Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

High-throughput screening (HTS) of compound libraries is used to discover novel leads for drug development. When a structure is available for the target, computer-based screening using molecular docking may also be considered. The two techniques have rarely been used together on the same target. The opportunity to do so presented itself in a project to discover novel inhibitors for the enzyme protein tyrosine phosphatase-1B (PTP1B), a tyrosine phosphatase that has been implicated as a key target for type II diabetes. A corporate library of approximately 400 000 compounds was screened using high-throughput experimental techniques for compounds that inhibited PTP1B. Concurrently, molecular docking was used to screen approximately 235 000 commercially available compounds against the X-ray crystallographic structure of PTP1B, and 365 high-scoring molecules were tested as inhibitors of the enzyme. Of approximately 400 000 molecules tested in the high-throughput experimental assay, 85 (0.021%) inhibited the enzyme with IC50 values less than 100 microM; the most active had an IC50 value of 4.2 microM. Of the 365 molecules suggested by molecular docking, 127 (34.8%) inhibited PTP1B with IC50 values less than 100 microM; the most active of these had an IC50 of 1.7 microM. Structure-based docking therefore enriched the hit rate by 1700-fold over random screening. The hits from both the high-throughput and docking screens were dissimilar from phosphotyrosine, the canonical substrate group for PTP1B; the two hit lists were also very different from each other. Surprisingly, the docking hits were judged to be more druglike than the HTS hits. The diversity of both hit lists and their dissimilarity from each other suggest that docking and HTS may be complementary techniques for lead discovery.
 ...
PMID:Molecular docking and high-throughput screening for novel inhibitors of protein tyrosine phosphatase-1B. 1201 59

This article aims to estimate the prevalence of SOX13 antibodies in Swedish patients with type 1 diabetes and healthy controls. The patients (n = 102; median age 35 years [range, 9-89]) were newly diagnosed with type 1 diabetes in a defined area in southern Sweden during 1995-1998. Islet cell antibodies (ICA) were analyzed with immunofluorescence, while glutamic acid decarboxylase antibodies (GADA), tyrosine phosphatase antibodies (IA-2A), and antibodies against the transcription factor SOX13 (SOX13Ab) were analyzed with radioimmunoprecipitating assays. SOX13Ab were found in 9.8% (10/102) of type 1 patients compared to 2.0% (2/99) in healthy controls (P = 0.033). At least one of the four autoantibodies (ICA, GADA, IA-2A or SOX13Ab) were identified in 67% (68/102) of the patients. Samples positive for IA-2A were only in one case positive also for SOX13Ab. IA-2A-positive patients were often positive also for ICA and GADA (19/27), and the same combination was also common for SOX13Ab-positive patients (6/10). Only 2.0% (2/102) were positive for SOX13Ab alone. ICA, GADA and IA-2A were more frequent in younger patients (<or= 35 years of age) than in older patients, while SOX13Ab showed similar frequency in both groups. We concluded that the frequency of SOX13Ab was significantly increased in Swedish patients with type 1 diabetes, but that the addition of SOX13Ab to the combination of GADA and IA2-A only increased the sensitivity by 2% for autoimmune diabetes. Therefore, SOX13 could be a minor autoantigen involved in the pathogenesis of type 1 diabetes.
 ...
PMID:Increased autoantibodies to SOX13 in Swedish patients with type 1 diabetes. 1202 Nov 10

Women with gestational diabetes mellitus (GDM) have considerable risk for developing both type 1 and type 2 diabetes in life. Autoantibodies against glutamic acid decarboxylase (GAD65) and tyrosine phosphatase (IA-2) are strongly associated with autoimmune diabetes and can be useful in early identification of the development of type 1 diabetes in women with GDM. On the other hand antibodies against minor islet antigens in adults can be predictors for autoimmune polyendocrine syndrome. The aim of our study was to estimate the prevalence of autoantibodies against minor antigens-tissue transglutaminase (TTG), ICA12, and 21-hydroxylase (21-0H)-in GDM patients from southern India. Eighty-six serum samples from GDM subjects and 114 samples from healthy controls were tested for the presence of GAD65 and IA-2Ab as well as for the presence of 21-OH, TTG, and ICA12Ab by radiobinding assay with in vitro translated recombinant human 35S-GAD65, IA-2, TTG, ICA12, and 21-OH antigens. We observed the presence of GAD65 or IA-2 autoantibodies in 41% (35/86) of GDM patients, while none of the patients tested positive for any of the minor autoantibodies. Our results demonstrate that there is a high prevalence of autoantibodies in GDM subjects that are at higher risk of developing autoimmune diabetes later, but none of the patients carries antibodies against minor antigens, which could predict autoimmune polyendocrine syndrome in adults.
 ...
PMID:Women diagnosed with gestational diabetes mellitus do not carry antibodies against minor islet cell antigens. 1202 Nov 24

