Induction of apoptosis and Fas receptor/Fas ligand expression by ischemia/reperfusion in cardiac myocytes requires serine 727 of the STAT-1 transcription factor but not tyrosine 701.
Previously we reported that ischemia results in apoptosis and is accompanied by phosphorylation on Tyr-701 and increased expression and transcriptional activity of the signal transducer and activator of transcription-1 (STAT-1). In the present study, we show that exposure of cardiomyocytes to ischemia induced the phosphorylation of STAT-1 at another site, Ser-727. Moreover, STAT-1 is critical for the induction of Fas receptor and Fas ligand expression by ischemia/reperfusion (I/R). Transcriptional activation of Fas and FasL was dependent on Ser-727 of STAT-1 but was independent of Tyr-701. Similarly, Ser-727 but not Tyr-701 was required for enhancement of cardiomyocyte cell death by STAT-1 during I/R. In addition, inhibition of the p38 pathway prevented the induction and transcriptional activation of Fas and FasL in cardiac cells exposed to I/R, whereas inhibition of p42/p44 MAPK had no effect. Finally, I/R also induced phosphorylation of STAT-1 on Ser-727 and expression of Fas/FasL in ventricular myocytes in the intact heart ex vivo. These results indicate that Fas/FasL genes and apoptosis are activated by STAT-1 in cardiac myocytes exposed to I/R and these effects are dependent on the Ser-727 but not the Tyr-701 phosphorylation sites of STAT-1.
Stephanou
A
A
Medical Molecular Biology Unit, Institute of Child Health, University College London, 30 Guilford Street, London, WC1N 1EH, United Kingdom. A.Stephanou@ich.ucl.ac.uk
Scarabelli
T M
TM
Brar
B K
BK
Nakanishi
Y
Y
Matsumura
M
M
Knight
R A
RA
Latchman
D S
DS
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D015153:Blotting, Western; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053222:Fas Ligand Protein; D007093:Imidazoles / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000166:cytology*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism*; D050794:STAT1 Transcription Factor; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D015534:Trans-Activators / Q000737:chemistry; D015533:Transcriptional Activation; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry; D019014:fas Receptor / Q000096:biosynthesis*; D048051:p38 Mitogen-Activated Protein Kinases
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D007093:Imidazoles; D008562:Membrane Glycoproteins; D011725:Pyridines; D050794:STAT1 Transcription Factor; C494081:Stat1 protein, rat; D015534:Trans-Activators; D019014:fas Receptor; D014443:Tyrosine; D012694:Serine; D004247:DNA; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580