151
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Lensch MW, Daheron L, Schlaeger TM. Pluripotent stem cells and their niches. ACTA ACUST UNITED AC 2006; 2:185-201. [PMID: 17625255 DOI: 10.1007/s12015-006-0047-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 02/04/2023]
Abstract
The ability of stem cells to self-renew and to replace mature cells is fundamental to ontogeny and tissue regeneration. Stem cells of the adult organism can be categorized as mono-, bi-, or multipotent, based on the number of mature cell types to which they can give rise. In contrast, pluripotent stem cells of the early embryo have the ability to form every cell type of the adult body. Permanent lines of pluripotent stem cells have been derived from preimplantation embryos (embryonic stem cells), fetal primordial germ cells (embryonic germ cells), and malignant teratocarcinomas (embryonal carcinoma cells). Cultured pluripotent stem cells can easily be manipulated genetically, and they can be matured into adult-type stem cells and terminally differentiated cell types in vitro, thereby, providing powerful model systems for the study of mammalian embryogenesis and disease processes. In addition, human embryonic stem cell lines hold great promise for the development of novel regenerative therapies. To fully utilize the potential of these cells, we must first understand the mechanisms that control pluripotent stem cell fate and function. In recent decades, the microenvironment or niche has emerged as particularly critical for stem cell regulation. In this article, we review how pluripotent stem cell signal transduction mechanisms and transcription factor circuitries integrate information provided by the microenvironment. In addition, we consider the potential existence and location of adult pluripotent stem cell niches, based on the notion that a revealing feature indicating the presence of stem cells in a given tissue is the occurrence of tumors whose characteristics reflect the normal developmental potential of the cognate stem cells.
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Affiliation(s)
- M William Lensch
- Division of Hematology/Oncology, Children's Hospital Boston, Boston, MA 02115, USA
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152
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Bosman EA, Lawson KA, Debruyn J, Beek L, Francis A, Schoonjans L, Huylebroeck D, Zwijsen A. Smad5 determines murine amnion fate through the control of bone morphogenetic protein expression and signalling levels. Development 2006; 133:3399-409. [PMID: 16887830 DOI: 10.1242/dev.02497] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Smad5 is an intracellular mediator of bone morphogenetic protein (Bmp)signalling. It is essential for primordial germ cell (PGC) development, for the development of the allantois and for amnion closure, as demonstrated by loss of Bmp signalling. By contrast, the appearance of ectopic PGC-like cells and regionalized ectopic vasculogenesis and haematopoiesis in thickened Smad5m1/m1 amnion are amnion defects that have not been associated with loss of Bmp signalling components. We show that defects in amnion and allantois can already be detected at embryonic day (E) 7.5 in Smad5 mutant mice. However, ectopic Oct4-positive (Oct4+)and alkaline phosphatase-positive (AP+) cells appear suddenly in thickened amnion at E8.5, and at a remote distance from the allantois and posterior primitive streak, suggesting a change of fate in situ. These ectopic Oct4+, AP+ cells appear to be Stella negative and hence cannot be called bona fide PGCs. We demonstrate a robust upregulation of Bmp2 and Bmp4 expression, as well as of Erk and Smad activity, in the Smad5 mutant amnion. The ectopic expression of several Bmp target genes in different domains and the regionalized presence of cells of several Bmp-sensitive lineages in the mutant amnion suggest that different levels of Bmp signalling may determine cell fate. Injection of rBMP4 in the exocoelom of wild-type embryos can induce thickening of amnion,mimicking the early amnion phenotype in Smad5 mutants. These results support a model in which loss of Smad5 results paradoxically in gain of Bmp function defects in the amnion.
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Affiliation(s)
- Erika A Bosman
- Department of Developmental Biology (VIB7 for Biotechnology (VIB) and Laboratory of Molecular Biology (Celgen), University of Leuven, B-3000 Leuven, Belgium
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153
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Fox MS, Clark AT, El Majdoubi M, Vigne JL, Urano J, Hostetler CE, Griswold MD, Weiner RI, Reijo Pera RA. Intermolecular interactions of homologs of germ plasm components in mammalian germ cells. Dev Biol 2006; 301:417-31. [PMID: 16996493 PMCID: PMC2563953 DOI: 10.1016/j.ydbio.2006.08.047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Revised: 08/02/2006] [Accepted: 08/18/2006] [Indexed: 10/24/2022]
Abstract
In some species such as flies, worms, frogs and fish, the key to forming and maintaining early germ cell populations is the assembly of germ plasm, microscopically distinct egg cytoplasm that is rich in RNAs, RNA-binding proteins and ribosomes. Cells which inherit germ plasm are destined for the germ cell lineage. In contrast, in mammals, germ cells are formed and maintained later in development as a result of inductive signaling from one embryonic cell type to another. Research advances, using complementary approaches, including identification of key signaling factors that act during the initial stages of germ cell development, differentiation of germ cells in vitro from mouse and human embryonic stem cells and the demonstration that homologs of germ plasm components are conserved in mammals, have shed light on key elements in the early development of mammalian germ cells. Here, we use FRET (Fluorescence Resonance Energy Transfer) to demonstrate that living mammalian germ cells possess specific RNA/protein complexes that contain germ plasm homologs, beginning in the earliest stages of development examined. Moreover, we demonstrate that, although both human and mouse germ cells and embryonic stem cells express the same proteins, germ cell-specific protein/protein interactions distinguish germ cells from precursor embryonic stem cells in vitro; interactions also determine sub-cellular localization of complex components. Finally, we suggest that assembly of similar protein complexes may be central to differentiation of diverse cell lineages and provide useful diagnostic tools for isolation of specific cell types from the assorted types differentiated from embryonic stem cells.
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Affiliation(s)
- Mark S Fox
- Center for Reproductive Sciences, Human Embryonic Stem Cell Research Center, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California at San Francisco, San Francisco, CA 94143-0556, USA
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154
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Kaivo-oja N, Jeffery LA, Ritvos O, Mottershead DG. Smad signalling in the ovary. Reprod Biol Endocrinol 2006; 4:21. [PMID: 16611366 PMCID: PMC1459162 DOI: 10.1186/1477-7827-4-21] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Accepted: 04/12/2006] [Indexed: 02/08/2023] Open
Abstract
It has now been a decade since the first discovery of the intracellular Smad proteins, the downstream signalling molecules of one of the most important growth factor families in the animal kingdom, the transforming growth factor beta (TGF-beta) superfamily. In the ovary, several TGF-beta superfamily members are expressed by the oocyte, granulosa and thecal cells at different stages of folliculogenesis, and they signal mainly through two different Smad pathways in an autocrine/paracrine manner. Defects in the upstream signalling cascade molecules, the ligands and receptors, are known to have adverse effects on ovarian organogenesis and folliculogenesis, but the role of the individual Smad proteins in the proper function of the ovary is just beginning to be understood for example through the use of Smad knockout models. Although most of the different Smad knockouts are embryonic lethal, it is known, however, that in Smad1 and Smad5 knockout mice primordial germ cell development is impaired and that Smad3 deficient mice harbouring a deletion in exon 8 exhibit impaired folliculogenesis and reduced fertility. In this minireview we discuss the role of Smad structure and function in the ovarian context.
