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Cortes LR, Cisternas CD, Forger NG. Does Gender Leave an Epigenetic Imprint on the Brain? Front Neurosci 2019; 13:173. [PMID: 30872999 PMCID: PMC6400866 DOI: 10.3389/fnins.2019.00173] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/13/2019] [Indexed: 01/21/2023] Open
Abstract
The words “sex” and “gender” are often used interchangeably in common usage. In fact, the Merriam-Webster dictionary offers “sex” as the definition of gender. The authors of this review are neuroscientists, and the words “sex” and “gender” mean very different things to us: sex is based on biological factors such as sex chromosomes and gonads, whereas gender has a social component and involves differential expectations or treatment by conspecifics, based on an individual’s perceived sex. While we are accustomed to thinking about “sex” and differences between males and females in epigenetic marks in the brain, we are much less used to thinking about the biological implications of gender. Nonetheless, careful consideration of the field of epigenetics leads us to conclude that gender must also leave an epigenetic imprint on the brain. Indeed, it would be strange if this were not the case, because all environmental influences of any import can epigenetically change the brain. In the following pages, we explain why there is now sufficient evidence to suggest that an epigenetic imprint for gender is a logical conclusion. We define our terms for sex, gender, and epigenetics, and describe research demonstrating sex differences in epigenetic mechanisms in the brain which, to date, is mainly based on work in non-human animals. We then give several examples of how gender, rather than sex, may cause the brain epigenome to differ in males and females, and finally consider the myriad of ways that sex and gender interact to shape gene expression in the brain.
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Affiliation(s)
- Laura R Cortes
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Carla D Cisternas
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Nancy G Forger
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
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Western PS. Epigenomic drugs and the germline: Collateral damage in the home of heritability? Mol Cell Endocrinol 2018; 468:121-133. [PMID: 29471014 DOI: 10.1016/j.mce.2018.02.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 02/16/2018] [Accepted: 02/16/2018] [Indexed: 02/07/2023]
Abstract
The testis and ovary provide specialised environments that nurture germ cells and facilitate their maturation, culminating in the production of mature gametes that can found the following generation. The sperm and egg not only transmit genetic information, but also epigenetic modifications that affect the development and physiology of offspring. Importantly, the epigenetic information contained in mature sperm and oocytes can be influenced by a range of environmental factors, such as diet, chemicals and drugs. An increasing range of studies are revealing how gene-environment interactions are mediated through the germline. Outside the germline, altered epigenetic state is common in a range of diseases, including many cancers. As epigenetic modifications are reversible, pharmaceuticals that directly target epigenetic modifying proteins have been developed and are delivering substantial benefits to patients, particularly in oncology. While providing the most effective patient treatment is clearly the primary concern, some patients will want to conceive children after treatment. However, the impacts of epigenomic drugs on the male and female gametes are poorly understood and whether these drugs will have lasting effects on patients' germline epigenome and subsequent offspring remains largely undetermined. Currently, evidence based clinical guidelines for use of epigenomic drugs in patients of reproductive age are limited in this context. Developing a deeper understanding of the epigenetic mechanisms regulating the germline epigenome and its impact on inherited traits and disease susceptibility is required to determine how specific epigenomic drugs might affect the germline and inheritance. Understanding these potential effects will facilitate the development of informed clinical guidelines appropriate for the use of epigenomic drugs in patients of reproductive age, ultimately improving the safety of these therapies in the clinic.
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Affiliation(s)
- Patrick S Western
- Centre for Reproductive Health, Hudson Institute of Medical Research and Department of Molecular and Translational Science, Monash University, Clayton, Victoria, 3168, Australia.
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Zhao L, Arsenault M, Ng ET, Longmuss E, Chau TCY, Hartwig S, Koopman P. SOX4 regulates gonad morphogenesis and promotes male germ cell differentiation in mice. Dev Biol 2017; 423:46-56. [PMID: 28118982 DOI: 10.1016/j.ydbio.2017.01.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 12/14/2016] [Accepted: 01/09/2017] [Indexed: 01/13/2023]
Abstract
The group C SOX transcription factors SOX4, -11 and -12 play important and mutually overlapping roles in development of a number of organs. Here, we examined the role of SoxC genes during gonadal development in mice. All three genes were expressed in developing gonads of both sexes, predominantly in somatic cells, with Sox4 being most strongly expressed. Sox4 deficiency resulted in elongation of both ovaries and testes, and an increased number of testis cords. While female germ cells entered meiosis normally, male germ cells showed reduced levels of differentiation markers Nanos2 and Dnmt3l and increased levels of pluripotency genes Cripto and Nanog, suggesting that SOX4 may normally act to restrict the pluripotency period of male germ cells and ensure their proper differentiation. Finally, our data reveal that SOX4 (and, to a lesser extent, SOX11 and -12) repressed transcription of the sex-determining gene Sox9 via an upstream testis-specific enhancer core (TESCO) element in fetal gonads, raising the possibility that SOXC proteins may function as transcriptional repressors in a context-dependent manner.
