Objective. To determine if polymorphisms of the macrophage migration inhibitory factor (MIF) gene are associated with juvenile idiopathic arthritis (JIA).Methods. Denaturing high-performance liquid chromatography was used to screen the MIF gene in 32 UK Caucasian controls and 88 UK Caucasian JIA patients. Ninety-two healthy UK Caucasian controls were then genotyped for each of the polymorphic positions identified. A panel of 526 UK Caucasian JIA patients and 259 UK Caucasian controls were subsequently genotyped for a single-nucleotide polymorphism (SNP) identified in the 5-flanking region of the gene, using SNaPshot ddNTP primer extension and capillary electrophoresis. The functional significance of this polymorphism was also studied using luciferase-based reporter gene assays in human T lymphoblast and epithelial cell lines.Results. A tetranucleotide repeat CATT (5-7) beginning at nucleotide position ؊794 and 3 SNPs at positions ؊173 (G to C), ؉254 (T to C), and ؉656 (C to G) of the MIF gene were identified. No JIA-specific mutations were found. Allele and genotype frequencies differed significantly between the controls and the JIA patients for the MIF-173 polymorphism. Individuals possessing a MIF-173*C allele had an increased risk of JIA (34.8% versus 21.6%) (odds ratio 1.9, 95% confidence interval 1.4-2.7; P ؍ 0.0002). Furthermore, the MIF-173* G and C variants resulted in altered expression of MIF in a cell type-specific manner. Serum levels of MIF were also significantly higher in individuals who carried a MIF-173*C allele (P ؍ 0.04).Conclusion. The ؊173-MIF*C allele confers increased risk of susceptibility to JIA. Our data suggest a cell type-specific regulation of MIF, which may be central to understanding its role in inflammation.Growing interest surrounds the macrophage migration inhibitory factor (MIF) molecule (1). Originally described as a T cell-derived cytokine, MIF is now known to be expressed by many different cell types (for review, see ref.2). MIF has proinflammatory, enzymatic, and hormonal activities (1,3). The molecule is induced by low concentrations of glucocorticoids, which is unusual for a proinflammatory cytokine, and it then acts to
Maternal food restriction is associated with the development of obesity in offspring. This study examined how maternal undernutrition in sheep affects the fetal hypothalamic glucocorticoid receptor (GR) and the appetite-regulating neuropeptides, proopiomelanocortin (POMC) and neuropeptide Y, which it regulates. In fetuses from ewes undernourished from -60 to +30 d around conception, there was increased histone H3K9 acetylation (1.63-fold) and marked hypomethylation (62% decrease) of the POMC gene promoter but no change in POMC expression. In the same group, acetylation of histone H3K9 associated with the hypothalamic GR gene was increased 1.60-fold and the GR promoter region was hypomethylated (53% decrease). In addition, there was a 4.7-fold increase in hypothalamic GR expression but no change in methylation of GR gene expression in the anterior pituitary or hippocampus. Interestingly, hypomethylation of both POMC and GR promoter markers in fetal hypothalami was also identified after maternal undernutrition from -60 to 0 d and -2 to +30 d. In comparison, the Oct4 gene, was hypermethylated in both control and underfed groups. Periconceptional undernutrition is therefore associated with marked epigenetic changes in hypothalamic genes. Increase in GR expression in the undernourished group may contribute to fetal programming of a predisposition to obesity, via altered GR regulation of POMC and neuropeptide Y. These epigenetic changes in GR and POMC in the hypothalamus may also predispose the offspring to altered regulation of food intake, energy expenditure, and glucose homeostasis later in life.
Differences in glucocorticoid (GC) sensitivity may underlie both common diseases (e.g. hypertension) and variability in response to treatment with GCs (e.g. asthma). We tested the potential involvement of the GC receptor (GR) gene in mediating GC sensitivity using haplotype analysis and a low-dose dexamethasone suppression test. Linkage disequilibrium across the GR gene was determined in 216 U.K. Caucasians, and 116 had a 0.25-mg overnight dexamethasone suppression test. Very strong linkage disequilibrium was observed across the GR gene with only four haplotypes accounting for 95% of those observed. Haplotype pattern mining and linear regression analyses independently identified a three-marker haplotype, across intron B, to be significantly associated with low postdexamethasone cortisol (P = 0.03). Carriage of this haplotype occurred in 41% of the individuals with low postdexamethasone cortisol vs. 23% in the combined other quartiles (odds ratio 2.4, 95% confidence interval 0.9-6.3, P = 0.05). This is the first comprehensive, haplotype based analysis of the GR gene. A three-point haplotype, within intron B, is associated with enhanced sensitivity to GCs. This haplotype may help predetermine variation in clinical response to GC therapy and also assist the understanding of diseases related to GC production.
Glucocorticoids (Gcs) are commonly used to treat patients suffering from a wide range of cancers. Their main therapeutic role is based on Gc receptor (GR)-mediated mechanisms that trigger cell death but this varies depending on the cancer type. This review aims to provide an overview of the mechanisms of Gc-induced cell death and more importantly the changes in GR that lead to resistance to Gc treatment in cancer. The three main cancer types, which are susceptible to Gc resistance and therefore loss of Gc-induced apoptotic effects, are acute lymphoblastic leukaemia, osteosarcoma and small-cell lung carcinoma. A common theme is the loss of GR function and/or a downregulation of GR expression which leads to failure of the cell death-inducing effects of Gcs. Loss of GR function is attributed to mutations in the GR gene, and in some cases a dominant-negative effect on any functional GR still present. The downregulation of GR expression can be due to decreased GR promoter activation, increased GR promoter methylation or increased expression of alternative splice isoforms of GR that have decreased transcriptional activity. Understanding the mechanisms behind Gc-triggered apoptosis and the resistance to it in these cancer types will help in further refining treatment regimens for patients and will decrease the chance of relapse caused by Gc-resistant cancer phenotypes.
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