We propose to examine the mechanisms of retinal degeneration associated with specific mutations in the human rhodopsin gene: the first in codon 23, a substitution of histidine for proline at position 23 of rhodopsin (P23H) and the second in codon 347, a substitution of serine for proline at position 347 (P347S). These two forms of the mutant human rhodopsin gene have been used to generate separate lines of transgenic mice. All five of the P23H and P347S transgenic lines represent models for human autosomal dominant retinitis pigmentosa because the transgenic retinas express mutant opsin protein and undergo photoreceptor degeneration with reduced and delayed ERGs. The studies proposed here are designed to define the mechanisms of photoreceptor loss in both the P23H and P347S transgenic retinas. Specifically, we will: 1) determine the intracellular fate of the mutant rhodopsins, 2) define the properties of P23H and P347S rhodopsin expressed within a transgenic retina, 3) quantitate the amounts of transgenic opsin present within the photoreceptors across the timespan of the degeneration, 4) define the developmental time course of mutant opsin expression, 5) determine the rate of outer segment disk addition in the transgenic retinas, and 6) evaluate the levels of specific nucleotides, particularly cyclic guanosine monophosphate, over the time course of degeneration. Potential treatments that might improve or prolong photoreceptor survival in the transgenic retinas will be tested using a recently developed co-culture system. Photoreceptor survival will be measured in transgenic retinas co-cultured with retinal pigment epithelial cells in the presence or absence of factors that might modify the effects of specific defects in rhodopsin. Definition of pathogenetic mechanisms and studies in the transgenic co-culture system may provide rational bases for designing treatments applicable to human patients with rhodopsin mutations.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY010098-02
Application #
2163794
Study Section
Visual Sciences C Study Section (VISC)
Project Start
1993-04-01
Project End
1998-03-31
Budget Start
1994-04-01
Budget End
1995-03-31
Support Year
2
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Harvard University
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
082359691
City
Boston
State
MA
Country
United States
Zip Code
02115
Roof, D J; Adamian, M; Hayes, A (1994) Rhodopsin accumulation at abnormal sites in retinas of mice with a human P23H rhodopsin transgene. Invest Ophthalmol Vis Sci 35:4049-62