Protein tyrosine phosphatase (PTP) 1B is a potential target for the treatment of diabetes and obesity. We have previously identified the benzoyl sulfathiazole derivative II as a non-competitive PTP1B inhibitor with in vivo insulin sensitizing effects. Preliminary SAR study on this compound series has been carried out herein, and thirteen new compounds have been designed and synthesized. Among them, compound 10 exhibited potent inhibition against human recombinant PTP1B with the IC50 value of 3.97 micromol x L(-1), and is comparable to that of compound II.
Humans ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; antagonists & inhibitors ; Structure-Activity Relationship ; Sulfathiazoles ; chemistry ; pharmacology

OBJECTIVETo synthesize (2'-bromo-4',5'-dimethoxy-phenyl)-( 2,3- dibromo-4,5-dimethoxy-phenyl)-methane (6) as protein tyrosine phosphatase 1B (PTP1B) inhibitor.

METHODCompound 6 was synthesized by Friedel-Crafts reaction, bromination and decarbonylation and screened inhibitory activity against PTP1B by the colorimetric assay. The structure of synthetic intermediates and target product were identified on the basis of spectral analysis.

RESULTCompound 6 was synthesized successfully in four steps and evaluated for its PTP1B inhibitory activity, the screening result shown that compound 6 displayed good inhibitory activity against PTP1B.

CONCLUSIONThe target compound 6 was synthesized with the overall yield of 20%, which was a new compound and shown good inhibitory activity against PTP1B (inhibition 40.16% at 5 mg x L(-1)).

Enzyme Inhibitors ; chemical synthesis ; chemistry ; Kinetics ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; antagonists & inhibitors

The influences of specific protein phosphatase and protein kinase inhibitors on the ATP-sensitive K+ (KATP) channel-opening effect of pinacidil were investigated in single rat ventricular myocytes using patch clamp technique. In cell-attached patches, pinacidil (100 muM) induced the opening of the KATP channel, which was blocked by the pretreatment with H-7 (100 muM) whereas enhanced by the pretreatment with genistein (30 muM) or tyrphostin A23 (10 muM). In inside-out patches, pinacidil (10 muM) activated the KATP channels in the presence of ATP (0.3 mM) or AMP-PNP (0.3 mM) and in a partial rundown state. The effect of pinacidil (10 muM) was not affected by the pretreatment with protein tyrosine phosphatase 1B (PTP1B, 10 mug ml-1), but blocked by the pretreatment of protein phosphatase 2A (PP2A, 1 U ml-1). In addition, pinacidil (10 muM) could not induce the opening of the reactivated KATP channels in the presence of H-7 (100 muM) but enhanced it in the presence of ATP(1 mM) and genistein (30 muM). These results indicate that the KATP channel-opening effect of pinacidil is not mediated via phosphorylation of KATP channel protein or associated protein, although it still requires the phosphorylation of serine/threonine residues as a prerequisite condition.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine ; Adenosine Triphosphate ; Adenylyl Imidodiphosphate ; Animals ; Genistein ; KATP Channels ; Muscle Cells* ; Phosphorylation* ; Pinacidil* ; Protein Kinase Inhibitors ; Protein Phosphatase 2 ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; Rats*

