title: Smoothened determines β-arrestin-mediated removal of the G protein-coupled receptor Gpr161 from the primary cilium.
abstract: Dynamic changes in membrane protein composition of the primary cilium are central to development and homeostasis, but we know little about mechanisms regulating membrane protein flux. Stimulation of the sonic hedgehog (Shh) pathway in vertebrates results in accumulation and activation of the effector Smoothened within cilia and concomitant disappearance of a negative regulator, the orphan G protein-coupled receptor (GPCR), Gpr161. Here, we describe a two-step process determining removal of Gpr161 from cilia. The first step involves β-arrestin recruitment by the signaling competent receptor, which is facilitated by the GPCR kinase Grk2. An essential factor here is the ciliary trafficking and activation of Smoothened, which by increasing Gpr161-β-arrestin binding promotes Gpr161 removal, both during resting conditions and upon Shh pathway activation. The second step involves clathrin-mediated endocytosis, which functions outside of the ciliary compartment in coordinating Gpr161 removal. Mechanisms determining dynamic compartmentalization of Gpr161 in cilia define a new paradigm for down-regulation of GPCRs during developmental signaling from a specialized subcellular compartment.
authors.affiliation: Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Kasturi
authors.initials: K
authors.lastname: Pal
authors.affiliation: Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Sun-Hee
authors.initials: SH
authors.lastname: Hwang
authors.affiliation: Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Bandarigoda
authors.initials: B
authors.lastname: Somatilaka
authors.affiliation: Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Hemant
authors.initials: H
authors.lastname: Badgandi
authors.affiliation: Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Jackson
authors.affiliation: Division of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521.
authors.forename: Kathryn
authors.initials: K
authors.lastname: DeFea
authors.affiliation: Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390 saikat.mukhopadhyay@utsouthwestern.edu.
authors.forename: Saikat
authors.initials: S
authors.lastname: Mukhopadhyay
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D015374:Biosensing Techniques; D002923:Cilia / Q000378:metabolism; D015536:Down-Regulation; D004705:Endocytosis; D005347:Fibroblasts / Q000378:metabolism*; D054769:G-Protein-Coupled Receptor Kinase 2 / Q000378:metabolism; D057809:HEK293 Cells; D053823:Hedgehog Proteins / Q000378:metabolism; D006801:Humans; D051379:Mice; D009154:Mutation; D041681:NIH 3T3 Cells; D011485:Protein Binding; D021381:Protein Transport; D034622:RNA Interference; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D000072086:Smoothened Receptor; D013997:Time Factors; D014162:Transfection; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; C000588604:GPR161 protein, human; C533095:GPR161 protein, mouse; D053823:Hedgehog Proteins; D043562:Receptors, G-Protein-Coupled; C509239:SHH protein, human; C491023:SMO protein, human; C465570:Shh protein, mouse; C491022:Smo protein, mouse; D000072086:Smoothened Receptor; D000071557:beta-Arrestins; C496567:GRK2 protein, human; C496568:GRK2 protein, mouse; D054769:G-Protein-Coupled Receptor Kinase 2