The E23K variant of Kir6.2 associates with impaired post-OGTT serum insulin response and increased risk of type 2 diabetes.

The E23K polymorphism of the pancreatic beta-cell ATP-sensitive K(+) (K(ATP)) channel subunit Kir6.2 (KCNJ11) is associated with type 2 diabetes in whites, and a recent in vitro study of the E23K variant suggests that the association to diabetes might be explained by a slight inhibition of serum insulin release. In a study comprising 519 unrelated glucose-tolerant subjects, we addressed the question as to whether the E23K variant was related to reduced serum insulin release during an oral glucose tolerance test (OGTT).

Variants within the calpain-10 gene on chromosome 2q37 (NIDDM1) and relationships to type 2 diabetes, insulin resistance, and impaired acute insulin secretion among Scandinavian Caucasians.

Variations in the calpain-10 gene (CAPN10) have been identified among Mexican-Americans, and an at-risk haplotype combination (112/121) defined by three polymorphisms, UCSNP-43, -19, and -63, confers increased risk of type 2 diabetes. Here we examine the three polymorphisms in 1,594 Scandinavian subjects, including 409 type 2 diabetic patients, 200 glucose-tolerant control subjects, 322 young healthy subjects, 206 glucose-tolerant offspring of diabetic patients, and 457 glucose-tolerant 70-year-old men. The frequency of the 112/121 combination was not significantly different in 409 type 2 diabetic subjects compared with 200 glucose-tolerant control subjects (0.

Genetic evidence that HNF-1alpha-dependent transcriptional control of HNF-4alpha is essential for human pancreatic beta cell function.

Mutations in the genes encoding hepatocyte nuclear factor 4alpha (HNF-4alpha) and HNF-1alpha impair insulin secretion and cause maturity onset diabetes of the young (MODY). HNF-4alpha is known to be an essential positive regulator of HNF-1alpha. More recent data demonstrates that HNF-4alpha expression is dependent on HNF-1alpha in mouse pancreatic islets and exocrine cells.

Mutation analysis of peroxisome proliferator-activated receptor-gamma coactivator-1 (PGC-1) and relationships of identified amino acid polymorphisms to Type II diabetes mellitus.

Aim/hypothesis: This study aimed to investigate if variability in the peroxisome proliferator-activated receptor-gamma coactivator-1 (PGC-1) gene is associated with Type II (non-insulin-dependent) diabetes mellitus.

Methods: The PGC-1 gene was examined in 53 Type II diabetic patients applying single strand conformational polymorphism analysis followed by nucleotide sequencing. Identified variants were genotyped in an association study comprising 483 Type II diabetic patients and 216 glucose-tolerant control subjects.

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.

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.

The Asn363Ser variant of the glucocorticoid receptor gene is not associated with obesity or weight gain in Danish men.

Objective: Testing association of the Asn363Ser variant of the glucocorticoid gene with measures of obesity and weight gain.

Subjects: 741 obese subjects (BMI > or = 31 kg/m(2) at selection) and 854 random control subjects from the same population, examined at draft board examination and after on average 27.4+/- y.

Studies of the variability of the hepatocyte nuclear factor-1beta (HNF-1beta / TCF2) and the dimerization cofactor of HNF-1 (DcoH / PCBD) genes in relation to type 2 diabetes mellitus and beta-cell function.

Mutations in the homeodomain-containing transcription factor hepatocyte nuclear factor-1beta (HNF-1beta) are known to cause a rare subtype of maturity-onset diabetes of the young (MODY5), which is associated with early-onset progressive non-diabetic renal dysfunction. To investigate whether mutations in HNF-1 are implicated in the pathogenesis of MODY or late-onset diabetes with and without nephropathy in Danish Caucasians we examined the HNF-1beta (TCF2) and the dimerization cofactor of HNF-1 (DCoH, PCBD) genes for mutations in 11 MODY probands, 28 type 2 diabetic patients with nephropathy, and 46 type 2 diabetic patients with an impaired beta-cell function by combined single-strand conformation polymorphism (SSCP) and heteroduplex analysis. Analysis of the promoter and nine exons including intron-exon boundaries of the HNF-1beta gene revealed one novel silent polymorphism and three previously reported intronic variants.

