Publications by authors named "Messiaen S"

Few therapeutic options are available to treat COVID-19. The KEAP1/NRF2 pathway, the major redox-responsive pathway, has emerged as a potential therapeutic target for COVID-19 as it regulates redox homeostasis and inflammation that are altered during SARS-CoV-2 infection. Here, we characterized the effects of NRF2-agonist Sulfodyne, a stabilized natural Sulforaphane, in cellular and animal models of SARS-CoV-2 infection.

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Background: Human multilineage-differentiating stress enduring (Muse) cells are nontumorigenic endogenous pluripotent-like stem cells that can be easily obtained from various adult or fetal tissues. Regenerative effects of Muse cells have been shown in some disease models. Muse cells specifically home in damaged tissues where they exert pleiotropic effects.

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The generation of oocytes from induced pluripotent stem cells (iPSCs) was proven efficient with mouse cells. However, no human iPSCs have yet been reported to generate cells able to complete oogenesis. Additionally, efficient sorting of human Primordial Germ Cell- Cells (hPGC-LCs) without genomic integration of fluorescent reporter for their downstream manipulation is still lacking.

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Article Synopsis
  • Many endocrine disruptors, like Bisphenol A (BPA), negatively affect meiosis, a process crucial for healthy gamete production, leading to conditions like oocyte aneuploidy.
  • Research on BPA alternatives, such as BADGE and BPAF, reveals they also delay meiosis, increase specific foci in cells, and cause defects in gene expression and DNA integrity during oogenesis in mice.
  • The study suggests that oxidative DNA damage may be a common harmful mechanism in female meiosis caused by various environmental pollutants, highlighting the need to reevaluate the risks of mixtures of bisphenols found in our surroundings.
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Male gametogenesis involves both mitotic divisions to amplify germ cell progenitors that gradually differentiate and meiotic divisions. Centrosomal regulation is essential for both types of divisions, with centrioles remaining tightly paired during the interphase. Here, we generated and characterized the phenotype of mutant mice devoid of , a gene encoding for a docking protein for fibers linking centrioles, and characterized their phenotype.

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For decades, numerous chemical pollutants have been described to interfere with endogenous hormone metabolism/signaling altering reproductive functions. Among these endocrine disrupting substances, Bisphenol A (BPA), a widely used compound, is known to negatively impact germ and somatic cells in the testis. Physical agents, such as ionizing radiation, were also described to perturb spermatogenesis.

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Research Question: What is the impact of radiation exposure on oocyte quality and female fertility?

Design: Prepubertal mice underwent whole-body irradiation with a single dose (0.02, 0.1, 0.

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Macrophages are the principal immune cells of the epididymis and testis, but their origins, heterogeneity, development, and maintenance are not well understood. Here, we describe distinct populations of epididymal and testicular macrophages that display an organ-specific cellular identity. Combining in vivo fate-mapping, chimeric and parabiotic mouse models with in-depth cellular analyses, we found that CD64MHCII and CD64MHCII macrophage populations of epididymis and testis arise sequentially from yolk sac erythro-myeloid progenitors, embryonic hematopoiesis, and nascent neonatal monocytes.

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Article Synopsis
  • Primary ovarian insufficiency (POI) affects around 1% of women under 40, and genetic causes, including DNA repair variants, have been linked to this condition, with a case of isolated POI reported in a Turkish family.
  • Exome sequencing revealed a specific BRCA2 variant in the patient, and various functional tests indicated that this variant affects genetic repair processes, although no cancer or syndromic traits were evident.
  • The study broadens the understanding of BRCA2 mutations by linking a specific variant to isolated POI, which can influence patient management and genetic counseling strategies for those affected.
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Article Synopsis
  • In female mammals, germ cells start meiosis in the fetal ovaries, while in males, it's delayed until after birth, with retinoic acid (RA) playing a key role in this process.
  • CYP26B1, an enzyme that breaks down RA, is crucial for preventing meiosis in fetal testes, but the influence of RA in female meiosis has not been clearly demonstrated before.
  • This study shows that while CYP26B1 effectively stops meiosis in female germ cells, RA appears to enhance STRA8 expression rather than directly trigger it, suggesting more complex interactions that should prompt further research into substances that regulate meiosis.
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Background: Using an organotypic culture system termed human Fetal Testis Assay (hFeTA) we previously showed that 0.01 μM BPA decreases basal, but not LH-stimulated, testosterone secreted by the first trimester human fetal testis. The present study was conducted to determine the potential for a long-term antiandrogenic effect of BPA using a xenograft model, and also to study the effect of BPA on germ cell development using both the hFETA and xenograft models.

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Study Question: How can pre-meiotic germ cells persist in the human foetal ovary?

Summary Answer: Numerous oogonia escaping meiotic entry were retrieved throughout human ovarian development simultaneously with the expression of signalling pathways preventing meiosis, typically described in the rodent embryonic testis.

What Is Known Already: The transition from mitosis to meiosis is a key event in female germ cells that remains poorly documented in research on the human ovary. Previous reports described a strikingly asynchronous differentiation in the human female germ line during development, with the persistence of oogonia among oocytes and follicles during the second and third trimesters.

