Fine mapping of chromosome 9 locus associated with congenital cataract

lncRNA TUG1 regulates Smac/DIABLO expression by competitively inhibiting miR-29b and modulates the apoptosis of lens epithelial cells in age-related cataracts

BACKGROUND

As one of the early discovered long non-coding RNAs (lncRNA), taurine upregulation gene 1 ( TUG1 ) has been widely expressed in a variety of tumors. Moreover, it promotes cell proliferation, differentiation, apoptosis, and migration. However, our understanding of its importance in the pathogenesis of cataracts remains limited. This study aimed to explore the mechanism by which lncRNA TUG1 mediates lens epithelial cell apoptosis in age-related cataracts (ARC) by regulating the microRNAs (miR-29b)/second mitochondria-derived activator of caspases axis, and to identify more non-surgical strategies for cataract treatment.

METHODS

The messenger RNA expression levels of TUG1 , miR-29b, and Smac were detected using quantitative real-time polymerase chain reaction in vivo and in vitro . The expression of the Smac protein was analyzed by Western blotting and immunofluorescence. Flow cytometry and cell counting kit-8 assays were used to detect the cell apoptosis and proliferation rates, respectively. The targeted regulatory relationship between lncRNA TUG1 , miR-29b, and Smac was verified by viral vector construction, co-transfection, nuclear and cytoplasmic separation, luciferase reporter assays, and RNA immunoprecipitation.

RESULTS

TUG1 and Smac were expressed at high levels in ARC and HLE-B3 cells treated with 200 μmol/L H 2 O 2 , whereas miR-29b expression was decreased. In vitro cell experiments confirmed that down-regulation of TUG1 could inhibit the apoptosis of lens epithelial cells. Mechanistically, Smac expression was negatively regulated by miR-29b. TUG1 competitively inhibited miR-29b expression and caused greater release of Smac. In addition, miR-29b partially reversed the effects of TUG1 on human lens epithelial cell line cells.

CONCLUSIONS

lncRNA TUG1 increases Smac expression and promotes apoptosis of lens epithelial cells in ARC by competitively inhibiting miR-29b. This mechanism is the cytological basis for ARC formation. Based on these results, the lncRNA TUG1/miR29b/Smac axis may be a new molecular pathway that regulates ARC development.

Long non-coding RNA ANRIL alleviates H2O2-induced injury by up-regulating microRNA-21 in human lens epithelial cells

The accurate role of ANRIL in cataract is poorly understood. We aimed to reveal the effects of ANRIL on H2O2-treated HLECs, SRA01/04, as well as the regulatory mechanisms. Oxidative stress model of HLECs was induced by H2O2. Cell injury was evaluated according to cell proliferation, apoptosis and DNA damage using CCK-8 assay/flow cytometry and TUNEL assays/γH2AX staining. Expressions of ANRIL and miR-21 in HLECs were determined by RT-qPCR. The effects of miR-21, miR-34a and miR-122-5p inhibition as well as AMPK and β-catenin on HLECs with ANRIL overexpression and H2O2 stimulation were analyzed. In vivo experiment was performed via RT-qPCR. H2O2 repressed proliferation and induced apoptosis or DNA damage in HLECs. Those alterations induced by H2O2 were attenuated by ANRIL overexpression. MiR-21 was positively regulated by ANRIL, and both of them were repressed in H2O2-induced HLECs and cataract patient tissues. Inhibition of miR-21 but not miR-34a or miR-122-5p reversed the effects of ANRIL on H2O2-treated HLECs. Phosphorylation of AMPK and expression of β-catenin were increased by ANRIL via regulating miR-21. AMPK and β-catenin affected beneficial function of ANRIL-miR-21 axis.Therefore, lncRNA ANRIL attenuated H2O2-induced cell injury in HELCs via up-regulating miR-21 via the activation of AMPK and β-catenin.