Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Type 2 or non-insulin-dependent diabetes mellitus (NIDDM) is reaching epidemic proportions in industrialized countries. Obesity is a major factor in this disease, since about 75% of obese individuals will develop type 2 diabetes. There is an urgent need to develop new therapies for these diseases. Recently, the protein tyrosine phosphatase PTP-1B has been shown to be a negative regulator of the insulin signaling pathway, suggesting that inhibitors of this enzyme may be beneficial in the treatment of type 2 diabetes. Mice lacking PTP-1B are resistant to both diabetes and obesity.
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PMID:Role of protein tyrosine phosphatase-1B in diabetes and obesity. 1066 40

We investigated the cellular mechanism(s) of insulin resistance associated with non-insulin dependent diabetes mellitus (NIDDM) using skeletal muscles isolated from non-obese, insulin resistant type II diabetic Goto-Kakizaki (GK) rats, a well known genetic rat model for type II diabetic humans. Relative to non-diabetic control rats (WKY), insulin-stimulated insulin receptor (IR) autophosphorylation and insulin receptor substrate-1 (IRS-1) tyrosine phosphorylation were significantly inhibited in GK skeletal muscles. This may be due to increased dephosphorylation by a protein tyrosine phosphatase (PTPase). Therefore, we measured skeletal muscle total PTPase and PTPase 1B activities in the skeletal muscles isolated from control rats (WKY) and diabetic Goto-Kakizaki (GK) rats. PTPase activity was measured using a synthetic phosphopeptide, TRDIY(P)ETDY(P)Y(P)RK, as the substrate. Basal PTPase activity was 2-fold higher (P < 0.001) in skeletal muscle of GK rats when compared to WKY. Insulin infusion inhibited skeletal muscle PTPase activity in both control (26.20% of basal, P < 0.001) and GK (25.35% of basal, P < 0.001) rats. However, PTPase activity in skeletal muscle of insulin-stimulated GK rats was 200% higher than hormone-treated WKY controls (P < 0.001). Immunoprecipitation of PTPase 1B from skeletal muscle lysates and analysis of the enzyme activity in immunoprecipitates indicated that both basal and insulin-stimulated PTPase 1B activities were significantly higher (twofold, P < 0.001) in skeletal muscle of diabetic GK rats when compared to WKY controls. The increase in PTPase 1B activity in diabetic GK rats was associated with an increased expression of the PTPase 1B protein. We concluded that insulin resistance of GK rats is accompanied atleast by an abnormal regulation of PTPase 1B. Elevated PTPase 1B activity through enhanced tyrosine dephosphorylation of the insulin receptor and its substrates, may lead to impaired glucose tolerance and insulin resistance in GK rats.
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PMID:Elevated expression and activity of protein-tyrosine phosphatase 1B in skeletal muscle of insulin-resistant type II diabetic Goto-Kakizaki rats. 1092 21

A role for protein tyrosine phosphatases in the negative regulation of insulin signaling and a putative involvement in the insulin resistance associated with type 2 diabetes have been postulated since their discovery. The recent demonstration that mice lacking the protein tyrosine phosphatase-1B (PTP-1B) have enhanced insulin sensitivity validates this. Furthermore, when fed a high fat diet, these mice maintained insulin sensitivity and were resistant to obesity, suggesting that inhibition of PTP-1B activity could be a novel way of treating type 2 diabetes and obesity. This commentary reviews our current knowledge of PTP-1B in insulin signaling and its role in diabetes and discusses the development of potent and selective PTP-1B inhibitors.
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PMID:Protein tyrosine phosphatase-1B in diabetes. 1097 95

