The N363S polymorphism in the glucocorticoid receptor gene is associated with overweight in subjects with type 2 diabetes mellitus

The human obesity gene map: the 2005 update

This paper presents the 12th update of the human obesity gene map, which incorporates published results up to the end of October 2005. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTL) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2005, 176 human obesity cases due to single-gene mutations in 11 different genes have been reported, 50 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 244 genes that, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 408. The number of human obesity QTLs derived from genome scans continues to grow, and we now have 253 QTLs for obesity-related phenotypes from 61 genome-wide scans. A total of 52 genomic regions harbor QTLs supported by two or more studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably, with 426 findings of positive associations with 127 candidate genes. A promising observation is that 22 genes are each supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. The electronic version of the map with links to useful publications and relevant sites can be found at http://obesitygene.pbrc.edu.

Corticosteroid receptor genetic polymorphisms and stress responsivity

A fundamental question in the neuroendocrinology of stress-related psychopathology is why some individuals flourish and others perish under similar adverse conditions. In this contribution we focus on the variants of mineralocorticorticoid (MR) and glucocorticoid receptors (GR) that operate in balance and coordinate behavioral, autonomic, and neuroendocrine response patterns involved in homeostasis and health. In the GR-gene, three single nucleotide polymorphism (SNPs) have been associated with changes in metabolic profile and cardiovascular parameters: the ER22/23EK with a favorable and the N363S and the Bcl1 with a more adverse profile. Importantly, the N363S and the Bcl1 are found to increase cortisol responses to a psychosocial stressor. As a result, the whole body will suffer from overexposure with possible adverse effects on metabolism, cardiovascular control, immune function, and behavior. Also in the MR gene, variants are being identified that are associated with dysregulated autonomic, behavioral, and neuroendocrine responses. The data suggest that these MR and GR variants contribute to individual differences in resilience and vulnerability to stressors, and that these receptors therefore are potential drug targets for recovery of homeostasis and health.

The N363S polymorphism of the glucocorticoid receptor and metabolic syndrome factors in men

OBJECTIVE

To test the associations between the N363S polymorphism of the glucocorticoid receptor gene (NR3C1) and factors related to the metabolic syndrome in middle-aged men with and without juvenile-onset obesity.

RESEARCH METHODS AND PROCEDURES

This study included two groups of middle-aged men, who were originally identified at 20 years of age at the draft boards. One group (n = 208; age, 48 +/- 6 years) was selected on the basis of juvenile-onset obesity (BMI > or = 31 kg/m(2)). The other group consisted of mainly nonobese men randomly sampled from the same population in parallel with the obese men (n = 299; age, 50 +/- 7 years). The subjects were genotyped for the N363S polymorphism by polymerase chain reaction-restriction fragment length polymorphism. Body composition was measured by DXA. Glucose metabolism was evaluated by an oral glucose tolerance test, and the Matsudas index was calculated as a proxy for insulin sensitivity. Serum triglycerides and total and high-density lipoprotein-cholesterol were measured in the fasting state.

RESULTS

Among the men with juvenile-onset obesity, carriers (n = 17) of the 363S allele had a lower whole body fat percentage, after accounting for differences in BMI and higher Matsudas index, compared with the noncarriers. The difference in Matsudas index lost statistical significance after the difference in body fat was accounted for. In the randomly sampled men, these variables did not relate to genotype. No relationship between carriers and noncarriers was found in body fat distribution or serum lipids.

DISCUSSION

This study suggests that, in men developing obesity early in life, the 363S allele is associated with less adiposity at a given BMI, leading to higher insulin sensitivity.

Microarray profiling of isolated abdominal subcutaneous adipocytes from obese vs non-obese Pima Indians: increased expression of inflammation-related genes

AIMS/HYPOTHESIS

Obesity increases the risk of developing major diseases such as diabetes and cardiovascular disease. Adipose tissue, particularly adipocytes, may play a major role in the development of obesity and its comorbidities. The aim of this study was to characterise, in adipocytes from obese people, the most differentially expressed genes that might be relevant to the development of obesity.

