Phosphatidylinositol 3-Kinase/Akt Signaling Controls Endothelial Cell Sensitivity to Fas-Mediated Apoptosis via Regulation of FLICE-Inhibitory Protein (FLIP)
作者:
Toshimitsu Suhara,
Toshiaki Mano,
Beatriz Oliveira,
Kenneth Walsh,
期刊:
Circulation Research: Journal of the American Heart Association
(OVID Available online 2001)
卷期:
Volume 89,
issue 1
页码: 13-19
ISSN:0009-7330
年代: 2001
出版商: OVID
关键词: apoptosis;cell signaling;signal transduction;growth factors;cytokines
数据来源: OVID
摘要:
Abstract—Fas is constitutively expressed on endothelial cells, but in contrast to smooth muscle and other cell types, endothelial cells are highly resistant to Fas-mediated apoptosis. In this study, we examined the role of the serine/threonine kinase Akt/PKB in controlling the sensitivity of endothelial cells to Fas-mediated apoptosis. Serum deprivation inhibited expression of the caspase-8 inhibitor FLICE-inhibitory protein (FLIP), which functions downstream from Fas. FLIP expression levels were restored when serum-depleted cells were treated with vascular endothelial growth factor. Treatment with the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitors wortmannin or LY294002 or infection of the adenoviral construct expressing dominant-negative Akt (Adeno-dnAkt) also inhibited the expression of FLIP in endothelial cells, whereas the MEK inhibitor PD98059 had no effect. Conversely, adenovirus-mediated transfection of a constitutively-activeAktgene abolished the wortmannin- and LY294002-mediated downregulation of FLIP. Suppression of PI 3-kinase signaling sensitized endothelial cells to Fas-mediated apoptosis. Under conditions of suppressed PI 3-kinase signaling, restoration of FLIP expression reversed the induced sensitivity of endothelial cells to Fas-mediated apoptosis. These data suggest that inhibition of Fas-mediated apoptosis, via promotion of FLIP expression, is a mechanism through which Akt signaling can promote endothelial cell survival.
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