title: An essential role of the JAK-STAT pathway in ischemic preconditioning.
abstract: 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.
authors.affiliation: Experimental Research Laboratory, Division of Cardiology, University of Louisville and the Jewish Hospital Heart and Lung Institute, Louisville, KY 40292, USA.
authors.forename: Y T
authors.initials: YT
authors.lastname: Xuan
authors.forename: Y
authors.initials: Y
authors.lastname: Guo
authors.forename: H
authors.initials: H
authors.lastname: Han
authors.forename: Y
authors.initials: Y
authors.lastname: Zhu
authors.forename: R
authors.initials: R
authors.lastname: Bolli
mesh_terms: D000818:Animals; D001483:Base Sequence; D015342:DNA Probes; D019194:Ischemic Preconditioning; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009203:Myocardial Infarction / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D015342:DNA Probes; D015534:Trans-Activators; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D019001:Nitric Oxide Synthase; D011505:Protein-Tyrosine Kinases