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*

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 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

OBJECTIVETo investigate the expression of protein tyrosine phosphatase non-receptor type 2 (PTPN2) and nuclear factor-kappaB (NF-kappaB), as well as the relationship between their expression and periodontal destruction in mice with diabetic periodontitis.

METHODSFour weeks old healthy C57BL/6J mice were randomly divided into normal control group (Group N), periodontitis group (Group P) and diabetic periodontitis group (Group DP), and each group had six mice. Mice in Group P were inoculated Porphyromonas gingivalis orally to induce periodontitis. Mice in Group DP had high sugary and fatty food, streptozotocin intraperitoneal injection and Porphyromonas gingivalis oral inoculation to induce diabetic periodontitis. All mice were sacrificed 4 weeks after the last bacterium inoculation of Groups P and DP. Stereo microscope was chosen to detect morphological changes and bone loss areas of the alveolar bone. Hematoxylin-eosin (HE) staining was selected to observe loss heights of periodontal attachment. Immunohistochemical staining was used to detect PTPN2 and NF-kappaB expression in periodontal tissues.

RESULTSGroup P and Group DP had significantly more attachment loss heights and areas than Group N (P < 0.05), and showed less PTPN2 expression (P < 0.05) and higher NF-kappaB levels (P < 0.01).

CONCLUSIONPTPN2 may negatively regulate the development of diabetic periodontitis, while NF-kappaB may have opposite effects. PTPN2 down-regulation might contribute to NF-kappaB over-expression leading to exacerbated periodontal destruction.

Alveolar Bone Loss ; Animals ; Diabetes Mellitus ; Mice ; Mice, Inbred C57BL ; NF-kappa B ; Periodontitis ; Porphyromonas gingivalis ; Protein Tyrosine Phosphatase, Non-Receptor Type 2

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*

Rheumatoid arthritis (RA) is a chronic, inflammatory, autoimmune disorder that principally attacks flexible joints and synovia. The precise pathogenesis of RA remains unclear, and genetic factors probably play an important role in its etiology. In addition to genes from human leukocyte antigen (HLA) region, such as HLA-DRB, genes from non-HLA region, such as TIM-3, PTPN22, TRAF1/C5, STAT4, CCR5, PADI4 and FCGR2A may also contribute to its susceptibility. The advance in molecular genetics research on RA is reviewed here.
Arthritis, Rheumatoid ; genetics ; Exome ; Genetic Predisposition to Disease ; HLA-DRB1 Chains ; genetics ; Hepatitis A Virus Cellular Receptor 2 ; Humans ; Membrane Proteins ; genetics ; Protein Tyrosine Phosphatase, Non-Receptor Type 22 ; genetics ; Receptors, IgG ; genetics

OBJECTIVETo investigate the profile of promoter methylation and expression of SHP-1 gene in the progression of chronic myeloid leukemia (CML).

METHODSThe expression level of SHP-1 mRNA and protein in bone marrow or peripheral blood mononuclear cells from CML patients were detected by Western blot and SYBR Green-based qRT-PCR. The methylation status of SHP-1 were assessed by methylation-specific polymerase chain reaction (MSP) assay. K562 cells were infected with the lentiviral plasmids pEX-SHP-1-puro-Lv105 (K562-SHP-1) or pEX-EGFP-puro-Lv105 (K562-EGFP). The levels of proteins and phosphorylated proteins were detected by Western blot. qRT-PCR assay was used to test the level of BCR-ABL mRNA.

