Journal
INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE
Volume 47, Issue 5, Pages 2150-2160Publisher
ASSOC RESEARCH VISION OPHTHALMOLOGY INC
DOI: 10.1167/iovs.05-0919
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- NEI NIH HHS [R01 EY013533, R01 EY003575, EY03575, R01 EY013533-05, EY013533] Funding Source: Medline
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PURPOSE. Peripherin/rds and rom-1 have structural roles in morphogenesis and stabilization of the outer segment, but little is known about their transport and sorting to the rod outer segment. Peripherin/rds and rom-1 trafficking were studied in several knockout and transgenic animal models. METHODS. Rod outer segment formation and distribution of peripherin/rds and rom-1 were examined by immunohistochemistry, electron microscopy, and molecular biological methods in wild-type, rhodopsin-knockout, and peripherin/rds-knockout mice. C-terminally truncated peripherin/rds (Xper38)-GFP chimeric protein sorting was followed by immunofluorescence microscopy in transgenic Xenopus. RESULTS. In developing wild-type photoreceptors, peripherin/rds was detected exclusively in the distal tip of the connecting cilium in advance of outer segment formation. Rhodopsin-knockout mice failed to create normal rod outer segments and instead, elaborated membranous protrusions at the distal cilium tip. Peripherin/rds and rom-1 localized to this ciliary membrane in rhodopsinless photoreceptors. In transgenic Xenopus, a C-terminally truncated peripherin/rds-GFP fusion predominantly localized to its normal location within disc rims. In developing rds mice, rom-1 accumulated primarily in distal ciliary membranes. CONCLUSIONS. Peripherin/rds transport and localization are polarized to the site of outer segment morphogenesis before disc formation in developing photoreceptors. Peripherin/rds and rom-1 trafficking is maintained in rhodopsin-knockouts, suggesting that rim proteins and rhodopsin have separate transport pathways. The presence of truncated peripherin/rds-GFP in the outer segment supports previous evidence that peripherin/rds mice form homotetramers for outer segment targeting. The finding that rom-1 transports to the outer segment domain in rds mice suggests that rom-1 may possess its own sorting and transport signals.
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