Regulation of EGF receptor trafficking fate by phosphorylation and Odin

生长因子与受体的结合是调节后生动物生长发育的关键机制。表皮生长因子受体是一种典型的生长因子受体。激活的EGFR通过内吞作用迅速内化。内化的EGFR要么循环回到细胞表面，要么在溶酶体中降解，这是运输分类开关的结果。EGFR也内化和循环响应细胞应激。这些过程控制着细胞表面的受体密度，并反过来对不同的配体浓度梯度和环境线索发出信号反应，这在后生动物中是高度可变的。我们的长期目标是在定量机制方面了解动态共价修饰和蛋白质相互作用如何控制生长因子受体的运输命运。

Binding of growth factors to receptors is a key mechanism that regulates the growth and development of metazoans. Epidermal growth factor receptor (EGFR) is a prototypical growth factor receptor. Activated EGFR is rapidly internalization by endocytosis. Internalized EGFR either recycle back to the cell surface or degrade in lysosomes as a consequence of a trafficking sorting switch. EGFR also internalize and recycle in response to cellular stresses. These processes control receptor density at the cell surface, and in turn signaling responses to diverse ligand concentration gradients and environmental cues, which are highly variable in metazoans.Our long term objective is to understand in quantitative mechanistic terms, how dynamic covalent modifications and protein interactions control the trafficking fate of growth factor receptors. We discovered EGFR phosphorylations (Y998, S1039) and the protein Odin as factors affecting EGFR trafficking. For example, failure to phosphorylate activated EGFR at Y998 causes recycling, whereas cells without Odin lack EGFR recycling. Regulation of receptor trafficking has been intensively studied, but molecular mechanistic details of how EGFR phosphorylation regulates its recycle-or-degrade trafficking fate are not known. Our near term objective is to determine the molecular mechanism of phosphorylation-mediated EGFR sorting that constitutes a recycle-or-degrade switch. To achieve this, we propose the following specific aims: Aim 1: Address questions that test Odin’s role in EGFR recycling: (A) Does Odin bind Y998 for recycling, but not pY998, which stimulates degradation? (B) Does Odin function in stress-induced EGFR recycling? (C) Does phosphorylation of Odin modulate its interaction with EGFR? Aim2: Test if EGFR-S1039 phosphorylation controls EGFR recycling, and prevents transport to the lysosome. (A) Is S1039 required for EGFR recycling? (B) Does a receptor-associated phosphatase modulate S1039 phosphorylation, and consequently EGFR recycling? (C) Determination of temporal and spatial regulation of EGFR-S1039 phosphorylation towards defining its role in recycling. A mechanistic understanding phosphorylation/Odin-mediated EGFR sorting will lead to future studies of how receptor trafficking modulates growth factor and environmental signals in complex organisms. This program will also contribute to the training of HQP in the fields of molecular and cell biology, and proteomics.