Genome-wide expression in visceral adipose tissue from obese prepubertal children

Abstract

Characterization of the genes expressed in adipose tissue (AT) is key to understanding the pathogenesis of obesity and to developing treatments for this condition. Our objective was to compare the gene expression in visceral AT (VAT) between obese and normal-weight prepubertal children. A total of fifteen obese and sixteen normal-weight children undergoing abdominal elective surgery were selected. RNA was extracted from VAT biopsies. Microarray experiments were independently performed for each sample (six obese and five normal-weight samples). Validation by quantitative PCR (qPCR) was performed on an additional 10 obese and 10 normal-weight VAT samples. Of 1276 differentially expressed genes (p < 0.05), 245 were more than two-fold higher in obese children than in normal-weight children. As validated by qPCR, expression was upregulated in genes involved in lipid and amino acid metabolism (CES1, NPRR3 and BHMT2), oxidative stress and extracellular matrix regulation (TNMD and NQO1), adipogenesis (CRYAB and AFF1) and inflammation (ANXA1); by contrast, only CALCRL gene expression was confirmed to be downregulated. In conclusion, this study in prepubertal children demonstrates the up- and down-regulation of genes that encode molecules that were previously proposed to influence the pathogenesis of adulthood obesity, as well as previously unreported dysregulated genes that may be candidate genes in the aetiology of obesity.

Figure 1

Venn diagram of the expressed sequences in the visceral adipose tissue of obese and normal-weight prepubertal children. After filtering the data with the Affymetrix Detection Algorithm, a total of 12,057 sequences were found to be expressed in adipose tissue. Each condition is represented by a circle in the Venn diagram. The numbers in the region of the overlapping circles indicate the genes that are expressed in both conditions.

Figure 2

Microarray analysis of the transcripts expressed in the visceral adipose tissue from obese vs. normal-weight (control) prepubertal children. RNA from each patient was subjected to chip analysis using Affymetrix Human Genome U133Plus 2.0 GeneChips. The normal-weight group consists of six individuals (numbers 1–6), and the obese group consists of five patients (numbers 7–11). Bidimensional cluster analysis was performed using a Pearson correlation. The parametric test ANOVA was used to uncover the 1588 genes that were differentially expressed.