Fig. 3
From: Epigenetic regulation of HIV-1 latency: focus on polycomb group (PcG) proteins
A simplified overview of epigenetic modifications in HIV-1 latency. Several factors regulate HIV-1 latency. HMTs (Suv39h1, G9a, and EZH2) methylate histones at nuc-1. Cellular transcription factors (p50/p50 homodimers, CTIP-2, and YY1 etc) recruit HDACs to 5′ of viral LTR and maintain epigenetically silenced chromatin structure. Sp1 interacts with CTIP-2 and recruits Suv39h1 and HDACs at HIV-1 5′ LTR. Ras-responsive binding factor 2 (RBF 2) is a multicomponent complex that consists of upstream stimulatory factor 1-2 (USF1/2). RBF 2 also contains a multifunctional factor TFII-I. RBF 2 complex recruits HDACs at ras-responsive binding elements (RBEs) and regulates HIV-1 transcription. Two CpG islands flank the HIV-1 transcription start site (TSS) and are methylated by DNMTs in latently infected viral reservoirs