title: Generation of constitutively active calcineurin by calpain contributes to delayed neuronal death following mouse brain ischemia.
abstract: Calpain, a Ca(2+)-dependent cysteine protease, in vitro converts calcineurin (CaN) to constitutively active forms of 45 kDa and 48 kDa by cleaving the autoinhibitory domain of the 60 kDa subunit. In a mouse middle cerebral artery occlusion (MCAO) model, calpain converted the CaN A subunit to the constitutively active form with 48 kDa in vivo. We also confirmed increased Ca(2+)/CaM-independent CaN activity in brain extracts. The generation of constitutively active and Ca(2+)/CaM-independent activity of CaN peaked 2 h after reperfusion in brain extracts. Increased constitutively active CaN activity was associated with dephosphorylation of dopamine-regulated phosphoprotein-32 in the brain. Generation of constitutively active CaN was accompanied by translocation of nuclear factor of activated T-cells (NFAT) into nuclei of hippocampal CA1 pyramidal neurons. In addition, a novel calmodulin antagonist, DY-9760e, blocked the generation of constitutively active CaN by calpain, thereby inhibiting NFAT nuclear translocation. Together with previous studies indicating that NFAT plays a critical role in apoptosis, we propose that calpain-induced CaN activation in part mediates delayed neuronal death in brain ischemia.
authors.affiliation: Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
authors.forename: Norifumi
authors.initials: N
authors.lastname: Shioda
authors.forename: Shigeki
authors.initials: S
authors.lastname: Moriguchi
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Shirasaki
authors.forename: Kohji
authors.initials: K
authors.lastname: Fukunaga
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism / Q000473:pathology*; D019703:Calcineurin / Q000378:metabolism*; D002154:Calpain / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism; D002364:Caseins / Q000493:pharmacokinetics; D016923:Cell Death / Q000187:drug effects; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D007150:Immunohistochemistry / Q000379:methods; D047468:Immunoprecipitation / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008840:Microfilament Proteins / Q000378:metabolism; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects*; D010759:Phosphorus Isotopes / Q000493:pharmacokinetics; D021122:Protein Subunits / Q000378:metabolism; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013049:Spectrin
chemical_list: D019703:Calcineurin; D002154:Calpain; D002352:Carrier Proteins; D002364:Caseins; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D010759:Phosphorus Isotopes; D021122:Protein Subunits; D013049:Spectrin