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(Circulation Research. 2008;102:1025.)
© 2008 American Heart Association, Inc.

Molecular Medicine

Activation of Notch-Mediated Protective Signaling in the Myocardium

Natalie A. Gude, Gregory Emmanuel, Weitao Wu, Christopher T. Cottage, Kimberlee Fischer, Pearl Quijada, John A. Muraski, Roberto Alvarez, Marta Rubio, Eric Schaefer, Mark A. Sussman

From the San Diego State University Heart Institute (N.A.G., G.E., W.W., C.T.C., K.F., P.Q., J.A.M., R.A., M.R., M.A.S.), Department of Biology, San Diego State University, Calif; and Biosource International (E.S.), Hopkinton, Mass.

Correspondence to Mark A. Sussman, San Diego State University, 5500 Campanile Dr, San Diego, CA 92182. E-mail sussman{at}heart.sdsu.edu

The Notch network regulates multiple cellular processes, including cell fate determination, development, differentiation, proliferation, apoptosis, and regeneration. These processes are regulated via Notch-mediated activity that involves hepatocyte growth factor (HGF)/c-Met receptor and phosphatidylinositol 3-kinase/Akt signaling cascades. The impact of HGF on Notch signaling was assessed following myocardial infarction as well as in cultured cardiomyocytes. Notch1 is activated in border zone cardiomyocytes coincident with nuclear c-Met following infarction. Intramyocardial injection of HGF enhances Notch1 and Akt activation in adult mouse myocardium. Corroborating evidence in cultured cardiomyocytes shows treatment with HGF or insulin increases levels of Notch effector Hes1 in immunoblots, whereas overexpression of activated Notch intracellular domain prompts a 3-fold increase in phosphorylated Akt. Infarcted hearts injected with adenoviral vector expressing Notch intracellular domain treatment exhibit improved hemodynamic function in comparison with control mice after 4 weeks, implicating Notch signaling in a cardioprotective role following cardiac injury. These results indicate Notch activation in cardiomyocytes is mediated through c-Met and Akt survival signaling pathways, and Notch1 signaling in turn enhances Akt activity. This mutually supportive crosstalk suggests a positive survival feedback mechanism between Notch and Akt signaling in adult myocardium following injury.

Key Words: Notch • Akt • cardioprotection • infarction • myocardium

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