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Affiliation(s)
- Noora Kaivo-oja
- Programme for Developmental and Reproductive Biology, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland and Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Luke A Jeffery
- Programme for Developmental and Reproductive Biology, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland and Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Olli Ritvos
- Programme for Developmental and Reproductive Biology, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland and Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - David G Mottershead
- Programme for Developmental and Reproductive Biology, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland and Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland
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155
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Kurokawa H, Aoki Y, Nakamura S, Ebe Y, Kobayashi D, Tanaka M. Time-lapse analysis reveals different modes of primordial germ cell migration in the medaka Oryzias latipes. Dev Growth Differ 2006; 48:209-21. [PMID: 16573738 DOI: 10.1111/j.1440-169x.2006.00858.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Previous studies have shown that medaka primordial germ cells (PGC) are first distinguishable by olvas expression during late gastrulation, and that they migrate to the gonadal region through the lateral plate mesoderm. Here, we demonstrate that medaka nanos expression marks the germ line at early gastrulation stage. By marking the germ line with green fluorescent protein (GFP) fused to the nanos 3' untranslated region, we were able to visualize the behavior of PGC using time-lapse imaging. We show that there are three distinct modes of PGC migration that function at different stages of development. At early gastrulation stage, PGC actively migrate towards the marginal zone, a process that requires the function of a chemokine receptor, CXCR4. However, at late gastrulation stage, PGC change the mode and direction of their movement, as they are carried towards the midline along with somatic cells undergoing convergent movements. After aligning bilaterally, PGC actively migrate to the posterior end of the lateral plate mesoderm. This posterior movement depends on the activity of both HMGCoAR and a ligand of CXCR4, SDF-1a. These results demonstrate that PGC undergo different modes of migration to reach the prospective gonadal region of the embryo.
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Affiliation(s)
- Hiromi Kurokawa
- Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787, Japan
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156
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Selwood L, Johnson MH. Trophoblast and hypoblast in the monotreme, marsupial and eutherian mammal: evolution and origins. Bioessays 2006; 28:128-45. [PMID: 16435291 DOI: 10.1002/bies.20360] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The pregastrula stage mammalian conceptus consists of both embryonic and non-embryonic components. The latter forms the bulk of the tissues, provides nutrition for the developing embryo and also contributes developmental signals that influence events within the embryo itself. Understanding the origins and relationships between the embryonic and extraembryonic cell lineages is thus central to understanding development in mammals. Despite the apparent gross differences in early developmental strategy and form, the conceptuses of eutherian, marsupial and monotreme mammals show some remarkable similarities in the lineage allocation to trophoblast and hypoblast and in the emergent properties of the two cell types. We suggest that the gross differences can be explained by two relatively small evolutionary timing changes affecting cell adhesion patterns and the polarisation of developmentally significant information. These changes result in the conversion of a unilaminar blastocyst to a morula form composed of blastomeres with increased regulatory capacity.
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Affiliation(s)
- Lynne Selwood
- Department of Zoology, University of Melbourne, Vic, Australia
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157
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Vejlsted M, Offenberg H, Thorup F, Maddox-Hyttel P. Confinement and clearance of OCT4 in the porcine embryo at stereomicroscopically defined stages around gastrulation. Mol Reprod Dev 2006; 73:709-18. [PMID: 16541449 DOI: 10.1002/mrd.20461] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the areas of developmental biology and embryonic stem cell research, reliable molecular markers of pluripotency and early lineage commitment are sparse in large animal species. In this study, we present morphological and immunohistochemical findings on the porcine embryo in the period around gastrulation, days 8-17 postinsemination, introducing a stereomicroscopical staging system in this species. In embryos at the expanding hatched blastocyst stage, OCT4 is confined to the inner cell mass. Following detachment of the hypoblast, and formation of the embryonic disk, this marker of pluripotency was selectively observed in the epiblast. A prominent crescent-shaped thickening at the posterior region of the embryonic disk marked the first polarization within this structure reflecting incipient cell ingression. Following differentiation of the epiblast, clearance of OCT4 from the three germ layers was observed at defined stages, suggesting correlations to lineage specification. In the endoderm, clearance of OCT4 was apparent from early during its formation at the primitive streak stage. The endoderm harbored progenitors of the "fourth germ layer," the primordial germ cells (PGCs), the only cells maintaining expression of OCT4 at the end of gastrulation. In the ectodermal and mesodermal cell lineages, OCT4 became undetectable at the neural groove and somite stage, respectively. As in the mouse, PGCs showed onset of c-kit expression when located in extraembryonal compartments. They appeared to follow the endoderm during extraembryonal allocation and the mesoderm on return to the genital ridge.
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Affiliation(s)
- Morten Vejlsted
- Department of Animal and Veterinary Basic Sciences, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark.
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158
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Payer B, Chuva de Sousa Lopes SM, Barton SC, Lee C, Saitou M, Surani MA. Generation ofstella-GFP transgenic mice: A novel tool to study germ cell development. Genesis 2006; 44:75-83. [PMID: 16437550 DOI: 10.1002/gene.20187] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The relationship between germ cells and pluripotent embryonic stem (ES) cells is of particular interest, together with approaches to generate primordial germ cell (PGCs) from ES cells. A critical requirement in these experiments is the ability to unambiguously detect PGCs with the use of, for example, reporter genes. The currently available transgenic reporters do not show exclusive expression in PGCs at their earliest developmental stages. Here we describe the use of germline-restricted expression of stella, which is currently the best marker gene for PGCs. We generated two stella-GFP reporters and show that both transgenes surpass other reporters in terms of timing and specificity of expression in PGCs. Additionally, we demonstrate the usefulness of stella-GFP during the derivation of PGCs from ES cells.
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Affiliation(s)
- Bernhard Payer
- Wellcome Trust/Cancer Research UK Gurdon Institute of Cancer and Developmental Biology, University of Cambridge, Cambridge, United Kingdom
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159
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Kehler J, Hübner K, Schöler HR. Derivation of germ cells from embryonic stem cells. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2006:125-42. [PMID: 16903421 DOI: 10.1007/3-540-31437-7_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Embryonic stem cells (ESCs), derivatives of cells of early mammalian embryos, have proven to be one of the most powerful tools in developmental and stem cell biology. When injected into embryos, ESCs can contribute to tissues derived from all three germ layers and to the germline. Prior studies have successfully shown that ESCs can recapitulate features of embryonic development by spontaneously forming somatic lineages in culture. Amazingly, recently it has been shown that mouse ESCs can also give rise to primordial germ cells (PGCs) in culture that are capable of undergoing meiosis and forming both male and female gametes. While the full potential of these ES-derived germ cells and gametes remains to be demonstrated, these discoveries provide a new approach for studying reproductive biology and medicine.
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Affiliation(s)
- J Kehler
- Germline Development Group, University of Pennsylvania, School of Veterinary Medicine, Center for Animal Transgenesis and Germ Cell Research, Kennett Square 19348, USA
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160
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Abstract
At the first cell fate decision in mammalian development, the origins of trophoblast and embryonic cell lineages are established as the trophectoderm and the inner cell mass (ICM) in the blastocyst. In the trophoblast cell lineage, a subset of the trophectoderm cells maintains the capacity to proliferate and contribute to the extraembryonic ectoderm, the ectoplacental cone, and the secondary giant cells of the early conceptus after implantation, and finally they produce the entire trophoblastic population in the mature placenta. The stem cell population of the trophectoderm lineage can be isolated and maintained in vitro in the presence of fibroblast growth factor 4, heparin, and a feeder layer of mouse embryonic fibroblast cells. These apparently immortal stem cells in culture are termed trophoblast stem (TS) cells, and exhibit the potential to differentiate into multiple trophoblastic cell types in vitro, as well as in vivo. Even after multiple passages, TS cells retain the ability to participate in the normal development of chimeras and contribute exclusively to the trophoblastic component of the placenta and of the parietal yolk sac. The fate of TS cells is strikingly in contrast to that of embryonic stem cells, which never contribute to these tissues. In this chapter, detailed protocols for the isolation and establishment of TS cell lines from blastocysts and their maintenance are described.
