HIV latency is reversed by ACSS2-driven histone crotonylation

Abstract

Eradication of HIV-1 (HIV) is hindered by stable viral reservoirs. Viral latency is epigenetically regulated. While the effects of histone acetylation and methylation at the HIV long-terminal repeat (LTR) have been described, our knowledge of the proviral epigenetic landscape is incomplete. We report that a previously unrecognized epigenetic modification of the HIV LTR, histone crotonylation, is a regulator of HIV latency. Reactivation of latent HIV was achieved following the induction of histone crotonylation through increased expression of the crotonyl-CoA-producing enzyme acyl-CoA synthetase short-chain family member 2 (ACSS2). This reprogrammed the local chromatin at the HIV LTR through increased histone acetylation and reduced histone methylation. Pharmacologic inhibition or siRNA knockdown of ACSS2 diminished histone crotonylation-induced HIV replication and reactivation. ACSS2 induction was highly synergistic in combination with either a protein kinase C agonist (PEP005) or a histone deacetylase inhibitor (vorinostat) in reactivating latent HIV. In the SIV-infected nonhuman primate model of AIDS, the expression of ACSS2 was significantly induced in intestinal mucosa in vivo, which correlated with altered fatty acid metabolism. Our study links the HIV/SIV infection-induced fatty acid enzyme ACSS2 to HIV latency and identifies histone lysine crotonylation as a novel epigenetic regulator for HIV transcription that can be targeted for HIV eradication.

Functions and mechanisms of lysine crotonylation

“…In vivo Interventional study Mice model 2018 42 Regulation of telomere maintenance Cell culture Interventional study MEF cells 2018 44 Regulation of HIV latency Cell culture Interventional study J-Lat A1 and CD4 + T cells 2018 47 Regulation of cancer In vivo and cell culture Interventional study HCC tissues and human hepatoma-derived cell 2019 51 In general, one protein may occur simultaneously multiple PTMs. 53 Indeed, recent years gradually intensifying research on crotonylation and many publications were dedicated to only one of the many possible lysine crotonylations.…”

Disruption of latent HIV in vivo during the clearance of actinic keratosis by ingenol mebutate

“…Similarly, HIV DNA levels were also much higher in CD4 + T cells in the peripheral blood than in the skin biopsies among untreated samples from these patients (1814.96 ± 1126.38 HIV DNA copies/million cells in CD4 + T cells compared with 39.97 ± 33.44 HIV DNA copies/million cells in skin biopsies) (Supplemental Table 3.). Previously we have shown that there may be a block at the level of the full-length HIV transcription during ART (15,16). Following the topical application of ingenol mebutate, there was no apparent change in the levels of the full-length HIV RNA [poly(A) + ] or in the initiation and elongation of the HIV transcripts in the CD4 + T cells from peripheral blood samples.…”

“…Total RNA was extracted from PBMC and from skin biopsies by acid guanidinium thiocyanate-phenol-chloroform extraction (Trireagent, Molecular Research Center) using Dounce tissue grinder protocol as previously described (15,16,25), subsequent isopropanol precipitation, and RNA quantification using a NanoDrop 1000 spectrophotometer. The HIV transcriptional profile was determined to infer the levels of initiation (TAR, short abortive transcripts), elongation (Kumar or Long LTR transcripts), or full transcription/completion of transcripts [poly(A) + transcripts] as previously published (15,16). The PCR primers/probes for this assay were previously reported to quantify initiation, elongation, or full transcription of HIV (7,8,26,27).…”

“…In this study, we sought to determine the effects of ingenol mebutate on HIV-infected cells in an accessible skin tissue compartment harboring multiple cell types. We have previously observed reversal of the different blocks to HIV transcription corresponding to different degrees of reactivated latent HIV infection of CD4 + T cells during LRA treatment in vitro and ex vivo (15,16).…”

Clinical pharmacology in HIV cure research – what impact have we seen?

“…It has been well recognized that epigenetic regulation of histone tails at the HIV LTR is critical for the establishment of latent reservoirs. Recent studies showed that HDACi or histone methyltransferase can reactivate HIV and some of these inhibitors have been investigated as LRAs in human clinical trials ( Table 2) [33]. First of all, it is worth mentioning the valproic acid, a well-known drug used commonly against seizures or migraine, which emerged as a potential LRA thank to a study supervised by Margolis and published on Lancet in 2005.…”