Myostatin-null mice exhibited more exuberant cardiomyocyte growth in response to chronic phenylephrine infusion compared to littermate controls, corresponding with increased p38 and Akt activation.
Myostatin acts as a negative regulator of cardiomyocyte growth in response to hypertrophic stimuli via inhibition of p38 and Akt signaling.
Myostatin is a highly conserved, potent negative regulator of skeletal muscle hypertrophy in many species, from rodents to humans, although its mechanisms of action are incompletely understood. Transcript profiling of hearts from a genetic model of cardiac hypertrophy revealed dramatic upregulation of myostatin, not previously recognized to play a role in the heart. Here we show that myostatin abrogates the cardiomyocyte growth response to phenylephrine in vitro through inhibition of p38 and the serine-threonine kinase Akt, a critical determinant of cell size in many species from drosophila to mammals. Evaluation of male myostatin-null mice revealed that their cardiomyocytes and hearts overall were slightly smaller at baseline than littermate controls but exhibited more exuberant growth in response to chronic phenylephrine infusion. The increased cardiac growth in myostatin-null mice corresponded with increased p38 phosphorylation and Akt activation in vivo after phenylephrine treatment. Together, these data demonstrate that myostatin is dynamically regulated in the heart and acts more broadly than previously appreciated to regulate growth of multiple types of striated muscle.
Morissette et al. (Fri,) conducted a other in Cardiac hypertrophy. Myostatin deletion (myostatin-null) vs. Littermate controls was evaluated on Cardiomyocyte growth response to phenylephrine. Myostatin-null mice exhibited more exuberant cardiomyocyte growth in response to chronic phenylephrine infusion compared to littermate controls, corresponding with increased p38 and Akt activation.
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