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)

We investigated the cellular mechanism(s) of insulin resistance associated with non-insulin-dependent diabetes mellitus (NIDDM) using adipocytes isolated from non-obese, insulin-resistant type II diabetic Goto-Kakizaki (GK) rats, a well-known genetic rat model for type II diabetic humans. In adipocytes isolated from control rats, insulin (5 nmol/L) stimulated particulate serine/threonine protein phosphatase-1 (PP-1) activity (56% increase over the basal value after 5 minutes). In contrast, adipocytes from diabetic GK rats exhibited a 32% decrease in basal (P < .05) and a 65% decrease in insulin-stimulated PP-1 activity compared with values in control Wistar rats. Conversely, cytosolic PP-2A activity was elevated in diabetic GK rats in the basal state (twofold increase v controls, P < .05). Insulin treatment resulted in a 50% to 60% inhibition in PP-2A activity in control rats, but failed to inhibit PP-2A activity in diabetic GK rat adipocytes. The defects in PP-1/PP-2A activation/inactivation were accompanied by inhibition of insulin's effect on mitogen-activated protein kinase (MAPK) activation. In addition, insulin-stimulated tyrosine phosphorylation of insulin receptor (IR) substrate-1 (IRS-1) was decreased more than 90% compared with control values, while a twofold increase in basal IRS-1 phosphorylation status was observed in diabetic GK rats. The abnormalities in IRS-1 phosphorylation were accompanied by a severe impairment of insulin-mediated targeting of the Grb2/Sos complex to the plasma membrane. We conclude that (1) a rapid activation of PP-1 along with concomitant inhibition of cytosolic PP-2A may be important in the mechanism of insulin action in a normal cell, and (2) the resistance to insulin in terms of glucose uptake and glycogen synthesis observed in diabetic GK rats is partly due to defective regulation of PP-1, PP-2A, and MAPK caused by multiple defects in the upstream insulin signaling components (IRS-1/phosphatidylinositol-3-kinase [PI3-kinase] and Grb2/Sos) that participate in insulin-mediated activation of PP-1 and inactivation of PP-2A.
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PMID:Altered regulation of insulin signaling components in adipocytes of insulin-resistant type II diabetic Goto-Kakizaki rats. 944 Apr 78

We have previously developed a mouse model of insulin-resistant diabetes by targeted inactivation of the insulin receptor gene. During studies of gene expression in livers of insulin receptor-deficient mice, we identified a novel cDNA, which we have termed sirm (Son of Insulin Receptor Mutant mice). sirm is largely, albeit not exclusively, expressed in insulin-responsive tissues. Insulin is a potent modulator of sirm expression, and sirm mRNA levels correlate with tissue sensitivity to insulin. The product of the sirm gene is a serine/threonine-rich protein with several proline-rich motifs and an NPNY motif, conforming to the consensus sequence recognized by the phosphotyrosine binding domains of insulin receptor substrate and Shc proteins. However, Sirm bears no extended homologies with other known proteins. Based on the sequences of the proline-rich domains, we sought to determine whether Sirm binds to the SH3 domains of FYN and Grb-2. We demonstrate here that Sirm binds to FYN and Grb-2 in 3T3-L1 adipocytes and that insulin treatment results in the dissociation of the Sirm.FYN and Sirm.Grb-2 complexes. We also show that Sirm is a substrate for the kinase activity of FYN in vitro. Based on the patterns of expression of sirm, its regulation by insulin, and the interactions with molecules in the insulin signaling pathway, we surmise that Sirm plays a role in modulating tissue sensitivity to insulin.
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PMID:Identification of sirm, a novel insulin-regulated SH3 binding protein that associates with Grb-2 and FYN. 950 6

