51
|
Jia S, Wu D, Xing C, Meng A. Smad2/3 activities are required for induction and patterning of the neuroectoderm in zebrafish. Dev Biol 2009; 333:273-84. [DOI: 10.1016/j.ydbio.2009.06.037] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 06/10/2009] [Accepted: 06/27/2009] [Indexed: 12/15/2022]
|
52
|
Cell communication with the neural plate is required for induction of neural markers by BMP inhibition: evidence for homeogenetic induction and implications for Xenopus animal cap and chick explant assays. Dev Biol 2009; 327:478-86. [PMID: 19162002 DOI: 10.1016/j.ydbio.2008.12.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 12/09/2008] [Accepted: 12/22/2008] [Indexed: 11/20/2022]
Abstract
In Xenopus, the animal cap is very sensitive to BMP antagonists, which result in neuralization. In chick, however, only cells at the border of the neural plate can be neuralized by BMP inhibition. Here we compare the two systems. BMP antagonists can induce neural plate border markers in both ventral Xenopus epidermis and non-neural chick epiblast. However, BMP antagonism can only neuralize ectodermal cells when the BMP-inhibited cells form a continuous trail connecting them to the neural plate or its border, suggesting that homeogenetic neuralizing factors can only travel between BMP-inhibited cells. Xenopus animal cap explants contain cells fated to contribute to the neural plate border and even to the anterior neural plate, explaining why they are so easily neuralized by BMP-inhibition. Furthermore, chick explants isolated from embryonic epiblast behave like Xenopus animal caps and express border markers. We propose that the animal cap assay in Xenopus and explant assays in the chick are unsuitable for studying instructive signals in neural induction.
Collapse
|
53
|
Shintani A, Nakao N, Kakishita K, Itakura T. Generation of dopamine neurons from embryonic stem cells in the presence of the neuralizing activity of bone marrow stromal cells derived from adult mice. J Neurosci Res 2008; 86:2829-38. [DOI: 10.1002/jnr.21748] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
54
|
Sasai Y, Ogushi M, Nagase T, Ando S. Bridging the gap from frog research to human therapy: a tale of neural differentiation in Xenopus animal caps and human pluripotent cells. Dev Growth Differ 2008; 50 Suppl 1:S47-55. [PMID: 18494707 DOI: 10.1111/j.1440-169x.2008.01010.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Over the last decade, much progress has been made toward an understanding of the mechanism of regulation of neural differentiation. In this article, following a brief overview of neural induction research, I would like to discuss the potential contribution of basic embryological research to the progress of human therapeutic development in the present and future, focusing on the medical application of in vitro differentiation of neural tissues. This kind of linkage between basic and medical research will probably be strengthened even more by the recent emergence of human induced pluripotent stem cells. Human pluripotent stem cells are powerful tools for bridging the gap from our accumulated knowledge of embryology to regenerative medicine, as well as to a wide spectrum of medical and pharmaceutical research and development. In this commentary, I describe these issues with a particular emphasis on the contributions made by Japanese scientists.
Collapse
Affiliation(s)
- Yoshiki Sasai
- Organogenesis and Neurogenesis Group, RIKEN Center for Developmental Biology, 2-2-3 Minatojima Minamimachi, Chuo, Kobe 650-0047, Japan.
| | | | | | | |
Collapse
|
55
|
Gaulden J, Reiter JF. Neur-ons and neur-offs: regulators of neural induction in vertebrate embryos and embryonic stem cells. Hum Mol Genet 2008; 17:R60-6. [PMID: 18632699 DOI: 10.1093/hmg/ddn119] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Although the spatial and temporal orchestration of early vertebrate embryogenesis is missing from cell culture systems, recent work suggests that many of the same signals affecting neural induction in vertebrate embryos also regulate embryonic stem (ES) cell neurogenesis. One key regulatory mechanism involved in both in vivo and in vitro neural induction is the inhibition of bone morphogenetic protein (BMP) signals. Wnts and Fibroblast Growth Factors represent additional regulatory influences, which may affect the adoption of neural fates through both BMP-dependent and BMP-independent mechanisms. Insights into neural induction in vivo help to guide paradigms for promoting neural differentiation by ES cells. Conversely, insights into the mechanisms by which ES cells adopt neural fates may provide an improved understanding of neural induction in the early embryo.
Collapse
Affiliation(s)
- Julie Gaulden
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2324, USA
| | | |
Collapse
|
56
|
de Almeida I, Rolo A, Batut J, Hill C, Stern CD, Linker C. Unexpected activities of Smad7 in Xenopus mesodermal and neural induction. Mech Dev 2008; 125:421-31. [PMID: 18359614 DOI: 10.1016/j.mod.2008.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 02/01/2008] [Accepted: 02/04/2008] [Indexed: 11/24/2022]
Abstract
Neural induction is widely believed to be a direct consequence of inhibition of BMP pathways. Because of conflicting results and interpretations, we have re-examined this issue in Xenopus and chick embryos using the powerful and general TGFbeta inhibitor, Smad7, which inhibits both Smad1- (BMP) and Smad2- (Nodal/Activin) mediated pathways. We confirm that Smad7 efficiently inhibits phosphorylation of Smad1 and Smad2. Surprisingly, however, over-expression of Smad7 in Xenopus ventral epidermis induces expression of the dorsal mesodermal markers Chordin and Brachyury. Neural markers are induced, but in a non-cell-autonomous manner and only when Chordin and Brachyury are also induced. Simultaneous inhibition of Smad1 and Smad2 by different approaches does not account for all Smad7 effects, indicating that Smad7 has activities other than inhibition of the TGFbeta pathway. We provide evidence that these effects are independent of Wnt, FGF, Hedgehog and retinoid signalling. We also show that these effects are due to elements outside of the MH2 domain of Smad7. Together, these results indicate that BMP inhibition is not sufficient for neural induction even when Nodal/Activin is also blocked, and that Smad7 activity is considerably more complex than had previously been assumed. We suggest that experiments relying on Smad7 as an inhibitor of TGFbeta-pathways should be interpreted with considerable caution.
Collapse
Affiliation(s)
- Irene de Almeida
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | | | | | | | | | | |
Collapse
|
57
|
Chang C, Harland RM. Neural induction requires continued suppression of both Smad1 and Smad2 signals during gastrulation. Development 2008; 134:3861-72. [PMID: 17933792 DOI: 10.1242/dev.007179] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Vertebrate neural induction requires inhibition of bone morphogenetic protein (BMP) signaling in the ectoderm. However, whether inhibition of BMP signaling is sufficient to induce neural tissues in vivo remains controversial. Here we have addressed why inhibition of BMP/Smad1 signaling does not induce neural markers efficiently in Xenopus ventral ectoderm, and show that suppression of both Smad1 and Smad2 signals is sufficient to induce neural markers. Manipulations that inhibit both Smad1 and Smad2 pathways, including a truncated type IIB activin receptor, Smad7 and Ski, induce early neural markers and inhibit epidermal genes in ventral ectoderm; and co-expression of BMP inhibitors with a truncated activin/nodal-specific type IB activin receptor leads to efficient neural induction. Conversely, stimulation of Smad2 signaling in the neural plate at gastrula stages results in inhibition of neural markers, disruption of the neural tube and reduction of head structures, with conversion of neural to neural crest and mesodermal fates. The ability of activated Smad2 to block neural induction declines by the end of gastrulation. Our results indicate that prospective neural cells are poised to respond to Smad2 and Smad1 signals to adopt mesodermal and non-neural ectodermal fates even at gastrula stages, after the conventionally assigned end of mesodermal competence, so that continued suppression of both mesoderm- and epidermis-inducing Smad signals leads to efficient neural induction.
