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David W Li, Yunfei Liu, Jia-Wen Xiang, xiaodong Gong, Fangyuan Liu, Jia-Ling Fu, Yuan Xiao, Ling Wang, Yizhi Liu; Sumoylation Regulation of Lens Cataractogenesis. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1130.
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© ARVO (1962-2015); The Authors (2016-present)
Our recent studies revealed that sumoylation is necessary to activate the p32 Pax6, the shortest isoform of Pax6, the master regulator for eye and brain development (Yan et al. 2010. PNAS). Moreover, our studies further revealed that sumoylation plays an important role in regulating lens differentiation (Qong et al. 2014. PNAS). Here we demonstrate that sumoylation has important functions in regulating cataractogenesis.
SUMO1(-/-) knockout mice and vimentin E151K mice were established with CRISPR-CAS9 technology. Adult mouse lenses from wild type and SUMO1 knockout mice were irradiated with UVA followed by culturing at media 199. RNAseq, QRT-PCR, Western blot analysis and immunocytochemistry were used to analyze gene expression. CellTitle-Glo assay, Hoechst staining and cell flow cytometry were used for apoptosis analysis.
After UVA irradiation, SUMO1(-/-) lenses develop cataract in 2-4 hours during the post-irradiation culture, while the wild type lenses remain transparent for up to 10 hours. After 10 hours post UVA irradiation, the wild type mouse lens also began to develop cataract. At the molecular level, caspase-3 in the SUMO1(-/-) lens was completely activated after 2-hour culture post-UVA irradiation while in the wild type lens majority of the caspase-3 exists in pro-caspase-3 and partially processed caspase-3. Co-IP linked Western blot analysis revealed that caspase-3 was sumoylated in the wild type animal but not in the SUMO1 (-/-) mouse lenses. UVA irradiation also significantly activates p53, and upregulates caspase-8 but down regulates Bcl-2 in the SUMO1(-/-) lens in comparison with wild type lenses. In addition, creation of a novel sumoylation site in vimentin (the E151K mutant) causes cataract through blockage of oligomerization of the vimentin monomers.
SUMO1 regulates both extrinsic and intrinsic apoptotic pathways through controlled caspase-3 activation. Under stress condition, lack of SUMO1 greatly promotes activation of Caspase-3, and both the extrinsic and intrinsic apoptotic pathways. Sumoylation of the E151K mutant vimentin blocks normal polymerization, causing cataractogenesis (Supported by grants from National Natural Science Foundation of China, 81570824, 81770910, 81500738, 81500707, and 81700821 as well as the Fundamental Funds from the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University).
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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