There are major variations in the susceptibility to weight gain among individuals undersimilar external influences (decreased physical activity and excessive calorie intake),depending on the genetic background. In the present study, we performed a microarrayanalysis and RT-PCR validations in order to find out differential gene expression insubcutaneous abdominal adipose tissue from two groups of subjects that despite livingin similar environmental conditions such as a habitual high fat dietary intake (energy asfat >40%) and similar moderate physical activity, some of them were successfully“resistant” (lean) to weight gain, while others were “susceptible” to fat deposition(obese). The classification of up- and down- regulated genes into different categoriestogether with the analysis of the altered biochemical pathways, revealed a coordinateddownregulation of catabolic pathways operating in the mitochondria: fatty acidoxidation (P=0.008), TCA cycle (P=0.001) and electron transport chain (P=0.012). Atthe same time, glucose metabolism (P=0.010) and fatty acid biosynthesis (P=0.011)pathways were also downregulated in obese compared to lean subjects. In conclusion,our data showed an orchestrated downregulation of nuclear-encoded mitochondrial geneexpression. These genes are involved in cellular respiration and oxidative metabolismpathways, and could play a role in the susceptibility to weight gain in some individuals.
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