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

OBJECTIVETo investigate the effects of protein tyrosine phosphatase-SHP2 and dual-specificity MAPK phosphatase-MKP5 on the activation of MAPKs and cell invasion induced by P2Y purinergic receptor in human prostate cancer cell lines with different metastatic potentials.

METHODSThe wide type (-wt) SHP2, mutant type (-cs) SHP2 and wide type (-wt) MKP5 cDNA expression vectors were constructed and stably transfected into 1E8 cells (highly metastatic) and/or 2B4 cells (non-metastatic). The tyrosine phosphorylation of SHP2 was examined by immunoprecipitation. The activation of ERK1/2 and p38 induced by P2Y receptor agonist ATP was analyzed by Western blot with phospho-specific antibodies against the dually phosphorylated, active forms of ERK1/2 and p38. The in-vitro invasive ability through Matrigel was measured by boyden-chamber assay.

RESULTSATP induced significant SHP2 phosphorylation, which was stronger and lasted longer in 1E8 than in 2B4. SHP2-wt enhanced the ERK1/2 activation induced by ATP in 2B4 cells, while SHP2-cs delayed and decreased this effect in 1E8 cells. Both SHP2-wt and SHP2-cs had no obvious influence on p38 activation. ATP stimulated cell invasion of both 1E8 and 2B4, while transfection of SHP2-wt into 2B4 cells further increased the invasive-stimulating ability of ATP (18.7% increase compared with ATP treatment alone). Transfection of SHP2-cs into 1E8 cells, however, antagonized the invasive-stimulating ability of ATP (40.9% decrease compared with ATP treated group). Up-regulation of MKP5-wt inhibited phosphorylation of p38 by ATP and reduced cell invasion stimulated by ATP (22.4% and 28.7% decrease compared with ATP treated group of 1E8 and 2B4, respectively).

CONCLUSIONSBoth SHP2 and MKP5 play some roles in P2Y receptor-mediated activation of MEK/ERK, p38 signaling pathways and prostate cancer invasion. SHP2 positively regulates ERK activation and prostate cancer invasion, whereas MKP5 inhibits the invasion by suppressing p38 activation.

Adenosine Triphosphate ; pharmacology ; Cell Line, Tumor ; DNA, Complementary ; genetics ; Dual-Specificity Phosphatases ; Genetic Vectors ; Humans ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Male ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Mitogen-Activated Protein Kinase Phosphatases ; Neoplasm Invasiveness ; Phosphorylation ; Prostatic Neoplasms ; metabolism ; pathology ; Protein Tyrosine Phosphatase, Non-Receptor Type 11 ; Protein Tyrosine Phosphatases ; genetics ; metabolism ; Receptors, Purinergic P2 ; physiology ; Signal Transduction ; Transfection ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo explore the expression of tyrosine phosphatase containing C-src homology SH-2 (SHP-1 and SHP-2) in benign prostate hyperplasia.

METHODSWith En Vision two-step method, the expression of SHP-1 and SHP-2 was detected in 10 cases of normal prostate tissue, 30 cases of BPH, 20 cases of PIN, 20 cases of high differential Pca and 20 cases of low differential Pca.

RESULTThe expression of SHP-2 in normal group was mainly distributed in the cytoplasm of secretive cells and basal cells, and a little part in the nucleu. In BPH it was distributed equally in the plasm and nucleu. In PIN, high differential Pca and low differential Pca, SHP-2 expressed mainly in nucleu. The average dyeing index of SHP-2 in each group is 0.4, 1.7, 2.1, 2.2 and 2.6. SHP-1 positive expression in normal prostate, BPH, PIN and high differential Pca showed differentiating layer staining in the cytoplasm of secretive cells and basal cells, while not in low differential Pca. The average dyeing index of SHP-1 in each group is 1.8, 1.8, 1.5, 1.2 and 0.4.

CONCLUSIONThere are transformation in signal transduction relation with SHP-1 and SHP-2 in the progress of prostate cell proliferation, differentiation and malignant. The abnormal activation and distribution of SHP-2 might induce prostate reconstruction and hyperplasia, even carcinoma.

Adult ; Aged ; Cell Nucleus ; enzymology ; Cytoplasm ; enzymology ; Humans ; Immunohistochemistry ; Male ; Middle Aged ; Prostatic Hyperplasia ; enzymology ; pathology ; Protein Tyrosine Phosphatase, Non-Receptor Type 11 ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 6 ; metabolism ; Protein Tyrosine Phosphatases ; metabolism ; SH2 Domain-Containing Protein Tyrosine Phosphatases ; metabolism ; src-Family Kinases ; metabolism

