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ES Lee, BB Burnside, JG Flannery; Expression Of A C-terminal Truncated Rhodopsin On A Rhodopsin Null Background . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2691.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Previous studies in transgenic animals have shown that mutant opsin (s334ter) harboring a 15 aa C-terminal truncation is found in the outer segment even though the majority of these truncated opsins mis-sort to other photoreceptor membranes. This investigation continues studies of the transport mechanism of normal and truncated mutant rhodopsin in rod photoreceptors. Methods: CTA9 mice expressing s334 mutant rhodopsin were crossed to rhodopsin null mice to generate animals on different knockout backgrounds. Eyes from mice of genotype (s334 +/-,rho -/-) and (s334 +/-, rho +/-) were processed at P7-10 for histology and immunocytochemistry to examine outer segment formation and rhodopsin distribution. Littermate and age-matched animals (rho +/+, rho +/-, rho -/-) were used as controls. Opsin levels were quantified by RT-PCR and Western Blotting. Results: Mice expressing C-terminal truncated rhodopsin s334ter in the absence of wildtype rhodopsin failed to form outer segments at postnatal day eight (P8), although mutant opsin was detected in the distal tip of the connecting cilium. Restoration of one copy of full-length wildtype rhodopsin in s334 +/-, rho +/- animals was sufficient to restore membrane accumulation and outer segment disk formation, albeit to a lower level compared to rho +/- controls. Conclusion: These data argue against a model of photoreceptor disk morphogenesis in which a bulk-flow mechanism soley governs rhodopsin transport to the outer segment during development.
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