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Bhagwat V Alapure, Katelyn N Robillard, Jennifer J Lentz; Antisense oligonucleotides rescue light-induced translocation of α-transducin & arrestin in Usher photoreceptors. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3989.
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© ARVO (1962-2015); The Authors (2016-present)
Photoreceptors (PRs) undergo several adaptations in response to light. In the dark, α-transducin resides in rod outer segments (OS) and arrestin in inner segments (IS). In the presence of light, α-transducin moves from OS to IS and the cell body; whereas arrestin moves from IS to OS. The connecting cilia (CC) plays an important role in transport the phototransduction proteins. Harmonin, a scaffolding protein encoded by the USH1C gene, is expressed in cochlear hair cells and photoreceptors. In the ear, harmonin plays an important role in hair cell development and function through interactions with other proteins and the stereocilia. The function of harmonin in the retina is not known. Mutations in harmonin cause Usher syndrome (Usher), the leading genetic cause of concurrent hearing and vision loss. Mice that contain the USH1C c.216G>A mutation responsible for Type 1 Usher in the Acadian population in Louisiana, USA and Canada, are deaf, and have vestibular and visual dysfunction similar to patients. The PRs in Usher mice also have reduced light-activated movement of phototransduction proteins, α-transducin and arrestin. We hypothesize that antisense oligonucleotide (ASO) treatment, which restore a visual function in the Usher mice, rescues the delayed translocation of phototransduction proteins in PRs.
Dark adapted USH1C c.216G>A knock-in (Usher), ASOs-treated Usher (ASO-Usher), and wild-type littermate control (WT) adult mice were exposed to various levels of bright light. Localization of α-transducin and arrestin in the retina was measured in dark and light adapted retinas using western blot and immunohistochemistry (IHC) techniques.
Western blot analyses showed no difference in the level of α-transducin and arrestin in the retinas of Usher, ASO-treated and WT mice. However, IHC analyses showed reduced levels of arrestin and increased levels of α-transducin in the OS, IS and ONL subcellular compartments of PRs of 2 and 3 month old Usher mice exposed to bright light. ASO treatment of Usher mice by intravitreal injection at postnatal day 21 restored arrestin and α-transducin to WT levels in OS, IS and ONL subcellular compartments of PRs.
These data demonstrate that ASO treatment rescues the light induced translocation of arrestin and α-transducin in Usher PRs and suggest a new role for harmonin in the retina.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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