Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear.It has been postulated that an increase in the intracell...Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear.It has been postulated that an increase in the intracellular concentration of fatty acid metabolites activates a serine kinase cascade,which leads to defects in insu-lin signaling downstream to the insulin receptor.In addition,the complex network of adipokines released from adipose tissue modulates the response of tissues to insulin.Among the many molecules involved in the intracellular processing of the signal provided by insulin,the insulin receptor substrate-2,the protein kinase B and the forkhead transcription factor Foxo 1a are of particular interest,as recent data has provided strong evidence that dysfunction of these proteins results in insulin resistance in vivo.Recently,studies have revealed that phosphoinositidedependent kinase 1-independent phosphorylation of protein kinase Cε causes a reduction in insulin receptor gene expression.Additionally,it has been suggested that mitochondrial dysfunction triggers activation of several serine kinases,and weakens insulin signal transduction.Thus,in this review,the current developments in understanding the pathophysiological processes of insulin resistance in type 2 diabetes have been summarized.In addition,this study provides potential new targets for the treatment and prevention of type 2 diabetes.展开更多
目的通过苦瓜总皂苷对2型糖尿病大鼠蛋白激酶B(PKB或Akt-2)和腺苷酸活化蛋白激酶(AMPK)的作用来揭示其改善胰岛素抵抗的机制。方法用高脂高糖饮食喂养结合小剂量链脲佐菌素注射,来复制2型糖尿病模型。按照体重随机分为6组:正常组、模型...目的通过苦瓜总皂苷对2型糖尿病大鼠蛋白激酶B(PKB或Akt-2)和腺苷酸活化蛋白激酶(AMPK)的作用来揭示其改善胰岛素抵抗的机制。方法用高脂高糖饮食喂养结合小剂量链脲佐菌素注射,来复制2型糖尿病模型。按照体重随机分为6组:正常组、模型组、对照组和3个剂量实验组,对照组和3个剂量实验组大鼠每天分别给予50 mg·kg-1二甲双胍2 m L和3个剂量(100,200,400 mg·kg-1)苦瓜总皂苷2 m L,灌胃8周。用生化分析仪检测空腹血糖,用酶联免疫吸附试验检测胰岛素,用RT-PCR和Western Blot法检测肝组织Akt-2和AMPK的mRNA和蛋白表达量。结果 3个剂量实验组稳态胰岛素抵抗评价指数较模型组明显降低,Akt-2和AMPK的mRNA和蛋白表达量较模型组明显增高。结论苦瓜总皂苷改善胰岛素抵抗的作用机制可能为上调Akt-2和AMPK的mRNA以及蛋白表达量。展开更多
AIM:To study the effects of hypoxia-inducible factor1α(HIF-1α) silencing on the proliferation of hypoxic CBRH-7919 rat hepatoma cells.METHODS:The CBRH-7919 rat hepatoma cell line was used in this study and the hypox...AIM:To study the effects of hypoxia-inducible factor1α(HIF-1α) silencing on the proliferation of hypoxic CBRH-7919 rat hepatoma cells.METHODS:The CBRH-7919 rat hepatoma cell line was used in this study and the hypoxic model was constructed using CoCl2.The HIF-1α-specific RNAi sequences were designed according to the gene coding sequence of rat HIF-1α obtained from GeneBank.The secondary structure of the HIF-1α gene sequence was analyzed using RNA draw software.The small interfering RNA(siRNA) transfection mixture was produced by mixing the siRNA and Lipofectamine2000TM,and transfected into the hypoxic hepatoma cells.Real time reverse transcription-polymerase chain reaction(RTPCR) and Western blotting assay were used to detect the expression levels of mRNA and protein.HIF-1α and vascular endothelial growth factor(VEGF) mRNA was determined using real time RT-PCR;the protein expression levels of AKT,p-AKT,p21 and cyclinD1 were determined using Western blotting.The proliferation of hepatoma cells was observed using the methyl thiazolyl tetrazolium(MTT) assay and the bromodeoxyuridine(BrdU) incorporation cell proliferation assay.RESULTS:Under induced hypoxia,the viability of the hepatoma cells reached a minimum at 800 μmol/L CoCl2;the viability of the cells was relatively high at CoCl2 concentrations between 100 μmol/L and 200 μmol/L.Under hypoxia,the mRNA and protein expression levels of HIF-1α and VEGF were significantly higher than that of hepatoma cells that were cultured in normaxia.HIF-1α-specific RNAi sequences were successfully transfected into hepatoma cells.The transfection of specific siRNAs significantly inhibited the mRNA and protein expression levels of HIF-1α and VEGF,along with the protein expression levels of p-AKT and cyclinD1;the protein expression of p21 was significantly increased,and there was no significant difference in the expression of AKT.The MTT assay showed that the amount of hepatoma cells in S phase in the siRNA transfection group was obviously smaller than that in the contro展开更多
文摘Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear.It has been postulated that an increase in the intracellular concentration of fatty acid metabolites activates a serine kinase cascade,which leads to defects in insu-lin signaling downstream to the insulin receptor.In addition,the complex network of adipokines released from adipose tissue modulates the response of tissues to insulin.Among the many molecules involved in the intracellular processing of the signal provided by insulin,the insulin receptor substrate-2,the protein kinase B and the forkhead transcription factor Foxo 1a are of particular interest,as recent data has provided strong evidence that dysfunction of these proteins results in insulin resistance in vivo.Recently,studies have revealed that phosphoinositidedependent kinase 1-independent phosphorylation of protein kinase Cε causes a reduction in insulin receptor gene expression.Additionally,it has been suggested that mitochondrial dysfunction triggers activation of several serine kinases,and weakens insulin signal transduction.Thus,in this review,the current developments in understanding the pathophysiological processes of insulin resistance in type 2 diabetes have been summarized.In addition,this study provides potential new targets for the treatment and prevention of type 2 diabetes.