Protein tyrosine phosphatases (PTPs) are key regulatory factors in inflammatory signaling pathways. Although PTPs have been extensively studied, little is known about their role in neuroinflammation. In the present study, we examined the expression of 6 different PTPs (PTP1B, TC-PTP, SHP2, MEG2, LYP, and RPTPβ) and their role in glial activation and neuroinflammation. All PTPs were expressed in brain and glia. The expression of PTP1B, SHP2, and LYP was enhanced in the inflamed brain. The expression of PTP1B, TC-PTP, and LYP was increased after treating microglia cells with lipopolysaccharide (LPS). To examine the role of PTPs in microglial activation and neuroinflammation, we used specific pharmacological inhibitors of PTPs. Inhibition of PTP1B, TC-PTP, SHP2, LYP, and RPTPβ suppressed nitric oxide production in LPS-treated microglial cells in a dose-dependent manner. Furthermore, intracerebroventricular injection of PTP1B, TC-PTP, SHP2, and RPTPβ inhibitors downregulated microglial activation in an LPS-induced neuroinflammation model. Our results indicate that multiple PTPs are involved in regulating microglial activation and neuroinflammation, with different expression patterns and specific functions. Thus, PTP inhibitors can be exploited for therapeutic modulation of microglial activation in neuroinflammatory diseases.
Brain ; Microglia ; Neuroglia ; Nitric Oxide ; Protein Tyrosine Phosphatase, Non-Receptor Type 2 ; Protein Tyrosine Phosphatases*

The hematopoietic cell phosphatase (HCP or SHP-1), the SH2 domain contain protein tyrosine phosphatase, is a crucial negative regulator in the process of hematopoietic cell development, proliferation and receptor-mediated mitogenic signaling pathways, and its mutation is responsible for the over-expansion and inappropriate activation of myelomonocytic population in motheaten mice. The aim of the study was to evaluate the role of the HCP gene in leukemogenesis. Bone marrow and/or peripheral blood from 32 acute myeloid leukemia (AML) patients, 9 acute lymphocytic leukemia (ALL) patients, 8 leukemia cell lines and 50 normal controls were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) based on single strand conformation polymorphism (SSCP) and sequencing. RT-PCR showed that all samples expressed HCP gene, only one missense mutation at codon 225 (AAC to AGC, Asn to Ser) within N-terminal SH2 domain was found in an ALL patient. In addition, four polymorphic base substitutions were detected in codon 69, 85, 86 and 266, respectively. In conclusion, mutation of HCP gene is an infrequent genetic aberration which may only play a role in pathogenesis of a small part of leukemia, however, its significance needs to be further clarified.
Acute Disease ; Cell Line, Tumor ; Humans ; Intracellular Signaling Peptides and Proteins ; Leukemia ; enzymology ; genetics ; Mutation ; Polymorphism, Single-Stranded Conformational ; Protein Tyrosine Phosphatase, Non-Receptor Type 6 ; Protein Tyrosine Phosphatases ; genetics

Cyclic ADP-ribose (cADPR) releases Ca²⁺ from ryanodine receptor (RyR)-sensitive calcium pools in various cell types. In cardiac myocytes, the physiological levels of cADPR transiently increase the amplitude and frequency of Ca²⁺ (that is, a rapid increase and decrease of calcium within one second) during the cardiac action potential. In this study, we demonstrated that cADPR levels higher than physiological levels induce a slow and gradual increase in the resting intracellular Ca²⁺ ([Ca²⁺](i)) level over 10 min by inhibiting the sarcoendoplasmic reticulum Ca²⁺ ATPase (SERCA). Higher cADPR levels mediate the tyrosine-dephosphorylation of α-actin by protein tyrosine phosphatase 1B (PTP1B) present in the endoplasmic reticulum. The tyrosine dephosphorylation of α-actin dissociates phospholamban, the key regulator of SERCA, from α-actin and results in SERCA inhibition. The disruption of the integrity of α-actin by cytochalasin B and the inhibition of α-actin tyrosine dephosphorylation by a PTP1B inhibitor block cADPR-mediated Ca²⁺ increase. Our results suggest that levels of cADPR that are relatively higher than normal physiological levels modify calcium homeostasis through the dephosphorylation of α-actin by PTB1B and the subsequent inhibition of SERCA in cardiac myocytes.
Action Potentials ; Adenosine Diphosphate* ; Adenosine Triphosphatases ; Calcium ; Cyclic ADP-Ribose ; Cytochalasin B ; Endoplasmic Reticulum ; Homeostasis ; Muscle Cells* ; Myocytes, Cardiac ; Protein Tyrosine Phosphatase, Non-Receptor Type 1* ; Protein Tyrosine Phosphatases* ; Reticulum ; Ryanodine Receptor Calcium Release Channel ; Tyrosine

OBJECTIVESTo obtain prokaryotic expressed IA-2 recombinant protein and to identify its immunological activity.

METHODSThe complimentary DNA (cDNA) coding for the intracytoplasmic part of IA-2 (IA-2ic) was amplified from human fetal brain RNA, and was subcloned into the PinPoint Xa-1 T vector to construct recombinant expression plasmid, and was then expressed in E. coli JM109 cells as a fusion protein with a biotinylated peptide sequence at the aminoterminus. The biotinylated fusion protein was then purified by affinity chromatography and was subsequently dialyzed. Finally, its immunogenicity was evaluated by enzyme linked immunosorbent assay (ELISA).

RESULTSThe purified IA-2ic fusion protein resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as a single Coomassie brilliant blue stained band with a molecular weight of 59 kDa and its immunogenicity was confirmed by ELISA.

