蛋白质酪氨酸磷酸酶1B（PTP1B）与2型糖尿病及肥胖的关系

蛋白质酪氨酸磷酸酶1B（PTP1B）是一种在体内广泛表达的胞内蛋白质酪氨酸磷酸酶,在调节胰岛素敏感性和能量代谢的过程中起着重要作用。通过抑制PTP1B可增加胰岛素和瘦蛋白（leptin）的活性, 为寻找2型糖尿病、肥胖的治疗提供了光明前景。     

The design strategy of selective PTP1B inhibitors over TCPTP

Protein tyrosine phosphatase 1B (PTP1B) has already been well studied as a highly validated therapeutic target for diabetes and obesity. However, the lack of selectivity limited further studies and clinical applications of PTP1B inhibitors, especially over T-cell protein tyrosine phosphatase (TCPTP). In this review, we enumerate the published specific inhibitors of PTP1B, discuss the structure–activity relationships by analysis of their X-ray structures or docking results, and summarize the characteristic of selectivity related residues and groups. Furthermore, the design strategy of selective PTP1B inhibitors over TCPTP is also proposed. We hope our work could provide an effective way to gain specific PTP1B inhibitors.     

Potent,selective inhibitors of protein tyrosine phosphatase 1B

We have previously reported a novel series of oxalyl-aryl-amino benzoic acid-based, catalytic site-directed, competitive, reversible protein tyrosine phosphatase 1B (PTP1B) inhibitors. With readily access to key intermediates, we utilized a solution phase parallel synthesis approach and rapidly identified a highly potent PTP1B inhibitor (19, K(i)=76 nM) with moderate selectivity (5-fold) over T-cell PTPase (TCPTP) through interacting with a second phosphotyrosine binding site (site 2) in the close proximity to the catalytic site.     

Ursolic acid and its derivative inhibit protein tyrosine phosphatase 1B, enhancing insulin receptor phosphorylation and stimulating glucose uptake

Protein tyrosine phosphatase 1B (PTP1B) is a key element in the negative regulation of the insulin signaling pathway and may play an important role in diabetes and obesity. We identified ursolic acid, a natural pentacyclic triterpenoid that occurs widely in traditional Chinese medicinal herbs, as an inhibitor of PTP1B by screening an extract library of the traditional Chinese medicinal herbs used a diabetes clinic. By modifying urosolic acid, we designed and synthesized a derivative with a K(i) of 283 nM. As competitive inhibitors of PTP1B, ursolic acid and its derivative also inhibit T-cell protein tyrosine phosphatase and src homology phosphatase-2 but not leucocyte antigen-related phosphatase or protein tyrosine phosphatase alpha and epsilon, which are all possibly involved in the insulin pathway. The ursolic acid derivative enhanced insulin receptor phosphorylation in CHO/hIR cells and stimulate glucose uptake in L6 myotubes.     

Enzyme occupancy measurement of intracellular protein tyrosine phosphatase 1B using photoaffinity probes

Protein tyrosine phosphatase 1B (PTP1B) is believed to be one of the enzymes involved in down-regulating the insulin receptor and is a drug target for the treatment of type II diabetes. To better understand the in vitro and in vivo behavior of PTP1B inhibitors, a cell-based assay to directly measure enzyme occupancy of PTP1B by inhibitors using photoaffinity labeling was developed. Two photoaffinity probes were synthesized containing the photolabile diazirine moiety. These photoprobes were specific for PTP1B and T-cell protein tyrosine phosphatase over CD45, with the most potent photoprobe having an IC(50) value of 0.2nM for PTP1B. Activation of the photoprobes with a 40-W UV lamp in the presence of purified AspTyrLysAspAspAspAspLys (Flag)-PTP1B formed a 1:1 irreversible adduct with the enzyme. The photolabeling was competed by known PTP1B inhibitors, vanadate, and the peptide inhibitor N-benzoyl-l-glutamyl-[4-phosphono(difluoromethyl)]-l-phenylalanyl-[4-phosphono(difluoromethyl)]l-phenylalanineamide (BzN-EJJ-amide). In HepG2 (human hepatoma cell line) cells, endogenous PTP1B was labeled by the UV-activated photoprobes in both lysed and intact cells. Enzyme occupancy measurements were conducted with a series of PTP1B inhibitors using the photoprobe affinity assay. Several compounds were shown to bind to endogenous PTP1B in the HepG2 intact cells.     