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Anti-silencing function 1 (ASF1) is an evolutionarily conserved histone H3-H4 chaperone involved in the assembly/disassembly of nucleosome and histone modification. Two paralogous genes, Asf1a and Asf1b, exist in the mouse genome. Asf1a is ubiquitously expressed and its loss causes embryonic lethality.

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Article Synopsis
  • Sexual reproduction relies on meiosis, a specialized cell division needed to create haploid gametes, and the study reveals that a new protein called MEIOC is essential for fertility and proper meiosis.
  • MEIOC's absence in mice leads to significant meiotic issues in both sexes, as it prevents degradation of meiotic transcripts and interacts with an RNA helicase that binds several meiotic mRNAs.
  • The findings suggest that meiosis requires specific stabilization of these transcripts and that the activation of meiotic processes involves both retinoic acid-dependent and independent pathways, hinting at an evolutionary conserved mechanism in multicellular animals.
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Beside its well-documented role in carcinogenesis, the function of p53 family has been more recently revealed in development and female reproduction, but it is still poorly documented in male reproduction. We specifically tested this possibility by ablating Mdm2, an E3 ligase that regulates p53 protein stability and transactivation function, specifically in Sertoli cells (SCs) using the AMH-Cre line and created the new SC-Mdm2(-/-) line. Heterozygous SC-Mdm2(-/+) adult males were fertile, but SC-Mdm2(-/-) males were infertile and exhibited: a shorter ano-genital distance, an extra duct along the vas deferens that presents a uterus-like morphology, degenerated testes with no organized seminiferous tubules and a complete loss of differentiated germ cells.

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During the last decades, many studies reported that male reproductive disorders are increasing among humans. It is currently acknowledged that these abnormalities can result from fetal exposure to environmental chemicals that are progressively becoming more concentrated and widespread in our environment. Among the chemicals present in the environment (air, water, food, and many consumer products), several can act as endocrine disrupting compounds (EDCs), thus interfering with the endocrine system.

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Absence of mitosis and meiosis are distinguishing properties of male germ cells during late fetal and early neonatal periods. Repressors of male germ cell meiosis have been identified, but mitotic repressors are largely unknown, and no protein repressing both meiosis and mitosis is known. We demonstrate here that the zinc-finger protein BNC2 is present in male but not in female germ cells.

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Fetal testis is a major target of endocrine disruptors (EDs). During the last 20 years, we have developed an organotypic culture system that maintains the function of the different fetal testis cell types and have used this approach as a toxicological test to evaluate the effects of various compounds on gametogenesis and steroidogenesis in rat, mouse and human testes. We named this test rat, mouse and human fetal testis assay.

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Meiotic recombination is a mandatory process for sexual reproduction. We identified a protein specifically implicated in meiotic homologous recombination that we named: meiosis specific with OB domain (MEIOB). This protein is conserved among metazoan species and contains single-strand DNA binding sites similar to those of RPA1.

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Rad54 is an important factor in the homologous recombination pathway of DNA double-strand break repair. However, Rad54 knockout (KO) mice do not exhibit overt phenotypes at adulthood, even when exposed to radiation. In this study, we show that in Rad54 KO mouse the germline is actually altered.

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Background: Phthalates have been shown to have reprotoxic effects in rodents and human during fetal life. Previous studies indicate that some members of the nuclear receptor (NR) superfamilly potentially mediate phthalate effects. This study aimed to assess if expression of these nuclear receptors are modulated in the response to MEHP exposure on the human fetal gonads in vitro.

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The present study was conducted to determine whether exposure to the mono-(2-ethylhexyl) phthalate (MEHP) represents a genuine threat to male human reproductive function. To this aim, we investigated the effects on human male fetal germ cells of a 10⁻⁵ M exposure. This dose is slightly above the mean concentrations found in human fetal cord blood samples by biomonitoring studies.

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The mechanisms regulating the entry into meiosis in mammalian germ cells remain incompletely understood. We investigated the involvement of the TGF-β family members in fetal germ cell meiosis initiation. Nodal, a member of the TGF-β family, and its target genes are precociously expressed in embryonic gonads and show sexual dimorphism in favor of the developing testis.

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Continuous, low-dose exposure to a phytoestrogen (1 mg/kg/day genistein) and/or to an antiandrogenic food contaminant (1 mg/kg/day vinclozolin) has been recently reported to affect male reproductive tract and fertility [1] in adults. We investigated whether alterations of the testis are already present at the end of in utero exposure using the same rat model and doses following exposure from conception to delivery. After vinclozolin exposure, we observed in the neonate a slight but significant alteration of steroidogenesis and gametogenesis with a reduction of testosterone secretion and of the number of gonocytes.

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During testis development, proliferation and death of gonocytes are highly regulated to establish a standard population of adult stem spermatogonia that maintain normal spermatogenesis. As Transforming Growth Factor beta (TGFbeta) can regulate proliferation and apoptosis, we investigated its expression and functions during testis development. We show that TGFbeta2 is only expressed in quiescent gonocytes and decreases gonocyte proliferation in vitro.

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