title: Photoreceptors in whirler mice show defective transducin translocation and are susceptible to short-term light/dark changes-induced degeneration.
abstract: Usher syndrome combines congenital hearing loss and retinitis pigmentosa (RP). Mutations in the whirlin gene (DFNB31/WHRN) cause a subtype of Usher syndrome (USH2D). Whirler mice have a defective whirlin gene. They have inner ear defects but usually do not develop retinal degeneration. Here we report that, in whirler mouse photoreceptors, the light-activated rod transducin translocation is delayed and its activation threshold is shifted to a higher level. Rhodopsin mis-localization is observed in rod inner segments. Continuous moderate light exposure can induce significant rod photoreceptor degeneration. Whirler mice reared under a 1500 lux light/dark cycle also develop severe photoreceptor degeneration. Previously, we have reported that shaker1 mice, a USH1B model, show moderate light-induced photoreceptor degeneration with delayed transducin translocation. Here, we further show that, in both whirler and shaker1 mice, short-term moderate light/dark changes can induce rod degeneration as severe as that induced by continuous light exposure. The results from shaker1 and whirler mice suggest that defective transducin translocation may be functionally related to light-induced degeneration, and these two symptoms may be caused by defects in Usher protein function in rods. Furthermore, these results indicate that both Usher syndrome mouse models possess a light-induced retinal phenotype and may share a closely related pathobiological mechanism.
authors.affiliation: Sensory Neuroscience Department, Boys Town National Research Hospital, 555 North 30th St., Omaha, NE 68131, USA; National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Tian
authors.affiliation: Sensory Neuroscience Department, Boys Town National Research Hospital, 555 North 30th St., Omaha, NE 68131, USA.
authors.forename: Weimin
authors.initials: W
authors.lastname: Wang
authors.affiliation: Sensory Neuroscience Department, Boys Town National Research Hospital, 555 North 30th St., Omaha, NE 68131, USA.
authors.forename: Duane
authors.initials: D
authors.lastname: Delimont
authors.affiliation: Sensory Neuroscience Department, Boys Town National Research Hospital, 555 North 30th St., Omaha, NE 68131, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Cheung
authors.affiliation: Sensory Neuroscience Department, Boys Town National Research Hospital, 555 North 30th St., Omaha, NE 68131, USA.
authors.forename: Marisa
authors.initials: M
authors.lastname: Zallocchi
authors.affiliation: Sensory Neuroscience Department, Boys Town National Research Hospital, 555 North 30th St., Omaha, NE 68131, USA; University of Nebraska Medical Center, 600 S 42nd, Omaha, NE 68198, USA.
authors.forename: Dominic
authors.initials: D
authors.lastname: Cosgrove
authors.affiliation: Sensory Neuroscience Department, Boys Town National Research Hospital, 555 North 30th St., Omaha, NE 68131, USA. Electronic address: You-Wei.Peng@boystown.org.
authors.forename: You-Wei
authors.initials: YW
authors.lastname: Peng
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D002452:Cell Count; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D017440:Photoperiod; D012162:Retinal Degeneration / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D015293:Transducin / Q000235:genetics* / Q000378:metabolism; D014178:Translocation, Genetic
chemical_list: D015293:Transducin
keywords: Usher syndrome; light-induced degeneration; photoreceptor degeneration; retinitis pigmentosa; shaker1; transducin; whirler