The current work identified three CpG sites located in coding regions of three miRNAs (miR-1203, miR-412 and miR-216A) that were differentially methylated between obese and non-obese children, suggesting a role of miRNA epigenetic regulation in childhood obesity.

The main aim of this investigation was to study the regulatory roles of let-7b and miR-155-3p on the expression of inflammation-associated genes in monocytes, macrophages, and lipopolysaccharide (LPS)-activated macrophages (AcM). A second goal was to analyze the potential modulatory roles of different fatty acids, including oleic, palmitic, eicosapentaenoic (EPA), and docosahexaenoic (DHA), on the expression of these miRNAs in the three cell types. This hypothesis was tested in human acute monocytic leukemia cells (THP-1), which were differentiated into macrophages with 2-O-tetradecanoylphorbol-13-acetate (TPA) and further activated with LPS for 24 h. Monocytes, macrophages, and AcM were transfected with a negative control, or mimics for miR-155-3p and miR-let-7b-5p. The expression of both miRNAs and some proinflammatory genes was analyzed by qRT-PCR. Interestingly, let-7b mimic reduced the expression of IL6 and TNF in monocytes, and SERPINE1 expression in LPS-activated macrophages. However, IL6, TNF, and SERPINE1 were upregulated in macrophages by let-7b mimic. IL6 expression was higher in the three types of cells after transfecting with miR-155-3p mimic. Similarly, expression of SERPINE1 was increased by miR-155-3p mimic in monocytes and macrophages. However, TLR4 was downregulated by miR-155-3p in monocytes and macrophages. Regarding the effects of the different fatty acids, oleic acid increased the expression of let-7b in macrophages and AcM and also increased the expression of miR-155 in monocytes when compared with DHA but not when compared with non-treated cells. Overall, these results suggest anti- and proinflammatory roles of let-7b and miR-155-3p in THP-1 cells, respectively, although these outcomes are strongly dependent on the cell type. Noteworthy, oleic acid might exert beneficial anti-inflammatory effects in immune cells (i.e., non-activated and LPS-activated macrophages) by upregulating the expression of let-7b.

The epigenetic mechanisms of action of resveratrol as an anti-obesity molecule have not been fully addressed so far. The aim of the present study was to assess changes produced by resveratrol in the microRNA (miRNA) profile in white adipose tissue (WAT) and to relate these changes to those induced in the expression of genes involved in triacylglycerol metabolism. Male Wistar rats were fed (6 weeks) an obesogenic diet: a control group and a group treated with resveratrol (30 mg kg(-1) d(-1)). A miRNA microarray was carried out in perirenal adipose tissue. The overexpression of miR-539-5p and miR-1224-5p was performed in 3T3-L1 cells. Protein expression was analysed by western-blot and gene expression by qRT-PCR. Associations between variables were assessed by Pearson's correlations. The microarray showed that 3 miRNAs were decreased and 13 were increased after resveratrol treatment. Among those miRNAs increased, miR-129, miR-328-5p and miR-539-5p showed predicted target genes relevant for triacylglycerol metabolism in WAT (pparγ: peroxisome proliferator-activated receptor gamma, hsl: hormone sensitive lipase and sp1: SP1 transcription factor) in the miRWalk database. Moreover, the literature shows that miR-1224, another miRNA up-regulated by resveratrol, can also regulate sp1. Among the three targets, only SP1 showed a reduction in protein expression. Correlation and overexpression studies revealed that the decrease in SP1 protein expression was only associated with the increase of miR-539-5p. In addition, significant reductions in SREBP1 protein expression and fasn gene expression were found in resveratrol-treated rats. In conclusion, the up-regulation of miR-539-5p is involved in the inhibition of de novo lipogenesis induced by resveratrol in WAT.

www.clinicaltrials.gov : NCT01087086.

BackgroundNon-coding RNAs (i.e., miRNAs) play a role in the development of obesity and related comorbidities and the regulation of body weight.ObjectiveTo identify candidate miRNA biomarkers throughout omics approaches in order to predict the response to specific weight-loss dietary treatments.DesignGenomic DNA and cDNA isolated from white blood cells of a subset from the RESMENA nutritional intervention study (Low-responders (LR) vs High-responders (HR)) was hybridized in Infinium Human Methylation450 BeadChip and in Illumina Human HT-12 v4 gene expression BeadChips arrays respectively. A bioinformatic prediction of putative target sites of selected miRNAs was performed by applying miRBase algorithms. HEK-293T cells were co-transfected with expression vectors containing the 3’-UTR of candidate genes to validate the binding of miRNAs to its target sites.Results134 miRNAs were differentially methylated between HR and LR in the methylation array, whereas 44 miRNAs were differentially expressed between both groups in the expression array. Specifically, miR-1237, miR-1976, miR-642, miR-636, miR-612 and miR-193B were simultaneously hypomethylated and overexpressed in HR. miR-612 and miR-1976 showed greatest differences in methylation and expression levels, respectively. The bioinformatic prediction revealed that TP53 was a putative target gene of miR-612 and CD40 of miR-1976. Moreover, TP53 was downregulated in the expression array when comparing HR vs LR expression levels adjusted by sex, diet, age and baseline weight, and CD40 showed a statistical trend. Furthermore, gene expression levels of TP53 and CD40 in white blood cells, when measured by qPCR, were also downregulated in HR. Finally, miR-612 and miR-1976 potently repressed TP53 and CD40 respectively by targeting its 3’-UTR regions.ConclusionmiR-612 and miR-1976 levels could be prospective biomarkers of response to specific weight-loss diets and might regulate the gene expression of TP53 and CD40.