Document Detail

Paired activation of two components within muscarinic M3 receptor dimers is required for recruitment of beta-arrestin-1 to the plasma membrane.
MedLine Citation:
PMID:  15769745     Owner:  NLM     Status:  MEDLINE    
beta-Arrestins regulate the functioning of G protein-coupled receptors in a variety of cellular processes including receptor-mediated endocytosis and activation of signaling molecules such as ERK. A key event in these processes is the G protein-coupled receptor-mediated recruitment of beta-arrestins to the plasma membrane. However, despite extensive knowledge in this field, it is still disputable whether activation of signaling pathways via beta-arrestin recruitment entails paired activation of receptor dimers. To address this question, we investigated the ability of different muscarinic receptor dimers to recruit beta-arrestin-1 using both co-immunoprecipitation and fluorescence microscopy in COS-7 cells. Experimentally, we first made use of a mutated muscarinic M(3) receptor, which is deleted in most of the third intracellular loop (M(3)-short). Although still capable of activating phospholipase C, this receptor loses almost completely the ability to recruit beta-arrestin-1 following carbachol stimulation in COS-7 cells. Subsequently, M(3)-short was co-expressed with the M(3) receptor. Under these conditions, the M(3)/M(3)-short heterodimer could not recruit beta-arrestin-1 to the plasma membrane, even though the control M(3)/M(3) homodimer could. We next tested the ability of chimeric adrenergic muscarinic alpha(2)/M(3) and M(3)/alpha(2) heterodimeric receptors to co-immunoprecipitate with beta-arrestin-1 following stimulation with adrenergic and muscarinic agonists. beta-Arrestin-1 co-immunoprecipitation could be induced only when carbachol or clonidine were given together and not when the two agonists were supplied separately. Finally, we tested the reciprocal influence that each receptor may exert on the M(2)/M(3) heterodimer to recruit beta-arrestin-1. Remarkably, we observed that M(2)/M(3) heterodimers recruit significantly greater amounts of beta-arrestin-1 than their respective M(3)/M(3) or M(2)/M(2) homodimers. Altogether, these findings provide strong evidence in favor of the view that binding of beta-arrestin-1 to muscarinic M(3) receptors requires paired stimulation of two receptor components within the same receptor dimer.
Francesca Novi; Laura Stanasila; Franco Giorgi; Giovanni U Corsini; Susanna Cotecchia; Roberto Maggio
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-03-15
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  280     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2005 May 
Date Detail:
Created Date:  2005-05-17     Completed Date:  2005-07-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  19768-76     Citation Subset:  IM    
Department of Neurosciences, University of Pisa, Italy.
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MeSH Terms
Arrestins / metabolism*
Biological Transport, Active
COS Cells
Carbachol / pharmacology
Cell Membrane / metabolism
Cercopithecus aethiops
Clonidine / pharmacology
MAP Kinase Signaling System / drug effects
Protein Binding / drug effects
Protein Structure, Quaternary
Receptor, Muscarinic M3 / chemistry*,  genetics,  metabolism*
Receptors, Adrenergic, alpha-2 / chemistry,  genetics,  metabolism
Recombinant Fusion Proteins / chemistry,  genetics,  metabolism
Reg. No./Substance:
0/Arrestins; 0/Receptor, Muscarinic M3; 0/Receptors, Adrenergic, alpha-2; 0/Recombinant Fusion Proteins; 0/beta-arrestin; 4205-90-7/Clonidine; 51-83-2/Carbachol

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