中科院上海巴斯德所等揭示長鏈非編碼RNA調控HIV複製新機制

長鏈非編碼RNA（LncRNA）在表觀遺傳調控、免疫調節和細胞分化調控等方面的重要作用引起廣泛關注。近日，中國科學院上海巴斯德研究所王建華課題組在國際學術期刊《核酸研究》（Nucleic Acids Research）在線發表了題為Long noncoding RNA MALAT1 releases epigenetic silencing of HIV-1 replication by displacing the polycomb repressive complex 2 from binding to the LTR promoter的研究論文。研究揭示了長鏈非編碼RNA（LncRNA）MALAT1誘使抑制性PRC2（polycomb repressive complex 2）複合物從HIV啟動子LTR（長末端重複）解離從而促進HIV轉錄和複製。研究揭示LncRNA MALAT1調控HIV複製的重要作用和分子機制，為抗病毒策略設計提供了宿主新靶點。

HIV高度依賴宿主因子完成複製周期，鑒定調節HIV複製的關鍵宿主因子可為抗病毒策略設計提供宿主新靶點。王建華研究組利用組學技術篩選了多種能夠調控HIV複製的宿主蛋白，如宿主蛋白SUN2通過維持HIV-LTR啟動子區域異染色質結構抑制HIV轉錄和複製（2018，mBio）；SAFB1通過抑制RNA聚合酶II的磷酸化並抑制其與HIV LTR的結合，抑制HIV的轉錄，維持HIV潛伏（2018，J.Bio.Chem）；而宿主蛋白Naf1則是通過抑制NF-kB 信號通路抑制HIV複製（2016，J Virol）。

近年來，長鏈非編碼RNA（LncRNA）在表觀遺傳調控、免疫調節和細胞分化調控等方面的重要作用引起廣泛關注。在調節HIV感染方面，通過靶向不同的細胞蛋白機器或信號通路，LncRNA可抑制或促進HIV複製。LncRNA MALAT1在腫瘤細胞中高表達，常被認為是腫瘤轉移的標記物。MALAT1主要定位於細胞核核斑區，可參與基因轉錄和pre-mRNAs的選擇性剪接等細胞生理過程。

王建華課題組聯合武漢大學教授侯煒利用RNA-seq技術篩選出MALAT1在HIV感染細胞中高表達；高表達的MALAT1可促進HIV複製，CRISPR/Cas9敲除MALAT1可顯著抑制HIV-LTR驅動的轉錄；機制上，MALAT1與PRC2抑制複合體中的組蛋白賴氨酸N-甲基轉移酶EZH2（enhancer of zeste homolog 2）結合，使其從HIV-LTR上解離，減弱EZH2對HIV-LTR區核小體組蛋白的H3K27me3表觀遺傳學修飾（抑制性），使HIV-LTR維持在活躍狀態，促進HIV轉錄；此外，與北京協和醫院教授李太生合作，發現抗逆轉錄病毒藥物治療可顯著降低HIV感染者外周血PBMC中MALAT1的表達，驗證MALAT1表達與HIV複製的正相關性。

圖示：MALAT1調節HIV複製的分子機制。MALAT1誘使抑制性的PRC2複合物從HIV啟動子LTR解離，通過減弱EZH2對HIV-LTR區核小體組蛋白的H3K27me3表觀遺傳學修飾，促進HIV轉錄和複製。

曲迪和孫瑋瑋為論文並列第一作者，王建華、侯煒和李太生為並列通訊作者。上海巴斯德所研究員金俠為該研究提出了建議；該研究得到國家基金委、中科院及科技部艾滋病和病毒性肝炎重大傳染病防治專項等的資助。

ABSTRACT：

Long noncoding RNAs (lncRNAs) may either repress or activate HIV-1 replication and latency; however, specific mechanisms for their action are not always clear. In HIV-1 infected CD4 T cells, we performed RNA-Sequencing (RNA-Seq) analysis and discovered an up-regulation of MALAT1 (metastasis-associated lung adenocarcinoma transcript 1), an lncRNA previously described in cancer cells that associate with cancer pathogenesis. Moreover, we found that MALAT1 promoted HIV-1 transcription and infection, as its knockdown by CRISPR/Cas9 markedly reduced the HIV-1 long terminal repeat (LTR)-driven gene transcription and viral replication. Mechanistically, through an association with chromatin modulator polycomb repressive complex 2 (PRC2), MALAT1 detached the core component enhancer of zeste homolog 2 (EZH2) from binding with HIV-1 LTR promoter, and thus removed PRC2 complex-mediated methylation of histone H3 on lysine 27 (H3K27me3) and relieved epigenetic silencing of HIV-1 transcription. Moreover, the reactivation of HIV-1 stimulated with latency reversal agents (LRAs) induced MALAT1 expression in latently infected cells. Successful combination antiretroviral therapy (cART) was accompanied by significantly diminished MALAT1 expression in patients, suggesting a positive correlation of MALAT1 expression with HIV-1 replication. Our data have identified MALAT1 as a promoter of HIV-1 transcription, and suggested that MALAT1 may be targeted for the development of new therapeutics.

1. Qu D,Sun WW,Li L,Ma L,Sun L,Jin X,Li T,Hou W,Wang JH.Long noncoding RNA MALAT1 releases epigenetic silencing of HIV-1 replication by displacing the polycomb repressive complex 2 from binding to the LTR promoter. Nucleic Acids Research.February 15,2019. gkz117.

https://doi.org/10.1093/nar/gkz117

2.中科院微生物所.上海巴斯德所等揭示長鏈非編碼RNA調控HIV複製新機制

http://www.cas.cn/syky/201902/t20190225_4680186.shtml

本期編輯：Annabella

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