1
|
Melo LH, Melo RMC, Luz RK, Bazzoli N, Rizzo E. Expression of Vasa, Nanos2 and Sox9 during initial testicular development in Nile tilapia (Oreochromis niloticus) submitted to sex reversal. Reprod Fertil Dev 2020; 31:1637-1646. [PMID: 31097079 DOI: 10.1071/rd18488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 04/28/2019] [Indexed: 11/23/2022] Open
Abstract
Sexual differentiation and early gonadal development are critical events in vertebrate reproduction. In this study, the initial testis development and expression of the Vasa, Nanos2 and Sox9 proteins were examined in Nile tilapia Oreochromis niloticus submitted to induced sex reversal. To that end, 150O. niloticus larvae at 5 days post-hatching (dph) were kept in nurseries with no hormonal addition (control group) and 150 larvae were kept with feed containing 17α-methyltestosterone to induce male sex reversal (treated group). Morphological sexual differentiation of Nile tilapia occurred between 21 and 25 dph and sex reversal resulted in 94% males, whereas the control group presented 53% males. During sexual differentiation, gonocytes (Gon) were the predominant germ cells, which decreased and disappeared after that stage in both groups. Undifferentiated spermatogonia (Aund) were identified at 21 dph in the control group and at 23 dph in the treated group. Differentiated spermatogonia (Adiff) were found at 23 dph in both groups. Vasa and Nanos2 occurred in Gon, Aund and Adiff and there were no significant differences between groups. Vasa-labelled Adiff increased at 50 dph in both groups and Nanos2 presented a high proportion of labelled germ cells during sampling. Sertoli cells expressed Sox9 throughout the experiment and its expression was significantly greater during sexual differentiation in the control group. The results indicate that hormonal treatment did not alter initial testis development and expression of Vasa and Nanos2 in Nile tilapia, although lower expression of Sox9 and a delay in sexual differentiation was detected in the treated group.
Collapse
Affiliation(s)
- Luis H Melo
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, UFMG, Av. Antônio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Rafael M C Melo
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, UFMG, Av. Antônio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Ronald K Luz
- Laboratório de Aquacultura, Escola de Veterinária, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, 31270-901 Belo Horizonte, MG, Brazil
| | - Nilo Bazzoli
- Programa de Pós-Graduação em Biologia de Vertebrados, Pontifícia Universidade Católica de Minas Gerais, PUC Minas, Av. Dom José Gaspar 500, 30535-610 Belo Horizonte, Minas Gerais, Brazil
| | - Elizete Rizzo
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, UFMG, Av. Antônio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais, Brazil; and Corresponding author.
| |
Collapse
|
2
|
Lanni S, Pearson CE. Molecular genetics of congenital myotonic dystrophy. Neurobiol Dis 2019; 132:104533. [PMID: 31326502 DOI: 10.1016/j.nbd.2019.104533] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 06/29/2019] [Accepted: 07/11/2019] [Indexed: 12/26/2022] Open
Abstract
Myotonic Dystrophy type 1 (DM1) is a neuromuscular disease showing strong genetic anticipation, and is caused by the expansion of a CTG repeat tract in the 3'-UTR of the DMPK gene. Congenital Myotonic Dystrophy (CDM1) represents the most severe form of the disease, with prenatal onset, symptoms distinct from adult onset DM1, and a high rate of perinatal mortality. CDM1 is usually associated with very large CTG expansions, but this correlation is not absolute and cannot explain the distinct clinical features and the strong bias for maternal transmission. This review focuses upon the molecular and epigenetic factors that modulate disease severity and might be responsible for CDM1. Changes in the epigenetic status of the DM1 locus and in gene expression have recently been observed. Increasing evidence supports a role of a CTCF binding motif as a cis-element, upstream of the DMPK CTG tract, whereby CpG methylation of this site regulates the interaction of the insulator protein CTCF as a modulating trans-factor responsible for the inheritance and expression of CDM1.