In the present study, we tested the hypothesis that variability in the protein tyrosine phosphatase-1B (PTP-1B) gene is associated with type 2 diabetes. Using single-strand conformational polymorphism analysis, we examined cDNA of PTP-1B from 56 insulin-resistant patients with type 2 diabetes as well as cDNA from 56 obese patients. Four silent variants, (NT CGA-->CGG) R199R, (NT CCC-->CCT) P303P, 3'UTR+104insG, and 3'UTR+86T-->G, and one missense variant, P387L, were found. Subsequent analysis on genomic DNA revealed two intron variants, IVS9+57C-->T and IVS9+58G-->A, and two missense variants, G381S and T420M. The G381S and 3'UTR+104insG insertion variants were not associated with type 2 diabetes. In an association study, the P387L variant was found in 14 of 527 type 2 diabetic subjects (allelic frequency 1.4%, 0.4-2.4 CI) and in 5 of 542 glucose-tolerant control subjects (allelic frequency 0.5%, CI 0.1-1.1), showing a significant association to type 2 diabetes (P = 0.036). In vitro, p34 cell division cycle (p34(cdc2)) kinase-directed incorporation of [gamma-(32)P]ATP was reduced in a mutant peptide compared with native peptide (387P: 100% vs. 387L: 28.4 +/- 5.8%; P = 0.0012). In summary, a rare P387L variant of the PTP-1B gene is associated with a 3.7 (CI 1.26-10.93, P = 0.02) genotype relative risk of type 2 diabetes in the examined population of Danish Caucasian subjects and results in impaired in vitro serine phosphorylation of the PTP-1B peptide.
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PMID:A P387L variant in protein tyrosine phosphatase-1B (PTP-1B) is associated with type 2 diabetes and impaired serine phosphorylation of PTP-1B in vitro. 1451 10

The IA-2 is a major autoantigen of type 1 diabetes belonging to the protein tyrosine phosphatase family. We report on the humoral autoimmunity to an alternatively-spliced variant of IA-2 (IA-2 variant) and autoimmune-mediated diabetes age of onset association with IA-2 autoantibody epitope specificities, in 144 recent-onset patients with type 1 diabetes and 54 GAD autoantibody-positive patients with type 2 diabetes. The cytoplasmic domain of IA-2 (IA-2ic) detected a somewhat greater proportion of patients expressing autoantibodies than IA-2 variant (56%vs. 52% of patients with type 1 diabetes and 17%vs. 9% of GAD autoantibody-positive patients with type 2 diabetes). Conversely, only 1% of IA-2 variant autoantibody-positive patients failed to react to IA-2ic construct. Among 80 patients with type 1 diabetes who were positive for autoantibodies to IA-2ic, 8% recognized the juxtamembrane region (JM, representing amino acids 601-629) only, 64% bound the protein tyrosine phosphatase (PTP)-like domain of IA-2 only, and 29% bound both JM and PTP epitopes. Autoantibodies to the PTP-like domain were prevalent in children and adolescents with type 1 diabetes. The age of disease onset in patients with IA-2JM autoantibodies only, was significantly higher than those in patients reacted with the PTP-like domain of IA-2 (P< 0.02). Among GAD autoantibody-positive patients with type 2 diabetes reacted with IA-2ic, 44% bound the JM region only, and 33% bound epitopes in the PTP-like domain only; 22% had autoantibodies to both regions. The frequency of GAD autoantibody-positive patients with type 2 diabetes positive for autoantibodies to the JM region only, was significantly higher than that in patients with type 1 diabetes (P< 0.01). IA-2PTP autoantibodies were significantly associated with HLA-DR4, while the additional reactivity to IA-2JM was associated with HLA-DR9 allele. These results suggest that autoantibody recognition of IA-2 epitopes in autoimmune diabetes is associated with age of disease onset, which may reflect the intensity of the beta-cell destruction process.
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PMID:Association between IA-2 autoantibody epitope specificities and age of onset in Japanese patients with autoimmune diabetes. 1177 57