Chronic (>24 h) exposure of arsenite, an environmental toxicant, has shown the decreased nitric oxide (NO) production in endothelial cells (EC) by decreasing endothelial NO synthase (eNOS) expression and/or its phosphorylation at serine 1179 (eNOS-Ser1179 in bovine sequence), which is associated with increased risk of vascular diseases. Here, we investigated the acute (<24 h) effect of arsenite on NO production using bovine aortic EC (BAEC). Arsenite acutely increased the phosphorylation of eNOS-Thr497, but not of eNOS-Ser116 or eNOS-Ser1179, which was accompanied by decreased NO production. The level of eNOS expression was unaltered under this condition. Treatment with arsenite also induced reactive oxygen species (ROS) production, and pretreatment with a ROS scavenger N-acetyl-L-cysteine (NAC) completely reversed the observed effect of arsenite on eNOS-Thr497 phosphorylation. Although protein kinase C (PKC) and protein phosphatase 1 (PP1) were reported to be involved in eNOS-Thr497 phosphorylation, treatment with PKC inhibitor, Ro318425, and overexpression of various PKC isoforms did not affect the arsenite-stimulated eNOS-Thr497 phosphorylation. In contrast, treatment with PP1 inhibitor, calyculin A, mimicked the observed effect of arsenite on eNOS-Thr497 phosphorylation. Lastly, we found decreased cellular PP1 activity in arsenite-treated cells, which was reversed by NAC. Overall, our study demonstrates firstly that arsenite acutely decreases NO production at least in part by increasing eNOS-Thr497 phosphorylation via ROS-PP1 signaling pathway, which provide the molecular mechanism underlying arsenite-induced increase in vascular disease.
Acetylcysteine ; Endothelial Cells ; Nitric Oxide Synthase ; Nitric Oxide Synthase Type III ; Nitric Oxide* ; Phosphorylation ; Protein Isoforms ; Protein Kinase C ; Protein Phosphatase 1 ; Reactive Oxygen Species ; Serine ; Vascular Diseases

Protein phosphatase 1 (PP1) is involved in various signal transduction mechanisms as an extensive regulator. The PP1 catalytic subunit (PP1c) recognizes and binds to PP1-binding consensus residues (FxxR/KxR/K) in NBCe1-B. Consequently, we focused on identifying the function of the PP1-binding consensus residue, ⁹²²FMDRLK⁹²⁷ , in NBCe1-B. Using site-directed mutagenesis and co-immunoprecipitation assays, we revealed that in cases where the residues were substituted (F922A, R925A, and K927A) or deleted (deletion of amino acids 922–927), NBCe1-B mutants inhibited PP1 binding to NBCe1-B. Additionally, by recording the intracellular pH, we found that PP1-binding consensus residues in NBCe1-B were not only critical for NBCe1-B activity, but also relevant to its surface expression level. Therefore, we reported that NBCe1-B, as a substrate of PP1, contains these residues in the C-terminal region and that the direct interaction between NBCe1-B and PP1 is functionally critical in controlling the regulation of the HCO₃⁻ transport. These results suggested that like IRBIT, PP1 was another novel regulator of HCO₃⁻ secretion in several types of epithelia.
Amino Acids ; Catalytic Domain ; Consensus* ; Hydrogen-Ion Concentration ; Immunoprecipitation ; Mutagenesis, Site-Directed ; Protein Phosphatase 1 ; Signal Transduction

