Pierre Leclerc

Pierre Leclerc
Laval University | ULAVAL · Centre de Recherche en Reproduction Développement et Santé Intergénérationnelle (CRDSI)

PhD

About

102
Publications
7,065
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
4,673
Citations

Publications

Publications (102)
Article
Spermatozoa are highly specialized cells whose fertilizing and motility functions highly depend on intracellular Ca2+‐mediated events and protein posttranslational modifications like phosphorylation. Our group previously identified PPEF1, the Ser/Thr phosphatase with EF‐hand domain 1, among calmodulin‐affinity pulled down sperm proteins. As the mam...
Article
Calmodulin is a small, highly conserved acidic protein present at high levels in spermatozoa that mediates numerous intracellular Ca2+ -dependent events. Sperm motility and fertilizing ability results from an array of biochemical pathways under Ca2+ control, in which the importance of calmodulin is not fully understood. The role of calmodulin in sp...
Article
Sperm Adhesion Molecule 1 (SPAM1) is a sperm protein possessing a hyaluronidase domain in its N-terminus and a zona pellucida binding domain in its C-terminus. Our previous studies showed that bovine spermatozoa potentially have 2 SPAM1 isoforms that present different C-terminal domains, different origins (testis and epididymis), and different loca...
Article
Artificial insemination is well-established in dairy cattle, with sires housed in commercial studs for processing. In some species, however, sires located on-farm are used for artificial insemination by shipping their semen to an off-site laboratory for processing within 24 h of collection. To expedite semen transport from the farm to laboratory, p...
Article
Cholesterol-loaded cyclodextrin (CLC) is known to improve ram sperm cryosurvival. This study expands on previous research to: (1) determine the mechanism by which CLC improves ram sperm cryosurvival and (2) compare the efficiency of a novel, skim milk-based extender containing CLC to a traditional egg yolk-based extender. Hypothesis #1 was that CLC...
Article
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 i...
Article
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 spermatoz...
Article
Full-text available
The mammalian oviduct synthesizes and secretes a major glycoprotein known as oviductin (OVGP1) which has been shown to interact with gametes and early embryos. We report here the use of recombinant DNA technology to produce, for the first time, the secretory form of human OVGP1 in HEK293 cells. HEK293 colonies stably expressing recombinant human OV...
Article
In mammals, adenosine 3', 5'-cyclic monophosphate (cAMP) is known to play highly important roles in sperm motility and acrosomal exocytosis. It is known to act through protein phosphorylation via PRKA and through the activation of guanine nucleotide exchange factors like EPAC. Sperm intracellular cAMP levels depend on the activity of adenylyl cycla...
Data
Sequence alignment of one of the clones obtained in our 5’-RLM experiment with the sequence of PDE10A transcript variant X3. (PDF)
Data
Sequence alignment of one of the clones obtained in our 5’-RLM experiment with the sequence of PDE10A transcript variant X5. (PDF)
Data
Sequence alignment of one of the clones obtained in our 5’-RLM experiment with the sequence of PDE10A transcript variant X5. The clone lacks a stretch of 5 nucleotides (GGTAT) that causes a shift in the position of the starting Met residue and, therefore, of the open reading frame. (PDF)
Data
Sequence alignment of one of the clones obtained in our 5’-RLM experiment with the sequence of PDE10A transcript variant X5. Clones’ sequence from nucleotide 1–102 is present in the genomic sequence but might come from mis-spliced RNA, as for the sequence from nucleotide 608–668. Note the absence of 5 nucleotides (GGTAT; nucleotides 176–180 of tran...
Data
Sequence alignment of one of the clones obtained in our 5’-RLM experiment with the sequence of PDE10A transcript variant X5. Clones’ sequence from nucleotide 9–155 is present in the genomic sequence but might come from mis-spliced RNA. The stretch from nucleotides 9 to 180 of transcript variant X5 is missing from these clones. (PDF)
Article
The success of semen cryopreservation depends on sperm membrane integrity and function after thawing. Cholesterol-loaded cyclodextrin (CLC) is used for in vitro incorporation of cholesterol to protect cells against cold temperatures. We hypothesized that CLC treatment also enhances sperm cholesterol content to increase tolerance to osmotic shock an...
Article
We previously showed that Stattic V (Stat3 inhibitory compound V) reduces human sperm motility and cellular ATP levels, increases intracellular Ca(2+) concentration, and promotes mitochondrial membrane depolarization resulting in increased levels of extracellular reactive oxygen species (ROS). As these alterations in cellular function are highly si...
