Changes in the Cornified Cell Envelope in HPV Infection

描述（由申请人提供）：HPV在细胞水平传播的机制知之甚少。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并经历分化过程，包括表达成为皮质细胞包膜（CCE）组分的蛋白质。兜甲蛋白、外皮蛋白、小的富含脯氨酸的蛋白质（SPR）、细胞角蛋白和其它蛋白质共价交联以构成CCE。分化的终点是一层扁平、耐用、去核的CCE，为宿主提供屏障保护。HPV感染不诱导细胞溶解，并且病毒体从感染的角质形成细胞逃逸的机制尚不清楚。处于正常、持久状态的CCE可能会阻碍病毒粒子的释放。我们推测，有缺陷的CCE将促进病毒体的释放。我们的研究支持这一假设。我们已经表明，HPV 11感染诱导异常的CCE，和脱落，从HPV 11感染的组织中的角质细胞是有效的传播感染。我们还表明，HPV 11 E1-E4蛋白在体内与CCE相关。我们对HPV 11感染对CCE的影响的研究表明，在HPV 11感染的上皮中，Ioricrin的量显著减少，SPR 3丰富。我们对完全分化上皮进行的研究表明，HPV 11基因产物导致CCE中的缺陷。此外，我们最近的研究表明，HPV 11感染减少Ioricrin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，从而增加HPV传播的效率。在当前的提议中，我们将测试HPV 11诱导CCE缺陷的假设，并且这些缺陷可以归因于E1-E4和E2蛋白的作用。为了检验该假设，我们将1）确定E1-E4蛋白是TGase底物还是这些酶的抑制剂; 2）分析E1-E4蛋白对CCE的组成和生物物理特性的影响，以及3）检查E2对CCE蛋白碘甲氨酸和小脯氨酸富集蛋白3的表达的影响。

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.