title: Agrin regulates CLASP2-mediated capture of microtubules at the neuromuscular junction synaptic membrane.
abstract: Agrin is the major factor mediating the neuronal regulation of postsynaptic structures at the vertebrate neuromuscular junction, but the details of how it orchestrates this unique three-dimensional structure remain unknown. Here, we show that agrin induces the formation of the dense network of microtubules in the subsynaptic cytoplasm and that this, in turn, regulates acetylcholine receptor insertion into the postsynaptic membrane. Agrin acted in part by locally activating phosphatidylinositol 3-kinase and inactivating GSK3β, which led to the local capturing of dynamic microtubules at agrin-induced acetylcholine receptor (AChR) clusters, mediated to a large extent by the microtubule plus-end tracking proteins CLASP2 and CLIP-170. Indeed, in the absence of CLASP2, microtubule plus ends at the subsynaptic muscle membrane, the density of synaptic AChRs, the size of AChR clusters, and the numbers of subsynaptic muscle nuclei with their selective gene expression programs were all reduced. Thus, the cascade linking agrin to CLASP2-mediated microtubule capturing at the synaptic membrane is essential for the maintenance of a normal neuromuscular phenotype.
authors.affiliation: Department of Biomedicine, Institute of Physiology, University of Basel, CH-4056 Basel, Switzerland.
authors.forename: Nadine
authors.initials: N
authors.lastname: Schmidt
authors.forename: Sreya
authors.initials: S
authors.lastname: Basu
authors.forename: Stefan
authors.initials: S
authors.lastname: Sladecek
authors.forename: Sabrina
authors.initials: S
authors.lastname: Gatti
authors.forename: Jeffrey
authors.initials: J
authors.lastname: van Haren
authors.forename: Susan
authors.initials: S
authors.lastname: Treves
authors.forename: Jan
authors.initials: J
authors.lastname: Pielage
authors.forename: Niels
authors.initials: N
authors.lastname: Galjart
authors.forename: Hans Rudolf
authors.initials: HR
authors.lastname: Brenner
mesh_terms: D018171:Agrin / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D017353:Gene Deletion; D005786:Gene Expression Regulation; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D049452:Green Fluorescent Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000378:metabolism; D009469:Neuromuscular Junction / Q000378:metabolism*; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011950:Receptors, Cholinergic / Q000378:metabolism; D013570:Synaptic Membranes / Q000378:metabolism*
chemical_list: D018171:Agrin; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D049452:Green Fluorescent Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D019869:Phosphatidylinositol 3-Kinases; D011950:Receptors, Cholinergic; C506523:CLASP2 protein, mouse; C076744:cytoplasmic linker protein 170; C000605507:Gsk3b protein, mouse