Progress of endocytic CHRN to autophagic degradation is regulated by RAB5-GTPase and T145 phosphorylation of SH3GLB1 at mouse neuromuscular junctions in vivo
Progress of endocytic CHRN to autophagic degradation is regulated by RAB5-GTPase and T145 phosphorylation of SH3GLB1 at mouse neuromuscular junctions in vivo
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DOI：
10.1080/15548627.2016.1234564
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发表时间：
2016-10
期刊：
影响因子：
13.3
通讯作者：
Franziska Wild;M. Khan;Tatjana Straka;R. Rudolf
中科院分区：
文献类型：
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作者：
Franziska Wild;M. Khan;Tatjana Straka;R. Rudolf
内吞烟碱乙酰胆碱受体（CHRN）在萎缩性疾病中通过自噬/巨自噬降解，并伴随有自噬调节蛋白SH 3GLB 1。本研究探讨了SH 3GLB 1对CHRN贩运及其实施的功能作用。我们发现在CHRN囊泡数量增加的条件下，总SH 3GLB 1与苏氨酸-145磷酸化SH 3GLB 1的比率（SH 3GLB 1：p-SH 3GLB 1）增加。发现SH 3GLB 1的T145磷酸模拟物（T145 E）和磷酸缺陷（T145 A）突变体的过表达分别减缓或增强内吞CHRN囊泡的加工。早期内体协调器RAB 5的共表达在很大程度上挽救了由T145 E诱导的内吞CHRN囊泡的缓慢加工。SH 3GLB 1磷酸突变体不调节RAB 5与CHRN囊泡的表达或共定位，而是改变RAB 5活性调节剂的表达。总之，这些发现表明，SH 3GLB 1控制CHRN内吞运输的磷酸化和RAB 5依赖性的方式在步骤上游的自噬体形成。
ABSTRACT Endocytosed nicotinic acetylcholine receptors (CHRN) are degraded via macroautophagy/autophagy during atrophic conditions and are accompanied by the autophagic regulator protein SH3GLB1. The present study addressed the functional role of SH3GLB1 on CHRN trafficking and its implementation. We found an augmented ratio of total SH3GLB1 to threonine-145 phosphorylated SH3GLB1 (SH3GLB1:p-SH3GLB1) under conditions of increased CHRN vesicle numbers. Overexpression of T145 phosphomimetic (T145E) and phosphodeficient (T145A) mutants of SH3GLB1, was found to either slow down or augment the processing of endocytic CHRN vesicles, respectively. Co-expression of the early endosomal orchestrator RAB5 largely rescued the slow processing of endocytic CHRN vesicles induced by T145E. SH3GLB1 phosphomutants did not modulate the expression or colocalization of RAB5 with CHRN vesicles, but instead altered the expression of RAB5 activity regulators. In summary, these findings suggest that SH3GLB1 controls CHRN endocytic trafficking in a phosphorylation- and RAB5-dependent manner at steps upstream of autophagosome formation.