Abstract
Purpose :
Existence of multi-nucleated (MN)retinal pigment epithelial cells(RPE) has been demonstrated inboth human and mouse.In human, specific macular distribution ofMN RPE, and the positive correlation between MN RPE and rod photoreceptors has been reported, suggesting MN RPE reflect physiological functions. Because damaged DNA is detected in RPE from patients with age-related macular degeneration (AMD), here we analyzed the DNA damage response in mono-nucleated (MO) and MN RPE, and explored the regulatory effects of p53, the key DNA damage player, in this process.
Methods :
Immunofluorescence (IF) was performed to measure the percentage and distribution of MO and MN RPE cells in 2-month C57BL/6J mice (n=4). To induce DNA damage, 2-month wild-type (n=8) and p53+/- (n=8) mice were exposed to 1 GyX-ray irradiation.The DNA damage repair efficiencywas evaluated by comet assay and immunofluorescence with anti-γ H2Ax (DNA damage marker) at 1- or 3-day post irradiation.
Results :
MN RPE cells show higher distribution in the center region of retina (75.4%) as compared with peripheral retina (40.8%). Irradiation-induced DNA damage occurs in both MO and MN RPE cells.IF analysis shows more γH2Ax signals in MN as compared with MO RPE at both 1- (41.2% vs. 27.7%) and 3-day post irradiation (9.2% vs. 6.1%). Comet assay shows that the overall DNA double strand breaks were repaired with less efficiency in p53+/- RPEas compared with wild type mice at 3-day after irradiation, but the MO and MN RPE cells exhibited similar repair efficiency in both WT and p53+/- mice.
Conclusions :
MN RPE appears to repair DNA less efficiently than MO RPE cells upon X-ray irradiation, and p53 is required for DNA damage repair in both MO and MN RPE. (Supported by National Natural Science Foundation of China (#82070969, #81770910, #81970787) and the Fundamental Research Funds for the Central Universities (#19ykpy153)).
This is a 2021 ARVO Annual Meeting abstract.