexin cytoplasmic domain and Nef bind to ER membrane, the
resulting docking models that were able to disrupt this binding have been
filtered out from the final data.
[0136] To assess average number of interactions for each residue position
in Nef and CNX sequences in the set of docking models of binding between
CNX cytoplasmic domain and Nef, the overall number of Nef-CNX
interactions for all models, for each residue in Nef and CNX involved in
intermolecular interaction has been calculated. Number of interactions
for each amino acid residue in Nef and CNX is the total number of
interactions for this residue in docking models where such interaction
was identified.
[0137] Virtual Screening--
[0138] structure-based virtual screening (docking-based) was carried out
on the NCI Plated 2007 dataset (http://zinc.docking.org/catalogs/ncip)
from Zinc database (http://zinc.docking.org/)(66). Locally installed
docking program AutoDock Vina (34) has been used for screening.
[0139] HIV Infection--
[0140] HIV particles pseudotyped with VSV-G were produced from HEK293T
cells by transfecting with pCG-NL4-3-IRES-GFP or Nef mutant derivative.
Monocyte-derived macrophages were infected with the respective wild-type
or mutant virus particles normalized by RT activity. Infection was
allowed to proceed for 10 days and the level of infection was monitored
by RT assay.
[0141] Cholesterol Efflux--
[0142] Infected cells were seeded in a 24-well plate and labeled with
[.sup.3H] cholesterol for 48 h. Following this step, cells were washed
with PBS to remove any free cholesterol and efflux was initiated by
adding apoA-I (20 .mu.g/mL) and incubating for 3 h in serum free medium.
The media from the wells was then carefully collected and any cell debris
was removed by centrifuging at 5,000 rpm for 5 min. Cell monolayers were
lysed with 1% Triton X-100. Level of radioactivity in the media as well
as in the cells was determined by scintillation counting. Cholesterol
efflux was calculated as the percentage of radioactivity in the media
divided by the total amount measured in the cells and media. Cholesterol
efflux in the presence of compounds was performed similarly with the
following modifications. THP-1 cells were first transfected with BRU Nef
using Lipofectamine.TM. LTX reagent (ThermoFisher Scientific). Compounds
were added to cells 6 h post transfection and incubated overnight. The
following day cells were washed with PBS and treatment with compounds was
continued for 48 h with the addition of [.sup.3H] cholesterol and Phorbol
12-myristate 13-acetate (PMA). Efflux measurements were then performed as
described above.
[0143] Nef Sequence(s)--
[0144] HIV-1 group M is the most is the most common type of HIV accounting
for more than 90% of the AIDS epidemic. Within this group are several
subtypes, the most common of which are Subtypes A-H. In the example
above, a consensus Nef sequence (Nef consB).
[0145] The nucleotide sequence of this consensus sequence is:
TABLE-US-00001
atgggtggcaagtggtcaaaacgtagtgtggttggatggcctgctgtaag
ggaaagaatgagacgagctgagccagcagcagatggggtgggagcagtat
ctcgagacctggaaaaacatggagcaatcacaagtagcaatacagcagct
aacaatgctgattgtgcctggctagaagcacaagaggaggaggaggtggg
ttttccagtcagacctcaggtacctttaagaccaatgacttacaaggcag
ctgtagatcttagccactttttaaaagaaaaggggggactggaagggcta
atttactcccaaaaaagacaagatatccttgatctgtgggtctaccacac
acaaggctacttccctgattggcagaactacacaccagggccagggatca
gatatccactgacctttggatggtgcttcaagctagtaccagttgagcca
gagaaggtagaagaggccaatgaaggagagaacaacagcttgttacaccc
tatgagcctgcatgggatggatgacccggagaaagaagtgttagtgtgga
agtttgacagccgcctagcatttcatcacatggcccgagagctgcatccg
gagtactacaaggactgctga
[0146] The amino acid sequence of the consensus sequence is:
TABLE-US-00002
MGGKWSKRSVVGWPAVRERMRRAEPAADGVGAVSRDLEKHGAITSSNTAA
NNADCAWLEAQEEEEVGFPVRPQVPLRPMTYKAAVDLSHFLKEKGGLEGL
IYSQKRQDILDLWVYHTQGYFPDWQNYTPGPGIRYPLTFGWCFKLVPVEP
EKVEEANEGENNSLLHPMSLHGMDDPEKEVLVWKFDSRLAFHHMARELHP
EYYKDC.
