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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin-dependent neonatal diabetes (ND) mellitus is uncommon with a frequency of 1/500,000 neonates in Europe. ND is characterised by hyperglycaemia, very low or undetectable insulin levels associated with intrauterine growth retardation and malformations. HLA haplotypes of juvenile diabetes or autoimmunity are not present in ND patients. Sporadic and familial forms are observed. ND could be persistent (PND) or transient (TND). Diabetes relapses occur in approximately 40% of TND patients. Hypothesis for ND aetiology such as pancreatic or beta pancreatic islets of Langerhans immaturity or abnormalities of pancreas organogenesis are postulated. Different genetic basis underlie transient or permanent forms though their clinical features do not allow to distinguish them. TND may in about 20-30% of the cases be associated with chromosome 6 paternal uniparental disomy. A candidate locus for an imprinted gene is mapped to 6q24. The permanent forms are less understood. Homozygous mutations of the IPF1/PDX1 (MODY4) and of the Glucokinase (GK, MODY2) genes have been reported. The association of a ND with a macroglossia should be a strong indicator for genetic testing. The genetic findings of a paternal disomy uniparental allows the prediction of a transient rather than a permanent form. Mutation in the Glucokinase gene should be sought in an infant with ND whose first degree relatives have glucose intolerance.
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PMID:[Insulin-dependent neonatal and infant diabetes: genetics and physiopathology]. 1208 68

Maturity-onset diabetes of the young (MODY) is a subtype of early-onset diabetes mellitus which is characterized by autosomal dominant inheritance. Several genes are known to induce MODY : HNF4A/MODY1, GCK/MODY2, TCF1/MODY3, IPF1/MODY4, TCF2/MODY5 and NEUROD1/MODY6. We studied a Swiss family with 13 diabetic patients over 3 generations. The average age at diagnosis was 35 +/- 15 years (7 subjects before 30). In addition, 2 individuals had an abnormal oral glucose tolerance. The mutation present in this family was located in the DNA binding domain of HNF4A, a strongly conserved region across almost all species, and segregated in all the MODY patients. Identification of this missense mutation allowed for presymptomatic diagnosis in the younger generations and will improve medical follow-up of the predisposed individuals.
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PMID:Large Family With Maturity-Onset Diabetes of the Young and a Novel V121I Mutation in HNF4A. 1220 96

The pancreatic and duodenal homeobox factor-1 (PDX-1), also known as IDX-1/STF-1/IPF1, a homeodomain-containing transcription factor, plays a central role in regulating pancreatic development and insulin gene transcription. Furthermore, even in adults, PDX-1 is associated with islet neogenesis and differentiation of insulin-producing cells from progenitor cells. Here, we report for the first time that PDX-1 protein can permeate cells due to an Antennapedia-like protein transduction domain sequence in its structure and that transduced PDX-1 functions similarly to endogenous PDX-1; it binds to the insulin promoter and activates its expression. PDX-1 protein can also permeate into isolated pancreatic islets, which leads to stimulation of insulin gene expression. Moreover, PDX-1 protein transduced into cultures of pancreatic ducts, thought to be islet progenitor cells, induces insulin gene expression. These data suggest that PDX-1 protein transduction could be a safe and valuable strategy for enhancing insulin gene transcription and for facilitating differentiation of ductal progenitor cells into insulin-producing cells without requiring gene transfer technology.
Diabetes 2003 Jul
PMID:PDX-1 protein containing its own antennapedia-like protein transduction domain can transduce pancreatic duct and islet cells. 1282 40

Oxidative stress is produced under diabetic conditions and is likely involved in progression of pancreatic beta-cell dysfunction found in diabetes. Possibly caused by low levels of antioxidant enzyme expressions, pancreatic beta-cells are vulnerable to oxidative stress. When beta-cell-derived HIT-T15 cells or isolated rat islets were exposed to oxidative stress, insulin gene expression was markedly decreased. To investigate the significance of oxidative stress in the progression of pancreatic beta-cell dysfunction in type 2 diabetes, we evaluated the effects of antioxidants in diabetic C57BL/KsJ-db/db mice. According to an intraperitoneal glucose tolerance test, the treatment with antioxidants retained glucose-stimulated insulin secretion and moderately decreased blood glucose levels. Histological analyses of the pancreata revealed that the beta-cell mass was significantly larger in the mice treated with the antioxidants, and the antioxidant treatment suppressed apoptosis in beta-cells without changing the rate of beta-cell proliferation. The antioxidant treatment also preserved the amounts of insulin content and insulin mRNA, making the extent of insulin degranulation less evident. As possible mechanism underlying the phenomena, expression of pancreatic and duodenal homeobox factor-1 (also known as IDX-1/STF-1/IPF1), an important transcription factor for the insulin gene, was more clearly visible in the nuclei of islet cells after the antioxidant treatment. Under diabetic conditions, JNK is activated by oxidative stress and involved in the suppression of insulin gene expression. This JNK effect appears to be mediated in part by nucleocytoplasmic translocation of PDX-1, which is also downstream of JNK activation. Taken together, oxidative stress and consequent activation of the JNK pathway are involved in progression of beta-cell dysfunction found in diabetes. Antioxidants may serve as a novel mechanism-based therapy for type 2 diabetes.
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PMID:Role of oxidative stress in pancreatic beta-cell dysfunction. 1512 94