To evaluate the frequency of autoantibodies to glutamic acid decarboxylase (GAD), protein tyrosine phosphatase-like protein (IA-2), and insulin (IAA) in children with type 2 diabetes mellitus (DM), we studied 37 children and adolescents whose type 2 DM was defined by fasting and 90-min standard liquid meal-stimulated serum C-peptide levels of >0.2 and >0.5 nmol/l (0.7 and 1.5 ng/ml), respectively. Mean fasting-stimulated serum C-peptide levels were 1.1 +/- 0.10 nmol/l (3.38 +/- 0.29 ng/ml) and 1.9 +/- 0.17 nmol/l (5.79 +/- 0.50 ng/ml), respectively. Eleven out of 37 patients (29.7%) were positive for at least one autoantibody: 8.1% (n = 3) had positive GAD, 8.1% (n = 3) had positive IA-2, and 27% (n = 10) had positive IAA. Nine of the 10 IAA-positive patients were on insulin treatment at the time of testing. Three of the 10 IAA-positive patients were also positive for GAD or IA-2. Since insulin treatment can stimulate IAA, we considered this to be less informative in classifying autoimmunity in DM. Therefore, GAD and IA-2 were considered primary autoimmune markers. Four out of 37 patients (10.8%) were positive for GAD (n = 3) or IA-2 (n = 3) or both (n = 2). Thus, low (10.8%) frequency of autoimmunity in children and adolescents is consistent with their clinical classification of type 2 DM based on the presence of residual C-peptide.
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PMID:Autoantibodies in children with type 2 diabetes mellitus. 1201 27

In Latvia diabetes mellitus is diagnosed using the WHO's clinical criteria; assays for the detection of autoantibodies are not available, and hence slowly progressive autoimmune diabetes is likely to be missed. Autoantibodies against glutamic acid decarboxylase (GAD65) and protein tyrosine phosphatase (IA-2) among patients with clinically diagnosed NIDDM identify group of patients with slow-onset type 1 diabetes or LADA. The aim of this study was to estimate the risk of polyendocrine autoimmunity among clinically diagnosed NIDDM patients from Latvia. One hundred NIDDM patients and 100 healthy controls were tested for GAD65 and IA-2 autoantibodies as well as 21-hydroxylase (21-OH) and tissue transglutaminase (TTG) antibodies by RIA assay. Age at onset was >or= 30 years, and duration of disease less than 5 years. Of 100 patients, 85 were on oral hypoglycemic agents and 15 were on insulin. Body mass index (BMI) under 19 was recorded in 1% (1 of 100 cases), while overweight (BMI > 25.5 in females and 27 in males) was documented in 45% (45 of 100 cases). GAD65 antibodies were found in 30 of 100 (30%) and IA-2 antibodies in 40 of 100 (40%) patients. Either GAD65 or IA-2 antibodies were found in 55 of 100 (55%). None of the patients carried antibodies against 21-OH and only 1 of 100 (1%) carried antibodies against TTG. From the results obtained in our study we conclude that in Latvian adult NIDDM subjects, islet autoantibodies identify groups of slow-onset type 1 diabetes but not polyendocrine autoimmunity.
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PMID:Islet autoantibodies in Latvian subjects with non-insulin-dependent diabetes mellitus: slow-onset type 1 diabetes or polyendocrine autoimmunity? 1202 Nov 19

Type 2 diabetes is increasing at an alarming rate worldwide, and there has been a considerable effort in several laboratories to identify suitable targets for the design of drugs against the disease. To this end, the protein tyrosine phosphatases that attenuate insulin signaling by dephosphorylating the insulin receptor (IR) have been actively pursued. This is because inhibiting the phosphatases would be expected to prolong insulin signaling and thereby facilitate glucose uptake and, presumably, result in a lowering of blood glucose. Targeting the IR protein tyrosine phosphatase, therefore, has the potential to be a significant disease-modifying strategy. Several protein tyrosine phosphatases (PTPs) have been implicated in the dephosphorylation of the IR. These phosphatases include PTPalpha, LAR, CD45, PTPepsilon, SHP2, and PTP1B. In most cases, there is evidence for and against the involvement of the phosphatases in insulin signaling. The most convincing data, however, support a critical role for PTP1B in insulin action. PTP1B knockout mice are not only insulin sensitive but also maintain euglycemia (in the fed state), with one-half the level of insulin observed in wild-type littermates. Interestingly, these mice are also resistant to diet-induced obesity when fed a high-fat diet. The insulin-sensitive phenotype of the PTP1B knockout mouse is reproduced when the phosphatase is also knocked down with an antisense oligonucleotide in obese mice. Thus PTP1B appears to be a very attractive candidate for the design of drugs for type 2 diabetes and obesity.
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PMID:Protein tyrosine phosphatases: the quest for negative regulators of insulin action. 1262 22

