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Gaudreault, Nathalie

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Université Laval. Département de physiologie
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  • Publication
    Altered DNA methylation of long noncoding RNA H19 in calcific aortic valve disease promotes mineralization by silencing NOTCH1
    (American Heart Association, 2016-12-06) Gaudreault, Nathalie; Bouchareb, Rihab; Guay, Simon-Pierre; Amellah, Soumiya; Mkannez, Guada; Tremblay-Marchand, Joël; Boulanger, Marie-Chloé; Guauque-Olarte, Sandra; Bossé, Yohan; Pibarot, Philippe; Hadji, Fayez; Bouchard, Luigi; Nsaibia, Mohamed Jalloul; Mathieu, Patrick
    Background: Calcific aortic valve disease is characterized by an abnormal mineralization of the aortic valve. Osteogenic activity in the aortic valve is under the control of NOTCH1, which regulates the expression of key pro-osteogenic genes such as RUNX2 and BMP2. Long noncoding RNAs (lncRNAs) may reprogram cells by altering the gene expression pattern. Methods: Multidimensional genomic profiling was performed in human aortic valves to document the expression of lncRNAs and the DNA methylation pattern in calcific aortic valve disease. In-depth functional assays were carried out to document the impact of lncRNA on the mineralization of the aortic valve. Results: We documented that lncRNA H19 (H19) was increased in calcific aortic valve disease. Hypomethylation of the promoter region was observed in mineralized aortic valves and was inversely associated with H19 expression. Knockdown and overexpression experiments showed that H19 induces a strong osteogenic phenotype by altering the NOTCH1 pathway. Gene promoter analyses showed that H19 silenced NOTCH1 by preventing the recruitment of p53 to its promoter. A knockdown of H19 in valve interstitial cells (VICs) increased the expression of NOTCH1 and decreased the level of RUNX2 and BMP2, 2 downstream targets repressed by NOTCH1. In rescue experiments, the transfection of a vector encoding for the active Notch intracellular domain prevented H19-induced mineralization of valve interstitial cells. Conclusions: These findings indicate that a dysregulation of DNA methylation in the promoter of H19 during calcific aortic valve disease is associated with a higher expression of this lncRNA, which promotes an osteogenic program by interfering with the expression of NOTCH1.
  • Publication
    Accès libre
    Deleterious variants in DCHS1 are prevalent in sporadic cases of mitral valve prolapse
    (John Wiley & Sons, 2017-12-10) Gaudreault, Nathalie; Bérubé, Jean-Christophe; Bélanger, Paméla; Capoulade, Romain; Clemenceau, Alisson; Bossé, Yohan; Toubal, Oumhani; Lamontagne, Maxime; Pibarot, Philippe; Clavel, Marie-Annick; Mathieu, Patrick
    Background A recent study identified DCHS1 as a causal gene for mitral valve prolapse. The goal of this study is to investigate the presence and frequency of known and novel variants in this gene in 100 asymptomatic patients with moderate to severe organic mitral regurgitation. Methods DNA sequencing assays were developed for two previously identified functional missense variants, namely p.R2330C and p.R2513H, and all 21 exons of DCHS1. Pathogenicity of variants was evaluated in silico. Results p.R2330C and p.R2513H were not identified in this cohort. Sequencing all coding regions revealed eight missense variants including six considered deleterious. This includes one novel variant (p.A2464P) and two rare variants (p.R2770Q and p.R2462Q). These variants are predicted to be deleterious with combined annotation-dependent depletion (CADD) scores greater than 25, which are in the same range as p.R2330C (CADD = 28.0) and p.R2513H (CADD = 24.3). More globally, 24 of 100 cases were carriers of at least one in silico-predicted deleterious missense variant in DCHS1, suggesting that this single gene may account for a substantial portion of cases. Conclusion This study reveals an important contribution of germline variants in DCHS1 in unrelated patients with mitral valve prolapse and supports genetic testing of this gene to screen individuals at risk.