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Affiliation(s)
- Mayumi Oda
- Animal Resource Sciences and Veterinary Medical Sciences, Laboratory of Cellular Biochemistry, The University of Tokyo, Japan
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161
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Zhang J, Li L. BMP signaling and stem cell regulation. Dev Biol 2005; 284:1-11. [PMID: 15963490 DOI: 10.1016/j.ydbio.2005.05.009] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Revised: 05/05/2005] [Accepted: 05/06/2005] [Indexed: 12/17/2022]
Abstract
Stem cells play an essential role in cellular specialization and pattern formation during embryogenesis and in tissue regeneration in adults. This is mainly due to a stem cell's ability to replenish itself (self-renewal) and, at the same time, produce differentiated progeny. Realization of these special stem cell features has changed the prospective of the field. However, regulation of stem cell self-renewal and maintenance of its potentiality require a complicated regulatory network of both extracellular cues and intrinsic programs. Understanding how signaling regulates stem cell behavior will shed light on the molecular mechanisms underlying stem cell self-renewal. In this review, we focus on comparing the progress of recent research regarding the roles of the BMP signaling pathway in different stem cell systems, including embryonic stem cells, germline stem cells, hematopoietic stem cells, and intestinal stem cells. We hope this comparison, together with a brief look at other signaling pathways, will bring a more balanced view of BMP signaling in regulation of stem cell properties, and further point to a general principle that self-renewal of stem cells may require a combination of maintenance of proliferation potential, inhibition of apoptosis, and blocking of differentiation.
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Affiliation(s)
- Jiwang Zhang
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
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162
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Turnpenny L, Cameron IT, Spalluto CM, Hanley KP, Wilson DI, Hanley NA. Human embryonic germ cells for future neuronal replacement therapy. Brain Res Bull 2005; 68:76-82. [PMID: 16325007 DOI: 10.1016/j.brainresbull.2005.08.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Stem cell therapy offers exciting potential for ambitious cellular replacement to treat human (h) disease, such as Parkinson's disease, Alzheimer's disease or even replacement of the cell death that follows thromboembolic stroke. The realisation of these treatments requires cellular resources possessing three essential characteristics: (i) self-renewal, (ii) the ability to differentiate to physiologically normal cell types and (iii) lack of tumourigenicity. Here, we describe work on human embryonic germ cells (hEGCs), a population of cells alongside human embryonic stem cells (hESCs) with the potential to address these issues.
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Affiliation(s)
- Lee Turnpenny
- Human Genetics Division, University of Southampton, Southampton SO16 6YD, UK
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163
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Baughman JM, Geijsen N. In Vitro Generation of Germ Cells: New Techniques to Solve Current Issues. Ann N Y Acad Sci 2005; 1061:33-40. [PMID: 16467255 DOI: 10.1196/annals.1336.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Primordial germ cells comprise a privileged cellular class within the embryo charged with the elite task of maintaining species longevity. While in lower organisms germ-cell fate is determined by the allocation of germ plasm, mammalian germ-line differentiation requires extracellular signals that converge upon the proximal epiblast. Studies using mutant mice or explanted embryos have identified some of the factors controlling primordial germ-cell specification, such as members of the BMP family, but considerable gaps still exist in our understanding of the complete signaling network. Comprehensive investigations of mammalian germ-line specification have been hampered by the inaccessibility of this cell population in the early embryo. Recently, however, several labs including our own have derived primordial germ cells from embryonic stem cells in vitro, thus providing a powerful new technique for the study of germ cells. In this review the different methods used for the in vitro generation of germ cells and how these techniques may be improved and applied to further advance our knowledge of germ-cell biology are discussed.
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Affiliation(s)
- Joshua M Baughman
- Graduate Program of Biological and Biomedical Sciences, Harvard Medical School, Boston, MA 02115, USA
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164
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Turnpenny L, Spalluto CM, Perrett RM, O'Shea M, Hanley KP, Cameron IT, Wilson DI, Hanley NA. Evaluating human embryonic germ cells: concord and conflict as pluripotent stem cells. Stem Cells 2005; 24:212-20. [PMID: 16144875 DOI: 10.1634/stemcells.2005-0255] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The realization of cell replacement therapy derived from human pluripotent stem cells requires full knowledge of the starting cell types as well as their differentiated progeny. Alongside embryonic stem cells, embryonic germ cells (EGCs) are an alternative source of pluripotent stem cell. Since 1998, four groups have described the derivation of human EGCs. This review analyzes the progress on derivation, culture, and differentiation, drawing comparison with other pluripotent stem cell populations.
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Affiliation(s)
- Lee Turnpenny
- Early Human Development and Stem Cells Group, University of Southampton, Duthie Building (M.P. 808), Southampton General Hospital, Tremona Road, Southampton SO16 6YD, United Kingdom
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165
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Pangas SA, Rajkovic A. Transcriptional regulation of early oogenesis: in search of masters. Hum Reprod Update 2005; 12:65-76. [PMID: 16143663 DOI: 10.1093/humupd/dmi033] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Transcription factors in the germline play important roles in ovary formation and folliculogenesis, and control both oocyte development and somatic cell function. Factor in the germline (Figla) and newborn ovary homeobox gene (Nobox) represent a growing number of oocyte-specific transcription factors that regulate genes unique to oocytes. Studies on oocyte-specific transcription factors are important in understanding the genetic pathways essential for oogenesis, pluripotency, and embryonic development. Likely, these genes regulate reproductive life span and represent candidate genes for reproductive disorders, such as premature ovarian failure, and infertility. Therefore, oocyte-specific transcription factors, and oocyte-specific genes regulated by such factors, are attractive tissue-specific pharmacological targets to regulate human fertility.
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166
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Berekelya LA, Ponomarev MB, Mikryukov AA, Luchinskaya NN, Belyavsky AV. Molecular Mechanisms of Germ Line Cell Determination in Animals. Mol Biol 2005. [DOI: 10.1007/s11008-005-0073-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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167
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Drummond AE. TGFβ signalling in the development of ovarian function. Cell Tissue Res 2005; 322:107-15. [PMID: 15983782 DOI: 10.1007/s00441-005-1153-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Accepted: 04/20/2005] [Indexed: 11/29/2022]
Abstract
Ovarian development begins back in the embryo with the formation of primordial germ cells and their subsequent migration and colonisation of the genital ridges. Once the ovary has been defined structurally, the primordial germ cells transform into oocytes and become housed in structures called follicles (in this case, primordial follicles), a procedure that, in most mammals, occurs either shortly before or during the first few days after birth. The growth and differentiation of follicles from the primordial population is termed folliculogenesis. Primordial follicles give rise to primary follicles that transform into preantral follicles, then antral follicles (secondary follicles) and, finally (preovulatory) Graafian follicles (tertiary follicles) in a co-ordinated series of transitions regulated by hormones and local intraovarian factors. Members of the transforming growth factor-beta (TGFbeta) superfamily have been shown to play important roles in this developmental process starting with the specification of primordial germ cells by the bone morphogenetic proteins through to the recruitment of primordial follicles by anti-Mullerian hormone and, potentially, growth and differentiation factor-9 (GDF9) and, finally, their transformation into preantral and antral follicles in response to activin and TGF-beta. Developmental and mutant mouse models have been used to show the importance of this family of growth factors in establishing the first wave of folliculogenesis.
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Affiliation(s)
- Ann E Drummond
- Prince Henry's Institute of Medical Research, P.O. Box 5152, Clayton, Victoria 3168, Australia.
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168
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van den Hurk R, Zhao J. Formation of mammalian oocytes and their growth, differentiation and maturation within ovarian follicles. Theriogenology 2005; 63:1717-51. [PMID: 15763114 DOI: 10.1016/j.theriogenology.2004.08.005] [Citation(s) in RCA: 197] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Revised: 07/28/2004] [Accepted: 08/17/2004] [Indexed: 11/25/2022]
Abstract
The limited knowledge on the regulation of oocyte formation, the different steps of folliculogenesis and the required conditions for oocytes to undergo proper growth, differentiation and maturation are major causes of the failure in obtaining viable offspring from in vitro cultured early oocytes from domestic animals and humans. This review highlights the factors that at present are known to be involved in the formation of mammalian oocytes and their growth, differentiation and maturation within ovarian follicles.
