ARVCF调节cadherin/catenin复合体介导的细胞间黏附的分子机制研究

E-cad is a transmembrane protein, whose intracellular region forms E-cad/catenin complex. P120ctn is an Arm repeat protein which binds to the JMDcore of E-cad, and stabilizes E-cad/catenin complex. Uncoupling of p120ctn and JMDcore will lead to the internalization of E-cad. This is mainly related with the internalized motif beside the JMDcore,and C-terminus of p120ctn blocked the internalization motif. ARVCF is a member of p120ctn subfamily, and competes with p120ctn for binding to E-cadherin, resulting in the internalization of E-cad. The phosphorylation of ARVCF can reduce internalization of E-cad. We speculate that ARVCF binds to JMDcore by 1-5Arm,but the C-terminus of ARVCF cannot block the internalized motif. The change of phosphorylation of ARVCF, may open or close the internalization motif. We plan to detect three-dimensional structure of ARVCF/E-cad complex by NMR and X-ray, and construct mutation and spliceosome of ARVCF and E-cad, which reveal the molecular mechanism of ARVCF regulating E-cad from the point of view of molecular space structure.

E-cad是一种跨膜蛋白，胞内区可形成E-cad/catenin复合体。p120ctn是Arm重复蛋白，可结合E-cad的JMDcore区，稳定E-cad/catenin复合体。解联p120ctn与JMDcore，将导致E-cad的内化。这主要与JMDcore旁的内化位点有关，p120ctn的C-端阻断了内化位点。ARVCF是p120ctn亚家族成员之一，可以与p120ctn竞争结合E-cad，导致E-cad内化。ARVCF的磷酸化可减弱E-cad内化。我们推测：ARVCF依靠1-5Arm与 JMDcore结合，但其C-端却不能封闭内化位点。而改变ARVCF的磷酸化，则可以开放或封闭E-cad的内化位点。我们计划利用NMR及X-ray检测ARVCF/E-cad复合体的三维结构，并构建ARVCF和E-cad的突变/剪接体，从分子空间结构角度，揭示ARVCF调控E-cad的分子机机制。

E-cadherin（E-cad）是维持上皮细胞间黏附的跨膜蛋白，相邻细胞间的两个E-cad胞外区域形成反式二聚体。而E-cad的胞内区则形成cadherin/catenin复合体，并锚定于actin骨架。p120 catenin（p120ctn）的中央区为高度保守的Arm重复序列，两侧为N-末端调节区（NTR）和C-末端尾部区域（CTR）。p120ctn可以结合E-cad，并使其稳定在细胞膜上。这主要是通过p120ctn的1-5 ARM区与E-cad的juxtamembrane domain (JMD区)结合。.. 而p120ctn同家族成员ARVCF与p120ctn有相似结构。本研究发现ARVCF同样可以结合E-cad，但不能使E-cad稳定表达在细胞膜上。我们通过对ARVCF与E-cad的复合体晶体构造以及转染的构建剪接体实验结果进行检测分析，发现ARVCF的ARM-NTR区与E-cad的JMD core区在结合的过程中起到重要作用，这点与p120ctn/E-cad结合方式相似。同时ARVCF磷酸化可导致在细胞膜上表达的E-cad向胞浆转位（内化作用）减少，进而影响肺癌细胞的侵袭转移能力。