1. Bcl-2 Phosphorylation by p38 MAPK: identification of target sites and biologic consequences.
- Author
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De Chiara G, Marcocci ME, Torcia M, Lucibello M, Rosini P, Bonini P, Higashimoto Y, Damonte G, Armirotti A, Amodei S, Palamara AT, Russo T, Garaci E, and Cozzolino F
- Subjects
- Animals, Caspases metabolism, Cytochromes c chemistry, Dogs, Enzyme Activation, Humans, MAP Kinase Signaling System, Mice, Mice, Knockout, Peptides chemistry, bcl-2-Associated X Protein metabolism, fas Receptor metabolism, Proto-Oncogene Proteins c-bcl-2 metabolism, p38 Mitogen-Activated Protein Kinases metabolism
- Abstract
The antiapoptotic role of Bcl-2 can be regulated by its phosphorylation in serine and threonine residues located in a nonstructured loop that links BH3 and BH4 domains. p38 MAPK has been identified as one of the kinases able to mediate such phosphorylation, through direct interaction with Bcl-2 protein in the mitochondrial compartment. In this study, we identify, by using mass spectrometry techniques and specific anti-phosphopeptide antibodies, Ser(87) and Thr(56) as the Bcl-2 residues phosphorylated by p38 MAPK and show that phosphorylation of these residues is always associated with a decrease in the antiapoptotic potential of Bcl-2 protein. Furthermore, we obtained evidence that p38 MAPK-induced Bcl-2 phosphorylation plays a key role in the early events following serum deprivation in embryonic fibroblasts. Both cytochrome c release and caspase activation triggered by p38 MAPK activation and Bcl-2 phosphorylation are absent in embryonic fibroblasts from p38alpha knock-out mice (p38alpha(-/-) MEF), whereas they occur within 12 h of serum withdrawal in p38alpha(+/+) MEF; moreover, they can be prevented by p38 MAPK inhibitors and are not associated with the synthesis of the proapoptotic proteins Bax and Fas. Thus, Bcl-2 phosphorylation by activated p38 MAPK is a key event in the early induction of apoptosis under conditions of cellular stress.
- Published
- 2006
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