Collapse
Affiliation(s)
- Chenbei Chang
- Department of Cell Biology, MCLM 360, University of Alabama at Birmingham, Birmingham, AL 35294-0005, USA.
| | | |
Collapse
|
58
|
Aberdam D. Epidermal stem cell fate: what can we learn from embryonic stem cells? Cell Tissue Res 2007; 331:103-7. [PMID: 17805576 DOI: 10.1007/s00441-007-0497-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 08/09/2007] [Indexed: 12/25/2022]
Abstract
Because of its constant renewal and high propensity for repair, the epidermis is, together with the gut and the hematopoietic system, a tissue of choice to explore stem cell biology. Previous research over many years has revealed the complexity of the epidermis: the heterogeneity of the stem cell compartment, with its rare, slowly cycling, multipotent, hair-follicle, "bulge" stem cells and the more restricted interfollicular, follicle-matrix, and sebaceous-gland stem cells, which in turn generate the large pool of transit-amplifying progeny. Stem cell activity has been used for some considerable time to repair skin injuries, but ex-vivo keratinocyte amplification has its limitations, and grafted skin homeostasis is not totally satisfactory. Human embryonic stem cells raise the hope that the understanding of the developmental steps leading to the generation of epidermal stem cells and the characterization of the key signaling pathways involved in skin morphogenesis (such as p63) will be translated into therapeutic benefit. Our recent results suggest the feasibility not only of identifying but also of amplifying human ES cells, early ectodermal progenitors with an intact multipotent potential that might improve the quality and functionality of grafts, provided that preclinical in vivo studies confirm our expectations from in vitro analysis.
Collapse
|
59
|
Xia C, Wang C, Zhang K, Qian C, Jing N. Induction of a high population of neural stem cells with anterior neuroectoderm characters from epiblast-like P19 embryonic carcinoma cells. Differentiation 2007; 75:912-27. [PMID: 17573917 DOI: 10.1111/j.1432-0436.2007.00188.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The epiblast, derived from the inner cell mass (ICM), represents the final embryonic founder cell population of mouse embryo and can give rise to all germ layer lineages including the neuroectoderm. The generation of neural stem cells from epiblast-like cells is of great value for studying the mechanism of neural determination during gastrulation stages of embryonic development. Mouse embryonic carcinoma (EC) P19 cells are equivalent to the epiblast of early post-implantation blastocysts. In this study, we establish a feasible induction system that allows rapid and efficient derivation of a high percentage ( approximately 95%) of neural stem cells from P19 EC cell in N2B27 serum-free medium. The induced neural stem cells bear anterior neuroectoderm characters, and can be efficiently caudalized by retinoic acid (RA). These neural stem cells have multilineage potential to differentiate into neurons, astrocytes, and oligodendrocytes. Mechanistic analysis indicates that inhibition of the bone morphogenetic protein (BMP) pathway may be the main reason for N2B27-neural induction, and that fibroblast growth factor (FGF) signaling is also involved in this process. This method will provide an in vitro system to dissect the molecular mechanisms involved in neural induction of early mouse embryos.
Collapse
Affiliation(s)
- Caihong Xia
- Laboratory of Molecular Cell Biology, Key Laboratory of Stem Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | | | | | | | | |
Collapse
|
60
|
Aberdam D, Gambaro K, Medawar A, Aberdam E, Rostagno P, de la Forest Divonne S, Rouleau M. Embryonic stem cells as a cellular model for neuroectodermal commitment and skin formation. C R Biol 2007; 330:479-84. [PMID: 17631441 DOI: 10.1016/j.crvi.2007.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Revised: 02/09/2007] [Accepted: 03/20/2007] [Indexed: 01/06/2023]
Abstract
Embryonic stem (ES) cells can be differentiated into many cell types in vitro, thus providing a potential unlimited supply of cells for cognitive in vitro studies and cell-based therapy. We recently reported the efficient derivation of ectodermal and epidermal cells from murine ES cells. These differentiated ES cells were able to form, in culture, a multilayered epidermis coupled with an underlying dermal compartment, similar to native skin. We clarified the function of BMP-4 in the binary neuroectodermal choice by stimulating sox-1(+) neural precursors to undergo specific apoptosis while inducing epidermal differentiation through DeltaNp63 gene activation. We further demonstrated that DeltaNp63 enhances ES-derived ectodermal cell proliferation and is necessary for epidermal commitment. This unique cellular model further provides a powerful tool for identifying the molecular mechanisms controlling normal skin development and for investigating p63-ectodermal dysplasia human congenital pathologies.
Collapse
Affiliation(s)
- Daniel Aberdam
- INSERM, U634, faculté de médecine, 28, av. de Valombrose, 06107 Nice cedex 2, France.
| | | | | | | | | | | | | |
Collapse
|
61
|
|
62
|
Heeg-Truesdell E, LaBonne C. Neural induction in Xenopus requires inhibition of Wnt-β-catenin signaling. Dev Biol 2006; 298:71-86. [PMID: 16879817 DOI: 10.1016/j.ydbio.2006.06.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Revised: 06/05/2006] [Accepted: 06/06/2006] [Indexed: 12/22/2022]
Abstract
Canonical Wnt signals have been implicated in multiple events during early embryogenesis, including primary axis formation, neural crest induction, and A-P patterning of the neural plate. The mechanisms by which Wnt signals can direct distinct fates in cell types that are closely linked both temporally and spatially remains poorly understood. However, recent work has suggested that the downstream transcriptional mediators of this pathway, Lef/Tcf family DNA binding proteins, may confer distinct outcomes on these signals in some cellular contexts. In this study, we first examined whether inhibitory mutants of XTcf3 and XLef1 might block distinct Wnt-dependent signaling events during the diversification of cell fates in the early embryonic ectoderm. We found that a Wnt-unresponsive mutant of XTcf3 potently blocks neural crest formation, whereas an analogous mutant of XLef1 does not, and that the difference in activity mapped to the C-terminus of the proteins. Significantly, the inhibitory XTcf3 mutant also blocked expression of markers of anterior-most cell types, including cement gland and sensory placodes, indicating that Wnt signals are required for rostral as well as caudal ectodermal fates. Unexpectedly, we also found that blocking canonical Wnt signals in the ectoderm, using the inhibitory XTcf3 mutant or by other means, dramatically expanded the size of the neural plate, as evidenced by the increased expression of early pan-neural markers such as Sox3 and Nrp1. Conversely, we find that upregulation of canonical Wnt signals interferes with the induction of the neural plate, and this activity can be separated experimentally from Wnt-mediated neural crest induction. Together these findings provide important and novel insights into the role of canonical Wnt signals during the patterning of vertebrate ectoderm and indicate that Wnt inhibition plays a central role in the process of neural induction.
Collapse
Affiliation(s)
- Elizabeth Heeg-Truesdell
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Il 60208, USA
| | | |
Collapse
|
63
|
Wang C, Xia C, Bian W, Liu L, Lin W, Chen YG, Ang SL, Jing N. Cell aggregation-induced FGF8 elevation is essential for P19 cell neural differentiation. Mol Biol Cell 2006; 17:3075-84. [PMID: 16641368 PMCID: PMC1483041 DOI: 10.1091/mbc.e05-11-1087] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
FGF8, a member of the fibroblast growth factor (FGF) family, has been shown to play important roles in different developing systems. Mouse embryonic carcinoma P19 cells could be induced by retinoic acid (RA) to differentiate into neuroectodermal cell lineages, and this process is cell aggregation dependent. In this report, we show that FGF8 expression is transiently up-regulated upon P19 cell aggregation, and the aggregation-dependent FGF8 elevation is pluripotent stem cell related. Overexpressing FGF8 promotes RA-induced monolayer P19 cell neural differentiation. Inhibition of FGF8 expression by RNA interference or blocking FGF signaling by the FGF receptor inhibitor, SU5402, attenuates neural differentiation of the P19 cell. Blocking the bone morphogenetic protein (BMP) pathway by overexpressing Smad6 in P19 cells, we also show that FGF signaling plays a BMP inhibition-independent role in P19 cell neural differentiation.
