HUMAN PAPILLOMAVIRUS TYPE 31B LATE GENE-EXPRESSION IS REGULATED THROUGH PROTEIN-KINASE C-MEDIATED CHANGES IN RNA PROCESSING
HUMAN PAPILLOMAVIRUS TYPE 31B LATE GENE-EXPRESSION IS REGULATED THROUGH PROTEIN-KINASE C-MEDIATED CHANGES IN RNA PROCESSING
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DOI：
10.1128/jvi.69.6.3381-3388.1995
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发表时间：
1995-06-01
影响因子：
5.4
通讯作者：
LAIMINS, LA
中科院分区：
文献类型：
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作者：
HUMMEL, M;LIM, HB;LAIMINS, LA
人乳头瘤病毒 (HPV) 衣壳基因 L1 和 L2 的表达，以及病毒 DNA 和病毒体组装的扩增发生在体内受感染的复层鳞状上皮的终末分化层中。这些过程可以在实验室中通过使用器官型或筏培养物进行复制。当含有高危 HPV 31b 型游离型拷贝的 CIN612 细胞在筏培养物中分化时，表达编码早期基因 E1（布尔 AND）E4 和 E5 的转录本被诱导，这些转录本在位于 E7 开放阅读框中间的分化依赖性 P742 启动子处启动。将筏培养物暴露于蛋白激酶 C 激活剂（例如佛波酯），会进一步诱导晚期基因表达以及病毒粒子组装。在本研究中，我们研究了蛋白激酶C激活剂诱导晚期基因表达的机制，发现主要的L1转录本是由双顺反子E1（布尔AND）E4，L1 RNA编码的，该RNA在分化依赖性启动子P742处启动，还从早期区域启动子P97观察到含L1的RNA的额外低水平表达，发现主要的L2转录本由E1（布尔AND）E4，ES编码， L2、L1 RNA 也在早期区域启动，可能在分化特异性启动子 P742 处启动。虽然早期和晚期RNA被发现由相同的启动子表达，但它们在剪接和多聚腺苷酸化位点的利用上有所不同，用蛋白激酶C激活剂处理的Raft培养物诱导了晚期基因的表达，但没有观察到在P742启动子处启动的早期RNA的丰度发生变化。因此，晚期基因表达的增加可能是由于RNA加工或稳定性的变化，而不是由于P742转录速率的增加。因此，HPV 晚期基因表达的调节发生在两个水平上：P742 启动子的分化依赖性诱导（可以通过筏培养物中的生长在体外模拟）和转录后变化（可以通过蛋白激酶 C 的激活诱导）。这些转录后变化可能通过剪接因子的失活或下调来发生，剪接因子抑制晚期区域聚腺苷酸化位点的使用，从而导致晚期区域转录物的稳定性增加。
Expression of the human papillomavirus (HPV) capsid genes, L1 and L2, as well as amplification of viral DNA and virion assembly occur in the terminally differentiated layers of infected stratified squamous epithelium in vivo, These processes can be duplicated in the laboratory through the use of organotypic or raft cultures, When CIN612 cells, which contain episomal copies of the high-risk HPV type 31b, are allowed to differentiate in raft cultures, the expression of transcripts encoding the early genes E1(boolean AND) E4 and E5 is induced, These transcripts are initiated at the differentiation-dependent P742 promoter located in the middle of the E7 open reading frame. Exposure of raft cultures to activators of protein kinase C, such as phorbol esters, results in the further induction of late gene expression as well as virion assembly. In this study, we have investigated the mechanism by which activators of protein kinase C induce late gene expression, The major L1 transcript was found to be encoded by a bicistronic E1(boolean AND) E4, L1 RNA which initiated at the differentiation-dependent promoter P742, Additional low-level expression of L1-containing RNAs was also observed from the early-region promoter, P97, The major L2 transcripts were found to be encoded by E1(boolean AND) E4, ES, L2, L1 RNAs which were also initiated in the early region, probably at the differentiation-specific promoter P742. While early and late RNAs were found to be expressed from the same promoter, they differed in utilization of splicing and polyadenylation sites, Raft cultures treated with activators of protein kinase C induced expression of late genes, but no change in the abundance of early RNAs initiated at the P742 promoter was observed, Thus, the increase in late gene expression was likely due to changes in RNA processing or stabilization rather than an increase in the rate of transcription from P742. Regulation of HPV late gene expression therefore occurs at two levels: differentiation-dependent induction of the P742 promoter, which can be mimicked in vitro by growth in raft cultures, and posttranscriptional changes that can be induced by activation of protein kinase C. These posttranscriptional changes may occur through inactivation or down-regulation of splicing factors which inhibit use of the late region polyadenylation site, resulting in increased stability of late region transcripts.