A5028790686- Reproductive Biology and Fertility
- Microtubule and mitosis dynamics
- Sperm and Testicular Function
- Ion channel regulation and function
- Pluripotent Stem Cells Research
- Plant Molecular Biology Research
- Cardiac electrophysiology and arrhythmias
- Renal and related cancers
- Cellular Mechanics and Interactions
- Ovarian function and disorders
- Ion Channels and Receptors
- Neuroscience and Neuropharmacology Research
- Receptor Mechanisms and Signaling
- CRISPR and Genetic Engineering
- Epigenetics and DNA Methylation
- Birth, Development, and Health
- Prenatal Screening and Diagnostics
- Mitochondrial Function and Pathology
- Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities
- Advanced Fluorescence Microscopy Techniques
- Genomics and Chromatin Dynamics
- Cellular transport and secretion
- Plant Genetic and Mutation Studies
- Assisted Reproductive Technology and Twin Pregnancy
- Seed Germination and Physiology
Centre National de la Recherche Scientifique
2012-2025
Université de Rennes
2013-2025
Inserm
2025
Institut de génétique et de développement de Rennes
2012-2023
Fédération de recherche en imagerie multi-modalité
2015
University College London
2002-2013
UCL Australia
2006
Université de Bordeaux
1997-2000
Mammalian oocytes are arrested at the prophase of meiosis I during fetal or postnatal development, and is resumed by preovulatory surge luteinizing hormone. The in vivo functional roles cyclin-dependent kinases (Cdks) resumption mammalian largely unknown. Previous studies have shown that deletions Cdk3, Cdk4 Cdk6 mice result viable animals with normal oocyte maturation, indicating these Cdks not essential for meiotic maturation oocytes. In addition, conventional knockout Cdk1 Cdk2 leads to...
Asymmetric meiotic divisions in mammalian oocytes rely on the eccentric positioning of spindle and remodeling overlying cortex, resulting formation small polar bodies. The mechanism this cortical polarization, exemplified by a thick F-actin cap, is poorly understood. Cdc42 major player cell polarization many systems; however, spatio-temporal dynamics activation during oocyte meiosis, its contribution to have remained elusive. In study, we investigated (Cdc42–GTP), role mouse divisions. We...
In rat portal vein myocytes, Ca 2+ signals can be generated by inositol 1,4,5-trisphosphate (InsP 3 )- and ryanodine-sensitive release channels, which are located on the same intracellular store. Using a laser scanning confocal microscope associated with patch-clamp technique, we showed that propagated waves evoked norepinephrine (in continuous presence of oxodipine) were completely blocked after internal application an anti-InsP receptor antibody. These also reduced ∼50% transformed in...
In mammalian eggs, sperm-induced Ca2+ oscillations at fertilization are the primary trigger for egg activation and initiation of embryonic development. Identifying downstream effectors that decode this unique signal is essential to understand how transition from embryo coordinated. Here, we investigated whether conventional PKCs (cPKCs) can fertilization. By monitoring dynamics GFP-labeled PKCα PKCγ in living mouse demonstrate cPKCs translocate membrane following a pattern shaped by...
A series of Ca 2+ oscillations during mammalian fertilization is necessary and sufficient to stimulate meiotic resumption pronuclear formation. It not known how effectively development continues in the absence initial signal. We have triggered parthenogenetic egg activation with cycloheximide that causes no increase, ethanol a single large or Sr oscillations. Eggs were co-treated cytochalasin D make them diploid they formed pronuclei two-cell embryos at high rates each treatment. However,...
The organismal roles of the ubiquitously expressed class I PI3K isoform p110β remain largely unknown. Using a new kinase-dead knockin mouse model that mimics constitutive pharmacological inactivation p110β, we document full leads to embryonic lethality in substantial fraction mice. Interestingly, homozygous mice survive into adulthood (maximum ~26% on mixed genetic background) have no apparent phenotypes, other than subfertility females and complete infertility males. Systemic inhibition...
The PI3K/Akt pathway is thought to regulate key steps of mammalian oogenesis, such as dormant oocyte awakening during follicular activation, meiotic resumption and maturation. Supporting evidence however indirect, PI3K activation has never been formally demonstrated, the isoforms involved have not revealed. Here, we employed fluorescent PIP3 biosensors characterize dynamics in mouse oocytes investigated contribution isoform p110α via conditional genetic ablation. Prophase showed baseline...
Asymmetric meiotic divisions in mammalian oocytes are driven by the eccentric positioning of spindle, along with a dramatic reorganization overlying cortex, including loss microvilli and formation thick actin cap. Actin polarization relies on Ran-GTP gradient centered metaphase chromosomes; however, downstream signaling cascade is not completely understood. In recent study, we have shown that Ran promotes cap via polarized activation Cdc42. The related GTPase Rac also activated fashion...