Autoantibodies found in cord blood in children who later develop diabetes might be produced by the fetus. If so, continuous autoantibody production would still be expected in these children at one year of age. We decided to determine autoantibodies in cord blood and to see whether they persisted in these children at one year. Autoantibodies against GAD65 (glutamic acid decarboxylase) and IA-2 (tyrosine phosphatase) in cord blood were determined in 2,518 randomly selected children. Forty-nine (1.95%) were positive for GAD65 antibodies, 14 (0.56%) were positive for IA-2 antibodies, and 3 of them were positive for both GAD and IA-2. Four of the mothers of children with GAD65 autoantibodies in cord blood (8.2%) had type 1 diabetes as did 5 mothers of children with IA-2 antibodies (35.7 %), but only 0.4% of the mothers had type 1 diabetes in the autoantibody-negative group (P < 0.001). Information on infections during pregnancy was available in 2,169 pregnancies. In the autoantibody-positive group, 31.5% had an infection during pregnancy, which was more common than in the autoantibody-negative group of 500 children with the lowest values (20.1%; P < 0.04). At one year follow-up nobody of those with positive cord blood had GAD65 or IA-2 autoantibodies. We conclude that most autoantibodies found in cord blood samples of children are probably passively transferred from mother to child. Antibody screening of cord blood cannot be used to predict diabetes in the general population. Infections during pregnancy may initiate an immune process related to diabetes development.
 ...
PMID:Diabetes-related autoantibodies in cord blood from children of healthy mothers have disappeared by the time the child is one year old. 1202 Nov 26

IA-2 is a major autoantigen in type 1 diabetes. Autoantibodies to IA-2 appear years before the development of clinical disease and are being widely used as predictive markers to identify individuals at risk for developing type 1 diabetes. IA-2 is an enzymatically inactive member of the transmembrane protein tyrosine phosphatase family and is an integral component of secretory granules in neuroendocrine cells. To study its function, we generated IA-2-deficient mice. Northern and Western blot analysis showed that neither IA-2 mRNA nor protein was expressed. Physical examination of the IA-2(- /-) animals and histological examination of tissues failed to reveal any abnormalities. Nonfasting blood glucose levels, measured over 6 months, were slightly elevated in male IA-2(-/-) as compared to IA-2(+ /+) littermates, but remained within the nondiabetic range. Glucose tolerance tests, however, revealed statistically significant elevation of glucose in both male and female IA-2(-/-) mice and depressed insulin release. In vitro glucose stimulation of isolated islets showed that male and female mice carrying the disrupted gene released 48% (P < 0.001) and 42% (P < 0.01) less insulin, respectively, than mice carrying the wild-type gene. We concluded that IA-2 is involved in glucose-stimulated insulin secretion.
Diabetes 2002 Jun
PMID:Targeted disruption of the protein tyrosine phosphatase-like molecule IA-2 results in alterations in glucose tolerance tests and insulin secretion. 1203 72

