糖基化终末产物对大鼠肾小管上皮细胞组织型转谷氨酰胺酶mRNA表达的影响

目的探讨晚期糖基化终末产物(Advanced glycosylation end products,AGEs)对大鼠肾小管上皮细胞NRK-52E组织型转谷氨酰胺酶(Tissue transglutanunase,tTG)mRNA表达及其对细胞外基质(Extracellular matrix,ECM)降解的影响。方法体外培养NRK-52E细胞,分别用体外合成的不同浓度的糖化牛血清白蛋白(AGE-BSA)及未经糖化的牛血清白蛋白(BSA)处理48h,ELISA法检测细胞培养上清中纤维连接蛋白(Fibronectin,FN)和Ⅳ型胶原蛋白(TypeⅣcollagen,ColⅣ)含量,RT-PCR检测细胞tTG mRNA的表达。结果与BSA组比较,50～200mg/LAGE-BSA组细胞上清中FN含量明显增加(P<0.01),25～100mg/L AGE-BSA组细胞上清中ColⅣ含量明显增加(P<0.05);AGE-BSA(50～400mg/L)可不同程度地刺激细胞tTG mRNA表达的增加(P<0.05);tTG mRNA表达增加与FN、ColⅣ分泌增多呈正相关(r值分别为0.911和0.872)。结论 AGEs能诱导大鼠近端肾小管上皮细胞tTG mRNA的表达,引起ECM主要成分FN和ColⅣ含量增加,提示tTG可能在AGEs引起的ECM积聚过程中,起到抑制ECM蛋白降解的作用,进而参与糖尿病肾病的病理过程。

Effect of Advanced Glycosylation End Products on Expression of Tissue Transglutaminase mRNA in Rat Proximal Tubular Epithelial Cells

Objective To investigate the effect of advanced glycosylation end products(AGEs)on the expression of tissue transglutaminase(tTG)mRNA in rat proximal tubular epithelial cells NRK-52E as well as on the degradation of extracellular matrix(ECM).Methods NRK-52E cells were cultured in vitro,then treated with various concentrations of AGE-BSA and BSA synthesized in vitro for 48 h respectively.The fibronectin(FN)and type Ⅳ collagen(Col Ⅳ)contents in supernatant of cell culture were determined by ELISA,while the expression of tTG mRNA by RT-PCR.Results Compared with those treated with BSA,the FN content in supernatant of cells treated with 50 ～ 200 mg /L AGE-BSA increased significantly(P < 0.01),and the Col Ⅳ content in those treated with 25～100 mg /L AGE-BSA increased significantly(P < 0.05).The increase of expressed tTG mRNA was positively related to the increase of secreted FN(r = 0.911)and Col Ⅳ(r = 0.872).Conclusion AGEs induced the expression of tTG mRNA in rat proximal tubular epithelial cells and increased the contents of FN and Col Ⅳ as major components of ECM,indicating that tTG might inhibit the degradation of ECM during cumulation of ECM caused by AGEs and be involved in the pathogenesis of diabetic nephropathies.