Distinctive ERK and p38 signaling in remote and infarcted myocardium during post-MI remodeling in the mouse.
Global activation of MAP kinases has been reported in both human and experimental heart failure. Chronic remodeling of the surviving ventricular wall after myocardial infarction (MI) involves both myocyte loss and fibrosis; we hypothesized that this cardiomyopathy involves differential shifts in pro- and anti-apoptotic MAP kinase signaling in cardiac myocyte (CM) and non-myocyte. Cardiomyopathy after coronary artery ligation in mice was characterized by echocardiography, ex vivo Langendorff preparation, histologic analysis and measurements of apoptosis. Phosphorylation (activation) of signaling molecules was analyzed by Western blot, ELISA and immunohistochemistry. Post-MI remodeling involved dramatic changes in the phosphorylation of both stress-activated MAP (SAP) kinase p38 as well as ERK, a known mediator of cell survival, but not of SAP kinase JNK or the anti-apoptotic mediator of PI3K, Akt. Phosphorylation of p38 rose early after MI in the infarct, whereas a more gradual rise in the remote myocardium accompanied a rise in apoptosis in that region. In both areas, ERK phosphorylation was lowest early after MI and rose steadily thereafter, though infarct phosphorylation was consistently higher. Immunostaining of p-ERK localized to fibrotic areas populated primarily by non-myocytes, whereas staining of p38 phosphorylation was stronger in areas of progressive CM apoptosis. Relative segregation of CMs and non-myocytes in different regions of the post-MI myocardium revealed signaling patterns that imply cell type-specific changes in pro- and anti-apoptotic MAP kinase signaling. Prevention of myocyte loss and of LV remodeling after MI may therefore require cell type-specific manipulation of p38 and ERK activation.
Yeh
Che-Chung
CC
Division of Cardiothoracic Surgery, University of California, San Francisco VA Medical Center, San Francisco, CA, USA.
Li
Hongzhe
H
Malhotra
Deepak
D
Turcato
Sally
S
Nicholas
Susan
S
Tu
Richard
R
Zhu
Bo-Qing
BQ
Cha
John
J
Swigart
Philip M
PM
Myagmar
Bat-Erdene
BE
Baker
Anthony J
AJ
Simpson
Paul C
PC
Mann
Michael J
MJ
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D009202:Cardiomyopathies / Q000378:metabolism; D002478:Cells, Cultured; D004452:Echocardiography; D004797:Enzyme-Linked Immunosorbent Assay; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009203:Myocardial Infarction / Q000378:metabolism* / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D048051:p38 Mitogen-Activated Protein Kinases