Glucagon-like peptide 1 (GLP-1) has great potential in diabetes therapy due to its glucose-dependent stimulation of insulin secretion, but this is limited by its rapid degradation, primarily by dipeptidyl peptidase IV. Four analogues, N-terminally substituted with threonine, glycine, serine or alpha-aminoisobutyric acid, were synthesised and tested for metabolic stability. All were more resistant to dipeptidyl peptidase IV in porcine plasma in vitro, ranging from a t1/2 of 159 min (Gly8 analogue) to undetectable degradation after 6 h (Aib8 analogue; t1/2 for GLP-1 (7-36) amide, 28 min). During i. v. infusion in anaesthetised pigs, over 50% of each analogue remained undegraded compared to 22.7 % for GLP-1 (7-36) amide. In vivo, analogues had longer N-terminal t1/2 (intact peptides: means, 3.3-3.9 min) than GLP-1 (7-36) amide (0.9 min; p < 0.01), but these did not exceed the C-terminal t1/2 (intact plus metabolite: analogues, 3.5-4.4 min; GLP-1 (7-36) amide, 4.1 min). Analogues were assessed for receptor binding using a cell line expressing the cloned receptor, and for ability to stimulate insulin or inhibit glucagon secretion from the isolated perfused porcine pancreas. All bound to the receptor, but only the Aib8 and Gly8 analogues had similar affinities to GLP-1 (7-36) amide (IC50; Aib8=0.45 nmol/l; Gly8=2.8 nmol/l; GLP-1 (7-36) amide=0.78 nmol/l). All analogues were active in the isolated pancreas, with the potency order reflecting receptor affinities (Aib8 > Gly8 > Ser8 > Thr8). N-terminal modification of GLP-1 confers resistance to dipeptidyl peptidase IV degradation. Such analogues are biologically active and have prolonged metabolic stability in vivo, which, if associated with greater potency and duration of action, may help to realise the potential of GLP-1 in diabetes therapy.
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PMID:Dipeptidyl peptidase IV resistant analogues of glucagon-like peptide-1 which have extended metabolic stability and improved biological activity. 954 Nov 66

The molecular mechanism by which some, but not all, variants of encephalomyocarditis (EMC) virus selectively infect pancreatic beta-cells in mice and induce IDDM has been an enigma for more than a decade. We report here that the binding site of the EMC viral capsid protein VP1 determines viral diabetogenicity. Recombinant chimeric EMC viruses containing threonine, serine, proline, aspartic acid, or valine at position 152 of the major capsid protein VP1 bind poorly to beta-cells. In contrast, recombinant chimeric EMC viruses containing alanine or glycine at position 152 of the VP1 bind efficiently to and infect beta-cells, resulting in the development of diabetes. Three-dimensional molecular modeling reveals that the van der Waals interactions are greater and the residues surrounding position 152 of the VP1 are more closely packed in recombinant chimeric viruses containing threonine, serine, proline, aspartic acid, or valine at position 152 than in recombinant chimeric viruses containing alanine or glycine at the same position. Our studies reveal that the surface areas surrounding alanine or glycine at position 152 of the VP1 are more accessible, thus increasing the availability of the binding sites for attachment to beta-cell receptors and resulting in viral infection and the development of diabetes.
Diabetes 1998 Apr
PMID:Determination of encephalomyocarditis viral diabetogenicity by a putative binding site of the viral capsid protein. 956 90

