HPV16-E6 associated hTERT promoter acetylation is E6AP dependent, increased in later passage cells and enhanced by loss of p300
HPV16-E6 associated hTERT promoter acetylation is E6AP dependent, increased in later passage cells and enhanced by loss of p300
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DOI：
10.1002/ijc.22064
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发表时间：
2006-10-15
影响因子：
6.4
通讯作者：
Klingelhutz, Aloysius J.
中科院分区：
文献类型：
--
作者：
James, Michael A.;Lee, John H.;Klingelhutz, Aloysius J.
来自高危HPV型的E6癌蛋白激活了人角质形成细胞中人端粒酶逆转录酶(HTERT)的转录。关于E6如何调控hTERT的研究涉及hTERT启动子中的E-box或X-box元件(Veldman等人，Proc Natl Acad Sci USA 2003；100：8211-14；oh等人，J Virol 2001；75：5559-66；Gewin等人，gene Dev 2004；18：2269-82)，但E6激活的机制仍有争议，且尚未很好地确定。在这里，我们证明了HPV-16E6对早期传代角质形成细胞hTERT表达和端粒酶活性的诱导与组蛋白H3在hTERT启动子上的乙酰化有关，依赖于E6相关蛋白(E6AP)，而不完全依赖于E-box或X-box元件。在培养中广泛传代的表达E6的细胞中，hTERT启动子的组蛋白乙酰化和hTERT转录活性进一步增加，发现只有内源性启动子才能发生，而外源hTERT启动子构建没有发生。然而，早期和晚期的端粒酶活性依赖于E6AP的表达，这意味着端粒酶活性继续依赖于E6功能。我们的结果表明，E6诱导hTERT启动子的乙酰化，但在传代后期E6表达细胞中端粒酶活性和组蛋白乙酰化的进一步增加不依赖于核心hTERT启动子的E6激活。我们还提供了证据，证明转录因子p300在E6表达的背景下是端粒酶激活和组蛋白乙酰化的潜在抑制因子。这些研究使我们深入了解了HPV永生化是如何导致hTERT上调的，并加深了我们对端粒酶在恶性转化过程中如何激活的理解。(C)2006年Wiley-Liss，Inc.
The E6 oncoprotein from high-risk HPV types activates human telomerase reverse transcriptase (hTERT) transcription in human keratinocytes. Studies on how E6 regulates hTERT have implicated E-box or X-box elements in the hTERT promoter (Veldman et al., Proc Natl Acad Sci USA 2003; 100:8211-14; Oh et al., J Virol 2001;75:5559-66; Gewin et al., Genes Dev 2004;18:2269-82), but the mechanism of activation by E6 is still controversial and not well defined. Here, we demonstrate that induction of both hTERT expression and telomerase activity by HPV-16 E6 in early passage keratinocytes is associated with acetylation of histone H3 at the hTERT promoter, is dependent on the E6 associated protein (E6AP) and is not exclusively reliant on E-box or X-box elements. Further increases in histone acetylation of the hTERT promoter and hTERT transcriptional activity in E6 expressing cells that had been passaged extensively in culture were found to occur only with the endogenous promoter and not with an exogenously introduced hTERT promoter construct. Telomerase activity at both early and late passages, however, was dependent on E6AP expression, implying a continued reliance on E6 function for telomerase activity. Our results demonstrate that E6 induces hTERT promoter acetylation, but that further increases in telomerase activity and histone acetylation in later passage E6 expressing cells are independent of E6 activation of the core hTERT promoter. We also provide evidence that the transcription factor p300 is a potential repressor of telomerase activation and histone acetylation in the context of E6 expression. These studies give insight into how immortalization by HPV results in upregulation of hTERT and furthers our understanding of how telomerase is activated during the process of malignant transformation. (c) 2006 Wiley-Liss, Inc.