Down-modulation of a novel Bax-associated protein during apoptosis in normal mature B lymphocytes.
We have recently characterized a novel 16-kDa Bax-associated protein. In this study, we investigate the regulation of this protein's expression during in vitro induction of apoptosis in mature splenic B cells. A panel of biochemically distinct apoptotic stimuli induced the dramatic down-modulation of the 16-kDa protein in B cells; this down-modulation was rapid, and did not require DNA fragmentation. Reciprocally, stimuli that induced protection from apoptosis prevented down-modulation of the 16-kDa protein. These regulatory effects were specific, since Bcl-2 and Bax protein levels were not similarly modulated. Stimuli that reduce expression of the 16-kDa protein may therefore act indirectly to increase the proapoptotic activity of Bax, perhaps by altering Bax binding to other cellular proteins.
Department of Surgery, University of Pittsburgh School of Medicine, PA 15213, USA.
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Hershberger
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McCarthy
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000276:immunology / Q000502:physiology; D002454:Cell Differentiation / Q000276:immunology; D015536:Down-Regulation / Q000276:immunology*; D005260:Female; D015847:Interleukin-4 / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism* / Q000502:physiology; D013997:Time Factors; D051028:bcl-2-Associated X Protein
C494827:Bax protein, mouse; C113548:Bax-associated protein P16, mouse; D002352:Carrier Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D015847:Interleukin-4