Cascade of caspase activation in potassium-deprived cerebellar granule neurons: targets for treatment with peptide and protein inhibitors of apoptosis.
Cerebellar granule neurons (CGN) cultured in the presence of serum and depolarizing potassium concentrations undergo apoptosis when switched to serum-free medium containing physiological potassium concentrations. Here we show that processing of the key protease, caspase-3, depends on the activation of caspase-9, but not of caspase-8. Selective peptide inhibitors of caspase-9 block processing of caspase-3 and caspase-8 and inhibit apoptosis, whereas a selective inhibitor of caspase-8 blocks neither processing of caspase-3 nor cell death. The data obtained with peptide inhibitors were confirmed by adenovirally mediated ectopic expression of the cytokine response modifier A (crmA), the baculovirus protein p35, and the X chromosome-linked inhibitor of apoptosis (XIAP). Further, caspase-8-activating death receptors do not mediate apoptosis in CGN and potassium withdrawal-induced apoptosis evolves unaltered in gld or lpr mice, which harbor mutations in the CD95/CD95 ligand system. Thus, neuronal apoptosis triggered by potassium deprivation is death receptor-independent but involves the mitochondrial pathway of caspase activation.
Gerhardt
E
E
Laboratory of Neurodegeneration, University of Tübingen, Tübingen, Germany.
Kügler
S
S
Leist
M
M
Beier
C
C
Berliocchi
L
L
Volbracht
C
C
Weller
M
M
Bähr
M
M
Nicotera
P
P
Schulz
J B
JB
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology*; D003374:Coumarins / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D051034:Inhibitor of Apoptosis Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D019463:Mice, Inbred MRL lpr; D009474:Neurons / Q000166:cytology* / Q000201:enzymology*; D009842:Oligopeptides / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D011506:Proteins / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D015843:Serpins / Q000235:genetics; D013047:Specific Pathogen-Free Organisms; D019076:Transgenes / Q000502:physiology; D014764:Viral Proteins / Q000235:genetics; D051636:X-Linked Inhibitor of Apoptosis Protein
D061945:Caspase Inhibitors; D003374:Coumarins; D004791:Enzyme Inhibitors; D004792:Enzyme Precursors; D051034:Inhibitor of Apoptosis Proteins; D009842:Oligopeptides; D011506:Proteins; D015843:Serpins; D014764:Viral Proteins; D051636:X-Linked Inhibitor of Apoptosis Protein; C102580:acetyl-aspartyl-glutamyl-valyl-aspartyl-amino-4-methylcoumarin; C086430:inhibitor of apoptosis, Nucleopolyhedrovirus; C074641:interleukin-1beta-converting enzyme inhibitor; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat; C505526:Casp8 protein, mouse; C505528:Casp8 protein, rat; C506434:Casp9 protein, mouse; C506435:Casp9 protein, rat; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D011188:Potassium