Calcium-dependent interaction of calcineurin with Bcl-2 in neuronal tissue.
Calcineurin, a calmodulin-dependent protein phosphatase, regulates transcription and possibly apoptosis. Previous studies demonstrated that in baby hamster kidney-21 cells after co-transfection calcineurin interacts with Bcl-2, thereby altering transcription and apoptosis. Using co-immunoprecipitation and subcellular fractionation techniques, we observed that calcineurin occurred as a complex with Bcl-2 in various regions of rat and mouse brain. The calcineurin-Bcl-2 complex was identified in mitochondrial, nuclear, microsomal and cytosol fractions. In vitro induction of hypoxia and aglycia or N-methyl-D-aspartate treatment markedly altered both extent of complex formation and its subcellular localization. These observations suggest that Bcl-2 either sequesters calcineurin, that calcineurin dephosphorylates Bcl-2, or that Bcl-2 shuttles calcineurin to specific substrates. Calcineurin also co-immunoprecipitated with the inositol-tris-phosphate receptor. This interaction increased after in vitro hypoxia/aglycia. In Bcl-2 (-/-) mice, interactions between calcineurin- and inositol-tris-phosphate receptor occurred less frequently than in wild-type mice under both control and hypoxic conditions. Experiments involving cell-free systems, as well as brain slices treated with thapsigargin or with N-methyl-D-aspartate suggested that calcium and calmodulin activation of calcineurin leads to interactions between calcineurin and Bcl-2. These data indicate that during times of cellular stress and damage, Bcl-2 targets activated calcineurin to specific compartments and substrates.
Erin
N
N
Department of Pharmacology, H078, 500 University Drive, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA.
Bronson
S K
SK
Billingsley
M L
ML
D000818:Animals; D015153:Blotting, Western / Q000379:methods; D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002147:Calmodulin / Q000494:pharmacology; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D003433:Crosses, Genetic; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D020925:Hypoxia-Ischemia, Brain / Q000378:metabolism / Q000503:physiopathology; D066298:In Vitro Techniques; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008297:Male; D051379:Mice; D018345:Mice, Knockout / Q000378:metabolism; D008822:Mice, Transgenic / Q000378:metabolism; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011233:Precipitin Tests / Q000379:methods; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects / Q000378:metabolism; D013347:Subcellular Fractions / Q000145:classification / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors
D015220:Calcium Channels; D002147:Calmodulin; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D053496:Inositol 1,4,5-Trisphosphate Receptors; D019253:Proto-Oncogene Proteins c-bcl-2; D018160:Receptors, Cytoplasmic and Nuclear; D016202:N-Methylaspartate; D019284:Thapsigargin; D019703:Calcineurin; D002118:Calcium