Determining the Effects of Differential Expression of GRKs and β-arrestins on CLR-RAMP Agonist Bias.


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Authors
Redfern-Nichols, Theo 
Harris, Matthew 
Poyner, David R 
Wigglesworth, Mark 
Abstract

Signalling of the calcitonin-like receptor (CLR) is multifaceted, due to its interaction with receptor activity modifying proteins (RAMPs), and three endogenous peptide agonists. Previous studies have focused on the bias of G protein signalling mediated by the receptor and receptor internalisation of the CLR-RAMP complex has been assumed to follow the same pattern as other Class B1 G Protein-Coupled Receptors (GPCRs). Here we sought to measure desensitisation of the three CLR-RAMP complexes in response to the three peptide agonists, through the measurement of β-arrestin recruitment and internalisation. We then delved further into the mechanism of desensitisation through modulation of β-arrestin activity and the expression of GPCR kinases (GRKs), a key component of homologous GPCR desensitisation. First, we have shown that CLR-RAMP1 is capable of potently recruiting β-arrestin1 and 2, subsequently undergoing rapid endocytosis, and that CLR-RAMP2 and -RAMP3 also utilise these pathways, although to a lesser extent. Following this we have shown that agonist-dependent internalisation of CLR is β-arrestin dependent, but not required for full agonism. Overexpression of GRK2-6 was then found to decrease receptor signalling, due to an agonist-independent reduction in surface expression of the CLR-RAMP complex. These results represent the first systematic analysis of the importance of β-arrestins and GRKs in CLR-RAMP signal transduction and pave the way for further investigation regarding other Class B1 GPCRs.

Description
Keywords
Physiology, GPCRs (G protein-coupled receptors), signalling bias, CLR, β-arrestins, RAMPs, internalisation, GRK (G protein receptor kinase)
Journal Title
Front Physiol
Conference Name
Journal ISSN
1664-042X
1664-042X
Volume Title
13
Publisher
Frontiers Media SA
Sponsorship
BBSRC (BB/V509334/1)