Article
Full-text available
Binder of SPerm (BSP) proteins are a family of proteins expressed exclusively in the male reproductive tract (seminal vesicles or epididymis) of several mammalian species. They are known to promote capacitation, a sperm maturation step essential for fertilization. Our recent studies have shown that in human, the Binder of SPerm Homolog 1 (BSPH1) is...
Article
Binder of SPerm (BSP) proteins are a family of proteins expressed exclusively in the male reproductive tract (seminal vesicles or epididymis) of several mammalian species. They are known to promote capacitation, a sperm maturation step essential for fertilization. Our recent studies have shown that in human, the Binder of SPerm Homolog 1 (BSPH1) is...
Article
We have recently shown that many mediators of the JAK/STAT signaling pathway are present in ejaculated human spermatozoa. Among them, STAT3 is detected mainly in membranes and flagellar cytoskeletal fractions. In order to determine the importance of STAT3-mediated signaling, sperm were incubated with Stattic V, a specific inhibitor. Effects on moti...
Article
Full-text available
Previously, we showed that epididymal sperm binding protein 1 (ELSPBP1) characterizes spermatozoa already dead before ejaculation in bovine. In this study, we investigated the presence of ELSPBP1 in bull genital tract as well as its acquisition by spermatozoa during epididymal transit. As assessed by real-time RT-PCR, ELSPBP1 was highly expressed i...
Article
On Monday, May 14, 2012, Dr. Claude Gagnon passed away after a long fight against Parkinson's disease. Claude was one of the outstanding and most respected reproductive biologists worldwide. His fundamental contributions to our understanding of sperm biology will withstand the test of time, and his service to the scientific community will serve as...
Article
Full-text available
On Monday, May 14, 2012, Dr. Claude Gagnon passed away after a long fight against Parkinson's disease. Claude was one of the outstanding and most respected reproductive biologists worldwide. His fundamental contributions to our understanding of sperm biology will withstand the test of time, and his service to the scientific community will serve as...
Article
Full-text available
Previously, we showed that binder of sperm 1 (BSP1) and epididymal sperm binding protein 1 (ELSPBP1) proteins are more abundant in the immotile bovine sperm subpopulation following cryopreservation. In this study, we investigated the association of BSP1 and ELSPBP1 with sperm in relation to their ability to survive the cryopreservation process. Fre...
Article
Full-text available
It is well established that syncytium formation involves the fusion of mononucleated trophoblasts into a multinucleated structure and the secretion of hormonal factors, such as human chorionic gonadotropin (hCG). These morphological and biochemical changes are regulated by a plethora of ligands, which upon binding to specific receptors trigger the...
Article
In their journey to acquire the ability to fertilize the egg, numerous intracellular signaling systems are activated in spermatozoa, leading to an increase in protein tyrosine phosphorylation. Although the JAK/STAT signaling pathway is usually associated with the activation of transcription of specific genes, our laboratory previously demonstrated...
Article
The secretory cells lining the lumen of mammalian oviducts synthesize and secrete a major glycoprotein known as oviduct-specific glycoprotein (OGP) or oviductin which has been shown to interact with gametes and early embryos. We report here the use of recombinant DNA technology to produce human OGP in HEK-293 cells. A full-length cDNA clone of huma...
Article
The objective of this case report was to identify the cause of apparent idiopathic infertility in a Red Angus (beef) bull. Semen was collected by electroejaculation and submitted to a series of assays, including evaluation of sperm motility by computer-assisted sperm analysis (CASA), sperm morphology and DNA integrity, semen cryopreservation, AI, I...
Article
An increase in protein tyrosine phosphorylation occurs during sperm capacitation in numerous species. The involvement of Src-related tyrosine kinases in this phenomenon has been demonstrated using different inhibitors specifically targeting this family of enzymes. In mammals, this group of nonreceptor tyrosine kinases is made up of 8 members with s...
Article
Full-text available
Intrinsic factors such as proteins modulate the fertilising ability of male gametes. We compared detergent-extracted sperm protein composition of bulls with different fertility indexes in order to highlight putative fertility markers of sperm. Frozen semen from 23 Holstein bulls with documented fertility was used. According to their 'fertility solu...