RESULTSThe relative levels of SHP-1 mRNA were sharply decreased in advanced stages CML compared to chronic phase (CP)-CML (0.79±0.37 vs 1.18±0.64, P= 0.009). The level of SHP-1 protein was lower in advanced stages CML compared to CP-CML (0.57±0.02 vs 1.02±0.04, P=0.039). The frequency of SHP-1 gene promoter methylation at selected loci in CP-CML was 23.8% (10/42), and the methylated regions were detected in all advanced CML samples (P<0.01). SHP-1 was stably transfected into K562 cells and selected with puromycin. Overexpression of SHP-1 inhibited the proliferation and induced the apoptosis of K562 cells, meanwhile leaded to G0/G1 phase arrest. After transfection, the level of BCR-ABL mRNA was not affected in K562-SHP-1 cells (1.32±0.34) compared to K562-EGFP cells (1.18±0.20, P=0.644), but overexpression of SHP-1 caused a slight decrease in BCR-ABL protein in K562-SHP-1 cells compared to K562 -EGFP cells (0.78±0.15 vs 1.27±0.24, P=0.040). Overexpression of SHP-1 resulted in a remarkable decrease in MYC protein, phosphorylated forms of JAK2, STAT5, Akt and MAPK. However, the un-phosphorylated forms of these molecules were not significantly affected.

CONCLUSIONDecreased expression of SHP-1 caused by aberrant promoter hypermethylation may play a key role in the progression of CML by dysregulation of BCR-ABL, Akt, MAPK, MYC, JAK2 and STAT5 signaling.

Apoptosis ; DNA Methylation ; Disease Progression ; Fusion Proteins, bcr-abl ; Humans ; Janus Kinase 2 ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; Leukocytes, Mononuclear ; Phosphorylation ; Protein Tyrosine Phosphatase, Non-Receptor Type 6 ; RNA, Messenger

Thyroid diseases, including autoimmune thyroid diseases and thyroid cancer, are known to have high heritability. Family and twin studies have indicated that genetics plays a major role in the development of thyroid diseases. Thyroid function, represented by thyroid stimulating hormone (TSH) and free thyroxine (T4), is also known to be partly genetically determined. Before the era of genome-wide association studies (GWAS), the ability to identify genes responsible for susceptibility to thyroid disease was limited. Over the past decade, GWAS have been used to identify genes involved in many complex diseases, including various phenotypes of the thyroid gland. In GWAS of autoimmune thyroid diseases, many susceptibility loci associated with autoimmunity (human leukocyte antigen [HLA], protein tyrosine phosphatase, non-receptor type 22 [PTPN22], cytotoxic T-lymphocyte associated protein 4 [CTLA4], and interleukin 2 receptor subunit alpha [IL2RA]) or thyroid-specific genes (thyroid stimulating hormone receptor [TSHR] and forkhead box E1 [FOXE1]) have been identified. Regarding thyroid function, many susceptibility loci for levels of TSH and free T4 have been identified through genome-wide analyses. In GWAS of differentiated thyroid cancer, associations at FOXE1, MAP3K12 binding inhibitory protein 1 (MBIP)-NK2 homeobox 1 (NKX2-1), disrupted in renal carcinoma 3 (DIRC3), neuregulin 1 (NRG1), and pecanex-like 2 (PCNXL2) have been commonly identified in people of European and Korean ancestry, and many other susceptibility loci have been found in specific populations. Through GWAS of various thyroid-related phenotypes, many susceptibility loci have been found, providing insights into the pathogenesis of thyroid diseases and disease co-clustering within families and individuals.
Autoimmunity ; Genes, Homeobox ; Genetics ; Genome-Wide Association Study* ; Graves Disease ; Hashimoto Disease ; Humans ; Leukocytes ; Neuregulin-1 ; Phenotype ; Protein Tyrosine Phosphatase, Non-Receptor Type 22 ; Receptors, Interleukin-2 ; T-Lymphocytes, Cytotoxic ; Thyroid Diseases* ; Thyroid Gland* ; Thyroid Neoplasms* ; Thyrotropin ; Thyroxine

OBJECTIVETo explore the effect and mechanism of flavones of buckwheat flower and leaf (FBFL) on lowering blood glucose and improving insulin resistance in type 2 diabetic rats.

