Changes in bad phosphorylation are correlated with BCR-induced apoptosis of WEHI-231 immature B cells.
Signaling through the B cell antigen receptor (BCR) is a key determinant in the regulation of B cell physiology. Depending on additional factors, such as microenvironment and developmental stage, ligation of the BCR can trigger B lymphocyte activation, proliferation, or apoptosis. The regulatory mechanisms determining B cell apoptosis and survival are not completely known. Using the murine B lymphoma cell line WEHI-231 as a model system, we investigated the role of Bad phosphorylation, a pro-apoptotic member of the Bcl-2 family, in anti-IgM mediated apoptosis. For apoptotic analysis we focused in particular on the mitochondrial potential (deltapsi(m)) collapse which has been reported as a rate-limiting step in the BCR-induced cell death of immature B lymphocytes. Bad phosphorylation at serine 112, 136 and 155 was found in WEHI-231 cell control cultures and its hypophosphorylation on the three sites correlated with the appearance of apoptosis when cross-linking surface IgM. Furthermore, treatment of cells with specific PK inhibitors known to be involved in serine phosphorylation of Bad (LY294002 for PI3K and H-89 for PKA) mimiced or enhanced BCR-induced cell death. These results strongly suggest that regulation of Bad phosphorylation plays an active role in mediating anti-IgM-induced apoptosis of immature B cells.
Laboratoire de physiologie moléculaire mitochondriale et immunitaire, faculté de médecine, UMR CNRS 6101, 2, rue du Dr Marcland, 87025 Limoges cedex, France.
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Malissein
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Verdier
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Ratinaud
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Troutaud
D048948:14-3-3 Proteins; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001402:B-Lymphocytes / Q000378:metabolism* / Q000473:pathology*; D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007075:Immunoglobulin M / Q000378:metabolism; D007546:Isoquinolines / Q000494:pharmacology; D016393:Lymphoma, B-Cell; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D013449:Sulfonamides; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
D048948:14-3-3 Proteins; D002352:Carrier Proteins; D002867:Chromones; D017868:Cyclic AMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D007075:Immunoglobulin M; D007546:Isoquinolines; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D011947:Receptors, Antigen, B-Cell; D012694:Serine; D013449:Sulfonamides; D014446:Tyrosine 3-Monooxygenase; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; C494820:Bad protein, mouse; C494812:Bcl2l1 protein, mouse; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide