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Personne :
Guénard, Frédéric

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Guénard

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Frédéric

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Université Laval. Institut sur la nutrition et les aliments fonctionnels

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ncf11859489

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Voici les éléments 1 - 6 sur 6
  • PublicationAccès libre
    Genetic regulation of differentially methylated genes in visceral adipose tissue of severely obese men discordant for the metabolic syndrome
    (Elsevier, 2017-02-01) Guénard, Frédéric; Biron, Simon; Biertho, Laurent; Pérusse, Louis; Lescelleur, Odette; Vohl, Marie-Claude; Marceau, Simon (***WMS); Deshaies, Yves; Tchernof, André
    A genetic influence on methylation levels has been reported and methylation quantitative trait loci (meQTL) have been identified in various tissues. The contribution of genetic and epigenetic factors in the development of the metabolic syndrome (MetS) has also been noted. To pinpoint candidate genes for testing the association of SNPs with MetS and its components, we aimed to evaluate the contribution of genetic variations to differentially methylated CpG sites in severely obese men discordant for MetS. A genome-wide differential methylation analysis was conducted in visceral adipose tissue (VAT) of 31 severely obese men discordant for MetS (16 with and 15 without MetS) and identified ∼17,800 variable CpG sites. The genome-wide association study conducted to identify the SNPs (meQTL) associated with methylation levels at variable CpG sites revealed 2292 significant associations (P < 2.22 × 10−11) involving 2182 unique meQTLs regulating the methylation levels of 174 variable CpG sites. Two meQTLs disrupting CpG sites located within the collagen-encoding COL11A2 gene were tested for associations with MetS and its components in a cohort of 3021 obese individuals. Rare alleles of these meQTLs showed association with plasma fasting glucose levels. Further analysis conducted on these meQTL suggested a biological impact mediated through the disruption of transcription factor (TF)–binding sites based on the prediction of TF-binding affinities. The current study identified meQTL in the VAT of severely obese men and revealed associations of two COL11A2 meQTL with fasting glucose levels.
  • PublicationAccès libre
    Methylation and expression of immune and inflammatory genes in the offspring of bariatric bypass surgery patients.
    (Hindawi, 2013-06-11) Guénard, Frédéric; Marceau, Picard; Cianflone, Katherine M.; Vohl, Marie-Claude; Kral, John G.; Deshaies, Yves; Tchernof, André
    Background. Maternal obesity, excess weight gain and overnutrition during pregnancy increase risks of obesity, type 2 diabetes mellitus, and cardiovascular disease in the offspring. Maternal biliopancreatic diversion is an effective treatment for severe obesity and is beneficial for offspring born after maternal surgery (AMS). These offspring exhibit lower severe obesity prevalence and improved cardiometabolic risk factors including inflammatory marker compared to siblings born before maternal surgery (BMS). Objective. To assess relationships between maternal bariatric surgery and the methylation/expression of genes involved in the immune and inflammatory pathways. Methods. A differential gene methylation analysis was conducted in a sibling cohort of 25 BMS and 25 AMS offspring from 20 mothers. Following differential gene expression analysis (23 BMS and 23 AMS), pathway analysis was conducted. Correlations between gene methylation/expression and circulating inflammatory markers were computed. Results. Five immune and inflammatory pathways with significant overrepresentation of both differential gene methylation and expression were identified. In the IL-8 pathway, gene methylation correlated with both gene expression and plasma C-reactive protein levels. Conclusion. These results suggest that improvements in cardiometabolic risk markers in AMS compared to BMS offspring may be mediated through differential methylation of genes involved in immune and inflammatory pathways.
  • PublicationAccès libre
    Dissecting features of epigenetic variants underlying cardiometabolic risk using full-resolution epigenome profiling in regulatory elements.
    (Nature Publishing Group, 2019-03-14) Allum, Fiona; Guénard, Frédéric; Hedman, Åsa K.; Vohl, Marie-Claude; Shao, Xiaojian; Tchernof, André; Cheung, Warren A.; Vijay, Jinchu; Kwan, Tony; Simon, Marie-Michelle; Ge, Bing; Moura, Cristiano; Boulier, Elodie; Rönnblom, Lars; Bernatsky, Sasha; Lathrop, Mark; McCarthy, Mark I.; Deloukas, Panos; Pastinen, Tomi; Grundberg, Elin
    Sparse profiling of CpG methylation in blood by microarrays has identified epigenetic links to common diseases. Here we apply methylC-capture sequencing (MCC-Seq) in a clinical population of ~200 adipose tissue and matched blood samples (Ntotal~400), providing high-resolution methylation profiling (>1.3 M CpGs) at regulatory elements. We link methylation to cardiometabolic risk through associations to circulating plasma lipid levels and identify lipid-associated CpGs with unique localization patterns in regulatory elements. We show distinct features of tissue-specific versus tissue-independent lipid-linked regulatory regions by contrasting with parallel assessments in ~800 independent adipose tissue and blood samples from the general population. We follow-up on adipose-specific regulatory regions under (1) genetic and (2) epigenetic (environmental) regulation via integrational studies. Overall, the comprehensive sequencing of regulatory element methylomes reveals a rich landscape of functional variants linked genetically as well as epigenetically to plasma lipid traits.