Collapse
Affiliation(s)
- Chen Wang
- *Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences and Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Caihong Xia
- *Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences and Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Wei Bian
- *Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences and Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Li Liu
- *Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences and Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Wei Lin
- *Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences and Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- Division of Developmental Neurobiology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom; and
| | - Ye-Guang Chen
- Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China
| | - Siew-Lan Ang
- Division of Developmental Neurobiology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom; and
| | - Naihe Jing
- *Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences and Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| |
Collapse
|
64
|
Mackay DR, Hu M, Li B, Rhéaume C, Dai X. The mouse Ovol2 gene is required for cranial neural tube development. Dev Biol 2006; 291:38-52. [PMID: 16423343 PMCID: PMC2891516 DOI: 10.1016/j.ydbio.2005.12.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Revised: 11/23/2005] [Accepted: 12/01/2005] [Indexed: 02/02/2023]
Abstract
The Ovo gene family encodes a group of evolutionarily conserved transcription factors and includes members that reside downstream of key developmental signaling pathways such as Wg/Wnt and BMP/TGF-beta. In the current study, we explore the function of Ovol2, one of three Ovo paralogues in mice. We report that Ovol2 is expressed during early-mid embryogenesis, particularly in the inner cell mass at E3.5, in epiblast at E6.5, and at later stages in ectodermally derived tissues such as the rostral surface (epidermal) ectoderm. Embryos in which Ovol2 is ablated exhibit lethality by E10.5, prior to which they display severe defects including an open cranial neural tube. The neural defects are associated with improper Shh expression in the underlying rostral axial mesoderm and localized changes of neural marker expression along the dorsoventral axis, as well as with expanded cranial neural tissue and reduced cranial surface ectoderm culminating in a lateral shift of the neuroectoderm/surface ectoderm border. We propose that these defects reflect the involvement of Ovol2 in independent processes such as regionalized gene expression and neural/non-neural ectodermal patterning. Additionally, we present evidence that Ovol2 is required for efficient migration and survival of neural crest cells that arise at the neuroectoderm/surface ectoderm border, but not for their initial formation. Collectively, our studies indicate that Ovol2 is a key regulator of neural development and reveal a previously unexplored role for Ovo genes in mammalian embryogenesis.
Collapse
Affiliation(s)
- Douglas R. Mackay
- Department of Biological Chemistry, College of Medicine, D250 Med Sci I, University of California, Irvine, CA 92697-1700, USA
| | - Ming Hu
- Department of Biological Chemistry, College of Medicine, D250 Med Sci I, University of California, Irvine, CA 92697-1700, USA
| | - Baoan Li
- Department of Biological Chemistry, College of Medicine, D250 Med Sci I, University of California, Irvine, CA 92697-1700, USA
| | - Catherine Rhéaume
- Department of Biological Chemistry, College of Medicine, D250 Med Sci I, University of California, Irvine, CA 92697-1700, USA
| | - Xing Dai
- Department of Biological Chemistry, College of Medicine, D250 Med Sci I, University of California, Irvine, CA 92697-1700, USA
- Developmental Biology Center, University of California, Irvine, CA 92697, USA
- Corresponding author. Department of Biological Chemistry, College of Medicine, D250 Med Sci I, University of California, Irvine, CA 92697-1700, USA. Fax: +1 949 824 2688. (X. Dai)
| |
Collapse
|
65
|
Abstract
The prevailing approach within the field of craniofacial development is focused on finding a balance between tissues (e.g., facial epithelia, neuroectoderm, and neural crest) and molecules (e.g., bone morphogenetic proteins, fibroblast growth factors, Wnts) that play a role in sculpting the face. We are rapidly learning that neither these tissues nor molecular signals are able to act in isolation; in fact, molecular cues are constantly reciprocating signals between the epithelia and the neural crest in order to pattern and mold facial structures. More recently, it has been proposed that this crosstalk is often mediated and organized by discrete organizing centers within the tissues that are able to act as a self-contained unit of developmental potential (e.g., the rhombomere and perhaps the ectomere). Whatever the molecules are and however they are interpreted by these tissues, it appears that there is a remarkably conserved mechanism for setting up the initial organization of the facial prominences between species. Regardless of species, all vertebrates appear to have the same basic bauplan. However, sometime during mid-gestation, the vertebrate face begins to exhibit species-specific variations, in large part due to differences in the rates of growth and differentiation of cells comprising the facial prominences. How do these differences arise? Are they due to late changes in molecular signaling within the facial prominences themselves? Or are these late changes a reflection of earlier, more subtle alterations in boundaries and fields that are established at the earliest stages of head formation? We do not have clear answers to these questions yet, but in this chapter we present new studies that shed light on this age-old question. This chapter aims to present the known signals, both on a molecular and cellular level, responsible for craniofacial development while bringing to light the events that may serve to create difference in facial morphology seen from species to species.
Collapse
Affiliation(s)
- Samantha A Brugmann
- Department of Plastic and Reconstructive Surgery, Stanford University, California 94305, USA
| | | | | |
Collapse
|
66
|
Gambaro K, Aberdam E, Virolle T, Aberdam D, Rouleau M. BMP-4 induces a Smad-dependent apoptotic cell death of mouse embryonic stem cell-derived neural precursors. Cell Death Differ 2005; 13:1075-87. [PMID: 16311513 DOI: 10.1038/sj.cdd.4401799] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Embryonic ectoderm is fated to become either neural or epidermal, depending on patterning processes that occur before and during gastrulation. It has been stated that epidermal commitment proceeds from a bone morphogenetic protein-4 (BMP-4)-dependent inhibition of dorsal ectoderm neuralization. We recently demonstrated that murine embryonic stem (ES) cells treated with BMP-4 undergo effective keratinocyte commitment and epidermogenesis. Focusing on the precise role of BMP-4 in the early choice between neural and epidermal commitment, we show here that BMP-4 treatment of ES cells leads to a dramatic apoptotic death of Sox-1+ neural precursors with concomitant epidermal engagement. In addition, neutralization of the Smad pathway prevents both the BMP-4 apoptotic process and the inhibition of neural differentiation. Our results suggest that, in mammals, BMP-4, as an active inducer of epidermal commitment, interferes with the survival of neural precursors through induction of their apoptotic cell death.
Collapse
|
67
|
Kourakis MJ, Smith WC. Did the first chordates organize without the organizer? Trends Genet 2005; 21:506-10. [PMID: 16023252 DOI: 10.1016/j.tig.2005.07.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 05/11/2005] [Accepted: 07/03/2005] [Indexed: 11/21/2022]
Abstract
Models of vertebrate development frequently portray the organizer as acting on a largely unpatterned embryo to induce major components of the body plan, such as the neural plate and somites. Recent experiments examining the molecular and genetic basis of major inductive events of vertebrate embryogenesis force a re-examination of this view. These newer observations, along with a proposed revised fate map for the frog Xenopus laevis, suggest a possible reconciliation between the seemingly disparate mechanisms present in the ontogeny of the common chordate body plan of vertebrate and invertebrate chordates. Here, we review data from vertebrates and from an ascidian urochordate and propose that the organizer was not present at the base of the chordate lineage, but could have been a later innovation in the lineage leading to vertebrates, where its role was more permissive than instructive.
Collapse
Affiliation(s)
- Matthew J Kourakis
- Molecular, Cell and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | | |
Collapse
|
68
|
Thisse B, Thisse C. Functions and regulations of fibroblast growth factor signaling during embryonic development. Dev Biol 2005; 287:390-402. [PMID: 16216232 DOI: 10.1016/j.ydbio.2005.09.011] [Citation(s) in RCA: 360] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 07/29/2005] [Accepted: 09/05/2005] [Indexed: 11/28/2022]
Abstract
Fibroblast growth factors (FGF) are secreted molecules which function through the activation of specific tyrosine kinases receptors, the FGF receptors that transduce the signal by activating different pathways including the Ras/MAP kinase and the phospholipase-C gamma pathways. FGFs are involved in the regulation of many developmental processes including patterning, morphogenesis, differentiation, cell proliferation or migration. Such a diverse set of activities requires a tight control of the transduction signal which is achieved through the induction of different feedback inhibitors such as the Sproutys, Sef and MAP kinase phosphatase 3 which are responsible for the attenuation of FGF signals, limiting FGF activities in time and space.
