GSE183275
T cell stimulation alters the HIV-1 reservoir by differential activation of proviral chromatin
The reservoir of latently HIV-1 infected cells is heterogeneous. To achieve an HIV-1 cure the reservoir of activatable proviruses should be removed, whereas permanently silenced proviruses may be tolerated.   We have developed a method to assess the proviral nuclear microenvironment in single cells. Latently HIV-1 infected cells were transduced with a zinc finger protein specifically binding to the HIV-1 promoter, producing a fluorescent signal as the viral transactivator Tat is recruited to the HIV-1 promoter. In these cells we assessed the proviral chromatin composition simultaneously with the proviral activation.   By linking the Tat promoter recruitment to viral activation, we dissected the mechanisms of HIV-1 reactivation and the consequences of HIV-1 production. A pulse of promoter-associated Tat was identified that contrasts to the continuous production of viral proteins. As expected, promoter H3K4me3 led to massive expression of the provirus following T cell stimulation. However, the activation induced cell cycle arrest and death resulted in an expanded surviving cell fraction with proviruses encapsulated in repressive chromatin. Further, this model can be used to reveal mechanisms of action of small molecules. In a proof-of-concept study we determine the effect of CBP/P300-inhibitor GNE049. We found that only active enhancers, associated with H3K4me1 and H3K27ac, efficiently recruit Tat, as GNE049 that specifically inhibits enhancer H3K27ac also depletes promoter Tat. Despite the absence of Tat, HIV-1 latency reversal still occurred.   Single cell assessment of the chromatin composition of the latent HIV-1 proviruses revealed how T cell stimulation modulates the proviral activity and the subsequent fate of the infected cell. Overall design: Localization of Tat and ZFP3-FLAG proteins in the chromatin of HIV-1 infected cells..