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Weisnagel, John

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Weisnagel

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John

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Université Laval. Faculté de médecine

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ncf10120368

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  • PublicationRestreint
    Combined effects of PPARγ2 P12A and PPARα L162V polymorphisms on glucose and insulin homeostasis : the Québec Family Study
    (Springer-Verlag, 2003-11-20) Bouchard, Claude; Pérusse, Louis; Weisnagel, John; Bossé, Yohan; Vohl, Marie-Claude; Després, Jean-Pierre
    Peroxisome proliferator-activated receptors γ2 and α are nuclear factors known to be important regulators of lipid and glucose metabolism. Two polymorphisms, namely PPARγ2 P12A and PPARα L162V, were investigated for their individual and interaction effects on glucose and insulin homeostasis. Genotypes were determined in 663 nondiabetic adults participating in the Québec Family Study and who underwent an oral glucose tolerance test (OGTT). The insulin and C-peptide areas under the curve (AUC) following the OGTT were higher in subjects carrying the PPARα V162 allele compared to homozygous for the L162 allele. When subjects were grouped according to both polymorphisms, higher levels of insulin and C-peptide during the OGTT were observed for those carrying the PPARα V162 allele except when they carry at the same time the PPARγ2 A12 allele. Thus, the PPARγ2 A12 allele seems protective against the deleterious effect of the PPARα V162 allele. Furthermore, a significant gene-gene interaction was observed for the acute (0–30 min) (p<0.001) and the total (p=0.05) C-peptide AUC following the OGTT. These results provide evidence of a gene-gene interaction in the regulation of plasma glucose-insulin homeostasis, and emphasize that these interactions need to be taken into account when dissecting the genetic etiology of complex disorders.
  • PublicationAccès libre
    Transcriptomic profiles of skeletal muscle tissue following an euglycemic-hyperinsulinemic clamp in insulin-resistant obese subjects
    (Springer Link, 2012-05-08) Rudkowska, Iwona; Weisnagel, John; Vohl, Marie-Claude; Jacques, Hélène; Marette, André
    Insulin resistance in skeletal muscle is an early phenomenon in the pathogenesis of type 2 diabetes. Muscle is mainly responsible for insulin-stimulated glucose clearance from the bloodstream. Thus, regulation of gene expression in muscle tissue may be involved in the pathogenesis of insulin resistance. The objective was to investigate gene expression and metabolic pathways alterations in skeletal muscle tissue following an euglycemic-hyperinsulinemic clamp in obese insulin-resistant subjects. We carried out a transcriptome comparison of skeletal muscle tissue before and after a 3-h euglycemic-hyperinsulinemic clamp following 8-week supplementation with n-3 polyunsaturated fatty acid (PUFA) (1.8 g/day) with or without a supplement of fish gelatin (FG) (25 % of daily protein intake) in 16 obese insulin-resistant subjects. Results indicate that approximately 5 % (1932) of expressed transcripts were significantly changed after the clamp in both n-3 PUFA and n-3 PUFA + FG supplementation periods. Of these differentially expressed transcripts, 1394 genes associated with enzymes, transcription and translation regulators, transporters, G protein-coupled receptors, cytokines, and ligand-dependent nuclear receptors were modified. Metabolic pathways that were significantly modified included liver X receptor/retinoid X receptors (RXR) activation, vitamin D receptor/RXR activation, interleukin (IL)-8, acute phase response, IL10, triggering receptor expressed on myeloid cells 1, peroxisome proliferator-activated receptor, G-beta/gamma and hepatocyte growth factor and IL6 signaling. Taken together, results suggest that mainly inflammatory and transcription factors are modified following clamp in obese insulin-resistant subjects. Overall, understanding the changes in metabolic pathways due to insulin may be a potential target for the management of insulin resistance.
