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Arch Biochem Biophys. 2000 Jul 15;379(2):337-43.

Caspase-mediated proteolytic activation of calcineurin in thapsigargin-mediated apoptosis in SH-SY5Y neuroblastoma cells.

Author information

1
Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.

Abstract

We previously demonstrated a loss in calmodulin (CaM)-dependent protein kinase activity in SH-SY5Y cells undergoing thapsigargin-mediated apoptosis, (K. M. McGinnis et al., 1998, J. Biol. Chem. 273, 19993-20000). Here we demonstrate that the large subunit of the CaM-dependent protein phosphatase 2B (calcineurin) is fragmented during SH-SY5Y cell apoptosis to a major fragment of 45 kDa in a caspase inhibitor-sensitive manner. A 45-kDa fragment was also produced when purified calcineurin was digested with recombinant caspase-3. The major cleavage site was identified to be DFGD* G(386)ATAA, which removes the C-terminal CaM-binding and autoinhibitory regions from the catalytic domain. Phosphatase activity increased progressively with caspase-3 digestion, coupled with the eventual loss of CaM-dependency. Calcineurin-mediated dephosphorylation of NFATc was also detected in thapsigargin-treated cells. Last, calcineurin inhibitors FK506 and cypermethrin provided partial protection against thapsigargin-mediated apoptosis, suggesting that calcineurin overactivation contributes to thapsigargin-induced apoptosis.

PMID:
10898953
DOI:
10.1006/abbi.2000.1889
[Indexed for MEDLINE]

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