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Affiliation(s)
- Liang Zhao
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Michel Arsenault
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island,550 University Avenue, Charlottetown, PE, Canada C1A 4P3
| | - Ee Ting Ng
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Enya Longmuss
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Tevin Chui-Ying Chau
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sunny Hartwig
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island,550 University Avenue, Charlottetown, PE, Canada C1A 4P3
| | - Peter Koopman
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
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Walker DM, Gore AC. Epigenetic impacts of endocrine disruptors in the brain. Front Neuroendocrinol 2017; 44:1-26. [PMID: 27663243 PMCID: PMC5429819 DOI: 10.1016/j.yfrne.2016.09.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/05/2016] [Accepted: 09/14/2016] [Indexed: 12/12/2022]
Abstract
The acquisition of reproductive competence is organized and activated by steroid hormones acting upon the hypothalamus during critical windows of development. This review describes the potential role of epigenetic processes, particularly DNA methylation, in the regulation of sexual differentiation of the hypothalamus by hormones. We examine disruption of these processes by endocrine-disrupting chemicals (EDCs) in an age-, sex-, and region-specific manner, focusing on how perinatal EDCs act through epigenetic mechanisms to reprogram DNA methylation and sex steroid hormone receptor expression throughout life. These receptors are necessary for brain sexual differentiation and their altered expression may underlie disrupted reproductive physiology and behavior. Finally, we review the literature on histone modifications and non-coding RNA involvement in brain sexual differentiation and their perturbation by EDCs. By putting these data into a sex and developmental context we conclude that perinatal EDC exposure alters the developmental trajectory of reproductive neuroendocrine systems in a sex-specific manner.
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Affiliation(s)
- Deena M Walker
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1065, New York, NY 10029, USA.
| | - Andrea C Gore
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, and The University of Texas at Austin, Austin, TX 78712, USA; Institute for Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA
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Petropoulos S, Panula SP, Schell JP, Lanner F. Single-cell RNA sequencing: revealing human pre-implantation development, pluripotency and germline development. J Intern Med 2016; 280:252-64. [PMID: 27046137 DOI: 10.1111/joim.12493] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Early human development is a dynamic, heterogeneous, complex and multidimensional process. During the first week, the single-cell zygote undergoes eight to nine rounds of cell division generating the multicellular blastocyst, which consists of hundreds of cells forming spatially organized embryonic and extra-embryonic tissues. At the level of transcription, degradation of maternal RNA commences at around the two-cell stage, coinciding with embryonic genome activation. Although numerous efforts have recently focused on delineating this process in humans, many questions still remain as thorough investigation has been limited by ethical issues, scarce availability of human embryos and the presence of minute amounts of DNA and RNA. In vitro cultures of embryonic stem cells provide some insight into early human development, but such studies have been confounded by analysis on a population level failing to appreciate cellular heterogeneity. Recent technical developments in single-cell RNA sequencing have provided a novel and powerful tool to explore the early human embryo in a systematic manner. In this review, we will discuss the advantages and disadvantages of the techniques utilized to specifically investigate human development and consider how the technology has yielded new insights into pre-implantation development, embryonic stem cells and the establishment of the germ line.
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Affiliation(s)
- S Petropoulos
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet and, Division of Obstetrics and Gynecology, Karolinska University Hospital, Stockholm, Sweden.,Ludwig Institute for Cancer Research, Stockholm, Sweden
| | - S P Panula
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet and, Division of Obstetrics and Gynecology, Karolinska University Hospital, Stockholm, Sweden
| | - J P Schell
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet and, Division of Obstetrics and Gynecology, Karolinska University Hospital, Stockholm, Sweden
| | - F Lanner
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet and, Division of Obstetrics and Gynecology, Karolinska University Hospital, Stockholm, Sweden
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Cong W, Liu B, Liu S, Sun M, Liu H, Yang Y, Wang R, Xiao J. Implications of the Wnt5a/CaMKII pathway in retinoic acid-induced myogenic tongue abnormalities of developing mice. Sci Rep 2014; 4:6082. [PMID: 25124193 PMCID: PMC4133706 DOI: 10.1038/srep06082] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 07/24/2014] [Indexed: 01/26/2023] Open
Abstract
Although proper tongue development is relevant to other structures in the craniofacial region, the molecular details of muscle development in tongue remain poorly understood. Here, we report that pregnant mice treated with retinoic acid (+RA) produce embryos with tongue malformation and a cleft palate. Histological analyses revealed that at E14.5, the tongues of +RA fetuses failed to descend and flatten. Ultrastructural analysis showed that at perinatal stage E18.5, the myofilaments failed to form normal structures of sarcomeres, and arranged disorderly in the genioglossus. The proliferation and levels of myogenic determination markers (Myf5 and MyoD) and myosin in the genioglossus were profoundly reduced. Wnt5a and Camk2d expressions were down-regulated, while levels of Tbx1, Ror2, and PKCδ were up-regulated in the tongues of +RA fetuses. In mock- and Wnt5a-transfected C2C12 (Wnt5a-C2C12) cells, Wnt5a overexpression impaired proliferation, and maintained Myf5 at a relative high level after RA treatment. Furthermore, Wnt5a overexpression positively correlated with levels of Camk2d and Ror2 in C2C12 cells after RA exposure. These data support the hypothesis that the Wnt5a/CaMKII pathway is directly involved in RA-induced hypoplasia and disorder of tongue muscles.
