Past and present of beta arrestins: A new perspective on insulin secretion and effect

BACKGROUND: Beta arrestins had been known as intracellular adaptors that uncouple and inactivate the G protein-coupled receptors that they interact with. Their roles as signal initiators for some receptors have recently been recognized. SCOPE OF REVIEW: In this review, we focused on their role in mediating metabolic modulation primarily in relation to insulin signaling. Commenced by the upstream receptor, they seem to act like intracellular hubs that divert the metabolic profile of the cell. The amount of metabolic substrates in circulation and their usage/deposition by tissues are controlled by the contribution of all systems in the organism. This control is enabled by the release of hormones such as insulin, glucagon and glucagon-like peptide-1. Intriguingly, some ligands -either agonists or antagonists-of different classes of receptors have preferential properties mediated by β arrestins. This is not surprizing considering that substrate supply and usage should parallel physiological function such as hormone release or muscle contraction. MAJOR CONCLUSIONS: Available data indicate that β arrestins conduct the regulatory role in insulin secretion and action. They may be good candidates to target when the upstream signal demands the function that may compromise the cell. An example is carvedilol that is protective by preventing the stimulatory effects of excessive catecholamines, stimulates mitochondrial function and has preferential clinical outcomes in metabolic disorders.