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Affiliation(s)
- Robert van den Hurk
- Department of Farm Animal Health, Faculty of Veterinary Medicine, P.O. Box 90151, Yalelaan 7, Utrecht University, Utrecht 3508TD, The Netherlands.
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169
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Abstract
Bone morphogenetic proteins (BMPs) play pleiotropic roles during embryonic development as well as throughout life. Recent genetic approaches especially using the mouse gene knockout system revealed that BMP signaling is greatly involved in early embryonic patterning, which is a dynamic event to establish three-dimensional polarities. The purpose of this review is to describe the diverse function of BMPs through different receptor signaling systems during embryonic patterning including gastrulation and establishment of the left-right asymmetry.
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Affiliation(s)
- Satoshi Kishigami
- Molecular Developmental Biology Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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170
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Rodriguez TA, Srinivas S, Clements MP, Smith JC, Beddington RSP. Induction and migration of the anterior visceral endoderm is regulated by the extra-embryonic ectoderm. Development 2005; 132:2513-20. [PMID: 15857911 DOI: 10.1242/dev.01847] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The anterior visceral endoderm (AVE) is an extra-embryonic tissue required for specifying anterior pattern in the mouse embryo. The AVE is induced at the distal tip of the 5.5 dpc embryo and then migrates to the prospective anterior, where it imparts anterior identity upon the underlying epiblast (the tissue that gives rise to the embryo proper). Little is known about how the AVE is induced and what directs its migration. In this paper, we describe an essential role for another extra-embryonic tissue, the extra-embryonic ectoderm (ExE), in patterning the AVE and epiblast. Removal of the ExE in pre-gastrulation embryos leads to ectopic AVE formation, to a failure of AVE cell migration and to the assumption by the entire epiblast of an anterior identity. Ectopic transplantation of ExE cells inhibits AVE formation and leads to an expansion of the posterior epiblast marker T. These results demonstrate that the ExE restricts the induction of the AVE to the distal tip of the mouse embryo and is required to initiate the migration of these cells to the prospective anterior. Together, these data reveal a novel role for the ExE in the specification of the anteroposterior axis of the mouse embryo.
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Affiliation(s)
- Tristan A Rodriguez
- Molecular Embryology Group, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 ONN, UK.
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171
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Yamaguchi S, Kimura H, Tada M, Nakatsuji N, Tada T. Nanog expression in mouse germ cell development. Gene Expr Patterns 2005; 5:639-46. [PMID: 15939376 DOI: 10.1016/j.modgep.2005.03.001] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Revised: 03/01/2005] [Accepted: 03/01/2005] [Indexed: 11/22/2022]
Abstract
Nanog is a newly identified transcriptional factor bearing a homeodomain and expressed in pluripotential cells of preimplantation and early postimplantation embryos, and embryonic stem (ES) and embryonic germ (EG) cells. Knockout experiments indicate that Nanog functions as a key player in maintaining the pluripotency of stem cells. Importantly, Nanog expression is highly expressed in primordial germ cells (PGCs) of E11.5 and E12.5 mouse embryos. However, its temporal and spatial expression pattern and function in germ cells are largely unknown. To address these issues, whole embryos and cryosections of embryos were immunostained with anti-NANOG and anti-STELLA/PGC7 antibodies. NANOG expression, repressed in colonized PGCs of E7.25-E7.5 embryos, became detectable in migrating PGCs of E7.75-E8.0 embryos. Both male and female PGCs migrating in E9.5 and E10.5 embryos and colonizing the genital ridges of E11.5 and E12.5 embryos were positive for NANOG immunostaining, while the NANOG expression pattern differed between the sexes in the later developmental stage. In female gonadal PGCs of E13.5 and E14.5 embryos, NANOG became undetectable in germ cells positive for the synaptonemal complex-specific protein SCP3, while in male PGCs of E14.5-E16.5 embryos, the number of NANOG-positive germ cells drastically decreased during the mitotic arrest. No germ cells positive for NANOG were detectable in testes and ovaries of adult mice. Thus, in germ cell development, NANOG is expressed in proliferating germ cells, in which nuclear reprogramming is progressing.
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Affiliation(s)
- Shinpei Yamaguchi
- Laboratory of Stem Cell Engineering, Stem Cell Research Center, Institute for Frontier Medical Sciences, Kyoto University, Shogoin, Sakyo-ku, Japan
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172
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Abstract
Because embryonic stem (ES) cells are generally derived by the culture of inner cell mass (ICM) cells, they are often assumed to be the equivalent of ICM cells. However, various evidence indicates that ICM cells transition to a different cell type during ES-cell derivation. Historically, ES cells have been believed to most closely resemble pluripotent primitive ectoderm cells derived directly from the ICM. However, differences between ES cells and primitive ectoderm cells have caused developmental biologists to question whether ES cells really have an in vivo equivalent, or whether their properties merely reflect their tissue culture environment. Here, we review recent evidence that the closest in vivo equivalent of an ES cell is an early germ cell.
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Affiliation(s)
- Thomas P Zwaka
- University of Wisconsin--Medical School and The National Primate Research Center, University of Wisconsin, Madison, WI 53715, USA
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173
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Fatehi AN, van den Hurk R, Colenbrander B, Daemen AJJM, van Tol HTA, Monteiro RM, Roelen BAJ, Bevers MM. Expression of bone morphogenetic protein2 (BMP2), BMP4 and BMP receptors in the bovine ovary but absence of effects of BMP2 and BMP4 during IVM on bovine oocyte nuclear maturation and subsequent embryo development. Theriogenology 2005; 63:872-89. [PMID: 15629804 DOI: 10.1016/j.theriogenology.2004.05.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2004] [Revised: 05/07/2004] [Accepted: 05/12/2004] [Indexed: 11/21/2022]
Abstract
Bone morphogenetic proteins (BMPs) have been implicated in the regulation of ovarian follicular development and are promising candidates to apply in IVM and IVF protocols. We investigated the expression of BMP2, BMP4 and BMP receptors in bovine ovaries and the effects of BMP2 and BMP4 during oocyte maturation on bovine IVM. Reverse transcription polymerase chain reaction studies with antral follicles showed the expression of BMPR-IA, BMPR-IB, ActR-IA, ActR-IIB, BMPR-II and BMP4 mRNA in all follicular compartments, while BMP2 mRNA was generally restricted to theca and cumulus tissue. Immunohistochemistry demonstrated the presence of BMPR-II in oocytes and granulosa cells of preantral follicles but only in oocytes of antral follicles. The immunostaining of BMP2 and BMP4 was limited to theca interna and approximately 25% of oocytes of antral follicles. Exogenously added BMP2 or BMP4 to IVM medium did not affect oocyte nuclear maturation, cumulus cell expansion, nor blastocyst formation following IVF. It is concluded that a BMP-signaling system, consisting of BMP2, BMP4, type II and I receptors, is present in bovine antral follicles and that this system plays a role in development and functioning of these follicles rather than in final oocyte maturation and cumulus expansion.
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Affiliation(s)
- A N Fatehi
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
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174
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Abstract
The mode and timing of germ-cell specification has been studied in diverse organisms, however, the molecular mechanism regulating germ-cell-fate determination remains to be elucidated. In some model organisms, maternal germ-cell determinants play a key role. In mouse embryos, some germ-line-specific gene products exist as maternal molecules and play critical roles in a pluripotential cell population at preimplantation stages. From those cells, primordial germ cells (PGCs) are specified by extracellular signaling mediated by tissue, as well as cell-cell interaction during gastrulation. Thus, establishment of germ-cell lineage in mammalian embryos appears to be regulated by a multistep process, including formation and maintenance of a pluripotential cell population, as well as specification of PGCs. PGCs can be generated from pluripotential embryonic stem (ES) cells in a simple monolayer culture in which tissue interaction does not occur. This raises the possibility that ES cells, as well as, possibly, pluripotential cells in preimplantation embryos, are more closely related to the PGC precursors than pluripotential cells after implantation.