Collapse
Affiliation(s)
- Stella Lanni
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto M5G 0A4, Ontario, Canada
| | - Christopher E Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto M5G 0A4, Ontario, Canada; University of Toronto, Program of Molecular Genetics, Canada.
| |
Collapse
|
3
|
Barbé L, Lanni S, López-Castel A, Franck S, Spits C, Keymolen K, Seneca S, Tomé S, Miron I, Letourneau J, Liang M, Choufani S, Weksberg R, Wilson MD, Sedlacek Z, Gagnon C, Musova Z, Chitayat D, Shannon P, Mathieu J, Sermon K, Pearson CE. CpG Methylation, a Parent-of-Origin Effect for Maternal-Biased Transmission of Congenital Myotonic Dystrophy. Am J Hum Genet 2017; 100:488-505. [PMID: 28257691 PMCID: PMC5339342 DOI: 10.1016/j.ajhg.2017.01.033] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 01/26/2017] [Indexed: 12/13/2022] Open
Abstract
CTG repeat expansions in DMPK cause myotonic dystrophy (DM1) with a continuum of severity and ages of onset. Congenital DM1 (CDM1), the most severe form, presents distinct clinical features, large expansions, and almost exclusive maternal transmission. The correlation between CDM1 and expansion size is not absolute, suggesting contributions of other factors. We determined CpG methylation flanking the CTG repeat in 79 blood samples from 20 CDM1-affected individuals; 21, 27, and 11 individuals with DM1 but not CDM1 (henceforth non-CDM1) with maternal, paternal, and unknown inheritance; and collections of maternally and paternally derived chorionic villus samples (7 CVSs) and human embryonic stem cells (4 hESCs). All but two CDM1-affected individuals showed high levels of methylation upstream and downstream of the repeat, greater than non-CDM1 individuals (p = 7.04958 × 10−12). Most non-CDM1 individuals were devoid of methylation, where one in six showed downstream methylation. Only two non-CDM1 individuals showed upstream methylation, and these were maternally derived childhood onset, suggesting a continuum of methylation with age of onset. Only maternally derived hESCs and CVSs showed upstream methylation. In contrast, paternally derived samples (27 blood samples, 3 CVSs, and 2 hESCs) never showed upstream methylation. CTG tract length did not strictly correlate with CDM1 or methylation. Thus, methylation patterns flanking the CTG repeat are stronger indicators of CDM1 than repeat size. Spermatogonia with upstream methylation may not survive due to methylation-induced reduced expression of the adjacent SIX5, thereby protecting DM1-affected fathers from having CDM1-affected children. Thus, DMPK methylation may account for the maternal bias for CDM1 transmission, larger maternal CTG expansions, age of onset, and clinical continuum, and may serve as a diagnostic indicator.
Collapse
|
4
|
Li C, Guo S, Zhang M, Gao J, Guo Y. DNA methylation and histone modification patterns during the late embryonic and early postnatal development of chickens. Poult Sci 2015; 94:706-21. [PMID: 25691759 DOI: 10.3382/ps/pev016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Early mammalian embryonic cells have been proven to be essential for embryonic development and the health of neonates. A series of epigenetic reprogramming events, including DNA methylation and histone modifications, occur during early embryonic development. However, epigenetic marks in late embryos and neonates are not well understood, especially in avian species. To investigate the epigenetic patterns of developing embryos and posthatched chicks, embryos at embryonic day 5 (E5), E8, E11, E14, E17, and E20 and newly hatched chicks on day of life 1 (D1), D7, D14, D21 were collected. The levels of global DNA methylation and histone H3 at lysine 9 residue (H3K9) modifications were measured in samples of liver, jejunum, and breast skeletal muscles by Western blotting and immunofluorescence staining. According to our data, decreased levels of proliferating cell nuclear antigen expression were found in the liver and a V-shaped pattern of proliferating cell nuclear antigen expression was found in the jejunum. The level of proliferating cell nuclear antigen in muscle was relatively stable. Caspase 3 expression gradually decreased over time in liver, was stable in the jejunum, and increased in muscle. Levels of DNA methylation and H3K9 acetylation decreased in liver over time, while the pattern was N-shaped in jejunal tissue and W-shaped in pectoral muscles, and these changes were accompanied by dynamic changes of DNA methyltransferases, histone acetyltransferases 1, and histone deacetylase 2. Moreover, dimethylation, trimethylation, and acetylation of H3K9 were expressed in a time- and tissue-dependent manner. After birth, epigenetic marks were relatively stable and found at lower levels. These results indicate that spatiotemporal specific epigenetic alterations could be critical for the late development of chick embryos and neonates.