Allosteric inhibition of protein tyrosine phosphatase 1B

Obesity and type II diabetes are closely linked metabolic syndromes that afflict >100 million people worldwide. Although protein tyrosine phosphatase 1B (PTP1B) has emerged as a promising target for the treatment of both syndromes, the discovery of pharmaceutically acceptable inhibitors that bind at the active site remains a substantial challenge. Here we describe the discovery of an allosteric site in PTP1B. Crystal structures of PTP1B in complex with allosteric inhibitors reveal a novel site located approximately 20 A from the catalytic site. We show that allosteric inhibitors prevent formation of the active form of the enzyme by blocking mobility of the catalytic loop, thereby exploiting a general mechanism used by tyrosine phosphatases. Notably, these inhibitors exhibit selectivity for PTP1B and enhance insulin signaling in cells. Allosteric inhibition is a promising strategy for targeting PTP1B and constitutes a mechanism that may be applicable to other tyrosine phosphatases.     

Synthesis and characterization of 5,7-dihydroxyflavanone derivatives as novel protein tyrosine phosphatase 1B inhibitors

A series of 5,7-dihydroxyflavanone derivatives were synthesized and identified as reversible and competitive protein tyrosine phosphatase (PTP) 1B inhibitors with IC₅₀ values in the micromolar range. Compound 4k had the most potent in vitro inhibition activity against PTP1B (IC₅₀ = 2.37?±?0.37 μM) and the greatest selectivity (3.7-fold) for PTP1B relative to T-cell protein tyrosine phosphatase. Cell-based studies revealed that 4k was membrane-permeable and enhanced insulin receptor tyrosine phosphorylation in CHO/hIR cells.     

Rational design,synthesis, and structure–activity relationships of 5-amino-1H-pyrazole-4-carboxylic acid derivatives as protein tyrosine phosphatase 1B inhibitors

A series of novel amino-carboxylic based pyrazole as protein tyrosine phosphatase 1B (PTP1B) inhibitors were designed on the basis of structure-based pharmacophore model and molecular docking. Compounds containing different hydrophobic tail (1,2-diphenyl ethanone, oxdiadizole and dibenzyl amines) were synthesized and evaluated in PTP1B enzymatic assay. Structure–activity relationship based optimization resulted in identification of several potent, metabolically stable and cell permeable PTP1B inhibitors.     

Discovery of 1,3-diphenyl-1H-pyrazole derivatives containing rhodanine-3-alkanoic acid groups as potential PTP1B inhibitors

Two series of 1,3-diphenyl-1H-pyrazole derivatives containing rhodanine-3-alkanoic acid groups were identified as competitive protein tyrosine phosphatase 1B (PTP1B) inhibitors. Among the compounds studied, IIIv was found to have the best in vitro inhibition activity against PTP1B (IC₅₀?=?0.67?±?0.09?µM) and the best selectivity (9-fold) between PTP1B and T-cell protein tyrosine phosphatase (TCPTP). Molecular docking studies demonstrated that compounds IIIm, IIIv and IVg could occupy simultaneously at both the catalytic site and the adjacent pTyr binding site. These results provide novel lead compounds for the design of inhibitors of PTP1B as well as other PTPs.     

Benzothiazole benzimidazole (S)-isothiazolidinone derivatives as protein tyrosine phosphatase-1B inhibitors

Benzothiazole benzimidazole (S)-isothiazolidinone ((S)-IZD) derivatives 5 were discovered through a peptidomimetic modification of the tripeptide (S)-IZD protein tyrosine phosphatase 1B (PTP1B) inhibitor 1. These derivatives are potent, competitive, and reversible inhibitors of PTP1B with improved caco-2 permeability. An X-ray co-crystal structure of inhibitor 5/PTP1B at 2.2A resolution demonstrated that the benzothiazole benzimidazole forms bi-dentate H-bonds to Asp48, and the benzothiazole interacts with the surface of the protein in a solvent exposed region towards the C-site. The design, synthesis, and SAR of this novel series of benzothiazole benzimidazole containing (S)-IZD inhibitors of PTP1B are presented herein.     

