β-Arrestin Regulation of Myosin Light Chain Phosphorylation Promotes AT1aR-mediated Cell Contraction and Migration

Abstract

Over the last decade, it has been established that G-protein-coupled receptors (GPCRs) signal not only through canonical G-protein-mediated mechanisms, but also through the ubiquitous cellular scaffolds β-arrestin-1 and β-arrestin-2. Previous studies have implicated β-arrestins as regulators of actin reorganization in response to GPCR stimulation while also being required for membrane protrusion events that accompany cellular motility. One of the most critical events in the active movement of cells is the cyclic phosphorylation and activation of myosin light chain (MLC), which is required for cellular contraction and movement. We have identified the myosin light chain phosphatase Targeting Subunit (MYPT-1) as a binding partner of the β-arrestins and found that β-arrestins play a role in regulating the turnover of phosphorylated myosin light chain. In response to stimulation of the angiotensin Type 1a Receptor (AT1aR), MLC phosphorylation is induced quickly and potently. We have found that β-arrestin-2 facilitates dephosphorylation of MLC, while, in a reciprocal fashion, β-arrestin 1 limits dephosphorylation of MLC. Intriguingly, loss of either β-arrestin-1 or 2 blocks phospho-MLC turnover and causes a decrease in the contraction of cells as monitored by atomic force microscopy (AFM). Furthermore, by employing the β-arrestin biased ligand [Sar1,Ile4,Ile8]-Ang, we demonstrate that AT1aR-mediated cellular motility involves a β-arrestin dependent component. This suggests that the reciprocal regulation of MLC phosphorylation status by β-arrestins-1 and 2 causes turnover in the phosphorylation status of MLC that is required for cell contractility and subsequent chemotaxic motility.

Signaling Mechanism Underlying the Promotion of Keratinocyte Migration by Angiotensin II

“…We now show that b-arrestin-dependent signaling, but not G protein-dependent signaling, downstream of AT 1 R mediates the stimulatory effect of angiotensin II on keratinocyte migration. Forced expression of mouse AT 1 R (AT 1a R) in heterologous cells previously implicated b-arrestin in AT 1a R-dependent cellular motility (Hunton et al, 2005;Simard et al, 2013).…”

Label-Free Monitoring ofμ-Opioid Receptor–Mediated Signaling

“…Based on previous studies from our group (Cuerrier et al, 2008;Simard et al, 2013), we propose that an important contribution to the SPR signal after stimulation with MOP agonists, as well as MOP so-called antagonists, could be due to a Ga i -and ERK1/ERK2-dependent actin cytoskeleton rearrangement. Accordingly, our results revealed an important role of ERK1/ERK2 and Ga i in the generation of the SPR signal evoked by the activation of MOP.…”

Inhibition of 5‐Hydroxytryptamine Receptor 2B Reduced Vascular Restenosis and Mitigated the β‐Arrestin2–Mammalian Target of Rapamycin/p70S6K Pathway

“…β‐Arrestins can act as positive mediators for signaling, leading to activation of protein kinases, such as Src, MAPKs, and phosphatidylinositol 3‐kinase–protein kinase B 40. It was reported that β‐arrestins can regulate myosin light chain phosphorylation to promote the motility of SMC 68. β‐Arrestin2 mediates angiotensin II–induced SMC migration in such a manner 41.…”