Article
The deduced amino acid sequence of bull sperm, SPAM1, suggests that it possesses a transmembrane domain between the hyaluronidase and the putative zona pellucida (ZP) binding domains. The objective of this study was to determine the orientation and localization of SPAM1 in order to understand how it could fulfill these two roles. We report that two...
Article
We identified an 80 kDa bull sperm protein (p80) that possesses homology with the Sperm adhesion molecule 1 (Spam1), a GPI-anchored glycoprotein conserved amongst mammals that is required for fertilization. Since bovine Spam1 had not been identified, the aim of this project was to determine if p80 is the bovine Spam1 and to test the hypothesis that...
Article
An increase in protein tyrosine phosphorylation has been shown to occur during sperm capacitation. The effects of tyrosine kinase inhibitors strongly suggest the involvement of src-related kinase in this phenomenon. Our group has recently reported the presence and activity of SRC in human spermatozoa. This kinase is present both in the acrosomal re...
Article
Estrogen is found in high concentrations in the excurrent duct, where it regulates the expression of genes involved in water reabsorption. Estrogen sulfotransferase (EST) is a cytosolic enzyme that catalyzes specific sulfonation with a high affinity for estrogens. Because sulfated estrogens do not bind to estrogen receptors, they are considered to...
Article
Molecular chaperones of the heat shock proteins (HSP) family are important in numerous cellular processes. In this study, the expression of Hsp60 and Grp78 proteins was investigated in the male reproductive tract. The cellular distribution of Hsp60 and Grp78 proteins was analysed in the human testis and epididymis by immunohistochemical approaches....
Article
Full-text available
In the present study, the viability, intracellular pH (pHi), cAMP ([cAMP]i), calcium concentration and protein phosphotyrosine content were evaluated in relation to the acrosomal and capacitation status of freshly ejaculated bull spermatozoa. These parameters were evaluated before and after incubation with the capacitation inducer heparin, the phos...
Article
Full-text available
Although semen cryopreservation is widely and commonly used in the bovine breeding industry, half the spermatozoa do not survive and most of those that do survive undergo numerous physiological changes that affect their fertilising ability. The aim of the present study was to determine how cryopreservation affects the intracellular events involved...
Article
SRC-related tyrosine kinases are suggested to play a role in the increase of sperm protein phosphotyrosine content that occurs during capacitation. In our laboratory, we previously demonstrated that the SRC-related tyrosine kinase YES1 (also known as c-YES) is present in human spermatozoa. However, since it is negatively regulated by Ca(2+), whose...
Article
In bull testicular haploid germ cells, an mRNA encoding for hck was detected in addition to another one encoding for hck-tr, a truncated form of the tyrosine kinase hck. As the transcripts were expressed in spermatids, we tried to determine whether hck-tr is present in mature bovine spermatozoa. Two polyclonal antibodies were produced against pepti...
Article
Full-text available
Within the female genital tract, spermatozoa undergo a series of membranous and intracellular transformations to become competent at fertilizing the oocyte. In the bovine, previous studies have shown that two oviductal proteins, heat shock protein 60 (Hsp60) and glucose regulated protein 78 (Grp78), bind to spermatozoa and may be involved in this a...
Article
To evaluate the effect of macrophage migration inhibitory factor (MIF) on sperm capacitation, a maturational process that occurs in the female reproductive tract and enables spermatozoa to become fully competent at fertilizing the oocyte. Incubation of Percoll-washed spermatozoa with varying concentrations of human recombinant MIF or fetal cord ser...
Article
Full-text available
Upon binding to the egg's zona pellucida, capacitated spermatozoa will undergo a calcium-dependent exocytotic event called acrosome reaction. During this process, Ca2+ depletion from internal stores is followed by an important rise in [Ca2+]i due to a massive Ca2+ influx. Previous reports have shown that the acrosome can act as a Ca2+ store and tha...
Article
Full-text available
Various histone acetylases (HATs) play a critical role in the regulation of gene expression, but the precise functions of many of those HATs are still unknown. Here we provide evidence that MYST4, a known HAT, may be involved in early mammalian gametogenesis. Although MYST4 mRNA transcripts are ubiquitous, protein expression was restricted to selec...
Article
Numerous sperm proteins have been identified on the basis of their increase in tyrosine phosphorylation during capacitation. However, the tyrosine kinases present in spermatozoa that are responsible for this phosphorylation remain unknown. As spermatozoa are devoid of transcriptional and translational activities, molecular biology approaches might...