Studies of the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene in relation to insulin sensitivity among glucose tolerant caucasians.

Aims/hypothesis: We examined whether the Pro12-Ala polymorphism of the human peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene was related to altered insulin sensitivity among glucose-tolerant subjects or a lower accumulated incidence or prevalence of IGT and Type II (non-insulin-dependent) diabetes mellitus among Scandinavian Caucasians.

Methods: The Pro12Ala polymorphism was examined using PCR-RFLP Whole-body insulin sensitivity measured under hyperinsulinaemic-euglycaemic conditions was estimated in a population-based sample of 616 glucose tolerant Swedish Caucasian men at age 70. In addition, insulin sensitivity index was measured using IVGTT and Bergman minimal modelling in a population-based sample of 364 young healthy Danish Caucasians.

Studies of genetic variability of the glucose transporter 2 promoter in patients with type 2 diabetes mellitus.

This study was performed to test the hypothesis that genetic variation in the promoter of the glucose transporter 2 (GLUT2) might predispose to prediabetic phenotypes or type 2 diabetes. A total of 1611 bp comprising the minimal promoter region of the GLUT2 gene were examined by combined single-strand conformational polymorphism and heteroduplex analysis followed by direct sequencing of identified variants on genomic DNA from 96 randomly recruited Danish type 2 diabetic patients. We identified 4 nucleotide variants, -447g-->a, -149c-->a, -122t-->c, and -44g-->a.

Studies of variability in the PTEN gene among Danish caucasian patients with Type II diabetes mellitus.

Aim/hypothesis: Phosphatase and tensin homologue deleted from chromosome ten (PTEN) has recently been characterized as a novel member in the expanding network of proteins regulating the intracellular effects of insulin. By dephosphorylation of phosphatidyl-inositol-(3, 4, 5)-trisphosphate (PIP3) the PTEN protein regulates the insulin-dependent phosphoinositide 3-kinase (PI3K) signalling cassette and accordingly might function as a regulator of insulin sensitivity in skeletal muscle and adipose tissue. In this study we tested PTEN as a candidate gene for insulin resistance and late-onset Type II (non-insulin-dependent) diabetes mellitus in a Danish Caucasian population.

Studies of the synergistic effect of the Trp/Arg64 polymorphism of the beta3-adrenergic receptor gene and the -3826 A-->G variant of the uncoupling protein-1 gene on features of obesity and insulin resistance in a population-based sample of 379 young Danish subjects.

This study examined whether the simultaneous presence of the previously identified Trp/Arg64 polymorphism of the beta3-adrenergic receptor (BAR) gene and the -3826 A-->G nucleotide variant of the uncoupling protein-1 (UCP1) gene are associated with obesity, insulin resistance, or alterations in size at birth in a Danish study population comprising 379 unrelated young Caucasian subjects. All study participants underwent an iv glucose tolerance test with addition of tolbutamide after 20 min. In addition, a number of biochemical and anthropometric measures were performed on each subject.

The K121Q variant of the human PC-1 gene is not associated with insulin resistance or type 2 diabetes among Danish Caucasians.

The human plasma-cell membrane differentiation antigen-1 (PC-1) has been shown to inhibit insulin receptor tyrosine kinase activity. Recently, a K121Q polymorphism in the human PC-1 gene was found in a Sicilian population and was shown to be strongly associated with insulin resistance. The objectives of the present investigation were to examine in the Danish Caucasian population whether the K121Q variant was associated with type 2 diabetes or, in glucose-tolerant subjects, with impaired whole-body insulin sensitivity.

The c-Jun amino-terminal kinase pathway is preferentially activated by interleukin-1 and controls apoptosis in differentiating pancreatic beta-cells.

To characterize the differentiation events that selectively target insulin-producing cells to interleukin (IL)-1beta-induced apoptosis, we studied IL-1beta signaling via mitogen-activated protein kinase (MAPK) and stress-activated protein kinase in 2 pancreatic endocrine cell lines. We studied the glucagon-secreting AN-glu cell line and the insulin and the islet amyloid polypeptide-producing beta-cell line (AN-ins cells), which is derived by stable transfection of AN-glu cells with the transcription factor pancreatic duodenal homeobox factor-1. AN-ins cells were more sensitive to the cytotoxic action of IL-1beta.

