Project description:Although HIV-1 integration sites are considered to favor active transcription units in the human genome, high-resolution analysis of individual HIV-1 integration sites have shown that the virus can integrate in a variety of host genomic locations, including non-genic regions, challenging the traditional understanding of HIV-1 integration site selection. Here, we showed that HIV-1 targets R-loops, a genomic structure made up of DNA–RNA hybrids, for integration. HIV-1 initiates the formation of R-loops in both genic and non-genic regions of the host genome and preferentially integrates into regions of HIV-1-induced R-loops. Using a cell model that can independently control transcriptional activity and R-loop formation, we demonstrated that the presence of R-loops, regardless of transcriptional activity, directs HIV-1 integration targeting sites. We also found that HIV-1 integrase proteins bind to the host genomic R-loops. These findings provide fundamental insights into the mechanisms of retroviral integration and the new strategies of antiretroviral therapy against HIV-1 latent infection.
Project description:Although HIV-1 integration sites are considered to favor active transcription units in the human genome, high-resolution analysis of individual HIV-1 integration sites have shown that the virus can integrate in a variety of host genomic locations, including non-genic regions, challenging the traditional understanding of HIV-1 integration site selection. Here, we showed that HIV-1 targets R-loops, a genomic structure made up of DNA–RNA hybrids, for integration. HIV-1 initiates the formation of R-loops in both genic and non-genic regions of the host genome and preferentially integrates into regions of HIV-1-induced R-loops. Using a cell model that can independently control transcriptional activity and R-loop formation, we demonstrated that the presence of R-loops, regardless of transcriptional activity, directs HIV-1 integration targeting sites. We also found that HIV-1 integrase proteins bind to the host genomic R-loops. These findings provide fundamental insights into the mechanisms of retroviral integration and the new strategies of antiretroviral therapy against HIV-1 latent infection.
Project description:Although HIV-1 integration sites are considered to favor active transcription units in the human genome, high-resolution analysis of individual HIV-1 integration sites have shown that the virus can integrate in a variety of host genomic locations, including non-genic regions, challenging the traditional understanding of HIV-1 integration site selection. Here, we showed that HIV-1 targets R-loops, a genomic structure made up of DNA–RNA hybrids, for integration. HIV-1 initiates the formation of R-loops in both genic and non-genic regions of the host genome and preferentially integrates into regions of HIV-1-induced R-loops. Using a cell model that can independently control transcriptional activity and R-loop formation, we demonstrated that the presence of R-loops, regardless of transcriptional activity, directs HIV-1 integration targeting sites. We also found that HIV-1 integrase proteins bind to the host genomic R-loops. These findings provide fundamental insights into the mechanisms of retroviral integration and the new strategies of antiretroviral therapy against HIV-1 latent infection.
Project description:We investigated the link between HIV-1 integration by using B-HIVE and LEDGINs. B-HIVE tracks insert-specific HIV expression by tagging a unique barcode in the HIV genome. LEDGINs are antivirals that inhibit the interaction between HIV-IN and its chromatin tethering cofactor LEDGF/p75. They are known to retarget HIV-1 integration sites. Here, we confirmed that LEDGIN treatment retargets integration out of transcriptionally active regions and reduce HIV expression. Silent provirus was located at increased distance to H3K36me3, the recognition marker of LEDGF/p75, after treatment with LEDGINs. Viral RNA expression was also influenced by the proximity of enhancers, regardless of the presence of LEDGINs.
Project description:Detection of viruses by innate immune sensors induces protective antiviral immunity. The viral DNA sensor cGAS is necessary for detection of HIV by human dendritic cells and macrophages. However, synthesis of HIV DNA during infection is not sufficient for immune activation. The capsid protein, which associates with viral DNA, has a pivotal role in enabling cGAS-mediated immune activation. We now find that NONO is an essential sensor of the HIV capsid in the nucleus. NONO protein directly binds capsid with higher affinity for weakly pathogenic HIV-2 than highly pathogenic HIV-1. Upon infection, NONO is essential for cGAS activation by HIV and cGAS association with HIV DNA in the nucleus. NONO recognizes a conserved region in HIV capsid with limited tolerance for escape mutations. Detection of nuclear viral capsid by NONO to promote DNA sensing by cGAS reveals an innate strategy to achieve distinction of viruses from self in the nucleus.
Project description:Retroviral integration is mediated by a unique enzymatic process shared by all retroviruses and retrotransposons. During integration, double-stranded linear viral DNA is inserted into the host genome in a process catalyzed by viral-encoded integrase. However, host cell defenses against HIV-1 integration are not clear. This study identifies -catenin-like protein 1 (CTNNBL1) as a potent inhibitor of HIV-1 integration via association with viral IN and its cofactor, lens epithelium-derived growth factor/p75. CTNNBL1 overexpression blocks HIV-1 integration and inhibits viral replication, whereas CTNNBL1 depletion significantly upregulates HIV-1 integration into the genome of various target cells. Further, CTNNBL1 expression is downregulated in CD4+ T cells by activation, and CTNNBL1 depletion also facilitates HIV-1 integration in resting CD4+ T cells. Thus, host cells may employ CTNNBL1 to inhibit HIV-1 integration into the genome. This finding suggests a strategy for the treatment of HIV infections.