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Affiliation(s)
- Yasuhisa Matsui
- Department of Molecular Embryology, Research Institute, Osaka Medical Center for Maternal and Child Health, Japan.
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175
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Abstract
In sexually reproducing animals all gametes of either sex arise from primordial germ cells (PGC). PGC represent a small cell population, appearing early during embryo development. They represent a key cell population responsible for the survival and the evolution of a species. Indeed, the production of gametes will assure fertilisation and therefore the establishment of the next generation. Until recently only few laboratories were working on PGC biology. A new interest emerged since these cells have the ability to function as pluripotent stem cells when established as cell lines. Indeed, like embryonic stem cells (ESC), embryonic germ cells (EGC) are able to differentiate in a wide variety of tissues. In vivo, EGC are able, after injection into a host blastocyst cavity to colonise the inner cell mass and to participate in embryonic development. In vitro studies in human and mouse have also shown their capacity to differentiate into a large variety of cell types allowing the study of processes involved in cardiomyocyte, haematopoietic, neuronal and myogenic differentiation pathways. We present here the last updates of PGC ontogeny focusing mainly on the murine model.
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Affiliation(s)
- Nadejda Machev
- Institut de Génétique et de biologie moléculaire et cellulaire, CNRS/Inserm/ULP, BP 10142, 1, rue Laurent Fries, 67404 Illkirch Cedex, CU de Strasbourg, France
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176
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Abstract
Many insights into mammalian germ cell development have been gained through genetic engineering and in vivo studies, but the lack of an in vitro system for deriving germ cells has hindered potential advances in germ cell biology. Recent studies have demonstrated embryonic stem cell differentiation into germ cells and more mature gametes, although significant unanswered questions remain about the functionality of these cells. The derivation of germ cells from embryonic stem cells in vitro provides an invaluable assay both for the genetic dissection of germ cell development and for epigenetic reprogramming, and may one day facilitate nuclear transfer technology and infertility treatments.
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Affiliation(s)
- Jason A West
- Graduate Program of Biological and Biomedical Sciences, Harvard Medical School, Boston, Massachusetts 02115, USA
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177
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Hu J, Chen YX, Wang D, Qi X, Li TG, Hao J, Mishina Y, Garbers DL, Zhao GQ. Developmental expression and function of Bmp4 in spermatogenesis and in maintaining epididymal integrity. Dev Biol 2004; 276:158-71. [PMID: 15531371 DOI: 10.1016/j.ydbio.2004.08.034] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2004] [Revised: 08/10/2004] [Accepted: 08/23/2004] [Indexed: 01/14/2023]
Abstract
Bone morphogenetic proteins (BMPs) play essential roles in many aspects of developmental biology. We have previously shown that Bmp7, Bmp8a, and Bmp8b of the 60A class of Bmp genes have additive effects in spermatogenesis and in maintaining the epididymal integrity of the caput and caudal regions. Here we report that Bmp4 of the Dpp class has a unique expression pattern in the developing testis and epididymis. Bmp4 heterozygous males on a largely C57BL/6 background show compromised fertility due to degeneration of germ cells, reduced sperm counts, and decreased sperm motility. More interestingly, some of these males show extensive degeneration of the epididymal epithelium in the corpus region, rather than in the caput and cauda regions as for Bmp7 and Bmp8 mutants. Thus, these genetic data reveal a region-specific requirement of different classes of BMPs for epididymal epithelium to survive and have significant implications on male reproductive health and perhaps birth control.
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Affiliation(s)
- Jie Hu
- Cecil H. and Ida Green Center for Reproductive Biology Sciences, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9051, USA
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178
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Abstract
In mammalian embryos, molecular cross-talk with extraembryonic tissues is essential to elaborate the primary body axes. Here, we review a series of reciprocal interactions that occur shortly after implantation in the uterus, and discuss how they are integrated in a complex signaling network to establish antero-posterior and dorso-ventral polarity. At the heart of this signaling network is the TGFbeta-related protein Nodal which acts on extraembryonic tissues to induce positive and negative feedback regulators at opposite poles of the egg cylinder. This likely results in an activity gradient which is instrumental to pattern the embryo proper.
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Affiliation(s)
- Siew-Lan Ang
- Division of Developmental Neurobiology, NIMR, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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179
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de Sousa Lopes SMC, Roelen BAJ, Monteiro RM, Emmens R, Lin HY, Li E, Lawson KA, Mummery CL. BMP signaling mediated by ALK2 in the visceral endoderm is necessary for the generation of primordial germ cells in the mouse embryo. Genes Dev 2004; 18:1838-49. [PMID: 15289457 PMCID: PMC517404 DOI: 10.1101/gad.294004] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Deletion of various bone morphogenetic proteins (BMPs) and their downstream Smads in mice have clearly shown that BMP signaling is essential for the formation of primordial germ cells (PGCs). However, the molecular mechanism through which this takes place is still unclear. Here, we demonstrate that BMP4 produced in the extraembryonic ectoderm signals through ALK2, a type I BMP receptor, in the visceral endoderm (VE) to induce formation of PGCs from the epiblast. Firstly, embryonic day 5.5-6.0 (E5.5-E6.0) embryos cultured on fibronectin formed PGCs in the presence of VE, but not in its absence. Secondly, Alk2-deficient embryos completely lacked PGCs and the heterozygotes had reduced numbers, resembling Bmp4-deficient phenotypes. Thirdly, expression of constitutively active ALK2 in the VE, but not in the epiblast, was sufficient to rescue the PGC phenotype in Bmp4-deficient embryos. In addition, we show that the requirement for the VE at E5.5-E6.0 can be replaced by culturing embryos stripped of VE on STO cells, indicating that STO cells provide or transduce signals necessary for PGC formation that are normally transmitted by the VE. We propose a model in which direct signaling to proximal epiblast is supplemented by an obligatory indirect BMP-dependent signal via the VE.
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Affiliation(s)
- Susana M Chuva de Sousa Lopes
- Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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180
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Qi X, Li TG, Hao J, Hu J, Wang J, Simmons H, Miura S, Mishina Y, Zhao GQ. BMP4 supports self-renewal of embryonic stem cells by inhibiting mitogen-activated protein kinase pathways. Proc Natl Acad Sci U S A 2004; 101:6027-32. [PMID: 15075392 PMCID: PMC395917 DOI: 10.1073/pnas.0401367101] [Citation(s) in RCA: 308] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The fate of pluripotent stem cells is tightly controlled during early embryonic development. Both the derivation and the maintenance of embryonic stem cells (ES cells) in vitro depend on feeder cell-derived growth factors that are largely unidentified. To dissect the mechanisms governing pluripotency, we conducted a screen to identify factors that are produced by mouse embryonic fibroblast STO cells and are required to maintain the pluripotency of ES cells. One of the factors is bone morphogenetic protein 4 (BMP4). Unexpectedly, the major effect of BMP4 on the self-renewal of ES cells is accomplished by means of the inhibition of both extracellular receptor kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) pathways, and inhibitors of ERK and p38 MAPKs mimic the effect of BMP4 on ES cells. Importantly, inhibition of the p38 MAPK pathway by SB203580 overcomes the block in deriving ES cells from blastocysts lacking a functional Alk3, the BMP type IA receptor. These results uncover a paradigm for BMP signaling in the biology of pluripotent stem cells.
