Screening Inhibitors Of Protein Tyrosine Phosphatase 1B

Protein tyrosine phosphatase 1B (PTP1B) is one of the protein tyrosinephosphatase (PTPs) family and the first separated PTP. Recent years, it hasbeen proved that PTP1B is a potential target of treatment of type â…¡ diabetesand obesity by knock-out mice model.PTP1B blocks the insulin signal pathways by dephosphorylating insulinreceptor (IR) and insulin receptor substrates (IRS), because dephosphorylationof IR and IRS affects the phosphorylation level of AKT and Erk. Decrease ofAKT phosphorylation affects the activity of glucose transporter-4(GLUT-4)which translocates the glucose into cells, so the level of blood glucoseincreases. Moreover, AKT regulates the glycogen synthesis, fatty acidsynthesis and protein synthesis, and plays an important role in cellularmetabolism. Extracellular Signal-regulated Kinases 1/2(Erk1/2) turns to bePhosphated Etracellular Signal-regulated Kinases 1/2 (pErk1/2), and pErkcould enter cell nucleus and affect the express and translation of gene.It becomes popular that screening the potent and selective inhibitors ofPTP1B as therapeutic drugs of type â…¡ diabetes. There are two problems aboutthe research: one is most obtained inhibitors have low specific to PTP1B,another is some inhibitors have the side effects to human body. The character of PTP1B was performed in vitro. IC₅₀ of compound A toâ–³PTP1B, which is the catalytic domain of human PTP1B, was measured byspectrophotometer. The results shows that the IC₅₀ of compound A toâ–³ PTP1B is 0.01μM. The inhibition type of compound A to â–³PTP1B iscompetition inhibition, and the Ki value is 0.05μM. Consequently, compoundA is a high selective inhibitor to â–³P TP1B contrasting with SHP1.The lysis solution of compound A treated NIH3T3 cells was separated bySDS-PAGE. The proteins were transferred to PVDF by trarsmembraneelectrophoresis bath. The PVDF treated with anti-pTyr,anti-pErk and anti-Erkantibodies was analysed . The phosphorylation level of cells treated withcompound A is much higher than those without treated and the results are thesame with insulin treated ones. So we can make a conclusion that compoundA can penetrate the cell membrane and inhibit the activity of endogenousPTP1B.Mice were used for diabetic induction by tail vein injections of alloxan. Theblood glucose level was detected by using glucose oxidase method. Modelmice were fed with compound A and detected the changes of blood glucose.The results show that the blood glucose of model mice without feedingcompound A increase, while the blood glucose decrease when fed compound A.The conclusion is that compound A could decrease the blood glucose level, andit is helpful to treat type â…¡ diabetes.Finally, we get the conclusion that compound A can block the activity ofPTP1B, decrease the blood glucose level and increase the sensitivity to insulinin vivo. Compound A is a potent and selective competition inhibitor to PTP1Bwhich is a potential target to exploit therapeutic drugs to type â…¡ diabetes.