Collapse
Affiliation(s)
- Bernard Thisse
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, UMR 7104, CNRS/INSERM/ULP, 1 rue Laurent Fries, BP 10142, CU de Strasbourg, 67404 ILLKIRCH cedex, France
| | | |
Collapse
|
69
|
Bouhon IA, Kato H, Chandran S, Allen ND. Neural differentiation of mouse embryonic stem cells in chemically defined medium. Brain Res Bull 2005; 68:62-75. [PMID: 16325006 DOI: 10.1016/j.brainresbull.2005.08.022] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Directed differentiation of embryonic stem (ES) cells has enormous potential to derive a wide variety of defined cell populations of therapeutic value. To achieve this, it is necessary to use protocols that promote cell differentiation under defined culture conditions. Furthermore, understanding the mechanisms of cell differentiation in vitro will allow the development of rationale approaches to systematically manipulate cell fates. Here we have analysed the differentiation of mouse ES cells to the neural lineage under serum and feeder cell-free conditions, using a previously described chemically defined medium (CDM). In CDM, ES cell differentiation is highly neurogenic. Cell differentiation was monitored by analysis of a gene expression array (Clontech-Atlas) and by semi-quantitative RT-PCR for a panel of genes involved in cell lineage specification and patterning of the epiblast. In addition to expression of neural markers, data identified a transient expression of several genes associated with the organising activities of the embryonic node and visceral endoderm, including regulators of WNT, BMP, Hedgehog and FGF signaling pathways. Neural differentiation in CDM does not occur by a simple default mechanism, but was dependent on endogenous FGF signaling, and could be blocked by adding BMP4, and LiCl to simulate WNT activation. Neural differentiation was also inhibited by antagonising endogenous hedgehog activity. Taken together the profile of gene expression changes seen in CDM cultures recapitulates those seen in the early embryo, and is suggestive of common developmental mechanisms.
Collapse
Affiliation(s)
- Isabelle A Bouhon
- Neurobiology Programme, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK.
| | | | | | | |
Collapse
|
70
|
Londin ER, Niemiec J, Sirotkin HI. Chordin, FGF signaling, and mesodermal factors cooperate in zebrafish neural induction. Dev Biol 2005; 279:1-19. [PMID: 15708554 DOI: 10.1016/j.ydbio.2004.11.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Revised: 11/04/2004] [Accepted: 11/09/2004] [Indexed: 12/13/2022]
Abstract
The ectoderm gives rise to both neural tissue and epidermis. In vertebrates, specification of the neural plate requires repression of bone morphogenetic protein (BMP) signaling in the dorsal ectoderm. The extracellular BMP antagonist Chordin and other signals from the dorsal mesoderm play important roles in this process. We utilized zebrafish mutant combinations that disrupt Chordin and mesoderm formation to reveal additional signals that contribute to the establishment of the neural domain. We demonstrate that fibroblast growth factor (FGF) signaling accounts for the additional activity in neural specification. Impeding FGF signaling results in a shift of ectodermal markers from neural to epidermal. However, following inhibition of FGF signaling, expression of anterior neural markers recovers in a Nodal-dependent fashion. Simultaneously blocking, Chordin, mesoderm formation, and FGF signaling eliminates neural marker expression during gastrula stages. We observed that FGF signaling is required for chordin expression but that it also acts via other mechanisms to repress BMP transcription during late blastula stages. Activation of FGF signaling was also able to repress BMP transcription in the absence of protein synthesis. Our results support a model in which specification of anterior neural tissue requires early FGF-mediated repression of BMP transcript levels and later activities of Chordin and mesodermal factors.
Collapse
Affiliation(s)
- Eric R Londin
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY 11794, USA
| | | | | |
Collapse
|
71
|
Shin Y, Kitayama A, Koide T, Peiffer DA, Mochii M, Liao A, Ueno N, Cho KWY. Identification of neural genes usingXenopus DNA microarrays. Dev Dyn 2005; 232:432-44. [PMID: 15614765 DOI: 10.1002/dvdy.20229] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To isolate novel genes regulating neural induction, we used a DNA microarray approach. As neural induction is thought to occur by means of the inhibition of bone morphogenetic protein (BMP) signaling, BMP signaling was inhibited in ectodermal cells by overexpression of a dominant-negative receptor. RNAs were isolated from control animal cap explants and from dominant-negative BMP receptor expressing animal caps and subjected to a microarray experiment using newly generated high-density Xenopus DNA microarray chips representing over 17,000 unigenes. We have identified 77 genes that are induced in animal caps after inhibition of BMP signaling, and all of these genes were subjected to whole-mount in situ hybridization analysis. Thirty-two genes showed specific expression in neural tissues. Of the 32, 14 genes have never been linked to neural induction. Two genes that are highly induced by BMP inhibition are inhibitors of Wnt signaling, suggesting that a key step in neural induction is to produce Wnt antagonists to promote anterior neural plate development. Our current analysis also proves that a microarray approach is useful in identifying novel candidate factors involved in neural induction and patterning.
Collapse
Affiliation(s)
- Yongchol Shin
- Department of Developmental and Cell Biology, University of California, Irvine, California, USA
| | | | | | | | | | | | | | | |
Collapse
|
72
|
Reinhardt B, Broun M, Blitz IL, Bode HR. HyBMP5-8b, a BMP5-8 orthologue, acts during axial patterning and tentacle formation in hydra. Dev Biol 2004; 267:43-59. [PMID: 14975716 DOI: 10.1016/j.ydbio.2003.10.031] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2003] [Revised: 09/18/2003] [Accepted: 10/06/2003] [Indexed: 11/19/2022]
Abstract
Developmental gradients play a central role in axial patterning in hydra. As part of the effort towards elucidating the molecular basis of these gradients as well as investigating the evolution of the mechanisms underlying axial patterning, genes encoding signaling molecules are under investigation. We report the isolation and characterization of HyBMP5-8b, a BMP5-8 orthologue, from hydra. Processes governing axial patterning are continuously active in adult hydra. Expression patterns of HyBMP5-8b in normal animals and during bud formation, hydra's asexual form of reproduction, were examined. These patterns, coupled with changes in patterns of expression in manipulated tissues during head regeneration, foot regeneration as well as under conditions that alter the positional value gradient indicate that the gene is active in two different processes. The gene plays a role in tentacle formation and in patterning the lower end of the body axis.
Collapse
Affiliation(s)
- Beate Reinhardt
- Department of Developmental and Cell Biology, and Developmental Biology Center, University of California, Irvine, Irvine, CA 92697, USA
| | | | | | | |
Collapse
|
73
|
Shimozaki K, Nakashima K, Niwa H, Taga T. Involvement of Oct3/4 in the enhancement of neuronal differentiation of ES cells in neurogenesis-inducing cultures. Development 2003; 130:2505-12. [PMID: 12702663 DOI: 10.1242/dev.00476] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Oct3/4 plays a critical role in maintaining embryonic stem cell pluripotency. Regulatable transgene-mediated sustained Oct3/4 expression in ES cells cultured in serum-free LIF-deficient medium caused accelerated differentiation to neuroectoderm-like cells that expressed Sox2, Otx1 and Emx2 and subsequently differentiated into neurons. Neurogenesis of ES cells is promoted by SDIA (stromal cell-derived inducing activity), which accumulates on the PA6 stromal cell surface. Oct3/4 expression in ES cells was maintained by SDIA whereas without it expression was promptly downregulated. Suppression of Oct3/4 abolished neuronal differentiation even after stimulation by SDIA. In contrast, sustained upregulated Oct3/4 expression enhanced SDIA-mediated neurogenesis of ES cells. Therefore, Oct3/4 appears to promote neuroectoderm formation and subsequent neuronal differentiation from ES cells.
Collapse
Affiliation(s)
- Koji Shimozaki
- Department of Cell Fate Modulation, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, 860-0811, Japan
| | | | | | | |
Collapse
|
74
|
Zhao H, Cao Y, Grunz H. Xenopus X-box binding protein 1, a leucine zipper transcription factor, is involved in the BMP signaling pathway. Dev Biol 2003; 257:278-91. [PMID: 12729558 DOI: 10.1016/s0012-1606(03)00069-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We describe a novel basic leucine zipper transcription factor, XXBP-1, which interacts with BMP-4 in a positive feedback loop. It is a maternal factor and is zygotically expressed in the dorsal blastopore lip and ventral ectoderm with the exception of the prospective neural plate during gastrulation. Overexpression of XXBP-1 leads to ventralization of early embryos as described for BMP-4, and inhibits neuralization of dissociated ectoderm. Consistent with mediating BMP signaling, we show that the ectopic expression of XXBP-1 recovers the expression of epidermal keratin and reverses the dorsalization imposed by truncated BMP receptor type I, indicating that it may act downstream of the BMP receptor. Its effects can be partially mimicked by a fusion construct containing the VP16 activator domain and the XXBP-1 DNA-binding domain. In contrast, fusing the DNA-binding domain to the even-skipped repressor domain leads to upregulation of the neural markers NCAM and nrp-1 in animal cap assay. Taken together, the results suggest a role for XXBP-1 in the control of neural differentiation, possibly as an activator.
