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Gouesse RJ, Dianati E, McDermott A, Wade MG, Hales B, Robaire B, Plante I. In Utero and Lactational Exposure to an Environmentally Relevant Mixture of Brominated Flame Retardants Induces a Premature Development of the Mammary Glands. Toxicol Sci 2021; 179:206-219. [PMID: 33252648 DOI: 10.1093/toxsci/kfaa176] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In utero and prepubertal development of the mammary glands occurs minimally in a hormone independent manner until puberty where maturation of the hypothalamic-pituitary-gonadal axis drives an extensive remodeling. Nevertheless, because the immature glands contain functional hormone receptors, they are especially vulnerable to the effects of endocrine disruptors, such as brominated flame retardants (BFRs). BFRs are widespread chemicals added to household objects to reduce their flammability, and to which humans are ubiquitously exposed. We previously reported that in utero and lactational exposure to BFRs resulted in an impaired mammary gland development in peripubertal animals. Here, we assessed whether BFR-induced disruption of mammary gland development could manifest earlier in life. Dams were exposed prior to mating until pups' weaning to a BFR mixture (0, 0.06, 20, or 60 mg/kg/day) formulated according to levels found in house dust. The mammary glands of female offspring were collected at weaning. Histo-morphological analyses showed that exposure to 0.06 mg/kg/day accelerates global epithelial development as demonstrated by a significant increase in total epithelial surface area, associated with a tendency to increase of the ductal area and thickness, and of lumen area. Significant increases of the Ki67 cell proliferation index and of the early apoptotic marker cleaved caspase-9 were also observed, as well as an upward trend in the number of thyroid hormone receptor α1 positive cells. These molecular, histologic, and morphometric changes are suggestive of accelerated pubertal development. Thus, our results suggest that exposure to an environmentally relevant mixture of BFRs induces precocious development of the mammary gland.
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Affiliation(s)
| | - Elham Dianati
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, Quebec H7V 1B7, Canada
| | - Alec McDermott
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, Quebec H7V 1B7, Canada
| | - Michael G Wade
- Health Canada, Environmental Health Science and Research Bureau, Ottawa, Ontario K1A 0K9, Canada
| | - Barbara Hales
- Faculty of Medicine, Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Bernard Robaire
- Faculty of Medicine, Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada.,Faculty of Medicine, Department of Obstetrics & Gynecology, McGill University, Montreal, Quebec H4A 3J1, Canada
| | - Isabelle Plante
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, Quebec H7V 1B7, Canada
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Gouesse RJ, Lavoie M, Dianati E, Wade MG, Hales BF, Robaire B, Plante I. Gestational and Lactational Exposure to an Environmentally Relevant Mixture of Brominated Flame Retardants Downregulates Junctional Proteins, Thyroid Hormone Receptor α1 Expression, and the Proliferation-Apoptosis Balance in Mammary Glands Post Puberty. Toxicol Sci 2019; 171:13-31. [PMID: 31241157 PMCID: PMC6735962 DOI: 10.1093/toxsci/kfz147] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/11/2019] [Accepted: 06/11/2019] [Indexed: 12/21/2022] Open
Abstract
Mammary gland development requires hormonal regulation during puberty, pregnancy, and lactation. Brominated flame retardants (BFRs) are endocrine disruptors; they are added to consumer products to satisfy flammability standards. Previously, we showed that gestational and lactational exposure to an environmentally relevant mixture of BFRs disrupts proteins of the adherens junctions in rat dam mammary glands at weaning. Here, we hypothesize that perinatal exposure to the same BFR mixture also disrupts junctional proteins and signaling pathways controlling mammary gland development in pups. Dams were exposed through diet to a BFR mixture based on the substances in house dust; doses of the mixture used were 0, 0.06, 20, or 60 mg/kg/day. Dams were exposed continuously beginning prior to mating until pups' weaning; female offspring were euthanized on postnatal day (PND) 21, 46, and 208. The lowest dose of BFRs significantly downregulated adherens junction proteins, E-cadherin, and β-catenin, and the gap junction protein p-Cx43, as well as thyroid hormone receptor alpha 1 protein at PND 46. No effects were observed on estrogen or progesterone receptors. The low dose also resulted in a decrease in cleaved caspase-3, a downward trend in PARP levels, proteins involved in apoptosis, and an upward trend in proliferating cell nuclear antigen, a marker of proliferation. No effects were observed on ductal elongation or on the numbers of terminal end buds. Together, our results indicate that gestational and lactational exposure to an environmentally relevant mixture of BFRs disrupts cell-cell interactions, thyroid hormone homeostasis and the proliferation-apoptosis balance at PND 46, a critical stage for mammary gland development.
