AlphaA-Crystallin Suppresses DBC1, A Negative Regulator of SIRT1 to Repress Stress-Induced Apoptosis of Lens Epithelial Cells

Abstract

Purpose : Alpha-crystallins are important apoptotic regulators, we have previously demonstrated that alpha-crystallin regulates multiple targets to suppress stress-induced apoptosis, and subsequently cataractogenesis (Mao et al. 2004. Cell Death & Differentiation. 11(5):512-26; Li et al., 2005. Mol Biol Cell. 16(9):4437-53.). Here, we demonstrated that AlphaA-crystallin regulates a novel target, DBC1, a negative regulator of SIRT1 (Kim et al. 2008. Nature. 451(7178):583-586) .

Methods : Normal mouse eyeballs at different developmental stages (from ED 10.5 to ED 19.5) were harvested for immunofluorescence, RT-RCP and Western blot analysis of DBC1. The cell viability and apoptosis detection kits were used to detect the level of apoptosis under different conditions.

Results : At the mRNA and the protein levels, expression of DBC1 can be detected at different stages of mouse eye development. The level of DBC1 was high in the early stage of lens vesicle and gradually decrease during lens fiber differentiation. Silence of alphaA-crystallin significantly upregulates the expression level of DBC1. Furthermore, we demonstrated that in the ocular lens, SUMOylation of DBC1 was mediated by SUMO1. Modification of DBC1 by SUMO1 at K591 promotes the interaction between DBC1 and p53. As a result, oxidative stress-induced apoptosis of lens epithelial cells was greatly enhanced.

Conclusions : AlphaA-crystallin suppresses stress-induced apoptosis of lens epithelial cells through repression of the DBC1-p53 signaling pathway. During lens development, DBC1-p53 pathway-mediated apoptosis helps to craft the developing lens. [Supported by National Natural Science Foundation of China (Grants ^#82271071, ^#81970787, & ^#81770910) and the Joint Key Project from the Natural Science Foundation of Guangdong Province and Guangzhou City (2019B1515120014)，and the Fundamental Funds of the State Key Laboratory of Ophthalmology of Zhongshan Ophthalmic Center (3030901010111)].

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.