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Affiliation(s)
- Xiaoxia Qi
- Cecil H. and Ida Green Center for Reproductive Biology Sciences and Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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181
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Abstract
Using molecular, cellular, and genetic approaches, recent studies examining the role of the bone morphogenetic protein (BMP) family of growth factors in the reproductive system have led to significant breakthroughs in our understanding of mammalian reproduction and fertility. Gene expression studies have revealed that key components of the BMP system (ligands, receptors, signaling molecules, and binding proteins) exhibit coordinated spatial and temporal expression patterns in fundamental cell types throughout the reproductive system. Availability of recombinant BMPs has enabled functional studies that have demonstrated important biological activities of BMPs in controlling cellular proliferation, differentiation, and apoptosis in reproductive tissues. The physiological importance of the BMP system for mammalian reproduction has been further highlighted by the elucidation of the aberrant reproductive phenotypes of animals with naturally occurring mutations or targeted deletions of certain BMP family genes. Collectively, these studies have established the concept that the BMP system plays a crucial role in fertility in female and male mammals. The purpose of this article is to review the evidence underpinning the importance of the BMP system in mammalian reproduction.
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Affiliation(s)
- Shunichi Shimasaki
- Department of Reproductive Medicine, University of California San Diego, School of Medicine, La Jolla, California 92093-0633, USA.
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182
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Okamura D, Hayashi K, Matsui Y. Mouse epiblasts change responsiveness to BMP4 signal required for PGC formation through functions of extraembryonic ectoderm. Mol Reprod Dev 2004; 70:20-9. [PMID: 15515057 DOI: 10.1002/mrd.20136] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mouse primordial germ cells (PGCs) are initially identified as a cluster of alkaline phosphatase (AP)-positive cells within the extraembryonic mesoderm near the posterior part of the primitive streak at embryonic day (E) 7.25. Clonal analysis of epiblast cells has revealed that the putative precursors of PGCs are localized in the proximal epiblast, and we demonstrated that the conditions required for PGC formation are induced in the proximal region of epiblasts by extraembryonic ectoderm. Bone morphogenetic protein (BMP) 4 and BMP8b, which belong to the transforming growth factor-beta (TGF-beta) superfamily, might generate induction signals from extraembryonic ectoderm. Smad1 and Smad5, which are intracellular signaling molecules for BMP4, might also play a critical role in stimulating epiblasts to form PGC. However, how pluripotential epiblasts temporally and spatially respond to BMP signals to form PGCs remains unclear. The present study examines changes of responsiveness to BMP4 for PGC formation in epiblasts and their molecular mechanisms. We initially examined the effect of recombinant human (rh) BMP4 upon cultured epiblasts at different developmental stages, and found that they acquire the ability to respond to BMP4 signals for PGC formation between E5.25 and E5.5. In addition, such competence was conferred upon epiblasts by the extraembryonic ectoderm. We also showed that the increased expression of Smad1 and the onset of Smad5 expression induced by extraembryonic ectoderm might be responsible for quick acquisition of this competence. Furthermore, we show that only proximal epiblast cells maintain responsiveness to BMP4 for PGC formation at E6.0, and that this is associated with the proximal epiblast-specific expression of Smad5. These results explain why only the proximal region of epiblasts can sustain the ability to form PGCs.
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Affiliation(s)
- Daiji Okamura
- Department of Molecular Embryology, Research Institute, Osaka Medical Center for Maternal and Child Health, Osaka, Japan
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183
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Loebel DAF, Watson CM, De Young RA, Tam PPL. Lineage choice and differentiation in mouse embryos and embryonic stem cells. Dev Biol 2003; 264:1-14. [PMID: 14623228 DOI: 10.1016/s0012-1606(03)00390-7] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The use of embryonic stem (ES) cells for generating healthy tissues has the potential to revolutionize therapies for human disease or injury, for which there are currently no effective treatments. Strategies for manipulating stem cell differentiation should be based on knowledge of the mechanisms by which lineage decisions are made during early embryogenesis. Here, we review current research into the factors influencing lineage differentiation in the mouse embryo and the application of this knowledge to in vitro differentiation of ES cells. In the mouse embryo, specification of tissue lineages requires cell-cell interactions that are influenced by coordinated cell migration and cellular neighborhood mediated by the key WNT, FGF, and TGFbeta signaling pathways. Mimicking the cellular interactions of the embryo by providing appropriate signaling molecules in culture has enabled the differentiation of ES cells to be directed predominately toward particular lineages. Multistep strategies incorporating the provision of soluble factors known to influence lineage choices in the embryo, coculture with other cells or tissues, genetic modification, and selection for desirable cell types have allowed the production of ES cell derivatives that produce beneficial effects in animal models. Increasing the efficiency of this process can only result from a better understanding of the molecular control of cell lineage determination in the embryo.
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Affiliation(s)
- David A F Loebel
- Embryology Unit, Children's Medical Research Institute, Locked Bag 23, Wentworthville, NSW 2145, Australia
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184
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Johnson AD, Crother B, White ME, Patient R, Bachvarova RF, Drum M, Masi T. Regulative germ cell specification in axolotl embryos: a primitive trait conserved in the mammalian lineage. Philos Trans R Soc Lond B Biol Sci 2003; 358:1371-9. [PMID: 14511484 PMCID: PMC1693234 DOI: 10.1098/rstb.2003.1331] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
How germ cells are specified in the embryos of animals has been a mystery for decades. Unlike most developmental processes, which are highly conserved, embryos specify germ cells in very different ways. Curiously, in mouse embryos germ cells are specified by extracellular signals; they are not autonomously specified by maternal germ cell determinants (germ plasm), as are the germ cells in most animal model systems. We have developed the axolotl (Ambystoma mexicanum), a salamander, as an experimental system, because classic experiments have shown that the germ cells in this species are induced by extracellular signals in the absence of germ plasm. Here, we provide evidence that the germ cells in axolotls arise from naive mesoderm in response to simple inducing agents. In addition, by analysing the sequences of axolotl germ-cell-specific genes, we provide evidence that mice and urodele amphibians share a common mechanism of germ cell development that is ancestral to tetrapods. Our results imply that germ plasm, as found in species such as frogs and teleosts, is the result of convergent evolution. We discuss the evolutionary implications of our findings.
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Affiliation(s)
- Andrew D Johnson
- Department of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.
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185
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Affiliation(s)
- Anne McLaren
- The Wellcome Trust/Cancer Research UK Institute of Cancer and Developmental Biology, Tennis Court Road, Cambridge CB2 1QR, UK.
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186
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Abstract
Recent studies in Caenorhabditis elegans implicate PcG- and NuRD-like chromatin regulators in the establishment and maintenance of germline-soma distinctions. Somatic cells appear to utilize NuRD-related nucleosome-remodeling factors to overwrite germline-specific chromatin states that are specified through PcG-like activities. The germline, in turn, may rely on an asymmetrically inherited inhibitor to prevent chromatin reorganization that would otherwise erase pluripotency.
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Affiliation(s)
- Tae Ho Shin
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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187
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Toyooka Y, Tsunekawa N, Akasu R, Noce T. Embryonic stem cells can form germ cells in vitro. Proc Natl Acad Sci U S A 2003; 100:11457-62. [PMID: 14504407 PMCID: PMC208779 DOI: 10.1073/pnas.1932826100] [Citation(s) in RCA: 483] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2003] [Indexed: 11/18/2022] Open
Abstract
Knock-in embryonic stem (ES) cells, in which GFP or lacZ was expressed from the endogenous mouse vasa homolog (Mvh), which is specifically expressed in differentiating germ cells, were used to visualize germ cell production during in vitro differentiation. The appearance of MVH-positive germ cells depended on embryoid body formation and was greatly enhanced by the inductive effects of bone morphogenic protein 4-producing cells. The ES-derived MVH-positive cells could participate in spermatogenesis when transplanted into reconstituted testicular tubules, demonstrating that ES cells can produce functional germ cells in vitro. In vitro germ cell differentiation provides a paradigm for studying the molecular basis of germ line establishment, as well as for developing new approaches to reproductive engineering.
