How does ‘Y285 Stop Mutation’ affect photoreceptor development in the mouse?

The photoreceptors of our eye’s retina are directly responsible for normal vision. Each rod and cone photoreceptor contains a series of continuously regenerating photoreceptor disks. The photoreceptor disks themselves convert photons from the environment to cellular signals, enabling sight. If the photoreceptor disks are unable to form properly or regenerate, the result is retinal degeneration and vision loss. This Honors College/Liberal Studies thesis project asks whether a Peripherin-2/rds (P/rds) mutation, “Y285 STOP” causes photoreceptor and retinal abnormalities in the mouse, and if so, how. Normal P/rds is 347 amino acids long. In comparison, the mutated variant of P/rds, Y285 STOP, only has 285 amino acids, due to early protein termination. This mutation causes macular pattern dystrophy in humans. Our lab hypothesizes that mice that inherit this mutation this project that Y285 STOP, may have a negative impact on photoreceptor formation compared to normal P/rds. Using a mouse model, we will measure the thickness of the retina and evaluate whether or not the Y285 STOP mutation causes photoreceptor cell death and retinal degeneration. It is known that the mouse retina is fully developed at about three weeks of age. Previous studies have also demonstrated that a normal retina displays an outer nuclear layer that is about 12 photoreceptor nuclei thick. If the Y285 STOP retina also displays an outer nuclear layer with an identical thickness at three weeks of age, this will suggest that Y285 STOP may not have a significant effect on initial retinal development. In contrast, if the mutant retina shows a thinner outer nuclear layer (fewer photoreceptors) this will suggest that P/rds is important for photoreceptor development. Regardless of the specific outcome, this information will help us use the mouse as a model of late onset human disease.