Effects Of Sep15 Gene Silencing And Thapsigargin On Cadherin Expression In Human Lens Epithelial Cells

Cataract is one of the most common reasons that cause blindness and it is a great threat to human health. Selenium is one of essential trace elements, it functions in the form of selenoproteins. When the 15-kDa selenoprotein(Sep15) gene was knocked out, mice showed lens opacification as early as at 1.5 months after birth, which indicated that Sep15 was essential for the process of development of lens, but the precise mechanism that Sep15 regulated lens development was unclear. Investigating the relationship between Sep15 and Cataract for making use of selenium to prevent or delay cataracts has very important scientific significance and potential applications.As Cadherin(N-cadherin, CDH2) plays an integral role in the differentiation of lens cells, we used the immortalized human lens epithelial cells(h LECs) SRA01/04 cell lines as the research object in this study. By using the RNAi, RT-PCR, Western blotting and other methods, we explored effects of Sep15 gene silencing and thapsigargin(Tg) on the expression of lens' CDH2 to reveal the role of Sep15 in h LECs' differentiation. The main results are as follows:(1)The cytotoxicity that caused by Tg on h LECs was depended on its concentration. Apoptosis rate increased when the Tg concentration that treated on hLECs increased. At the concentration of 1?M, Tg could induce endoplasmic reticulum stress significantly and increased the mRNA and protein levels of GRP78 in hLECs. Low concentrations of Tg induced expression of Cadherin to increase, but had little effect on the level of Sep15, while high concentrations of Tg inhibited expressions of CDH2 and Sep15 obviously.(2)When hLECs were treated with bFGF, b FGF stimulated cell proliferation at low concentrations, while it promoted cell differentiation at high concentrations. When hLECs were treated with Tg and bFGF together, the addition of bFGF could decrease cytotoxicity caused by endoplasmic reticulum stress and relieved the effect of Tg on CDH2 expression, while Tg interfered the process of bFGF-mediated differentiation of hLECs.(3)Treating h LECs with Tg and bFGF, it had no significant effect on the gene silencing effect of Sep15. Inhibition of the Sep15 expression had no effect on the expression of GRP78 and could not cause significant changes in protein expression level of CDH2, which indicated that the formation of cataract that caused by Sep15 gene silencing had no direct relationship with endoplasmic reticulum stress signaling pathways and the cellular differentiation signaling molecule, CDH2. Sep15 gene silencing aggravated Tg-induced endoplasmic reticulum stress obviously and led to the expression of CDH2 increasing. The results showed that Sep15 had an important role in protecting hLECs from endoplasmic reticulum stress-induced disorder of CDH2 expression.