Control of SnoN Activity by SUMO modification

描述（由申请方提供）：SnoN和c-Ski是核原癌基因蛋白，具有能够影响细胞增殖并启动终末骨骼肌分化的不寻常特性，其中细胞退出细胞周期。据认为，Ski家族蛋白通过拮抗TGF-β信号传导的生长抑制功能来实现其转化能力。SnoN在诱导转化和肌生成方面不如c-Ski有效，并且关于如何控制弱性质知之甚少。因此，SnoN和Ski对细胞转化和分化的矛盾作用尚未完全理解。在本申请中，我们将重点研究SnoN是如何通过SUMO修饰来调节的。我们的假设是SUMO化控制SnoN在转化和细胞分化中的生物学活性。提出了两个具体目标：1。研究SnoN SUMO化的分子相互作用和要求。我们将从生物化学的角度研究SnoN的SUMO修饰。将测试潜在的SUMO E3连接酶在SnoN SUMO化中的作用，并分析其与SnoN的相互作用。还将研究SnoN SUMO化发生的亚细胞位置。2.阐明SnoN SUMO化在细胞增殖和成肌分化中的生理功能。将分析SnoN蛋白在各种细胞增殖或分化条件下的SUMO化，以确定SnoN的SUMO化状态与其细胞调节活性之间是否存在相关性。功能获得或功能丧失方法也将用于阐明SnoN SUMO化在细胞转化和肌分化中的功能。将确定SnoN功能改变的分子基础。目前的建议将开辟一个新的研究领域，如何通过翻译后修饰调节Ski家族蛋白的活动。特别是SUMO修饰在SnoN蛋白功能调控中的作用的研究将有助于我们理解SnoN/c-Ski在细胞增殖和分化的协同调控中的生物学作用。最后，这些结果也可能为合理设计预防和治疗癌症和肌肉骨骼疾病的新治疗方法提供基础。

DESCRIPTION (provided by applicant): SnoN and c-Ski are nuclear proto-oncogenic proteins that have the unusual property of being able to affect cellular proliferation and also initiate terminal skeletal muscle differentiation, in which cells withdraw from the cell cycle. It is thought that the Ski family proteins achieve their transforming ability by antagonizing the growth inhibitory functions of TGF-b signaling. SnoN is less potent than c-Ski in inducing transformation and myogenesis, and little is known about how the weak property is controlled. Thus, the paradoxical effect of SnoN and Ski on cell transformation and differentiation has not been completely understood. In this application, we will focus our study on how SnoN is regulated by SUMO modification. Our hypothesis is that SUMOylation controls the biological activities of SnoN in transformation and cell differentiation. Two specific aims are proposed: 1. Investigate the molecular interactions and requirements of SnoN SUMOylation. We will examine biochemically the SUMO modification of SnoN. Potential SUMO E3 ligases will be tested for their role in SnoN SUMOylation, and their interactions with SnoN will be analyzed. Subcellular location where SnoN SUMOylation occurs will also be investigated. 2. Elucidate the physiological functions of SnoN SUMOylation in cell proliferation and myogenic differentiation. SUMOylation of SnoN proteins under various conditions for cell proliferation or differentiation will be analyzed to determine whether there is a correlation between the SUMOylation status of SnoN and its activity in cell regulation. Gain-of-function or loss-of-function approaches will also be used to elucidate the functions of SnoN SUMOylation in cell transformation and myo-differentiation. Molecular basis for the altered functions of SnoN will be determined. The current proposal will open up a new area of research on how the activities of Ski family proteins are regulated by post-translational modification. Particularly, the study on the role of SUMO modification in SnoN protein function regulation will contribute to our understanding of the biology of SnoN/c-Ski in the coordinated regulation of cell proliferation and differentiation. Finally, the results may also provide a foundation for the rational design of novel therapeutic approaches for prevention and treatment of cancer and musculoskeletal diseases.