Molecular Scaffolds Direct MAPK Signaling Specificity

描述（由申请人提供）：正常的细胞功能依赖于环境信号的能力，通过激活特定的细胞表面受体来引发不同的反应，然而这些信号通常集中在MAPK家族的相同成员上。当如此多不同的受体最终激活同一种酶时，细胞如何维持信号转导的特异性？我之前的工作帮助确定了内吞机制的组成部分（例如b-阻滞蛋白）可以组装脚手架复合物，从而指导亚细胞定位、持续时间和MAPK活性的结果。这些研究调查了这些内体支架可以指导不同细胞结果的机制，通过表征响应蛋白酶活化受体-2 （PAR-2）形成的分子支架，通过隔离和延长MAPK在前沿的活性来促进趋化性，并将其与响应促进MAPK核易位和增殖的受体形成的分子支架进行比较。我们提出了以下问题：1)PAR-2内体支架是否将MAPK隔离到亚细胞结构域，在那里它指导细胞骨架的局部重组？受体/b-阻滞蛋白相互作用和分子接触是否在每个内体支架内最终决定受体激活的结果？3)内体支架如何控制细胞特定区域的激酶活性？从细胞生物学的基本角度来看，了解内体支架决定信号特异性的机制是很重要的，因为最近的研究表明，这种机制被各种各样的受体所利用。此外，本研究关注的受体PAR-2参与了大量正常的生理和病理过程；我们实验室研究的两个领域是肿瘤转移和维持结肠上皮完整性。因此，了解PAR-2信号的分子基础可能最终导致治疗转移和炎症性肠病的新靶点。

DESCRIPTION (provided by applicant): Normal cellular function is dependent on the ability of environmental signals to elicit distinct responses through activation of specific cell surface receptors, and yet these signals often converge on the same members of the MAPK family. How can cells maintain specificity of signal transduction when so many different receptors ultimately activate the same enzyme? My previous work helped establish that components of the endocytotic machinery, (e.g. b-arrestin), can assemble scaffolding complexes that direct the subcellular localization, duration and outcome of MAPK activity. These studies investigate the mechanism by which these endosomal scaffolds can direct distinct cellular outcomes, by characterizing a molecular scaffold formed in response to protease-activated receptor-2 (PAR-2) that promotes chemotaxis by sequestering and prolonging MAPK activity at the leading edge and comparing it to one formed in response to a receptor that promotes nuclear translocation of MAPK and proliferation. We pose the following questions: 1) Does the PAR-2 endosomal scaffold sequester MAPK to a subcellular domain where it directs localized reorganization of the cytoskeleton? 2) Do receptor/b-arrestin interactions and molecular contacts within each endosomal scaffold and ultimately determine the outcome of receptor activation? 3) How does the endosomal scaffold control kinase activity in a specialized region of the cell? Understanding the mechanism by which endosomal scaffolds determine signaling specificity is important from a fundamental cell biological perspective as recent studies suggest this mechanism is utilized by a wide variety of receptors. Furthermore, the receptor on which this study focuses, PAR-2, is involved in a plethora of normal physiological and pathological processes; two areas studied in our laboratory are tumor metastasis and maintenance of colonic epithelial integrity. Therefore, understanding the molecular basis of PAR-2 signaling may ultimately lead to new targets for the treatment of metastasis and inflammatory bowel diseases.