OBJECTIVE: To determine the role of prostacyclin (PGI2) in protecting endothelial cells (ECs) from apoptosis and elucidate the protective mechanism. METHODS AND RESULTS: To evaluate the effect of PGI2 on EC survival, we treated ECs with Ad-COX1/PGIS (Ad-COPI), which augmented selectively PGI2 production or carbaprostacyclin (cPGI2) followed by H2O2 for 4 hours. Ad-COPI inhibited annexin V-positive cells and blocked caspase 3 activation. cPGI2 inhibited apoptosis in a concentration-dependent manner. L-165041 had a similar effect, suggesting the involvement of peroxisome proliferator-activated receptor-delta (PPARdelta). ECs expressed functional PPARdelta. PPARdelta overexpression enhanced whereas PPARdelta knockdown by small interfering RNA abrogated the antiapoptotic action of cPGI2 and L-165041. Our results show for the first time that PGI2 stimulated 14-3-3alpha expression via PPARdelta activation. cPGI2 and L-165041 induced binding oaf PPARdelta to PPAR response elements located between -1426 and -1477 of 14-3-3alpha promoter region, thereby activating 14-3-3alpha promoter activity and protein expression. Upregulation of 14-3-3alpha proteins resulted in an increase in Bad binding to 14-3-3alpha and a reduction in Bad translocation to mitochondria. CONCLUSIONS: PGI2 protects ECs from H2O2-induced apoptosis by inducing PPARdelta binding to 14-3-3alpha promoter, thereby upregulating 14-3-3alpha protein expression. Elevated 14-3-3alpha augments Bad sequestration and prevents Bad-triggered apoptosis.
OBJECTIVE: To determine the role of prostacyclin (PGI2) in protecting endothelial cells (ECs) from apoptosis and elucidate the protective mechanism. METHODS AND RESULTS: To evaluate the effect of PGI2 on EC survival, we treated ECs with Ad-COX1/PGIS (Ad-COPI), which augmented selectively PGI2 production or carbaprostacyclin (cPGI2) followed by H2O2 for 4 hours. Ad-COPI inhibited annexin V-positive cells and blocked caspase 3 activation. cPGI2 inhibited apoptosis in a concentration-dependent manner. L-165041 had a similar effect, suggesting the involvement of peroxisome proliferator-activated receptor-delta (PPARdelta). ECs expressed functional PPARdelta. PPARdelta overexpression enhanced whereas PPARdelta knockdown by small interfering RNA abrogated the antiapoptotic action of cPGI2 and L-165041. Our results show for the first time that PGI2 stimulated 14-3-3alpha expression via PPARdelta activation. cPGI2 and L-165041 induced binding oaf PPARdelta to PPAR response elements located between -1426 and -1477 of 14-3-3alpha promoter region, thereby activating 14-3-3alpha promoter activity and protein expression. Upregulation of 14-3-3alpha proteins resulted in an increase in Bad binding to 14-3-3alpha and a reduction in Bad translocation to mitochondria. CONCLUSIONS:PGI2 protects ECs from H2O2-induced apoptosis by inducing PPARdelta binding to 14-3-3alpha promoter, thereby upregulating 14-3-3alpha protein expression. Elevated 14-3-3alpha augments Bad sequestration and prevents Bad-triggered apoptosis.
Authors: Min Young Lee; Yu Jin Lee; Yun Hee Kim; Sang Hun Lee; Jae Hong Park; Mi Ok Kim; Han Na Suh; Jung Min Ryu; Seung Pil Yun; Min Woo Jang; Ho Jae Han Journal: Int J Stem Cells Date: 2009-05 Impact factor: 2.500