[0147] This consensus sequence was previously developed by comparing the
Nef sequences of the HIV Subtypes A-H (67). All Nef sequences of these
HIV Subtypes have a conserved lysine at the 4.sup.th and 7.sup.th
positions. The consensus sequence described in the example was
specifically derived from HIV subtype B.
[0148] Calnexin Sequence--
[0149] In the example above, the nucleotide sequence of Calnexin is:
TABLE-US-00003
ATGGAAGGGAAGTGGTTGCTGTGTATGTTACTGGTGCTTGGAACTGCTAT
TGTTGAGGCTCATGATGGACATGATGATGATGTGATTGATATTGAGGATG
ACCTTGACGATGTCATTGAAGAGGTAGAAGACTCAAAACCAGATACCACT
GCTCCTCCTTCATCTCCCAAGGTTACTTACAAAGCTCCAGTTCCAACAGG
GGAAGTATATTTTGCTGATTCTTTTGACAGAGGAACTCTGTCAGGGTGGA
TTTTATCCAAAGCCAAGAAAGACGATACCGATGATGAAATTGCCAAATAT
GATGGAAAGTGGGAGGTAGAGGAAATGAAGGAGTCAAAGCTTCCAGGTGA
TAAAGGACTTGTGTTGATGTCTCGGGCCAAGCATCATGCCATCTCTGCTA
AACTGAACAAGCCCTTCCTGTTTGACACCAAGCCTCTCATTGTTCAGTAT
GAGGTTAATTTCCAAAATGGAATAGAATGTGGTGGTGCCTATGTGAAACT
GCTTTCTAAAACACCAGAACTCAACCTGGATCAGTTCCATGACAAGACCC
CTTATACGATTATGTTTGGTCCAGATAAATGTGGAGAGGACTATAAACTG
CACTTCATCTTCCGACACAAAAACCCCAAAACGGGTATCTATGAAGAAAA
ACATGCTAAGAGGCCAGATGCAGATCTGAAGACCTATTTTACTGATAAGA
AAACACATCTTTACACACTAATCTTGAATCCAGATAATAGTTTTGAAATA
CTGGTTGACCAATCTGTGGTGAATAGTGGAAATCTGCTCAATGACATGAC
TCCTCCTGTAAATCCTTCACGTGAAATTGAGGACCCAGAAGACCGGAAGC
CCGAGGATTGGGATGAAAGACCAAAAATCCCAGATCCAGAAGCTGTCAAG
CCAGATGACTGGGATGAAGATGCCCCTGCTAAGATTCCAGATGAAGAGGC
CACAAAACCCGAAGGCTGGTTAGATGATGAGCCTGAGTACGTACCTGATC
CAGACGCAGAGAAACCTGAGGATTGGGATGAAGACATGGATGGAGAATGG
GAGGCTCCTCAGATTGCCAACCCTAGATGTGAGTCAGCTCCTGGATGTGG
TGTCTGGCAGCGACCTGTGATTGACAACCCCAATTATAAAGGCAAATGGA
AGCCTCCTATGATTGACAATCCCAGTTACCAGGGAATCTGGAAACCCAGG
AAAATACCAAATCCAGATTTCTTTGAAGATCTGGAACCTTTCAGAATGAC
TCCTTTTAGTGCTATTGGTTTGGAGCTGTGGTCCATGACCTCTGACATTT
TTTTTGACAACTTTATCATTTGTGCTGATCGAAGAATAGTTGATGATTGG
GCCAATGATGGATGGGGCCTGAAGAAAGCTGCTGATGGGGCTGCTGAGCC
AGGCGTTGTGGGGCAGATGATCGAGGCAGCTGAAGAGCGCCCGTGGCTGT
GGGTAGTCTATATTCTAACTGTAGCCCTTCCTGTGTTCCTGGTTATCCTC
