调节内质网应激对糖尿病小鼠肾脏SET7/9表达的影响

目的 探讨调节内质网应激对小鼠肾组织组蛋白甲基转移酶(HMT) SET7/9表达的影响及意义.方法 db/db小鼠按随机数字表法分为糖尿病肾病(DN)组和甜菜碱治疗(DN+B)组；db/m小鼠作为正常对照(NC)组,每组各18只.实验第4、8、12周末分别采用实时定量PCR和(或)Western印迹法测定小鼠肾组织SET7/9、葡萄糖调节蛋白(GRP)78、H3K4me2和单核细胞趋化蛋白1(MCP-1)表达水平；ELISA法测定24 h尿蛋白排泄率(UPER)和尿MCP-1浓度；全自动生化分析仪检测血糖(BG)、血肌酐、血尿素氮的动态改变；PAS染色观察肾脏病理改变.结果 与NC组比较,DN组BG、BUN、UPER、MCP-1均显著升高(均P＜0.05),且呈时间依赖性.DN组小鼠第4周末开始出现肾小球基底膜增厚、系膜细胞增生改变,第12周末出现明显系膜基质积聚.与NC组比较,DN组肾组织GRP78、SET7/9的mRNA和蛋白质表达水平均显著升高,H3K4me2蛋白水平也显著升高,且呈时间依赖效应.与DN组比较,甜菜碱治疗组小鼠肾小球病变明显减轻,GRP78、SET7/9的mRNA及蛋白表达水平显著降低,BG、BUN、UPER、MCP-1、H3K4me2水平显著降低(均P＜0.05).结论 内质网应激可能是介导糖尿病小鼠肾脏SET7/9表达的上游机制.

Effect of regulating endoplasmic reticulum stress on the expression of SET7/9 in the kidneys of db/db mice with diabetic nephropathy

Objective To investigate the effect and significance of regulating endoplasmic reticulum stress on the expression of histone methyltransferases SET7/9 in the kidneys of db/db mice. Methods Db/db mice were randomly divided into two groups according to random number table method: diabetic nephropathy model group (DN group, n＝18) and betaine treatment group (DN+B group, n＝18), db/m mice were defined as normal control group (NC group, n＝18). At the end of 4, 8 and 12 weeks, the expression of GRP78, SET7/9, H3K4me2, and monocyte chemoattractant protein 1(MCP-1) was determined by real-time fluorescence PCR and Western blotting. 24?hour urinary protein excretion rate (UPER) and urine MCP-1 were measured by enzyme linked immunosorbent assay (ELISA). The dynamic changes of blood glucose(BG), serum creatinine (Scr), blood urea nitrogen (BUN) were tested by completely automatic biochemistry analyzer. The morphology of kidney was estimated by special staining of periodic acid-schiff (PAS). Results The levels of BG, BUN, UAER and MCP-1 were significantly higher in DN group than those in NC group (P＜0.05), and were in time?dependent manner. Glomerular basement membrane thickening and mesangial cells proliferation began to emerge in DN group at the end of week 4 and mesangial matrix expansion was more obvious at the end of week 12. The mRNA and protein expression of GRP78 and SET7/9 were elevated significantly in DN group as compared to NC group. The H3K4me2 protein expression level was also increased in time-dependent manner. Compared with the DN group, in DN+B group glomerular lesions attenuated and the GRP78 and SET7/9 expression levels obviously decreased (P＜0.05). Furthermore, the levels of BG, BUN, UPER, MCP-1, H3K4me2 in DN+B group were also reduced (P＜0.05). Conclusion Endoplasmic reticulum stress may be the upstream mechanism of mediating the expression of SET7/9 in the kidneys of DN mice.