Mutations of the hepatocyte nuclear factor-1 alpha (HNF1 alpha) gene are an important cause of autosomal dominant diabetes with onset before age 25 yr [maturity-onset diabetes of the young (MODY)], and some regions of the HNF1 alpha gene appear to be hot spots for mutations. To evaluate the role of HNF1 alpha in the more common familial type 2 diabetes, we studied 62 families of Northern European origin by linkage analysis and molecular screening. Linkage was rejected under dominant models consistent with either late-onset type 2 diabetes or early-onset dominant diabetes. We used single strand conformation polymorphism analysis to screen 53 diabetic members of 36 families who reported diabetes diagnosed before age 40 yr, 9 members of 2 Utah families with typical MODY, and 24 additional members of families with possible linkage. One MODY family showed the previously reported frameshift mutation (P291fsinsC) in exon 4. Among the individuals with more typical type 2 diabetes, we identified the previously reported common polymorphisms, a new intronic polymorphism, and 3 common amino acid variants. We also identified 2 novel missense mutations that segregated with type 2 diabetes in 1 family each: lysine for glutamic acid substitution at codon 619 in exon 10 (E619K), and an arginine for threonine substitution at codon 537 in exon 8 (R537T) in a second family. The exon 8 mutation showed relatively low penetrance, and the role in this family remains uncertain. No coding mutations were identified in the family members screened on the basis of linkage but without early-onset diabetes. Although HNF1 alpha mutations are not a common cause of familial type 2 diabetes, they may account for 5% of families in which at least 1 member has onset of type 2 diabetes before age 40 yr. Incomplete penetrance and a high sporadic frequency make linkage an inefficient screening tool.
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PMID:Linkage and molecular scanning analyses of MODY3/hepatocyte nuclear factor-1 alpha gene in typical familial type 2 diabetes: evidence for novel mutations in exons 8 and 10. 962 39

Uncoupling protein 2 (UCP2), a member of the family of mitochondrial carrier proteins, has been implicated in the control of whole-body energy balance. The coding region of the human UCP2 gene has now been shown to comprise six exons, and the sequences of the exon-intron boundaries were determined. With the use of this sequence information, 25 Japanese patients with obesity and noninsulin-dependent diabetes mellitus (NIDDM) and 25 subjects with simple obesity were screened for mutations in the entire coding region of UCP2 by PCR and single-strand conformation polymorphism analysis. Two nucleotide polymorphisms resulting in Ala55 --> Val and Ala232 --> Thr substitutions were detected. With the use of PCR and restriction fragment length polymorphism analysis, the allele frequencies for each of these polymorphisms were determined in 210 Japanese patients with NIDDM, 42 obese individuals, and 218 normal control subjects. The frequency of the Val55 allele did not differ significantly among the NIDDM group (46.0%), the obesity group (48.8%), and the normal control group (48.4%). The Thr232 allele was detected in only three subjects, who were heterozygotes and in the NIDDM group (allele frequency, 0.7%). However, expression in yeast of the human wild-type UCP2 protein and UCP2 containing Thr232 revealed no difference in functional activity. These results indicate that the Ala55 --> Val and Ala232 --> Thr variants of UCP2 do not play an important role in the pathogenesis of NIDDM or obesity in the Japanese population.
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PMID:Molecular screening of uncoupling protein 2 gene in patients with noninsulin-dependent diabetes mellitus or obesity. 970 50

Mild hyperglycaemia is a common finding during minor illness in children. The differential diagnosis includes maturity onset diabetes of the young (MODY), which can be a difficult diagnosis to make clinically. As most genes resulting in MODY have been identified, it is possible to make a firm diagnosis using mutation detection. A case is reported of a 4 year old girl in whom a diagnosis of MODY2 was established by the finding of a heterozygous missense mutation in exon 7 of the glucokinase gene, resulting in the substitution at codon 259 of alanine by threonine (A259T). Observations from other glucokinase families suggest that hyperglycaemia in this child is likely to be stable and will not require intensive medical follow up, whereas other forms of MODY (1, 3, and 4) might carry a different prognosis.
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PMID:Genetic testing for maturity onset diabetes of the young in childhood hyperglycaemia. 971 13

