Transforming Mechanisms of Merkel Cell Polyoma Virus

描述（由申请人提供）：驱动本研究申请的总体假设是默克尔细胞多瘤病毒（MCPyV）小T抗原（ST）结合Myc同源物和Tip60/TRRAP复合体是病毒介导的默克尔细胞癌（MCC）的肿瘤发生所必需的。我的实验室在2种不同MCC细胞系的MCPyV ST的大规模免疫沉淀中鉴定了LMyc， NMyc， Max以及整个15组分的Tip60/TRRAP复合物。鉴于已知Myc在肿瘤发生中的作用以及Tip60/TRRAP复合体在Myc依赖基因表达中的作用，我们提出ST结合Myc和Tip60/TRRAP复合体是MCPyV转化和肿瘤发生所必需的。具体目的：(1)评估MCPyV在人成纤维细胞和小鼠原代默克尔细胞中的细胞转化潜力。(2)确定MCPyV ST如何与Myc和Tip60/TRRAP复合物结合。鉴定ST中与Myc和Tip60/TRRAP复合物结合所需的结构域和残基。确定与MCPyV st结合需要Tip60/TRAPP复合物的哪些组分，确定MCPyV介导的转化的维持是否依赖于完整的Tip60/TRRAP复合物。(3)评估Myc和Tip60/TRRAP复合物对MCPyV转化和肿瘤发生的贡献。确定显性阴性Myc物种或特异性Myc同源物的缺失是否可以在体外和体内抑制MCPyV转化。确定ST是否以Myc或Tip60/TRRAP复合体依赖的方式被募集到染色质上。的意义。了解MCPyV如何促进MCC发展的一个关键障碍是缺乏对MCPyV大T抗原（LT）或ST在从典型多瘤病毒、SV40和小鼠多瘤病毒转化中的作用是否以及如果有，如何不同的认识。此外，目前还不清楚为什么默克尔细胞似乎特别容易被MCPyV转化，因为没有其他人类肿瘤含有整合的MCPyV病毒基因组的报道。我的研究实验室最近发现，MCPyV ST在细胞中与Myc和Tip60/TRRAP复合物特异性结合，该项目旨在解决这些关键障碍。

DESCRIPTION (provided by applicant): The overall hypothesis that drives this research application is that Merkel cell polyomavirus (MCPyV) small T antigen (ST) binding to Myc homologues and the Tip60/TRRAP complex is required for viral mediated oncogenesis of Merkel cell carcinoma (MCC). My laboratory identified LMyc, NMyc, Max as well as the entire, 15-component, Tip60/TRRAP complex in a large-scale immunoprecipitation for MCPyV ST from 2 different MCC cell lines. Given the known role of Myc in oncogenesis and the Tip60/TRRAP complex in Myc dependent gene expression, we propose that ST binding to Myc and the Tip60/TRRAP complex is required for MCPyV transformation and tumorigenesis. Specific Aims: (1) Assess the cellular transforming potential of MCPyV in human fibroblasts and primary mouse Merkel cells. (2) Determine how MCPyV ST binds to Myc and the Tip60/TRRAP complex. Identify domains and residues in ST required for binding to Myc and the Tip60/TRRAP complex. Determine what components of the Tip60/TRAPP complex are required for binding to MCPyV ST. Determine whether the maintenance of MCPyV-mediated transformation is dependent on an intact Tip60/TRRAP complex. (3) Assess the contribution of Myc and the Tip60/TRRAP complex to MCPyV transformation and tumorigenesis. Determine if a dominant negative Myc species or loss of specific Myc homologues can inhibit MCPyV transformation in vitro and in vivo. Determine whether ST is recruited to chromatin in a Myc or Tip60/TRRAP complex dependent manner. Significance. A critical barrier to understanding how MCPyV contributes to the development of MCC is the lack of appreciation of whether and, if so, how MCPyV large T antigen (LT) or ST differ in their contributions to transformation from the canonical polyomaviruses, SV40 and mouse polyomavirus. Furthermore, it is not clear why Merkel cells seem to be uniquely susceptible to transformation by MCPyV since no other human tumor has been reported to contain integrated MCPyV viral genome. This proposed project addresses these critical barriers by building on a recent discovery from my research laboratory that MCPyV ST binds specifically in cells to Myc and the Tip60/TRRAP complex.