Diabetes mellitus is caused by deficiency of insulin secretion from the pancreatic islet beta cells and/or insulin resistance in liver, muscle and adipocytes, resulting in glucose intolerance and hyperglycemia. Several protein tyrosine phosphatases, such as PTP1B (PTPN1), TCPTP (PTPN2), LYP (PTPN22), PTPIA-2, PTPMEG2 (PTPN9) or OSTPTP are involved in insulin signaling pathway, insulin secretion and autoreactive attack to pancreatic beta cells. Genetic mutation or overexpression of these phosphotases has been found to cause or increase the risk of diabetes mellitus. Some population with high risk for type 2 diabetes has overexpressed PTP1B, a prototypical tyrosine phosphatase which down-regulates insulin and leptin signal transduction. Animal PTP1B knockout model and PTP1B specific inhibitor cellular studies indicate PTP1B may serve as a therapeutic target for type 2 diabetes. TCPTP shares more than 70% sequence identity with PTP1B in their catalytic domain. TCPTP dephosphorylates tyrosine phosphorylated substrates overlapping with PTP1B but also has its own distinct dephosphorylation sites and functions. Recent research indicates TCPTP may have role in type 1 diabetes via dysregultaion of cytokine-mediated immune responses or pancreatic beta cell apoptosis. The tyrosine phosphatase LYP, which down-regulates LCK activity in T cell response, can become mutated as R620W which is highly correlated to type 1 diabetes. LYP R620W may be a gain of function mutation which suppresses TCR signaling. Patients bearing the R620W mutant have impaired T cell responses and increased populations of (CD45RO+CD45RA-) CD4+ T cells. A detailed elucidation of mechanism of R620W in type 1 diabetes and specific LYP inhibitor development will help characterize LYP R620W as a therapeutic target. A receptor tyrosine phosphatase, PTPIA-2/beta is a major autoantigen of type 1 diabetes. A diagnosis kit identifying PTPIA-2/beta autoantibodies is valuable in early detection and prevention of type 1 diabetes. In addition, other phosphatase like OSTPTP and PTPMEG2 are involved in type 2 diabetes via regulation of insulin production, beta cell growth or insulin signaling. Research into understanding the mechanism of these tyrosine phosphatases in diabetes, such as their precise functions in the regulation of insulin secretion, the insulin response and the immune response will strengthen our knowledge of diabetes pathophysiology which may result in new diagnostic and therapeutic strategies for diabetes.
Animals ; Diabetes Mellitus ; enzymology ; Diabetes Mellitus, Type 1 ; enzymology ; Diabetes Mellitus, Type 2 ; enzymology ; Humans ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; genetics ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 2 ; genetics ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 22 ; genetics ; metabolism ; Protein Tyrosine Phosphatases, Non-Receptor ; classification ; genetics ; metabolism

OBJECTIVE: To investigate the relationship between polymorphism in interleukin-1 receptor antagonist (IL-1ra) gene and bone mineral density (BMD) in postmenopausal Korean women. METHODS: The 86-base pair repeat polymorphism in the IL-1ra gene was examined by polymerase chain reaction (PCR) and electrophoresis in 285 postmenopausal Korean women. Serum bone alkaline phosphatase (BAP) and CrossLaps (CTX) were measured by immunoassay and BMD at the lumbar spine and proximal femur by dual energy X-ray absorptiometry. RESULTS: Four alleles in IL-1ra gene were identified; A1 (4 repeats), A2 (2 repeats), A3 (5 repeats), A4 (3 repeats). BMD at the lumbar spine, femoral neck, and trochanter in women carrying A2 allele was significantly lower, compared with noncarriage of that allele. Serum BAP levels in the former group were higher than those in the latter group, but no difference in serum CTX levels between two groups was observed. There were no differences in the distribution of IL-1ra A2 allele among normal, osteopenic, and osteoporotic postmenopausal women. CONCLUSIONS: BMD are associated with a polymorphism in IL-1ra gene in postmenopausal Korean women.
Absorptiometry, Photon ; Alkaline Phosphatase ; Alleles ; Bone Density* ; Electrophoresis ; Female ; Femur ; Femur Neck ; Humans ; Immunoassay ; Interleukin 1 Receptor Antagonist Protein ; Interleukin-1* ; Polymerase Chain Reaction ; Spine

protein 3, epidermal growth factor receptor pathway substrate 15, transcription factor CP2, CDC20 cell division cycle 20 homolog, BRCA1 associated protein, and glutaminase were increased their expression after the administration of FGF-5. The pinin, ribosomal protein S29, proliferation-associated 2G4, protein phosphatase 1G, PICTAIRE protein kinase 1, cell division cycle 25A, keratin 7, 15, and 17, bone morphogenetic protein 1 and 7, and placental growth factor were In conclusion, FGF-5 was a potent mitogen for human fibroblasts, but FGF-7 was not. FGF-5 could induce FGF-7 expression, but FGF-7 inhibited FGF-5 expression. Thus, the gingival hyperplasia in the immunosuppressed patients seemed to be occurred via the action of FGF-5. The role of FGF-7 that was expressed in these patients might be late events after the expression of FGF-5.]]>
Bone Morphogenetic Protein 1 ; Carrier Proteins ; Cell Count ; Cell Cycle ; DNA, Complementary ; Fibroblasts ; Gingival Hyperplasia ; Glutaminase ; Humans ; Keratin-7 ; Oligonucleotide Array Sequence Analysis ; Organ Transplantation ; Protein Kinases ; Protein Phosphatase 1 ; Receptor, Epidermal Growth Factor ; Ribosomal Proteins ; Transcription Factors ; Transplants

