Transcript P-TEFb equilibrium in cells modulates HIV latency

Lost in transcription – mechanisms that
drive HIV latency
Ongoing Projects
i.
ii.
iii.
Regulation of HIV transcription and mechanisims of
latency.
viral – host interactions.
Use of lentiviruses for targeting specific cells for gene
therpy application.
Ongoing Collaborations
•
•
Dan Levy - Role of SETD6 in modulating HIV
latency.
Alon Freidman – Targeting of lentiviruses to specific
cells.
People
The Problem - latency is a block for HIV eradication
HAART
New HIV infections
Latent HIV
reservoirs that
are refractory
to therapy
AIDS- related deaths
People
Total: 34.2 million
HIV infected
Latency - a reversibly low-productive state of infection,
where infected cells retain the capacity to fully reemerge and produce de-novo viral particles
What are the molecular mechanisms
that regulate HIV latency ?
Regulation of HIV
transcriptional activation
HYPOTHESIS
Role of Positive transcription
elongation b -PTEFb
Ways to reactivate latent HIV and
eliminate viral reservoirs with
HAART ?
Latency corresponds with transcription activation
and chromatin state
A
P-TEFb
HATs
Active State
Open chromatin
NF-kB
TAFs…
NF-AT
SWI/SNF
remodeling
HIV Provirus
5’LTR
gag
rev
tat
env
vif
pol
3’LTR
Ac
Ac
met
met
nef
vpr vpu
Ac
B
Latent State
Condensed chromatin
HDACs
NF-AT
CCR5/CXCR4 CD4
HIV provirus
NF-kB
TAFs…
Ac
YY1/LSF
CBF-1
AP4
PRC1/2
Remodeling
EZH2
HKMT/
met
H3K9
me2
nuc1
H3K27
me3
met
SUV39H1
G9a
CpG islands
HIV Tat - a master switch of viral transcription
Cyclin T1
P-TEFb
HIV Tat
CDK9
TAR
P P
PP
LTR
RNA Polymerase II
Recruitment modes of P-TEFb to the viral promoter
Tat independent (basal)
I
II
SEC
SEC
AFF4
Cdk9
CycT
P
1A
ELL
2
ENL/
AF9
ENL/
AF9
ELL
2
YEATS
PAFc motif
Brd4
PID
Ac
A
P
TAR
AFF4
CycT P
1
Tat
Cdk9
P
Ac
P
NF-kB
CycT1
Ac
A
Cdk9
NEL P
F E
A-D
RelA/
p50
RNAPII
Tat dependent
III
SEC
TAT
A
TAR
LTR
NFk Sp1
B
Cdk9
P
P
P
CycT
1
HIV LTR
P
RNAPII
TAR
P
P
CT
D
DSIF
/ P
spt5
P-TEFb equilibrium in cells modulates HIV latency
P13K/
Akt
Brd4
P P
Cdk9
HEXIM1
Ub
HEXIM1
MePCE
CycT1
LARP7
3’
Tat
PKC activators (Bryostatin, •
Prostratin)
HDAC inhibitors ( SAHA) •
Bromodomain and extra-terminal •
(BET) bromodomain inhibitors (JQ1, IBET)
Hypertrophic or stress signals (UV), •
TCR ligation (IL-2/CD3 Ab)
HIV infection •
T186
P
5’
Cdk9
7SK
snRNA
CycT1
P
P
Cdk9
CycT1
Ac
K380;386;390;404
Resting stat - inactive P-TEFb
Active state - free active PTEFb
What are the molecular mechanisms that
regulate HIV latency ?
Regulation of Transcriptional
activation
1
Role of P-TEFb in
establishment of HIV latency
2
Mechanisms that promote viral
gene activation
3
Modes of recruitment of PTEFb to the viral promoter.
4
identification of host factors
that modulate HIV latency
Ways to reactivate latent
HIV and eliminate viral
reservoirs ?
Role of chromatin
modulation (collaboration of
D.Levy)
Screen for small molecules
that can reactivate latent
HIV