Regulation of Mutationally Activated Gq/11

摘要 异源三聚体G蛋白（heterotrimeric G proteins，G蛋白）是一类重要的G蛋白偶联受体 GPCR对多种细胞内反应起重要作用，从而在广泛的细胞内信号传导中发挥重要作用。 各种细胞外信号调节无数的生理过程。但也 越来越多的人认识到G蛋白可以独立于GPCR发挥作用。突出 非GPCR依赖性G蛋白功能的生理相关性，组成性激活体细胞突变 在几种G β亚基中，已经鉴定出并显示出与人类疾病有关，最突出的是 癌该研究项目的重点是高度相似的p53 q和p53 11的组成型活性突变体 亚单位，统称为CQq/11。在两个热点残基之一的突变，导致抑制 GTP水解关闭机制可以将q/11转化为葡萄膜黑色素瘤的致癌驱动因子，并且 这种组成型激活的GSTQ/11突变也与血管肿瘤、毛细血管肿瘤、血管瘤、血管 畸形、先天性血管瘤和Sturge Weber综合征。该研究项目将重点关注 揭示了通过突变激活的GSTQ/11调节信号传导的基本细胞机制。G β亚基是 通常被认为是异常困难的蛋白质， 抑制剂的然而，最近的许多研究表明，高度相似的天然产物 YM-254890和FR 900359是野生型和突变激活的Gdq/11的有效抑制剂。我们的工作 已经发现了这些抑制剂的一种意想不到的作用机制，导致YM- 254890和FR 900359至少部分地通过调节β-内酰胺q/11的亚细胞定位来抑制β-内酰胺q/11。 了解突变激活的BCLq/11的抑制和细胞调节的新机制可能 提出了用于破坏失调信号传导的新的治疗靶点或方法。在此目标 研究项目将通过各种实验方法进行，包括使用培养细胞， 免疫荧光显微术，活细胞的荧光显微术，组成性靶向特异性 亚细胞定位、生物传感器、药理学抑制剂、突变分析和生化测定。

Abstract Heterotrimeric G proteins () are well known for their function in linking G protein-coupled receptors (GPCRs) to a variety of intracellular responses, and thereby playing essential roles in transmitting a wide variety of extracellular signals into regulation of countless physiological processes. However, it has also become increasingly recognized that G proteins can function independently of GPCRs. Highlighting the physiological relevance of GPCR-independent G protein function, constitutively activating somatic mutations in several G subunits have been identified and shown to contribute to human disease, most prominently in cancer. This research project focuses on constitutively active mutants of the highly similar q and 11 subunits, collectively termed q/11. Mutations at one of two hotspot residues, that result in inhibition of the GTP hydrolysis turn-off mechanism, can convert q/11 into an oncogenic driver of uveal melanoma, and such constitutively activating q/11 mutations have also been associated with vascular tumors, capillary malformation, congenital hemangioma and Sturge Weber syndrome. This research project will focus on uncovering basic cellular mechanisms regulating signaling by mutationally activated q/11. G subunits are typically thought as exceptionally difficult proteins for which to develop pharmacological or molecular inhibitors. However, numerous recent studies have demonstrated that the highly similar natural products YM-254890 and FR900359 are effective inhibitors of wild type and mutationally activated q/11. Our work has uncovered an unexpected mechanism of action of these inhibitors leading to the hypothesis that YM- 254890 and FR900359 inhibit q/11, at least in part, by regulating subcellular localization of q/11. Understanding the novel mechanisms of inhibition and cellular regulation of mutationally activated q/11 may suggest novel therapeutic targets or approaches for disrupting dysregulated signaling. The objectives in this research project will be pursued by a variety of experimental approaches, including using cultured cells, immunofluorescence microscopy, fluorescence microscopy of live cells, constitutive targeting to specific subcellular locations, biosensors, pharmacological inhibitors, mutational analysis, and biochemical assays.