title: Light regulates the ciliary protein transport and outer segment disc renewal of mammalian photoreceptors.
abstract: The outer segment (OS) of the rod photoreceptor is a light-sensing cilium containing ~1,000 membrane-bound discs. Each day, discs constituting the distal tenth of the OS are shed, whereas nascent discs are formed at the base of the OS through the incorporation of molecules transported from the inner segment. The mechanisms regulating these processes remain elusive. Here, we show that rhodopsin preferentially enters the OS in the dark. Photoexcitation of post-Golgi rhodopsins retains them in the inner segment. Disc-rim protein peripherin2/rds enters the OS following a rhythm complementary to that of rhodopsin. Light-dark cycle-regulated protein trafficking serves as a mechanism to segregate rhodopsin-rich and peripherin2/rds-rich discs into alternating stacks, which are flanked by characteristic cytoplasmic pockets. This periodic cytostructure divides the OS into approximately ten fractions, each containing discs synthesized in a single day. This mechanism may explain how the rod photoreceptor balances the quantity of discs added and removed daily.
authors: Dyson Vision Research Institute, Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY 10065, USA.
authors: Ya-Chu
authors: YC
authors: Hsu
authors: Dyson Vision Research Institute, Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY 10065, USA.
authors: Jen-Zen
authors: JZ
authors: Chuang
authors: Dyson Vision Research Institute, Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY 10065, USA; Department of Cell and Developmental Biology, Weill Medical College of Cornell University, New York, NY 10065, USA. Electronic address: chsung@med.cornell.edu.
authors: Ching-Hwa
authors: CH
authors: Sung
mesh_terms: D000818:Animals; D002923:Cilia; D008027:Light; D051379:Mice; D008810:Mice, Inbred C57BL; D064531:Peripherins; D021381:Protein Transport / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D055211:Retinal Photoreceptor Cell Inner Segment / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000378:metabolism*; D012243:Rhodopsin / Q000096:biosynthesis / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000502:physiology*
chemical_list: D064531:Peripherins; C579003:Prph2 protein, rat; D012243:Rhodopsin