The Basic And Clinical Study Of FABP4and PTEN In Type2Diabetes Mellitus

Background and Objects Type2diabetes is an increasing worldwide diease that poses major health problems. Over the past decade, a large body of evidence has emerged demonstrating an important role of FABP4and PTEN in the occurrence of type2diabetes. Recent reports suggest that the tumor-suppressor PTEN is a negative regulator of the phosphatidylinositol-3-kinase/AKT pathway and an important modulator of insulin signaling. PTEN-FABP4complex formation in3T3-L1adipocytes has been found using coimmunoprecipitation and gel-filtration assays, which provides an evidence of interaction between PTEN and FABP4in differentiated3T3-L1adipocytes[1].The study is to investigate the correlation between gene expressions of FABP4and PTEN in the process of proliferation and differentiation of3T3-L1preadipocyte cells and whether the down regulation of FABP4affect the expression of PTEN and P-Akt in3T3-L1cells. It is also to observe the gene expressions of FABP4and PTEN and their correlation in the liver, muscle and adipose tissues of type2diabetes rats, and to observe the protein expressions of FABP4and PTEN in plasma of the impaired glucose regulation(IGR) patients, obese and non-obese groups of the newly-diagnosed type2diabetes mellitus(T2DM) patients, and the normal control group, then to determine whether there is a correlation between FABP4and PTEN in the occurrence of type2diabetes and whether the plasma FABP4and PTEN could be a potential marker of biochemistry, which may predict the occurrence of T2DM.Methods Part I SiRNA interference method was used to inhibit the expression of FABP4in3T3-L1preadipocyte cells, and subsequently to observe the changes of expression of PTEN and phosphorylated Akt by real-time PCR and Western blot. Part Ⅱ Of the24healthy Wistar rats,12rats were taken randomly as the control group and fed on basic diet for8weeks, while the other12rats were the experimental group (type2diabetes group) and fed on high fat and high sugar diet for8weeks. After having fasted for18hours, the rats of the both groups were weighed and then intraperitoneally injected with1%STZ solution and citrate buffer based on25mg/kg respectively. After72hours, when random blood glucose of the rats in the experimental group was higher than16.7mmol/L and insulin resistance was present at the same time(HOMA-IR≥2.69[2]), the rats were killed and their liver, muscle and adipose tissues were taken to detect the gene expressions of FABP4and PTEN by real-time PCR and to analyze their correlation.Part III65newly-diagnosed T2DM patients(34obese patients and31non-obese patients),32IGR patients and30healthy subjects were enrolled in this study who are all from the Affiliated Hospital to Inner Mongolia Medical University. Protein expressions of plasma FABP4and PTEN of IGR patients, T2DM patients and normal control group were detected respectively with enzyme-linked immunosorbent assay (ELISA); high performance liquid chromatography was used to determine HbAlc and COBAS C6000biochemical analyzer and matching reagent are used to detect FPG, FINS, TG, TC, HDL-C and LDL-C; HOMA-IR was calculated by HOMA steady-state model, body mass index(BMI) was collected too.Results Part I Inhibition of FABP4increased the expression of PTEN in the induced3T3-L1preadipocyte cells and also increased the gene expression of PTEN in the undifferentiated3T3-L1preadipocyte cells. The differences of protein expression of PTEN and P-Akt between FABP4interfered and control groups were not obvious in undifferentiated3T3-L1preadipocyte cells, but the expression of PTEN protein was significantly increased and P-Akt expression was reduced when FABP4was interfered in the induced3T3-L1preadipocyte cells. Part II The gene expressions of FABP4significantly increased in fat (5.17times),liver (1.43times) and muscle tissues (6.41times) of type2diabetes rats compared with those of the rats in the control group. The gene expressions of PTEN significantly increased in fat (2.6times), liver(2.25times)and muscle tissues(6.59times) of type2diabetes rats compared with those of the rats in the control group. There was a positive correlation (r=0.666,p<0.01) between the expression levels of FABP4and PTEN in fat tissues of type2diabetes rats, but there was no significant correlation between the expression levels of FABP4and PTEN in liver and muscle tissues (r=-0.043, P=0.854and r=0.415, p=0.140). Part III The plasma FABP4and PTEN levels in both IGR patients and obese and non-obese groups of T2DM patients are all significantly higher than those in normal control group (P<0.01); the levels of FABP4and PTEN were positively correlated in IGR patients (r=0.542, P=0.001) and obese group of T2DM patients (r=-0.448, P=0.008), but there was no significant correlation between the levels of FABP4and PTEN in normal control group (r=-0.078, P=0.682) and non-obese group of T2DM patients (r=-0.187,P=0.313); Multiple stepwise regression analysis showed that FABP4、TG、BMI and PTEN were independent variables of HOMA-IR.Conclusion The down regulation of FABP4can influence the expression of PTEN and P-Akt in differentiated3T3-L1preadipocyte. FABP4and PTEN are related to type2diabetes and there might be a correlation between FABP4and PTEN in the occurrence of T2DM. Both of them may be involved in the regulation of insulin signal pathway, and promoting the occurrence of type2diabetes. Elevated plasma FABP4and PTEN are closely related to glucose metabolism disorder and they might be considered to be the earlier markers of type2diabetes.