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

It has recently been proposed that the islet 64,000 Mr protein autoantigen (64K) of insulin-dependent diabetes mellitus (IDDM) is glutamic acid decarboxylase (GAD). We evaluated, by means of a newly developed immunotrapping enzyme activity assay (ITEAA), the prevalence of circulating GAD-autoantibodies (Ab) in a large population of IDDM patients (n = 168), blood donors (n = 87) and non-diabetic autoimmune patients (n = 40). The latter two groups were used as controls. Overall, GAD-Ab were found in 22% of IDDM patients, but in none of the two control groups (P = 0.007). These specificities were invariably associated with islet cell antibodies (ICA) (31.6% in IDDM with ICA vs 0 in IDDM without ICA, P = 0.0001), and this prevalence was higher in sera with high titer ICA (54.5% in IDDM with ICA greater than 80 JDF-units vs 22.6% of IDDM with ICA 5-80 JDF units; P = 0.002). Moreover, GAD-Ab were associated with the female sex (P = 0.002) and the concomitant presence of thyroid and/or gastric antibodies (P = 0.002). No correlation was observed between GAD-Ab and age of the patients, duration of IDDM, or associated non-organ specific antibodies. Our study indicates that GAD-Ab measured by ITEAA are: (1) detected in a proportion of IDDM patients; (2) strongly associated with ICA; (3) preferentially found in IDDM female patients with autoimmune polyendocrine serology; and (4) detected with lower frequency than that reported for 64K-Ab in IDDM.
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PMID:Autoantibodies to glutamic acid decarboxylase (GAD) detected by an immuno-trapping enzyme activity assay: relation to insulin-dependent diabetes mellitus and islet cell antibodies. 181 96

Glutamic acid decarboxylase (GAD; glutamate decarboxylase, L-glutamate 1-carboxy-lyase, EC 4.1.1.15), which catalyzes formation of gamma-aminobutyric acid from L-glutamic acid, is detectable in different isoforms with distinct electrophoretic and kinetic characteristics. GAD has also been implicated as an autoantigen in the vastly differing autoimmune disease stiff-man syndrome and insulin-dependent diabetes mellitus. Despite the differing GAD isoforms, only one type of GAD cDNA (GAD-1), localized to a syntenic region of chromosome 2, has been isolated from rat, mouse, and cat. Using sequence information from GAD-1 to screen a human pancreatic islet cDNA library, we describe the isolation of an additional GAD cDNA (GAD-2), which was mapped to the short arm of human chromosome 10. Genomic Southern blotting with GAD-2 demonstrated a hybridization pattern different from that detected by GAD-1. GAD-2 recognizes a 5.6-kilobase transcript in both islets and brain, in contrast to GAD-1, which detects a 3.7-kilobase transcript in brain only. The deduced 585-amino acid sequence coded for by GAD-2 shows less than 65% identity to previously published, highly conserved GAD-1 brain sequences, which show greater than 96% deduced amino acid sequence homology among the three species. The function of this additional islet GAD isoform and its importance as an autoantigen in insulin-dependent diabetes remain to be determined.
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PMID:Cloning and primary structure of a human islet isoform of glutamic acid decarboxylase from chromosome 10. 192 93

A 64-kDa islet protein is a major autoantigen in insulin-dependent diabetes mellitus (IDDM). Autoantibodies against the 64-kDa protein were recently shown to immunoprecipitate glutamic acid decarboxylase (GAD; L-glutamate 1-carboxy-lyase, EC 4.1.1.15) from brain and from islets. We present evidence that the autoantisera also recognize a hydrophilic islet protein of approximately 67 kDa in addition to the amphiphilic 64-kDa form. We have isolated a full-length rat islet GAD cDNA encoding a hydrophilic 67-kDa protein, which appears to be identical to rat brain 67-kDa GAD. A partial sequence of human insulinoma 67-kDa GAD was identical to human brain 67-kDa GAD. Allelic variations were observed in rat as well as in human 67-kDa GAD sequences. The expressed rat islet 67-kDa GAD protein is functional and is immunoprecipitated by IDDM sera; it comigrates electrophoretically with the 67-kDa islet autoantigen. The hydrophilic 67-kDa form of GAD in islets is an additional autoantigen in IDDM and is recognized by a different subset of autoantibodies than the 64-kDa autoantigen. Thus, mammalian cell lines expressing functionally active, recombinant GAD may become important tools to study the nature and the role of GAD autoreactivity in IDDM.
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PMID:Cloning, characterization, and autoimmune recognition of rat islet glutamic acid decarboxylase in insulin-dependent diabetes mellitus. 192 35

