Study On The Relationship Between Insulin-resistance And The Changes Of FKBP12 Expression At The Transcription Level In VEC Proliferation

Hypertension,diabetes and cardiovascular disease (CVD) spring from a "common soil" ,that is, insulin-resistance (IR). The insulin-resistance syndrome (IRS) consists of glucose intolerance, hyperinsulinemia, dyslipidemia (high triglyceride and low high-density lipoprotein [HDL] cholesterol levels), and hypertension. Factors associated with insulin resistance, which was found to be a risk factor for development of hypertension, precede hypertension. Resistance to insulin-stimulated glucose uptake is present in the majority of patients with impaired glucose tolerance (IGT) or non-insulin-dependent diabetes mellitus (NIDDM) and in approximately 25% of nonobese individuals with normal oral glucose tolerance. All of the elements of the IRS have been documented as risk factors for type II diabetes. Some, but not all, of these elements are also cardiovascular disease risk factors, in particular, hypertension and low HDL cholesterol. Unlike classical microvascular complications, large-vessel atherosclerosis can precede the development of diabetes. For this reason, a deeper understanding of the relationship between IR and vascular endothelial cell (VEC) insulin receptor (InsR) will be helpful to explain the pathogenesis of IR and offer an experimental basis in the treatment of hypertension, diabetes and CVD.In this study, rat vascular endothelial cells were cultured with enzyme digesting methods,and were identified by measuring their growth states with invertmicroscope, by using immuocytochemical methods with factor Ⅷ antibody.We have investigated the expressions of FKBP12 in VEC proliferation induced by endothelial cell growth factor (ECGF) and the effect of insulin in different concentration on the expression of insulin receptor and its mRNA levels in vascular endothelial cell proliferation by means of cell culture,semi-quantitative RT-PCR,immuocytochemical methods and so on.The main results are as follows: (1) We used primary cultures aortic vascular endothelial cells, 100% of which stained with factor VIII, a marker for endothelial cell, and FK506 binding protein 12(FKBP12), consistent with one report (Am J Surg Pathol. 2003;27:58 -64).(2) After passage, the expression level of FKBP12 mRNA reached a peak in 4 day, and then decreased in 6～8 day. We conclude FKBP12 may play a role in the VEGF-induced vascular endothelial proliferation. However, direct proof, using gene-silencing techniques, needs to be undertaken. The upstream and down-stream transduction signals of FKBP also will be investigated. The expression of FKBP12 may be a new better maker.(3) The expression of insulin receptor (InsR), which was reduced in 1000μU/ml insulin groups, was observed in cultured endothelial cells. Endothelial cell is a kind of the insulin-sensitive cells.(4) The expressions of InsR and its mRNA decreased and VEC proliferation and NO production of culture medium were inhibited in 1000μU/ml insulin groups. VECs exposed to 1000μU/ml insulin for 16 hours were able to induce a state of insulin resistance which could be maintained for at least 24h. Compared with the classical definition of insulin resistance (Insulin resistance may be considered to exist whenever normal concentrations of insulin produce a less than normal biologic response), this study, to a certain degree, constructs VEC of insulin resistance. (5) The degree of VEC insulin resistance may carry out though the change of FKBP12 expression at the transcription level. FKBP12 could eventually play a critical role in insulin resistance of VEC exposed to 1000μU/ml insulin.