"Super p53" mice display retinal astroglial changes
Juan J Salazar1, Roberto Gallego-Pinazo, Rosa de Hoz
1Instituto de Investigaciones Oftalmológicas "Ramón Castroviejo", Universidad Complutense de Madrid, Madrid, Spain.
Abstract:
Tumour-suppressor genes, such as the p53 gene, produce proteins that inhibit cell division under adverse conditions, as in the case of DNA damage, radiation, hypoxia, or oxidative stress (OS). The p53 gene can arrest proliferation and trigger death by apoptosis subsequent to several factors. In astrocytes, p53 promotes cell-cycle arrest and is involved in oxidative stress-mediated astrocyte cell death. Increasingly, astrocytic p53 is proving fundamental in orchestrating neurodegenerative disease pathogenesis. In terms of ocular disease, p53 may play a role in hypoxia due to ischaemia and may be involved in the retinal response to oxidative stress (OS). We studied the influence of the p53 gene in the structural and quantitative characteristics of astrocytes in the retina. Adult mice of the C57BL/6 strain (12 months old) were distributed into two groups: 1) mice with two extra copies of p53 ("super p53"; n = 6) and 2) wild-type p53 age-matched control, as the control group (WT; n = 6). Retinas from each group were immunohistochemically processed to locate the glial fibrillary acidic protein (GFAP). GFAP+ astrocytes were manually counted and the mean area occupied for one astrocyte was quantified. Retinal-astrocyte distribution followed established patterns; however, morphological changes were seen through the retinas in relation to p53 availability. The mean GFAP+ area occupied by one astrocyte in "super p53" eyes was significantly higher (p<0.05; Student's t-test) than in the WT. In addition, astroglial density was significantly higher in the "super p53" retinas than in the WT ones, both in the whole-retina (p<0,01 Student's t-test) and in the intermediate and peripheral concentric areas of the retina (p<0.05 Student's t-test). This fact might improve the resistance of the retinal cells against OS and its downstream signalling pathways.
Insights
Increased p53 gene copies in mice enhanced astrocyte size and density in the retina. This suggests a potential protective role for p53 against retinal oxidative stress.
Area of Science:
- Neuroscience
- Ophthalmology
- Genetics
Background:
- Tumor suppressor p53 protein regulates cell division in response to DNA damage, hypoxia, and oxidative stress (OS).
- Astrocytic p53 plays a role in neurodegenerative diseases and retinal responses to OS and hypoxia.
- The influence of p53 on retinal astrocyte structure and quantity requires further investigation.
Purpose of the Study:
- To investigate the impact of increased p53 gene copies on the structural and quantitative characteristics of retinal astrocytes.
- To assess potential alterations in astrocyte morphology and density in response to varying p53 levels.
Main Methods:
- Adult C57BL/6 mice were divided into two groups: "super p53" (two extra p53 copies) and wild-type (WT) controls.
- Retinal immunohistochemistry was performed to detect glial fibrillary acidic protein (GFAP)-expressing astrocytes.
- Manual counting and area quantification of GFAP+ astrocytes were conducted to assess density and size.
Main Results:
- Mice with "super p53" exhibited significantly larger mean GFAP+ astrocyte areas compared to WT controls (p<0.05).
- Astroglial density was significantly higher in "super p53" retinas than in WT retinas across the whole retina (p<0.01) and specific regions (p<0.05).
Conclusions:
- Elevated p53 levels alter retinal astrocyte morphology, increasing individual cell size and overall astroglial density.
- These structural changes in astrocytes may enhance retinal cell resistance to oxidative stress and its signaling pathways.
- Further research is warranted to elucidate the therapeutic potential of modulating p53 in ocular diseases.
