Identification of unrecognized host factors promoting HIV-1 latency

• Published in: PLoS pathogens 2020-12, Vol.16 (12), p.e1009055-e1009055
• Main Authors: Li, Zichong, Hajian, Cyrus, Greene, Warner C
• Format: Article
• Language: English
• Subjects: Biology and Life Sciences; CD4-Positive T-Lymphocytes - virology; Gene Expression Regulation, Viral; HIV Infections - metabolism; HIV Infections - physiopathology; HIV Infections - virology; HIV Seropositivity - genetics; HIV Seropositivity - immunology; HIV-1 - metabolism; HIV-1 - pathogenicity; HIV-1 - physiology; Host Microbial Interactions - genetics; Host Microbial Interactions - physiology; Humans; Jurkat Cells; Medicine and Health Sciences; Proviruses - genetics; Virus Activation - genetics; Virus Latency - physiology
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1009055

To counter HIV latency, it is important to develop a better understanding of the full range of host factors promoting latency. Their identification could suggest new strategies to reactivate latent proviruses and subsequently kill the host cells ("shock and kill"), or to permanently silence these latent proviruses ("block and lock"). We recently developed a screening strategy termed "Reiterative Enrichment and Authentication of CRISPRi Targets" (REACT) that can unambiguously identify host genes promoting HIV latency, even in the presence of high background "noise" produced by the stochastic nature of HIV reactivation. After applying this strategy in four cell lines displaying different levels of HIV inducibility, we identified FTSJ3, TMEM178A, NICN1 and the Integrator Complex as host genes promoting HIV latency. shRNA knockdown of these four repressive factors significantly enhances HIV expression in primary CD4 T cells, and active HIV infection is preferentially found in cells expressing lower levels of these four factors. Mechanistically, we found that downregulation of these newly identified host inhibitors stimulates different stages of RNA Polymerase II-mediated transcription of HIV-1. The identification and validation of these new host inhibitors provide insight into the novel mechanisms that maintain HIV latency even when cells are activated and undergo cell division.