Collapse
Affiliation(s)
- Hui Zhao
- Department of Zoophysiology, University of Essen, Universitätsstrasse 5, D-45117 Essen, Germany
| | | | | |
Collapse
|
75
|
Marcelle C, Lesbros C, Linker C. Somite patterning: a few more pieces of the puzzle. Results Probl Cell Differ 2003; 38:81-108. [PMID: 12132400 DOI: 10.1007/978-3-540-45686-5_4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Christophe Marcelle
- University Aix-Marseille II, LGPD, CNRS UMR 6545, Developmental Biology Institute of Marseille, Campus de Luminy, Case 907, 13288 Marseille, France
| | | | | |
Collapse
|
76
|
Souopgui J, Sölter M, Pieler T. XPak3 promotes cell cycle withdrawal during primary neurogenesis in Xenopus laevis. EMBO J 2002; 21:6429-39. [PMID: 12456650 PMCID: PMC136948 DOI: 10.1093/emboj/cdf644] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We have isolated the Xenopus p21-activated kinase 3 (XPak3) by virtue of its expression in the territory of primary neurogenesis in the developing embryo. XPak3, but not the other Pak variants, responds positively to X-Ngnr-1 and negatively to X-Notch-1. A constitutively active form of XPak3, generated by fusing a myristylation signal to the N-terminus (XPak3-myr), induces early cell cycle arrest at high concentrations, while ectopic expression of low amounts induces premature neuronal differentiation. Conversely, XPak3 loss of function achieved by use of an antisense morpholino oligonucleotide increases cell proliferation and inhibits neuronal differentiation; this phenotype is rescued by co-injection of XPak3-myr. We conclude that XPak3 is a novel member of the proneural pathway, functioning downstream of neurogenin to withdraw neuronally programmed cells from the mitotic cell cycle, thus allowing for their differentiation.
Collapse
Affiliation(s)
- Jacob Souopgui
- Institut für Biochemie und Molekulare Zellbiologie, Georg-August-Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany and Department of Biochemistry, Faculty of Science, University of Yaoundé I, PO Box 812, Yaoundé, Cameroon Corresponding author e-mail:
| | - Marion Sölter
- Institut für Biochemie und Molekulare Zellbiologie, Georg-August-Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany and Department of Biochemistry, Faculty of Science, University of Yaoundé I, PO Box 812, Yaoundé, Cameroon Corresponding author e-mail:
| | - Tomas Pieler
- Institut für Biochemie und Molekulare Zellbiologie, Georg-August-Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany and Department of Biochemistry, Faculty of Science, University of Yaoundé I, PO Box 812, Yaoundé, Cameroon Corresponding author e-mail:
| |
Collapse
|
77
|
Balemans W, Van Hul W. Extracellular regulation of BMP signaling in vertebrates: a cocktail of modulators. Dev Biol 2002. [PMID: 12376100 DOI: 10.1006/dbio.2002.0779] [Citation(s) in RCA: 427] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The transforming growth factor-beta (TGF-beta) superfamily contains a variety of growth factors which all share common sequence elements and structural motifs. These proteins are known to exert a wide spectrum of biological responses on a large variety of cell types in both vertebrates and invertebrates. Many of them have important functions during embryonic development in pattern formation and tissue specification, and in adult tissues, they are involved in processes such as wound healing, bone repair, and bone remodeling. The family is divided into two general branches: the BMP/GDF and the TGF-beta/Activin/Nodal branches, whose members have diverse, often complementary effects. It is obvious that an orchestered regulation of different actions of these proteins is necessary for proper functioning. The TGF-beta family members act by binding extracellularly to a complex of serine/threonine kinase receptors, which consequently activate Smad molecules by phosphorylation. These Smads translocate to the nucleus, where they modulate transcription of specific genes. Three levels by which this signaling pathway is regulated could be distinguished. First, a control mechanism exists in the intracellular space, where inhibitory Smads and Smurfs prevent further signaling and activation of target genes. Second, at the membrane site, the pseudoreceptor BAMBI/Nma is able to inhibit further signaling within the cells. Finally, a range of extracellular mediators are identified which modulate the functioning of members of the TGF-beta superfamily. Here, we review the insights in the extracellular regulation of members of the BMP subfamily of secreted growth factors with a major emphasis on vertebrate BMP modulation.
Collapse
Affiliation(s)
- Wendy Balemans
- Department of Medical Genetics, University of Antwerp and University Hospital, Antwerp 2610, Belgium
| | | |
Collapse
|
78
|
Hartman D, Haldin CE, Stott D, Jones EA. Xbra3 elicits the production of neural tissue by a non-BMP-dependent mechanism in Xenopus sp. Mech Dev 2002; 118:65-75. [PMID: 12351171 DOI: 10.1016/s0925-4773(02)00195-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Ectoderm cells in animal caps from Xenopus embryos develop to form either epidermis or neural tissue depending upon their receipt of intercellular signals. To date, several secreted neural inducers have been identified which act through the local inhibition of bone morphogenetic protein (BMP) signaling, preventing differentiation to epidermis and resulting in adoption of neural fate. In this work, we have exploited an interspecies animal cap assay, which enables detection of the effects of signaling molecules produced by cells of one animal cap and influencing development in a second cap cultured in close apposition in a Holtfreter combination. We show that expression of the T-box protein, Xbra3, in one cap causes the production of a factor, which causes adoption of neural fate by cells of the other animal cap. The action of this factor is not inhibited by the over-expression of BMP in cells of the responding animal cap, or by the inhibition of Wnt signaling. These findings suggest the existence of a secreted signaling molecule that is able to induce ectodermal cells to adopt neural fate by a mechanism independent of the inhibition of the BMP or Wnt signaling pathways.
Collapse
Affiliation(s)
- D Hartman
- Developmental Biology Group, Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | | | | | | |
Collapse
|
79
|
Satow R, Chan TC, Asashima M. Molecular cloning and characterization of dullard: a novel gene required for neural development. Biochem Biophys Res Commun 2002; 295:85-91. [PMID: 12083771 DOI: 10.1016/s0006-291x(02)00641-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In a screen for genes expressed in neural tissues and pronephroi, we isolated a novel gene, named dullard. Dullard protein contains the C-terminal conserved domain of NLI-IF (Nuclear LIM Interactor-Interacting Factor), a protein whose function is not yet characterized. Dullard mRNA was maternally derived and localized to the animal hemisphere. At neurula stages, the expression was in neural regions and subsequently localized to neural tissues, branchial arches, and pronephroi. Using antisense morpholino oligonucleotide-mediated inhibition, we showed that dullard was required for neural development. The translational knock-down of dullard resulted in failure of neural tube development and the embryos consequently showed a reduction of head development. Expression of neural marker genes in dullard-inhibited embryos was also suppressed. These results suggest that dullard is necessary for neural development.
Collapse
Affiliation(s)
- Reiko Satow
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
| | | | | |
Collapse
|
80
|
Kawasaki H, Suemori H, Mizuseki K, Watanabe K, Urano F, Ichinose H, Haruta M, Takahashi M, Yoshikawa K, Nishikawa SI, Nakatsuji N, Sasai Y. Generation of dopaminergic neurons and pigmented epithelia from primate ES cells by stromal cell-derived inducing activity. Proc Natl Acad Sci U S A 2002; 99:1580-5. [PMID: 11818560 PMCID: PMC122233 DOI: 10.1073/pnas.032662199] [Citation(s) in RCA: 340] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We previously identified a stromal cell-derived inducing activity (SDIA), which induces differentiation of neural cells, including midbrain tyrosine hydroxylase-positive (TH(+)) dopaminergic neurons, from mouse embryonic stem cells. We report here that SDIA induces efficient neural differentiation also in primate embryonic stem cells. Induced neurons contain TH(+) neurons at a frequency of 35% and produce a significant amount of dopamine. Interestingly, differentiation of TH(+) neurons from undifferentiated embryonic cells occurs much faster in vitro (10 days) than it does in the embryo (approximately 5 weeks). In addition, 8% of the colonies contain large patches of Pax6(+)-pigmented epithelium of the retina. The SDIA method provides an unlimited source of primate cells for the study of pathogenesis, drug development, and transplantation in degenerative diseases such as Parkinson's disease and retinitis pigmentosa.
