RESUMO
Organovanadium compounds have been shown to be insulin sensitizers in vitro and in vivo. One potential biochemical mechanism for insulin sensitization by these compounds is that they inhibit protein tyrosine phosphatases (PTPs) that negatively regulate insulin receptor activation and signaling. In this study, bismaltolato oxovanadium (BMOV), a potent insulin sensitizer, was shown to be a reversible, competitive phosphatase inhibitor that inhibited phosphatase activity in cultured cells and enhanced insulin receptor activation in vivo. NMR and X-ray crystallographic studies of the interaction of BMOV with two different phosphatases, HCPTPA (human low molecular weight cytoplasmic protein tyrosine phosphatase) and PTP1B (protein tyrosine phosphatase 1B), demonstrated uncomplexed vanadium (VO(4)) in the active site. Taken together, these findings support phosphatase inhibition as a mechanism for insulin sensitization by BMOV and other organovanadium compounds and strongly suggest that uncomplexed vanadium is the active component of these compounds.
Assuntos
Hipoglicemiantes/química , Pironas/química , Vanadatos/química , Animais , Ligação Competitiva , Cristalografia por Raios X , Sinergismo Farmacológico , Humanos , Hipoglicemiantes/farmacologia , Insulina/farmacologia , Estrutura Molecular , Miocárdio/química , Ressonância Magnética Nuclear Biomolecular , Ligação Proteica , Proteína Tirosina Fosfatase não Receptora Tipo 1 , Proteínas Tirosina Fosfatases/antagonistas & inibidores , Proteínas Proto-Oncogênicas , Pironas/farmacologia , Ratos , Receptor de Insulina/agonistas , Vanadatos/farmacologiaRESUMO
Protein tyrosine phosphatases (PTPs) play roles in many biological processes and are considered to be important targets for drug discovery. As inhibitor development has proven challenging, crystal structure-based design will be very helpful to advance inhibitor potency and selectivity. Successful application of protein crystallography to drug discovery heavily relies on high-quality crystal structures of the protein of interest complexed with pharmaceutically interesting ligands. It is very important to be able to produce protein-ligand crystals rapidly and reproducibly for as many ligands as necessary. This study details our efforts to engineer the catalytic domain of human protein tyrosine phosphatase beta (HPTPbeta-CD) with properties suitable for rapid-turnaround crystallography. Structures of apo HPTPbeta-CD and its complexes with several novel small-molecule inhibitors are presented here for the first time.