Purchase this article with an account.
M.H. Elliott, M. Tanito, M.E. McClellan, D.G. Birch; Caveolin–1 Null Mice Have Reduced Retinal Function Without Overt Retinal Degeneration . Invest. Ophthalmol. Vis. Sci. 2006;47(13):820.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Caveolin–1 (Cav–1) is an important lipid raft–associated protein expressed in several retinal cell–types that may regulate photoreceptor function. Cav–1 can interact with the alpha subunit of transducin and cofractionates with significant pools of other phototransduction proteins in detergent–resistant membranes isolated from rod outer segments (ROS). The in vivo functional significance of these interactions is unknown, so we set out to characterize the retinal phenotype of Cav–1 null mice.
Cav–1 null and isogenic control mice (2 months of age) were dark–adapted overnight, anesthetized, and pupils were dilated. Five white light stimuli (10 msec each) of increasing flash energies were presented and ERG responses were recorded. We analyzed a– and b–wave amplitudes and fit the a–waves (representing primarily rod responses) to a computational model of phototransduction to determine sensitivity (S), a parameter reflecting phototransduction gain. Following ERG recording, eyes were removed and processed for qualitative morphology and quantitative morphometry (i.e., retinal thickness measurements). In separate experiments, rhodopsin content was measured spectrophotometrically and rhodopsin localization by immunocytochemistry. Photoreceptor ROS were also prepared and examined by SDS–polyacrylamide gel electrophoresis. ERG response amplitudes and quantitative morphometry were also assessed on 8–month old mice.
At 2 months of age, Cav–1 null mice had significantly reduced a– and b–wave amplitudes compared to controls. In addition, preliminary analysis of a–wave responses indicated a significant decrease in S. This decrease was not due to gross retinal degeneration as outer nuclear layer thickness of Cav–1 null mice was not significantly different from controls. There was no significant difference in rhodopsin content, and rhodopsin appeared to be localized normally in Cav–1 null mice. Furthermore, the protein profile of ROS membranes isolated from Cav–1 null mice was indistinguishable from controls. Histology and ERG results from 8–month old Cav–1 nulls were not different from 2–month old mice.
Cav–1 null mice have reduced retinal function that is not accompanied by gross retinal degeneration (at the ages examined). These results suggest that Cav–1 modulates photoreceptor signaling by a mechanism not yet determined.
This PDF is available to Subscribers Only