GCK家族OSR1激酶信号转导的结构与功能研究

Germinal Center Kinases (GCKs) play a vital role in many aspects of cell functions by regulating cell polarity, migration, proliferation, differentiation, apoptosis and ion homoeostasis. Therefore GCKs are important mediators for many fundamental biological processes such as stress response, development, metabolism and immune regulation. As a GCK family member, OSR1 can phosphorylate and activate ion co-transporters to regulate cell osmotic stress, control cell volume and blood pressure. Thus OSR1 is a potential target to develop novel drugs for the efficient treatment of hypertension. Recent studies show that mammalian scaffolding protein MO25 can bind with OSR1 to dramatically promote its kinase activity, regulating the phosphorylation and activation of the downstream ion co-transporters. Here we propose to use protein engineering and structural analysis as primary tools, combining biochemistry and cell biology, to systemically explore the functional mechanisms of OSR1 signaling. We first determine the high-resolution structures of OSR1 and OSR1-MO25 complexes. Subsequent mutational studies will be carried out at the levels of biochemistry and cell biology to establish the mechanistic model for precise control of OSR1 kinase activaty. Furthermore, with the help of MO25, we intend to discover novel effectors related to OSR1 signaling especially its downstream substrates. The proposed work will not only improve our understanding of the molecular mechanism of OSR1 signaling in the regulation of ion homeostasis and blood pressure, but also provide a basis for further developing novel antihypertensive drugs.

GCK激酶广泛参与细胞应激反应、发育和代谢等若干重要生物学过程。该家族成员OSR1可通过磷酸化下游离子通道蛋白调节细胞渗透压，维持细胞体积和机体血压稳定。因此OSR1是一个潜在的治疗高血压等疾病的新型药物靶标。最新研究发现，哺乳动物MO25可与OSR1结合从而显著提高OSR1的激酶活性。本项目建议结合结构生物学、生物化学和细胞生物学等综合研究OSR1及其与MO25形成复合物对细胞功能的调控。我们将首先获取OSR1及其与MO25形成复合物的高分辨率结构。然后，在生化和细胞层面上进行突变研究，建立OSR1激酶活性的精确调控模型，深入阐释OSR1信号通路的调控机制。进一步，在MO25辅助下，寻找新的OSR1信号通路相关因子特别是下游底物，完善OSR1在调节细胞应对外界渗透压变化，维持细胞离子稳态和机体正常血压水平等方面的分子机制，同时为可能的新型降压药物开发提供一定的理论依据。

GCK激酶广泛参与细胞应激反应、发育和代谢等若干重要生物学过程。该家族成员OSR1可通过磷酸化下游离子通道蛋白调节细胞渗透压，维持细胞体积和机体血压稳定。因此OSR1是一个潜在的治疗高血压等疾病的新型药物靶标。最新研究发现，哺乳动物MO25可与OSR1结合从而显著提高OSR1的激酶活性。本项目结合结构生物学、生物化学和细胞生物学等综合研究OSR1及其与MO25形成复合物对细胞功能的调控。我们解析了与OSR1的N端高度同源的GCKIII家族激酶MST4的N端与支架蛋白MO25复合物的结构，以及MST4与脑海绵状血管瘤因子3（CCM3）的复合物结构，通过OSR1与MST4结构的分析，进一步研究MO25调控GCK激酶的相同或相异的分子机制；同时，通过对OSR1及其与MO25形成复合物的结构分析，我们对OSR1的激活机制进行了研究，阐释了OSR1的自抑制机制，提出了“双重锁”模型。然后，在生化和细胞层面上进行突变研究，建立OSR1激酶活性的精确调控模型，深入阐释OSR1信号通路的调控机制，完善OSR1在调节细胞应对外界渗透压变化，维持细胞离子稳态和机体正常血压水平等方面的分子机制，同时为可能的新型降压药物开发提供一定的理论依据。