Collapse
Affiliation(s)
- Changwu Li
- State Key Laboratory of Animal Nutrition, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Science, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, P. R. China
| | - Shuangshuang Guo
- State Key Laboratory of Animal Nutrition, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Science, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, P. R. China
| | - Ming Zhang
- State Key Laboratory of Animal Nutrition, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Science, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, P. R. China
| | - Jing Gao
- State Key Laboratory of Animal Nutrition, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Science, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, P. R. China
| | - Yuming Guo
- State Key Laboratory of Animal Nutrition, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Science, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, P. R. China
| |
Collapse
|
5
|
F0 maternal BPA exposure induced glucose intolerance of F2 generation through DNA methylation change in Gck. Toxicol Lett 2014; 228:192-9. [DOI: 10.1016/j.toxlet.2014.04.012] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 04/14/2014] [Accepted: 04/17/2014] [Indexed: 01/03/2023]
|
6
|
Abstract
Infertility is a medical condition with an increasing impact in Western societies with causes linked to toxins, genetics, and aging (primarily delay of motherhood). Within the different pathologies that can lead to infertility, poor quality or reduced quantity of gametes plays an important role. Gamete donation and therefore demand on donated sperm and eggs in fertility clinics is increasing. It is hoped that a better understanding of the conditions related to poor gamete quality may allow scientists to design rational treatments. However, to date, relatively little is known about human germ cell development in large part due to the inaccessibility of human development to molecular genetic analysis. It is hoped that pluripotent human embryonic stem cells and induced pluripotent stem cells may provide an accessible in vitro model to study germline development; these cells are able to differentiate to cells of all three primary embryonic germ layers, as well as to germ cells in vitro. We review the state of the art in germline differentiation from pluripotent stem cells.
Collapse
Affiliation(s)
- Jose V Medrano
- Fundación Instituto Valenciano de Infertilidad, Parc Cientific Universitat de Valencia, Paterna, Valencia, Spain.
| | | | | |
Collapse
|
7
|
Bowles J, Koopman P. Precious Cargo: Regulation of Sex-Specific Germ Cell Development in Mice. Sex Dev 2013; 7:46-60. [DOI: 10.1159/000342072] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
|
8
|
Ciccarone F, Klinger FG, Catizone A, Calabrese R, Zampieri M, Bacalini MG, De Felici M, Caiafa P. Poly(ADP-ribosyl)ation acts in the DNA demethylation of mouse primordial germ cells also with DNA damage-independent roles. PLoS One 2012; 7:e46927. [PMID: 23071665 PMCID: PMC3465317 DOI: 10.1371/journal.pone.0046927] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 09/06/2012] [Indexed: 01/15/2023] Open
Abstract
Poly(ADP-ribosyl)ation regulates chromatin structure and transcription driving epigenetic events. In particular, Parp1 is able to directly influence DNA methylation patterns controlling transcription and activity of Dnmt1. Here, we show that ADP-ribose polymer levels and Parp1 expression are noticeably high in mouse primordial germ cells (PGCs) when the bulk of DNA demethylation occurs during germline epigenetic reprogramming in the embryo. Notably, Parp1 activity is stimulated in PGCs even before its participation in the DNA damage response associated with active DNA demethylation. We demonstrate that PARP inhibition impairs both genome-wide and locus-specific DNA methylation erasure in PGCs. Moreover, we evidence that impairment of PARP activity causes a significant reduction of expression of the gene coding for Tet1 hydroxylases involved in active DNA demethylation. Taken together these results demonstrate new and adjuvant roles of poly(ADP-ribosyl)ation during germline DNA demethylation and suggest its possible more general involvement in genome reprogramming.
