Bcl-2 phosphorylation by p38 MAPK - Identification of target sites and biologic consequences
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.
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ABSTRACT: The G2019S leucine-rich repeat kinase 2 (LRRK2) mutation is the most common cause of genetic Parkinson's disease (PD). However, the molecular mechanism underlying LRRK2 G2019S-induced cellular pathology is poorly understood. Here, we demonstrated that LRRK2 G2019S bound to and phosphorylated Bcl-2, a mitochondrial anti-apoptotic protein, at Threonine 56. Either stable expression of Bcl-2 or transient expression of a Bcl-2 phosphor mutant (Bcl-2T56A) abolished LRRK2 G2019S-induced mitochondrial depolarization and autophagy. Together, our findings reveal a previously unidentified target of LRRK2 G2019S, showing that Bcl-2 serves as a point of crosstalk between LRRK2 G2019S-mediated mitochondrial disorder and dysregulation of autophagy.Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease 11/2014; DOI:10.1016/j.bbadis.2014.11.009 · 5.09 Impact Factor