Article
To evaluate sperm cryopreservation-induced injuries using sperm plasma membrane protein P34H and alpha-tubulin as two different subcellular compartment markers. Prospective experimental study. Academic hospital research center and fertility clinic. Semen samples obtained from healthy donors attending the fertility clinic. Sperm samples were either...
Article
Protein tyrosine phosphorylation is a process that has been studied worldwide during sperm capacitation and acrosomal exocytosis events. Although few capacitation-induced phosphotyrosine-containing proteins have been identified, little is known about the tyrosine kinases directly involved in this post-translational modification. Different studies f...
Article
We have identified an 80 kDa protein in ejaculated bull spermatozoa (p80) which is found in acrosomal and post-acrosomal areas of the head. It has a hyaluronidase activity and shares homologies with PH-20, a sperm surface glycoprotein involved in sperm-egg interaction. The aim of the present study was to characterize bull sperm p80 protein at the n...
Article
Mammalian sperm must undergo capacitation, a preparation period in the female reproductive tract or in vitro, in order to fertilize. We have previously described a Mr 32 000 tyrosine phosphorylated protein, "p32," that appears in pig sperm during capacitation. The identity of p32 remains unknown; if and how it is involved during capacitation is not...
Article
Full-text available
In order to become fully competent at fertilizing the oocyte, spermatozoa must undergo the maturational process of capacitation during their journey in the female reproductive tract. Endometrial cells secrete an array of growth factors that can affect spermatozoa. Among these factors, it has been previously demonstrated that interleukin-6 (IL-6) af...
Article
It is generally accepted that sperm capacitation is associated with the protein kinase A-mediated appearance of tyrosine phosphoproteins, although the substrates and kinase(s) involved have not been identified. We described a Mr 32,000 tyrosine phosphoprotein, "p32", appearing in porcine sperm coincident with capacitation. We also discovered a tyro...
Article
Upon their transit through the female genital tract, bovine spermatozoa bind to oviduct epithelial cells, where they are maintained alive for long periods of time until fertilization. Although carbohydrate components of the oviduct epithelial cell membrane are involved in these sperm/oviduct interactions, no protein candidate has been identified to...
Article
Sperm capacitation is regulated by multiple pathways that also control sperm motility and tyrosine (Tyr) phosphorylation of several sperm proteins. Among the reported pathways, phosphoinositide 3-kinase (PI3K) signaling and its role in modulating sperm postejaculatory changes and motility remain elusive. It was shown that wortmannin, a selective in...
Article
After ejaculation, mammalian sperm must undergo a preparation period known as "capacitation" to become capable of fertilizing the oocyte. Although physiological capacitation occurs in the female genital tract, the process can be reproduced in vitro by incubation in appropriate media. However, the signaling events regulating capacitation are poorly...
Article
Modern cloning methods have become an important technology in artificial insemination which is used to create and maintain pools of genetically superior bull semen. In this study, semen from four identical quadruplet bulls (Q(1), Q(2), Q(3), and Q(4)) produced by blastomere separation was analyzed to evaluate the differences in reproductive potenti...
Article
Full-text available
During human sperm capacitation, an increase in phosphotyrosine content of specific proteins results partially from an increase in the intracellular free Ca(2+) concentrations. In the present study, the inter-regulation between protein phosphotyrosine content and the intracellular Ca(2+) concentration during the thapsigargin treatment of capacitate...
Article
Phosphodiesterases (PDEs) are enzymes that degrade cyclic nucleotides. The calcium-calmodulin dependent PDE type 1 (PDE 1) and the cyclic adenosine monophosphate (cAMP)-specific PDE type 4 (PDE 4) have been implicated in sperm function. We tested the hypothesis that specific PDEs regulate capacitation of bovine sperm in a manner independent of thos...
Article
An increase in the concentration of intracellular free Ca2+ and in the phosphotyrosine content of specific proteins characterizes human sperm capacitation. Whether tyrosine phosphorylation regulates the intracellular free Ca2+ concentration through modulation of Ca2+-ATPase activity or the phosphotyrosine content is under Ca2+ regulation was invest...
Article
During the process of capacitation, spermatozoa go through a whole set of signaling cascade events in order to become fully competent at fertilizing the egg. An increase in sperm protein tyrosine phosphorylation has been described during this final maturational event in different animal species as well as in humans. Although the phosphotyrosine con...