K-Ras sumoylation in cell proliferation and transformation

摘要 RAS蛋白是一种GTP酶，可以激活多个信号级联，从而调节细胞 生存、增殖、迁移和分化。几乎所有的RAS蛋白都受 已知的翻译后修饰，包括法尼化、棕榈酰化、磷酸化， 泛素化和乙酰化。然而，目前仍不清楚RAS蛋白是否被修饰 通过相扑化。我们最近发现，所有三种形式的RAS蛋白都是SUMO3修饰的。 我们的进一步研究表明，赖氨酸42(K42)是苏莫化的主要残基，而 PIAS、γ和MEKK1是对RAS求和的候选E3连接酶。相扑化是至关重要的 激活K-RAS及其下游信号。此外，我们还发现了一系列 在体外和体内以相扑结合为靶点的相扑E1抑制剂。先导化合物 27A和SB-264能有效地抑制总合作用，但不能抑制泛素化或去甲基化。值得注意的是， 这些化合物表现出很好的生物活性，可以杀死转化的胰腺细胞 甘氨酸12或甘氨酸13处的K-RAS突变并抑制其迁移。考虑到 苏莫化在控制关键细胞调节因子功能中的作用及K-蛋白的首要重要性 Ras在细胞增殖和转化中的作用，我们假设苏莫化促进K-Ras 相扑调节通路是开发抗病毒药物的极佳靶点。 抗癌药物。为了检验这一假设的有效性，本文提出了三个具体目标。我们会 确定和甲基化调节K-RAS活化的机制，阐明 控制K-RAS相扑甲基化的调控网络，并研究相扑E1的疗效 抑制临床前小鼠模型胰腺癌生长增殖的抑制剂。 K-RAS苏莫化的进一步表征有望对我们的 了解调节细胞生长的基本细胞信号机制。vt.给出 新型相扑E1抑制剂的发现，我们提出的研究将有助于加速 开发针对泛素样修饰的治疗应用。 好了！

ABSTRACT Ras proteins are GTPases that activate multiple signaling cascades, which modulate cell survival, proliferation, migration, and differentiation. Ras proteins are regulated by almost all known post-translational modifications, including farnesylation, palmitoylation, phosphorylation, ubiquitination, and acetylation. However, it remains unknown whether Ras proteins are modified by sumoylation. We recently discovered that all three forms of Ras protein are SUMO3-modified. Our further studies reveal that lysine 42 (K42) is the primary residue for sumoylation, whereas PIASγ and MEKK1 are candidate E3 ligases that sumoylate Ras. Sumoylation is essential for activating K-Ras and its downstream signaling. Furthermore, we have discovered a series of SUMO E1 inhibitors that target SUMO conjugation both in vitro and in vivo. The lead compounds 27A and SB-264 potently inhibit sumoylation, but not ubiquitination or neddylation. Significantly, these compounds display excellent bioactivities toward killing transformed pancreatic cells with K-Ras mutations at glycine 12 or glycine 13 and suppress their migration. Given the role of sumoylation in controlling functions of key cellular regulators and the paramount importance of K- Ras in cell proliferation and transformation, we hypothesize that sumoylation promotes K-Ras activity and that the SUMO regulatory pathway is an excellent target for development of anti- cancer drugs. Three Specific Aims are proposed to test the validity of the hypothesis. We will determine the mechanism by which sumoylation regulates K-Ras activation, elucidate the regulatory network that controls K-Ras sumoylation, and investigate the efficacy of SUMO E1 inhibitors in suppressing proliferation of pancreatic cancer growth in preclinical mouse models. Further characterization of K-Ras sumoylation promises to have a profound impact on our understanding of the fundamental cellular signaling mechanisms that regulate cell growth. Given the discovery of novel SUMO E1 inhibitors, our proposed studies will help to accelerate the development of therapeutic applications that target ubiquitin-like modifications. !