Pour savoir comment effectuer et gérer un dépôt de document, consultez le « Guide abrégé – Dépôt de documents » sur le site Web de la Bibliothèque. Pour toute question, écrivez à corpus@ulaval.ca.
 

Personne :
Guillemette, Chantal

En cours de chargement...
Photo de profil

Adresse électronique

Date de naissance

Projets de recherche

Structures organisationnelles

Fonction

Nom de famille

Guillemette

Prénom

Chantal

Affiliation

Université Laval. Faculté de pharmacie

ISNI

ORCID

Identifiant Canadiana

ncf13674031

person.page.name

Résultats de recherche

Voici les éléments 1 - 3 sur 3
  • 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
    Unravelling the transcriptomic landscape of the major phase II UDP-glucuronosyltransferase drug metabolizing pathway using targeted RNA sequencing
    (Nature, 2015-04-14) Lévesque, Éric; Margaillan, Guillaume; Rouleau, Michèle; Gilbert, Isabelle; Droit, Arnaud; Tourancheau, Alan; Guillemette, Chantal; Villeneuve, Lyne
    A comprehensive view of the human UDP-glucuronosyltransferase (UGT) transcriptome is a prerequisite to the establishment of an individual's UGT metabolic glucuronidation signature. Here, we uncover the transcriptome landscape of the 10 human UGT gene loci in normal and tumoral metabolic tissues by targeted RNA next-generation sequencing. Alignment on the human hg19 reference genome identifies 234 novel exon-exon junctions. We recover all previously known UGT1 and UGT2 enzyme-coding transcripts and identify over 130 structurally and functionally diverse novel UGT variants. We further expose a revised genomic structure of UGT loci and provide a comprehensive repertoire of transcripts for each UGT gene. Data also uncover a remodelling of the UGT transcriptome occurring in a tissue- and tumor-specific manner. The complex alternative splicing program regulating UGT expression and protein functions is likely critical in determining detoxification capacity of an organ and stress-related responses, with significant impact on drug responses and diseases.
  • PublicationAccès libre
    The relative protein abundance of UGT1A alternative splice variants as a key determinant of glucuronidation activity in vitro
    (American Society for Pharmacology and Experimental Therapeutics, etc., 2013-04-01) Roberge, Joannie; Guillemette, Chantal; Falardeau, Sarah-Ann; Rouleau, Mélanie; Villeneuve, Lyne
    Alternative splicing (AS) is one of the most significant components of the functional complexity of human UDP-glucuronosyltransferase enzymes (UGTs), particularly for the UGT1A gene, which represents one of the best examples of a drug-metabolizing gene regulated by AS. Shorter UGT1A isoforms [isoform 2 (i2)] are deficient in glucuronic acid transferase activity but function as negative regulators of enzyme activity through protein-protein interaction. Their abundance, relative to active UGT1A enzymes, is expected to be a determinant of the global transferase activity of cells and tissues. Here we tested whether i2-mediated inhibition increases with greater abundance of the i2 protein relative to the isoform 1 (i1) enzyme, using the extrahepatic UGT1A7 as a model and a series of 23 human embryonic kidney 293 clonal cell lines expressing variable contents of i1 and i2 proteins. Upon normalization for i1, a significant reduction of 7-ethyl-10-hydroxycamptothecin glucuronide formation was observed for i1+i2 clones (mean of 53%) compared with the reference i1 cell line. In these clones, the i2 protein content varied greatly (38–263% relative to i1) and revealed two groups: 17 clones with i2 < i1 (60% ± 3%) and 6 clones with i2 = i1 (153% ± 24%). The inhibition induced by i2 was more substantial for clones displaying i2 = i1 (74.5%; P = 0.001) compared with those with i2 < i1 (45.5%). Coimmunoprecipitation supports a more substantial i1-i2 complex formation when i2 exceeds i1. We conclude that the relative abundance of regulatory i2 proteins has the potential to drastically alter the local drug metabolism in the cells, particularly when i2 surpasses the protein content of i1.