Differential Cardiac Gene Regulation by Arg- and Gly389 Polymorphic Forms of the beta1-adrenergic Receptor

The beta1-adrenergic receptor (beta1AR; ADRB1) polymorphism Arg 389Gly is located in an intracellular loop and is associated with distinct human and mouse cardiovascular phenotypes. To test the hypothesis that beta1-Arg389 and beta1-Gly389 alleles could differentially couple to pathways beyond that of classic Gs-adenylyl cyclase (AC)/cAMP signaling, we performed comparative gene expression profile analyses on hearts from wildtype and transgenic mice that expressed either human beta1-Arg389 and beta1-Gly389 receptors, or AC5 adenyl cyclase, sampling at an early age and stage, prior to the onset of pathologic features. We observed substantial overlap of dysregulated genes across all three transgenic heart models, consistent with a shared coupling to cAMP-dependent regulation of cardiac processes and adaptive responses. All three models up-regulated genes associated with RNA metabolism and translation, and down-regulated genes associated with mitochondria and energy metabolism, consistent with cAMP-driven increase in cardiac contractility, protein synthesis, and compensatory down-regulation of mitochondrial energy production. Both beta1AR transgenics activated additional genes associated with kinase-dependent pathways, and uniquely, beta1-Arg389 hearts caused up-regulation of genes associated with inflammation, programmed cell death, and extracellular matrix. These results substantially expand the scope of 7-transmembrane domain receptor signaling propagation beyond known cognate G-protein couplings. Moreover, they implicate alterations of a repertoire of processes evoked by a single amino acid variation in the cardiac beta1AR that might be exploited for genotype-specific heart failure diagnostics and therapeutics.

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