OBJECTIVETo explore if the hypoxia/reoxygenation-induced increased activity and expression of PTP-1B in neonatal rat cardiomyocytes are mediated by nitric oxide (NO).

METHODSNeonatal rat cardiomyocytes were isolated and randomly divided into 4 groups: normal group (N group); hypoxia/reoxygenation group (H/R group); N(omega)-nitro-l-arginine methylester treated group (L-NAME group); hypoxia/reoxygenation plus L-NAME group (L-NA + H/R group). PTP-1B activity in cardiomyocytes was determined spectrophotometrically at 405 nm, PTP-1B expression in cardiomyocytes was detected by Western blot.NO and LDH concentrations in cell medium were also assayed.

RESULTSPTP-1B activity and expression in cardiomyocytes was significantly higher in the H/R group as compared to the N group and this increase could be blocked by cotreatment with L-NAME. As compared to H/R group, nitric oxide and LDH concentrations in cell medium were significantly decreased in the L-NA + H/R group (NO concentration: H/R group, 368% +/- 13% and L-NA + H/R group, 61% +/- 7%, P < 0.005; LDH concentration: H/R group, 41.2 +/- 6.7 and L-NA + H/R group, 23.6 +/- 4.8, P < 0.05).

CONCLUSIONSThis study showed that pretreatment with L-NAME, a non-selective inhibitor of NOS, prevented the hypoxia/reoxygenation-induced increase in PTP-1B activity and expression in cardiomyocytes, suggesting PTP-1B activation during hypoxia/reoxygenation was mediated by nitric oxide.

Animals ; Cell Hypoxia ; Cells, Cultured ; Myocytes, Cardiac ; cytology ; metabolism ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; metabolism ; Rats

OBJECTIVETo study the protein tyrosine phosphatase-1B (PTP1B) inhibitory activity of natural products from algae aiming at searching for new way for the treatment of type 2 diabetes mellitus (T2DM) and obesity.

METHODBromophenols derivatives from algae were screened against the PTP1B by the colorimetric assay with GST/PTP1B fusion protein. The Me2SO was distributed as the full enzyme activity, and Na3VO4 (IC50 2 micromol L(-1)) was distributed as the positive control. Inhibition rate was assayed and IC50 were calculated by LOGIT method.

RESULTThree bromophenols from Rhodomela confervoides and Leathesia nana, 3, 4-dibromo-5-(methoxymethyl)-1, 2-benzenediol (1), 2-methyl-3-(2, 3-dibromo4, 5-dihydroxy)-propylaldehyde (2) and 3-(2, 3-dibromo-4, 5-dihydroxy-phenyl)-4-bromo-5, 6-dihydroxy-1, 3-dihydroiso-benzofuran (3) showed significant inhibitory activity against PTP1B. IC50 values were 3.4 +/- micromol L(-1), 4.5 micromol L(-1) and 2.8 micromol L(-1), respectively.

CONCLUSIONThe results prove that three bromophenol derivatives from algae with significant inhibitory activity against PTP1B were potential and effective therapeutic agents for treatment of T2DM and obesity.

Diabetes Mellitus, Type 2 ; drug therapy ; metabolism ; Eukaryota ; chemistry ; Phaeophyta ; chemistry ; Phenols ; chemistry ; therapeutic use ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; antagonists & inhibitors ; Rhodophyta ; chemistry