In vivo calpain/caspase cross-talk during 3-nitropropionic acid-induced striatal degeneration: implication of a calpain-mediated cleavage of active caspase-3.
The role of caspases and calpains in neurodegeneration remains unclear. In this study, we focused on these proteases in a rat model of Huntington's disease using the mitochondrial toxin 3-nitropropionic acid (3NP). Results showed that 3NP-induced death of striatal neurons was preceded by cytochrome c redistribution, transient caspase-9 processing, and activation of calpain, whereas levels of the active/processed form of caspase-3 remained low and were even reduced as compared with control animals. We evidenced here that this decrease in active caspase-3 levels could be attributed to calpain activation. Several observations supported this conclusion. 1) Pharmacological blockade of calpain in 3NP-treated rats increased the levels of endogenous processed caspase-9 and caspase-3. 2) Cell-free extracts prepared from the striatum of 3NP-treated rats degraded in vitro the p34 and p20 subunits of active recombinant caspase-9 and caspase-3, respectively. 3) This degradation of p34 and p20 could be mimicked by purified mu-calpain and was prevented by calpain inhibitors. 4) mu-Calpain produced a loss of the DEVDase (Asp-Glu-Val-Asp) activity of active caspase-3. 5) Western blot analysis and experiments with 35S-radiolabeled caspase-3 showed that mu-calpain cleaved the p20 subunit of active caspase-3 near its catalytic site. 6) mu-Calpain activity was selectively inhibited (IC50 of 100 mum) by a 12 amino acid peptide corresponding to the C terminus of p20. Our results showed that calpain can down-regulate the caspase-9/caspase-3 cell death pathway during neurodegeneration due to chronic mitochondrial defects in vivo and that this effect may involve, at least in part, direct cleavage of the caspase-3 p20 subunit.
Bizat
Nicolas
N
Unité de Recherche Associée Commissariat à l'Energie Atomique (CEA)-CNRS 2210, Service Hospitalier Frédéric Joliot, Département de Recherches Médicales (DRM), Direction des Sciences du Vivant (DSV), Commissariat à l'Energie Atomique, Orsay Cedex, France.
Hermel
Jean-Michel
JM
Humbert
Sandrine
S
Jacquard
Carine
C
Créminon
Christophe
C
Escartin
Carole
C
Saudou
Frédéric
F
Krajewski
Stan
S
Hantraye
Philippe
P
Brouillet
Emmanuel
E
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism*; D002154:Calpain / Q000378:metabolism*; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D002474:Cell-Free System; D003600:Cytosol / Q000378:metabolism; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D020128:Inhibitory Concentration 50; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D019636:Neurodegenerative Diseases / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D009574:Nitro Compounds; D011422:Propionates / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D011917:Rats, Inbred Lew; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
D009574:Nitro Compounds; D011422:Propionates; D011994:Recombinant Proteins; D002154:Calpain; C505410:Casp3 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; C449002:mu-calpain; C015392:3-nitropropionic acid