TTCTGCTGTTCTGGAAAGAAACAGACCAGTGGTATGGAGTATAAGAAAAC
TGATGCACCTCAACCGGATGTGAAGGAAGAGGAAGAAGAGAAGGAAGAGG
AAAAGGACAAGGGAGATGAGGAGGAGGAAGGAGAAGAGAAACTTGAAGAG
AAACAGAAAAGTGATGCTGAAGAAGATGGTGGCACTGTCAGTCAAGAGGA
GGAAGACAGAAAACCTAAAGCAGAGGAGGATGAAATTTTGAACAGATCAC
CAAGAAACAGAAAGCCACGAAGAGAGTGA
[0150] The amino acid sequence is:
TABLE-US-00004
MEGKWLLCMLLVLGTAIVEAHDGHDDDVIDIEDDLDDVIEEVEDSKPDTT
APPSSPKVTYKAPVPTGEVYFADSFDRGTLSGWILSKAKKDDTDDEIAKY
DGKWEVEEMKESKLPGDKGLVLMSRAKHHAISAKLNKPFLFDTKPLIVQY
EVNFQNGIECGGAYVKLLSKTPELNLDQFHDKTPYTIMFGPDKCGEDYKL
HFIFRHKNPKTGIYEEKHAKRPDADLKTYFTDKKTHLYTLILNPDNSFEI
LVDQSVVNSGNLLNDMTPPVNPSREIEDPEDRKPEDWDERPKIPDPEAVK
PDDWDEDAPAKIPDEEATKPEGWLDDEPEYVPDPDAEKPEDWDEDMDGEW
EAPQIANPRCESAPGCGVWQRPVIDNPNYKGKWKPPMIDNPSYQGIWKPR
KIPNPDFFEDLEPFRMTPFSAIGLELWSMTSDIFFDNFIICADRRIVDDW
ANDGWGLKKAADGAAEPGVVGQMIEAAEERPWLWVVYILTVALPVFLVIL
FCCSGKKQTSGMEYKKTDAPQPDVKEEEEEKEEEKDKGDEEEEGEEKLEE
KQKSDAEEDGGTVSQEEEDRKPKAEEDEILNRSPRNRKPRRE.
[0151] It should be understood that various alternatives to the
embodiments of the invention described herein may be employed in
practicing the invention. It is intended that the scope of the invention,
methods and structures within the scope of the invention includes
equivalents.
[0152] The embodiments illustrated and discussed in this specification are
intended only to teach those skilled in the art how to make and use the
invention. In describing embodiments of the invention, specific
terminology is employed for the sake of clarity. However, the invention
is not intended to be limited to the specific terminology so selected.
The above-described embodiments of the invention may be modified or
varied, without departing from the invention, as appreciated by those
skilled in the art in light of the above teachings. It is therefore to be
understood that, within the scope of the claims and their equivalents,
the invention may be practiced otherwise than as specifically described.
