The Arf GAP AGAP2 interacts with β-arrestin2 and regulates β₂-adrenergic receptor recycling and ERK activation

AGAP2 [Arf (ADP-ribosylation factor) GAP (GTPase-activating protein) with GTP-binding-protein-like, ankyrin repeat and PH (pleckstrin homology) domains] is a multidomain Arf GAP that was shown to promote the fast recycling of transferrin receptors. In the present study we tested the hypothesis that AGAP2 regulates the trafficking of β₂-adrenergic receptors. We found that AGAP2 formed a complex with β-arrestin1 and β-arrestin2, proteins that are known to regulate β₂-adrenergic receptor signalling and trafficking. AGAP2 co-localized with β-arrestin2 on the plasma membrane, and knockdown of AGAP2 expression reduced plasma membrane association of β-arrestin2 upon β₂-adrenergic receptor activation. AGAP2 also co-localized with internalized β₂-adrenergic receptors on endosomes, and overexpression of AGAP2 slowed accumulation of β₂-adrenergic receptor in the perinuclear recycling endosomes. In contrast, knockdown of AGAP2 expression prevented the recycling of the β₂-adrenergic receptor back to the plasma membrane. In addition, AGAP2 formed a complex with endogenous ERK (extracellular-signal-regulated kinase) and overexpression of AGAP2 potentiated ERK phosphorylation induced by β₂-adrenergic receptors. Taken together, these results support the hypothesis that AGAP2 plays a role in the signalling and recycling of β₂-adrenergic receptors.