McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America.
Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States of America.
PLoS Pathog. 2023 Apr 10;19(4):e1011215. doi: 10.1371/journal.ppat.1011215. eCollection 2023 Apr.
Human papillomaviruses (HPVs) contribute to approximately 5% of all human cancers. Species-specific barriers limit the ability to study HPV pathogenesis in animal models. Murine papillomavirus (MmuPV1) provides a powerful tool to study the roles of papillomavirus genes in pathogenesis arising from a natural infection. We previously identified Protein Tyrosine Phosphatase Non-Receptor Type 14 (PTPN14), a tumor suppressor targeted by HPV E7 proteins, as a putative cellular target of MmuPV1 E7. Here, we confirmed the MmuPV1 E7-PTPN14 interaction. Based on the published structure of the HPV18 E7/PTPN14 complex, we generated a MmuPV1 E7 mutant, E7K81S, that was defective for binding PTPN14. Wild-type (WT) and E7K81S mutant viral genomes replicated as extrachromosomal circular DNAs to comparable levels in mouse keratinocytes. E7K81S mutant virus (E7K81S MmuPV1) was generated and used to infect FoxN/Nude mice. E7K81S MmuPV1 caused neoplastic lesions at a frequency similar to that of WT MmuPV1, but the lesions arose later and were smaller than WT-induced lesions. The E7K81S MmuPV1-induced lesions also had a trend towards a less severe grade of neoplastic disease. In the lesions, E7K81S MmuPV1 supported the late (productive) stage of the viral life cycle and promoted E2F activity and cellular DNA synthesis in suprabasal epithelial cells to similar degrees as WT MmuPV1. There was a similar frequency of lateral spread of infections among mice infected with E7K81S or WT MmuPV1. Compared to WT MmuPV1-induced lesions, E7K81S MmuPV1-induced lesions had a significant expansion of cells expressing differentiation markers, Keratin 10 and Involucrin. We conclude that an intact PTPN14 binding site is necessary for MmuPV1 E7's ability to contribute to papillomavirus-induced pathogenesis and this correlates with MmuPV1 E7 causing a delay in epithelial differentiation, which is a hallmark of papillomavirus-induced neoplasia.
人乳头瘤病毒（HPV）约占所有人类癌症的 5%。物种特异性障碍限制了在动物模型中研究 HPV 发病机制的能力。鼠乳头瘤病毒（MmuPV1）为研究乳头瘤病毒基因在自然感染引起的发病机制中的作用提供了强有力的工具。我们之前确定了蛋白酪氨酸磷酸酶非受体型 14（PTPN14），它是 HPV E7 蛋白靶向的肿瘤抑制因子，是 MmuPV1 E7 的一个潜在的细胞靶标。在这里，我们证实了 MmuPV1 E7-PTPN14 相互作用。根据已发表的 HPV18 E7/PTPN14 复合物结构，我们生成了一个 MmuPV1 E7 突变体 E7K81S，该突变体不能与 PTPN14 结合。野生型（WT）和 E7K81S 突变病毒基因组以可比较的水平作为染色体外环状 DNA 在小鼠角质形成细胞中复制。生成了 E7K81S 突变病毒（E7K81S MmuPV1）并用于感染 FoxN/Nude 小鼠。E7K81S MmuPV1 引起的肿瘤病变频率与 WT MmuPV1 相似，但病变出现较晚，且小于 WT 诱导的病变。E7K81S MmuPV1 诱导的病变也呈现出肿瘤疾病严重程度降低的趋势。在病变中，E7K81S MmuPV1 支持病毒生命周期的晚期（产毒）阶段，并以类似于 WT MmuPV1 的程度促进 E2F 活性和细胞 DNA 在基底上层上皮细胞中的合成。感染 E7K81S 或 WT MmuPV1 的小鼠之间的感染横向传播频率相似。与 WT MmuPV1 诱导的病变相比，E7K81S MmuPV1 诱导的病变中表达分化标志物角蛋白 10 和内披蛋白的细胞明显扩张。我们得出结论，完整的 PTPN14 结合位点是 MmuPV1 E7 促进乳头瘤病毒发病机制的必要条件，这与 MmuPV1 E7 导致上皮分化延迟相关，这是乳头瘤病毒诱导的肿瘤发生的一个标志。