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Sequence CWU
1
1
1216PRTHomo sapiens 1Arg Lys Pro Arg Arg Glu1
528PRTArtificial SequenceDescription of Artificial Sequence Synthetic
8xHis tag 2His His His His His His His His1
5342DNAArtificial SequenceDescription of Artificial Sequence Synthetic
primer 3tttgctataa gatgggtggc gcgtggtcaa aaagtagtgt gg
42442DNAArtificial SequenceDescription of Artificial Sequence
Synthetic primer 4ccacactact ttttgaccac gcgccaccca tcttatagca aa
42540DNAArtificial SequenceDescription of Artificial
Sequence Synthetic primer 5gatgggtggc aagtggtcag caagtagtgt
ggttggatgg 40640DNAArtificial
SequenceDescription of Artificial Sequence Synthetic primer
6ccatccaacc acactacttg ctgaccactt gccacccatc
40734DNAArtificial SequenceDescription of Artificial Sequence Synthetic
primer 7gggtggcgcg tggtcagcaa gtagtgtggt tgga
34834DNAArtificial SequenceDescription of Artificial Sequence
Synthetic primer 8tccaaccaca ctacttgctg accacgcgcc accc
349621DNAArtificial SequenceDescription of Artificial
Sequence Synthetic polynucleotide 9atgggtggca agtggtcaaa acgtagtgtg
gttggatggc ctgctgtaag ggaaagaatg 60agacgagctg agccagcagc agatggggtg
ggagcagtat ctcgagacct ggaaaaacat 120ggagcaatca caagtagcaa tacagcagct
aacaatgctg attgtgcctg gctagaagca 180caagaggagg aggaggtggg ttttccagtc
agacctcagg tacctttaag accaatgact 240tacaaggcag ctgtagatct tagccacttt
ttaaaagaaa aggggggact ggaagggcta 300atttactccc aaaaaagaca agatatcctt
gatctgtggg tctaccacac acaaggctac 360ttccctgatt ggcagaacta cacaccaggg
ccagggatca gatatccact gacctttgga 420tggtgcttca agctagtacc agttgagcca
gagaaggtag aagaggccaa tgaaggagag 480aacaacagct tgttacaccc tatgagcctg
catgggatgg atgacccgga gaaagaagtg 540ttagtgtgga agtttgacag ccgcctagca
tttcatcaca tggcccgaga gctgcatccg 600gagtactaca aggactgctg a
62110206PRTArtificial
SequenceDescription of Artificial Sequence Synthetic polypeptide
10Met Gly Gly Lys Trp Ser Lys Arg Ser Val Val Gly Trp Pro Ala Val1
5 10 15Arg Glu Arg Met Arg Arg
Ala Glu Pro Ala Ala Asp Gly Val Gly Ala 20 25
30Val Ser Arg Asp Leu Glu Lys His Gly Ala Ile Thr Ser
Ser Asn Thr 35 40 45Ala Ala Asn
Asn Ala Asp Cys Ala Trp Leu Glu Ala Gln Glu Glu Glu 50
55 60Glu Val Gly Phe Pro Val Arg Pro Gln Val Pro Leu
Arg Pro Met Thr65 70 75
80Tyr Lys Ala Ala Val Asp Leu Ser His Phe Leu Lys Glu Lys Gly Gly
85 90 95Leu Glu Gly Leu Ile Tyr
Ser Gln Lys Arg Gln Asp Ile Leu Asp Leu 100
105 110Trp Val Tyr His Thr Gln Gly Tyr Phe Pro Asp Trp
Gln Asn Tyr Thr 115 120 125Pro Gly
Pro Gly Ile Arg Tyr Pro Leu Thr Phe Gly Trp Cys Phe Lys 130
135 140Leu Val Pro Val Glu Pro Glu Lys Val Glu Glu
