Canonical or non-canonical, all aspects of G protein-coupled receptor kinase 2 in heart failure.

G protein-coupled receptor kinase 2 (GRK2) with its multidomain structure performs various crucial cellular functions under both normal and pathological conditions. Overexpression of GRK2 is linked to cardiovascular diseases, and its inhibition or deletion has been shown to be protective. The functions of GRK2 extend beyond G protein-coupled receptor (GPCR) signaling, influencing non-GPCR substrates as well. Increased GRK2 in heart failure (HF) initially may be protective but ultimately leads to maladaptive effects such as GPCR desensitization, insulin resistance, and apoptosis. The multifunctional nature of GRK2, including its action in hypertrophic gene expression, insulin signaling, and cardiac fibrosis, highlights its complex role in HF pathogenesis. Additionally, GRK2 is involved in mitochondrial biogenesis and lipid metabolism. GRK2 also regulates epinephrine secretion from the adrenal gland and its increase in circulating lymphocytes can be used to monitor HF status. Overall, GRK2 is a multifaceted protein with significant implications for HF and the regulation of GRK2 is crucial for understanding and treating cardiovascular diseases.