Role of the protein kinase C-epsilon-Raf-1-MEK-1/2-p44/42 MAPK signaling cascade in the activation of signal transducers and activators of transcription 1 and 3 and induction of cyclooxygenase-2 after ischemic preconditioning.
BACKGROUND
Although Janus kinase (JAK)-mediated Tyr phosphorylation of signal transducers and activators of transcription (STAT) 1 and 3 is essential for the upregulation of cyclooxygenase-2 (COX-2) and the cardioprotection of late preconditioning (PC), the role of Ser phosphorylation of STAT1 and STAT3 in late PC and the upstream signaling mechanisms responsible for mediating Ser phosphorylation of STAT1 and STAT3 remain unknown.


RESULTS
In mice preconditioned with six 4-minute coronary occlusion/4-minute reperfusion cycles, we found that (1) ischemic PC activates the Raf1-mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase kinase (MEK) 1/2-p44/42 MAPK signaling pathway, induces phosphorylation of STAT1 and STAT3 on the Ser-727 residue, and upregulates COX-2 expression; (2) pSer-STAT1 and pSer-STAT3 form complexes with pTyr-p44/42 MAPKs in preconditioned myocardium, supporting the concept that Ser phosphorylation of these 2 factors is mediated by activated p44/42 MAPKs; and (3) activation of the Raf-1-MEK-1/2-p44/42 MAPK-pSer-STAT1/3 pathway and induction of COX-2 during ischemic PC are dependent on protein kinase C (PKC)-epsilon activity, as determined by both pharmacological and genetic inhibition of PKCepsilon.


CONCLUSIONS
To our knowledge, this is the first study to demonstrate that ischemic PC causes Ser phosphorylation of STAT1 and STAT3 and that this event is governed by PKCepsilon via a PKCepsilon-Raf1-MEK1/2-p44/42 MAPK pathway. Furthermore, this is the first report that COX-2 expression in the heart is controlled by PKCepsilon. Together with our previous findings, the present study implies that STAT-dependent transcription of the genes responsible for ischemic PC is modulated by a dual signaling mechanism that involves both JAK1/2 (Tyr phosphorylation) and PKCepsilon (Ser phosphorylation).
Xuan
Yu-Ting
YT
Institute of Molecular Cardiology, University of Louisville, Louisville, KY 40292, USA.
Guo
Yiru
Y
Zhu
Yanqing
Y
Wang
Ou-Li
OL
Rokosh
Gregg
G
Messing
Robert O
RO
Bolli
Roberto
R
D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000187:drug effects / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017353:Gene Deletion; D019157:Ischemic Preconditioning, Myocardial; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D010617:Phenanthridines / Q000494:pharmacology; D010766:Phosphorylation; D051744:Protein Kinase C-epsilon / Q000235:genetics / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D050791:STAT Transcription Factors / Q000235:genetics / Q000502:physiology*; D012694:Serine; D015854:Up-Regulation
D000470:Alkaloids; D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D010617:Phenanthridines; D050791:STAT Transcription Factors; D012694:Serine; D004247:DNA; C016299:chelerythrine; D051546:Cyclooxygenase 2; D019908:Proto-Oncogene Proteins c-raf; D051744:Protein Kinase C-epsilon; D020929:Mitogen-Activated Protein Kinase Kinases