Critical role of calpain-mediated cleavage of calcineurin in excitotoxic neurodegeneration.
Calcineurin and calpain, a Ca2+/calmodulin-dependent protein phosphatase and a Ca2+-dependent cysteine protease, respectively, mediate neuronal cell death through independent cascades. Here, we report that during neuroexcitotoxicity, calcineurin A (CnA) is directly cleaved by calpain in vitro and in vivo, resulting in the enzyme being converted to an active form. Mass spectrometry identified three cleavage sites in CnA, two of which were constitutively active forms. Overexpression of the cleaved CnA induced caspase activity and neuronal cell death. Calpain inhibitors and membrane-permeable calpastatin peptides not only blocked the cleavage of CnA, but also protected against excitotoxic neuronal cell death in vitro and in vivo. These results indicate that CnA is a crucial target for calpain, and the calpain-mediated activation of CnA triggers excitotoxic neurodegeneration. This study established a molecular link between calpain and calcineurin, thereby demonstrating a new mechanism for proteolytical regulation of calcineurin by calpain in response to certain pathological states.
Wu
Hai-Yan
HY
Department of Physiology, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata, Okayama, 700-8558 Japan.
Tomizawa
Kazuhito
K
Oda
Yoshiya
Y
Wei
Fan-Yan
FY
Lu
Yun-Fei
YF
Matsushita
Masayuki
M
Li
Sheng-Tian
ST
Moriwaki
Akiyoshi
A
Matsui
Hideki
H
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019703:Calcineurin / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002154:Calpain / Q000502:physiology*; D002478:Cells, Cultured; D018698:Glutamic Acid / Q000633:toxicity; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D007608:Kainic Acid / Q000633:toxicity; D008297:Male; D051379:Mice; D008959:Models, Neurological; D008969:Molecular Sequence Data; D009410:Nerve Degeneration / Q000139:chemically induced / Q000503:physiopathology*; D051381:Rats; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D018698:Glutamic Acid; D019703:Calcineurin; D002154:Calpain; D007608:Kainic Acid