Type 1 diabetes in most Asian populations may not have a salient autoimmune basis when assessed with single determinations of the major markers, islet cell antibodies (ICAs) and glutamic acid decarboxylase antibodies (GAD65ab). With the inclusion of antibodies to tyrosine phosphatase-like protein IA-2 (IA-2ab) as an additional major marker, we re-examined autoimmune diabetes in a group of Chinese patients. We studied 272 subjects at various stages of disease with blood samples procured for biochemical analysis. ICAs were measured by immunofluorescence, GAD65ab and IA-2ab by radioimmunoassay. Sixty-seven patients fulfilled clinical diagnosis of type 1 diabetes and the remaining 205 patients were type 2. Prevalence of single autoantibody type in recent-onset type 1 diabetes ( < 1 year duration; n = 47) showed 10.6% with ICAs, 44.7% GAD65ab and 36.2% IA-2ab. GAD65ab account for more than two-thirds of the markers found in type 1 diabetes. Combined analysis further showed that 51.1% had at least one antibody type, 31.9% with two or more antibodies and 8.5% with all three antibodies. Islet autoimmunity presence in childhood-onset type 1 diabetes improved with the addition of IA-2ab, though less impact was seen in the adult-onset. Similarly, combined analysis for type 2 patients with recent diabetes showed a modest increase to 13% with islet autoimmunity compared to 8% when assessed by GAD65ab alone. Combining IA-2ab and GAD65ab assays results detected slightly more immune-mediated diabetes, compared to using a single GAD65ab determination. Non-autoimmune causes need to be considered in the pathogenesis of type 1 diabetes in Chinese, particularly in adults.
 ...
PMID:Tyrosine phosphatase-like protein (IA-2) and glutamic acid decarboxylase (GAD65) autoantibodies: a study of Chinese patients with diabetes mellitus. 1207 31

Type 1A diabetes mellitus has become one of the most intensively studied autoimmune disorders, with characterized animal models and extensive prospective studies of the development of anti-islet autoimmunity. It is now possible to predict the development of type 1A diabetes mellitus, beginning with HLA-encoded genetic susceptibility, followed by the development of a series of anti-islet autoantibodies. Prediction primarily is based on the detection of multiple anti-islet autoantibodies reacting with cloned islet antigens. Multiple international workshops fostered the development of specific and sensitive radioassays for autoantibodies reacting with GAD65 (glutamic acid decarboxylase), ICA512 (also termed IA-2, a tyrosine phosphatase-like protein), and insulin. Similar high throughput radioassays have been applied using autoantigens for additional autoimmune disorders including celiac disease and Addison's disease. Relatives of patients with type 1A diabetes mellitus inherit susceptibility to express multiple autoantibodies, and a subset of autoantibody-positive individuals inherit susceptibility to progress to overt disease. This article reviews autoimmune disorders associated with type 1A diabetes mellitus.
 ...
PMID:Type 1A diabetes mellitus-associated autoimmunity. 1209 57

Cytokines released from activated antigen-presenting cells and T-lymphocytes are crucially involved in the pathogenesis of type 1 diabetes. Previous studies have shown that proinflammatory cytokines play an important role in the induction of autoimmunity and beta-cell damage. Inhibition of insulin expression has been described, but their effects on other major target autoantigens, such as the tyrosine phosphatase-like protein IA-2, is not known. In the present study, we established sensitive real-time RT-PCR to measure IA-2, insulin, and inducible nitric oxide (NO) synthase (iNOS) mRNA expression. Rat insulinoma INS-1 cells were stimulated with IL-1beta, TNF-alpha, interferon (IFN)-gamma, and IL-2 as well as with two combinations of these cytokines (C1: IL-1beta + TNF-alpha + IFN-gamma; C2: TNF-alpha + IFN-gamma). Treatment with IL-1beta, TNF-alpha, or IFN-gamma alone caused a significant down-regulation of IA-2 and insulin mRNA levels in a time and dose-dependent manner, whereas IL-2 had no effect. Exposure to cytokine combinations strongly potentiates the inhibitory effects. Incubation of cells with C1 and C2 for 24 h induces a significant inhibition of IA-2 mRNA levels by 78% and 58%, respectively. Under these conditions, an up to 5 x 10(4)-fold increase of iNOS gene expression was observed. The hypothesis that the formation of NO is involved in IA-2 regulation was confirmed by the finding that the coincubation of C1 with 4 mM L-N(G)-monomethyL-L-arginine, an inhibitor of the iNOS, partly reversed the down-regulation of IA-2. Further, incubation with the synthetic NO-donor S-nitroso-N-acetyl-D-L-penicillamine significantly decreased IA-2 mRNA level to 51% of basal levels. In conclusion, we have demonstrated for the first time that IL-1beta, TNF-alpha, and IFN-gamma exert a strong inhibitory effect on expression of the diabetes autoantigen IA-2. The action of IL-1beta may be partly mediated by the activation of the NO pathway.
 ...
PMID:Effect of proinflammatory cytokines on gene expression of the diabetes-associated autoantigen IA-2 in INS-1 cells. 1223 95

