title: Myosin Va is proteolysed in rat cerebellar granule neurons after excitotoxic injury.
abstract: Cerebellar granule neurons when exposed to glutamate die through an excitotoxic mechanism induced by overactivation of glutamate receptors. This kind of cell death is mediated by an overload of intracellular calcium involving calpain activation, a Ca2+ -dependent intracellular cysteine protease, among other intracellular responses. On the other hand, class V myosins are proteins that move cargo along actin filaments and one of its members, myosin Va, is involved in vesicles transport. Here we studied the effect of excitotoxicity on myosin Va in cultured cerebellar granule neurons. Western blot analysis of control cultures shows a band corresponding to myosin Va as well as an 80 kDa band corresponding to its proteolytic product by calpain. When cells are exposed to glutamate (500 microM), kainate (100 microM) or NMDA (150 microM) during 3-24 h, the proteolytic processing of myosin Va is markedly increased. This proteolysis is inhibited by leupeptin (100 microM) and calpain inhibitor I (50 microM). These inhibitors also significantly improve the morphological appearance of the neurons possibly through the preservation of the cytoskeleton integrity. Our results suggest that myosin Va is a target for calpain I during an excitotoxic injury and could lead to a new area of research to address the participation of molecular motors in neurotoxicity.
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Neurociencias, Apartado Postal 70-253, 04510, DF, Mexico. salavez@ifc.unam.mx
authors.forename: Silvestre
authors.initials: S
authors.lastname: Alavez
authors.forename: Julio
authors.initials: J
authors.lastname: Morán
authors.forename: Ari
authors.initials: A
authors.lastname: Franco-Cea
authors.forename: Alette
authors.initials: A
authors.lastname: Ortega-Gómez
authors.forename: Luciana
authors.initials: L
authors.lastname: Casaletti
authors.forename: Luiz Claudio
authors.initials: LC
authors.lastname: Cameron
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western / Q000379:methods; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004347:Drug Interactions; D018846:Excitatory Amino Acids / Q000633:toxicity*; D006023:Glycoproteins / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D018995:Myosin Heavy Chains / Q000378:metabolism*; D024701:Myosin Type V / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors
chemical_list: D015853:Cysteine Proteinase Inhibitors; D018846:Excitatory Amino Acids; D006023:Glycoproteins; D007976:Leupeptins; C513081:Myo5a protein, rat; D013778:Tetrazolium Salts; D013844:Thiazoles; C039304:calpain inhibitors; D024701:Myosin Type V; D018995:Myosin Heavy Chains; C022616:thiazolyl blue; C032854:leupeptin