  • Publication
    RNA expression profile of calcified bicuspid, tricuspid, and normal human aortic valves by RNA sequencing
    (American Physiological Society, 2016-10-01) Gaudreault, Nathalie; Tremblay-Marchand, Joël; Kalavrouziotis, Dimitri; Droit, Arnaud; Guauque-Olarte, Sandra; Bossé, Yohan; Seidman, Jonathan G.; Pibarot, Philippe; Body, Simon C.; Dagenais, François.; Mathieu, Patrick
    The molecular mechanisms leading to premature development of aortic valve stenosis (AS) in individuals with a bicuspid aortic valve are unknown. The objective of this study was to identify genes differentially expressed between calcified bicuspid aortic valves (BAVc) and tricuspid valves with (TAVc) and without (TAVn) AS using RNA sequencing (RNA-Seq). We collected 10 human BAVc and nine TAVc from men who underwent primary aortic valve replacement. Eight TAVn were obtained from men who underwent heart transplantation. mRNA levels were measured by RNA-Seq and compared between valve groups. Two genes were upregulated, and none were downregulated in BAVc compared with TAVc, suggesting a similar gene expression response to AS in individuals with bicuspid and tricuspid valves. There were 462 genes upregulated and 282 downregulated in BAVc compared with TAVn. In TAVc compared with TAVn, 329 genes were up- and 170 were downregulated. A total of 273 upregulated and 147 downregulated genes were concordantly altered between BAVc vs. TAVn and TAVc vs. TAVn, which represent 56 and 84% of significant genes in the first and second comparisons, respectively. This indicates that extra genes and pathways were altered in BAVc. Shared pathways between calcified (BAVc and TAVc) and normal (TAVn) aortic valves were also more extensively altered in BAVc. The top pathway enriched for genes differentially expressed in calcified compared with normal valves was fibrosis, which support the remodeling process as a therapeutic target. These findings are relevant to understand the molecular basis of AS in patients with bicuspid and tricuspid valves.
  • Publication
    Identification of gender-specific genetic variants in patients with bicuspid aortic valve
    (Elsevier, 2016-02-01) Gaudreault, Nathalie; Henry, Cindy; Sbarra, Laura; Dargis, Natasha; Bossé, Yohan; Lamontagne, Maxime; Pibarot, Philippe; Mathieu, Patrick
    Bicuspid aortic valve (BAV) is the most frequent congenital heart defect and has a male predominance of 3 to 1. A large proportion of patients develop valvular and aortic complications. Despite the high prevalence of BAV, its cause and genetic origins remain elusive. The goal of this study was to identify genetic variants associated with BAV. Nine genes previously associated with BAV (NOTCH1, AXIN1, EGFR, ENG, GATA5, NKX2-5, NOS3, PDIA2, and TGFBR2) were sequenced in 48 patients with BAV using the Ion Torrent Personal Genome Machine. Pathogenicity of genetic variants was evaluated with the Combined Annotation Dependent Depletion framework. A selection of 89 variants identified by sequencing or in previous BAV genetic studies was genotyped, and allele frequencies were compared in 323 patients with BAV confirmed at surgery and 584 controls. Analyses were also performed by gender. Nine novel and 19 potentially pathogenic variants were identified by next-generation sequencing and confirmed by Sanger sequencing, but they were not associated with BAV in the case-control population. A significant association was observed between an in silico-predicted benign EGFR intronic variant (rs17290301) and BAV. Analyses performed by gender revealed different variants associated with BAV in men (EGFR rs533525993 and TEX26 rs12857479) and women (NOTCH1 rs61751489, TGFBR2 rs1155705, and NKX2-5 rs2277923). In conclusion, these results constitute the first association between EGFR genetic variants and BAV in humans and support a possible role of gender-specific polymorphisms in the development of BAV.