Oxidative stress is induced under diabetic conditions through various pathways, including the electron transport chain in mitochondria and the nonenzymatic glycosylation reaction, and is likely involved in progression of pancreatic beta-cell dysfunction developing in diabetes. beta-Cells are vulnerable to oxidative stress, possibly due to low levels of antioxidant enzyme expression. When oxidative stress was induced in vitro in beta cells, the insulin gene promoter activity and mRNA levels were suppressed, accompanied by the reduced activity of pancreatic and duodenal homeobox factor-1 (PDX-1) (also known as IDX-1/STF-1/IPF1), an important transcription factor for the insulin gene. The suppression of oxidative stress by a potent antioxidant, N-acetyl-l-cysteine or probucol, led to the recovery of insulin biosynthesis and PDX-1 expression in nuclei and improved glucose tolerance in animal models for type 2 diabetes. As a possible cause of this, we recently found that PDX-1 was translocated from the nucleus to the cytoplasm in response to oxidative stress. Furthermore, the addition of a dominant-negative form of c-Jun N-terminal kinase (JNK) inhibited the oxidative stress-induced PDX-1 translocation, suggesting an essential role of JNK in mediating the phenomenon. Taken together, the oxidative stress-mediated activation of the JNK pathway leads to nucleocytoplasmic translocation of PDX-1 and thus is likely involved in the progression of beta-cell dysfunction found in diabetes.
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PMID:Oxidative stress and pancreatic beta-cell dysfunction. 1628 Jun 46

Generation of pancreatic precursor cells in the endoderm is controlled by a network of transcription factors. Hepatocyte nuclear factor-6 (HNF6) is a key player in this network, because it controls the initiation of the expression of pancreatic and duodenal homeobox 1 (Pdx1), the earliest marker of pancreatic precursor cells. To further characterize this network, we have investigated how the expression of HNF6 is controlled in mouse endoderm, by using in vitro and in vivo protein-DNA interaction techniques combined with endoderm electroporation, transgenesis, and gene inactivation in embryos. We delineated Hnf6 regulatory regions that confer expression of a reporter gene in the embryonic endoderm but not in extraembryonic visceral endoderm. HNF6 expression in the embryonic endoderm was found to depend on an intronic enhancer. This enhancer contains functional binding sites for the tissue-specific factors of the forkhead box A and HNF1 families. Among the latter, variant HNF1 (vHNF1)/TCF2, which is expressed before HNF6 in the endoderm, was found to be critical for HNF6 expression. Therefore, the sequential activation of vHNF1, HNF6, and Pdx1 in the endoderm appears to control the generation of pancreatic precursors. This cascade may be used to benchmark in vitro differentiation of pancreatic precursor cells from embryonic stem cells, for cell therapy of diabetes.
Diabetes 2006 Jan
PMID:A vHNF1/TCF2-HNF6 cascade regulates the transcription factor network that controls generation of pancreatic precursor cells. 1638 Apr 77

The transcription factor IPF1/PDX1 plays a crucial role in both pancreas development and maintenance of beta-cell function. Targeted disruption of this transcription factor in beta-cells leads to diabetes, whereas reduced expression levels affect insulin expression and secretion. Therefore, it is essential to determine molecular mechanisms underlying the regulation of this key transcription factor on mRNA levels and, most importantly, on protein levels. Here we show that a minor portion of IPF1/PDX1 is phosphorylated on serine 61 and/or serine 66 in pancreatic beta-cells. This phosphorylated form of IPF1/PDX1 preferentially accumulates following proteasome inhibition, an effect that is prevented by inhibition of glycogen synthase kinase 3 (GSK3) activity. Oxidative stress, which is associated with the diabetic state, (i) increases IPF1/PDX1 Ser61 and/or Ser66 phosphorylation and (ii) increases the degradation rate and decreases the half-life of IPF-1/PDX-1 protein. In addition, we provide evidence that GSK3 activity participates in oxidative stress-induced effects on beta-cells. Thus, this current study uncovers a new mechanism that might contribute to diminished levels of IPF1/PDX1 protein and beta-cell dysfunction during the progression of diabetes.
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PMID:Phosphorylation marks IPF1/PDX1 protein for degradation by glycogen synthase kinase 3-dependent mechanisms. 1640 9

