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, Christine

En cours de chargement...
Photo de profil

Adresse électronique

Date de naissance

Projets de recherche

Structures organisationnelles

Fonction

Nom de famille

Guillemette

Prénom

Christine

Affiliation

Université Laval. Département d'obstétrique et de gynécologie

ISNI

ORCID

Identifiant Canadiana

ncf13730496

person.page.name

Résultats de recherche

Voici les éléments 1 - 8 sur 8
  • PublicationRestreint
    Activation of 5′ adenosine monophosphate-activated protein kinase blocks cumulus cell expansion through inhibition of protein synthesis during in vitro maturation in swine
    (Oxford University Press, 2014-08-01) Santiquet, Nicolas; Richard, François J.; Guillemette, Christine; Laforest, Martin; Gilchrist, Robert B.; Sasseville, Maxime
    The serine/threonine kinase 5′ adenosine monophosphate-activated protein kinase (AMPK), a heterotrimeric protein known as a metabolic switch, is involved in oocyte nuclear maturation in mice, cattle, and swine. The present study analyzed AMPK activation in cumulus cell expansion during in vitro maturation (IVM) of porcine cumulus-oocyte complexes (COC). 5-Aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) is a well-known activator of AMPK. It inhibited oocyte meiotic resumption in COC. Moreover, cumulus cell expansion did not occur in the presence of AICAR, demonstrating its marked impact on cumulus cells. Activation of AMPK was supported by AICAR-mediated phosphorylation of alpha AMPK subunits. Furthermore, the presence of AICAR increased glucose uptake, a classical response to activation of this metabolic switch in response to depleted cellular energy levels. Neither nuclear maturation nor cumulus expansion was reversed by glucosamine, an alternative substrate in hyaluronic acid synthesis, through the hexosamine biosynthetic pathway, which ruled out possible depletion of substrates. Both increased gap junction communication and phosphodiesterase activity in COC are dependent on protein synthesis during the initial hours of IVM; however, both were inhibited in the presence of AICAR, which supports the finding that activation of AMPK by AICAR mediated inhibition of protein synthesis. Moreover, this protein synthesis inhibition was equivalent to that of the well-known protein synthesis inhibitor cycloheximide, as observed on cumulus expansion and protein concentration. Finally, the phosphorylation level of selected kinases was investigated. The pattern of raptor phosphorylation is supportive of activation of AMPK-mediated inhibition of protein synthesis. In conclusion, AICAR-mediated AMPK activation in porcine COC inhibited cumulus cell expansion and protein synthesis. These results bring new considerations to the importance of this kinase in ovarian physiology and to the development of new oocyte culture medium.
  • PublicationRestreint
    Active 3'–5' cyclic nucleotide phosphodiesterases are present in detergent-resistant membranes of mural granulosa cells
    (CSIRO, 2016-01-04) Bergeron, Annick; Richard, François J.; Guillemette, Christine; Sirard, Marc-André
    Lipids rafts are specialised membrane microdomains involved in cell signalling that can be isolated as detergent-resistant membranes (DRMs). The second messenger cyclic AMP (cAMP) has a central role in cell signalling in the ovary and its degradation is carried out by the phosphodiesterase (PDE) enzyme family. We hypothesised that PDEs could be functionally present in the lipid rafts of porcine mural granulosa cell membranes. PDE6C, PDE8A and PDE11A were detected by dot blot in the DRMs and the Triton-soluble fraction of the mural granulosa cells membrane and the cytosol. As shown by immunocytochemistry, PDEs showed clear immunostaining in mural granulosa cell membranes and the cytosol. Interestingly, cAMP-PDE activity was 18 times higher in the DRMs than in the Triton-soluble fraction of cell membranes and was 7.7 times higher in the cytosol than