  • PublicationAccès libre
    Bariatric surgery induces hypomethylation of genes related to type 2 diabetes and insulin resistance
    (MedCrave Group, 2017-04-21) Guénard, Frédéric; Toro Martin, Juan de; Marceau, Picard; Deshaies, Yves; Vohl, Marie-Claude; Tchernof, André
    Biliopancreatic diversion with duodenal switch (BPD-DS) is a surgical intervention known to induce substantial weight loss and significant long-lasting metabolic improvements including a decrease in insulin resistance (IR) and resolution of type 2diabetes(T2D). The specific mechanisms by which metabolic improvements occur after BPD-DS are still not fully elucidated and the impact of BPD-DS on gene methylation profiles has not been studied. To gain understanding of epigenetic factors that may predispose to metabolic improvements after weight loss surgery, we characterized the methylation signature of genes associated to T2D and IR after BPD-DS. Most of the genes involved in T2D and IR pathways exhibited significant differences in methylation levels after BPD-DS compared to a pre-surgery control group. The majority of these loci were significantly hypomethylated, suggesting an effect of bariatric surgery on the epigenetic signature of genes encoding proteins involved in glucose homeostasis.
  • PublicationAccès libre
    Differential methylation of inflammatory and insulinotropic genes after metabolic surgery in women
    (iMed Pub LLC, 2015-10-03) Guénard, Frédéric; Marceau, Picard; Cianflone, Katherine M.; Deshaies, Yves; Vohl, Marie-Claude; Tchernof, André; Kral, John G.
    Context: Biliopancreatic diversion with duodenal switch (BPD-DS), a metabolic bariatric operation, induces durable loss of excess weight and reduced cardiometabolic risk. Altered epigenetic marks are mechanistically associated with environment-driven phenotypic variations. Objective: The current study aimed to compare gene methylation levels before and after BPD-DS to identify epigenetic marks potentially linked to metabolic improvements induced by BPD-DS. Design and patients: Metabolic risk factors and gene methylation levels of 20 women studied mean 12 years (range 4-22) after BPD-DS were compared to those of 20 severely obese surgical candidates as controls, matched for pre-surgical age, body mass index and dyslipidemia and hypertension prevalences. Whole-genome blood DNA methylation analysis enabled between-group differential methylation analyses. We calculated correlations between methylation levels of the most differentially methylated CpG sites and plasma glucose and insulin levels and HOMA-IR. Results: Differential methylation analysis identified 15,343 genes demonstrating at least one differentially methylated CpG site (p<1.43x10-7). Diabetic and inflammation/immune functions were among the most overrepresented from the 200 genes exhibiting the largest group differences in methylation levels. CpG sites methylation levels of genes related to insulin action correlated significantly with fasting insulin levels and homeostatic model of insulin resistance (p≤0.002 for all). Conclusion: These findings suggest that differential methylation levels in obese controls versus treated women may partially explain the durable metabolic improvements after BPD-DS.
  • PublicationRestreint
    Differential methylation in visceral adipose tissue of obese men discordant for metabolic disturbances
    (American Physiological Society, 2014-03-15) Guénard, Frédéric; Biron, Simon; Biertho, Laurent; Pérusse, Louis; Lescelleur, Odette; Vohl, Marie-Claude; Deshaies, Yves; Marceau, Simon; Tchernof, André
    Obesity is associated with an increased risk of Type 2 diabetes and cardiovascular diseases (CVD). The severely obese population is heterogeneous regarding CVD risk profile. Our objective was to identify metabolic pathways potentially associated with development of metabolic syndrome (MetS) through an analysis of overrepresented pathways from differentially methylated genes between severely obese men with (MetS+) and without (MetS-) the MetS. Genome-wide quantitative DNA methylation analysis in VAT of severely obese men was carried out using the Infinium HumanMethylation450 BeadChip. Differences in methylation levels between MetS+ (n = 7) and MetS- (n = 7) groups were tested. Overrepresented pathways from the list of differentially methylated genes were identified and visualized with the Ingenuity Pathway Analysis system. Differential methylation analysis between MetS+ and MetS- groups identified 8,578 methylation probes (3,258 annotated genes) with significant differences in methylation levels (false discovery rate-corrected DiffScore ≥ |13| ∼ P ≤ 0.05). Pathway analysis from differentially methylated genes identified 41 overrepresented (P ≤ 0.05) pathways. The most overrepresented pathways were related to structural components of the cell membrane, inflammation and immunity and cell cycle regulation. This study provides potential targets associated with adipose tissue dysfunction and development of the MetS.