Asymmetric meiotic divisions in oocytes rely on spindle positioning close vicinity to the cortex. In metaphase II mouse oocytes, eccentric triggers cortical polarization, including build-up of an actin cap surrounded by a ring activated myosin II. While role promoting polar body formation is established, activation mechanisms and functions have remained elusive. Here, we show that requires myotonic dystrophy kinase-related Cdc42-binding kinase (MRCK), downstream polarized Cdc42. MRCK...
A series of intracellular Ca2+ oscillations are responsible for triggering egg activation and cortical granule exocytosis at fertilization in mammals. These generated by an increase inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)], which results from the hydrolysis phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)]. Using confocal imaging to simultaneously monitor plasma membrane PtdIns(4,5)P(2) single living mouse eggs we have sought establish relationship between kinetics metabolism...
Mammalian preimplantation embryos develop in the oviduct as individual entities, and can survive vitro, defined culture media lacking exogenous growth factors or serum. Therefore, early must generate intrinsic signals that promote their development survival. In other cells, activation of class I phosphoinositide 3-kinase (PI3K) is a universal mechanism to cell proliferation Here, we examined whether PI3K intrinsically activated during development. Using GFP-tagged pleckstrin homology domains...
Background information . At fertilization in mammalian eggs, the sperm induces a series of Ca 2+ oscillations via production inositol 1,4,5‐trisphosphate. Increased 1,4,5‐trisphosphate appears to be triggered by sperm‐derived PLCζ (phospholipase C‐ζ) that enters egg after gamete fusion. The specific phosphatidylinositol 4,5‐bisphosphate hydrolytic activity implies DAG (diacylglycerol) production, and hence PKC (protein kinase C) stimulation, also occurs during fertilization....
Cell fragmentation is commonly observed in human preimplantation embryos and associated with poor prognosis during assisted reproductive technology (ART) procedures. However, the mechanisms leading to cell remain largely unknown. Here, light sheet microscopy imaging of mouse reveals that inefficient chromosome separation due spindle defects, caused by dysfunctional molecular motors Myo1c or dynein, leads mitosis. Extended exposure cortex chromosomes locally triggers actomyosin contractility...
Mammalian oocyte meiotic divisions are highly asymmetric and produce a large haploid gamete 2 small polar bodies. This relies on the ability of cell to break symmetry position its spindle close cortex before anaphase occurs. In metaphase II–arrested mouse oocytes, is actively maintained parallel cortex, until fertilization triggers sister chromatid segregation rotation spindle. The latter must indeed reorient perpendicular enable cytokinesis ring closure at base body. However, mechanisms...
Localized Ca2+-release signals (puffs) and propagated Ca2+ waves were characterized in rat ureteric myocytes by confocal microscopy. puffs evoked photorelease of low concentrations Ins(1,4,5)P3 from a caged precursor acetylcholine; they also observed spontaneously Ca2+-overloaded myocytes. showed some variability amplitude, time course spatial spread, suggesting that Ins(1,4,5)P3-gated channels exist clusters containing variable numbers within these number can be recruited. Immunodetection...
Availability of voltage-gated calcium channels (Cav) at the plasma membrane is paramount to maintaining homeostasis cell. It proposed that ubiquitylation/de-ubiquitylation balance regulates density ion cell surface. Voltage-gated Cav1.2 have been found be ubiquitylated under basal conditions both in vitro and vivo. In a previous study, we shown are by neuronal precursor cell-expressed developmentally downregulated 4 (Nedd4-1) ubiquitin ligases, but identity counterpart de-ubiquitylating...
How multiple actin networks coexist in a common cytoplasm while competing for shared pool of monomers is still an ongoing question. This exemplified by meiotic maturation the mouse oocyte, which relies on dynamic remodeling distinct cortical and cytoplasmic F-actin networks. Here, we show that conserved actin-depolymerizing factor cofilin activated switch-like manner upon meiosis resumption from prophase arrest. Interfering with activation during resulted widespread elongation microvilli,...
Localized Ca2+-release signals (puffs) and propagated Ca2+ waves were characterized in rat ureteric myocytes by confocal microscopy. puffs evoked photorelease of low concentrations Ins(1,4,5)P3 from a caged precursor acetylcholine; they also observed spontaneously Ca2+-overloaded myocytes. showed some variability amplitude, time course spatial spread, suggesting that Ins(1,4,5)P3-gated channels exist clusters containing variable numbers within these number can be recruited. Immunodetection...