Autoimmune diseases result from the activation of self-reactive T cells induced by autoantigens or by foreign antigens cross-reactive with an autoantigen. A striking characteristic of autoimmune diseases is the increased frequency of certain HLA alleles in affected individuals. Moreover, as demonstrated for example in rheumatoid arthritis and insulin-dependent diabetes mellitus, class II alleles positively associated with autoimmune diseases share amino acid residues in the hypervariable HLA regions involved in peptide binding. Therefore, it is likely that disease-associated HLA class II molecules have the capacity to bind the autoantigen and present it to T cells, thereby inducing and maintaining, under appropriate conditions, the autoimmune disease. The data reviewed here demonstrate MHC-selective inhibition of antigen-induced T cell responses in vivo by parenterally administered soluble, MHC-binding peptide competitors, under conditions in which the competitor is not immunogenic. This suggests the feasibility of a therapeutic approach based on MHC blockade in the treatment of HLA-linked autoimmune diseases.
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PMID:Inhibition of T cell activation by blockade of MHC class II molecules. 193 5

Autoantibody to a rat islet cell-protein of 38 kilodalton was detectable at around 30 days of age in the sera of diabetes-prone Biobreeding (DP-BB) rats by both immunoprecipitation and differential Western blotting methods. Anti-38 kilodalton islet cell autoantibody was not, however, observed in the sera from 5- to 20-day-old DP-BB rats. Over 90% of DP-BB rats in which the antibody was detected, eventually developed Type 1 (insulin-dependent) diabetes mellitus. The antibody disappeared within 2 weeks after diabetes onset. However, it was preserved in the sera of DP-BB rats which had been treated with silica to prevent insulitis. The anti-38 kilodalton islet cell autoantibody was not detected in sera from control Wistar Furth (WF) rats. The autoantibody also cross-reacted with a rat insulinoma (RINm5F) cell protein of 38 kilodalton, but did not react with protein from mouse fibroblast (L-929 cells), rat pituitary cells (GH3 cells), or normal rat lymphocytes. The production of the autoantibody appears to be pancreatic Beta-cell dependent, since the autoantibody disappears after almost complete depletion of Beta cells, but is consistently present as long as Beta cells remain. Identification of the Beta-cell dependent anti-38 kilodalton islet cell autoantibody, which cross-reacts with a rat insulinoma cell protein of 38 kilodalton and precedes the onset of Type 1 diabetes in BB rats, will be invaluable for study of the molecular nature of a target islet cell autoantigen associated with the induction of autoimmunity in DP-BB rats.
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PMID:Studies on autoimmunity for initiation of beta-cell destruction. VIII. Pancreatic beta-cell dependent autoantibody to a 38 kilodalton protein precedes the clinical onset of diabetes in BB rats. 193 57

The 64-kDa pancreatic beta-cell autoantigen, which is a target of autoantibodies associated with early as well as progressive stages of beta-cell destruction, resulting in insulin-dependent diabetes (IDDM) in humans, has been identified as the gamma-aminobutyric acid-synthesizing enzyme glutamic acid decarboxylase. We have identified two autoantigenic forms of this protein in rat pancreatic beta-cells, a Mr 65,000 (GAD65) hydrophilic and soluble form of pI 6.9-7.1 and a Mr 64,000 (GAD64) component of pI 6.7. GAD64 is more abundant than GAD65 and has three distinct forms with regard to cellular compartment and hydrophobicity. A major portion of GAD64 is hydrophobic and firmly membrane-anchored and can only be released from membrane fractions by detergent. A second portion is hydrophobic but soluble or of a low membrane avidity, and a third minor portion is soluble and hydrophilic. All the GAD64 forms have identical pI and mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results of pulse-chase labeling with [35S]methionine are consistent with GAD64 being synthesized as a soluble protein that is processed into a firmly membrane-anchored form in a process which involves increases in hydrophobicity but no detectable changes in size or charge. All the GAD64 forms can be resolved into two isoforms, alpha and beta, which differ by approximately 1 kDa in mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis but are identical with regard to all other parameters analyzed in this study. GAD65 has a shorter half-life than the GAD64 forms, remains hydrophilic and soluble, and does not resolve into isomers. Comparative analysis of the brain and beta-cell forms of GAD show that GAD65 and GAD64 in pancreatic beta-cells correspond to the larger and smaller forms of GAD in brain, respectively. The expression of different forms and the flexibility in subcellular localization of the GAD autoantigen in beta-cells may have implications for both its function and autoantigenicity.
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PMID:Pancreatic beta cells express two autoantigenic forms of glutamic acid decarboxylase, a 65-kDa hydrophilic form and a 64-kDa amphiphilic form which can be both membrane-bound and soluble. 174 45

