| IntroductionResistin is a recently discovered polypeptide that induces insulin resistance in rodents. The function of resistin from human remains unclear. To study the effect of human resistin on type2 diabetes (T2DM) and coronary heart disease (CAD), we detected the changes of resistin level in the serum from patients with T2DM, T2DM with CAD respectively, and investigated the relationship between serum resistin and acute myocardial infarction (AMI), unstable angina pectoris (UAP) or stable angina pectoris (SAP). The potential target of resistin was detected by fluorescence staining, and the regulatory effect of human resistin on the transcription of human insulin receptor was determined by ligating the promoter of insulin receptor to luciferasereporter gene.Materials and Methods1. SubjectsTo detect the relationship of resistin to T2DM and T2DM with CAD, 38 T2DM with CAD patients, 40 patients with T2DM, and 34 healthy controls were recruited in the study of whether serum resistin differed between patients with T2DM, T2DM combining CAD and healthy. To detect the relationship of resistin to CAD, 65 patients with CAD, were enrolled and divided into three subgroups: AMI, UAP and SAP, and 26 healthy people were recruited as controls.2. MethodsSerum resistin levels were measured with ELISA and white blood count (WBC), high sensitive C-reaction protein(hsCRP), creatinkinase(CK), isozyme of creatinkinase (CK-MB), troponin (cTnI) were measured by standard laboratory methods.Eukaryotic expressing vectors such as pSecTag2B-RETN, pSecIRP-LUC, pSec-LUC, pSec0-LUC were constructed by molecular cloning. Resistin-fusion protein were expressed by stable transfection and confirmed by Western blotting. Immunofluorescence was used to locate where resistin is in the cell. Transient transfection assays were used to evaluate the effects of resistin on transcription of human insulin receptor gene promoter.Results1. Serum resistin level in T2DM and T2DM with CADSerum resistin level in T2DM and T2DM with CAD were significantly higher than that in the control (P<0.05); Serum resistin level in T2DM with CAD was elevated when compared to T2DM (P<0.05).2. Serum resistin level in AMI, UAP and SAPThe serum resistin level was 4 folds higher in AMI patients, 2.43 folds in UAP patients and 1.12 folds in SAP patients than that in the healthy controls (P<0.05).The resistin levels were also significantly different between AMI, UAP and SAP (P<0.01); WBC, hsCRP, CKmax, CK-MBmax and cTnImax were significantly increased in AMI patients over UAP and SAP patients. Spearman analysis showed that serum resistin level in AMI was positively correlated with WBC, hsCRP, CKmax, CK-MBmax and cTnImax (r=00412,0.427,0.731,0.678,0.656,respectively,P<0.01).3. The site of resistin in the cell and its regulation on transcription of insulin receptorResistin fusion-protein was successfully expressed and located at the area of cell nucleus by immunofluorescence staining. The treatment of pSecIRP-LUC transfected HepG2 with resistin showed no significant difference with the untreated transfectant (P>0.05).Conclusions1. Resistin has close relation to T2DM and CAD and may be responsible for insulin resistance and atherosclerosis. 2. Serum resistin level increased with inflammatory factors and myocardial impairment, suggesting that human resistin might play an important role in the pathogenesis of atherosclerosis and AMI as an inflammatory factor.3. Resistin secretes from its expressing tissue to the serum and locates at cell nucleus through the target cellular membrane.4. Resistin dosen't influence the activity of luciferase report gene, suggesting that the expression of insulin receptor in DNA level was not regulated by resistin. |
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