Mechanistic studies on the unique set of accessory proteins encoded by the gamma 6 human papillomaviruses

乳头瘤病毒感染鳞状上皮组织，其复制生命周期与感染上皮组织的分化状态密切相关。 HPV 最初感染分裂中的基底上皮细胞，这些细胞位于上皮的底层。在那里，HPV 建立持续感染，病毒基因组与宿主细胞 DNA 一致复制。然而，感染性病毒后代的产生仅限于终末分化的上皮细胞。这些细胞生长停滞，因此不再产生支持 HPV 基因组合成所需的因子。 HPV 编码多达三种辅助蛋白：E5、E6 和 E7，它们对终末分化的上皮细胞进行重新编程，以支持大规模病毒基因组合成。 E5、E6 和 E7 蛋白的机制贡献仅针对一种特定的 HPV（HPV16）（α 属成员）进行了广泛研究。鉴于所有 HPV 都必须在终末分化、生长停滞的细胞中建立复制能力的环境才能产生病毒后代，因此可以合理地假设，从 HPV16 研究中获得的见解将适用于 440 多种系统发育不同的 HPV 中的大多数（如果不是全部）。然而，最近对 HPV β 属的研究表明，这是一个错误的假设。 β HPV 仅编码两种辅助蛋白：E6 和 E7。它们缺乏 E5，并且 E6 和 E7 蛋白的分子靶点和生物活性非常不同。与结合并靶向 p53 进行降解的 HPV16 E6 不同，β HPV E6 蛋白分别通过结合 MAML 和 SMAD 蛋白来抑制 NOTCH 和 TGF-β 信号传导。 γ 属 HPV 包括 300 多个成员，与 β HPV 类似，它们不编码 E5 蛋白。 γ HPV 几乎完全未经研究，因为大多数感染尚未与临床相关病变相关。然而，gamma 6 种的成员脱颖而出，因为与大多数感染皮肤上皮的 gamma HPV 不同，它们都是从肛门生殖道粘膜上皮中分离出来的。与 HPV16 类似，它们很可能通过性传播，并与医学相关的宫颈病变有关。此外，gamma 6 HPV 因其独特的基因组结构而脱颖而出。与所有其他 HPV 不同，gamma 6 HPV 没有 E6 蛋白，而是编码独特的微小疏水性跨膜蛋白，称为 E10。我们将确定 γ 6 HPV101 E10 和 E7 蛋白的生化靶点和生物活性。拟议的工作将提供令人着迷的见解，这对于 HPV 领域来说是全新的。这些研究将揭示 HPV101 E7 和 E10 蛋白如何合作以允许分化上皮细胞中的病毒生命周期，以及这如何可能导致宫颈病变。

Papillomaviruses infect squamous epithelial tissues, and their replicative life cycle is tightly linked to the differentiation status of the infected epithelial tissues. HPVs initially infect dividing basal epithelial cells, which populate the bottom layer of the epithelium. There, HPVs establish a persistent infection, and the viral genome replicates in concert with the host cell DNA. Production of infectious viral progeny, however, is restricted to terminally differentiated epithelial cells. These cells are growth-arrested and, hence, they no longer produce the factors that are necessary to support HPV genome synthesis. HPVs encode up to three accessory proteins, E5, E6, and E7, that reprogram terminally differentiated epithelial cells to support large scale viral genome synthesis. The mechanistic contributions of the E5, E6, and E7 proteins have been extensively studied only for one specific HPV, HPV16, a member of the alpha genus. Given that all HPVs have to establish a replication-competent milieu in terminally differentiated, growth-arrested cells to produce viral progeny, it has been reasonably assumed that the insights gained from studies with HPV16 would apply to most if not all of the more than 440 phylogenetically different HPVs. More recent studies with beta genus HPVs, however, have revealed that this was an erroneous assumption. The beta HPVs only encode two accessory proteins, E6 and E7. They lack E5s and the molecular targets and biological activities of the E6 and E7 proteins are quite distinct. Unlike HPV16 E6, which binds and targets p53 for degradation, the beta HPV E6 proteins inhibit NOTCH and TGF-beta signaling by binding to MAML and SMAD proteins, respectively. The gamma genus HPVs include over 300 members, and similar to the beta HPVs, they do not encode E5 proteins. Gamma HPVs are almost entirely unstudied because most infections have not been linked to clinically relevant lesions. The members of the gamma 6 species, however, stand out because, unlike most gamma HPVs that infect cutaneous epithelia, they have all been isolated from anogenital tract mucosal epithelia. Similar to HPV16, they are likely sexually transmitted and have been linked to medically relevant cervical lesions. Moreover, the gamma 6 HPVs stand out by their unique genome organization. Unlike all other HPVs, the gamma 6 HPVs have no E6 proteins but instead encode unique, tiny hydrophobic transmembrane proteins, designated E10. We will determine the biochemical targets and biological activities of the gamma 6 HPV101 E10 and E7 proteins. The proposed work will provide fascinating insights that will be entirely novel to the HPV field. The studies will reveal how the HPV101 E7 and E10 proteins cooperate to permit the viral lifecycle in differentiated epithelial cells and how this may result in cervical lesions.