Myosin Va is proteolysed in rat cerebellar granule neurons after excitotoxic injury

• Published in: Neuroscience letters 2004-09, Vol.367 (3), p.404-409
• Main Authors: Alavez, Silvestre, Morán, Julio, Franco-Cea, Ari, Ortega-Gómez, Alette, Casaletti, Luciana, Cameron, Luiz Claudio
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animals; Animals, Newborn; Biological and medical sciences; Blotting, Western - methods; Calpain; Cell Death - drug effects; Cells, Cultured; Cerebellum - cytology; Cysteine Proteinase Inhibitors - pharmacology; Drug Interactions; Excitatory Amino Acids - toxicity; Fundamental and applied biological sciences. Psychology; Glutamate; Glycoproteins - pharmacology; Leupeptin; Leupeptins - pharmacology; Myosin Heavy Chains - metabolism; Myosin Type V - metabolism; Myosin Va; Neurodegeneration; Neurons - drug effects; Neurons - metabolism; Proteolysis; Rats; Tetrazolium Salts; Thiazoles; Time Factors; Vertebrates: nervous system and sense organs
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2004.06.043

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 Ca 2+-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 μM), kainate (100 μM) or NMDA (150 μM) during 3–24 h, the proteolytic processing of myosin Va is markedly increased. This proteolysis is inhibited by leupeptin (100 μM) and calpain inhibitor I (50 μM). 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.