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Rod and cone degeneration in the rd mouse is p53 independent
1Vision Science Research Program, Cellular and Molecular Division, Toronto Western Research Institute, University Health Network, Toronto, Canada.
Purpose:
To determine whether p53 is required for the death of rod and cone photoreceptors in rd mice, a model of human retinitis pigmentosa, and/or for the natural degeneration of inner nuclear layer (INL) cells in the developing retina.
Methods:
Rod photoreceptor and INL apoptosis was assessed by TUNEL staining of mouse sagittal sections from post natal day (P) 10, 13, 15, 17, and 20 day p53+/+ and p53-/- rd retinas. Cone photoreceptor survival was measured by counting the total number of peanut agglutinin (PNA) positive cells in eighty four 0.25 mm x 0.25 mm bins in each eye, distributed equally across the four quadrants of whole mount retinas from 3 month old p53+/+ and p53-/- rd retinas.
Results:
Both the kinetics of rod and INL cell death as well as the survival of cones were essentially unaffected by the absence of p53.
Conclusions:
Despite established links with retinal apoptosis, p53 is not essential for rod or cone cell degeneration in the rd mouse or for the elimination of bipolar and Muller cells during late retinal development.
Insights
The tumor suppressor p53 (p53) is not essential for photoreceptor or inner nuclear layer cell death in rd mice, a model for retinitis pigmentosa. This study clarifies p53
Area of Science:
- Ophthalmology
- Genetics
- Cell Biology
Background:
- Retinitis pigmentosa (RP) is a group of inherited retinal diseases.
- Photoreceptor degeneration is a hallmark of RP.
- The role of p53 in retinal apoptosis is not fully understood.
Purpose of the Study:
- To investigate the necessity of p53 for photoreceptor (rod and cone) death in rd mice.
- To determine if p53 is required for inner nuclear layer (INL) cell degeneration in developing retinas.
Main Methods:
- Apoptosis was assessed using TUNEL staining in p53+/+ and p53-/- rd mouse retinas at various postnatal days.
- Cone photoreceptor survival was quantified by counting peanut agglutinin (PNA)-positive cells in whole mount retinas.
Main Results:
- The absence of p53 did not alter the rate of rod and INL cell death.
- Cone photoreceptor survival remained unaffected in p53 knockout rd mice.
Conclusions:
- p53 is not essential for the degeneration of rod or cone photoreceptors in the rd mouse model.
- p53 does not play a critical role in the elimination of INL cells during late retinal development.