RP10: Role of Parkin in regulating GDNF signal transduction and receptor turnover in neurons

泛素蛋白连接酶Parkin的突变可通过改变蛋白质周转而导致帕金森S病(PD)。Parkin多聚泛素化一些底物以标记它们被蛋白酶体降解，而另一些底物，如Eps15，是单泛素化的。单质素化的Eps15不能与细胞表面受体结合并触发非细胞内吞，从而增强受体信号。我的实验室工作表明，Parkin和Eps15还调节神经胶质细胞系衍生神经营养因子(GDNF)受体Ret在神经元中的蛋白质周转。我们发现Ret可以与Eps15和parkin结合；parkin改变GDNF的内化；在parkin缺乏的小鼠中，Ret蛋白的数量似乎减少了。在这个项目中，我们将通过生化和细胞培养实验来研究parkin、Eps15和Ret是如何相互作用的；这种相互作用是如何调节的；以及parkin是如何影响神经元中Ret的内化、降解和信号传递的。此外，我们将研究这种相互作用在双转基因parkin和Ret小鼠中的生理学相关性，并通过分析具有parkin突变的帕金森病患者的脑组织。这些数据将使我们能够将Ret整合到PD患者改变的蛋白质网络中，并将增强我们对这种复杂疾病的理解。

Mutations in the ubiquitin protein ligase parkin can cause Parkinson s disease (PD) by altering protein turnover. Parkin polyublquitylates some substrates to mark them for degradation by the proteasome and others, such as Eps15, are monoubiquitylated. Monoubiquitylated Eps15 can not bind to cell surface receptors and trigger clathrindependent endocyotsis, thereby enhancing receptor signaling.Work from my laboratory suggests that parkin and Eps15 also regulate the protein turnover of the glial cell line-derived neurotrophic factor (GDNF) receptor Ret in neurons. We found that Ret can bind to Eps15 and parkin; parkin alters the internalization of GDNF; and the amount of Ret protein seems to be reduced in parkin-deficient mice.In this project, we will investigate how parkin, Eps15 and Ret interact; how this interaction is regulated; and how parkin influences the internalization, degradation and signaling of Ret in neurons by performing biochemical and cell culture experiments. In addition, we will study the physiological relevance of this interaction in double transgenic parkin and Ret mice and by analyzing brain tissue from PD patients with mutations in parkin. These data will allow Integrating Ret in the protein network altered in PD patients and will enhance our understanding of this complex disease.