| In our laboratory, FANG Ding Zhi et al constructed forward-subtracted and backward-subtracted cDNA libraries of differentially expressed genes in the. liver of rats that had some features of metabolic syndrome (MS). With the differentially expressed ESTs from the libraries, they cloned a new cDNA from human hepatic cDNA library. This new cDNA was temporarily named as metabolic syndrome related gene (MSRG). To investigate functions of the new gene and identify its possible roles in the development of MS and artherosclerosis (AS), we first studied the factors that affect the expression MRSG. The presentstudy is to explore the effects of glucose, insulin, and glycagon on the expression of MRSG in HepG2 human hepatoma cellsand the relationship of MRSG expression with the levels of glucose, glucogen, triglyceride, and cholesterol in the cells, the levels of triglyceride and cholesterol in the medium, and the uptake of glucose by the cells.In part one, we designed the specific primers and probe for real-time PCR according to the MRSG cDNA sequence, selectedβ-actin as intra-reference, and established an effective real-time PCR assay for detecting the MRSG mRNA levels. HepG2 cells were cultured with glucose, insulin, and glycagon respectively at different concentrations (glucose: 2.8, 5.6, 11.1, 22, and 33.3 mmol/L using mannitol as control of osmotic pressure; insulin: 0, 10-10, 10-9, 10-8, 10-7, and 10-6 mol/L; glycagon: 0,10-11,10-10,10-9,10-8, 10-7, and 10-6 mol/L) for 48 hours. The mRNA levels of MSRG were measured in HepG2 cells by Taqman real-time PeR. When incubated with high levels of glucose, the mRNA levels of MSRG in HepG2 cells increased significantly. The mRNA levels of MSRG decreasd significantly when the cells were incubated with insulin at 10-7 and 10-6 mol/L. No effect of mannitol and glycagon was found on the levels of MSRG mRNA.To further study the function of MSRG, wefurther incubated the cells with 5.6, 22, and 33.3 mmol/L glucose, and 0,10-7, and 10-9 mol/L insulin to Study the relationship of MRSG expression with the levels of glucose, glucogen, triglyceride, and cholesterol in the cells, the levels of triglyceride and cholesterol in the medium, and the uptake of glucose by the cells in the second part of our experiment, because the mRNA levels had been found significantly changed when HepG2 cells were cultured with glucose and insulin at these points of concentration. The mRNA levels of MSRG were measured by Taqman real-time PeR, and the levels of glucose, glucogen, triglyceride, cholesterol in cells and medium were quantified at the same time. The result Showed that the mRNA levels of MSRG in HepG2 cells increased significantly when the cells were incubated with high glucose level, meanwhile the levels of glucose, glucogen, and triglyceride in the cells, and triglyceride in the medium increased significantly. MSRG mRNA was down-regulate when the cells were treated with 10-7 mol/L insulin, and the levels of glucose, glucogen, and triglyceride in the cells, and triglyceride in the medium increased significantly. But the level of glucose in the medium decreased significantlyat the same time.
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