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KMID : 0578320070240020224
Molecules and Cells
2007 Volume.24 No. 2 p.224 ~ p.231
Regulation of BAD Protein by PKA, PKC¥ä and Phosphatases in Adult Rat Cardiac Myocytes Subjected to Oxidative Stress
Cieslak Danuta

Lazou Antigone
Abstract
H2O2, as an example of oxidative stress, induces cardiac myocyte apoptosis. Bcl-2 family proteins are key regulators of the apoptotic response while their functions can be regulated by post-translational modifications including phosphorylation, dimerization or proteolytic cleavage. In this study, we examined the role of various protein kinases in regulating total BAD protein levels in adult rat cardiac myocytes undergoing apoptosis. Stimulation with 0.1 mM H2O2, which induces apoptosis, resulted in a marked down-regulation of BAD protein, which is attributed to cleavage by caspases since it can be restored in the presence of a general caspase inhibitor. Inhibition of PKC, p38-MAPK, ERK1/2 and PI-3-K did not influence the reduced BAD protein levels observed after stimulation with H2O2. On the contrary, inhibition of PKA or specifically PKC¥ä resulted in up-regulation of BAD. Decreased caspase 3 activity was observed in H2O2 treated cells after inhibition of PKA or PKC¥ä whereas inhibition of PKA also resulted in improved cell survival. Furthermore, addition of okadaic acid to inhibit selected phosphatases resulted in enhanced BAD cleavage. These data suggest that, during oxidative stress-induced cardiac myocyte apoptosis, there is a caspase-dependent down-regulation of BAD protein, which seems to be regulated by coordinated action of PKA, PKC¥ä and phosphatases
KEYWORD
Apoptosis, BAD, Cardiac Myocyte, H2O2, Phosphatase, Protein Kinase.
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