The Effects And Molecular Mechanisms Of Advanced Glycation End-Products Acting On Diabetic Cataract

PartⅠAdvanced glycation end-products and TGF-βwith diabetic cataractPurpose To investigate the effects of advanced glycation end-products (AGEs) and TGF-βon the diabetic cataract.These data should provide molecular basis for further studying the pathogenesis of clinical diabetic cataract.Methods Aqueous and anterior capsule lens epithelial cells from the diabetic cataract and age-related cataract patients were extracted to detect the blood glucose,AGEs,and TGF-β2 using biochemical methods and enzyme-linked immunosorbent assay(Elisa).For the anterior capsule lens epithelial cells,dot blot was used to detect the protein expression of AGEs and TGF-β2,and real-time PCR was used to quantitatively detect the mRNA expressions of AGE receptor(RAGE),TGF-β1,TGF-β2,and TGF-β3.Results Blood glucose and AGEs of the aqueous significantly increased in the diabetic cataract compared to the age-related cataract(p＜0.01). RAGE mRNA expression of anterior capsule lens epithelial cells in the diabetic cataract were much higher than that of in the age-related cataract.TGF-βmRNA expression Either TGF-β2 in aqueous and lens epithelial cells or TGF-β2 mRNA expression in the lens epithelial cells of diabetic cataract obviously decreased compared to age-related cataract. In contrast with TGF-β2,TGF-β1 mRNA in the lens epithelial cells of diabetic cataract obviously increased in comparison with age-related cataract(p＜0.01).TGF-β3 mRNA expression in the age-related cataract was slightly higher than that in the diabetic cataract.Conclusion AGEs,RAGE,and TGF-β1 expression increased in the lens epithelial cells of diabetic cataract in comparison with age-related cataract.However,TGF-β2 in the aqueous and lens epithelial cells of diabetic cataract obviously decreased.These results indicated that AGEs and TGF-βwere related with the pathogenesis of diabetic cataract. PartⅡMolecular mechanisms of advanced glycation end-products on lens epithelial cellsPurpose To investigate the effects of advanced glycation end-products on the proliferation and cell cycle of lens epithelial cells,p21,p27 and c-myc protein expressions of lens epithelial cells both in diabetic and age-related cataract were studied as well.Methods The effect of AGEs on the proliferation of lens epithelial cells was detected by MTT methods,and cell cycle was analyzed by flow cytometry. FN,α-SMA and collagenⅠexpressions of cultured lens epithelial cells after adding AGEs by using immunofluorescence.Cell signal molecular expressions of MAPK and ERK in cultured lens epithelial cells with or without AGEs and p21,p27,c-myc protein in anterior capsule lens epithelial cells were determined by western blot.Results Lower concentration of AGEs inhibited the proliferation of lens epithelial cells,even made cell apoptosis.Higher concentration of AGEs accelerated cell proliferation and the effect was most obviously at 48hrs after adding AGEs.Aminoguanidine inhibited the proliferative effect of AGEs and cell cycle was blocked in G1 phase,p21 and p27 protein expression decreased and c-myc increased in diabetic cataract compared to age-related cataract.Expression of FN,α-SMA,TGF-βand collagenⅠof cultured lens epithelial cells increased after adding AGEs.Cell signal moleculars MAKP and ERK expression also increased in the action of AGEs. Conclusion:The proliferation of lens epithelial cells in diabetic cataract was more active compared to age-related cataract.Higher concentration of AGEs promoted the proliferation of lens epithelial cells, and aminoguanidine inhibited this effect by blocking G1 phase of cell cycle.Expression of FN,α-SMA,TGF-βand collagenⅠof cultured lens epithelial cells increased after the action of AGEs.This effects induced from AGEs might be correlated to the MAPK signal transduction pathway.