Altered Bad localization and interaction between Bad and Bcl-xL in the hippocampus after transient global ischemia.
Accumulating evidence indicates that the mitochondrial cell-death pathway, which involves the release of cytochrome c from mitochondria, participates in neuronal cell death after transient cerebral ischemia. However, the upstream events, that induce cytochrome c release after transient global ischemia are not fully understood. Bad is a pro-apoptotic member of the bcl-2 gene family that promotes apoptosis by binding to and inhibiting functions of anti-apoptotic proteins Bcl-2 and Bcl-xL. We investigated the effects of transient (15 min) global ischemia on the intracellular localization of Bad and the interaction of Bad with calcineurin, Akt or Bcl-xL in the vulnerable CA1 and resistant CA3/dentate gyrus of the hippocampus. Immunoblotting analysis revealed that the amount of Bad in mitochondria significantly increased after ischemia. Co-immunoprecipitation studies showed decreased interactions of Bad with Akt and calcineurin in the cytosol and increased binding with Bcl-xL in the mitochondrial fraction of hippocampal CA1, but not in the CA3/dentate gyrus region. Further, we examined the effect of recombinant Bad on the cytochrome c release from isolated mitochondria. Treatment with both recombinant Bad and calcium, but not with recombinant Bad alone, induced cytochrome c release. These results suggest that changes in localization and complex formation by Bad are, at least in part, involved in the vulnerability of cells after transient global ischemia.
Abe
Tsutomu
T
Faculty of Pharmaceutical Sciences, Department of Pharmacology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
Takagi
Norio
N
Nakano
Midori
M
Furuya
Mamiko
M
Takeo
Satoshi
S
D000818:Animals; D015153:Blotting, Western; D019703:Calcineurin / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006624:Hippocampus / Q000378:metabolism*; D002546:Ischemic Attack, Transient / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests / Q000379:methods; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000494:pharmacology; D015424:Reperfusion; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
C494821:Bad protein, rat; C494813:Bcl2l1 protein, rat; D002352:Carrier Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; D045304:Cytochromes c; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019703:Calcineurin; D002118:Calcium