Wnt信号通路对体外培养小鼠NIT-1胰岛细胞PPARγ及葡萄糖激酶表达的影响

Influence of Wnt signaling pathway on peroxisome proliferator-activated receptor γ and glucokinase expression in mice NIT-1 β-cell cultured in vitro

目的 通过体外培养干预,研究激活Wnt信号通路对小鼠NIT-1胰岛细胞中PPARγ及葡萄糖激酶（Glucokinase,GK）表达的影响,探讨Wnt信号通路与PPARγ在胰岛细胞中的对话.方法 重组Wnt3a蛋白干预体外培养的小鼠NIT-1胰岛细胞,激活Wnt信号通路,荧光定量PCR及Western印迹方法比较PPARγ的mRNA及蛋白水平,荧光定量PCR方法比较GK的mRNA水平.结果 Wnt3a干预组细胞的PPARγ及GK的mRNA水平均较对照组增加41.2％和65.0％ （P＜0.01）,PPARγ蛋白表达亦明显增加（＜0.01）.予dickkopf 1阻断Wnt信号通路,PPARγ与GK的表达较Wnt3a干预组降低,激活Wnt通路同时以wortmannin阻断磷酸肌醇3激酶（PI3K）通路,PPARγ与GK的的表达亦较单纯Wnt3a干预组降低.同时阻断Wnt及PI3K通路时,PPARγ的蛋白水平较Wnt3a干预组下降的更为显著,且较单独阻断Wnt或PI3K信号通路时更明显.结论 激活Wnt信号通路,能够上调胰岛细胞PPARγ及GK的表达,且作用部分依赖于PI3K通路.

Objective To investigate the expression of peroxisome proliferator-activated rec eptor γ （PPARγ） and glucokinase （GK） induced by Wnt signaling pathway in mice NIT-1 β-cells,and to explore the interaction between PPARγ and Wnt signaling pathways.Methods Recombinant Wnt3a protein was applied to NIT-1 beta-cells to activate Wnt signaling pathway.The expression of PPARγ was determined by real-time PCR and Western blotting.The expression of GK was determined by real time PCR.Results Wnt3a rapidly activated Wnt/β-catenin/TCF signaling pathway,and increased PPARγ and GK mRNA expression by 41.2％ and 65.0％ in NIT-1cells,with PPARγ protein expression increasing by 97.8％ （P＜0.01）.These effects were abrogated by Wnt and PIK3 inhibitors,dickkopf 1 and wortmannin treatment （P＜ 0.01）.Conclusions PPARγ and GK can be upregulated by Wnt singnaling,and the effects might partially be PI3K-dependent.