2011年1月20日,，國際學(xué)術(shù)雜志 PLoS ONE 在線發(fā)表了上海巴斯德研究所藍(lán)柯研究組關(guān)于腫瘤皰疹病毒--卡波濟肉瘤病毒（Kaposi’s Sarcoma associated herpesvirus,，KSHV）周期調(diào)控研究的最新成果,。該研究通過利用不同于之前的實驗系統(tǒng)，驗證了其他研究組報導(dǎo)的miR-K12-9能夠下調(diào)RTA的表達,。該研究還報導(dǎo)了一個新的KSHV編碼miRNA能夠通過直接抑制裂解期主要調(diào)控基因RTA，并影響RTA對下游裂解期基因和病毒粒子復(fù)制來維持病毒潛伏感染狀態(tài),。
KSHV是一種重要的人類腫瘤病毒，它能夠引起卡波濟肉瘤（KS）,、原發(fā)性滲出性淋巴瘤（PEL）和部分多中心性卡斯特曼?。∕CD）等惡性腫瘤。自從KSHV發(fā)現(xiàn)以來,，潛伏-裂解周期調(diào)控就成為國際研究熱點。
博士研究生林先志等在藍(lán)柯研究員指導(dǎo)下,，通過構(gòu)建含RTA3’UTR的報告基因，對所有KSHV編碼的pre-miRNA表達質(zhì)粒進行篩選,，發(fā)現(xiàn)KSHV編碼的多個miRNA能夠下調(diào)報告基因的表達,。其中miR-K12-9和miR-K12-7對報告基因的下調(diào)在不同細(xì)胞系中重復(fù)驗證。RTA3’UTR中miRNA靶位點突變實驗和miRNA特異抑制劑揭示miR-K12-7對報告基因的下調(diào)作用是由其產(chǎn)生的miR-K12-7-5p來實現(xiàn)的,。在KSHV陽性細(xì)胞系中過表達miR-K12-7能夠下調(diào)RTA蛋白水平的表達,，卻不能下調(diào)其mRNA水平,，說明miR-K12-7對RTA的抑制發(fā)生在翻譯水平上,。進一步實驗表明,，miR-K12-7不僅能夠下調(diào)RTA的表達，還能下調(diào)RTA下游裂解期基因的表達,，并對病毒粒子的產(chǎn)生有抑制作用,。
該研究得到國家973計劃、國家自然科學(xué)基金、中國科學(xué)院“百人計劃”和上海浦江人才計劃科研開發(fā)（A類）的資助,。（生物谷Bioon.com）
生物谷推薦原文出處：
PLoS ONE 6(1): e16224. doi:10.1371/journal.pone.0016224
miR-K12-7-5p Encoded by Kaposi's Sarcoma-Associated Herpesvirus Stabilizes the Latent State by Targeting Viral ORF50/RTA
Xianzhi Lin1, Deguang Liang1, Zhiheng He1, Qiang Deng1, Erle S. Robertson2, Ke Lan1*
1 Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China, 2 Department of Microbiology and the Abramson Comprehensive Cancer Center, University of Pennsylvania Medical School, Philadelphia, Pennsylvania, United States of America
Abstract
Seventeen miRNAs encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) have been identified and their functions have begun to be characterized. Among these miRNAs, we report here that miR-K12-7 directly targets the replication and transcription activator (RTA) encoded by open reading frame 50. We found that miR-K12-7 targeted the RTA 3′ untranslated region (RTA3′UTR) in a seed sequence-dependent manner. miR-K12-7-5p derived from miR-K12-7 mediates the inhibition of RTA expression, and the mutation of the seed match site totally abrogated the inhibitory effect of miR-K12-7 on RTA3′UTR. The inhibition of RTA expression by miR-K12-7 was further confirmed in the latently KSHV-infected 293/Bac36 cell line through transient transfection of miR-K12-7 expression plasmid or specific inhibitor of miR-K12-7-5p, respectively. The transient transfection of miR-K12-7 into 293/Bac36 cells reduced RTA expression and the expression of the downstream early genes regulated by RTA, and also the production of progeny virus was significantly reduced after treatment with chemical inducers. Our study revealed that another miRNA, miR-K12-7-5p, targets the viral immediate early gene RTA and that this miRNA contributes to the maintenance of viral latency.