Identification of novel imidazole flavonoids as potent and selective inhibitors of protein tyrosine phosphatase

A series of imidazole flavonoids as new type of protein tyrosine phosphatase inhibitors were synthesized and characterized. Most of them gave potent protein phosphatase 1B (PTP1B) inhibitory activities. Especially, compound 11a could effectively inhibit PTP1B with an IC₅₀ value of 0.63 μM accompanied with high selectivity ratio (9.5-fold) over T-cell protein tyrosine phosphatase (TCPTP). This compound is cell permeable with relatively low cytotoxicity. The high binding affinity and selectivity was disclosed by molecular modeling and dynamics studies. The structural features essential for activity were confirmed by quantum chemical studies.     

Fullerene derivatives as a new class of inhibitors of protein tyrosine phosphatases

In this study, we identified water-soluble C₆₀ and C₇₀ fullerene derivatives as a novel class of protein tyrosine phosphatase inhibitors. The evaluated compounds were found to inhibit CD45, PTP1B, TC-PTP, SHP2, and PTPβ with IC₅₀ values in the low micromolar to high nanomolar range. These results demonstrate a new strategy for designing effective nanoscale protein tyrosine phosphatase inhibitors.     

Investigation of selective binding of inhibitors to PTP1B and TCPTP by accelerated molecular dynamics simulations

Abstract

Protein tyrosine phosphatase 1B (PTP1B), a key negative regulator in insulin signaling pathways, is regarded as a potential target for the treatment of type II diabetes and obesity. However, the mechanism underlying the selectivity of PTP1B inhibitors against T-cell protein tyrosine phosphatase (TCPTP) remains controversial, which is due to the high similarity between PTP1B and TCPTP sequence and the fact that no ligand–protein complex of TCPTP has been established yet. Here, the accelerated molecular dynamics (aMD) method was used to investigate the structural dynamics of PTP1B and TCPTP that are bound by two chemically similar inhibitors with distinct selectivity. The conformational transitions during the “open” to “close” states of four complexes were captured, and free energy profiles of important residue pairs were analyzed in detail. Additional MM-PBSA calculations confirmed that the binding free energies of final states were consistent with the experimental results, and the energetic contributions of important residues were further investigated by alanine scanning mutagenesis. By comparing the four complexes, the different conformational behavior of WPD-loop, R-loop, and the second pTyr binding site induced by inhibitors were featured and found to be crucial for the selectivity of inhibitors. This study provides new mechanistic insights of specific binding of inhibitors to PTP1B and TCPTP, which can be exploited to the further structural-based inhibitor design.

Communicated by Ramaswamy H. Sarma     

PTP1B inhibitory activity of kaurane diterpenes isolated from Siegesbeckia glabrescens

Protein tyrosine phosphatase 1B (PTP1B) is considered as a therapeutic target for the treatment of diabetes and obesity. In our preliminary screening study, a MeOH extract of the aerial part of Siegesbeckia glabrescens was found to inhibit PTP1B activity at 30 microg/mL. Bioassay-guided fractionation led to the isolation of two active diterpenes, ent-16betaH, 17-isobutyryloxy-kauran-19-oic acid (1) and ent-16betaH, 17-acetoxy-18-isobutyryloxy-kauran-19-oic acid (2), along with ent- 16betaH, 17-hydroxykauran-19-oic acid (3). Compounds 1 and 2 inhibited the PTP1B activity with IC50 values of 8.7 +/- 0.9 and 30.6 +/- 2.1 microM, respectively. Kinetic studies suggest that both 1 and 2 are non-competitive inhibitors of PTP1B. However, compound 3 substituted with a hydroxyl group at C-17 in kaurane-type showed no inhibitory effects towards PTP1B.     

