title: Progress of endocytic CHRN to autophagic degradation is regulated by RAB5-GTPase and T145 phosphorylation of SH3GLB1 at mouse neuromuscular junctions in vivo.
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.
authors.affiliation: a Interdisciplinary Center for Neurosciences, University of Heidelberg , Heidelberg , Germany.|b Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences , Mannheim , Germany.|c Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Wild
authors.affiliation: a Interdisciplinary Center for Neurosciences, University of Heidelberg , Heidelberg , Germany.|b Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences , Mannheim , Germany.|c Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany.
authors.forename: Muzamil Majid
authors.initials: MM
authors.lastname: Khan
authors.affiliation: a Interdisciplinary Center for Neurosciences, University of Heidelberg , Heidelberg , Germany.|b Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences , Mannheim , Germany.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Straka
authors.affiliation: a Interdisciplinary Center for Neurosciences, University of Heidelberg , Heidelberg , Germany.|b Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences , Mannheim , Germany.|c Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Rudolf
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D002738:Chloroquine / Q000494:pharmacology; D003714:Denervation; D004705:Endocytosis / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000187:drug effects / Q000294:innervation; D050505:Mutant Proteins / Q000378:metabolism; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010769:Phosphothreonine / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011978:Receptors, Nicotinic / Q000378:metabolism*; D012584:Sciatic Nerve / Q000187:drug effects / Q000473:pathology; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D050505:Mutant Proteins; D011978:Receptors, Nicotinic; C486100:Sh3glb1 protein, mouse; D010769:Phosphothreonine; D049452:Green Fluorescent Proteins; D002738:Chloroquine; D020696:rab5 GTP-Binding Proteins
keywords: AChR; Bif-1; NMJ; RAB5; SH3GLB1; acetylcholine receptor; endophilin B1; neuromuscular junction; skeletal muscle; synapse