Higher levels of betaARK1 inhibition via betaARKct expression preserved fractional shortening and beta-adrenergic receptor density in mice at 12 weeks after transverse aortic constriction.
Does the level of betaARK1 inhibition determine the degree of cardiac dysfunction after chronic pressure overload-induced heart failure in mice?
The degree of betaARK1 inhibition directly correlates with the preservation of cardiac function in a pressure overload model, supporting its potential as a therapeutic target in heart failure.
BACKGROUND: Heart failure is characterized by abnormalities in beta-adrenergic receptor (betaAR) signaling, including increased level of myocardial betaAR kinase 1 (betaARK1). Our previous studies have shown that inhibition of betaARK1 with the use of the Gbetagamma sequestering peptide of betaARK1 (betaARKct) can prevent cardiac dysfunction in models of heart failure. Because inhibition of betaARK activity is pivotal for amelioration of cardiac dysfunction, we investigated whether the level of betaARK1 inhibition correlates with the degree of heart failure. METHODS AND RESULTS: Transgenic (TG) mice with varying degrees of cardiac-specific expression of betaARKct peptide underwent transverse aortic constriction (TAC) for 12 weeks. Cardiac function was assessed by serial echocardiography in conscious mice, and the level of myocardial betaARKct protein was quantified at termination of the study. TG mice showed a positive linear relationship between the level of betaARKct protein expression and fractional shortening at 12 weeks after TAC. TG mice with low betaARKct expression developed severe heart failure, whereas mice with high betaARKct expression showed significantly less cardiac deterioration than wild-type (WT) mice. Importantly, mice with a high level of betaARKct expression had preserved isoproterenol-stimulated adenylyl cyclase activity and normal betaAR densities in the cardiac membranes. In contrast, mice with low expression of the transgene had marked abnormalities in betaAR function, similar to the WT mice. CONCLUSIONS: These data show that the level of betaARK1 inhibition determines the degree to which cardiac function can be preserved in response to pressure overload and has important therapeutic implications when betaARK1 inhibition is considered as a molecular target.
Tachibana et al. (2005) studied Heart failure. betaARKct peptide expression vs. Wild-type (WT) mice was evaluated on Fractional shortening. Higher levels of betaARK1 inhibition via betaARKct expression preserved fractional shortening and beta-adrenergic receptor density in mice at 12 weeks after transverse aortic constriction.