IA-2 and phogrin are tyrosine phosphatase-like proteins that may mediate interactions between secretory granules and cytoskeleton in islets and neuroendocrine tissues. We investigated factors that regulate IA-2 and phogrin expression and their relationship to maturation of insulin secretory responses that occur after birth. Islet content of IA-2, but not phogrin, increased during the first 10 days of life in rats, when insulin secretion in response to glucose increased to adult levels. In cultured 5-day-old rat islets, IA-2 protein and mRNA was increased by glucose and agents that potentiate insulin secretion by the cAMP pathway. Addition of insulin increased IA-2 protein levels and insulin biosynthesis without affecting IA-2 mRNA. Blocking insulin secretion with diazoxide or insulin action with insulin receptor antibodies inhibited glucose-induced increases in IA-2 protein, but not those of mRNA. Phogrin expression was unchanged by all agents. Thus, IA-2 is regulated at the mRNA level by glucose and elevated cAMP, whereas locally secreted insulin modulates IA-2 protein levels by stimulating biosynthesis. In contrast, phogrin expression is insensitive to factors that modify beta-cell function. These results demonstrate differential regulation of two closely related secretory granule components and identify IA-2 as a granule membrane protein subject to autocrine regulation by insulin.
Diabetes 2002 Oct
PMID:Different regulated expression of the tyrosine phosphatase-like proteins IA-2 and phogrin by glucose and insulin in pancreatic islets: relationship to development of insulin secretory responses in early life. 1235 37

Circulating autoantibodies (Ab) to islet autoantigens, glutamic acid decarboxylase (GAD(65)), and tyrosine phosphatase ICA512/IA-2 have been proposed as predictive markers of type 1 diabetes mellitus. To ascertain residual beta-cell function and the clinical relevance for monitoring autoimmunity after clinical manifestation of disease, we studied 63 children at diagnosis of type 1 diabetes (mean SD age 7.5 +/- 4 years) and 91 adolescent patients with type 1 diabetes (age 14.7 +/- 1.6 years) with a mean duration of disease of 7 +/- 3.5) years. Forty-two normal adolescent subjects (age 14.6 +/- 1.8 years) without a family history of diabetes were the control group. Anti-GAD(65) and ICA512/IA-2 Ab were assessed by a quantitative radioimmunoprecipitation assay. The relationship between humoral autoimmunity and clinical parameters was explored. GAD(65) and ICA512/IA-2 Ab were detected in 56% and 63% of newly diagnosed children and the prevalence was not different in relationship to clinical characteristics. Levels of GAD(65) Ab positively correlated with diagnosis age (P <.05). Both Ab were associated with islet cell antibodies (ICA) (P <.05), but one fifth of patients had at least 1 of the 2 Ab and absent ICA. At onset, only age showed a significant relationship to residual C-peptide secretion. Among the cohort of patients with diabetes of short-mid duration, GAD(65) and ICA512/IA-2 Ab were present in 44% and 45% of cases (P >.05 and P <.05 v newly diagnosed children, respectively) and more patients were identified by these Ab (68%) than by ICA alone (34%) (P <.05). In this cohort, levels of ICA512/IA-2 Ab negatively correlated with levels of glycosylated hemoglobin (HbA(1c)) (P <.005) and with daily insulin requirement (P <.05). Moreover, the presence of some residual C-peptide secretion was significantly associated with the presence of ICA512/IA-2 Ab (P <.05). Our findings confirm that positivity for either GAD(65) or ICA512/IA-2 Ab is a highly sensitive marker of type 1 diabetes in the pediatric age group, identifying a group of patients with absent ICA immunofluorescence. The persistence of Ab to islet tyrosine phosphatase possibly represents a marker of better glycemic control and less insulin requirement, indicating residual beta-cell function, thus conferring clinical and prognostic relevance to these Ab, as well as potential usefulness in intervention strategies.
 ...
PMID:Glutamic acid decarboxylase and ICA512/IA-2 autoantibodies as disease markers and relationship to residual beta-cell function and glycemic control in young type 1 diabetic patients. 1252 58


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>