Collapse
Affiliation(s)
- Hiroshi Kawasaki
- Department of Medical Embryology and Neurobiology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
81
|
Monk CS, Webb SJ, Nelson CA. Prenatal neurobiological development: molecular mechanisms and anatomical change. Dev Neuropsychol 2002; 19:211-36. [PMID: 11530976 DOI: 10.1207/s15326942dn1902_5] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
During prenatal development, the central nervous system is transformed from a thin layer of unspecified tissue into a complex system that can process information and organize actions. There are 8 general mechanisms that permit this transformation: neural induction, neurulation, proliferation, migration, axonal outgrowth, synaptogenesis, differentiation, and apoptosis. These processes as well as the anatomical changes they cause are described. Future research with humans, such as in utero MRI as well as behavioral and electrophysiological testing of infants following specific prenatal perturbations, is suggested to link the findings from molecular approaches to developmental neuropsychology.
Collapse
Affiliation(s)
- C S Monk
- Institute of Child Development, University of Minnesota, USA.
| | | | | |
Collapse
|
82
|
Abstract
Embryonic stem (ES) cells transplanted into the early mouse embryo have the capacity to differentiate into all cell types of the nervous system. A simplified culture system has been developed in which single ES cells transform into neural progenitor cells that go on to form neurospheres. This system is ideally suited for mechanistic studies of the earliest stages of neurogenesis. In this model, signaling via fibroblast growth factor and bone morphogenetic protein family members is important for the first steps of neural progenitor differentiation.
Collapse
Affiliation(s)
- H Q Xian
- Dept of Anatomy and Neurobiology, Box 8108, Washington University School of Medicine, 660 S. Euclid Avenue, St Louis, MO 63110, USA
| | | |
Collapse
|
83
|
Gammill LS, Sive H. otx2 expression in the ectoderm activates anterior neural determination and is required for Xenopus cement gland formation. Dev Biol 2001; 240:223-36. [PMID: 11784058 DOI: 10.1006/dbio.2001.0470] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously showed that otx2 regulates Xenopus cement gland formation in the ectoderm. Here, we show that otx2 is sufficient to direct anterior neural gene expression, and that its activity is required for cement gland and anterior neural determination. otx2 activity at midgastrula activates anterior and prevents expression of posterior and ventral gene expression in whole embryos and ectodermal explants. These data suggest that part of the mechanism by which otx2 promotes anterior determination involves repression of posterior and ventral fates. A dominant negative otx2-engrailed repressor fusion protein (otx2-En) ablates endogenous cement gland formation, and inhibits expression of the mid/hindbrain boundary marker engrailed-2. Ectoderm expressing otx2-En is not able to respond to signals from the mesoderm to form cement gland, and is impaired in its ability to form anterior neural tissue. These results compliment analyses in otx2 mutant mice, indicating a role for otx2 in the ectoderm during anterior neural patterning.
Collapse
Affiliation(s)
- L S Gammill
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, Massachusetts 02142, USA
| | | |
Collapse
|
84
|
Abstract
Neural induction constitutes the initial step in the generation of the vertebrate nervous system. In attempting to understand the principles that underlie this process, two key issues need to be resolved. When is neural induction initiated, and what is the cellular source and molecular nature of the neural inducing signal(s)? Currently, these aspects of neural induction seem to be very different in amphibian and amniote embryos. Here we highlight the similarities and the differences, and we propose a possible unifying mechanism.
Collapse
Affiliation(s)
- S I Wilson
- Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden
| | | |
Collapse
|
85
|
Hartley KO, Hardcastle Z, Friday RV, Amaya E, Papalopulu N. Transgenic Xenopus embryos reveal that anterior neural development requires continued suppression of BMP signaling after gastrulation. Dev Biol 2001; 238:168-84. [PMID: 11784002 DOI: 10.1006/dbio.2001.0398] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In vertebrates, BMP signaling before gastrulation suppresses neural development. Later in development, BMP signaling specifies a dorsal and ventral fate in the forebrain and dorsal fate in the spinal cord. It is therefore possible that a change in the competence of the ectoderm to respond to BMP signaling occurs at some point in development. We report that exposure of the anterior neural plate to BMP4 before gastrulation causes suppression of all neural markers tested. To determine the effects of BMP4 after gastrulation, we misexpressed BMP4 using a Pax-6 promoter fragment in transgenic frog embryos and implanted beads soaked in BMP4 in the anterior neural plate. Suppression of most anterior neural markers was observed. We conclude that most neural genes continue to require suppression of BMP signaling into the neurula stages. Additionally, we report that BMP4 and BMP7 are abundantly expressed in the prechordal mesoderm of the neurula stage embryo. This poses the paradox of how the expression of most neural genes is maintained if they can be inhibited by BMP signaling. We show that at least one gene in the anterior neural plate suppresses the response of the ectoderm to BMP signaling. We propose that the suppressive effect of BMP signaling on the expression of neural genes coupled with localized suppressors of BMP signaling result in the fine-tuning of gene expression in the anterior neural plate.
Collapse
Affiliation(s)
- K O Hartley
- Department of Zoology, Wellcome/CRC Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR, United Kingdom
| | | | | | | | | |
Collapse
|
86
|
Tropepe V, Hitoshi S, Sirard C, Mak TW, Rossant J, van der Kooy D. Direct neural fate specification from embryonic stem cells: a primitive mammalian neural stem cell stage acquired through a default mechanism. Neuron 2001; 30:65-78. [PMID: 11343645 DOI: 10.1016/s0896-6273(01)00263-x] [Citation(s) in RCA: 592] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Little is known about how neural stem cells are formed initially during development. We investigated whether a default mechanism of neural specification could regulate acquisition of neural stem cell identity directly from embryonic stem (ES) cells. ES cells cultured in defined, low-density conditions readily acquire a neural identity. We characterize a novel primitive neural stem cell as a component of neural lineage specification that is negatively regulated by TGFbeta-related signaling. Primitive neural stem cells have distinct growth factor requirements, express neural precursor markers, generate neurons and glia in vitro, and have neural and non-neural lineage potential in vivo. These results are consistent with a default mechanism for neural fate specification and support a model whereby definitive neural stem cell formation is preceded by a primitive neural stem cell stage during neural lineage commitment.
Collapse
Affiliation(s)
- V Tropepe
- Department of Anatomy & Cell Biology, University of Toronto, Ontario M5S 1A8, Toronto, Canada
| | | | | | | | | | | |
Collapse
|
87
|
Altmann CR, Brivanlou AH. Neural patterning in the vertebrate embryo. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 203:447-82. [PMID: 11131523 DOI: 10.1016/s0074-7696(01)03013-3] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The embryonic central nervous system (CNS) is patterned along its antero-posterior, dorsal-ventral, and left-right axes. Along the dorsal-ventral axis, cell fate determination occurs during and following neural tube closure and involves the action of two opposing signaling pathways: SHH ventrally from the notochord and BMP/GDF dorsally from the boundary of neural and nonneural ectoderm and later from the roof plate. In addition, Wnt and retinoic acid signaling have been shown to act in dorsal-ventral patterning; however, their roles are understood in less detail. Along the antero-posterior axis, signals divide the neural tube into four major divisions: forebrain, midbrain, hindbrain, and spinal cord, and these differences can be detected soon after the formation of the neural plate. The FGF, Wnt, and retinoic acid signaling pathways have been implicated in the caudalization of neural tissue. Boundaries of Hox gene expression are observed along the anteroposterior axis and have been suggested to be involved in establishing different identities in the hindbrain and spinal cord. Complex gene expression patterns in the brain suggest the development of neuromeres dividing the brain into different regions that are elaborated further during development. Patterning along the left-right axis occurs concurrently with antero-posterior and dorsal-ventral patterning during gastrulation. A leading candidate for initiating asymmetry is activin, which acts through Nodal and Lefty before any morphological differences are observed. The big challenge will be understanding how these diverse signaling pathways interact both temporally and spatially to generate the complex adult nervous system.
