A reduced OGG1 expression was correlated with hypermethylation of a CpG island of OGG1 in lens cortex of ARC. The role of epigenetic change in OGG1 gene in the susceptibility to oxidative stress induced cortical ARC is warranted to further study.

Purpose To explore the involvement of N 6 -methyladenosine (m 6 A) modification in circular RNAs (circRNAs) and relevant methyltransferases in the lesion of lens epithelium cells (LECs) under the circumstances of age-related cataract (ARC). Methods LECs were collected from normal subjects and patients with cortical type of ARC (ARCC). M 6 A-tagged circRNAs and circRNAs expression were analyzed by m 6 A-modified RNA immunoprecipitation sequencing (m 6 A-RIP-seq) and RNA sequencing (RNA-seq). Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were used to predict possible functions of the m 6 A-circRNAs. Expression of m 6 A-related methyltransferase and demethytransferase was measured by quantitative real-time polymerase chain reaction. Expression and location of AlkB homolog 5 RNA demethylase (ALKBH5), a key component of m 6 A demethytransferase, were determined by Western blot and immunostaining. Results All 4646 m 6 A peaks within circRNAs had different abundances, with 2472 enriched and 2174 subdued. The level of m 6 A abundance in total circRNAs was decreased in the LECs from ARCCs in comparison with the controls. We also found that the expression of highly m6A-tagged circRNAs was mostly decreased in comparison with non-m 6 A-tagged circRNAs. The bioinformatics analysis predicted the potential functions of m 6 A modified circRNAs and the relevant pathways that may be associated with m 6 A modified circRNAs. Among five major methyltransferases, ALKBH5 was significantly upregulated in LECs of ARCCs. Conclusions Our data provided novel evidence regarding the involvement of circRNAs m 6 A modifications in ARC. The altered expression of methyltransferases in lens tissue might selectively change the epigenetic profile of lens genome through regulating genes that host the circRNAs, thus enhance the susceptibility to ARC. The results might provide a new insight in the molecular target of ARC pathogenesis.

PURPOSE. Long noncoding RNAs (lncRNAs) are important in disease progression and cellular functions. This study aimed to conduct global lncRNA profiling and characterize the role of lncRNA 1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase delta 3-sence RNA 1 (PLCD3-OT1) in the progression of age-related cataract (ARC). METHODS. We performed lncRNA expression profiling of lens capsule from ARC groups and age-matched groups using high-throughput RNA-sequencing. Real-time PCR was conducted to detect the expression pattern of lncRNA and mRNA in the clinical samples and cell model. Assays of cell-counting kit-8, 5 0-ethynyl-2 0-deoxyuridine, TUNEL, and propidium iodide staining were used to detect cell viability, proliferation, apoptosis, and cell cycle. We also performed fluorescence in situ hybridization assay to detect the location of lncRNA, and verified the endogenous competitive RNA mechanism between miRNAs, lncRNAs, and target genes via double-luciferase reporter analyses. RESULTS. The expression of lncRNA PLCD3-OT1 and PLCD3 were significantly decreased in ARC. PLCD3-OT1 overexpression promoted the expression of PLCD3, cell viability, proliferation, and inhibited cell apoptosis upon oxidative stress, while knockdown of PLCD3 showed the opposite results. Mechanistically, PLCD3-OT1functions through positively regulation the expression of PLCD3. In addition, PLCD3-OT1 may act as a ceRNA to regulate the expression of PLCD3 through competition for miR-224-5p. CONCLUSIONS. PLCD3-OT1 and PLCD3 may become potential therapeutic targets for the prognosis, diagnosis, and treatment of ARC.

Age‐related cataract (ARC) is caused by the exposure of the lens to UVB which promotes oxidative damage and cell death. This study aimed to explore the role of lncRNA H19 in oxidative damage repair in early ARC. lncRNAs sequencing technique was used to identify different lncRNAs in the lens of early ARC patients. Human lens epithelial cells (HLECs) were exposed to ultraviolet irradiation; and 8‐OHdG ELISA, Cell counting kit 8 (CCK8), EDU, flow cytometry and TUNEL assays were used to detect DNA damage, cell viability, proliferation and apoptosis. Luciferase assay was used to examine the interaction among H19, miR‐29a and thymine DNA glycosylase (TDG) 3'UTR. We found that lncRNA H19 and TDG were highly expressed while miR‐29a was down‐regulated in the three types of early ARC and HLECs exposed to ultraviolet irradiation, compared to respective controls. lncRNA H19 knockdown aggravated oxidative damage, reduced cell viability and proliferation, and promoted apoptosis in HLECs, while lncRNA H19 overexpression led to opposite effects in HLECs. Mechanistically, miR‐29a bound TDG 3'UTR to repress TDG expression. lncRNA H19 up‐regulated the expression of TDG by repressing miR‐29a because it acted as ceRNA through sponging miR‐29a. In conclusion, the interaction among lncRNA H19, miR‐29a and TDG is involved in early ARC. lncRNA H19 could be a useful marker of early ARC and oxidative damage repair pathway of lncRNA H19/miR‐29a/TDG may be a promising target for the treatment of ARC.

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