Expression of <i>IRX3</i> and <i>IRX5</i> in adipose tissue of children and association with <i>FTO</i> risk haplotype and with <i>UCP1</i> expression.

<p>Adipocyte and whole AT expression of <i>IRX3</i> was reduced in obese compared to lean children (A). Adipocyte-specific expression of <i>IRX3</i> and <i>IRX5</i> was significantly increased in lean children carrying the <i>FTO</i> risk haplotype compared to lean children carrying the nonrisk haplotype (B). There were no alterations in <i>IRX3</i> and <i>IRX5</i> expression between <i>FTO</i> haplotype groups in SVF (C) or whole AT (D) of lean children. Obese children did not show differences in <i>IRX3</i> and <i>IRX5</i> expression levels between <i>FTO</i> haplotype groups in any of the analyzed tissues (B-D). Significant differences between <i>FTO</i> nonrisk versus risk haplotype groups were assessed by Student’s <i>t</i>-test and significant <i>p</i>-values are indicated in the barplots.</p

Multiple regression analyses for predictors of adipocyte <i>IRX3/5</i> expression.

<p>Multiple regression analyses for predictors of adipocyte <i>IRX3/5</i> expression.</p

Adipocyte <i>IRX3</i> expression is associated with obesity-related alterations in AT and related clinical traits.

<p>Expression of <i>IRX3</i> but not <i>IRX5</i> was significantly lower in <i>UCP1</i>-positive (18 lean, 19 obese) compared <i>UCP1</i>-negative adipocytes (21 lean, 23 obese) derived from lean, but not of obese children (A). Significant differences between <i>UCP1</i>-positive versus <i>UCP1</i>-negative adipocyte samples were assessed by Student’s <i>t</i>-test and <i>p</i>-values are indicated in the barplots. Protein levels of IRX3 are reduced in adipocyte of obese (n = 4) compared to lean (n = 3) children (B). Expression of <i>IRX3</i> in adipocytes of children was associated with adipocyte diameter (C), macrophage infiltration as indicated by the number of adipocytes in AT (D) and <i>CD68</i> expression in the stroma-vascular fraction (E), adiponectin (F) and leptin (G) serum levels, as well as HOMA-IR as a measure insulin resistance (H). Pearson correlation coefficient R and <i>p</i>-value are given in each scatter plot. Significant <i>p</i>-values (<i>p</i><0.05) are indicated in bold.</p

<i>FTO</i> Obesity Risk Variants Are Linked to Adipocyte <i>IRX3</i> Expression and BMI of Children - Relevance of <i>FTO</i> Variants to Defend Body Weight in Lean Children?

<div><p>Background</p><p>Genome-wide association studies have identified variants within the <i>FTO</i> (fat mass and obesity associated) locus as the strongest predictors of obesity amongst all obesity-associated gene loci. Recent evidence suggests that variants in <i>FTO</i> directly affect human adipocyte function through targeting <i>IRX3</i> and <i>IRX5</i> and thermogenesis regulation.</p><p>Aim</p><p>We addressed the relevance of this proposed <i>FTO-IRX</i> pathway in adipose tissue (AT) of children.</p><p>Results</p><p>Expression of <i>IRX3</i> was higher in adipocytes compared to SVF. We found increased adipocyte-specific expression of <i>IRX3</i> and <i>IRX5</i> with the presence of the <i>FTO</i> risk haplotype in lean children, whereas it was unaffected by risk variants in obese peers. We further show that <i>IRX3</i> expression was elevated in isolated adipocytes and AT of lean compared to obese children, particularly in <i>UCP1</i>-negative adipocytes, and inversely correlated with BMI SDS. Independent of BMI, <i>IRX3</i> expression in adipocytes was significantly related to adipocyte hypertrophy, and subsequent associations with AT inflammation and HOMA-IR in the children.</p><p>Conclusion</p><p>One interpretation of our observation of <i>FTO</i> risk variants linked to <i>IRX3</i> expression and adipocyte size restricted to lean children, along with the decreased <i>IRX3</i> expression in obese compared to lean peers, may reflect a defense mechanism for protecting body-weight, which is pertinent for lean children.</p></div

<i>NAMPT</i> expression in response metabolic regulators.

<p>Preadipocytes (<b>A+C</b>) and adipocytes (day 10 of differentiation) (<b>B+D</b>) were stimulated with 100 nM insulin (Ins), 100 nM dexamethasone (Dex), 100 nM IGF-1and 100 nM isoproterenol (Iso) for 24 h and with increasing concentrations of glucose for 48 h as indicated. Expression in untreated cells (C) and at 17.5 mM glucose was set = 1. Data are shown for 3 independent cell experiments. Statistical significance was assessed by student's t-test.</p

<i>FTO</i> expression in response to metabolic regulators.

<p>Preadipocytes (<b>A+C</b>) and adipocytes (day 10 of differentiation) (<b>B+D</b>) were stimulated with 100 nM insulin (Ins), 100 nM dexamethasone (Dex), 100 nM IGF-1 and 100 nM isoproterenol (Iso) for 24 h and with increasing concentrations of glucose for 48 h as indicated. Expression in untreated cells (C) and at 17.5 mM glucose was set = 1. Data are shown for 3 independent cell experiments. Statistical significance was assessed by student's t-test.</p

Sequences of primer and probes.

<p>Sequences of primer and probes.</p

<i>FTO</i> and <i>RBL2</i> expression during adipogenesis.

<p><i>FTO</i> and <i>RBL2</i> expression was not modulated during <i>in vitro</i> differentiation of SGBS (<b>A</b>) and primary subcutaneous (<b>B</b>) preadipocytes to mature adipocytes (expression in preadipocytes at day 0 was set = 1). An expected increase in mRNA expression of <i>PPARγ</i> confirmed efficient adipogenesis. Data are shown for at least 3 independent cell experiments. Statistical significance was assessed by ANOVA with repeated measurements and Dunnett's post test. Data are mean±SEM.</p

Positive correlation between NAMPT serum levels and inflammatory markers.

<p>Correlation between log NAMPT serum concentration and log C-reactive protein (A), log ESR (1 hour) (B), log leucocyte count(C) and log neutrophil granulocyte count (D).</p

NAMPT serum concentrations in distinct inflammatory conditions.

<p>Comparison of NAMPT concentrations between patient groups of distinct inflammatory conditions and controls (A). Patients with chronic inflammation were further stratified into patients with active disease vs. patients without symptoms (remission) (B). Boxes are interquartile range, whiskers are minimum to maximum. Statistical significance was assessed by ANOVA and Tukey HSD test in log transformed values.</p