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Affiliation(s)
| | - Mélanie Lavoie
- INRS, Centre Armand-Frappier Santé Bioscience, Laval, Quebec, Canada
| | - Elham Dianati
- INRS, Centre Armand-Frappier Santé Bioscience, Laval, Quebec, Canada
| | - Mike G Wade
- Health Canada, Environmental Health Science and Research Bureau, Ottawa, Ontario, Canada
| | | | - Bernard Robaire
- Department of Pharmacology & Therapeutics
- Department of Obstetrics & Gynecology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Isabelle Plante
- INRS, Centre Armand-Frappier Santé Bioscience, Laval, Quebec, Canada
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Cyr DG, Dufresne J, Gregory M. Cellular junctions in the epididymis, a critical parameter for understanding male reproductive toxicology. Reprod Toxicol 2018; 81:207-219. [PMID: 30130578 DOI: 10.1016/j.reprotox.2018.08.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/14/2018] [Accepted: 08/16/2018] [Indexed: 12/28/2022]
Abstract
Epididymal sperm maturation is a critical aspect of male reproduction in which sperm acquire motility and the ability to fertilize an ovum. Sperm maturation is dependent on the creation of a specific environment that changes along the epididymis and which enables the maturation process. The blood-epididymis barrier creates a unique luminal micro-environment, different from blood, by limiting paracellular transport and forcing receptor-mediated transport of macromolecules across the epididymal epithelium. Direct cellular communication between cells allows coordinated function of the epithelium. A limited number of studies have directly examined the effects of toxicants on junctional proteins and barrier function in the epididymis. Effects on the integrity of the blood-epididymis barrier have resulted in decreased fertility and, in some cases, the development of sperm granulomas. Studies have shown that in addition to tight junctions, proteins implicated in the maintenance of adherens junctions and gap junctions alter epididymal functions. This review will provide an overview of the types and roles of cellular junctions in the epididymis, and how these are targeted by different toxicants.
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Affiliation(s)
- Daniel G Cyr
- Laboratory for Reproductive Toxicology, INRS-Institut Armand-Frappier, Université du Québec, 531 boul. des Prairies, Laval, Québec, H7V 1B7, Canada.
| | - Julie Dufresne
- Laboratory for Reproductive Toxicology, INRS-Institut Armand-Frappier, Université du Québec, 531 boul. des Prairies, Laval, Québec, H7V 1B7, Canada
| | - Mary Gregory
- Laboratory for Reproductive Toxicology, INRS-Institut Armand-Frappier, Université du Québec, 531 boul. des Prairies, Laval, Québec, H7V 1B7, Canada
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Kibschull M, Gellhaus A, Carette D, Segretain D, Pointis G, Gilleron J. Physiological roles of connexins and pannexins in reproductive organs. Cell Mol Life Sci 2015; 72:2879-98. [PMID: 26100514 PMCID: PMC11114083 DOI: 10.1007/s00018-015-1965-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 06/11/2015] [Indexed: 12/15/2022]
Abstract
Reproductive organs are complex and well-structured tissues essential to perpetuate the species. In mammals, the male and female reproductive organs vary on their organization, morphology and function. Connectivity between cells in such tissues plays pivotal roles in organogenesis and tissue functions through the regulation of cellular proliferation, migration, differentiation and apoptosis. Connexins and pannexins can be seen as major regulators of these physiological processes. In the present review, we assembled several lines of evidence demonstrating that these two families of proteins are essential for male and female reproduction.