Collapse
Affiliation(s)
- C R Altmann
- The Rockefeller University, New York, New York 10021, USA
| | | |
Collapse
|
88
|
Sasai Y. Regulation of neural determination by evolutionarily conserved signals: anti-BMP factors and what next? Curr Opin Neurobiol 2001; 11:22-6. [PMID: 11179868 DOI: 10.1016/s0959-4388(00)00169-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The evolutionary conservation of Chordin/bone morphogenetic protein (BMP) signaling supports the hypothesis of dorsal-ventral axis inversion of vertebrates and invertebrates, and implies that the invention of a central nervous system occurred only once during animal evolution. This hypothesis is further strengthened by recent findings of the conservation of downstream genes and modifier genes of neural induction. On the other hand, in contrast with such gross conservation, recent data suggest that the requirement for some signals in neural determination may differ even within the vertebrate subphylum.
Collapse
Affiliation(s)
- Y Sasai
- Department of Medical Embryology and Neurobiology, Institute for Frontier Medical Sciences, Kyoto University, Sakyo, Kyoto 606-8507, Japan.
| |
Collapse
|
89
|
Abstract
The Rel/NF-kappa B gene family encodes a large group of transcriptional activators involved in myriad differentiation events, including embryonic development. We have shown previously that Xrel3, a Xenopus Rel/NF-kappa B-related gene, is expressed in the forebrain, dorsal aspect of the mid- and hindbrain, the otocysts and notochord of neurula and larval stage embryos. Overexpression of Xrel3 causes formation of embryonic tumours. We now show that Xrel3-induced tumours and animal caps from embryos injected with Xrel3 RNA express Otx2, Shh and Gli1. Heterodimerisation of a C-terminally deleted mutant of Xrel3 with wild-type Xrel3 inhibits in vitro binding of wild-type Xrel3 to Rel/NF-kappa B consensus DNA sequences. This dominant interference mutant disrupts Shh, Gli1 and Otx2 mRNA patterning and inhibits anterior development when expressed in the dorsal side of zygotes, which is rescued by co-injecting wild-type Xrel3 mRNA. In chick development, Rel activates Shh signalling, which is required for normal limb formation; Shh, Gli1 and Otx2 encode important neural patterning elements in vertebrates. The activation of these genes in tumours by Xrel3 overexpression and the inhibition of their expression and head development by a dominant interference mutant of Xrel3 indicates that Rel/NF-kappa B is required for activation of these genes and for anterior neural patterning in Xenopus.
Collapse
Affiliation(s)
- B B Lake
- Terry Fox Cancer Research Laboratories, Faculty of Medicine, Memorial University of Newfoundland, St John's, Newfoundland A1B 3V6, Canada
| | | | | |
Collapse
|
90
|
Abstract
Vertebrate segmentation initiates with the subdivision of the paraxial mesoderm into a regular array of somites. Recent evidence suggests that the segmentation clock - a biochemical oscillator acting in the unsegmented paraxial mesoderm cells in most vertebrates - controls cyclic Notch signalling, resulting in periodic formation of somite boundaries.
Collapse
Affiliation(s)
- O Pourquié
- Laboratoire de génétique et de physiologie du développement (LGPD). Developmental Biology Institute of Marseille (IBDM). CNRS-INSERM-Université de la méditerranée-AP de Marseille, Campus de Luminy, Marseille, France
| |
Collapse
|
91
|
Kawasaki H, Mizuseki K, Nishikawa S, Kaneko S, Kuwana Y, Nakanishi S, Nishikawa SI, Sasai Y. Induction of midbrain dopaminergic neurons from ES cells by stromal cell-derived inducing activity. Neuron 2000; 28:31-40. [PMID: 11086981 DOI: 10.1016/s0896-6273(00)00083-0] [Citation(s) in RCA: 929] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We have identified a stromal cell-derived inducing activity (SDIA) that promotes neural differentiation of mouse ES cells. SDIA accumulates on the surface of PA6 stromal cells and induces efficient neuronal differentiation of cocultured ES cells in serum-free conditions without use of either retinoic acid or embryoid bodies. BMP4, which acts as an antineuralizing morphogen in Xenopus, suppresses SDIA-induced neuralization and promotes epidermal differentiation. A high proportion of tyrosine hydroxylase-positive neurons producing dopamine are obtained from SDIA-treated ES cells. When transplanted, SDIA-induced dopaminergic neurons integrate into the mouse striatum and remain positive for tyrosine hydroxylase expression. Neural induction by SDIA provides a new powerful tool for both basic neuroscience research and therapeutic applications.
Collapse
Affiliation(s)
- H Kawasaki
- Department of Medical Embryology and Neurobiology, Institute for Frontier Medical Sciences, Kyoto University, Japan
| | | | | | | | | | | | | | | |
Collapse
|
92
|
Umbhauer M, Penzo-Méndez A, Clavilier L, Boucaut J, Riou J. Signaling specificities of fibroblast growth factor receptors in early Xenopus embryo. J Cell Sci 2000; 113 ( Pt 16):2865-75. [PMID: 10910771 DOI: 10.1242/jcs.113.16.2865] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Formation of mesoderm and posterior structures in early Xenopus embryos is dependent on fibroblast growth factor (FGF) signaling. Although several FGF receptors (FGFRs) are expressed in the early embryo, their respective role in these processes remains poorly understood. We provide evidence that FGFR-1 and FGFR-4 signals elicit distinct responses both in naive and neuralized ectodermal cells. We show that naive ectodermal cells expressing a constitutively active chimeric torso-FGFR-1 (t-R1) are converted into mesoderm in a Ras-dependent manner, while those expressing torso-FGFR-4 (t-R4) differentiate into epidermis without significant activation of Erk-1. In neuralized ectoderm, expression of t-R4 causes the up-regulation of the midbrain markers En-2 and Wnt-1, but not of the hindbrain nor the spinal cord markers Krox20 and Hoxb9. Mutation of tyr(776) in the phospholipase C-(gamma) binding consensus sequence YLDL of t-R4 completely abolishes En-2 and Wnt-1 induction. In contrast to t-R4, platelet derived growth factor (PDGF)-dependent FGFR-1 activation in neuralized ectodermal cells expressing a chimeric PDGFR-FGFR-1 receptor results in the expression of Krox20 and Hoxb9. A similar effect is observed when an inducible form of oncogenic Raf is expressed, therefore implicating FGFR-1 and Raf in the transduction of FGF-caudalizing signals in neural tissue. Our results suggest that FGFR-1 and FGFR-4 transduce distinct signals in embryonic cells, and mainly differ in their ability to activate the Ras/MAPK pathway.
Collapse
MESH Headings
- Animals
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Early Growth Response Protein 2
- Ectoderm/physiology
- Embryo, Nonmammalian/physiology
- Gene Expression Regulation, Developmental/physiology
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- In Situ Hybridization
- MAP Kinase Signaling System/physiology
- Mesoderm/physiology
- Mutagenesis/physiology
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Nervous System/embryology
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-raf/genetics
- Proto-Oncogene Proteins c-raf/metabolism
- RNA, Messenger/analysis
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptor, Fibroblast Growth Factor, Type 1
- Receptor, Fibroblast Growth Factor, Type 2
- Receptor, Fibroblast Growth Factor, Type 4
- Receptors, Fibroblast Growth Factor/genetics
- Receptors, Fibroblast Growth Factor/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Up-Regulation/physiology
- Wnt Proteins
- Wnt1 Protein
- Xenopus Proteins
- Xenopus laevis
- Zebrafish Proteins
Collapse
Affiliation(s)
- M Umbhauer
- Laboratoire de Biologie Moléculaire et Cellulaire du Développement, groupe Biologie Expérimentale, UMR CNRS 7622, Université Paris VI, 75005 Paris, France
| | | | | | | | | |
Collapse
|
93
|
Gammill LS, Sive H. Coincidence of otx2 and BMP4 signaling correlates with Xenopus cement gland formation. Mech Dev 2000; 92:217-26. [PMID: 10727860 DOI: 10.1016/s0925-4773(99)00342-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
We previously showed that otx2 activates ectopic formation of the Xenopus cement gland only in ventrolateral ectoderm, defining a region of the embryo permissive for cement gland formation. In this paper, we explore the molecular identity of this permissive area. One candidate permissive factor is BMP4, whose putative graded inhibition by factors such as noggin has been proposed to activate both cement gland and neural fates. Several lines of evidence are presented to suggest that BMP signaling and otx2 work together to activate cement gland formation. First, BMP4 is highly expressed in the cement gland primordium together with otx2. Second, cement gland formation in isolated ectoderm is always accompanied by coexpression of otx2 and BMP4 RNA, whether cement gland is induced by otx2 or by the BMP protein inhibitor noggin. Third, BMP signaling can modulate otx2 activity, such that increasing BMP signaling preferentially inhibits neural induction by otx2, while decreasing BMP signaling prevents cement gland formation. In addition, we show that a hormone-inducible otx2 activates both ectopic neural and cement gland formation within the cement gland permissive region, in a pattern reminiscent of that found in the embryo. We discuss this observation in view of a model that BMP4 and otx2 work together to promote cement gland formation.