  • Publication
    Calcium signaling pathway genes RUNX2 and CACNA1C are associated with calcific aortic valve disease
    (American Heart Association, 2015-11-09) Gaudreault, Nathalie; Messika-Zeitoun, David; Arsenault, Benoit; Tremblay-Marchand, Joël; Droit, Arnaud; Lavoie-Charland, Émilie; Guauque-Olarte, Sandra; Bossé, Yohan; Lamontagne, Maxime; Dubé, Marie-Pierre; Pibarot, Philippe; Tardif, Jean-Claude; Mathieu, Patrick; Body, Simon C.; Seidman, Jonathan G.; Boileau, Catherine
    BACKGROUND—: Calcific aortic valve stenosis (AS) is a life-threatening disease with no medical therapy. The genetic architecture of AS remains elusive. This study combines genome-wide association studies, gene expression, and expression quantitative trait loci mapping in human valve tissues to identify susceptibility genes of AS. METHODS AND RESULTS—: A meta-analysis was performed combining the results of 2 genome-wide association studies in 474 and 486 cases from Quebec City (Canada) and Paris (France), respectively. Corresponding controls consisted of 2988 and 1864 individuals with European ancestry from the database of genotypes and phenotypes. mRNA expression levels were evaluated in 9 calcified and 8 normal aortic valves by RNA sequencing. The results were integrated with valve expression quantitative trait loci data obtained from 22 AS patients. Twenty-five single-nucleotide polymorphisms had P<5×10 in the genome-wide association studies meta-analysis. The calcium signaling pathway was the top gene set enriched for genes mapped to moderately AS-associated single-nucleotide polymorphisms. Genes in this pathway were found differentially expressed in valves with and without AS. Two single-nucleotide polymorphisms located in RUNX2 (runt-related transcription factor 2), encoding an osteogenic transcription factor, demonstrated some association with AS (genome-wide association studies P=5.33×10). The mRNA expression levels of RUNX2 were upregulated in calcified valves and associated with eQTL-SNPs. CACNA1C encoding a subunit of a voltage-dependent calcium channel was upregulated in calcified valves. The eQTL-SNP with the most significant association with AS located in CACNA1C was associated with higher expression of the gene. CONCLUSIONS—: This integrative genomic study confirmed the role of RUNX2 as a potential driver of AS and identified a new AS susceptibility gene, CACNA1C, belonging to the calcium signaling pathway.
  • Publication
    ATP acts as a survival signal and prevents the mineralization of aortic valve
    (Academic Press Inc, Ltd., 2012-05-01) Gaudreault, Nathalie; Fournier, Dominique; Audet, Audrey; Côté, Nancy; Bouchard-Cannon, Pascale; Guauque-Olarte, Sandra; Bossé, Yohan; El Husseini, Diala; Ducharme, Valérie; Pépin, Andrée; McKee, Marc D.; Simard, Chantale; Pibarot, Philippe; Derbali, Habib; Després, Jean-Pierre; Mathieu, Patrick
    Calcific aortic valve disease (CAVD) is a disorder related to progressive mineralization of valvular tissue that is a leading cause of heart disease. Thus far, there is no medical treatment to prevent the mineralization of aortic valves. It is generally thought that pathologic mineralization is linked to apoptosis of vascular cells. However, the role of apoptosis during mineralization as well as the survival signals for valvular interstitial cells (VICs), the main cellular component of aortic valves, remains to be identified. Here, through several lines of evidence, we show that bioavailability of extracellular ATP is a signal which determines survival or apoptosis of VICs and, in doing so, plays a major role in the development of CAVD. Specifically, in CAVD and in VIC cultures undergoing mineralization, we found a high level of the ectonucleotidase ENPP1. In addition, a genetic polymorphism in the intron 9 of the ENPP1 gene was associated with CAVD in a case-control cohort as well as with mRNA expression levels of ENPP1 in aortic valves. A high level of ENPP1 in CAVD promoted apoptosis-mediated mineralization of VICs by depleting the extracellular pool of ATP. We then documented that release of ATP by VICs promoted cell survival via the P2Y(2) receptor and the PI3K/Akt signaling pathway. Hence, our results show that level of ENPP1 modulates extracellular concentration of ATP, which is an important survival signal for VICs. These findings may help to develop novel pharmacological treatment for CAVD.
