Interaction of NCOR/SMRT Repressor Complexes with Papillomavirus E8^E2C Proteins Inhibits Viral Replication.
Interaction of NCOR/SMRT Repressor Complexes with Papillomavirus E8^E2C Proteins Inhibits Viral Replication.
复制标题
NCOR/SMRT抑制剂复合物与乳头瘤病毒E8^E2C蛋白的相互作用抑制病毒复制。
DOI：
10.1371/journal.ppat.1005556
复制
发表时间：
2016-04
期刊：
影响因子：
6.7
通讯作者：
Stubenrauch F
中科院分区：
文献类型：
--
作者：
Dreer M;Fertey J;van de Poel S;Straub E;Madlung J;Macek B;Iftner T;Stubenrauch F
感染高危人乳头瘤病毒(HR-HPV)，如HPV16和HPV31，可导致无生殖器和口咽癌，而贝塔属的HPV类型与非黑色素瘤皮肤癌的发展有关。在未分化的细胞中，HPV以低拷贝数的核质粒形式复制。HPV16和31突变株表明，这些病毒表达一种E8^E2C蛋白，该蛋白负向调节基因组复制。E8 E2C与病毒复制激活因子E2共享DNA结合和二聚化结构域(E2C)，E8结构域取代了E2的复制/转录激活结构域。HR-HPV E8结构域是抑制病毒转录和由病毒E1和E2蛋白介导的病毒来源复制所必需的。我们现在发现，E8^E2C也限制了HPV1和HPV8在正常人角质形成细胞中的复制。蛋白质组学分析证实，所有NCoR/SMRT辅阻遏子复合体成分(HDAC3、GPS2、NCoR、SMRT、TBL1和TBLR1)都是HPV16和31 E8、E2C蛋白的共沉淀宿主细胞蛋白。免疫共沉淀和共定位实验表明，NCoR/SMRT组分与HPV1、8、16和31个E8、E2C蛋白以E8依赖的方式相互作用。SiRNA敲除实验证实，NCoR/SMRT组分在E8、E2C蛋白抑制转录和HPV起源复制过程中起关键作用。此外，显性负性NCoR片段仅能激活HPV16和31wt的转录和复制，而不能激活编码NCoR/SMRT结合缺陷E8、E2C蛋白的突变基因组的转录和复制。综上所述，我们的数据表明，E8、E2C的抑制功能在HPV中是高度保守的，它是由依赖于E8的与NCoR/SMRT复合体的相互作用所介导的。我们的数据还首次表明，NCoR/SMRT复合体不仅参与抑制细胞和病毒的转录，而且还参与控制HPV起源的复制。人类乳头瘤病毒(HPV)已被证明可导致无生殖道癌和口咽癌，也与非黑色素瘤皮肤癌有关。HPV有一个两阶段的复制周期：在未分化的角质形成细胞中，只能观察到低水平的基因组复制而不产生病毒，而在分化的角质形成细胞中，可以观察到高水平的基因组复制和病毒产生。以前的研究表明，一些HPV编码E8^E2C蛋白，限制了未分化细胞的基因组复制。我们现在证明了来自不同HPV类型的E8、E2C蛋白与NCoR/SMRT辅阻遏子复合体相互作用，以限制病毒转录和基因组复制。虽然已知NCoR/SMRT复合体介导多种宿主转录因子的转录抑制功能，但这是第一个证据表明NCoR/SMRT蛋白也参与抑制病毒起源的复制。
Infections with high-risk human papillomaviruses (HR-HPV) such as HPV16 and 31 can lead to ano-genital and oropharyngeal cancers and HPV types from the beta genus have been implicated in the development of non-melanoma skin cancer. HPV replicate as nuclear extrachromosomal plasmids at low copy numbers in undifferentiated cells. HPV16 and 31 mutants have indicated that these viruses express an E8^E2C protein which negatively regulates genome replication. E8^E2C shares the DNA-binding and dimerization domain (E2C) with the essential viral replication activator E2 and the E8 domain replaces the replication/transcription activation domain of E2. The HR-HPV E8 domain is required for inhibiting viral transcription and the replication of the viral origin mediated by viral E1 and E2 proteins. We show now that E8^E2C also limits replication of HPV1, a mu-PV and HPV8, a beta-PV, in normal human keratinocytes. Proteomic analyses identified all NCoR/SMRT corepressor complex components (HDAC3, GPS2, NCoR, SMRT, TBL1 and TBLR1) as co-precipitating host cell proteins for HPV16 and 31 E8^E2C proteins. Co-immunoprecipitation and co-localization experiments revealed that NCoR/SMRT components interact with HPV1, 8, 16 and 31 E8^E2C proteins in an E8-dependent manner. SiRNA knock-down experiments confirm that NCoR/SMRT components are critical for both the inhibition of transcription and HPV origin replication by E8^E2C proteins. Furthermore, a dominant-negative NCoR fragment activates transcription and replication only from HPV16 and 31 wt but not from mutant genomes encoding NCoR/SMRT-binding deficient E8^E2C proteins. In summary, our data suggest that the repressive function of E8^E2C is highly conserved among HPV and that it is mediated by an E8-dependent interaction with NCoR/SMRT complexes. Our data also indicate for the first time that NCoR/SMRT complexes not only are involved in inhibiting cellular and viral transcription but also in controlling the replication of HPV origins. Human papillomaviruses (HPV) have been shown to cause ano-genital and oropharyngeal cancers and have been also implicated in non-melanoma skin cancer. HPV have a two-stage replication cycle: in undifferentiated keratinocytes only a low level of genome replication without virus production can be observed whereas in differentiated keratinocytes high-level genome replication and virus production takes place. Previous studies have suggested that some HPV encode an E8^E2C protein that limits genome replication in undifferentiated cells. We now demonstrate that E8^E2C proteins from phylogenetically diverse HPV types interact with NCoR/SMRT corepressor complexes to limit viral transcription and genome replication. While NCoR/SMRT complexes are known to mediate the transcription repression functions of a wide variety of host transcription factors, this is the first evidence that NCoR/SMRT proteins also are involved in the repression of the replication of viral origins.