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Personne :
Desjardins, Sylvie

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Desjardins

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Sylvie

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Université Laval. Département de médecine moléculaire

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ncf13710164

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Voici les éléments 1 - 4 sur 4
  • PublicationRestreint
    Factors affecting interindividual variability of hepatic UGT2B17 protein expression examined using a novel specific monoclonal antibody
    (American Society for Pharmacology and Experimental Therapeutics, etc., 2019-02-28) Lévesque, Éric; Rouleau, Michèle; Labriet, Adrien; Emond, Jean-Philippe; Hovington, Hélène; Périgny, Martine; Desjardins, Sylvie; Têtu, Bernard; Lacombe, Louis; Brisson, Hervé.; Guillemette, Chantal; Caron, Patrick; Fallon, John K.; Villeneuve, Lyne; Klein, Kathrin; Simonyan, David; Smith, Philip; Zanger, Ulrich M.
    The accurate quantification of the metabolic enzyme UGT2B17 has been hampered by the high sequence identity with other UGT2B enzymes (as high as 94%) and by the lack of a specific antibody. Knowing the significance of the UGT2B17 pathway in drug and hormone metabolism and cancer, we developed a specific monoclonal antibody (EL-2B17mAb), initially validated by the lack of detection in liver microsomes of an individual carrying no UGT2B17 gene copy and in supersomes expressing UGT2B enzymes. Immunohistochemical detection in livers reveals a strong labeling of bile ducts and variable labeling of hepatocytes. Expression levels assessed by immunoblotting were highly correlated to mass spectrometry-based quantification (r = 0.93) and three major expression patterns (absent, low or high) were evidenced. Livers with very low expression were carriers of the functional rs59678213 G variant, which is located in the binding site for the transcription factor Forkhead Box A1 (FOXA1) of the UGT2B17 promoter. The highest expression was observed for individuals carrying at least one rs59678213 A allele. A multiple regression analysis indicated that the number of gene copies explained only 8% of UGT2B17 protein expression, 49% when adding rs59678213 and reached 54% when including sex. The novel EL-2B17mAb antibody allowed specific UGT2B17 quantification and exposed different patterns of hepatic expression. It further suggests that FOXA1 is a key driver of UGT2B17 expression in the liver. The availability of this molecular tool will help characterize UGT2B17 level in various disease states and establish more precisely the UGT2B17 enzyme contribution to drug and hormone metabolism
  • PublicationAccès libre
    Analyse de gènes candidats au cancer du sein impliqués dans les interactions avec BRCA1 et BRCA2
    (2010) Desjardins, Sylvie; Durocher, Francine
    La susceptibilité d'un individu à développer un cancer du sein est le résultat d'une interaction complexe de facteurs reliés au style de vie, à l'histoire reproductive et aux déterminants génétiques propres à chaque individu. Jusqu'à présent, un nombre limité de gènes ont été impliqués dans une telle susceptibilité. Il est présentement estimé que des mutations et variations de l'ensemble des gènes de susceptibilité connus (par exemple BRCA1, BRCA2, TP53, STK11, PTEN, ATM, PALB2, CHEK2, BR1P1 et les alleles de faible penetrance identifiés récemment) ne seraient responsables que d'un maximum de 30% des cas de cancers clairement familiaux. Dans cette thèse, la contribution de certains gènes a été investiguée dans une cohorte de femmes provenant de la population canadienne française et présentant des évidences claires de l'implication forte de facteurs génétiques de susceptibilité non reliés à BRCA1 ou BRCA2. Notre étude concerne les gènes candidats ZBRK1 (Zinc finger and BRCA1-interacting protein with KRAB domain 1), GADD45A (Growth arrest and DNA-damage-inducible alpha) et NBS1 (Nijmegen breakage syndrome 1). Notre analyse de ZNF350/ZBRK1 a permis de mettre en évidence trois haplotypes modulant de façon significative le risque de cancer du sein dans notre population. Parmi ceux-ci, deux pourraient être associés à un effet protecteur (p=0.01135 et p=0.00268) alors qu'un autre haplotype est lié à une augmentation du risque (p=0.00143). Dans le cas de GADD45A, nous avons identifié un haplotype commun démontrant une fréquence plus élevée dans le groupe contrôle, bien que cette association soit faible. En ce qui concerne NBN, le variant du promoteur c.-242-l lOdelAGTA est significativement surreprésenté dans notre groupe de femmes atteintes. Des essais de type gène luciférase rapporteur n'ont pas démontré de variation d'expression dans la lignée cellulaire de cancer du sein MCF-7, mais ont indiqué une réduction de l'expression dans les lignées cellulaires HEK293 et LNCaP. Ces résultats indiquent qu'il est possible que des variations de ces gènes, bien que n'étant pas très fréquentes, soient impliquées dans la susceptibilité au cancer du sein dans notre population et des études plus approfondies sur de grandes cohortes seront nécessaires afin de confirmer ou infirmer nos résultats.
