Calpain activity contributes to the control of SNAP-25 levels in neurons.
Calpains are a family of calcium-dependent proteases with abundant expression in the CNS, and potent in cleaving some synaptic components. Assessment of calpain activity by its fluorescent substrate, Boc-Leu-Met-CMAC, revealed that cultured neurons display a significant level of constitutive enzyme activity. Notably, calpain activity differs in distinct neuronal populations, with a significantly higher level of activity in GABAergic cells. Using selectively-enriched cultures of fast-spiking GABAergic interneurons, we show that calpain activity partially contributes to the post-translational down regulation of SNAP-25, a calpain substrate, in differentiated GABA cells. In addition, we demonstrate that SNAP-25 is cleaved by calpain in response to acute seizures induced by intraperitoneal kainate injection in vivo. These data indicate that calpains in neurons are active even at physiological calcium concentrations and that different levels of calpain activation in selected neuron subtypes may contribute to the pattern of synaptic protein expression.
Grumelli
Carlotta
C
Dipartimento di Farmacologia Medica, Istituto CNR di Neuroscienze, Universita' di Milano, Italy.
Berghuis
Paul
P
Pozzi
Davide
D
Caleo
Matteo
M
Antonucci
Flavia
F
Bonanno
Giambattista
G
Carmignoto
Giorgio
G
Dobszay
Marton Benedek
MB
Harkany
Tibor
T
Matteoli
Michela
M
Verderio
Claudia
C
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D002478:Cells, Cultured; D003374:Coumarins / Q000737:chemistry / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism; D004622:Embryo, Mammalian / Q000033:anatomy & histology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007608:Kainic Acid / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D012640:Seizures / Q000139:chemically induced / Q000378:metabolism; D050825:Synaptosomal-Associated Protein 25 / Q000235:genetics / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D019208:Brain-Derived Neurotrophic Factor; D003374:Coumarins; D004151:Dipeptides; D018690:Excitatory Amino Acid Agonists; D020033:Protein Isoforms; D050825:Synaptosomal-Associated Protein 25; C071482:calpeptin; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D002154:Calpain; D007608:Kainic Acid; D002118:Calcium