Tat inhibition by didehydro-Cortistatin A promotes heterochromatin formation at the HIV-1 long terminal repeat
Tat inhibition by didehydro-Cortistatin A promotes heterochromatin formation at the HIV-1 long terminal repeat
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DOI：
10.1186/s13072-019-0267-8
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发表时间：
2019-04-16
影响因子：
3.9
通讯作者：
Valente, Susana T.
中科院分区：
文献类型：
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作者：
Li, Chuan;Mousseau, Guillaume;Valente, Susana T.
背景：整合的HIV-1启动子的转录直接受其染色质环境的控制，转录起始位点下游的核小体-1直接阻碍HIV-1启动子的转录。HIV-1 Tat蛋白通过结合病毒mRNA发夹（TAR）和招募转录因子来促进转录伸长，从而调节病毒潜伏期向主动转录的过渡。Tat抑制剂双脱氢皮质抑素A （dCA）抑制转录，随着时间的推移，缺乏低级别转录事件，触发潜伏位点的表观遗传变化，将HIV转录锁定在潜伏状态。结果：我们利用HIV-1潜伏期和活性转录的多细胞系模型研究了这些表观遗传变化。我们证明，dCA处理不会改变HIV-1启动子上的经典核小体定位，但会促进核小体/DNA更紧密的关联，这与核小体-1上去乙酰化的H3占用增加有关。SWI/SNF染色质重塑复合体PBAF的募集也受到抑制，而抑制性BAF复合体的募集则得到增强，而PBAF复合体是tat介导的转激活所必需的。这些结果得到了HIV基因组上RNA聚合酶II招募缺失的支持，即使在潜伏期逆转药物的强烈刺激下也是如此。在Tat- tar不合格前病毒的潜伏期细胞系模型中未检测到表观遗传变化，证实了dCA对Tat的特异性。结论：我们在HIV基因组上表征了dca介导的表观遗传特征，这转化为对HIV表达的有效阻断作用，进一步增强了Tat抑制剂在阻断和锁定功能治疗方法中的潜力。
Background: Transcription from the integrated HIV-1 promoter is directly governed by its chromatin environment, and the nucleosome-1 downstream from the transcription start site directly impedes transcription from the HIV-1 promoter. The HIV-1 Tat protein regulates the passage from viral latency to active transcription by binding to the viral mRNA hairpin (TAR) and recruiting transcriptional factors to promote transcriptional elongation. The Tat inhibitor didehydro-Cortistatin A (dCA) inhibits transcription and overtime, the lack of low-grade transcriptional events, triggers epigenetic changes at the latent loci that lock HIV transcription in a latent state.Results: Here we investigated those epigenetic changes using multiple cell line models of HIV-1 latency and active transcription. We demonstrated that dCA treatment does not alter the classic nucleosome positioning at the HIV-1 promoter, but promotes tighter nucleosome/DNA association correlating with increased deacetylated H3 occupancy at nucleosome-1. Recruitment of the SWI/SNF chromatin remodeling complex PBAF, necessary for Tat-mediated transactivation, is also inhibited, while recruitment of the repressive BAF complex is enhanced. These results were supported by loss of RNA polymerase II recruitment on the HIV genome, even during strong stimulation with latency-reversing agents. No epigenetic changes were detected in cell line models of latency with Tat-TAR incompetent proviruses confirming the specificity of dCA for Tat.Conclusions: We characterized the dCA-mediated epigenetic signature on the HIV genome, which translates into potent blocking effects on HIV expression, further strengthening the potential of Tat inhibitors in block-and-lock functional cure approaches.