Using serum from a prediabetic patient as a probe, we screened 0.5 x 10(6) recombinants from a rat islet lambda gt11 expression library. One plaque-producing antigen reactive with this prediabetic serum was identified, subcloned, and sequenced. Analysis of the sequence reveals that the clone encodes a 136-amino acid fragment of carboxypeptidase-H (enkephalin convertase). Carboxypeptidase-H is a molecule expressed within islet secretory granules and neurendocrine cells. The patient whose antibodies recognize this recombinant molecule (termed DG-1) was negative for anti-DG-1 antibodies in 1984, developed the antibodies by 1986, and remained positive until the development of diabetes in 1988. To date, serum from 5 of 20 cytoplasmic islet cell antibody-positive relatives reacted with the expressed protein, while none of 14 control sera reacted. On Western blotting, the initial patient's serum used for the screening reacts with a 52-kDa antigen corresponding to the mol wt of the membrane form of carboxypeptidase-N. The current study has identified carboxypeptidase-H as an autoantigen recognized by serum of pretype I diabetes, and the methodology used should aid in identification of additional autoantigens associated with type I diabetes.
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PMID:Identification and cloning of a granule autoantigen (carboxypeptidase-H) associated with type I diabetes. 195 1

Cellular autoimmunity is thought to be primarily responsible for the selective destruction of islet beta cells in Type I diabetes. Why the T lymphocyte reacts to self and recognizes the beta cell as foreign, as against the other endocrine islet cells, is unknown. One key issue is whether the beta cell itself is capable of presenting autoantigen(s) and thereby breaking T lymphocyte tolerance. In this paper we discuss current concepts of antigen presentation and relate these to recent findings from our laboratory, suggesting that the beta cell can be induced to display many of the phenotypic properties of classical antigen-presenting cells, including induction of MHC and ICAM-1 expression and production of IL-6. Finally, a model is presented which provides a new view of the initiation and perpetuation of autoimmune beta-cell destruction in Type I diabetes.
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PMID:A new view of the beta cell as an antigen-presenting cell and immunogenic target. 197 Nov 74

An early molecular event in the evolution of insulin-dependent diabetes in humans and NOD mice appears to involve the interaction of MHC class II molecules, beta-cell autoantigen-derived peptides, and receptor molecules of helper T lymphocytes. To examine the influence of T-lymphocyte-receptor beta-genes on the development of beta-cell autoimmunity, (NOD x NZW)F1 x NOD backcrossed (BC) mice were studied for the development of insulitis, because insulitis is the pathognomonic histological lesion of autoimmune diabetes. Heterozygosity for H-2nod was permissive for the development of pancreatic interstitial inflammation and peri-islet insulitis, whereas homozygosity for H-2nod was highly associated with insulitis. However, (NOD x NZW)F1 x NOD BC mice developed insulitis regardless of homozygosity or heterozygosity for T-lymphocyte receptor beta nod. Therefore, in our study, T-lymphocyte receptor beta nod did not function as an autosomal-recessive beta-cell autoimmunity gene.
Diabetes 1990 Aug
PMID:Immunogenetic analysis of beta-cell autoimmunity in NOD mice. Relationship of insulitis to T-lymphocyte-receptor beta nod and A beta nod genes. 197 74

Recent studies in nonobese diabetic mice have implicated the autoimmune destruction of pancreatic islet cells with immunity to a beta cell protein cross-reactive to Mycobacterium tuberculosis heat shock protein 65 (hsp 65). Therefore, our studies examined serological immunity to islet cell hsp in humans with insulin-dependent diabetes (IDD). Heat shock of human islet cells in vitro markedly increased the synthesis of proteins of 72,000, 75,000, and 90,000 Mr. No autoantibodies reactive to these hsp, nor to the constituently expressed islet cell hsp 65 protein (identified as 60,000 Mr) were observed in IDD patients. The islet cell 64,000-Mr autoantigen and hsp 65 proteins were physiologically and immunocompetitively distinct. These experiments do not support the hypothesis that IDD in humans is associated with autoimmunity to islet cell heat shock proteins.
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PMID:No evidence for serological autoimmunity to islet cell heat shock proteins in insulin dependent diabetes. 199 54


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