Heroin, like morphine, given intracerebroventricularly produces analgesia by acting on mu opioid receptors in most mice. In contrast, in Swiss Webster mice, heroin has the unusual property of acting on brain delta opioid receptors whereas morphine still acts on mu receptors. The literature indicates that in diabetic mice and rats, the mu agonist potency of morphine is diminished while that to a delta receptor agonist is enhanced. The purpose of the present study was to determine if the response to heroin occurred through a delta receptor in the brain of streptozotocin-induced diabetic Sprague-Dawley rats. One week after a cannula was surgically implanted in the lateral ventricle, diabetes was induced by intravenous administration of 55 mg/kg of streptozotocin. Three days later the receptor selectivity of intraventricular heroin in the tail flick test was determined by coadministration of opioid antagonists. In nondiabetic rats, a rightward shift in the dose response curve for heroin was produced by naloxone. D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-ThrNH2, a more mu receptor selective antagonist given in a single dose experiment, also inhibited heroin action. Thus, heroin acted on mu receptors. In diabetic rats, intracerebroventricular naltrindole, but not naloxone nor CTOP, inhibited the heroin response and indicated a delta agonist action for heroin. Inhibition by intrathecal yohimbine of the mu (nondiabetic) and bicuculline of the delta response (diabetic) suggested spinal alpha2-adrenergic and GABA(A) receptor mediation, respectively, for the descending systems. In conclusion, the response to heroin was changed from mu in nondiabetic rats to a delta receptor action in diabetic rats. Understanding the basis for this change in receptor selectivity of heroin could provide an important avenue for investigating determinants of opioid receptor function.
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PMID:Heroin acts on delta opioid receptors in the brain of streptozocin-induced diabetic rats. 971 77

Noninsulin-dependent diabetes mellitus (NIDDM), a major health care problem in the Western world, is a disease typified by a relative deficiency of insulin, leading to vast derangements in glucose and lipid homeostasis with disastrous vascular complications. Despite immense research efforts aimed at a clear understanding of the etiology of this complex disease, the molecular mechanisms causing the disorder still remain elusive. This article reviews extant data from recent publications implicating novel signal transduction pathways as important regulators of the insulin stimulus-secretion coupling in the pancreatic beta-cell. The significance of nitric oxide and serine/threonine protein phosphatases, and their inactivation by insulin secretagogues, glucose metabolites, ATP, GTP, glutamate, and inositol hexaphosphate in this arena is scrutinized. Additionally, also presented is the growing concept that an important signal for insulin secretion may reside in the inextricable interplay between glucose and lipid metabolism, specifically the generation of malonyl-CoA, which inhibits carnitine palmitoyltransferase 1 with the attendant accumulation of long-chain acyl CoA esters. Moreover, attention is directed towards novel intracellular actions of hypoglycemic sulfonylureas in the beta-cell. Finally, the importance of "lipotoxicity" and aberrations in glucose uptake and metabolism in beta-cell dysfunction is given consideration. Future research efforts should aim at further characterization of effects of second messengers on protein phosphorylation elements in beta-cells. Additionally, long-term regulation by glucose and the diabetic state (e.g., fatty acids and ketones) on beta-cell protein phosphatases, pyruvate dehydrogenase, and carnitine palmitoyltransferase 1 needs to be explored in greater depth. Clearly, the detrimental impact of diabetic hyperlipidemia on beta-cell function has been a relatively neglected area, but futu re pharmacological approaches directed at preventing lipotoxicity may prove beneficial in the treatment of diabetes.
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PMID:Aspects of novel sites of regulation of the insulin stimulus-secretion coupling in normal and diabetic pancreatic islets. 979 25

Protein kinases C are a family of serine threonine protein kinases that play key roles in extracellular signal transduction. Inappropriate activation of protein kinase C has been implicated in the pathophysiology of many diseases, including diabetes mellitus. Indeed, protein kinase C activation may contribute not only to the pathogenesis of diabetic complications such as nephropathy and retinopathy, but also to insulin resistance. Growing awareness that protein kinase C isoforms subserve specific subcellular functions has led to the development of isoform-specific inhibitors, which may be useful investigational tools and therapeutic agents for attenuating the effects of inappropriate protein kinase C activity. Here we review the role played by protein kinases C in diabetic nephropathy and the recent progress that has been made to modulate its activity using specific inhibitors.
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PMID:Protein kinases C: potential targets for intervention in diabetic nephropathy. 981 5


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