  • Publication
    Accès libre
    NOTCH1 genetic variants in patients with tricuspid calcific aortic valve stenosis
    (Middlesex, 2013-03-01) Gaudreault, Nathalie; Guauque-Olarte, Sandra; Bossé, Yohan; Ducharme, Valérie; Pibarot, Philippe; Mathieu, Patrick
    BACKGROUND AND AIM OF THE STUDY: Calcific aortic valve stenosis (AS) affects 2-5% of the population aged > 65 years. Functional DNA variants at the NOTCH1 locus result in bicuspid aortic valve (BAV) and severe valve calcification. The contribution of these variants to AS in the population with tricuspid aortic valve (TAV) remains to be determined. METHODS: Fourteen genetic variants surrounding the NOTCH1 gene were genotyped, including rare mutations previously reported, and common polymorphisms. The study involved 457 French Canadian patients with severe tricuspid AS. Genotyping was carried out using the Illumina BeadXpress platform. Allele frequencies of common single nucleotide polymorphisms (SNPs) for patients with AS were compared to a shared control group of European ancestry (n = 3,294). In total, 88 ancestry-informative markers were used to correct for population stratification. RESULTS: The mutation R1107X, previously associated with AS and BAV, was identified in a relatively young patient (aged 58 years). The mutations R1279H and V2285I were detected in 18 and 14 heterozygotes, respectively. A common polymorphism (rs13290979) located in intron 2 was significantly associated with AS (p = 0.003), which remained significant after correction for multiple testing. However, this association was no longer significant after accounting for population stratification (p = 0.088). CONCLUSION: In this study, rare functional variants were found in the NOTCH1 gene in a French Canadian population of patients with severe tricuspid AS. This also suggests, for the first time, the presence of a common polymorphism in this gene conferring susceptibility to AS.
  • Publication
    Replication of genetic association studies in aortic stenosis in adults
    (Elsevier, 2011-11-01) Gaudreault, Nathalie; Guauque-Olarte, Sandra; Bossé, Yohan; Ducharme, Valérie; Lamontagne, Maxime; Pibarot, Philippe; Mathieu, Patrick
    Only a handful of studies have attempted to unravel the genetic architecture of calcific aortic valve stenosis (AS). The goal of this study was to validate genes previously associated with AS. Seven genes were assessed: APOB, APOE, CTGF, IL10, PTH, TGFB1, and VDR. Each gene was tested for a comprehensive set of single-nucleotide polymorphisms (SNPs). SNPs were genotyped in 457 patients who underwent surgical aortic valve replacement, and allele frequencies were compared to 3,294 controls. A missense mutation in the APOB gene was significantly associated with AS (rs1042031, E4181K, p = 0.00001). A second SNP located 5.6 kilobases downstream of the APOB stop codon was also associated with the disease (rs6725189, p = 0.000013). Six SNPs surrounding the IL10 locus were strongly associated with AS (0.02 > p > 6.2 × 10¯¹¹). The most compelling association for IL10 was found with a promoter polymorphism (rs1800872) well known to regulate the production of the encoded anti-inflammatory cytokine. The frequency of the low-producing allele was greater in cases compared to controls (30% vs 20%, p = 6.2 × 10¯¹¹). SNPs in PTH, TGFB1, and VDR had nominal p values <0.05 but did not resist Bonferroni correction. In conclusion, this study suggests that subjects carrying specific polymorphisms in the IL10 and APOB genes are at higher risk for developing AS.
