Experimental Study Of Pancreatic β - Cell Protection Based On Target PTP1B And Drug Screening For Anti - Metabolic Syndrome

Abnormalities of islet may play a key role in the onset of T2DM, pancreatic β cell dysfunction is considered to play a main role in course of T2DM. Protein tyrosine phosphatase 1B (PTP1B), a key negative regulator of both insulin and leptin signaling pathways, is recognized as a molecular targets of insulin sensitizers. Inhibiting on PTP1B can improve insulin resistance, secondary to protect the β cell function. Recent research reveals that the pancreatic β cell mass and the glucose-stimulated insulin secretion were increased in PTP 1B-/- mice. This study is intended to investigate whether PTP1B is a potential target for the protection of pancreatic β cells.The β cell dysfunction mice model was induced by alloxan. The glucose stimulated insulin secretion (GSIS) test was utilized to estimate the β cell secretory function. The amount and the size of islets observed in pathological sections were calculated to evaluate the β cell mass. The oral glucose tolerance test (OGTT) was taken to observe the glucose metabolism in mice. The expressions of protein in pancreas were detected by western blotting (WB). The effects on the target PTP1B were assessed by the PTP1B activities, and by the PTP1B expression in the pancreas of mice, respectively. To observe the effects of compounds, which inhibit the activity of PTP1B in vitro, on metabolic syndrome, the blood glucose level, glucose tolerance test, insulin tolerance test, ISWBI index, and the levels of serum insulin, TC and TG were evaluated in high-fat-diet induced insulin resistant obesity (DIO) mice or diabetic KKAy mice, respectively.The results showed that compound CX09040 can inhibit the PTP1B activities of both recombinant protein in vitro and the intracellular enzyme in PTP1B overexpressed 293T cells. In β cell dysfunction mice, CX09040 can improve the impaired glucose tolerance, inhibit the expression of PTP1B in pancreas, up-regulate the phosphorylation of insulin receptor (IR), and its downstream Akt and FoxO1 which related to β cell proliferation, and increase the expression of PDX-1, respectively, thereby increasing the pancreatic β cell mass and glucose-stimulated insulin secretion. It is suggested that target PTP1B may play an important role in the protection of pancreatic β cell.The herbal extract RP2014006 shows strong inhibition on PTP1B in vitro. It can significantly improve glucose intolerance, increase the β cell mass, improve glucose-stimulated insulin secretion in the β cell dysfunction mice. Inhibition of target PTP1B and increase IR phosphorylation, then up-regulate the phosphorylation of IR, Akt, FoxO1 and the expression of PDX-1, may play an important role in protection of pancreatic β cell.Among the 13 compounds which showed PTP1B activity inhibition in vitro, CX14001 and CX09072 can improve the glucose intolerance and insulin resistance, respectively.In conclusion, PTP1B may be a new target for the protection of pancreatic β cell. Compound CX09040, CX14001, CX09072 and herbal extract RP2014006, which have inhibitory activity of PTP1B, shows a good prospect for developing anti-diabeic drugs. Chinese Academy of Medical Science & Peking Union Medical College...