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Affiliation(s)
- Wei Cong
- Department of Oral Pathology, College of Stomatology, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Bo Liu
- Department of Oral Pathology, College of Stomatology, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Shuqing Liu
- Department of Biochemistry, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Mingzhong Sun
- Department of Biotechnology, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Han Liu
- Department of Oral Pathology, College of Stomatology, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Yue Yang
- Department of Oral Pathology, College of Stomatology, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Ru Wang
- Department of Stomatology, the First Affiliated Hospital, Dalian Medical University, Dalian, Liaoning, 116011, China
| | - Jing Xiao
- Department of Oral Pathology, College of Stomatology, Dalian Medical University, Dalian, Liaoning, 116044, China
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Sharpe RM, Mitchell RT. The downside of 'inappropriate messaging': new insight into the development of testicular germ cell tumours in young men? J Pathol 2013; 229:497-501. [PMID: 23335366 DOI: 10.1002/path.4167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 12/30/2012] [Accepted: 01/01/2013] [Indexed: 12/19/2022]
Abstract
How invasive testicular germ cell tumours (TGCTs) develop from precursor carcinoma in situ/intratubular germ cell neoplasia unclassified (CIS/IGCNU) cells, and only after puberty, is unknown. In the current issue of The Journal of Pathology, Jørgensen and colleagues have compared the protein expression profile of CIS before and after puberty and in pre-invasive versus invasive TGCT and show that the mitosis-meiosis controller DMRT1 switches off in CIS cells postpubertally and is associated with invasiveness. They also show that CIS cells express a 'confusing' mix of pro- and anti-meiotic proteins; this may predispose CIS cells to accumulate extra chromosomal material which ultimately leads to tumourigenesis.
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Affiliation(s)
- Richard M Sharpe
- MRC Centre for Reproductive Health, The Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK.
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Jørgensen A, Nielsen JE, Almstrup K, Toft BG, Petersen BL, Rajpert-De Meyts E. Dysregulation of the mitosis-meiosis switch in testicular carcinoma in situ. J Pathol 2013; 229:588-98. [PMID: 23303528 DOI: 10.1002/path.4154] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 11/15/2012] [Accepted: 11/27/2012] [Indexed: 12/17/2022]
Abstract
Testicular germ cell tumours (TGCT) of young adults arise from the intratubular precursor, carcinoma in situ (CIS). CIS cells are thought to be developmentally arrested and transformed fetal germ cells that survive through childhood and gain invasive capacity after puberty. Given that germ cell neoplasms arise frequently in undervirilized and dysgenetic gonads and the striking physiological difference between meiotic entry in ovaries (fetal life) versus testes (at puberty), this study aimed to investigate whether errors in regulation of meiosis may be implicated in the pathogenesis of CIS or its invasive progression to TGCT. The main focus was on a key sex differentiation and meiosis regulator, DMRT1, which has also been linked to TGCT risk in recent genetic association studies. Expression patterns of DMRT1 and other meiosis regulators (SCP3, DMC1, STRA8, CYP26B1, NANOS2, NANOS3) were investigated in pre- and post-pubertal CIS samples and TGCT by quantitative RT-PCR and immunohistochemistry. The results demonstrated that meiosis markers and meiosis inhibitors were simultaneously expressed in CIS cells, in both pre- and post-pubertal testis samples. DMRT1 was present in a restricted subset of CIS cells, which was relatively greater in pre-pubertal (27%) compared to adult (2.6%) samples. In contrast to the majority of CIS cells, DMRT1-positive CIS cells in adult testes were not proliferating. DMRT1 and most of the other meiosis regulators were absent or expressed at low levels in invasive TGCT, except in spermatocytic seminoma (not derived from CIS). In conclusion, this study indicates that meiosis signalling is dysregulated in CIS cells and that a key regulator of the mitosis-meiosis switch, DMRT1, is expressed in 'early-stage' CIS cells but is down-regulated with further invasive transformation. Whether this mixed meiosis signalling in CIS cells is caused by insufficient virilization of the fetal somatic niche or a partial post-pubertal maturation remains uncertain and requires further study.
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Affiliation(s)
- Anne Jørgensen
- Department of Growth and Reproduction, Copenhagen University Hospital, Denmark
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