title: Light-dependent translocation of arrestin in rod photoreceptors is signaled through a phospholipase C cascade and requires ATP.
abstract: Partitioning of cellular components is a critical mechanism by which cells can regulate their activity. In rod photoreceptors, light induces a large-scale translocation of arrestin from the inner segments to the outer segments. The purpose of this project is to elucidate the signaling pathway necessary to initiate arrestin translocation to the outer segments and the mechanism for arrestin translocation. Mouse retinal organotypic cultures and eyes from transgenic Xenopus tadpoles expressing a fusion of GFP and rod arrestin were treated with both activators and inhibitors of proteins in the phosphoinositide pathway. Confocal microscopy was used to image the effects of the pharmacological agents on arrestin translocation in rod photoreceptors. Retinas were also depleted of ATP using potassium cyanide to assess the requirement for ATP in arrestin translocation. In this study, we demonstrate that components of the G-protein-linked phospholipase C (PLC) pathway play a role in initiating arrestin translocation. Our results show that arrestin translocation can be stimulated by activators of PLC and protein kinase C (PKC), and by cholera toxin in the absence of light. Arrestin translocation to the outer segments is significantly reduced by inhibitors of PLC and PKC. Importantly, we find that treatment with potassium cyanide inhibits arrestin translocation in response to light. Collectively, our results suggest that arrestin translocation is initiated by a G-protein-coupled cascade through PLC and PKC signaling. Furthermore, our results demonstrate that at least the initiation of arrestin translocation requires energy input.
authors.affiliation: Department of Ophthalmology, University of Florida, Gainesville, Florida 32610-0284, USA.
authors.forename: Wilda
authors.initials: W
authors.lastname: Orisme
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Tobias
authors.initials: T
authors.lastname: Goldmann
authors.forename: Susan
authors.initials: S
authors.lastname: Bolch
authors.forename: Uwe
authors.initials: U
authors.lastname: Wolfrum
authors.forename: W Clay
authors.initials: WC
authors.lastname: Smith
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D019393:Arrestin / Q000378:metabolism*; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008027:Light; D051379:Mice; D010716:Phosphatidylinositols / Q000378:metabolism; D011190:Potassium Cyanide / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D017948:Retinal Rod Photoreceptor Cells / Q000378:metabolism*; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D014982:Xenopus laevis / Q000378:metabolism
chemical_list: D019393:Arrestin; D004791:Enzyme Inhibitors; D010716:Phosphatidylinositols; D000255:Adenosine Triphosphate; D002772:Cholera Toxin; D011493:Protein Kinase C; D010738:Type C Phospholipases; D011190:Potassium Cyanide