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Affiliation(s)
- Yayoi Toyooka
- Mitsubishi Kagaku Institute of Life Sciences, 11 Minamiooya Machida-shi, Tokyo 194-8511, Japan
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188
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Abstract
Primordial germ cells follow a characteristic developmental path that is manifested in the specialized regulation of basic cell functions and behaviour. Recent studies in zebrafish have greatly enhanced our understanding of the mode of specification of primordial germ cells, cell-fate maintenance and the migration of these cells towards their target, the gonad, where they differentiate into gametes.
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Affiliation(s)
- Erez Raz
- Germ Cell Development, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37070 Goettingen, Germany.
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189
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Pellegrini M, Grimaldi P, Rossi P, Geremia R, Dolci S. Developmental expression of BMP4/ALK3/SMAD5 signaling pathway in the mouse testis: a potential role of BMP4 in spermatogonia differentiation. J Cell Sci 2003; 116:3363-72. [PMID: 12857787 DOI: 10.1242/jcs.00650] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
It is well established that the c-kit gene plays an essential role in the proliferation of differentiating spermatogonia in prepuberal mice. However, the mechanisms that regulate the onset of spermatogenesis, i.e. differentiation of spermatogonial stem cells and c-kit expression, are poorly understood. Here we identify a novel signal transduction system in mouse prepuberal testis regulating this developmental event, involving bone morphogenetic protein 4 (BMP4) and its transduction machinery. BMP4 is produced by Sertoli cells very early in the postnatal life and is successively down regulated in peri-puberal Sertoli cells. Its receptor Alk3 and the R-Smad Smad5 are specifically expressed both in proliferating primordial germ cells and in postnatal spermatogonia. BMP4 stimulation of cultured spermatogonia induces Smad4/5 nuclear translocation and the formation of a DNA-binding complex with the transcriptional coactivator p300/CBP. In vitro exposure of undifferentiated spermatogonia to BMP4 exerts both mitogenic and differentiative effects, inducing [3H]thymidine incorporation and Kit expression. As a result of the latter event, Kit-negative spermatogonia acquire sensitivity to Stem Cell Factor.
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Affiliation(s)
- Manuela Pellegrini
- Dipartimento di Sanita' Pubblica e Biologia Cellulare, Sezione di Anatomia, Universita' di Roma Tor Vergata, Rome, Italy
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190
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Johnson AD, Drum M, Bachvarova RF, Masi T, White ME, Crother BI. Evolution of predetermined germ cells in vertebrate embryos: implications for macroevolution. Evol Dev 2003; 5:414-31. [PMID: 12823457 DOI: 10.1046/j.1525-142x.2003.03048.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The germ line is established in animal embryos with the formation of primordial germ cells (PGCs), which give rise to gametes. Therefore, the need to form PGCs can act as a developmental constraint by inhibiting the evolution of embryonic patterning mechanisms that compromise their development. Conversely, events that stabilize the PGCs may liberate these constraints. Two modes of germ cell determination exist in animal embryos: (a) either PGCs are predetermined by the inheritance of germ cell determinants (germ plasm) or (b) PGCs are formed by inducing signals secreted by embryonic tissues (i.e., regulative determination). Surprisingly, among the major extant amphibian lineages, one mechanism is found in urodeles and the other in anurans. In anuran amphibians PGCs are predetermined by germ plasm; in urodele amphibians PGCs are formed by inducing signals. To determine which mechanism is ancestral to the tetrapod lineage and to understand the pattern of inheritance in higher vertebrates, we used a phylogenetic approach to analyze basic morphological processes in both groups and correlated these with mechanisms of germ cell determination. Our results indicate that regulative germ cell determination is a property of embryos retaining ancestral embryological processes, whereas predetermined germ cells are found in embryos with derived morphological traits. These correlations suggest that regulative germ cell formation is an important developmental constraint in vertebrate embryos, acting before the highly conserved pharyngula stage. Moreover, our analysis suggests that germ plasm has evolved independently in several lineages of vertebrate embryos.
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Affiliation(s)
- Andrew D Johnson
- Division of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.
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191
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Haraguchi S, Tsuda M, Kitajima S, Sasaoka Y, Nomura-Kitabayashid A, Kurokawa K, Saga Y. nanos1: a mouse nanos gene expressed in the central nervous system is dispensable for normal development. Mech Dev 2003; 120:721-31. [PMID: 12834871 DOI: 10.1016/s0925-4773(03)00043-1] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A mouse nanos (nanos1) gene was cloned and its function was examined by generating a gene-knockout mouse. The nanos1 gene encodes an RNA-binding protein, which contains a putative zinc-finger motif that exhibits similarity with other nanos-class genes in vertebrates and invertebrates. Although nanos1 is not detected in primordial germ cells, it is observed in seminiferous tubules of mature testis. Interestingly, maternally expressed nanos1 is observed in substantial amounts in oocytes, but the amount of maternal RNA is rapidly reduced after fertilization, and the transient zygotic nanos1 expression is observed in eight-cell embryos. At 12.5 days postcoitum, nanos1 is re-expressed in the central nervous system and the expression continues in the adult brain, in which the hippocampal formation is the predominant region. The nanos1 -deficient mice develop to term without any detectable abnormality and they are fertile. No significant neural defect is observed in terms of their behavior to date.
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Affiliation(s)
- Seiki Haraguchi
- Department of Microbiology, Shiga University of Medical Science, Seta, Otsu, 520-2192 Shiga, Japan
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192
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Abstract
During spinal cord development, commissural neurons extend their axons ventrally, away from the roof plate. The roof plate is the source of a diffusible repellent that orients commissural axons in vitro and, thus, may regulate the trajectory of commissural axons in vivo. Of three Bmps expressed in the roof plate, BMP7, but not BMP6 or GDF7, mimics the roof plate activity in vitro. We show here that expression of both Bmp7 and Gdf7 by roof plate cells is required for the fidelity of commissural axon growth in vivo. We also demonstrate that BMP7 and GDF7 heterodimerize in vitro and that, under these conditions, GDF7 enhances the axon-orienting activity of BMP7. Our findings suggest that a GDF7:BMP7 heterodimer functions as a roof plate-derived repellent that establishes the initial ventral trajectory of commissural axons.
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Affiliation(s)
- Samantha J Butler
- Department of Physiology and Cellular Biophysics, Center for Neurobiology and Behavior, Columbia University, New York, NY 10032, USA
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193
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Jaruzelska J, Kotecki M, Kusz K, Spik A, Firpo M, Reijo Pera RA. Conservation of a Pumilio-Nanos complex from Drosophila germ plasm to human germ cells. Dev Genes Evol 2003; 213:120-6. [PMID: 12690449 DOI: 10.1007/s00427-003-0303-2] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2002] [Accepted: 12/19/2002] [Indexed: 01/30/2023]
Abstract
Germ cells are the cells which ultimately give rise to mature sperm and eggs. In model organisms such as flies and worms, several genes that are required for formation and maintenance of germ cells have been identified and their interactions are rapidly being delineated. By contrast, little is known of the genes required for development of human germ cells and it is not clear whether findings from model organisms will translate into knowledge of human germ cell development, especially given observations that reproductive pathways may evolve more rapidly than somatic pathways. The Pumilio and Nanos genes have been especially well-characterized in model organisms and encode proteins that interact and are required for development of germ stem cells in one or both sexes. Here we report the first characterization of a mammalian Nanos homolog, human NANOS1 ( NOS1). We show that human NOS1 protein interacts with the human PUMILIO-2 (PUM2) protein via highly conserved domains to form a stable complex. We also show that in men, the NOS1 and PUM2 proteins are particularly abundant in germline stem cells. These observations mirror those in distant species and document for the first time a conserved protein-protein interaction in germ cells from flies to humans. These results suggest the possibility that the interaction of PUM2 and NOS1 may play a conserved role in germ cell development and maintenance in humans as in model organisms.