METHODS

We carried out microarray gene profiling of isolated abdominal subcutaneous adipocytes from 20 non-obese (BMI 25+/-3 kg/m2) and 19 obese (BMI 55+/-8 kg/m2) non-diabetic Pima Indians using Affymetrix HG-U95 GeneChip arrays. After data analyses, we measured the transcript levels of selected genes based on their biological functions and chromosomal positions using quantitative real-time PCR.

RESULTS

The most differentially expressed genes in adipocytes of obese individuals consisted of 433 upregulated and 244 downregulated genes. Of these, 410 genes could be classified into 20 functional Gene Ontology categories. The analyses indicated that the inflammation/immune response category was over-represented, and that most inflammation-related genes were upregulated in adipocytes of obese subjects. Quantitative real-time PCR confirmed the transcriptional upregulation of representative inflammation-related genes (CCL2 and CCL3) encoding the chemokines monocyte chemoattractant protein-1 and macrophage inflammatory protein 1alpha. The differential expression levels of eight positional candidate genes, including inflammation-related THY1 and C1QTNF5, were also confirmed. These genes are located on chromosome 11q22-q24, a region with linkage to obesity in the Pima Indians.

CONCLUSIONS/INTERPRETATION

This study provides evidence supporting the active role of mature adipocytes in obesity-related inflammation. It also provides potential candidate genes for susceptibility to obesity.

A psychobiological perspective on genetic determinants of hypothalamus-pituitary-adrenal axis activity

From the perspective of psychobiological stress research we present a brief overview of findings documenting a significant impact of genetic factors on the activity of the hypothalamus-pituitary-adrenal (HPA) axis. Quantitative genetic studies in twins as well as association studies, primarily on polymorphisms in the glucocorticoid receptor gene, are depicted. Recent findings suggest that the collaboration of psychobiology and molecular genetics is a promising interdisciplinary approach that will significantly contribute to the understanding of the mechanisms underlying the link between stress, the HPA axis, and HPA-related clinical states.

The genetics of human obesity

Obesity is an important cause of morbidity and mortality in developed countries, and is also becoming increasingly prevalent in the developing world. Although environmental factors are important, there is considerable evidence that genes also have a significant role in its pathogenesis. The identification of genes that are involved in monogenic, syndromic and polygenic obesity has greatly increased our knowledge of the mechanisms that underlie this condition. In the future, dissection of the complex genetic architecture of obesity will provide new avenues for treatment and prevention, and will increase our understanding of the regulation of energy balance in humans.

Characterization of a promoter polymorphism in the glucocorticoid receptor gene and its relationship to three other polymorphisms

OBJECTIVE

Sensitivity to glucocorticoids within the normal population is highly variable and partly determined by polymorphisms in the glucocorticoid receptor (GR) gene (NR3C1). We investigated the exact sequence alteration of a TthIIII polymorphism in the GR gene, whether it is associated with glucocorticoid sensitivity, and its relationship to 3 polymorphisms of the GR gene (N363S, BclI, ER22/23EK).

DESIGN

Two dexamethasone (DEX) suppression tests were performed with 1 and 0.25 mg DEX, respectively.

PATIENTS

We genotyped a random subgroup of 209 participants of the Rotterdam Study, a population-based study in the elderly.

MEASUREMENTS

Anthropometric parameters, cortisol, insulin and glucose levels, and lipid concentrations were measured.

RESULTS

We identified the TthIIII polymorphism as a C to T mutation, 3807 bp upstream from the mRNA start site. We found 39.7% CC-carriers, 44.5% CT-carriers, and 15.8 % TT-carriers. No differences were found between TthIIII genotypes in sensitivity to DEX, baseline cortisol, insulin, glucose or cholesterol levels, or in anthropometric variables. However, all ER22/23EK-carriers also carried the TthIIII T-allele, and carriers of both these polymorphisms had a significantly smaller cortisol suppression after 1 mg DEX, lower fasting insulin levels, and lower total and low-density lipoprotein (LDL) cholesterol levels than TthIIII T carriers without the ER22/23EK variant and noncarriers. No interaction was found between the TthIIII variant and N363S or BclI polymorphisms.

CONCLUSIONS

The TthIIII polymorphism is not functional by itself. However, the ER22/23EK polymorphism is without exception linked to the TthIIII T polymorphism and this haplotype is associated with a relative resistance to glucocorticoids, and a healthy metabolic profile.