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Hudson C, Yasuo H. Neuromesodermal Lineage Contribution to CNS Development in Invertebrate and Vertebrate Chordates. Genes (Basel) 2021; 12:genes12040592. [PMID: 33920662 PMCID: PMC8073528 DOI: 10.3390/genes12040592] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022] Open
Abstract
Ascidians are invertebrate chordates and the closest living relative to vertebrates. In ascidian embryos a large part of the central nervous system arises from cells associated with mesoderm rather than ectoderm lineages. This seems at odds with the traditional view of vertebrate nervous system development which was thought to be induced from ectoderm cells, initially with anterior character and later transformed by posteriorizing signals, to generate the entire anterior-posterior axis of the central nervous system. Recent advances in vertebrate developmental biology, however, show that much of the posterior central nervous system, or spinal cord, in fact arises from cells that share a common origin with mesoderm. This indicates a conserved role for bi-potential neuromesoderm precursors in chordate CNS formation. However, the boundary between neural tissue arising from these distinct neural lineages does not appear to be fixed, which leads to the notion that anterior-posterior patterning and neural fate formation can evolve independently.
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Ravanelli AM, Kearns CA, Powers RK, Wang Y, Hines JH, Donaldson MJ, Appel B. Sequential specification of oligodendrocyte lineage cells by distinct levels of Hedgehog and Notch signaling. Dev Biol 2018; 444:93-106. [PMID: 30347186 DOI: 10.1016/j.ydbio.2018.10.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/11/2018] [Accepted: 10/11/2018] [Indexed: 01/18/2023]
Abstract
During development of the central nervous system oligodendrocyte precursor cells (OPCs) give rise to both myelinating oligodendrocytes and NG2 glia, which are the most proliferative cells in the adult mammalian brain. NG2 glia retain characteristics of OPCs, and some NG2 glia produce oligodendrocytes, but many others persist throughout adulthood. Why some OPCs differentiate as oligodendrocytes during development whereas others persist as OPCs and acquire characteristics of NG2 glia is not known. Using zebrafish spinal cord as a model, we found that OPCs that differentiate rapidly as oligodendrocytes and others that remain as OPCs arise in sequential waves from distinct neural progenitors. Additionally, oligodendrocyte and persistent OPC fates are specified during a defined critical period by small differences in Shh signaling and Notch activity, which modulates Shh signaling response. Thus, our data indicate that OPCs fated to produce oligodendrocytes or remain as OPCs during development are specified as distinct cell types, raising the possibility that the myelinating potential of OPCs is set by graded Shh signaling activity.
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Affiliation(s)
- Andrew M Ravanelli
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Christina A Kearns
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Rani K Powers
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Yuying Wang
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jacob H Hines
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Maranda J Donaldson
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Bruce Appel
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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3
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Farreny MA, Agius E, Bel-Vialar S, Escalas N, Khouri-Farah N, Soukkarieh C, Danesin C, Pituello F, Cochard P, Soula C. FGF signaling controls Shh-dependent oligodendroglial fate specification in the ventral spinal cord. Neural Dev 2018. [PMID: 29519242 PMCID: PMC5842613 DOI: 10.1186/s13064-018-0100-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Background Most oligodendrocytes of the spinal cord originate from ventral progenitor cells of the pMN domain, characterized by expression of the transcription factor Olig2. A minority of oligodendrocytes is also recognized to emerge from dorsal progenitors during fetal development. The prevailing view is that generation of ventral oligodendrocytes depends on Sonic hedgehog (Shh) while dorsal oligodendrocytes develop under the influence of Fibroblast Growth Factors (FGFs). Results Using the well-established model of the chicken embryo, we show that ventral spinal progenitor cells activate FGF signaling at the onset of oligodendrocyte precursor cell (OPC) generation. Inhibition of FGF receptors at that time appears sufficient to prevent generation of ventral OPCs, highlighting that, in addition to Shh, FGF signaling is required also for generation of ventral OPCs. We further reveal an unsuspected interplay between Shh and FGF signaling by showing that FGFs serve dual essential functions in ventral OPC specification. FGFs are responsible for timely induction of a secondary Shh signaling center, the lateral floor plate, a crucial step to create the burst of Shh required for OPC specification. At the same time, FGFs prevent down-regulation of Olig2 in pMN progenitor cells as these cells receive higher threshold of the Shh signal. Finally, we bring arguments favoring a key role of newly differentiated neurons acting as providers of the FGF signal required to trigger OPC generation in the ventral spinal cord. Conclusion Altogether our data reveal that the FGF signaling pathway is activated and required for OPC commitment in the ventral spinal cord. More generally, our data may prove important in defining strategies to produce large populations of determined oligodendrocyte precursor cells from undetermined neural progenitors, including stem cells. In the long run, these new data could be useful in attempts to stimulate the oligodendrocyte fate in residing neural stem cells.