Design of specific inhibitors of the protein tyrosine phosphatase SHP-2 by virtual screening and core hopping method

The protein tyrosine phosphatase Src homology 2 (SH2) domain-containing phosphatase 2 (SHP-2) is an important signalling component of growth factors, cytokines and oncogenic bacteria. Studies have identified that gain-of-function SHP-2 mutations were associated with the Noonan syndrome, various kinds of leukaemias and solid tumours. However, it is complicated to find the specific inhibitors for SHP-2 over the closely related tyrosine phosphatase SHP-1 and protein tyrosine phosphatase 1B (PTP1B). The aim of this study was to develop potent and specific SHP-2 inhibitors as anticancer and antileukaemia agents. So the ZINC fragment database was searched for finding the optimal compound with the core hopping technique. As a result, the 15 compounds were obtained. It was observed by molecular dynamics simulations that those compounds interact with the active site of SHP-2 more strongly than with the corresponding sites of the closely related protein tyrosine phosphatases, SHP-1 and PTP1B. The ‘absorption, distribution, metabolism and excretion’ prediction shows that the 15 compounds may become candidates for developing powerful and novel drugs for treating Noonan syndrome, juvenile myelomonocytic leukaemia and possibly other SHP-2-associated cancers.     

2-Aryl-3,3,3-trifluoro-2-hydroxypropionic acids: a new class of protein tyrosine phosphatase 1B inhibitors

A new series of non-peptidic, mono-acid protein tyrosine phosphatase 1B (PTP1B) inhibitors has been identified by structure-based design. Compounds with 2-(indol-3-yl)- and 2-phenyl-3,3,3-trifluoro-2-hydroxypropionic acid core units targeted at the enzyme's primary site and a hydrophobic chlorophenylthiazole extension in its 2 degrees site exhibit 3-60microM IC(50)s for PTP1B inhibition in an Sf9 cell-based assay.     

Protein tyrosine phosphatase 1B inhibitors from Morus root bark

An organic layer prepared from the Chinese crude drug 'Sang-Bai-Pi' (Morus root bark) was studied in order to identify the inhibitory compounds for protein tyrosine phosphatase 1B (PTP1B). Bioassay-guided fractionation resulted in the isolation of sanggenon C (1), sanggenon G (2), mulberrofuran C (3) and kuwanon L (4) as PTP1B inhibitors, along with moracin O (5) and moracin P (6). Compounds 1-4 inhibited PTP1B with IC(50) values ranging from 1.6+/-0.3 microM to 16.9+/-1.1 microM.     

Inhibition of protein tyrosine phosphatase 1B by diterpenoids isolated from Acanthopanax koreanum

Inhibition of protein tyrosine phosphatase 1B (PTP1B) has been proposed as a therapy to treat type 2 diabetes and obesity. In our preliminary screening study on the PTP1B inhibitory activity, a CH2Cl2-soluble extract of the roots of Acanthopanax koreanum (Araliaceae) was found to inhibit PTP1B activity at 30 microg/ml. Eight diterpenoids were isolated from the active fraction and were evaluated for their inhibitory effect on PTP1B. A kaurane-type diterpene, 16alphaH,17-isovaleryloxy-ent-kauran-19-oic acid (7), inhibited PTP1B with an IC50 value of 7.1+/-0.9 microM in a non-competitive manner. Acanthoic acid (2) and ent-kaur-16-en-19-oic acid (5) also inhibited PTP1B in dose-dependent manners. Either introduction of a hydroxyl group or reduction of a carboxyl group at C-19 in pimarane-type to alcohol abolished the inhibitory effects toward PTP1B.     

Discovery and SAR of novel,potent and selective protein tyrosine phosphatase 1B inhibitors

A salicylate second site binder was linked to three classes of phosphotyrosine mimetics to produce potent protein tyrosine phosphatase 1B (PTP1B) inhibitors which exhibit significant selectivity against other phosphatases including the most homologous member, TCPTP.     

Dammaranes from Gynostemma pentaphyllum and synthesis of their derivatives as inhibitors of protein tyrosine phosphatase 1B

Protein tyrosine phosphatase 1B (PTP1B) is a key factor in the negative regulation of insulin pathway and a promising target for treatment of diabetes and obesity. Herein, the sapogenin 2b, prepared from the natural triterpene saponin 1b, was modified at 3-position to establish the dammarane derivatives library via esterification, oxidation and reductive amination reaction and evaluated as PTP1B inhibitors. 3-O-para-Carboxylphenyl substituted derivative 5b was found with the best in vitro inhibition activity to protein tyrosine phosphatase 1B (IC₅₀ = 0.27 μM), where 3-O-meta-carboxylphenyl substituted 5a exhibited the best selectivity (nearly fivefolds) between PTP1B and T-cell protein tyrosine phosphatase.