Changes in the Cornified Cell Envelope in HPV Infection

描述(申请人提供)：HPV在细胞水平的传播机制尚不清楚。角质形成细胞是HPV感染的靶细胞。这些细胞通常退出细胞周期，经历分化过程，包括表达成为角化细胞膜(CCE)组成部分的蛋白质。洛丽蛋白、总蛋白、富含小脯氨酸的蛋白(SPRs)、细胞角蛋白和其他蛋白质是共价交联的，从而组成CCE。分化的终点是一层扁平的、持久的、去核的CCE，它为宿主提供屏障保护。HPV感染不会导致细胞溶解，病毒粒子从感染的角质形成细胞中逃逸的机制尚不清楚。CCE在其正常、持久的状态下可能会阻碍病毒粒子的释放。我们推测，有缺陷的CCE会促进病毒粒子的释放。我们的研究支持这一假设。我们发现HPV11感染会导致CCES的异常，而HPV11感染组织中脱屑、角化的细胞是感染的有效传递者。我们还表明，HPV11EL、E4蛋白在体内与CCE有关。我们对HPV11感染对CCE的影响的研究表明，在HPV11感染的上皮细胞中，Ioricrin的数量显著减少，而SPR3的表达丰富。我们在完全分化的上皮细胞上进行的研究表明，HPV11基因产物导致了CCE的缺陷。此外，我们最近的研究表明，HPV11感染会降低Ioricrin的转录。HPV基因产物对CCE的联合作用可能有助于病毒粒子的逃逸，从而提高HPV的传播效率。在目前的提案中，我们将检验HPV11导致CCE缺陷的假设，并且这些缺陷可以归因于E1、E4和E2蛋白的影响。为了验证这一假说，我们将1)确定EL^E4蛋白是TGase底物还是这些酶的抑制剂；2)分析EL^E4蛋白对CCE的组成和生物物理特性的影响；3)检测E2对CCE蛋白Ioricrin和小的富含Pro的蛋白3表达的影响。

DESCRIPTION (provided by applicant): The mechanism of HPV transmission at the cellular level is poorly understood. Keratinocytes are the target cells for HPV infection. These cells normally exit the cell cycle and undergo the process of differentiation, including expression of proteins that become components of the cornified cell envelope (CCE). Loricrin, involucrin, small proline rich proteins (SPRs), cytokeratins, and other proteins are covalently cross-linked to make up the CCE. The endpoint of differentiation is a layer of flattened, durable, enucleated CCEs that provides the host with barrier protection. HPV infection does not induce cell lysis, and the mechanism of virion escape from infected keratinocytes is not known. The CCE in its normal, durable state would likely hinder virion release. We theorized that a defective CCE would facilitate release of virions. Our studies support this hypothesis. We have shown that HPV 11 infection induces abnormalities of CCEs, and that desquamated, cornified cells from HPV 11 infected tissue are effective transmitters of infection. We have also shown that the HPV 11 El^E4 protein is associated in vivo with the CCE. Our studies of the effects of HPV 11 infection on the CCE demonstrate a markedly reduced amount of Ioricrin and an abundance of SPR3 in HPV 11-infected epithelium. Our studies, performed on fully differentiated epithelium, suggest that HPV 11 gene products cause the defects in the CCE. In addition, our recent studies show that HPV 11 infection reduces Ioricrin transcription. The combined effects of HPV gene products on the CCE may facilitate the escape of virions, and thus increase the efficiency of HPV transmission. In the current proposal, we will test the hypothesis that HPV 11 induces defects of the CCE, and that these defects can be attributed to the effects of the El^E4 and E2 proteins. To test the hypothesis, we will 1) determine if the El^E4 protein is a TGase substrate or an inhibitor of these enzymes; 2) analyze the effects of El^E4 proteins on the composition and biophysical characteristics of CCEs, and 3) examine of the effects of the E2 on expression of the CCE proteins Ioricrin and small proline rich protein 3.