Collapse
Affiliation(s)
- L S Gammill
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
| | | |
Collapse
|
94
|
Hensey C, Gautier J. Developmental regulation of induced and programmed cell death in Xenopus embryos. Ann N Y Acad Sci 2000; 887:105-19. [PMID: 10668468 DOI: 10.1111/j.1749-6632.1999.tb07926.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have analyzed the role of cell death during early Xenopus development and have identified two distinct types of cell death programs during the period between fertilization and the tadpole stage. One is a maternal cell death program that is activated at the onset of gastrulation following damage to the pre-midblastula transition embryo, resulting in the death of non-viable cells. The activation of this cell death program at a specific time during development is a maternally programmed event under the control of a developmental timer set at fertilization, and does not depend on the type of stress applied, on cell cycle progression, or de novo protein synthesis. Subsequently, a second program corresponding to programmed cell death is initiated as part of the normal development of the embryo. Programmed cell death starts at the onset of gastrulation and we have analyzed its spatio-temporal patterns by a whole-mount in situ DNA end labeling technique (the TUNEL protocol).
Collapse
Affiliation(s)
- C Hensey
- Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
| | | |
Collapse
|
95
|
Kishi M, Mizuseki K, Sasai N, Yamazaki H, Shiota K, Nakanishi S, Sasai Y. Requirement of Sox2-mediated signaling for differentiation of early Xenopus neuroectoderm. Development 2000; 127:791-800. [PMID: 10648237 DOI: 10.1242/dev.127.4.791] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
From early stages of development, Sox2-class transcription factors (Sox1, Sox2 and Sox3) are expressed in neural tissues and sensory epithelia. In this report, we show that Sox2 function is required for neural differentiation of early Xenopus ectoderm. Microinjection of dominant-negative forms of Sox2 (dnSox2) mRNA inhibits neural differentiation of animal caps caused by attenuation of BMP signals. Expression of dnSox2 in developing embryos suppresses expression of N-CAM and regional neural markers. We have analyzed temporal requirement of Sox2-mediated signaling by using an inducible dnSox2 construct fused to the ligand-binding domain of the glucocorticoid receptor. Attenuation of Sox2 function both from the late blastula stage and from the late gastrula stage onwards causes an inhibition of neural differentiation in animal caps and in whole embryos. Additionally, dnSox2-injected cells that fail to differentiate into neural tissues are not able to adopt epidermal cell fate. These data suggest that Sox2-class genes are essential for early neuroectoderm cells to consolidate their neural identity during secondary steps of neural differentiation.
Collapse
Affiliation(s)
- M Kishi
- Department of Biological Sciences, Institute for Frontier Medical Sciences, Kyoto University, Sakyo, Kyoto 606-8397, Japan
| | | | | | | | | | | | | |
Collapse
|
96
|
Hata A, Seoane J, Lagna G, Montalvo E, Hemmati-Brivanlou A, Massagué J. OAZ uses distinct DNA- and protein-binding zinc fingers in separate BMP-Smad and Olf signaling pathways. Cell 2000; 100:229-40. [PMID: 10660046 DOI: 10.1016/s0092-8674(00)81561-5] [Citation(s) in RCA: 360] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have identified the 30-zinc finger protein OAZ as a DNA-binding factor that associates with Smads in response to BMP2, forming a complex that transcriptionally activates the homeobox regulator of Xenopus mesoderm and neural development, Xvent-2. OAZ contains a BMP signaling module formed by two clusters of fingers that bind Smads and the Xvent-2 BMP response element, respectively. Previously implicated as a transcriptional partner of Olf-1/EBF in olfactory epithelium and lymphocyte development in the rat, OAZ fulfills this role through clusters of fingers that are separate from the BMP signaling module. The mutually exclusive use of OAZ by the BMP-Smad and Olf pathways illustrates the dual role of a multi-zinc finger protein in signal transduction during development.
Collapse
Affiliation(s)
- A Hata
- Cell Biology Program, Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
| | | | | | | | | | | |
Collapse
|
97
|
Abstract
Endoderm, one of the three principal germ layers, contributes to all organs of the alimentary tract. For simplicity, this review divides formation of endodermal organs into four fundamental steps: (a) formation of endoderm during gastrulation, (b) morphogenesis of a gut tube from a sheet of cells, (c) budding of organ domains from the tube, and (d) differentiation of organ-specific cell types within the growing buds. We discuss possible mechanisms that regulate how undifferentiated endoderm becomes specified into a myriad of cell types that populate the respiratory and gastrointestinal tracts.
Collapse
Affiliation(s)
- J M Wells
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
| | | |
Collapse
|
98
|
Schneider C, Wicht H, Enderich J, Wegner M, Rohrer H. Bone morphogenetic proteins are required in vivo for the generation of sympathetic neurons. Neuron 1999; 24:861-70. [PMID: 10624949 DOI: 10.1016/s0896-6273(00)81033-8] [Citation(s) in RCA: 216] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Bone morphogenetic proteins (BMPs) induce autonomic neurogenesis in neural crest cultures and stimulate sympathetic neuron development when overexpressed in vivo. We demonstrate that inhibition of BMPs in the chick embryo bythe BMP antagonist Noggin prevents sympathetic neuron generation. In Noggin-treated embryos, the noradrenergic marker genes tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH), panneuronal neurofilament 160 (NF160) and SCG10 genes, and the transcriptional regulators Phox2b and Phox2a are not expressed in sympathetic ganglia. Whereas initial ganglion development is not affected, the expression of the basic helix-loop-helix transcription factor Cash-1 is strongly reduced. These results demonstrate that BMPs are essential for sympathetic neuron development and establish Cash-1 and Phox2 genes as downstream effectors of BMPs in this lineage.
Collapse
Affiliation(s)
- C Schneider
- Max-Planck-Institut für Hirnforschung, Abteilung Neurochemie, Frankfurt/Main, Germany
| | | | | | | | | |
Collapse
|
99
|
Abstract
p300/ CREB-binding protein (CBP) is a transcriptional coactivator for a plethora of transcription factors and plays critical roles in signal transduction pathways. We report that the inhibition of p300/CBP function in the Xenopus embryo abolishes non-neural tissue formation and, strikingly, initiates neural induction and primary neurogenesis in the entire embryo. The observed neuralization is achieved in the absence of anterior or posterior gene expression, suggesting that neural fate activation and anterior patterning may represent distinct molecular events. We further demonstrate that the neuralizing and anteriorizing activities of chordin and noggin are separable properties of these neural inducers. This study reveals that all embryonic cells possess intrinsic neuralizing capability and that p300/CBP function is essential for embryonic germ layer formation and neural fate suppression during vertebrate embryogenesis.
Collapse
|
100
|
Abstract
Two types of genes activated by neural inducers have been identified, those that lead to the activation of proneural genes and those that limit the activity of these genes to specific domains in the neural plate. The analysis of these genes has begun to fill gaps in our understanding of events that lead from neural induction to the generation of neurons within three longitudinal columns in the Xenopus and zebrafish neural plate.
Collapse
Affiliation(s)
- A B Chitnis
- Laboratory of Molecular Genetics National Institute of Child Health and Human Development National Institutes of Health Unit on Vertebrate Neural Development, Bethesda Maryland 20892 USA.
| |
Collapse
|