Ala Asn Glu Gly Glu145 150 155
160Asn Asn Ser Leu Leu His Pro Met Ser Leu His Gly Met Asp Asp Pro
165 170 175Glu Lys Glu Val
Leu Val Trp Lys Phe Asp Ser Arg Leu Ala Phe His 180
185 190His Met Ala Arg Glu Leu His Pro Glu Tyr Tyr
Lys Asp Cys 195 200
205111779DNAHomo sapiens 11atggaaggga agtggttgct gtgtatgtta ctggtgcttg
gaactgctat tgttgaggct 60catgatggac atgatgatga tgtgattgat attgaggatg
accttgacga tgtcattgaa 120gaggtagaag actcaaaacc agataccact gctcctcctt
catctcccaa ggttacttac 180aaagctccag ttccaacagg ggaagtatat tttgctgatt
cttttgacag aggaactctg 240tcagggtgga ttttatccaa agccaagaaa gacgataccg
atgatgaaat tgccaaatat 300gatggaaagt gggaggtaga ggaaatgaag gagtcaaagc
ttccaggtga taaaggactt 360gtgttgatgt ctcgggccaa gcatcatgcc atctctgcta
aactgaacaa gcccttcctg 420tttgacacca agcctctcat tgttcagtat gaggttaatt
tccaaaatgg aatagaatgt 480ggtggtgcct atgtgaaact gctttctaaa acaccagaac
tcaacctgga tcagttccat 540gacaagaccc cttatacgat tatgtttggt ccagataaat
gtggagagga ctataaactg 600cacttcatct tccgacacaa aaaccccaaa acgggtatct
atgaagaaaa acatgctaag 660aggccagatg cagatctgaa gacctatttt actgataaga
aaacacatct ttacacacta 720atcttgaatc cagataatag ttttgaaata ctggttgacc
aatctgtggt gaatagtgga 780aatctgctca atgacatgac tcctcctgta aatccttcac
gtgaaattga ggacccagaa 840gaccggaagc ccgaggattg ggatgaaaga ccaaaaatcc
cagatccaga agctgtcaag 900ccagatgact gggatgaaga tgcccctgct aagattccag
atgaagaggc cacaaaaccc 960gaaggctggt tagatgatga gcctgagtac gtacctgatc
cagacgcaga gaaacctgag 1020gattgggatg aagacatgga tggagaatgg gaggctcctc
agattgccaa ccctagatgt 1080gagtcagctc ctggatgtgg tgtctggcag cgacctgtga
ttgacaaccc caattataaa 1140ggcaaatgga agcctcctat gattgacaat cccagttacc
agggaatctg gaaacccagg 1200aaaataccaa atccagattt ctttgaagat ctggaacctt
tcagaatgac tccttttagt 1260gctattggtt tggagctgtg gtccatgacc tctgacattt
tttttgacaa ctttatcatt 1320tgtgctgatc gaagaatagt tgatgattgg gccaatgatg
gatggggcct gaagaaagct 1380gctgatgggg ctgctgagcc aggcgttgtg gggcagatga
tcgaggcagc tgaagagcgc 1440ccgtggctgt gggtagtcta tattctaact gtagcccttc
ctgtgttcct ggttatcctc 1500ttctgctgtt ctggaaagaa acagaccagt ggtatggagt
ataagaaaac tgatgcacct 1560caaccggatg tgaaggaaga ggaagaagag aaggaagagg
aaaaggacaa gggagatgag 1620gaggaggaag gagaagagaa acttgaagag aaacagaaaa
gtgatgctga agaagatggt 1680ggcactgtca gtcaagagga ggaagacaga aaacctaaag
cagaggagga tgaaattttg 1740aacagatcac caagaaacag aaagccacga agagagtga
177912592PRTHomo sapiens 12Met Glu Gly Lys Trp Leu
Leu Cys Met Leu Leu Val Leu Gly Thr Ala1 5
10 15Ile Val Glu Ala His Asp Gly His Asp Asp Asp Val
Ile Asp Ile Glu 20 25 30Asp
Asp Leu Asp Asp Val Ile Glu Glu Val Glu Asp Ser Lys Pro Asp 35
