Beyond β-Adrenergic Receptor Brake: Compartment-Selective GRK2 Programs from Heart Failure to Cardio-Oncology.

Sustained neurohormonal stress, adverse myocardial remodeling, and inflammation are major components of heart failure (HF) progression. Alterations in circulating neurohormonal signaling are directly sensed by the β-adrenergic receptor (βAR), a system mainly responsible for chronotropic and inotropic cardiac responses. βARs are regulated by G-protein-coupled receptor (GPCR) kinase 2 (GRK2). Within this context, decades of study have unraveled mechanistic details on how GRK2 canonically imposes a "brake" on βARs and other GPCR-mediated signaling. Notably, an expanding body of evidence demonstrates that GRK2 functions in a highly compartment- and cell-dependent manner, with roles extending far beyond GPCR regulation. These noncanonical activities span metabolic control, maintenance of organelle integrity, and regulation of inter-cellular signaling networks, particularly those governing immune-vascular interactions. In this review, we will discuss recent advances in our understanding of the cell-specific functions of GRK2, its emerging biological roles in cardiac diseases, and the opportunities these findings present for advancing mechanistic insights in cardio-oncology. We propose that the therapeutic value of GRK2 is directly dependent on a deeper understanding of its noncanonical functions in a compartment- and cell-specific manner within a disease-specific context.