  • PublicationAccès libre
    A rare UGT2B7 variant creates a novel N-glycosylation site at codon 121 with impaired enzyme activity
    (American Society for Pharmacology and Experimental Therapeutics, 2016-09-12) Benoît-Biancamano, Marie-Odile; Desjardins, Sylvie; Guillemette, Chantal; Girard-Bock, Camille; Villeneuve, Lyne
    UDP-glucuronosyltransferase (UGT) superfamily are glycoproteins resident of the endoplasmic reticulum membranes that undergo post-translational modifications (PTM). UGT2B7 is of particular interest because of its action on a wide variety of drugs. Most studies currently survey common variants and are only examining a small fraction of the genetic diversity. However, rare variants (frequency <1%) might have significant effect as they are predicted to greatly outnumber common variants in the human genome. Here, we discovered a rare single nucleotide UGT2B7 variant of potential pharmacogenetic relevance that encodes a nonconservative amino acid substitution at codon 121. This low-frequency variation, found in two individuals of a population of 305 healthy volunteers, leads to the translation of an asparagine (Asn) instead of an aspartic acid (Asp) (UGT2B7 p.D121N). This amino acid change was predicted to create a putative N-glycosylation motif NX(S/T) subsequently validated upon endoglycosidase H treatment of microsomal fractions and inhibition of N-glycosylation of endogenously produced UGT2B7 with tunicamycin from HEK293 cells. The presence of an additional N-linked glycan on the UGT2B7 enzyme, likely affecting proper protein folding, resulted in a significant decrease, respectively by 49 and 40%, in the formation of zidovudine and mycophenolic acid glucuronides. A systematic survey of the dbSNP database uncovered 32 rare and naturally occurring missense variations predicted to create or disrupt N-glycosylation sequence motifs in the other UGT2B enzymes. Collectively, these variants have the potential to increase the proportion of variance explained in the UGT pathway due to changes in PTM such as N-linked glycosylation with consequences on drug metabolism.
  • PublicationAccès libre
    Endogenous protein interactome of human UDP-glucuronosyltransferases exposed by untargeted proteomics
    (Frontiers Research Foundation, 2017-02-03) Rouleau, Michèle; Desjardins, Sylvie; Audet-Delage, Yannick; Guillemette, Chantal; Rouleau, Mélanie; Girard-Bock, Camille
    The conjugative metabolism mediated by UDP-glucuronosyltransferase enzymes (UGTs) significantly influences the bioavailability and biological responses of endogenous molecule substrates and xenobiotics including drugs. UGTs participate in the regulation of cellular homeostasis by limiting stress induced by toxic molecules, and by controlling hormonal signaling networks. Glucuronidation is highly regulated at genomic, transcriptional, post-transcriptional and post-translational levels. However, the UGT protein interaction network, which is likely to influence glucuronidation, has received little attention. We investigated the endogenous protein interactome of human UGT1A enzymes in main drug metabolizing non-malignant tissues, where UGT expression is most prevalent, using an unbiased proteomics approach. Mass spectrometry analysis of affinity-purified UGT1A enzymes and associated protein complexes in liver, kidney and intestine tissues revealed an intricate interactome linking UGT1A enzymes to multiple metabolic pathways. Several proteins of pharmacological importance such as transferases (including UGT2 enzymes), transporters and dehydrogenases were identified, upholding a potential coordinated cellular response to small lipophilic molecules and drugs. Furthermore, a significant cluster of functionally related enzymes involved in fatty acid ß-oxidation, as well as in the glycolysis and glycogenolysis pathways were enriched in UGT1A enzymes complexes. Several partnerships were confirmed by co-immunoprecipitations and co-localization by confocal microscopy. An enhanced accumulation of lipid droplets in a kidney cell model overexpressing the UGT1A9 enzyme supported the presence of a functional interplay. Our work provides unprecedented evidence for a functional interaction between glucuronidation and bioenergetic metabolism.