文摘目的通过苦瓜总皂苷对2型糖尿病大鼠蛋白激酶B(PKB或Akt-2)和腺苷酸活化蛋白激酶(AMPK)的作用来揭示其改善胰岛素抵抗的机制。方法用高脂高糖饮食喂养结合小剂量链脲佐菌素注射,来复制2型糖尿病模型。按照体重随机分为6组:正常组、模型组、对照组和3个剂量实验组,对照组和3个剂量实验组大鼠每天分别给予50 mg·kg-1二甲双胍2 m L和3个剂量(100,200,400 mg·kg-1)苦瓜总皂苷2 m L,灌胃8周。用生化分析仪检测空腹血糖,用酶联免疫吸附试验检测胰岛素,用RT-PCR和Western Blot法检测肝组织Akt-2和AMPK的mRNA和蛋白表达量。结果 3个剂量实验组稳态胰岛素抵抗评价指数较模型组明显降低,Akt-2和AMPK的mRNA和蛋白表达量较模型组明显增高。结论苦瓜总皂苷改善胰岛素抵抗的作用机制可能为上调Akt-2和AMPK的mRNA以及蛋白表达量。
基金Supported by Natural Science Foundation of Guangdong Province People’s Republic of China,No. 10151008901000182
文摘AIM:To study the effects of hypoxia-inducible factor1α(HIF-1α) silencing on the proliferation of hypoxic CBRH-7919 rat hepatoma cells.METHODS:The CBRH-7919 rat hepatoma cell line was used in this study and the hypoxic model was constructed using CoCl2.The HIF-1α-specific RNAi sequences were designed according to the gene coding sequence of rat HIF-1α obtained from GeneBank.The secondary structure of the HIF-1α gene sequence was analyzed using RNA draw software.The small interfering RNA(siRNA) transfection mixture was produced by mixing the siRNA and Lipofectamine2000TM,and transfected into the hypoxic hepatoma cells.Real time reverse transcription-polymerase chain reaction(RTPCR) and Western blotting assay were used to detect the expression levels of mRNA and protein.HIF-1α and vascular endothelial growth factor(VEGF) mRNA was determined using real time RT-PCR;the protein expression levels of AKT,p-AKT,p21 and cyclinD1 were determined using Western blotting.The proliferation of hepatoma cells was observed using the methyl thiazolyl tetrazolium(MTT) assay and the bromodeoxyuridine(BrdU) incorporation cell proliferation assay.RESULTS:Under induced hypoxia,the viability of the hepatoma cells reached a minimum at 800 μmol/L CoCl2;the viability of the cells was relatively high at CoCl2 concentrations between 100 μmol/L and 200 μmol/L.Under hypoxia,the mRNA and protein expression levels of HIF-1α and VEGF were significantly higher than that of hepatoma cells that were cultured in normaxia.HIF-1α-specific RNAi sequences were successfully transfected into hepatoma cells.The transfection of specific siRNAs significantly inhibited the mRNA and protein expression levels of HIF-1α and VEGF,along with the protein expression levels of p-AKT and cyclinD1;the protein expression of p21 was significantly increased,and there was no significant difference in the expression of AKT.The MTT assay showed that the amount of hepatoma cells in S phase in the siRNA transfection group was obviously smaller than that in the contro
