Modulation of Bcl-2 family proteins in primary endothelial cells during apoptosis.
We studied the expression of Bcl-2 family proteins during cytokine- and verotoxin (VT)-induced apoptosis in primary human umbilical vein endothelial cells (HUVECs). Our experiments demonstrated that high initial expression of Bcl-2 protein was significantly downregulated in HUVECs treated with IFN-gamma whereas TNF-alpha gave a less pronounced decrease in Bcl-2 level. Treatment with the combination of cytokines was more efficient in downregulating Bcl-2 protein. HUVECs pretreated with cytokines and incubated with VT gave a further significant decrease in Bcl-2 level. Simultaneous measurement of Bcl-xl level did not reveal any significant changes. Bax protein was upregulated in HUVECs stimulated with TNF-alpha alone or in combination with IFN-gamma. However, addition of VT did not give any further increase in Bax level suggesting that Bax upregulation is more important for cytokine- rather than VT-mediated apoptosis. Total endothelial cell growth factor deprivation gave a significant increase in apoptosis accompanied by a decrease of Bcl-2 in apoptotic cells while Bcl-xl and Bax levels were unaffected. Our data indicate that anti-apoptotic protein Bcl-2 and pro-apoptotic protein Bax are reciprocally regulated during apoptosis, whilst Bcl-xl is essentially unaffected. This implies that Bcl-2/Bax ratio rather than Bcl-xl controls apoptosis in primary endothelial cells.
Molostvov
G
G
Department of Biological Sciences, University of Warwick, Coventry, UK. gmolostvov@bio.warwick.ac.uk
Morris
A
A
Rose
P
P
Basu
S
S
D017209:Apoptosis / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D016228:Endothelial Growth Factors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000502:physiology; D022603:Shiga Toxins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014471:Umbilical Veins; D015854:Up-Regulation / Q000187:drug effects; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
C494826:BAX protein, human; C494811:BCL2L1 protein, human; D016228:Endothelial Growth Factors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D022603:Shiga Toxins; D014409:Tumor Necrosis Factor-alpha; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D007371:Interferon-gamma