Caspase-3 expression by cerebellar granule neurons is regulated by calcium and cyclic AMP.
Caspase-3 enzyme activity is induced, and cell death follows, when cerebellar granule neurons (CGNs) from 8-day-old rats are transferred from an extracellular concentration of 25 mM K+ (25 mM [K+]e) to 5 mM [K+]e. Death of these neurons is diminished by an inhibitor of caspase-3 but not by an inhibitor of caspase-1. Actinomycin D and cycloheximide inhibit induction of caspase-3 and prevent death. Experiments in which CGN intracellular Ca2+ concentration ([Ca2+]i) was manipulated by either changing [K+]e or adding a voltage-gated Ca2+ channel antagonist or a Ca2+ ionophore to the medium showed that caspase-3 mRNA rises 2.5-fold when [Ca2+]i is diminished from 300 to 150 nM, with a corresponding rise in peak caspase enzyme activity. Whereas the caspase-3 mRNA level does not rise further with a still greater diminution in [Ca2+]i, peak caspase enzyme activity continues to increase, reaching sevenfold induction when [Ca2+]i is reduced to 55 nM. In CGNs in which [Ca2+]i is set at 55 nM by incubation in 5 mM [K+]e, treatment with forskolin or dibutyryl 3',5'-cyclic adenosine-5'-monophosphate delays caspase-3 induction and diminishes death but does not alter [Ca2+]i. We conclude that, in immature CGNs, both caspase-3 transcription and the subsequent processing of caspase-3 are induced by a fall in [Ca2+]i. Elevating cyclic AMP content delays caspase-3 induction by a mechanism that does not require an increase in [Ca2+]i.
Moran
J
J
Institute of Cell Physiology, National University of Mexico, Mexico City.
Itoh
T
T
Reddy
U R
UR
Chen
M
M
Alnemri
E S
ES
Pleasure
D
D
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D053148:Caspase 3; D020169:Caspases / Q000235:genetics*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D005576:Colforsin / Q000494:pharmacology; D003374:Coumarins / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000201:enzymology*; D009842:Oligopeptides / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D014158:Transcription, Genetic / Q000502:physiology
C112287:Ac-aspartyl-glutamyl-valyl-aspartyl-aminomethylcoumarin; D000590:Amino Acid Chloromethyl Ketones; D003374:Coumarins; D015853:Cysteine Proteinase Inhibitors; D009842:Oligopeptides; D011500:Protein Synthesis Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D003609:Dactinomycin; D005576:Colforsin; D003994:Bucladesine; D003513:Cycloheximide; D000242:Cyclic AMP; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D011188:Potassium; D002118:Calcium