Showing papers by "Bernard M. Babior published in 1996"
TL;DR: It is concluded that acidification is an early event in programmed cell death and may be essential for genome destruction.
Abstract: We have previously shown that in neutrophils deprived of granulocyte colony-stimulating factor, apoptosis is preceded by acidification and that the protection against apoptosis conferred on neutrophils by granulocyte colony-stimulating factor is dependent upon delay of this acidification. To test the hypothesis that acidification could be a general feature of apoptosis, we examined intracellular pH changes in another cell line. Jurkat cells, a T-lymphoblastoid line, were induced to undergo apoptosis with anti-Fas IgM, cycloheximide, or exposure to short-wavelength UV light. We found that acidification occurred in response to treatment with these agents and that acidification preceded DNA fragmentation. Jurkat cells were also found to possess an acid endonuclease that is active below pH 6.8, compatible with a possible role for this enzyme in chromatin digestion during apoptosis. Incubation of the cells with the bases imidazole or chloroquine during treatment with anti-Fas antibody or cycloheximide or after UV exposure decreased apoptosis as assessed by nuclear morphology and DNA content. The alkalinizing effect of imidazole and chloroquine was shown by the demonstration that the percentage of cells with an intracellular pH below 6.8 after treatment with anti-Fas antibody, cycloheximide, or UV was diminished in the presence of base as compared with similarly treated cells incubated in the absence of base. We conclude that acidification is an early event in programmed cell death and may be essential for genome destruction.
481 citations
TL;DR: The data show that p38, like ERK, can be activated in neutrophils exposed to an appropriate stimulus, and that some but not all proline-directed kinases are able to participate in the phosphorylation of a protein essential for normal neutrophil function.
250 citations
TL;DR: These findings suggest that these three kinases play distinct roles in the activation of the respiratory burst oxidase, each of them catalyzing the phosphorylation of a different group of serines in p47phox.
233 citations
TL;DR: The results suggest that a rapid loss in mitochondrial function due at least in part to the inhibition or inactivation of cytochrome c is a potentially fatal component of the apoptosis program of Jurkat cells.
226 citations
TL;DR: It is found that BCL-2 overexpression attenuates cytoplasmic acidification and apoptosis detected by annexin V labeling and that protease activation is also upstream of acidification.
112 citations
TL;DR: Data suggest p67phox contains the catalytic NADPH-binding site of the leukocyte NADPH oxidase, as suggested by the results of partial purification of neutrophil cytosol.
Abstract: The NADPH-dependent respiratory burst oxidase of human neutrophils catalyzes the reduction of oxygen to superoxide using NADPH as the electron donor and is essential for normal host defenses. To gain insight into the function of the various oxidase subunits that are required for the full expression of catalytic activity, we studied the interactions between the 2',3'-dialdehyde derivative of NADPH (NADPH dialdehyde) and neutrophil cytosol. NADPH dialdehyde treatment of cytosol resulted in the loss of the ability of the cytosol to participate in cell-free oxidase activation; this inactivation was blocked by NADPH but not by NAD, NADP, or GTP. Partial purification of neutrophil cytosol yielded a single peak which could restore the activity lost in cytosol treated with NADPH dialdehyde. This peak contained p67phox but not p47phox or Rac2. Purified recombinant p67phox was similarly able to restore the activity lost in NADPH dialdehyde-treated cytosol and bound [32P]NADPH dialdehyde in a specific fashion. The activity of recombinant p67phox in cell-free oxidase assays was lost on treatment with NADPH dialdehyde. Together, these data suggest p67phox contains the catalytic NADPH-binding site of the leukocyte NADPH oxidase.
53 citations
Journal Article•
TL;DR: The respiratory burst oxidase of phagocytes and B lymphocytes in a multicomponent enzyme that catalyzes the reduction of oxygen by NADPH is responsible for O-(2) production in response to stimulation with phorbol 12-myristate 13-acetate (PMA) as discussed by the authors.
10 citations
TL;DR: A role for p120 is suggested as a negative regulator in the protein kinase C-mediated activation of the respiratory burst oxidase in a cell-free system.
2 citations