腺病毒过表达TXNIP抑制INS-1胰岛β细胞增殖

Adenovirus-mediated overexpression of thioredoxin interaction protein inhibits INS-1 islet β cell proliferation

糖尿病可以引起硫氧还蛋白相互作用蛋白(thioredoxin interaction protein,TXNIP)表达增加,而TXNIP可以结合内源性硫氧还蛋白(thioredoxin,Trx)并抑制其活性。本研究旨在探讨TXNIP对INS-1胰岛β细胞增殖的影响及机制。构建TXNIP过表达(Ad-TXNIP-GFP)和半胱氨酸247位点突变的TXNIP过表达(Ad-TXNIPc247s-GFP)腺病毒载体并感染INS-1细胞,用Ed U法和Ki67法检测细胞增殖,用Western blot检测ERK和AKT蛋白磷酸化水平。结果显示,TXNIP和TXNIPc247s(不能与Trx特异性结合并抑制其活性)蛋白过表达均显著抑制INS-1细胞增殖,且TXNIP过表达细胞增殖的受抑制程度大于TXNIPc247s过表达细胞。另外,TXNIP和TXNIPc247s过表达均抑制INS-1细胞ERK和AKT的磷酸化。以上结果提示,TXNIP过表达可能通过Trx依赖途径以及非Trx依赖途径抑制ERK和AKT的磷酸化,进而抑制INS-1细胞增殖。

Diabetes can cause a significant increase in the expression of thioredoxin（Trx）-interacting protein（TXNIP）, which binds to Trx and inhibits its activity. The present study was aimed to investigate the effect of TXNIP on proliferation of rat INS-1 islet β cells and the underlying mechanism. TXNIP overexpressing adenovirus vectors（Ad-TXNIP-GFP and Ad-TXNIPc247s-GFP） were constructed and used to infect INS-1 cells. Ad-TXNIPc247s-GFP vector carries a mutant C247S TXNIP gene, and its expression product（TXNIPc247s） cannot attach and inhibit Trx activity. The expression of TXNIP was detected by real-time PCR and Western blot. EdU and Ki67 methods were used to detect cell proliferation. Protein phosphorylation levels of ERK and AKT were detected by Western blot. The results showed that both TXNIP and TXNIPc247s protein overexpressions inhibited the proliferation of INS-1 cells, and the former＇s inhibitory effect was greater. Moreover, both of the two kinds of overexpressions inhibited the phosphorylation of ERK and AKT. These results suggest that TXNIP overexpression may inhibit the proliferation of INS-1 cells through Trx-dependent and non-Trx-dependent pathways, and the mechanism involves the inhibition of ERK and AKT phosphorylation.