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Affiliation(s)
- Jadwiga Jaruzelska
- Center for Reproductive Sciences, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California at San Francisco, San Francisco, CA 94143-0546, USA
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194
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Abstract
During the past two decades, a significant amount of data has been accumulated revealing the intriguing functions of bone morphogenetic proteins (BMPs) in all aspects of embryonic development and organogenesis. Numerous genes encoding BMPs, BMP receptors, and their downstream signal transducers have been mutated in the mouse through targeted mutagenesis. This review focuses on what is known about the role of BMP signaling in gastrulation, mesoderm formation, left-right asymmetry, neural patterning, skeletal and limb development, organogenesis, and gametogenesis as revealed by BMP-signaling mutants.
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Affiliation(s)
- Guang-Quan Zhao
- Cecil H. & Ida Green Center for Reproductive Biology Sciences, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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195
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Abstract
In recent years, extraordinary progress has been made in a broad range of reproductive technologies, including spermatogonial transplantation in the male. However, effective procedures for the complete recapitulation of spermatogenesis in vitro, including meiosis, have remained elusive. Such procedures have the potential to facilitate (1) mechanistic studies of spermatogenesis, (2) directed genetic modification of the male germ line, and (3) treatment of male factor infertility. Early studies demonstrated the importance of germ cell-Sertoli association for germ cell survival in vitro. Recently, evidence for male germ cell survival and progression through meiosis has been reported for the rat, mouse, and man. We demonstrated the expression of spermatid-specific genes (protamine and transition protein 1) by alginate-encapsulate neonatal bull testis cells after 10 weeks in culture, suggesting that meiosis had occurred. Although identifiable germ cells in these cultures were very sparse, some indication of acrosome development was observed. Following round spermatid injection (ROSI) with presumptive spermatids produced in vitro, 50% of blastocysts produced were diploid and 37% were Y-chromosome positive. Improved culture conditions, which promote germ cell survival, differentiation, and proliferation, are essential for in vitro spermatogenesis (IVS) to become a useful technology. Other approaches to male germ cell manipulation and spermatid production are discussed.
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Affiliation(s)
- J E Parks
- Gamete Physiology, Department of Animal Science, Cornell University, 201 Morrison Hall, Ithaca, NY 14853, USA.
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196
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Belecky-Adams TL, Adler R, Beebe DC. Bone morphogenetic protein signaling and the initiation of lens fiber cell differentiation. Development 2002; 129:3795-802. [PMID: 12135918 DOI: 10.1242/dev.129.16.3795] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous studies showed that the retina produces factors that promote the differentiation of lens fiber cells, and identified members of the fibroblast growth factor (FGF) and insulin-like growth factor (IGF) families as potential fiber cell differentiation factors. A possible role for the bone morphogenetic proteins (BMPs) is suggested by the presence of BMP receptors in chicken embryo lenses. We have now observed that phosphorylated SMAD1, an indicator of signaling through BMP receptors, localizes to the nuclei of elongating lens fiber cells. Transduction of chicken embryo retinas and/or lenses with constructs expressing noggin, a secreted protein that binds BMPs and prevents their interactions with their receptors, delayed lens fiber cell elongation and increased cell death in the lens epithelium. In an in vitro explant system, in which chicken embryo or adult bovine vitreous humor stimulates chicken embryo lens epithelial cells to elongate into fiber-like cells, these effects were inhibited by noggin-containing conditioned medium, or by recombinant noggin. BMP2, 4, or 7 were able to reverse the inhibition caused by noggin. Lens cell elongation in epithelial explants was stimulated by treatment with FGF1 or FGF2, alone or in combination with BMP2, but not to the same extent as vitreous humor. These data indicate that BMPs participate in the differentiation of lens fiber cells, along with at least one additional, and still unknown factor.
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Affiliation(s)
- Teri Louise Belecky-Adams
- Department of Biology, Indiana University-Purdue University Indianapolis, SL306, Indianapolis, IN 46202, USA
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197
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Saitou M, Barton SC, Surani MA. A molecular programme for the specification of germ cell fate in mice. Nature 2002; 418:293-300. [PMID: 12124616 DOI: 10.1038/nature00927] [Citation(s) in RCA: 627] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Germ cell fate in mice is induced in proximal epiblast cells by the extra-embryonic ectoderm, and is not acquired through the inheritance of any preformed germ plasm. To determine precisely how germ cells are specified, we performed a genetic screen between single nascent germ cells and their somatic neighbours that share common ancestry. Here we show that fragilis, an interferon-inducible transmembrane protein, marks the onset of germ cell competence, and we propose that through homotypic association, it demarcates germ cells from somatic neighbours. Using single-cell gene expression profiles, we also show that only those cells with the highest expression of fragilis subsequently express stella, a gene that we detected exclusively in lineage-restricted germ cells. The stella positive nascent germ cells exhibit repression of homeobox genes, which may explain their escape from a somatic cell fate and the retention of pluripotency.
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Affiliation(s)
- Mitinori Saitou
- Wellcome Trust/Cancer Research UK Institute of Cancer and Developmental Biology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR, UK
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198
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Abstract
Understanding the mechanisms by which the germline is induced and maintained should lead to a broader understanding of the means by which pluripotency is acquired and maintained. In this review, two major aspects of male germ cell development are discussed: underlying mechanisms for induction and maintenance of primordial germ cells and the basic signaling pathways that determine spermatogonial cell fate.
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Affiliation(s)
- Guang Quan Zhao
- Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical School, Dallas, TX 75390, USA
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199
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Abstract
Perinatally, granulosa cells encase individual oocytes within the ovary to form primordial follicles. The initial stages of folliculogenesis are independent of gonadotropins and involve cell-autonomous and non-cell-autonomous factors. Although still poorly understood at a molecular level, successful follicle formation and initiation of follicle growth must involve genetic networks both in germ and in somatic cells. Mouse models offer useful windows into these essential processes. By investigating phenotypes of mouse lines lacking specific gene products, genetic hierarchies that regulate the initial stages of folliculogenesis are being elucidated. These investigations will provide insight into the regulation of mammalian fertility.
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Affiliation(s)
- Olga Epifano
- Laboratory of Cellular and Developmental Biology, NIDDK, NIH, Bethesda, MD 20892-8028, USA.
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200
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Pesce M, Klinger FG, De Felici M. Derivation in culture of primordial germ cells from cells of the mouse epiblast: phenotypic induction and growth control by Bmp4 signalling. Mech Dev 2002; 112:15-24. [PMID: 11850175 DOI: 10.1016/s0925-4773(01)00624-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Primordial germ cells (PGCs) are the embryonic precursors of the gametes of the adult. PGCs derive from cells of the most proximal part of the cup-shaped epiblast corresponding to the presumptive region of the extraembryonic mesoderm. At 7.2 days post coitum (dpc) a small group of PGCs located at the base of the allantois can be recognised due to a strong alkaline phosphatase activity. Thus far, scant information was available on the mechanism(s) controlling the lineage of PGCs in the mouse embryo. However, results obtained in mice defective for bone morphogenetic protein-4 (Bmp4) secreted molecule revealed that this growth factor has important functions for the derivation of PGCs from extraembryonic mesoderm cells. In this paper, we have studied the effects in culture of Bmp4 on epiblast cells obtained from egg-cylinder stage mouse embryos (5.5-6.0 dpc) and PGCs from 11.5 dpc embryos. We found that Bmp4 treatment enables recruitment of pluripotent cells to a PGC phenotype by a multi-step process involving an initial pre-commitment of epiblast cells and a following stage of PGC phenotypic determination. We further provide evidences that Bmp4 may promote the growth of gonadal PGCs through a Smad1/4 signalling.
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Affiliation(s)
- Maurizio Pesce
- Department of Public Health and Cell Biology, Section of Histology and Embryology, University of Rome Tor Vergata, Rome, Italy.
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