in the DRMs. cAMP-PDE activity in mural granulosa cells was mainly contributed by the PDE8 and PDE11 families. This study shows that PDEs from the PDE8 and PDE11 families are present in mural granulosa cells and that the cAMP-PDE activity is mainly contributed by the cytosol. In the cell membrane, the cAMP-PDE activity is mainly contributed by the DRMs. In addition, receptors for prostaglandin E2 and LH, two G-protein-coupled receptors, are present in lipid rafts and absent from the non-raft fraction of the granulosa cell membrane. These results suggest that in these cells, the lipid rafts exist as a cell-signalling platform and PDEs are one of the key enzyme families present in the raft.
  • PublicationRestreint
    Papaverine-sensitive phosphodiesterase activity is measured in bovine spermatozoa
    (Wiley, 2016-11-16) Vigneault, Christian; Poulin, Marie-Pier; Bergeron, Annick; Leclerc, Pierre; Richard, François J.; Sullivan, Robert; Hébert, Audrey; Guillemette, Christine; Aragon, Juan Pablo; Laroche, A.; Blondin, Patrick.
    Cyclic adenosine monophosphate (cAMP) plays a crucial role as a signaling molecule for capacitation, motility, and acrosome reaction in mammalian spermatozoa. It is well‐known that cAMP degradation by phosphodiesterase (PDE) enzyme has a major impact on sperm functions. This study was undertaken to characterize cAMP‐PDE activity in bovine spermatozoa. Total cAMP‐PDE activity in cauda epididymal and ejaculated spermatozoa was 543.2 ± 49.5 and 1252.6 ± 86.5 fmoles/min/106 spermatozoa, respectively. Using different family‐specific PDE inhibitors, we showed that in cauda epididymal and ejaculated spermatozoa, the major cAMP‐PDE activity was papaverine‐sensitive (44.5% and 57.5%, respectively, at 400 nm, papaverine is a specific inhibitor of the PDE10 family). These data are supporting the functional presence of PDE10 in bovine spermatozoa and were further confirmed by western blot to be PDE10A. Using immunocytochemistry, we showed immunoreactive signal for PDE10A present on the post‐acrosomal region of the head and on the flagella of ejaculated spermatozoa. Using papaverine, we showed that it promotes tyrosine phosphorylation of sperm proteins, phosphorylation of Erk1 and Erk2, and Ca²+ release from Ca²+ store. These results suggest that PDE10 is functionally present in bovine spermatozoa and is affecting different molecular events involved in capacitation, most probably by cAMP local regulation.
  • PublicationRestreint
    New elements in the c-type natriuretic peptide signaling pathway inhibiting swine in vitro oocyte meiotic resumption
    (Academic Press, 2014-07-01) Djender, Nadjib; Papillon-Dion, Émilie; Santiquet, Nicolas; Richard, François J.; Guillemette, Christine
    C-type natriuretic peptide (CNP) and its cognate receptor, natriuretic peptide receptor (NPR) B, have been shown to promote cGMP production in granulosa/cumulus cells. Once transferred to the oocyte through the gap junctions, the cGMP inhibits oocyte meiotic resumption. CNP has been shown to bind another natriuretic receptor, NPR-C. NPR-C is known to interact with and degrade bound CNP, and has been reported to possess signaling functions. Therefore, NPR-C could participate in the control of oocyte maturation during swine in vitro maturation (IVM). Here, we examine the effect of CNP signaling on meiotic resumption, the amount of cGMP and gap junctional communication (GJC) regulation during swine IVM. The results show an inhibitory effect of CNP in inhibiting oocyte meiotic resumption in follicle-stimulating hormone (FSH)-stimulated IVM. We also found that an NPR-C-specific agonist (cANP[4–23]) is likely to play a role in maintaining meiotic arrest during porcine IVM when in the presence of a suboptimal dose of CNP. Moreover, we show that, even if CNP can increase intracellular concentration of cGMP in cumulus-oocyte complexes, cANP(4–23) had no impact on cGMP concentration, suggesting a potential cGMP-independent signaling pathway related to NPR-C activation. These data support a potential involvement of cANP(4–23) through NPR-C in inhibiting oocyte meiotic resumption while in the presence of a suboptimal dose of CNP. The regulation of GJC was not altered by CNP, cANP(4–23), or the combination of CNP and cANP(4–23), supporting their potential contribution in sending signals to the oocytes. These findings offer promising insights in to new elements of the signaling pathways that may be involved in inhibiting resumption of meiosis during FSH-stimulated swine IVM.