Collapse
Affiliation(s)
- Fabio Ciccarone
- Department of Cellular Biotechnologies and Hematology, Sapienza University of Rome, Rome, Italy
- Pasteur Institute-Fondazione Cenci Bolognetti, Rome, Italy
| | | | - Angela Catizone
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy
| | - Roberta Calabrese
- Department of Cellular Biotechnologies and Hematology, Sapienza University of Rome, Rome, Italy
- Pasteur Institute-Fondazione Cenci Bolognetti, Rome, Italy
| | - Michele Zampieri
- Department of Cellular Biotechnologies and Hematology, Sapienza University of Rome, Rome, Italy
- Pasteur Institute-Fondazione Cenci Bolognetti, Rome, Italy
| | - Maria Giulia Bacalini
- Department of Cellular Biotechnologies and Hematology, Sapienza University of Rome, Rome, Italy
- Pasteur Institute-Fondazione Cenci Bolognetti, Rome, Italy
| | - Massimo De Felici
- Department of Public Health and Cell Biology, University of Rome Tor Vergata, Rome, Italy
| | - Paola Caiafa
- Department of Cellular Biotechnologies and Hematology, Sapienza University of Rome, Rome, Italy
- Pasteur Institute-Fondazione Cenci Bolognetti, Rome, Italy
| |
Collapse
|
9
|
Zhang LJ, Pan B, Chen B, Zhang XF, Liang GJ, Feng YN, Wang LQ, Ma JM, Li L, Shen W. Expression and epigenetic dynamics of transcription regulator Lhx8 during mouse oogenesis. Gene 2012; 506:1-9. [PMID: 22796561 DOI: 10.1016/j.gene.2012.06.093] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 06/23/2012] [Accepted: 06/28/2012] [Indexed: 12/22/2022]
Abstract
The spatial and temporal specific activation and inhibition of numerous genes are required for successful oogenesis which is precisely regulated by germ cell-related transcription factors, and appropriate epigenetic modifications, including DNA methylation, histone modification and other mechanisms that closely regulate the functional exertion of these transcription factors. In this study, we characterized the correlation between the expression and epigenetic dynamics of Lhx8, a germ cell specific transcription factor during mouse oogenesis. Immunohistochemistry, quantitative PCR and western blots were performed to localize and quantify the expressional characteristics of Lhx8 in oocytes of 13.5 dpc (day post coitum), 17.5 dpc, 0 dpp (day post partum), 3 dpp, 7 dpp and 14 dpp. The results showed that LHX8 protein was located in the nucleus of oocytes, and increasingly expressed during primordial follicle activation. Sequencing of bisulfite-converted genomic DNAs revealed that the methylation dynamics of Lhx8-3' was highly changeable but almost no change occurred in Lhx8-5'. ChIP-QPCR analysis showed that histone H3 acetylation of Lhx8 was also increased during primordial follicle assembly and activation. In conclusion, Lhx8 expression is related with the activation of primordial follicles, which is highly correlated with the demethylation of Lhx8-3' untranslated region and the high acetylation of histone H3.
Collapse
Affiliation(s)
- Lian-Jun Zhang
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao Agricultural University, Qingdao, 266109, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Encinas G, Zogbi C, Stumpp T. Detection of Four Germ Cell Markers in Rats during Testis Morphogenesis: Differences and Similarities with Mice. Cells Tissues Organs 2012; 195:443-55. [DOI: 10.1159/000329245] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2011] [Indexed: 11/19/2022] Open
|
11
|
De Felici M. Nuclear reprogramming in mouse primordial germ cells: epigenetic contribution. Stem Cells Int 2011; 2011:425863. [PMID: 21969835 PMCID: PMC3182379 DOI: 10.4061/2011/425863] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 07/11/2011] [Indexed: 12/17/2022] Open
Abstract
The unique capability of germ cells to give rise to a new organism, allowing the transmission of primary genetic information from generation to generation, depends on their epigenetic reprogramming ability and underlying genomic totipotency. Recent studies have shown that genome-wide epigenetic modifications, referred to as “epigenetic reprogramming”, occur during the development of the gamete precursors termed primordial germ cells (PGCs) in the embryo. This reprogramming is likely to be critical for the germ line development itself and necessary to erase the parental imprinting and setting the base for totipotency intrinsic to this cell lineage. The status of genome acquired during reprogramming and the associated expression of key pluripotency genes render PGCs susceptible to transform into pluripotent stem cells. This may occur in vivo under still undefined condition, and it is likely at the origin of the formation of germ cell tumors. The phenomenon appears to be reproduced under partly defined in vitro culture conditions, when PGCs are transformed into embryonic germ (EG) cells. In the present paper, I will try to summarize the contribution that epigenetic modifications give to nuclear reprogramming in mouse PGCs.
