HIV persists in the face of highly active antiretroviral therapy (HAART) due to constitutive low-level replication in sites that are poorly accessible to drugs and the development of latent infections in a variety of types including the long-lived memory CD4+ T cell population, macrophages, and microglial cells in the brain - cells that play a critical role in neurologic dysfunction and neurotoxicity. The persistence of HIV mandates that patients be maintained on life-long therapy with its attendant costs and side effects. Furthermore, although HAART has greatly extended survival to patients infected with HIV-1, current therapy has failed to decrease the prevalence of HIV- neurological diseases especially in individuals who abuse drugs. This proposal focuses on defining the molecular basis for HIV silencing, the impact of drugs of abuse on the creation and reactivation of the latent viral reservoir in microglial cells, and the development of novel therapeutic approaches to attacking HIV latency. Key questions about HIV silencing that remain to be answered include: What are the primary sequence triggers and mechanisms that induce silencing (i.e. protein repressors and/or viral- derived RNA)? What conditions lead to proviral DNA methylation? Do similar silencing mechanisms operate in each of the cell types infected by HIV? How do drugs of abuse reactivate HIV? In partial answer to these questions we have demonstrated that distinct epigenetic silencing mechanisms lead to viral persistence in different cell types. Using novel unbiased shRNA screens we have shown that in T-cells, the polycomb repressive complex 2 (PCR2) plays a central role in maintaining proviral latency, whereas in microglial cells, PCR2 is absent and silencing is mediated by the SMRT and CoREST silencing machinery. Because of these differences in the silencing machinery we have been able to identify selective activators of HIV transcription in the two different cell types. Similarly, methamphetamine is able to reverse proviral latency in microglial cells through a novel activation pathway leading to NF-kB mobilization. This mechanism may outline the initial biochemical events leading to the observed increased neurodegeneration in HIV-positive individuals who use METH. Extending this work we plan to develop novel technologies allowing exploitation a natural epigenetic silencing mechanisms involving both histone and DNA methylation, to block HIV transcription.

National Institute of Health (NIH)
National Institute on Drug Abuse (NIDA)
NIH Director’s Pioneer Award (NDPA) (DP1)
Project #
Application #
Study Section
Special Emphasis Panel (ZDA1-NXR-B (12))
Program Officer
Satterlee, John S
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Case Western Reserve University
Schools of Medicine
United States
Zip Code
Chen, Yupeng; Zhang, Lirong; EstarĂ¡s, Conchi et al. (2014) A gene-specific role for the Ssu72 RNAPII CTD phosphatase in HIV-1 Tat transactivation. Genes Dev 28:2261-75
Tilton, Carisa A; Tabler, Caroline O; Lucera, Mark B et al. (2014) A combination HIV reporter virus system for measuring post-entry event efficiency and viral outcome in primary CD4+ T cell subsets. J Virol Methods 195:164-9
Jadlowsky, Julie K; Wong, Julian Y; Graham, Amy C et al. (2014) Negative elongation factor is required for the maintenance of proviral latency but does not induce promoter-proximal pausing of RNA polymerase II on the HIV long terminal repeat. Mol Cell Biol 34:1911-28
Mbonye, Uri; Karn, Jonathan (2014) Transcriptional control of HIV latency: cellular signaling pathways, epigenetics, happenstance and the hope for a cure. Virology 454-455:328-39
Karn, Jonathan (2013) A new BET on the control of HIV latency. Cell Cycle 12:545-6
Mbonye, Uri R; Gokulrangan, Giridharan; Datt, Manish et al. (2013) Phosphorylation of CDK9 at Ser175 enhances HIV transcription and is a marker of activated P-TEFb in CD4(+) T lymphocytes. PLoS Pathog 9:e1003338
Kim, Young Kyeung; Mbonye, Uri; Hokello, Joseph et al. (2011) T-cell receptor signaling enhances transcriptional elongation from latent HIV proviruses by activating P-TEFb through an ERK-dependent pathway. J Mol Biol 410:896-916
Friedman, Julia; Cho, Won-Kyung; Chu, Chung K et al. (2011) Epigenetic silencing of HIV-1 by the histone H3 lysine 27 methyltransferase enhancer of Zeste 2. J Virol 85:9078-89
Karn, Jonathan (2011) The molecular biology of HIV latency: breaking and restoring the Tat-dependent transcriptional circuit. Curr Opin HIV AIDS 6:4-11
Tyagi, Mudit; Pearson, Richard John; Karn, Jonathan (2010) Establishment of HIV latency in primary CD4+ cells is due to epigenetic transcriptional silencing and P-TEFb restriction. J Virol 84:6425-37