  • PublicationRestreint
    Cyclic nucleotide phosphodiesterases in human spermatozoa and seminal fluid : presence of an active PDE10A in human spermatozoa
    (Elsevier, 2016-11-09) Leclerc, Pierre; Richard, François J.; Guillemette, Christine; Goupil, Serge; Maréchal, Loïze; Blondin, Patrick.
    Background: Cyclic adenosine monophosphate (cAMP) plays a crucial role as a signaling molecule for sperm functions such as capacitation, motility and acrosome reaction. It is well known that cAMP degradation by phosphodiesterase (PDE) enzyme has a major impact on sperm functions. The present study was undertaken to characterize cAMP-PDE activity in human semen. Methods: cAMP-PDE activity was measured in human sperm and seminal plasma using family specific PDE inhibitors. Three sperm fractionation methods were applied to assess cAMP-PDE activity in spermatozoa. Western blots were used to validate the presence of specific family in sperm and seminal plasma. Results: Using three sperm fractionation methods, we demonstrated that in human sperm, the major cAMP-PDE activity is papaverine-sensitive and thus ascribed to PDE10. In seminal plasma, total cAMP-PDE activity was 1.14 ± 0.39 fmol of cAMP hydrolyzed per minute per μg of protein. Using specific inhibitors, we showed that the major cAMP-PDE activity found in human seminal plasma is ascribed to PDE4 and PDE11. Western blot analysis, immunoprecipitation with a specific monoclonal antibody, and mass spectrometry confirmed the presence of PDE10 in human spermatozoa. Conclusion: This study provides the first demonstration of the presence of functional PDE10 in human spermatozoa and functional PDE4 and PDE11 in human seminal plasma. General significance: Since the contribution of cyclic nucleotides in several sperm functions is well known, the finding that PDE10 is an active enzyme in human spermatozoa is novel and may lead to new insight into fertility.
  • PublicationRestreint
    Characterization of cAMP-phosphodiesterase activity in bovine seminal plasma
    (American Society of Andrology, 2016-08-27) Bergeron, Annick; Richard, François J.; Sullivan, Robert; Hébert, Audrey; Guillemette, Christine; Aragon, Juan Pablo; Blondin, Patrick.
    The second messenger cyclic adenosine monophosphate (cAMP) has a central role in sperm physiology. Extracellular cAMP can besequentially degraded into 50AMP and adenosine by ecto-phosphodiesterases (ecto-PDE) and ecto-nucleotidases, a phenomenoncalled extracellular cAMP-adenosine pathway. As cAMP-adenosine pathway is involved in sperm capacitation, we hypothesize thatextracellular PDEs are functionally present in seminal plasma. Exclusively measuring cAMP-PDE activity, total activity in bovineseminal plasma was 10.1 1.5 fmoles/min/lg. Using different family-specific PDE inhibitors, we showed that in seminal plasma,the major cAMP-PDE activity was papaverine sensitive (47.5%). These data support the presence of PDE10 in bovine seminal plasmaand was further confirmed by western blot. In epididymal fluid, total cAMP-PDE activity was 48.2 14.8 fmoles/min/lg and weshowed that the major cAMP-PDE activity was 3-isobutyl-methylxanthine insensitive and thus ascribed to PDE8 family. PDE10AmRNAs were found in the testis, epididymis, and seminal vesicles. cAMP-PDE activity is present in bovine seminal plasma and epi-didymal fluid. The results suggest a role for ecto-PDEs present in those fluids in the signaling pathways involved in sperm functions.