Variability of the insulin receptor substrate-1, hepatocyte nuclear factor-1alpha (HNF-1alpha), HNF-4alpha, and HNF-6 genes and size at birth in a population-based sample of young Danish subjects.

Reduced size at birth has been proposed to be a risk factor for insulin resistance and type 2 diabetes. It is, however, not known whether this association is explained by unfavorable intrauterine environment or by specific susceptibility genotypes predisposing for both reduced fetal growth and insulin resistance and type 2 diabetes. The present study was performed to evaluate whether previously identified amino acid polymorphisms of genes that from animal models have been suggested to play important roles during fetal development are associated with alterations in size at birth.

The -238 and -308 G-->A polymorphisms of the tumor necrosis factor alpha gene promoter are not associated with features of the insulin resistance syndrome or altered birth weight in Danish Caucasians.

Recently, two G-->A polymorphisms at positions -308 and -238, in the promoter of the tumor necrosis factor alpha (TNF-alpha) gene, have been identified. These variants have, in different ethnic groups, been linked to estimates of insulin resistance and obesity. The objective of the present study was to investigate whether these genetic variants of TNF-alpha were associated with features of the insulin resistance syndrome or alterations in birth weight in two Danish study populations comprising 380 unrelated young healthy subjects and 249 glucose-tolerant relatives of type 2 diabetic patients, respectively.

Studies of the variability of the genes encoding the insulin-like growth factor I receptor and its ligand in relation to type 2 diabetes mellitus.

Insulin-like growth factor I (IGF-I) is an important regulator of many aspects of growth, differentiation, and development, and as low birth weight has been associated with impaired glucose tolerance and overt type 2 diabetes in adult life, we considered the genes encoding the IGF-I and the IGF-I receptor (IGF-IR) as candidates for low birth weight, insulin resistance, and type 2 diabetes. Here we report the mutational analysis of the coding regions of the IGF-I and IGF-IR performed on genomic DNA from probands of 82 Danish type 2 diabetic families. No mutations predicting changes in the amino acid sequences of the IGF-I or IGF-IR genes were detected, but several silent and intronic polymorphisms were found.

Interferon-gamma induces interleukin-1 converting enzyme expression in pancreatic islets by an interferon regulatory factor-1-dependent mechanism.

Whereas nitric oxide (NO) production is associated with the toxic effect of cytokines on rodent pancreatic beta-cells, cytokine-induced apoptosis in human islets may occur independently of NO. The cysteine protease interleukin (IL)-1 converting enzyme (ICE) is a key proapoptotic caspase. Our aim was therefore to analyze the effect of cytokines on ICE expression in human, rat, and mouse islets and rat insulinoma cells.

Sequence variants in the human cocaine and amphetamine-regulated transcript (CART) gene in subjects with early onset obesity.

Objective: The cocaine and amphetamine-regulated transcript (CART) is expressed in the brain of rodents and humans, and intracerebroventricular injection of the peptide in rats reduces food intake. The objective of the present study was to chromosomally map the CART gene and to examine the coding region of the gene for variability in obese subjects.

Methods: The coding region of the CART gene was analyzed by single-strand conformation polymorphism analysis in 84 subjects with early onset obesity.

Homozygosity of the Pro12Ala variant of the peroxisome proliferation-activated receptor-gamma2 (PPAR-gamma2): divergent modulating effects on body mass index in obese and lean Caucasian men.

Aims/hypothesis: The objectives of the present investigation were to examine: 1) whether a Pro115Gln variant in the peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) is associated with juvenile-onset obesity among Danish Caucasianmen and 2) whether the relation of a Pro12Ala polymorphism in PPAR-gamma2 with BMI and long-term weight regulation differ between lean and obese subjects within the same cohort.

Methods: The Pro115Gln and Pro112Ala variants were examined using PCR and RFLP in a group of 752 subjects with a Body Mass Index (BMI) of 31.0 kg/m2 or more and in 869 non-obese control subjects.

Discovery of a Met300Val variant in Shc and studies of its relationship to birth weight and length, impaired insulin secretion, insulin resistance, and type 2 diabetes mellitus.