METHODSeventy healthy male Wistar rats were used in this trial. Ten of them were selected randomly as normal group; the others were given fat milk by intragastric administration daily, from the 14th day on, low dose tetraoxypyrimidine was added by intraperitoneal injection every other day for three times. Rats with fasting (72 hours after the last injection) blood sugar > or = 16.7 mmol x L(-1) and K(IPT) < 60% of normal group were selected as type 2 diabetic model with insulin resistance, which were randomly divided into 5 groups: model group. LGLT group; low, moderate and high dosage FBFL groups (L-FBFL; M-FBFL; H-FBFL). Every rat was treated accordingly for 4 weeks; then FBG, FFA, INS were detected and ISI was calculated to evaluate the degree of insulin resistance. Liver PTP1B expression was determined by immunohistochemistry method. staining were observed by light microscopy.

RESULTFBFL could dose-dependently inhibit the rising of FBG, FFA, INS, improve the state of insulin resistance and reduce the expression level of liver PTP1B.

CONCLUSIONFBFL could effectively improve insulin resistance in type 2 diabetic rats induced by tetraoxypyrimidine and fat milk and showed dose-dependence relationship.

Animals ; Diabetes Mellitus, Type 2 ; drug therapy ; genetics ; metabolism ; Disease Models, Animal ; Fagopyrum ; chemistry ; Flavones ; administration & dosage ; Flowers ; chemistry ; Gene Expression ; drug effects ; Humans ; Insulin Resistance ; Liver ; drug effects ; metabolism ; Male ; Plant Extracts ; administration & dosage ; Plant Leaves ; chemistry ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; genetics ; metabolism ; Random Allocation ; Rats ; Rats, Wistar

OBJECTIVETo explore the possible mechanism of total flavonoids of Litsea coreana (TFLC) on reducing blood glucose level in rat with type 2 diabetes mellitus (T2DM).

METHODSMale SD rats of T2DM allocated in two groups were treated with 400 mg/kg TFLC or metformin respectively via gastrogavage for 6 weeks. Blood routine biochemical indices in rats were measured; pathology of rats' liver was examined with HE stain under transmission electron microscopy; levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in liver homogenate were determined, and the expression of protein tyrosine phosphatase 1B (PTP1B) in liver was detected using RT-PCR at the terminal of the experiment.

RESULTSBiochemical measuring showed that the glucose tolerance of rats after treatment was markedly improved in both groups. Meantime, levels of fast blood glucose (FBG), glycohemoglobin (HbA1c), fast blood insulin (FINS), free fatty acid (FFA), total cholesterol (TC), triglyceride (TG) and low density lipoprotein-cholesterol (LDL-C), as well as MDA level in liver were decreased, while levels of high density lipoprotein-cholesterol (HDL-C) in blood and SOD in liver were significantly increased in both groups after treatment, showing insignificant difference between two treatment groups. Light microscopic examination showed markedly fatty degeneration of liver, and electron microscopic examination found mitochondria swelling and endoplasmic reticulum breakage in liver of T2DM rats, but these changes were ameliorated to some extent after treatment. The elevated PTP1B expression in liver of T2DM rats was decreased in the TFLC treated group, but unchanged in the metformin treated group.

CONCLUSIONTFLC can significantly decrease the blood levels of glucose and lipid and ameliorate oxidation stress in liver; its mechanism of action in improving insulin resistance might be related with its suppression on PTP1B expression in rat's liver to enhance the insulin signaling pathway.

Animals ; Blood Glucose ; metabolism ; Diabetes Mellitus, Experimental ; drug therapy ; Diabetes Mellitus, Type 2 ; drug therapy ; Flavonoids ; isolation & purification ; therapeutic use ; Hypoglycemic Agents ; therapeutic use ; Litsea ; chemistry ; Liver ; metabolism ; Male ; Oxidative Stress ; drug effects ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; metabolism ; Rats ; Rats, Sprague-Dawley