Negative regulation of neurotransmitter release by calpain: a possible involvement of specific SNAP-25 cleavage.
Synaptic transmission is conducted by neurotransmitters released from presynaptic nerve terminals by means of Ca2+-dependent exocytosis of synaptic vesicles. Formation of a complex of soluble N-ethylmaleimide-sensitive fusion protein receptor (SNARE) proteins, including vesicle-associated membrane protein-2 (VAMP-2) in the synaptic vesicle membrane, and syntaxin 1 and synaptosomal-associated protein of 25 kDa (SNAP-25) in the plasma membrane, is essential for exocytosis. Ionomycin treatment of cultured rat cerebellar granule cells led to cleavage of SNAP-25, but not syntaxin 1 and VAMP-2, that was dependent on extracellular Ca2+. Cleavage was also induced by N-methyl-D-aspartate (NMDA) treatment, but not by depolarization. The use of various site-specific antibodies to SNAP-25, suggested that the cleavage site was in the N-terminal domain of SNAP-25. Calpain inhibitors abolished the Ca2+-dependent cleavage of SNAP-25 and markedly facilitated Ca2+-dependent glutamate (Glu) release from cerebellar granule cells. These results suggest that calpain may play an important role in the long-lasting regulation of synaptic transmission by suppressing neurotransmitter release, possibly through the proteolytic cleavage of SNAP-25.
School of Life Sciences, Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo, Japan.
Kosuke
K
Ando
Yoshihisa
Y
Kudo
Masami
M
Takahashi
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies / Q000494:pharmacology; D015153:Blotting, Western / Q000379:methods; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002154:Calpain / Q000494:pharmacology*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004151:Dipeptides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects*; D004347:Drug Interactions; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D006023:Glycoproteins / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D016202:N-Methylaspartate / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000276:immunology / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D050825:Synaptosomal-Associated Protein 25; D013997:Time Factors
D000906:Antibodies; D004151:Dipeptides; D018690:Excitatory Amino Acid Agonists; D006023:Glycoproteins; D007476:Ionophores; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; C039304:calpain inhibitors; C071482:calpeptin; D018698:Glutamic Acid; D015759:Ionomycin; D016202:N-Methylaspartate; D002154:Calpain; D011188:Potassium; D002118:Calcium