Collapse
Affiliation(s)
- Massimo De Felici
- Section of Histology and Embryology, Department of Public Health and Cell Biology, University of Rome "Tor Vergata," 00173 Rome, Italy
| |
Collapse
|
12
|
Hyldig SMW, Ostrup O, Vejlsted M, Thomsen PD. Changes of DNA Methylation Level and Spatial Arrangement of Primordial Germ Cells in Embryonic Day 15 to Embryonic Day 28 Pig Embryos1. Biol Reprod 2011; 84:1087-93. [DOI: 10.1095/biolreprod.110.086082] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
|
13
|
Rolland AD, Lehmann KP, Johnson KJ, Gaido KW, Koopman P. Uncovering gene regulatory networks during mouse fetal germ cell development. Biol Reprod 2010; 84:790-800. [PMID: 21148109 DOI: 10.1095/biolreprod.110.088443] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The commitment of germ cells to either oogenesis or spermatogenesis occurs during fetal gonad development: germ cells enter meiosis or mitotic arrest, depending on whether they reside within an ovary or a testis, respectively. Despite the critical importance of this step for sexual reproduction, gene networks underlying germ cell development have remained only partially understood. Taking advantage of the W(v) mouse model, in which gonads lack germ cells, we conducted a microarray study to identify genes expressed in fetal germ cells. In addition to distinguishing genes expressed by germ cells from those expressed by somatic cells within the developing gonads, we were able to highlight specific groups of genes expressed only in female or male germ cells. Our results provide an important resource for deciphering the molecular pathways driving proper germ cell development and sex determination and will improve our understanding of the etiology of human germ cell tumors that arise from dysregulation of germ cell differentiation.
Collapse
Affiliation(s)
- Antoine D Rolland
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | | | | | | | | |
Collapse
|
14
|
Abstract
Primordial germ cells (PGCs) are embryonic progenitors for the gametes. In the gastrulating mouse embryo, a small group of cells begin expressing a unique set of genes and so commit to the germline. Over the next 3-5 days, these PGCs migrate anteriorly and increase rapidly in number via mitotic division before colonizing the newly formed gonads. PGCs then express a different set of unique genes, their inherited epigenetic imprint is erased and an individual methylation imprint is established, and for female PGCs, the silent X chromosome is reactivated. At this point, germ cells (GCs) commit to either a female or male sexual lineage, denoted by meiosis entry and mitotic arrest, respectively. This developmental program is determined by cues emanating from the somatic environment.
Collapse
Affiliation(s)
- Katherine A Ewen
- Division of Molecular Genetics and Development, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | | |
Collapse
|
15
|
Bowles J, Koopman P. Sex determination in mammalian germ cells: extrinsic versus intrinsic factors. Reproduction 2010; 139:943-58. [DOI: 10.1530/rep-10-0075] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mammalian germ cells do not determine their sexual fate based on their XX or XY chromosomal constitution. Instead, sexual fate is dependent on the gonadal environment in which they develop. In a fetal testis, germ cells commit to the spermatogenic programme of development during fetal life, although they do not enter meiosis until puberty. In a fetal ovary, germ cells commit to oogenesis by entering prophase of meiosis I. Although it was believed previously that germ cells are pre-programmed to enter meiosis unless they are actively prevented from doing so, recent results indicate that meiosis is triggered by a signaling molecule, retinoic acid (RA). Meiosis is avoided in the fetal testis because a male-specifically expressed enzyme actively degrades RA during the critical time period. Additional extrinsic factors are likely to influence sexual fate of the germ cells, and in particular, we postulate that an additional male-specific fate-determining factor or factors is involved. The full complement of intrinsic factors that underlie the competence of gonadal germ cells to respond to RA and other extrinsic factors is yet to be defined.