The Shc adaptor proteins corresponding to the 46-, 52-, and 66-kDa isoforms are key transducers of growth promotion and gene expression, which are being phosphorylated by all known receptor tyrosine kinases after stimulation by growth factors such as insulin and insulin-like growth factor I. Several studies have demonstrated a relationship between intrauterine growth retardation and impaired glucose tolerance or type 2 diabetes later in life. It is unclear whether this finding is partially explained by genetic factors.

Mutational analysis of the coding regions of the genes encoding protein kinase B-alpha and -beta, phosphoinositide-dependent protein kinase-1, phosphatase targeting to glycogen, protein phosphatase inhibitor-1, and glycogenin: lessons from a search for genetic variability of the insulin-stimulated glycogen synthesis pathway of skeletal muscle in NIDDM patients.

The finding of a reduced insulin-stimulated glucose uptake and glycogen synthesis in the skeletal muscle of glucose-tolerant first-degree relatives of patients with NIDDM, as well as in cultured fibroblasts and skeletal muscle cells isolated from NIDDM patients, has been interpreted as evidence for a genetic involvement in the disease. The mode of inheritance of the common forms of NIDDM is as yet unclear, but the prevailing hypothesis supports a polygenic model. In the present study, we tested the hypothesis that the putative inheritable defects of insulin-stimulated muscle glycogen synthesis might be caused by genetic variability in the genes encoding proteins shown by biochemical evidence to be involved in insulin-stimulated glycogen synthesis in skeletal muscle.

Mutational analysis of the proopiomelanocortin gene in Caucasians with early onset obesity.

Objective: Mutations in the human gene encoding the polyhormone peptide proopiomelanocortin (POMC) are associated with obesity in rare cases and the gene co-localizes with a reported quantitative trait loci (QTL) for variations in circulating leptin levels and fat mass on human chromosome 2p21. In this study we have used polymerase chain reaction (PCR) and single strand conformation polymorphism (SSCP) analysis, to test whether variations in the human POMC gene are associated with human obesity.

Design And Subjects: Primary mutational analysis was performed on the coding region of the POMC gene and 500 bp of the putative promoter region, by single strand conformational analysis and sequencing, in 56 subjects with juvenile onset obesity (body mass index (BMI) > or = 31 kg/m2 at the draft board examination).

Analysis of the relationship between fasting serum leptin levels and estimates of beta-cell function and insulin sensitivity in a population sample of 380 healthy young Caucasians.

Objective: Circulating leptin levels correlate positively with the degree of obesity and prolonged hyperinsulinaemia increases serum leptin levels. Moreover, insulin secreting beta-cells express functional leptin receptors indicating a functional relationship between leptin and insulin. The aim of this study was to examine the relationship between fasting serum leptin levels and measures of insulin sensitivity and beta-cell function in a population-based sample of 380 young healthy Caucasians.

A novel Phe75fsdelT mutation in the hepatocyte nuclear factor-4alpha gene in a Danish pedigree with maturity-onset diabetes of the young.

Mutations in 5 different genes [the hepatocyte nuclear factor (HNF)-4alpha), glucokinase, HNF-1alpha, insulin promoter factor-1, and HNF-1beta genes] have been shown to cause maturity onset diabetes of the young (MODY). About 50% of all known MODY in Danish Caucasian MODY probands can be explained by mutations in the HNF-1alpha gene (MODY3). To estimate the prevalence of MODY caused by mutations in the HNF-4alpha gene (MODY1), we screened 10 non-MODY3 probands for mutations in the minimal promoter and the 12 exons of the HNF-4alpha gene.

Mutations in the hepatocyte nuclear factor-1alpha gene in Caucasian families originally classified as having Type I diabetes.

Mutations in the hepatocyte nuclear factor-1alpha (HNF-1alpha) gene are the cause of maturity-onset diabetes of the young type 3 (MODY3), which is characterised by a severe impairment of insulin secretion and an early onset of the disease. Also at onset of diabetes some MODY patients show similar clinical symptoms and signs as patients with Type I (insulin-dependent) diabetes mellitus. The objective of this study was to estimate the prevalence of MODY3 patients misclassified as Type I diabetic patients.