Published online before print October 26, 2006, doi: 10.1161/01.RES.0000251074.19348.af
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Submitted on January 27, 2006
Revised on October 12, 2006
Accepted on October 16, 2006
Small Heat-Shock Protein Hsp20 Attenuates 
-Agonist-Mediated Cardiac Remodeling Through Apoptosis Signal-Regulating Kinase 1
Guo-Chang Fan ;
From the Departments of Pharmacology and Cell Biophysics (G.-C.F., Q.Y., G.C., J.Q., X.Z., E.G.K.) and Pathology and Laboratory Medicine (Y.W., MA.), University of Cincinnati College of Medicine, Ohio; Department of Cardiology (G.S.), 2nd Clinical School of Yangzhou University Medical College, China; Department of Surgery and Pharmacology (Y.J.L.), University of Pittsburgh, Pa; and Molecular Biology Division (E.G.K.), Center for Basic Research, Foundation for Biomedical Research of the Academy of Athens, Greece.
* To whom correspondence should be addressed. E-mail: Litsa.Kranias{at}uc.edu.
Chronic stimulation of the 
-adrenergic neurohormonal axis contributes to the progression of heart failure and mortality in animal models and human patients. In cardiomyocytes, activation of the -adrenergic pathway has been shown to result in transiently increased expression of a cardiac small heat-shock protein Hsp20. The present study shows that cardiac overexpression (10-fold) of Hsp20 may protect the heart against -agonist-induced cardiac remodeling, associated with isoproterenol (50 µg/g per day) infusion for 14 days. Hsp20 attenuated the cardiac hypertrophic response, markedly reduced interstitial fibrosis, and decreased apoptosis. Contractility was also preserved in hearts with increased Hsp20 levels. These beneficial effects were associated with attenuation of the ASK1-JNK/p38 (apoptosis signal-regulating kinase 1/c-Jun NH2-terminal kinase/p38) signaling cascade triggered by isoproterenol, whereas there was no difference in either extracellular signal-related kinase 1/2 or Akt activation. Parallel in vitro experiments supported the inhibitory role of Hsp20 on enforced ASK1-JNK/p38 activation in both H9c2 cells and adult rat cardiomyocytes. Immunostaining studies also demonstrated that Hsp20 colocalizes with ASK1 in cardiomyocytes. Taken together, our findings indicate that (1) -agonist-induced cardiac injury is associated with activation of the ASK1-JNK/p38 cascade; (2) increased expression of Hsp20 attenuates the induction of remodeling, dysfunction, and apoptosis in response to sustained -adrenergic stimulation; and (3) the beneficial effects of Hsp20 are at least partially attributable to inhibition of the ASK1-signaling cascade.
Key words: small heat-shock protein Hsp20 • apoptosis •
-adrenergic receptor •
apoptosis signal-regulating kinase 1 (ASK1)
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