期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2001
卷号：98
期号：16
页码：9050-9055
DOI：10.1073/pnas.161283798
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The goal of this study was to determine the role of the Janus tyrosine kinase (JAK)-signal transducers and activators of transcription (STAT) pathway in the late phase of ischemic preconditioning (PC). A total of 230 mice were used. At 5 min after ischemic PC (induced with six cycles of 4-min coronary occlusion/4-min reperfusion), immunoprecipitation with anti-phosphotyrosine (anti-pTyr) antibodies followed by immunoblotting with anti-JAK antibodies revealed increased tyrosine phosphorylation of JAK1 (+257 {+/-} 53%) and JAK2 (+238 {+/-} 35%), indicating rapid activation of these two kinases. Similar results were obtained by immunoblotting with anti-pTyr-JAK1 and anti-pTyr-JAK2 antibodies. Western analysis with anti-pTyr-STAT antibodies demonstrated a marked increase in nuclear pTyr-STAT1 (+301 {+/-} 61%) and pTyr-STAT3 (+253 {+/-} 60%) 30 min after ischemic PC, which was associated with redistribution of STAT1 and STAT3 from the cytosolic to the nuclear fraction and with an increase in STAT1 and STAT3 {gamma}-IFN activation site DNA-binding activity (+606 {+/-} 64%), indicating activation of STAT1 and STAT3. No nuclear translocation or tyrosine phosphorylation of STAT2, STAT4, STAT5A, STAT5B, or STAT6 was observed. Pretreatment with the JAK inhibitor AG-490 20 min before the six occlusion/reperfusion cycles blocked the enhanced tyrosine phosphorylation of JAK1 and JAK2 and the increased tyrosine phosphorylation, nuclear translocation, and enhanced DNA-binding activity of STAT1 and STAT3. The same dose of AG-490 abrogated the protection against myocardial infarction and the concomitant up-regulation of inducible NO synthase (iNOS) protein and activity observed 24 h after ischemic PC. Taken together, these results demonstrate that ischemic PC induces isoform-selective activation of JAK1, JAK2, STAT1, and STAT3, and that ablation of this response impedes the up-regulation of iNOS and the concurrent acquisition of ischemic tolerance. This study demonstrates that the JAK-STAT pathway plays an essential role in the development of late PC. The results reveal a signaling mechanism that underlies the transcriptional up-regulation of the cardiac iNOS gene and the adaptation of the heart to ischemic stress.