40 45Thr Thr Ala Pro Pro Ser Ser Pro Lys
Val Thr Tyr Lys Ala Pro Val 50 55
60Pro Thr Gly Glu Val Tyr Phe Ala Asp Ser Phe Asp Arg Gly Thr Leu65
70 75 80Ser Gly Trp Ile Leu
Ser Lys Ala Lys Lys Asp Asp Thr Asp Asp Glu 85
90 95Ile Ala Lys Tyr Asp Gly Lys Trp Glu Val Glu
Glu Met Lys Glu Ser 100 105
110Lys Leu Pro Gly Asp Lys Gly Leu Val Leu Met Ser Arg Ala Lys His
115 120 125His Ala Ile Ser Ala Lys Leu
Asn Lys Pro Phe Leu Phe Asp Thr Lys 130 135
140Pro Leu Ile Val Gln Tyr Glu Val Asn Phe Gln Asn Gly Ile Glu
Cys145 150 155 160Gly Gly
Ala Tyr Val Lys Leu Leu Ser Lys Thr Pro Glu Leu Asn Leu
165 170 175Asp Gln Phe His Asp Lys Thr
Pro Tyr Thr Ile Met Phe Gly Pro Asp 180 185
190Lys Cys Gly Glu Asp Tyr Lys Leu His Phe Ile Phe Arg His
Lys Asn 195 200 205Pro Lys Thr Gly
Ile Tyr Glu Glu Lys His Ala Lys Arg Pro Asp Ala 210
215 220Asp Leu Lys Thr Tyr Phe Thr Asp Lys Lys Thr His
Leu Tyr Thr Leu225 230 235
240Ile Leu Asn Pro Asp Asn Ser Phe Glu Ile Leu Val Asp Gln Ser Val
245 250 255Val Asn Ser Gly Asn
Leu Leu Asn Asp Met Thr Pro Pro Val Asn Pro 260
265 270Ser Arg Glu Ile Glu Asp Pro Glu Asp Arg Lys Pro
Glu Asp Trp Asp 275 280 285Glu Arg
Pro Lys Ile Pro Asp Pro Glu Ala Val Lys Pro Asp Asp Trp 290
295 300Asp Glu Asp Ala Pro Ala Lys Ile Pro Asp Glu
Glu Ala Thr Lys Pro305 310 315
320Glu Gly Trp Leu Asp Asp Glu Pro Glu Tyr Val Pro Asp Pro Asp Ala
325 330 335Glu Lys Pro Glu
Asp Trp Asp Glu Asp Met Asp Gly Glu Trp Glu Ala 340
345 350Pro Gln Ile Ala Asn Pro Arg Cys Glu Ser Ala
Pro Gly Cys Gly Val 355 360 365Trp
Gln Arg Pro Val Ile Asp Asn Pro Asn Tyr Lys Gly Lys Trp Lys 370
375 380Pro Pro Met Ile Asp Asn Pro Ser Tyr Gln
Gly Ile Trp Lys Pro Arg385 390 395
400Lys Ile Pro Asn Pro Asp Phe Phe Glu Asp Leu Glu Pro Phe Arg
Met 405 410 415Thr Pro Phe
Ser Ala Ile Gly Leu Glu Leu Trp Ser Met Thr Ser Asp 420
425 430Ile Phe Phe Asp Asn Phe Ile Ile Cys Ala
Asp Arg Arg Ile Val Asp 435 440
445Asp Trp Ala Asn Asp Gly Trp Gly Leu Lys Lys Ala Ala Asp Gly Ala 450
455 460Ala Glu Pro Gly Val Val Gly Gln
Met Ile Glu Ala Ala Glu Glu Arg465 470
475 480Pro Trp Leu Trp Val Val Tyr Ile Leu Thr Val Ala
Leu Pro Val Phe 485 490
495Leu Val Ile Leu Phe Cys Cys Ser Gly Lys Lys Gln Thr Ser Gly Met
500 505 510Glu Tyr Lys Lys Thr Asp
Ala Pro Gln Pro Asp Val Lys Glu Glu Glu 515 520
525Glu Glu Lys Glu Glu Glu Lys Asp Lys Gly Asp Glu Glu Glu
Glu Gly 530 535 540Glu Glu Lys Leu Glu
Glu Lys Gln Lys Ser Asp Ala Glu Glu Asp Gly545 550
555 560Gly Thr Val Ser Gln Glu Glu Glu Asp Arg
Lys Pro Lys Ala Glu Glu 565 570
575Asp Glu Ile Leu Asn Arg Ser Pro Arg Asn Arg Lys Pro Arg Arg Glu
580 585 590
* * * * *