Journal Article

Caspases Cleave the Amino-Terminal Calpain Inhibitory Unit of Calpastatin during Apoptosis in Human Jurkat T Cells

Masahiko Kato, Takashi Nonaka, Masatoshi Maki, Hidehiko Kikuchi and Shinobu Imajoh-Ohmi

in The Journal of Biochemistry

Published on behalf of The Japanese Biochemical Society

Volume 127, issue 2, pages 297-305
Published in print February 2000 | ISSN: 0021-924X
Published online February 2000 | e-ISSN: 1756-2651 | DOI: https://dx.doi.org/10.1093/oxfordjournals.jbchem.a022607
Caspases Cleave the Amino-Terminal Calpain Inhibitory Unit of Calpastatin during Apoptosis in Human Jurkat T Cells

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We have previously reported the activation of procalpain μ (precursor for low-calcium-requiring calpain) in apoptotic cells using a cleavage-site-directed antibody specific to active calpain [Kikuchi, H. and Imajoh-Ohmi, S. (1995) Cell Death Differ. 2, 195-199]. In this study, calpastatin, the endogenous inhibitor protein for calpain, was cleaved to a 90-kDa polypeptide during apoptosis in human Jurkat T cells. The limited proteolysis of calpastatin preceded the autolytic activation of procalpain. Inhibitors for caspases rescued the cells from apoptosis and simultaneously inhibited the cleavage of calpastatin. The full-length recombinant calpastatin was also cleaved by caspase-3 or caspase-7 at Asp-233 into the same size fragment. Cys-241 was also targeted by these caspases in vitro but not in apoptotic cells. Caspase-digested calpastatin lost its amino-terminal inhibitory unit, and inhibited three moles of calpain per mole. Our findings suggest that caspases trigger the decontrol of calpain activity suppression by degrading calpastatin.

Keywords: apoptosis; calpain; calpastatin; caspase; Jurkat T-celL

Journal Article.  0 words. 

Subjects: Biochemistry

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