The Src homology-2 domain-containing phosphatase SHP-2 encoded by PTPN11 is an essential component in several signaling pathways.Different types of mutation in SHP-2 have been confirmed in several types of leukemia and solid tumors. Elucidation of the events underlying Shp2-evoked transformation may provide new insights into the novel targets for anti-cancer therapy.
Humans ; Protein Tyrosine Phosphatase, Non-Receptor Type 11 ; chemistry ; metabolism ; physiology

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

In order to express and purify the catalytic domain of SHP-1/SHP-2 (named as D1C and D2C respectively) and determine their kinetics, the constructed D1C and D2C plasmids were transformed into Escherichia coli BL21 and the expression was induced with IPTG. The harvested cells were suspended in extraction buffer. After sonication, the solution was applied to HPLC and the results were confirmed by SDS-PAGE. The purified peptides were further subjected to kinetic specificity study using synthetic phosphotyrosine (pY) as substrate by malachite green method and analyzed by Lineweaver-Burk plot calculation. From this study, we found D1C and D2C were expressed successfully in soluble state in Escherichia coli BL21 and purified efficiently with HPLC system. The molecular weight of D1C was 34.6 kD, and its Michaelis constant (K(m)) was 2.04 mmol catalytic constant (K(cat)) was 44.98 s(-1), specific constant (K(cat)/K(m)) was 22.05 L/(mmol x s); the molecular weigh of D2C was 35.3 kD, and its Michaelis constant (K(m)) was 2.47 mmol, catalytic constant (K(cat)) was 27.45 s(-1), specific constant (K(cat)/K(m)) was L/(mmol x s). The enzyme activity of D1C is stronger than that of D2C.
Catalytic Domain ; Chromatography, High Pressure Liquid ; Escherichia coli ; genetics ; metabolism ; Kinetics ; Plasmids ; Protein Tyrosine Phosphatase, Non-Receptor Type 11 ; genetics ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 6 ; genetics ; metabolism ; Recombinant Proteins ; genetics ; metabolism

More and more studies have found that the occurrence of tumors are directly related to the abnormal expression of oncogene and antioncogene. If the antioncogene is mutated or absent, the function of cells will be weakened and inactivated, the cells will be duplicated repeatedly out of control, then will induce occurrence and metastasis of tumor. For example, SHP-1 tyrosine phosphatase, as an antioncogene, is a key negative regulator in signaling transduction of haematopoietic cells. The decrease and silence of SHP-1 play an important role in tumorigenesis. If the oncogene in leukemia patients lost the effect of negative regulation of antioncogene, the oncogene would be expressed abnormally high, such as the oncogene c-kit (an important member of the class III in the tyrosine kinase receptor family) in many kinds of leukemia cells expresses actively. Studies have shown that the high methylation of promoter region would induce the inactivation of tumor suppressor and active expression of oncogene, therefore, the restoring normal methylation of promoter region will contribute to restoration of normal gene expression, thus achieving the purpose of gene therapy for leukemia. In this article, the methylation, methylation abnormality and leukemia, methylation suppressors and therapy of leukemia are briefly reviewed.
DNA Methylation ; drug effects ; Humans ; Leukemia ; drug therapy ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 6 ; 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

Animals ; Cell Proliferation ; Hepatic Stellate Cells ; Liver Cirrhosis/metabolism* ; Protein Tyrosine Phosphatase, Non-Receptor Type 6 ; Rats

CPTP1 is a nontransmembrane chicken protein tyrosine phosphatase having 92% sequence homology to the corresponding 321 amino acids of human protein tyrosine phosphatase 1B (HPTP1B). Using anti-CPTP1 antibody, we identified CPTP1-like rat PTP1 of 51 kappa Da in Rat-1 and v-src-transformed Rat-1 fibroblasts. Here we show that CPTP1-like rat PTP1 binds to p60v-src in vivo and CPTP1 also can associate with p60v-src in cell lysate of v-src- transformed Rat-1 fibroblasts. Interaction between HPTP1B-type PTPs, CPTP1-like rat PTP1 and CPTP1, and p60v-src was reduced by vanadate treatment for 13 h due to down regulation of the protein level of p60v-src in vivo. Interestingly, CPTP1-like rat PTP1 was coimmunoprecipitated with a 70-kappa Da protein which has a possibility to be tyrosine- phosphorylated by p60v-src in v-src-transformed Rat- 1 fibroblasts. These results suggest that HPTP1B- type PTPs may play an important role in p60src dependent signal pathway in eucaryotic cells.
Animals ; Blotting, Western ; Cell Line, Transformed ; Chickens ; Female ; Fibroblasts ; Oncogene Protein pp60(v-src)/*metabolism ; Phosphoprotein Phosphatase/genetics/*metabolism ; Precipitin Tests ; Protein Binding ; Protein-Tyrosine-Phosphatase/genetics/*metabolism ; Rabbits ; Rats ; Recombinant Fusion Proteins/genetics/metabolism

OBJECTIVETo investigate the role of cytoplasmic domain of integrin alpha IIb in platelet signal transduction.

METHODSBinding capacity of integrin alpha IIb(R995A) to antibody platelet activation complex-1 (PAC-1) and pp125 focal adhesion kinase (FAK) phosphorylation of cells were detected by flow cytometry, immune precipitation, and Western blotting.

RESULTSWithout activation, wild-type alpha IIb beta3 Chinese hamster ovary (CHO) cells failed to bind to PAC-1, but mutant chimera alpha IIb(R995A)beta3 CHO cells were able to bind with PAC-1. Furthermore, phosphorylation of pp125 (FAK) in wild-type alpha IIb beta3 CHO cells occured only when cells were adhered to fibrinogen, but could not be detected in bovine serum albumin suspension. However in the mutant chimera group, it could be detected in both conditions.

CONCLUSIONThe mutation in integrin alpha IIb(R995A) alters its affinity state as a receptor, thus also mediating cytoplasmic signal transduction leading to the phosphorylation of pp125 (FAK) without ligand binding.

Animals ; Blood Platelets ; metabolism ; CHO Cells ; Cell Adhesion ; Cricetinae ; Cricetulus ; Cytoplasm ; metabolism ; Dual Specificity Phosphatase 2 ; Focal Adhesion Kinase 1 ; Focal Adhesion Protein-Tyrosine Kinases ; Humans ; Phosphorylation ; Platelet Glycoprotein GPIIb-IIIa Complex ; genetics ; metabolism ; physiology ; Point Mutation ; Protein Phosphatase 2 ; Protein Tyrosine Phosphatases ; metabolism ; Protein-Tyrosine Kinases ; metabolism ; Signal Transduction ; Transfection

Reversible protein phosphorylation regulates multiple biochemical events. Mycobacterium tuberculosis phosphatases play important roles in regulating the pathogen physiology and interference of host signaling. They are also involved in the evasion of host immune response and blockage of the phagosome-lysosome fusion. Selective inhibition of phosphatase represents an ideal new avenue of anti-tuberculosis drug design. In this paper, we update the progresses about the regulation network of Mycobacterium tuberculosis phosphatases including MptpA, MptpB, MstP, SapM and their inhibitors. These serve as the basis for further antituberculosis drug target.
Acid Phosphatase ; antagonists & inhibitors ; metabolism ; Animals ; Antitubercular Agents ; pharmacology ; Bacterial Proteins ; antagonists & inhibitors ; metabolism ; Humans ; Mycobacterium tuberculosis ; drug effects ; enzymology ; Protein Tyrosine Phosphatases ; antagonists & inhibitors ; metabolism

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