  • PublicationRestreint
    Active 3'-5' cyclic nucleotide phosphodiesterases are present in detergent-resistant membranes of mural granulosa cells
    (CSIRO, 2016-01-04) Bergeron, Annick; Richard, François J.; Guillemette, Christine; Sirard, Marc-André
    Lipids rafts are specialised membrane microdomains involved in cell signalling that can be isolated as detergent-resistant membranes (DRMs). The second messenger cyclic AMP (cAMP) has a central role in cell signalling in the ovary and its degradation is carried out by the phosphodiesterase (PDE) enzyme family. We hypothesised that PDEs could be functionally present in the lipid rafts of porcine mural granulosa cell membranes. PDE6C, PDE8A and PDE11A were detected by dot blot in the DRMs and the Triton-soluble fraction of the mural granulosa cells membrane and the cytosol. As shown by immunocytochemistry, PDEs showed clear immunostaining in mural granulosa cell membranes and the cytosol. Interestingly, cAMP-PDE activity was 18 times higher in the DRMs than in the Triton-soluble fraction of cell membranes and was 7.7 times higher in the cytosol than in the DRMs. cAMP-PDE activity in mural granulosa cells was mainly contributed by the PDE8 and PDE11 families. This study shows that PDEs from the PDE8 and PDE11 families are present in mural granulosa cells and that the cAMP-PDE activity is mainly contributed by the cytosol. In the cell membrane, the cAMP-PDE activity is mainly contributed by the DRMs. In addition, receptors for prostaglandin E2 and LH, two G-protein-coupled receptors, are present in lipid rafts and absent from the non-raft fraction of the granulosa cell membrane. These results suggest that in these cells, the lipid rafts exist as a cell-signalling platform and PDEs are one of the key enzyme families present in the raft.
  • PublicationRestreint
    Characterization of FSH signalling networks in bovine cumulus cells : a perspective on oocyte competence acquisition
    (Oxford University Press, 2015-06-24) Khan, Daulat Raheem; Richard, François J.; Guillemette, Christine; Sirard, Marc-André
    Understanding the mechanisms regulating oocyte developmental competence is essential to enhance the clinical efficiency of assisted reproduction. FSH orchestrates the acquisition of oocyte competence, both in vivo and in vitro. Multiple pathways are implicated in FSH signalling; however, their precise coordination remains unresolved. A robust system to investigate FSH signalling is oocyte in vitro maturation (IVM) and we have previously demonstrated better bovine embryo development after FSH addition for the first 6 h during IVM. Using this model, we investigated FSH signalling in cumulus through transcriptomic and pharmacological tools. We demonstrate modulation of cumulus transcriptome by FSH mainly through protein kinase A (PKA) and epidermal growth factor (EGF) pathways. Differentially expressed transcripts were implicated in cumulus expansion, steroidogenesis, cell metabolism and oocyte competence. FSH required rouse-sarcoma oncogene (SRC) for EGF receptor transactivation. PKA and EGF pathway crosstalk was investigated using extracellular signal-regulated kinases (ERK1/2) phosphorylation as the functional end-point. FSH enhanced ERK1/2 activation by the EGF pathway with a simultaneous diminution through PKA. More specifically, FSH increased dual specific phosphatase (DUSP1) transcripts via PKA although DUSP1 protein did not change since EGF was required to prevent degradation. Our findings implicate FSH in PKA and EGF pathway activation, which interact to maintain appropriate levels of ERK1/2 phosphorylation and eventually cumulus expansion, metabolism and steroidogenesis. Moreover, considering the implication of the EGF pathway in GDF9 and BMP15 actions, our findings suggest that FSH may have a role in modulation of the cumulus response to oocyte-secreted factors. This information has implications for improvement of IVM and hence oocyte developmental competence.