Overexpression of protein kinase C isoform epsilon but not delta in human interleukin-3-dependent cells suppresses apoptosis and induces bcl-2 expression.
Hematopoietic progenitor cells die by apoptosis after removal of the appropriate colony-stimulating factor (CSF). Recent pharmacologic data have implicated protein kinase C (PKC) in the suppression of apoptosis in interleukin-3 (IL-3) and granulocyte-macrophage (GM)-CSF-dependent human myeloid cells. Because IL-3 and GM-CSF induce increases in diacylglycerol without mobilizing intracellular Ca++, it seemed that one of the novel Ca++ independent isoforms of PKC was involved. We report here that overexpression of PKC epsilon in factor-dependent human TF-1 cells extends cell survival in the absence of cytokine. Overexpression of PKC delta does not have this effect. By 72 to 96 hours after cytokine withdrawal, the PKC epsilon transfectants remain distributed in all phases of the cell cycle, as shown by fluorescence-activated cell sorting (FACS) analysis, while little intact cellular DNA is detectable in vector or PKC delta transfectants. PKC epsilon induces bcl-2 protein expression fivefold to sixfold over the levels in empty vector transfectants, whereas the levels in PKC delta transfectants are similar to those in vector controls.
Gubina
E
E
Department of Immunology, Holland Laboratory/American Red Cross, Rockville, MD 20855, USA.
Rinaudo
M S
MS
Szallasi
Z
Z
Blumberg
P M
PM
Mufson
R A
RA
D000818:Animals; D017209:Apoptosis; D002453:Cell Cycle; D002460:Cell Line; D005434:Flow Cytometry; D015870:Gene Expression; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007377:Interleukin-3 / Q000494:pharmacology*; D007527:Isoenzymes / Q000235:genetics*; D051379:Mice; D011493:Protein Kinase C / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D015398:Signal Transduction; D014162:Transfection
D007377:Interleukin-3; D007527:Isoenzymes; D019253:Proto-Oncogene Proteins c-bcl-2; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011493:Protein Kinase C