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Affiliation(s)
- Marie-Amélie Farreny
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France
| | - Eric Agius
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France
| | - Sophie Bel-Vialar
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France
| | - Nathalie Escalas
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France
| | - Nagham Khouri-Farah
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France
| | - Chadi Soukkarieh
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France
| | - Cathy Danesin
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France
| | - Fabienne Pituello
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France
| | - Philippe Cochard
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France
| | - Cathy Soula
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, F-31062, Toulouse, France.
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Xu L, Long J, Shi C, Zhang N, Lv Y, Feng J, Xuan A, He X, Li Q, Bai Y, Liu S, Long D. Effect of leukocyte inhibitory factor on neuron differentiation from human induced pluripotent stem cell-derived neural precursor cells. Int J Mol Med 2018; 41:2037-2049. [PMID: 29393372 PMCID: PMC5810244 DOI: 10.3892/ijmm.2018.3418] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 01/05/2018] [Indexed: 12/27/2022] Open
Abstract
Direct derivation of human induced pluripotent stem cells into neural precursor cells and differentiation of these into neurons holds great promise in the cell therapy of neuro-degenerative diseases. However, the availability and survival rate of neurons requires improvement. In the present study, it was found that the addition of 5 ng/ml leukocyte inhibitory factor (LIF) during the process of differentiation significantly improved the expression of neuron-specific class III β-tubulin (TUJ1) and microtubule-associated protein 2 (MAP2), as detected by immunofluorescence and western blotting. In addition, LIF improved the cell viability, increased the expression of phosphorylated-protein kinase B (AKT), downregulated the expression of proinflammatory cytokines, including interleukin-1α (IL-1α) and tumor necrosis factor-α (TNF-α), and upregulated the expression of anti-inflammatory cytokines, including interleukin-10 (IL-10) and transforming growth factor-β (TGF-β). After adding the phosphatidylinositol 3-kinase (PI3K)/AKT signaling inhibitor LY294002 or wortmannin to the LIF differentiation group, LIF-induced changes in the protein expression of TUJ1 and MAP2 were reversed, but this effect could not be prevented by rapamycin, a mechanistic target of rapamycin signaling inhibitor. The expression of cytokines associated with inflammation and cell viability was reversed by LY294002 and wortmannin, but not by rapamycin. In conclusion, LIF could improve neuronal differentiation and survival through the activation of PI3K/AKT signaling and the anti-inflammatory effect. The anti-inflammatory effect may be mediated by the activation of PI3K/AKT.
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Affiliation(s)
- Liping Xu
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Jingyi Long
- Institute of Neuroscience and The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Chun Shi
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Nianping Zhang
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Ying Lv
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Junda Feng
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Aiguo Xuan
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Xiaosong He
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Qingqing Li
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Yinshan Bai
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Shanshan Liu
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - Dahong Long
- Key Laboratory of Neuroscience, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
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Danesin C, Soula C. Moving the Shh Source over Time: What Impact on Neural Cell Diversification in the Developing Spinal Cord? J Dev Biol 2017; 5:jdb5020004. [PMID: 29615562 PMCID: PMC5831764 DOI: 10.3390/jdb5020004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 03/29/2017] [Accepted: 04/06/2017] [Indexed: 12/18/2022] Open
Abstract
A substantial amount of data has highlighted the crucial influence of Shh signalling on the generation of diverse classes of neurons and glial cells throughout the developing central nervous system. A critical step leading to this diversity is the establishment of distinct neural progenitor cell domains during the process of pattern formation. The forming spinal cord, in particular, has served as an excellent model to unravel how progenitor cells respond to Shh to produce the appropriate pattern. In recent years, considerable advances have been made in our understanding of important parameters that control the temporal and spatial interpretation of the morphogen signal at the level of Shh-receiving progenitor cells. Although less studied, the identity and position of Shh source cells also undergo significant changes over time, raising the question of how moving the Shh source contributes to cell diversification in response to the morphogen. Here, we focus on the dynamics of Shh-producing cells and discuss specific roles for these time-variant Shh sources with regard to the temporal events occurring in the receiving field.
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Affiliation(s)
- Cathy Danesin
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, 31520 Toulouse, France.
| | - Cathy Soula
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, 31520 Toulouse, France.
