title: β-arrestin promotes Wnt-induced low density lipoprotein receptor-related protein 6 (Lrp6) phosphorylation via increased membrane recruitment of Amer1 protein.
abstract: β-Arrestin is a scaffold protein that regulates signal transduction by seven transmembrane-spanning receptors. Among other functions it is also critically required for Wnt/β-catenin signal transduction. In the present study we provide for the first time a mechanistic basis for the β-arrestin function in Wnt/β-catenin signaling. We demonstrate that β-arrestin is required for efficient Wnt3a-induced Lrp6 phosphorylation, a key event in downstream signaling. β-Arrestin regulates Lrp6 phosphorylation via a novel interaction with phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2)-binding protein Amer1/WTX/Fam123b. Amer1 has been shown very recently to bridge Wnt-induced and Dishevelled-associated PtdIns(4,5)P2 production to the phosphorylation of Lrp6. Using fluorescence recovery after photobleaching we show here that β-arrestin is required for the Wnt3a-induced Amer1 membrane dynamics and downstream signaling. Finally, we show that β-arrestin interacts with PtdIns kinases PI4KIIα and PIP5KIβ. Importantly, cells lacking β-arrestin showed higher steady-state levels of the relevant PtdInsP and were unable to increase levels of these PtdInsP in response to Wnt3a. In summary, our data show that β-arrestins regulate Wnt3a-induced Lrp6 phosphorylation by the regulation of the membrane dynamics of Amer1. We propose that β-arrestins via their scaffolding function facilitate Amer1 interaction with PtdIns(4,5)P2, which is produced locally upon Wnt3a stimulation by β-arrestin- and Dishevelled-associated kinases.
authors.affiliation: From the Faculty of Science, Institute of Experimental Biology, Masaryk University, 611 37 Brno, Czech Republic.
authors.forename: Vítezslav
authors.initials: V
authors.lastname: Kríz
authors.forename: Vendula
authors.initials: V
authors.lastname: Pospíchalová
authors.forename: Jan
authors.initials: J
authors.lastname: Masek
authors.forename: Michaela Brita Christina
authors.initials: MB
authors.lastname: Kilander
authors.forename: Josef
authors.initials: J
authors.lastname: Slavík
authors.forename: Kristina
authors.initials: K
authors.lastname: Tanneberger
authors.forename: Gunnar
authors.initials: G
authors.lastname: Schulte
authors.forename: Miroslav
authors.initials: M
authors.lastname: Machala
authors.forename: Alois
authors.initials: A
authors.lastname: Kozubík
authors.forename: Juergen
authors.initials: J
authors.lastname: Behrens
authors.forename: Vítezslav
authors.initials: V
authors.lastname: Bryja
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D000072261:Dishevelled Proteins; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D060488:Low Density Lipoprotein Receptor-Related Protein-6 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D015778:Minor Histocompatibility Antigens; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D034622:RNA Interference; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D060509:Wnt3A Protein / Q000235:genetics / Q000378:metabolism*; D000071557:beta-Arrestins
chemical_list: C517118:AMER1 protein, human; D048868:Adaptor Proteins, Signal Transducing; D019390:Arrestins; D000072261:Dishevelled Proteins; C555475:LRP6 protein, human; D060488:Low Density Lipoprotein Receptor-Related Protein-6; D015778:Minor Histocompatibility Antigens; D019269:Phosphatidylinositol 4,5-Diphosphate; D010750:Phosphoproteins; D025521:Tumor Suppressor Proteins; D060509:Wnt3A Protein; D000071557:beta-Arrestins; D017853:Phosphotransferases (Alcohol Group Acceptor); C402182:phosphatidylinositol phosphate 4-kinase; C020077:1-phosphatidylinositol-4-phosphate 5-kinase
keywords: Amer1/WTX/FAM123B; Dvl; Lrp6 Phosphorylation; Membrane Lipids; Phosphatidylinositol Kinase; Phosphatidylinositol Phosphate Kinase; Phosphatidylinositol Signaling; Wnt Signaling; β-Arrestin; β-Catenin