Because impaired insulin secretion is characteristic of type 2 diabetes in Asians, including Japanese, the genes involved in pancreatic beta-cell function are candidate susceptibility genes for type 2 diabetes. We examined the association of variants in genes encoding several transcription factors (TCF1, TCF2, HNF4A, ISL1, IPF1, NEUROG3, PAX6, NKX2-2, NKX6-1, and NEUROD1) and genes encoding the ATP-sensitive K(+) channel subunits Kir6.2 (KCNJ11) and SUR1 (ABCC8) with type 2 diabetes in a Japanese cohort of 2,834 subjects. The exon 16 -3c/t variant rs1799854 in ABCC8 showed a significant association (P = 0.0073), and variants in several genes showed nominally significant associations (P < 0.05) with type 2 diabetes. Although the E23K variant rs5219 in KCNJ11 showed no association with diabetes in Japanese (for the K allele, odds ratio [OR] 1.08 [95% CI 0.97-1.21], P = 0.15), 95% CI around the OR overlaps in meta-analysis of European populations, suggesting that our results are not inconsistent with the previous studies. This is the largest association study so far conducted on these genes in Japanese and provides valuable information for comparison with other ethnic groups.
Diabetes 2006 Aug
PMID:Association studies of variants in the genes involved in pancreatic beta-cell function in type 2 diabetes in Japanese subjects. 1687 4

Although lifestyle and environmental factors influence the prevalence of myocardial infarction, genetic epidemiological studies have suggested that several genetic variants increase the risk for this condition. We have performed a large-scale association study to identify gene polymorphisms for reliable assessment of the genetic risk of myocardial infarction. The study population comprised 3,483 unrelated Japanese individuals (1,913 men; 1,570 women), including 1,192 subjects with myocardial infarction and 2,291 controls. The genotypes for 164 polymorphisms of 137 candidate genes were determined with an oligonucleotide ligation assay based on analysis of fluorescent microspheres with suspension array technology. Multivariable logistic regression analysis with adjustment for age, sex, body mass index, and the prevalence of smoking, hypertension, diabetes mellitus, and hypercholesterolemia revealed that the 677C-->T (Ala222Val) polymorphism of MTHFR, the 1595C-->G (Ser447Stop) polymorphism of LPL, and the -108/3G-->4G polymorphism of IPF1 were significantly associated with the prevalence of myocardial infarction. A stepwise forward selection procedure demonstrated that IPF1, MTHFR, and LPL genotypes significantly affected the prevalence of myocardial infarction. Combined genotype analysis of these polymorphisms yielded a maximum odds ratio of 2.54 for the combined genotype of TT for MTHFR, CC for LPL, and 3G3G for IPF1. The genotypes for MTHFR, LPL, and IPF1 may prove reliable for assessment of genetic risk for myocardial infarction. Determination of the combined genotype for these genes may contribute to primary, personalized prevention of this condition.
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PMID:Assessment of genetic risk for myocardial infarction. 1689 68

Maturity-onset diabetes of the young (MODY) is a monogenic form of diabetes mellitus characterized by autosomal dominant inheritance, early age of onset (often <25 years of age), and pancreatic beta-cell dysfunction. MODY is both clinically and genetically heterogeneous, with six different genes identified to date; glucokinase (GCK), hepatocyte nuclear factor-1 alpha (HNF1A, or TCF1), hepatocyte nuclear factor-4 alpha (HNF4A), insulin promoter factor-1 (IPF1 or PDX1), hepatocyte nuclear factor-1 beta (HNF1B or TCF2), and neurogenic differentiation 1 (NEUROD1). Mutations in the HNF1A gene are a common cause of MODY in the majority of populations studied. A total of 193 different mutations have been described in 373 families. The most common mutation is Pro291fs (P291fsinsC) in the polycytosine (poly C) tract of exon 4, which has been reported in 65 families. HNF4A mutations are rarer; 31 mutations reported in 40 families. Sensitivity to treatment with sulfonylurea tablets is a feature of both HNF1A and HNF4A mutations. The identification of an HNF1A or 4A gene mutation confirms a diagnosis of MODY and has important implications for clinical management.
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PMID:Mutations in the genes encoding the transcription factors hepatocyte nuclear factor 1 alpha (HNF1A) and 4 alpha (HNF4A) in maturity-onset diabetes of the young. 1691 92


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