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6
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Lipid-laden cells differentially distributed in the aging brain are functionally active and correspond to distinct phenotypes. Sci Rep 2016; 6:23795. [PMID: 27029648 PMCID: PMC4814830 DOI: 10.1038/srep23795] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 03/14/2016] [Indexed: 12/21/2022] Open
Abstract
We characterized cerebral Oil Red O-positive lipid-laden cells (LLC) of aging mice evaluating their distribution, morphology, density, functional activities and inflammatory phenotype. We identified LLC in meningeal, cortical and neurogenic brain regions. The density of cerebral LLC increased with age. LLC presenting small lipid droplets were visualized adjacent to blood vessels or deeper in the brain cortical and striatal parenchyma of aging mice. LLC with larger droplets were asymmetrically distributed in the cerebral ventricle walls, mainly located in the lateral wall. We also found that LLC in the subventricular region co-expressed beclin-1 or LC3, markers for autophagosome or autophagolysosome formation, and perilipin (PLIN), a lipid droplet-associated protein, suggesting lipophagic activity. Some cerebral LLC exhibited β galactosidase activity indicating a senescence phenotype. Moreover, we detected production of the pro-inflammatory cytokine TNF-α in cortical PLIN+ LLC. Some cortical NeuN+ neurons, GFAP+ glia limitans astrocytes, Iba-1+ microglia and S100β+ ependymal cells expressed PLIN in the aging brain. Our findings suggest that cerebral LLC exhibit distinct cellular phenotypes and may participate in the age-associated neuroinflammatory processes.
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7
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Li M, Zou Y, Lu Q, Tang N, Heng A, Islam I, Tong HJ, Dawe GS, Cao T. Efficient derivation of dopaminergic neurons from SOX1⁻ floor plate cells under defined culture conditions. J Biomed Sci 2016; 23:34. [PMID: 26956435 PMCID: PMC4782356 DOI: 10.1186/s12929-016-0251-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 02/25/2016] [Indexed: 12/03/2022] Open
Abstract
Background Parkinson’s disease (PD) is a severe neurodegenerative disease associated with loss of dopaminergic neurons. Derivation of dopaminergic neurons from human embryonic stem cells (hESCs) could provide new therapeutic options for PD therapy. Dopaminergic neurons are derived from SOX− floor plate (FP) cells during embryonic development in many species and in human cell culture in vitro. Early treatment with sonic hedgehog (Shh) has been reported to efficiently convert hESCs into FP lineages. Methods In this study, we attempted to utilize a Shh-free approach in deriving SOX1− FP cells from hESCs in vitro. Neuroectoderm conversion from hESCs was achieved with dual inhibition of the BMP4 (LDN193189) and TGF-β signaling pathways (SB431542) for 24 h under defined culture conditions. Results Following a further 5 days of treatment with LDN193189 or LDN193189 + SB431542, SOX1− FP cells constituted 70–80 % of the entire cell population. Upon treatment with Shh and FGF8, the SOX1− FP cells were efficiently converted to functional Nurr1+ and TH+ dopaminergic cells (patterning), which constituted more than 98 % of the entire cell population. However, when the same growth factors were applied to SOX1+ cells, only less than 4 % of the cells became Nurr1+, indicating that patterning was effective only if SOX1 expression was down-regulated. After transplanting the Nurr1+ and TH+ cells into a hemiparkinsonian rat model, significant improvements were observed in amphetamine induced ipslateral rotations, apomorphine induced contra-lateral rotations and Rota rod motor tests over a duration of 8 weeks. Conclusions Our findings thus provide a convenient approach to FP development and functional dopaminergic neuron derivation. Electronic supplementary material The online version of this article (doi:10.1186/s12929-016-0251-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mingming Li
- Faculty of Dentistry, National University of Singapore, Kent Ridge, Singapore
| | - Yu Zou
- Faculty of Dentistry, National University of Singapore, Kent Ridge, Singapore
| | - Qiqi Lu
- Faculty of Dentistry, National University of Singapore, Kent Ridge, Singapore
| | - Ning Tang
- Department of Pharmacology, Yong Loo Lin School of Medicine, The National University of Singapore, Kent Ridge, Singapore.,Neurobiology and Ageing Programme, Life Sciences Institute of the National University of Singapore, Kent Ridge, Singapore.,Singapore Institute for Neurotechnology (SINAPSE), The National University of Singapore, Kent Ridge, Singapore
| | - Alexis Heng
- Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong
| | - Intekhab Islam
- Faculty of Dentistry, National University of Singapore, Kent Ridge, Singapore
| | - Huei Jinn Tong
- Faculty of Dentistry, National University of Singapore, Kent Ridge, Singapore
| | - Gavin S Dawe
- Department of Pharmacology, Yong Loo Lin School of Medicine, The National University of Singapore, Kent Ridge, Singapore.,Neurobiology and Ageing Programme, Life Sciences Institute of the National University of Singapore, Kent Ridge, Singapore.,Singapore Institute for Neurotechnology (SINAPSE), The National University of Singapore, Kent Ridge, Singapore.,National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), Kent Ridge, Singapore
| | - Tong Cao
- Faculty of Dentistry, National University of Singapore, Kent Ridge, Singapore. .,Tissue Engineering Program, Life Sciences Institute of the National University of Singapore, Kent Ridge, Singapore. .,National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), Kent Ridge, Singapore.
