Elucidating novel molecular mechanisms of irisin-mediated effects via integrin

项目概要： 锻炼在很多方面对身体有益。骨骼肌、脑、肝、骨、脂肪组织的功能 和心脏都能从各种体育活动和训练中获益。残疾人，病态的 肥胖症或与年龄有关的疾病，通常是身体不活跃，这加剧了他们的症状，并导致 发展其他类型的疾病，如2型糖尿病，心血管疾病，和一些 癌症的形式。对运动的科学探索已经变得更加分子化， 以及介导这些益处的分子。Irisin已被鉴定为运动诱导的激素， 在各种组织/器官中体现了对运动的许多适应，包括皮下组织的“布朗宁”， 脂肪组织、骨重塑、改善认知缺陷和神经病理学，并促进肌生成 骨骼肌。 在骨和脂肪中，鸢尾素的作用通过αv整联蛋白介导，αvβ5被鉴定为主要受体。 然而，我对鸢尾素和αvβ5之间直接相互作用的生物化学和生物物理学表征， 表明极弱的结合，而诱导可检测量的 在体内和培养的细胞中，鸢尾素介导的作用非常低，表明鸢尾素/受体非常高 结合亲和力这一悖论可以解释为存在一个额外的因素， 鸢尾素/整联蛋白相互作用和鸢尾素介导的整联蛋白活化。我的初步数据显示， 运动诱导的循环蛋白Hsp 90 α与整合素αvβ5结合，并作为辅助因子介导运动诱导的细胞凋亡。 鸢尾素与整联蛋白的结合和鸢尾素诱导的整联蛋白信号传导。鸢尾素与许多整合素配体不同， 鸢尾素很小，高度糖基化，缺乏公认的整合素结合基序，表明 配体与整联蛋白结合的非规范方式。 生物物理和生物化学方法将用于表征由鸢尾素（WT和WT）形成的复合物。 糖基化突变体）、αvβ5和Hsp 90 α。该分子模型将首先在HEK 293 T细胞中进行测试 异位表达αv和β5，肌肉和脂肪细胞，使用分子方法和荧光 显微镜将在小鼠中进一步评价Hsp 90 α的作用。综合起来，这些研究将 我们对鸢尾素介导的（或一般来说，鸢尾素介导的）整合素信号传导的理解，这将有助于药物治疗。 和抗体开发，以治疗肥胖症，老年相关疾病和神经或肌肉疾病患者， 退行性疾病 拟议的项目代表了生物化学/生物物理学以及细胞生物学之间的巨大平衡， 我在读博士时学过细胞代谢和动物生理学， Spiegelman实验室使用的技术。由布鲁斯的网络，DFCI和HMS提供的资源， 极大地促进了我的研究，并将支持我成为一名独立的科学家。

PROJECT SUMMARY: Exercise benefits the body in many ways. The functions of skeletal muscle, brain, liver, bone, adipose tissue and heart all gain from various types of physical activity and training. People suffering from disabilities, morbid obesity, or age-related diseases, are usually physically inactive, which exacerbates their symptoms and leads to development of other types of diseases, such as type 2 diabetes mellitus, cardiovascular diseases, and some forms of cancers. Scientific explorations of exercise have become more molecular, focusing on the pathways and molecules that mediate these benefits. Irisin has been identified as an exercise-induced hormone that embodies many adaptations to exercise in a variety of tissues/organs, including “browning” of subcutaneous adipose tissue, bone remodeling, improving cognitive deficits and neuropathology, and promoting myogenesis of skeletal muscles. In bone and fat, the effects of irisin are mediated via αv integrins, with αvβ5 identified as the major receptor. However, my biochemical and biophysical characterization of direct interaction between irisin and αvβ5 suggested extremely weak binding, while the concentrations of irisin that induce detectable amount of irisin-mediated effects in the body and in the cultured cells are really low, indicating a very high irisin/receptor binding affinity. This paradox could be explained by the existence of an additional factor that facilitates irisin/integrin interaction and irisin-mediated integrin activation. My preliminary data suggested that an exercise-induced circulating protein Hsp90α binds to integrin αvβ5, and functions as a cofactor to mediate the binding of irisin to integrin and irisin-induced integrin signaling. Irisin is different from many integrin ligands in that irisin is small, heavily glycosylated, and lacks the well-identified integrin binding motif, indicating a non-canonical ways of ligand binding to integrins. Biophysical and biochemical approaches will be used to characterize the complexes formed by irisin (WT and glycosylation mutants), αvβ5 and Hsp90α. The molecular model will be firstly tested in HEK293T cells ectopically expressing αv and β5, and muscle and fat cells, using molecular approaches and fluorescence microscopy. The effects of Hsp90α will be further evaluated in mice. Taken together, these studies will advance our understanding of irisin-mediated (or hormone-mediated, in general) integrin signaling, which will assist drug and antibody development to treat patients with obesity, aged-related diseases and neuro- or muscular degenerative disorders. The proposed project represents a great balance between biochemistry/biophysics as well as cell biology, in which I was trained during my Ph.D, and cell metabolism and animal physiology, which are the primary technologies employed by the Spiegelman lab. The resources provided by Bruce’s networks, DFCI and HMS, tremendously facilitated my research, and will support me to become an independent scientist.