Collapse
|
16
|
Cinquin O. Purpose and regulation of stem cells: a systems-biology view from the Caenorhabditis elegans germ line. J Pathol 2009; 217:186-98. [PMID: 19065622 PMCID: PMC2929242 DOI: 10.1002/path.2481] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Stem cells are expected to play a key role in the development and maintenance of organisms, and hold great therapeutic promises. However, a number of questions must be answered to achieve an understanding of stem cells and put them to use. Here I review some of these questions, and how they relate to the model system provided by the Caenorhabditis elegans germ line, which is exceptional in its thorough genetic characterization and experimental accessibility under in vivo conditions. A fundamental question is how to define a stem cell; different definitions can be adopted that capture different features of interest. In the C. elegans germ line, stem cells can be defined by cell lineage or by cell commitment ('commitment' must itself be carefully defined). These definitions are associated with two other important questions about stem cells: their functions (which must be addressed following a systems approach, based on an evolutionary perspective) and their regulation. I review possible functions and their evolutionary groundings, including genome maintenance and powerful regulation of cell proliferation and differentiation, and possible regulatory mechanisms, including asymmetrical division and control of transit amplification by a developmental timer. I draw parallels between Drosophila and C. elegans germline stem cells; such parallels raise intriguing questions about Drosophila stem cells. I conclude by showing that the C. elegans germ line bears similarities with a number of other stem cell systems, which underscores its relevance to the understanding of stem cells.
Collapse
Affiliation(s)
- Olivier Cinquin
- Howard Hughes Medical Institute and Department of Biochemistry, University of Wisconsin-Madison, WI 53706, USA.
| |
Collapse
|
17
|
Abstract
Germ cells constitute a highly specialized cell population that is indispensable for the continuation and evolution of the species. Recently, several research groups have shown that these unique cells can be produced in vitro from pluripotent stem cells. Furthermore, live births of offspring using induced germ cells have been reported in one study. These results suggest that it may be possible to investigate germ cell development ex vivo and to establish novel reproductive technologies. To this end, it is critical to assess if gamete induction processes in vitro faithfully recapitulate normal germ cell development in vivo. Here, this issue is discussed with a focus on the germ line specification and the sex-specific development of pre- and postnatal germ cells. The aim of this paper is to concisely summarize the past progress and to present some future issues for the investigation into in vitro gamete production from pluripotent stem cells.
Collapse
Affiliation(s)
- Makoto C Nagano
- Department of Obstetrics and Gynecology and Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada H3A 1A1.
| |
Collapse
|
18
|
Maatouk DM, Kellam LD, Mann MRW, Lei H, Li E, Bartolomei MS, Resnick JL. DNA methylation is a primary mechanism for silencing postmigratory primordial germ cell genes in both germ cell and somatic cell lineages. Development 2006; 133:3411-8. [PMID: 16887828 DOI: 10.1242/dev.02500] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
DNA methylation is necessary for the silencing of endogenous retrotransposons and the maintenance of monoallelic gene expression at imprinted loci and on the X chromosome. Dynamic changes in DNA methylation occur during the initial stages of primordial germ cell development; however, all consequences of this epigenetic reprogramming are not understood. DNA demethylation in postmigratory primordial germ cells coincides with erasure of genomic imprints and reactivation of the inactive X chromosome, as well as ongoing germ cell differentiation events. To investigate a possible role for DNA methylation changes in germ cell differentiation, we have studied several marker genes that initiate expression at this time. Here, we show that the postmigratory germ cell-specific genes Mvh, Dazl and Scp3 are demethylated in germ cells, but not in somatic cells. Premature loss of genomic methylation in Dnmt1 mutant embryos leads to early expression of these genes as well as GCNA1, a widely used germ cell marker. In addition, GCNA1 is ectopically expressed by somatic cells in Dnmt1 mutants. These results provide in vivo evidence that postmigratory germ cell-specific genes are silenced by DNA methylation in both premigratory germ cells and somatic cells. This is the first example of ectopic gene activation in Dnmt1 mutant mice and suggests that dynamic changes in DNA methylation regulate tissue-specific gene expression of a set of primordial germ cell-specific genes.
