An extensive β₁-adrenergic receptor gene signaling network regulates molecular remodeling in dilated cardiomyopathies

We investigated the extent, biologic characterization, phenotypic specificity, and possible regulation of a β₁-adrenergic receptor–linked (β₁-AR–linked) gene signaling network (β₁-GSN) involved in left ventricular (LV) eccentric pathologic remodeling. A 430-member β₁-GSN was identified by mRNA expression in transgenic mice overexpressing human β₁-ARs or from literature curation, which exhibited opposite directional behavior in interventricular septum endomyocardial biopsies taken from patients with beta-blocker–treated, reverse remodeled dilated cardiomyopathies. With reverse remodeling, the major biologic categories and percentage of the dominant directional change were as follows: metabolic (19.3%, 81% upregulated); gene regulation (14.9%, 78% upregulated); extracellular matrix/fibrosis (9.1%, 92% downregulated); and cell homeostasis (13.3%, 60% upregulated). Regarding the comparison of β₁-GSN categories with expression from 19,243 nonnetwork genes, phenotypic selection for major β₁-GSN categories was exhibited for LV end systolic volume (contractility measure), ejection fraction (remodeling index), and pulmonary wedge pressure (wall tension surrogate), beginning at 3 months and persisting to study completion at 12 months. In addition, 121 lncRNAs were identified as possibly involved in cisacting regulation of β₁-GSN members. We conclude that an extensive 430-member gene network downstream from the β₁-AR is involved in pathologic ventricular remodeling, with metabolic genes as the most prevalent category.