In this study we have explored whether the bifunctional protein semicarbazide-sensitive amine oxidase (SSAO)/vascular adhesion protein-1 (VAP-1) represents a novel target for type 2 diabetes. To this end, Goto-Kakizaki (GK) diabetic rats were treated with the SSAO substrate benzylamine and with low ineffective doses of vanadate previously shown to have antidiabetic effects in streptozotocin-induced diabetic rats. The administration of benzylamine in combination with vanadate in type 2 diabetic rats acutely stimulated glucose tolerance, and the chronic treatment normalized hyperglycemia, stimulated glucose transport in adipocytes, and reversed muscle insulin resistance. Acute in vivo administration of benzylamine and vanadate stimulated skeletal muscle glucose transport, an effect that was also observed in incubated muscle preparations coincubated with adipose tissue explants or with human recombinant SSAO. Acute administration of benzylamine/vanadate also ameliorated insulin secretion in diabetic GK rats, and this effect was also observed in incubated pancreatic islets. In keeping with these observations, we also demonstrate that pancreatic islets express SSAO/VAP-1. As far as mechanisms of action, we have found that benzylamine/vanadate causes enhanced tyrosine phosphorylation of proteins and reduced protein tyrosine phosphatase activity in adipocytes. In addition, incubation of human recombinant SSAO, benzylamine, and vanadate generates peroxovanadium compounds in vitro. Based on these data, we propose that benzylamine/vanadate administration generates peroxovanadium locally in pancreatic islets, which stimulates insulin secretion and also produces peroxovanadium in adipose tissue, activating glucose metabolism in adipocytes and in neighboring muscle. This opens the possibility of using the SSAO/VAP-1 activity as a local generator of protein tyrosine phosphatase inhibitors in antidiabetic therapy.
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PMID:Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 activity exerts an antidiabetic action in Goto-Kakizaki rats. 1266 73

The leukocyte common antigen-related protein, LAR, is a receptor-like protein tyrosine phosphatase (PTP) which has a wide tissue distribution. Post-translational processing cleaves the proprotein into two non-covalently associated subunits, an extracellular subunit resembling a cell adhesion molecule with three immunoglobulin-like domains and eight fibronectin III-like domains, and a phosphatase subunit containing a short extracellular domain, a transmembrane segment, and tandem cytoplasmic PTP catalytic domains. Current evidence supports a role for LAR in cadherin complexes where it associates with and dephosphorylates beta-catenin, a pathway which may be critical for cadherin complex stability and cell-cell association. LAR also localizes to focal adhesions. Evidence strongly suggests that LAR is involved in axon guidance in the developing nervous system, being localized through association with alpha-liprins. Finally, considerable data support a role for LAR in negatively regulating the insulin receptor signaling. Now that targeting of specific PTPs for therapeutic inhibition is a reality, the clinically relevant pathways requiring LAR must be identified. Inhibition of LAR might improve insulin sensitivity in patients with insulin resistance and type 2 diabetes. Unfortunately, the LAR knockout mouse displays no improvement in insulin sensitivity but rather has defects in terminal mammary gland development and in basal forebrain cholinergic neurons. With LAR being implicated in diverse pathways, additional investigations are needed before clinical targets for therapeutic inhibition of LAR can be predicted. However, selective inhibitors of LAR would be valuable reagents to probe the function of LAR, particularly in animal studies where the most susceptible LAR-dependent pathway(s) must be determined.
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PMID:The leukocyte common antigen-related protein LAR: candidate PTP for inhibitory targeting. 1267 46


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