Identification And Characterization Of PTPσ Small Molecular Inhibitor

PTPσ(Protein Tyrosine Phosphatase sigma), which is a classical receptor type tyrosine phosphatase in PTPs (Protein Tyrosine Phosphatases) superfamily, plays a key negative regulatory role in axon regrowth after nerves injury and might be a new potential target for neural regeneration. Identification and development of high affinity, bioavailability and specificity inhibitor of PTPσmay provides new inspects for research into mechanisms and therapeutic interventions to enhance regeneration or plasticity after nervous system injury. However, there is no inhibitor of PTPa reported so far.Here we developed high throughput screening assay for PTPσinhibitor. Through high throughput screening of 67472 compounds from National Center for Drug Screening and extra compounds from cooperative labs, we identified a series of inhibitors, some of which have IC50 lower than 1μM. Among these inhibitors, GM446-2 was chosen as a representative for further mechanism study. Selectivity studies suggest that GM446-2 inhibits both the entire intracellular domains and the membrane proximal domain in mouse PTPσand human PTPσ. Kinetic studies demonstrate that GM446-2 is a noncompetitive inhibitor. Furthermore, the crystal structure of PTPσin complex with GM446-2 suggests that the inhibitor is in the pocket formed by two face to face active sits of two enzyme molecules and interacts with the two molecules by hydrogen bonds andπbonds. The structural result indicates that GM446-2 may prevent the enzyme from hydrolyzing substrate by allosteric regulation in order to inhibite the activity of PTPσ.In conclusion, the project developed high throughput screening assay for PTPa inhibitor, identified PTPσinhibitor for the first time and characterized the inhibition mechanism via biochemical and structural studies. All these work may provide basis for compounds structure modification and in vivo activity evaluation. In addition, it also gives clues to develop new lead compounds for promoting neural regeneration. Therefore, the project has very important value in study as well as application prospect.