Department of Otorhinolaryngology-Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.
mBio. 2022 Dec 20;13(6):e0203322. doi: 10.1128/mbio.02033-22. Epub 2022 Nov 8.
Human papillomavirus (HPV) E7 proteins bind to host cell proteins to facilitate virus replication. Interactions between HPV E7 and host cell proteins can also drive cancer progression. We hypothesize that HPV E7-host protein interactions specific for high-risk E7 contribute to the carcinogenic activity of high-risk HPV. The cellular protein ZER1 interacts with the E7 protein from HPV16, the genotype most frequently associated with human cancers. The HPV16 E7-ZER1 interaction is unique among HPV E7 tested to date. Other E7 proteins, even from closely related HPV genotypes, do not bind ZER1, which is a substrate specificity factor for a CUL2-RING ubiquitin ligase. In the present study, we investigated the contribution of ZER1 to the carcinogenic activity of HPV16 E7. First, we mapped the ZER1 binding site to specific residues on the C terminus of HPV16 E7. We showed that the mutant HPV16 E7 that cannot bind ZER1 is impaired in the ability to promote the growth of primary keratinocytes. We found that ZER1 and CUL2 contribute to, but are not required for, HPV16 E7 to degrade RB1. Cancer dependency data show that ZER1 is an essential gene in most HPV-positive, but not HPV-negative, cancer cell lines. Depleting ZER1 impaired the growth of primary keratinocytes expressing HPV16 E7 or HPV18 E7 and of HPV16-and HPV18-positive cervical cancer cell lines. Taken together, our work demonstrates that ZER1 contributes to HPV-mediated carcinogenesis and is essential for the growth of HPV-positive cells. HPV16 is highly carcinogenic and is the most predominant HPV genotype associated with human cancers. The mechanisms that underlie differences between high-risk HPV genotypes are currently unknown, but many of these differences are likely attributable to the activities of the oncogenic HPV proteins, including E7. The HPV E7 oncoprotein is essential for HPV-mediated carcinogenesis. A large number of HPV E7 targets have been identified. However, it is unclear which of these many interactions contributes to the carcinogenic activity of HPV E7. Here, we characterized the interaction between HPV16 E7 and the host cell protein ZER1, testing whether this genotype-specific interaction could enable some of the carcinogenic activity of HPV16 E7. We found that ZER1 binding contributes to the growth-promoting activity of HPV16 E7 and to the growth of HPV-positive cervical cancer cells. We propose that ZER1 makes an important contribution to HPV-mediated carcinogenesis.
人乳头瘤病毒（HPV）E7 蛋白与宿主细胞蛋白结合，以促进病毒复制。HPV E7 与宿主细胞蛋白的相互作用也可推动癌症进展。我们假设，高危型 HPV E7 特有的 HPV E7-宿主蛋白相互作用有助于高危型 HPV 的致癌活性。细胞蛋白 ZER1 与 HPV16 的 E7 蛋白相互作用，HPV16 是与人类癌症最相关的基因型。在迄今为止测试的 HPV E7 中，HPV16 E7-ZER1 相互作用是独特的。其他 E7 蛋白，即使来自密切相关的 HPV 基因型，也不与 ZER1 结合，ZER1 是一种 CUL2-RING 泛素连接酶的底物特异性因子。在本研究中，我们研究了 ZER1 对 HPV16 E7 致癌活性的贡献。首先，我们将 ZER1 结合位点映射到 HPV16 E7 的 C 端的特定残基上。我们发现，不能与 ZER1 结合的 HPV16 E7 突变体在促进原代角质形成细胞生长的能力上受损。我们发现 ZER1 和 CUL2 有助于但不是必需的 HPV16 E7 降解 RB1。癌症依赖性数据表明，ZER1 是大多数 HPV 阳性但不是 HPV 阴性癌症细胞系中的必需基因。耗尽 ZER1 会损害表达 HPV16 E7 或 HPV18 E7 的原代角质形成细胞以及 HPV16 和 HPV18 阳性宫颈癌细胞系的生长。总之，我们的工作表明 ZER1 有助于 HPV 介导的致癌作用，并且是 HPV 阳性细胞生长所必需的。HPV16 具有高度致癌性，是与人类癌症最相关的主要 HPV 基因型。目前尚不清楚高危型 HPV 基因型之间差异的基础机制，但其中许多差异可能归因于致癌 HPV 蛋白的活性，包括 E7。HPV E7 癌蛋白是 HPV 介导的致癌作用所必需的。已经确定了大量 HPV E7 靶标。然而，尚不清楚这些相互作用中的哪一种有助于 HPV E7 的致癌活性。在这里，我们描述了 HPV16 E7 与宿主细胞蛋白 ZER1 之间的相互作用，检验了这种基因型特异性相互作用是否可以赋予 HPV16 E7 的部分致癌活性。我们发现 ZER1 结合有助于 HPV16 E7 的促生长活性和 HPV 阳性宫颈癌细胞的生长。我们提出 ZER1 对 HPV 介导的致癌作用有重要贡献。