  • PublicationRestreint
    Interaction between HNF4A polymorphisms and physical activity in relation to type 2 diabetes-related traits : results from the Quebec Family Study
    (Elsevier, 2009-04-29) Ruchat, Stéphanie-May; Bouchard, Claude; Rankinen, Tuomo; Pérusse, Louis; Weisnagel, John; Vohl, Marie-Claude
    Aims : To test for associations between type 2 diabetes mellitus (T2DM)-related traits and polymorphisms (SNPs) in the hepatocyte nuclear factor 4-α gene (HNF4A) in the Quebec Family Study cohort, and determine whether these associations are modulated by physical activity (PA). Methods : Two HNF4A SNPs (rs1885088 G > A; rs745975 C > T), previously reported to be associated with T2DM, were studied in 528 non-diabetic subjects who underwent a 75 g oral glucose tolerance test (OGTT). Glucose, insulin and C-peptide plasma levels, measured in the fasting state and during the OGTT, were used in the analysis. The amount (hours per week) of PA was assessed by questionnaire. Results : The HNF4A rs1885088 SNP was not independently associated with T2DM-related traits, whereas the rs745975 was associated with fasting insulin, HOMA-IR and 2-h glucose levels (p < 0.05 for all). Genotype by PA interactions were found for glucose homeostasis (p < 0.0001) and insulin secretion (p ≤ 0.03). When subjects were stratified by PA level (according to the median value), we found that high level of PA (>2 h/week) was associated with smaller glucose area under the curve (AUC) and 2-h glucose levels in rs1885088 A/A homozygotes and with lower fasting C-peptide and insulin AUC in rs745975 T/T homozygotes. Conclusion : These results indicate that the associations of HNF4A rs1885088 with glucose tolerance and rs745975 with insulin secretion are modulated by PA. Our finding therefore suggests that the effect of HNF4A polymorphisms on the risk of T2DM is influenced by PA.
  • PublicationRestreint
    Association between insulin secretion, insulin sensitivity and type 2 diabetes susceptibility variants identified in genome-wide association studies
    (Springer, 2008-12-10) Ruchat, Stéphanie-May; Elks, Cathy E.; Bouchard, Claude; Loos, Ruth; Pérusse, Louis; Weisnagel, John; Vohl, Marie-Claude; Rankinen, Tuomo
    Several single nucleotide polymorphisms (SNPs) for type 2 diabetes mellitus (T2DM) risk have been identified by genome wide association studies (GWAS). The objective of the present study was to investigate the impact of these SNPs on T2DM intermediate phenotypes in order to clarify the physiological mechanisms through which they exert their effects on disease etiology. We analysed 23 SNPs in 9 T2DM genes (CDKAL1, CDKN2B, HHEX/IDE, IGF2BP2, KCNJ11, SLC30A8, TCF2, TCF7L2 and WFS1) in a maximum of 712 men and women from the Quebec Family Study. The participants underwent a 75 g oral glucose tolerance test (OGTT) and were measured for glucose, insulin and C-peptide levels. Indices of insulin sensitivity and insulin secretion were derived from fasting and OGTT measurements. We confirmed the significant associations of variants in CDKAL1, CDKN2B, HHEX/IDE, KCNJ11 and TCF7L2 with insulin secretion and also found associations of some of these variants with insulin sensitivity and glucose tolerance. IGF2BP2 and SLC30A8 SNPs were not associated with insulin secretion but were with insulin sensitivity and glucose tolerance (0.002 B P B 0.02). To examine the joint effects of these variants and their contribution to T2DM endophenotypes variance, stepwise regression models were used and the model R2 was computed. The variance in the phenotypes explained by combinations of variants ranged from 2.0 to 8.5%. Diabetes-associated variants in CDKAL1, CDKN2B, HHEX/IDE, IGF2BP2, KCNJ11, SLC30A8 and TCF7L2 are associated with physiological alterations leading to T2DM, such as glucose intolerance, impaired insulin secretion or insulin resistance, supporting their role in the disease aetiology. These variants were found to account for 2.0–8.5% of the variance of T2DM-related traits.