CONCLUSIONSE. coli expressed IA-2ic fusion protein has immunological activity. It can be used for detection of IA-2 autoantibodies (IA-2A) and for further studies on type 1 diabetes in future.

Animals ; Autoantigens ; biosynthesis ; DNA, Complementary ; analysis ; Diabetes Mellitus, Type 1 ; immunology ; Escherichia coli ; genetics ; Humans ; Membrane Proteins ; biosynthesis ; genetics ; isolation & purification ; Plasmids ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; Protein Tyrosine Phosphatases ; biosynthesis ; genetics ; isolation & purification ; Rabbits ; Receptor-Like Protein Tyrosine Phosphatases, Class 8 ; Recombinant Fusion Proteins ; biosynthesis ; immunology ; isolation & purification

Animals ; Animals, Newborn ; Brain ; blood supply ; metabolism ; pathology ; Carrier Proteins ; genetics ; DNA-(Apurinic or Apyrimidinic Site) Lyase ; genetics ; Gene Expression ; Hypoxia-Ischemia, Brain ; genetics ; pathology ; In Situ Hybridization ; Protein Tyrosine Phosphatase, Non-Receptor Type 13 ; Protein Tyrosine Phosphatases ; genetics ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Wistar

Protein tyrosine phosphatase 1B (PTP1B) has led to an intense interest in developing its inhibitors as anti-diabetes, anti-obesity and anti-cancer agents. The fruits of Rubus chingii (Chinese raspberry) were used as a kind of dietary traditional Chinese medicine. The methanolic extract of R. chingii fruits exhibited significant PTP1B inhibitory activity. Further bioactivity-guided fractionation resulted in the isolation of three PTP1B inhibitory ursane-type triterpenes: ursolic acid (1), 2-oxopomolic acid (2), and 2α, 19α-dihydroxy-3-oxo-urs-12-en-28-oic acid (3). Kinetics analyses revealed that 1 was a non-competitive PTP1B inhibitor, and 2 and 3 were mixed type PTP1B inhibitors. Compounds 1-3 and structurally related triterpenes (4-8) were further analyzed the structure-activity relationship, and were evaluated the inhibitory selectivity against four homologous protein tyrosine phosphatases (TCPTP, VHR, SHP-1 and SHP-2). Molecular docking simulations were also carried out, and the result indicated that 1, 3-acetoxy-urs-12-ene-28-oic acid (5), and pomolic acid-3β-acetate (6) bound at the allosteric site including α3, α6, and α7 helix of PTP1B.
Enzyme Inhibitors ; chemistry ; metabolism ; Fruit ; chemistry ; Humans ; Kinetics ; Methanol ; chemistry ; Molecular Docking Simulation ; Molecular Structure ; Plant Extracts ; chemistry ; Protein Binding ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; antagonists & inhibitors ; metabolism ; Protein Tyrosine Phosphatases ; antagonists & inhibitors ; Rubus ; chemistry ; Structure-Activity Relationship ; Triterpenes ; chemistry ; metabolism

BACKGROUNDChina is one of the countries with the highest incidence of H. pylori and more than 9090 isolates possessed the cagA gene. This study was to evaluate the biological activity of the H. pylori virulence factor cagA isolated from Chinese patients.

METHODScagA DNA fragments were amplified from the genomic DNA and subsequently cloned into the mammalian expression vector for cell transfection and DNA sequencing. cagA protein, phosphorylated-tyrosine cagA and the complex of cagA precipitated with SHP-2 were identified respectively by western blot in the crude cell lysate from conditionally immortalized gastric epithelial cells at 48 hours after transfection with cagA DNA. In addition, the ability of induction of scattering phenotype was examined after transient expression of cagA in AGS cells.

RESULTSThe C-terminal half of cagA contained only one repeated sequence and three tandem five-amino-acid motifs glutamic acid-proline-isoleucine-tyrosine-alanine (EPIYA). Moreover, the amino acid sequence of D2 region in repeated sequence was aspartic acid-phenylanaline-aspartic acid (D-F-D) which was significantly distinguished from the three repeated sequences and aspartic acid-aspartic adid-leucine (D-D-L) in the western standard strain NCTC11637. Western blot revealed that cagA became phosphorylated in tyrosine site and bound with SHP-2 after transient expression of cagA DNA in gastric epithelial cells. Transient expression of cagA in AGS cells showed that cagA was able to induce the elongation phenotype although to a lesser extent than western strains.

CONCLUSIONScagA perturbs cell signaling pathways by binding with SHP-2. However, significant difference exists in amino acid sequence and biological function of cagA in Chinese compared with those of western countries.

Amino Acid Sequence ; Antigens, Bacterial ; chemistry ; physiology ; Bacterial Proteins ; chemistry ; physiology ; Blotting, Western ; Cells, Cultured ; Gastric Mucosa ; Humans ; Intracellular Signaling Peptides and Proteins ; Molecular Sequence Data ; Phenotype ; Phosphorylation ; Protein Tyrosine Phosphatase, Non-Receptor Type 11 ; Protein Tyrosine Phosphatases ; metabolism ; Repetitive Sequences, Amino Acid ; Signal Transduction