  • Publication
    Accès libre
    Genetic association analyses highlight IL6, ALPL, and NAV1 as three new susceptibility genes underlying calcific aortic valve stenosis
    (American Heart Association, 2019-10-15) Gaudreault, Nathalie; Dina, Christian; Thériault, Sébastien; Messika-Zeitoun, David; Arsenault, Benoit; Le Scouarnec, Solena; Capoulade, Romain; Boureau, Anne-Sophie; Bossé, Yohan; Rigade, Sidwell; Lamontagne, Maxime; Li, Zhonglin; Pibarot, Philippe; Simonet, Floriane; Clavel, Marie-Annick; Dagenais, François.; Mathieu, Patrick; Lecointe, Simon; Baron, Estelle; Bonnaud, Stéphanie; Karakachoff, Matilde; Charpentier, Eric; Fellah, Imen; Roussel, Jean-Christian; Verhoye, Jean Philippe; Baufreton, Christophe; Probst, Vincent; Roussel, Ronan; Redon, Richard; Le Tourneau, Thierry; Schott, Jean-Jacques
    Background: Calcific aortic valve stenosis (CAVS) is a frequent and life-threatening cardiovascular disease for which there is currently no medical treatment available. To date, only 2 genes, LPA and PALMD, have been identified as causal for CAVS. We aimed to identify additional susceptibility genes for CAVS. Methods: A GWAS (genome-wide association study) meta-analysis of 4 cohorts, totaling 5115 cases and 354 072 controls of European descent, was performed. A TWAS (transcriptome-wide association study) was completed to integrate transcriptomic data from 233 human aortic valves. A series of post-GWAS analyses were performed, including fine-mapping, colocalization, phenome-wide association studies, pathway, and tissue enrichment as well as genetic correlation with cardiovascular traits. Results: In the GWAS meta-analysis, 4 loci achieved genome-wide significance, including 2 new loci: IL6 (interleukin 6) on 7p15.3 and ALPL (alkaline phosphatase) on 1p36.12. A TWAS integrating gene expression from 233 human aortic valves identified NAV1 (neuron navigator 1) on 1q32.1 as a new candidate causal gene. The CAVS risk alleles were associated with higher mRNA expression of NAV1 in valve tissues. Fine-mapping identified rs1800795 as the most likely causal variant in the IL6 locus. The signal identified colocalizes with the expression of the IL6 RNA antisense in various tissues. Phenome-wide association analyses in the UK Biobank showed colocalized associations between the risk allele at the IL6 lead variant and higher eosinophil count, pulse pressure, systolic blood pressure, and carotid artery procedures, implicating modulation of the IL6 pathways. The risk allele at the NAV1 lead variant colocalized with higher pulse pressure and higher prevalence of carotid artery stenosis. Association results at the genome-wide scale indicated genetic correlation between CAVS, coronary artery disease, and cardiovascular risk factors. Conclusions: Our study implicates 3 new genetic loci in CAVS pathogenesis, which constitute novel targets for the development of therapeutic agents.
  • Publication
    Accès libre
    A transcriptome-wide association study identifies PALMD as a susceptibility gene for calcific aortic valve stenosis
    (Nature Publishing Group, 2018-03-07) Gaudreault, Nathalie; Thériault, Sébastien; Rosa, Mickael; Boulanger, Marie-Chloé; Capoulade, Romain; Messika-Zeitoun, David; Bossé, Yohan; Lamontagne, Maxime; Pibarot, Philippe; Clavel, Marie-Annick; Dagenais, François.; Mathieu, Patrick
    Calcific aortic valve stenosis (CAVS) is a common and life-threatening heart disease and the current treatment options cannot stop or delay its progression. A GWAS on 1009 cases and 1017 ethnically matched controls was combined with a large-scale eQTL mapping study of human aortic valve tissues (n = 233) to identify susceptibility genes for CAVS. Replication was performed in the UK Biobank, including 1391 cases and 352,195 controls. A tran- scriptome-wide association study (TWAS) reveals PALMD (palmdelphin) as significantly associated with CAVS. The CAVS risk alleles and increasing disease severity are both associated with decreased mRNA expression levels of PALMD in valve tissues. The top variant identified shows a similar effect and strong association with CAVS (P = 1.53 × 10−10) in UK Biobank. The identification of PALMD as a susceptibility gene for CAVS provides insights into the genetic nature of this disease, opens avenues to investigate its etiology and to develop much-needed therapeutic options.