ABSTRACT
The increasing prevalence of type 2 diabetes has sparked interest in the development of agents that treat and prevent the disease. Mounting evidence indicates that protein tyrosine phosphatase (PTP)1B negatively regulates insulin and leptin signaling making it a prime target for enhancing insulin sensitivity and controlling body mass. Despite intense efforts, development of orally bioavailable small-molecule PTP1B inhibitors has been a challenge. This review focuses on recent advances in the validation of PTP1B and in the development of approaches to modulate its activity.
Subject(s)
Diabetes Mellitus, Type 2/drug therapy , Hypoglycemic Agents/therapeutic use , Insulin/physiology , Protein Tyrosine Phosphatase, Non-Receptor Type 1/antagonists & inhibitors , Animals , Diabetes Mellitus, Type 2/enzymology , Humans , Leptin/physiology , Protein Tyrosine Phosphatase, Non-Receptor Type 1/genetics , Protein Tyrosine Phosphatase, Non-Receptor Type 1/metabolism , Signal TransductionABSTRACT
High-throughput screening of the P&GP corporate repository against several protein tyrosine phosphatases identified the sulfamic acid moiety as potential phosphotyrosine mimetic. Incorporation of the sulfamic acid onto a 1,2,3,4-tetrahydroisoquinoline scaffold provided a promising starting point for PTP1B inhibitor design.
Subject(s)
Enzyme Inhibitors/pharmacology , Protein Tyrosine Phosphatases/antagonists & inhibitors , Sulfonic Acids/pharmacology , Tetrahydroisoquinolines/chemistry , Binding Sites , Binding, Competitive , Crystallography, X-Ray , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Humans , Ligands , Models, Molecular , Molecular Mimicry , Phosphotyrosine/metabolism , Protein Binding , Protein Tyrosine Phosphatase, Non-Receptor Type 1 , Protein Tyrosine Phosphatases/chemistry , Protein Tyrosine Phosphatases/metabolism , Structure-Activity Relationship , Sulfonic Acids/chemical synthesis , Sulfonic Acids/chemistry , src Homology DomainsABSTRACT
The molecular basis of insulin resistance, a major risk factor for development of Type II diabetes, involves defective insulin signaling. Insulin-mediated signal transduction is negatively regulated by the phosphotyrosine phosphatase, PTP1B, and numerous studies have demonstrated that organo-vanadium compounds, which are nonselective phosphotyrosine phosphatase inhibitors, have insulin-mimetic properties. However, whether or not vanadium compounds can prevent the transition from insulin resistance to overt diabetes is unknown. We compared the ability of bis(maltolato)oxovanadium(IV) (BMOV), an orally bioavailable organo-vanadium compound, and rosiglitazone maleate (RSG), a known insulin sensitizer, to prevent development of diabetes in Zucker diabetic fatty (ZDF) rats. Treatment began at 6 weeks of age when animals are insulin resistant and hyperinsulinemic, but not yet hyperglycemic, and ended at 12 weeks of age, which is 4 weeks after ZDF rats typically develop overt diabetes. BMOV-treated ZDF rats did not develop hyperglycemia, showed significant improvement in insulin sensitivity, and retained normal pancreatic islet morphology and endocrine cell distribution, similar to RSG-treated animals. BMOV and RSG treatment also prevented the hyper-phagia and polydipsia present in untreated ZDF rats; however, BMOV-treated ZDF rats gained much less weight than did RSG-treated animals. Circulating levels of adiponectin decreased in untreated ZDF rats compared to lean controls, but these levels remained normal in BMOV-treated ZDF rats. In contrast, in RSG-treated ZDF rats, plasma adiponectin levels were nearly 4-fold higher than in lean control rats, primarily as a result of a large increase in the amount of low-molecular weight forms of adiponectin in circulation. These data demonstrate that phosphatase inhibition offers a new approach to diabetes prevention, one that may have advantages over current approaches.