Collapse
Affiliation(s)
- Danielle M Maatouk
- Department of Molecular Genetics and Microbiology, PO Box 100266, University of Florida, Gainesville, FL 32610-0266, USA
| | | | | | | | | | | | | |
Collapse
|
19
|
Plachot C, Lelièvre SA. DNA methylation control of tissue polarity and cellular differentiation in the mammary epithelium. Exp Cell Res 2004; 298:122-32. [PMID: 15242767 DOI: 10.1016/j.yexcr.2004.04.024] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2004] [Revised: 04/14/2004] [Indexed: 10/26/2022]
Abstract
Alterations in gene expression accompany cell-type-specific differentiation. In complex systems where functional differentiation depends on the organization of specific cell types into highly specialized structures (tissue morphogenesis), it is not known how epigenetic mechanisms that control gene expression influence this stepwise differentiation process. We have investigated the effect of DNA methylation, a major epigenetic pathway of gene silencing, on the regulation of mammary acinar differentiation. Our in vitro model of differentiation encompasses human mammary epithelial cells that form polarized and hollow tissue structures (acini) when cultured in the presence of basement membrane components. We found that acinar morphogenesis was accompanied with chromatin remodeling, as shown by alterations in histone 4 acetylation, heterochromatin 1 protein, and histone 3 methylated on lysine 9, and with an increase in expression of MeCP2, a mediator of DNA-methylation-induced gene silencing. DNA hypomethylation induced by treatment with 5-aza-2' deoxycytidine during acinar differentiation essentially prevented the formation of apical tissue polarity. This treatment also induced the expression of CK19, a marker of cells that are in a transitional differentiation stage. These results suggest that DNA methylation is a mechanism by which mammary epithelial differentiation is coordinated both at the tissue and cellular levels.
Collapse
Affiliation(s)
- Cedric Plachot
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907-2026, USA
| | | |
Collapse
|
20
|
Marchal R, Chicheportiche A, Dutrillaux B, Bernardino-Sgherri J. DNA methylation in mouse gametogenesis. Cytogenet Genome Res 2004; 105:316-24. [PMID: 15237219 DOI: 10.1159/000078204] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Indexed: 11/19/2022] Open
Abstract
DNA methylation is involved in many biological processes and is particularly important for both development and germ cell differentiation. Several waves of demethylation and de novo methylation occur during both male and female germ line development. This has been found at both the gene and all genome levels, but there is no demonstrated correlation between them. During the postnatal germ line development of spermatogenesis, we found very complex and drastic DNA methylation changes that we could correlate with chromatin structure changes. Thus, detailed studies focused on localization and expression pattern of the chromatin proteins involved in both DNA methylation, histone tails modification, condensin and cohesin complex formation, should help to gain insights into the mechanisms at the origin of the deep changes occurring during this particular period.
Collapse
Affiliation(s)
- R Marchal
- Laboratoire de radiosensibilité des cellules germinales, Département de Radiobiologie et Radiopathologie, CEA/DSV/SEGG/LRCG Fontenay-aux-roses, France
| | | | | | | |
Collapse
|
21
|
Abstract
CONTEXT The genetic code in the DNA of virtually every somatic cell can produce the entire complement of encoded proteins. Acetylation of histones and methylation of histones and DNA cytosine residues are part of the complex epigenetic regulatory process determining lineage-specific gene expression by altering the local structure of chromatin. After fertilisation, sperm DNA exchanges protamines for histones recruited from oocyte cytoplasm, reconfiguring both parental genomes into an epigenetic state conducive to activating the embryonic developmental programme. The identification of epigenetic reprogramming mechanisms is a major interest, rekindled by the ability of at least some somatic cells to acquire totipotency after somatic-cell nuclear transfer. STARTING POINT Recently, Woo SukHwang and colleagues (Science 2004; 303: 1669-74) derived a human embryonic stem-cell line from embryo therapeutic cloning. Chad Cowan and colleagues (N Engl JMed 2004; 350: 1353-56) produced 17 new lines from embryos supernumerary to infertility treatments. However, increasing evidence from a range of mammals shows a propensity for epigenetic errors with embryo technologies. If paralleled in human embryos, the effect on tumorigenic and differentiation properties of embryonic stem cells needs to be established. WHERE NEXT? Identifying the mechanisms in the oocyte that reprogramme a somatic cell to the embryonic state might allow somatic cells to be reprogrammed ex ovo by in-vitro manipulation of the epigenome. Because the oocyte is designed to reprogramme the sperm genome, which is in a different chromatin state from a somatic cell, perhaps many of the epigenetic errors induced by somatic-cell nuclear transfer could be avoided by a more targeted approach.
Collapse
Affiliation(s)
- Cinzia Allegrucci
- Division of Obstetrics and Gynaecology, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, UK
| | | | | | | |
Collapse
|
22
|
Affiliation(s)
- Anne McLaren
- The Wellcome Trust/Cancer Research UK Institute of Cancer and Developmental Biology, Tennis Court Road, Cambridge CB2 1QR, UK.
| |
Collapse
|