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Affiliation(s)
- Mark Kibschull
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 25 Orde Street, Toronto, M5T 3H7 Canada
| | - Alexandra Gellhaus
- Department of Gynecology and Obstetrics, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
| | - Diane Carette
- UMR S1147, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
- University of Versailles, 78035 Saint Quentin, France
- INSERM U 1065, University of Nice Sophia-Antipolis, 151 Route Saint-Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex 3, France
| | - Dominique Segretain
- UMR S1147, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
- University of Versailles, 78035 Saint Quentin, France
| | - Georges Pointis
- INSERM U 1065, University of Nice Sophia-Antipolis, 151 Route Saint-Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex 3, France
| | - Jerome Gilleron
- INSERM U 1065, University of Nice Sophia-Antipolis, 151 Route Saint-Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex 3, France
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Firestone GL, Kapadia BJ. Minireview: regulation of gap junction dynamics by nuclear hormone receptors and their ligands. Mol Endocrinol 2012; 26:1798-807. [PMID: 22935924 DOI: 10.1210/me.2012-1065] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Gap junctions are plasma membrane channels comprising connexin proteins that mediate intercellular permeability and communication. The presence, composition, and function of gap junctions can be regulated by diverse sets of physiological signals. Evidence from many hormone-responsive tissues has shown that connexin expression, modification, stability, and localization can be targeted by nuclear hormone receptors and their ligands through both transcriptional and nontranscriptional mechanisms. The focus of this review is to discuss molecular, cellular, and physiological studies that directly link receptor- and ligand-triggered signaling pathways to the regulation of gap junction dynamics.
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Affiliation(s)
- Gary L Firestone
- Department of Molecular and Cell Biology, 591 LSA, The University of California at Berkeley, Berkeley, California 94720-3200, USA.
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Oyamada M, Takebe K, Oyamada Y. Regulation of connexin expression by transcription factors and epigenetic mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:118-33. [PMID: 22244842 DOI: 10.1016/j.bbamem.2011.12.031] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 12/17/2011] [Accepted: 12/27/2011] [Indexed: 01/24/2023]
Abstract
Gap junctions are specialized cell-cell junctions that directly link the cytoplasm of neighboring cells. They mediate the direct transfer of metabolites and ions from one cell to another. Discoveries of human genetic disorders due to mutations in gap junction protein (connexin [Cx]) genes and experimental data on connexin knockout mice provide direct evidence that gap junctional intercellular communication is essential for tissue functions and organ development, and that its dysfunction causes diseases. Connexin-related signaling also involves extracellular signaling (hemichannels) and non-channel intracellular signaling. Thus far, 21 human genes and 20 mouse genes for connexins have been identified. Each connexin shows tissue- or cell-type-specific expression, and most organs and many cell types express more than one connexin. Connexin expression can be regulated at many of the steps in the pathway from DNA to RNA to protein. In recent years, it has become clear that epigenetic processes are also essentially involved in connexin gene expression. In this review, we summarize recent knowledge on regulation of connexin expression by transcription factors and epigenetic mechanisms including histone modifications, DNA methylation, and microRNA. This article is part of a Special Issue entitled: The communicating junctions, roles and dysfunctions.
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Affiliation(s)
- Masahito Oyamada
- Department of Food Science and Human Nutrition, Fuji Women's University, Ishikarishi, Japan.
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Cyr DG. Connexins and pannexins: Coordinating cellular communication in the testis and epididymis. SPERMATOGENESIS 2011; 1:325-338. [PMID: 22332116 DOI: 10.4161/spmg.1.4.18948] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 10/21/2011] [Accepted: 11/07/2011] [Indexed: 12/15/2022]
Abstract
Gap junctions and connexins are critical for coordinating cellular functions in complex epithelia. In recent years there has been increased interest in understanding the regulation and function of gap junctions in both the testis and epididymis. Studies in transgenic mice in which connexin 43 (Cx43) is mutated or is knocked down only in Sertoli cells have demonstrated the essential role of Cx43 in spermatogenesis and differentiation of Sertoli cells. In the epididymis developmental studies have shown a role for numerous connexins in the differentiation of epithelial cells and communication between the basal cells and both principal and clear cells. In both tissues several factors, such thyroid hormones and androgens, are important in regulating expression and function of connexins. Pannexins, which form cellular channels but are structurally similar to gap junction proteins, have been identified in both testis and epididymis and, in the epididymis, are regulated by androgens. The objective of this review is to summarize the advances that have been made on the role and regulation of connexins and pannexins in the testis and epididymis and their implication in spermatogenesis and sperm maturation.
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Affiliation(s)
- Daniel G Cyr
- INRS-Institut Armand Frappier; University of Quebec; Laval, QC Canada
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