  • PublicationRestreint
    Evidence for interaction between PPARG Pro12Ala and PPARGC1A Gly482Ser polymorphisms in determining type 2 diabetes intermediate phenotypes in overweight subjects
    (Thieme, 2009-06-17) Ruchat, Stéphanie-May; Bouchard, Claude; Pérusse, Louis; Rankinen, Tuomo; Weisnagel, John; Vohl, Marie-Claude
    Background: The peroxisome proliferator-activated receptor-γ (PPARG) Pro12Ala and the PPARG co-activator-1α (PPARGC1A) Gly482Ser polymorphisms (SNPs) have been associated with type 2 diabetes mellitus (T2DM) risk. We hypothesized that independent and interactive effects of the PPARG Pro12Ala and PPARGC1A Gly482Ser polymorphisms influence T2DM intermediate phenotypes. Material and Methods: PPARG Pro12Ala and PPARGC1A Gly482Ser SNPs were studied in 680 non diabetic subjects who underwent a 75 g oral glucose tolerant test (OGTT). Glucose and insulin plasma levels in the fasting state and derived from the OGTT were included in the present study. Results: We found significant independent effects of the PPARG and PPARGC1A variants on fasting insulin levels (p=0.02 for both), HOMA-IR (p=0.03 and p=0.02, respectively), insulin area under the curve (AUC) (p=0.007 and p=0.006, respectively) and 2-h glucose levels (p=0.02 for PPARGC1A). Furthermore, significant gene-gene interactions were found for fasting insulin, HOMA-IR and insulin AUC (p=0.03 for all). Carriers of the PPARGC1A Gly allele who were also PPARG Ala-carriers had higher fasting insulin levels (p=0.02), HOMA-IR (p=0.01) and insulin AUC (p=0.01) compared to the Ser/Ser-Ala+genotype combination, whereas no differences between the PPARGC1A genotypes among the PPARG Pro/Pro carriers were observed. Conclusion: Together, these results showed that PPARG Pro12Ala and PPARGC1A Gly482Ser variants are associated, alone and in interaction, with insulin and glucose homeostasis and suggest that gene-gene interactions should be taken into account in candidate gene studies of T2DM to identify subjects with markedly different risks of developing the disease.
  • PublicationRestreint
    Association between micro-opioid receptor-1 102T>C polymorphism and intermediate type 2 diabetes phenotypes : results from the Quebec Family Study (QFS)
    (Australian Society for Medical Research, 2008-08-01) Ruchat, Stéphanie-May; Girard, Martine; Bouchard, Claude; Pérusse, Louis; Weisnagel, John; Vohl, Marie-Claude
    It has been suggested recently that molecules expressed both in the pancreas and hypothalamus, such as mu-opioid receptor 1 (OPRM1), could form an integrated brain-liver system, which may sense glucose levels and therefore contribute to the development of type 2 diabetes mellitus (T2DM). In the present study, we tested associations between OPRM1 gene polymorphisms (rs1799971, 102T/C and rs0648007G/A) and indices of glucose tolerance, insulin sensitivity (IS) and insulin secretion derived from plasma measures obtained in a fasting state and following a 75 g oral glucose tolerance test (OGTT) in 749 subjects from the Quebec Family Study (QFS). Polymorphisms were tested for association with glucose tolerance (normal vs IFG and T2DM combined) by calculating a chi(2) statistic and corresponding P values, whereas associations with quantitative measures of glucose tolerance, IS and insulin secretion were tested using mixed linear models implemented in the MIXED procedure of sas (SAS Institute, Cary, NC, USA). Associations were found between 102T/C OPRM1 and indices of glucose tolerance and IS. Compared with T/T homozygotes, carriers of the OPRM1 C-102 variant exhibited a better glucose tolerance with a lower (P = 0.006) glucose area under the curve (AUC) following the OGTT and a better IS with a higher (P = 0.03) value of the Cederholm index, a numerical index of the curve relating glucose uptake to the log(10) plasma insulin levels during the OGTT. The results of the present study reveal that the 102T/C OPRM1 gene polymorphism is associated with a better glucose tolerance and improved IS, both of which suggest a potential protective effect of this variant on T2DM risk.