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8
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Row RH, Tsotras SR, Goto H, Martin BL. The zebrafish tailbud contains two independent populations of midline progenitor cells that maintain long-term germ layer plasticity and differentiate in response to local signaling cues. Development 2015; 143:244-54. [PMID: 26674311 DOI: 10.1242/dev.129015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 12/09/2015] [Indexed: 12/25/2022]
Abstract
Vertebrate body axis formation depends on a population of bipotential neuromesodermal cells along the posterior wall of the tailbud that make a germ layer decision after gastrulation to form spinal cord and mesoderm. Despite exhibiting germ layer plasticity, these cells never give rise to midline tissues of the notochord, floor plate and dorsal endoderm, raising the question of whether midline tissues also arise from basal posterior progenitors after gastrulation. We show in zebrafish that local posterior signals specify germ layer fate in two basal tailbud midline progenitor populations. Wnt signaling induces notochord within a population of notochord/floor plate bipotential cells through negative transcriptional regulation of sox2. Notch signaling, required for hypochord induction during gastrulation, continues to act in the tailbud to specify hypochord from a notochord/hypochord bipotential cell population. Our results lend strong support to a continuous allocation model of midline tissue formation in zebrafish, and provide an embryological basis for zebrafish and mouse bifurcated notochord phenotypes as well as the rare human congenital split notochord syndrome. We demonstrate developmental equivalency between the tailbud progenitor cell populations. Midline progenitors can be transfated from notochord to somite fate after gastrulation by ectopic expression of msgn1, a master regulator of paraxial mesoderm fate, or if transplanted into the bipotential progenitors that normally give rise to somites. Our results indicate that the entire non-epidermal posterior body is derived from discrete, basal tailbud cell populations. These cells remain receptive to extracellular cues after gastrulation and continue to make basic germ layer decisions.
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Affiliation(s)
- Richard H Row
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Steve R Tsotras
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Hana Goto
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Benjamin L Martin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
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9
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Cordeiro IR, Lopes DV, Abreu JG, Carneiro K, Rossi MID, Brito JM. Chick embryo xenograft model reveals a novel perineural niche for human adipose-derived stromal cells. Biol Open 2015; 4:1180-93. [PMID: 26319582 PMCID: PMC4582113 DOI: 10.1242/bio.010256] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Human adipose-derived stromal cells (hADSC) are a heterogeneous cell population that contains adult multipotent stem cells. Although it is well established that hADSC have skeletal potential in vivo in adult organisms, in vitro assays suggest further differentiation capacity, such as into glia. Thus, we propose that grafting hADSC into the embryo can provide them with a much more instructive microenvironment, allowing the human cells to adopt diverse fates or niches. Here, hADSC spheroids were grafted into either the presumptive presomitic mesoderm or the first branchial arch (BA1) regions of chick embryos. Cells were identified without previous manipulations via human-specific Alu probes, which allows efficient long-term tracing of heterogeneous primary cultures. When grafted into the trunk, in contrast to previous studies, hADSC were not found in chondrogenic or osteogenic territories up to E8. Surprisingly, 82.5% of the hADSC were associated with HNK1+ tissues, such as peripheral nerves. Human skin fibroblasts showed a smaller tropism for nerves. In line with other studies, hADSC also adopted perivascular locations. When grafted into the presumptive BA1, 74.6% of the cells were in the outflow tract, the final goal of cardiac neural crest cells, and were also associated with peripheral nerves. This is the first study showing that hADSC could adopt a perineural niche in vivo and were able to recognize cues for neural crest cell migration of the host. Therefore, we propose that xenografts of human cells into chick embryos can reveal novel behaviors of heterogeneous cell populations, such as response to migration cues.
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Affiliation(s)
- Ingrid R Cordeiro
- Morphological Sciences Program, Biomedical Sciences Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Daiana V Lopes
- Morphological Sciences Program, Biomedical Sciences Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - José G Abreu
- Morphological Sciences Program, Biomedical Sciences Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Katia Carneiro
- Morphological Sciences Program, Biomedical Sciences Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Maria I D Rossi
- Morphological Sciences Program, Biomedical Sciences Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - José M Brito
- Morphological Sciences Program, Biomedical Sciences Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
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10
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FoxA4 favours notochord formation by inhibiting contiguous mesodermal fates and restricts anterior neural development in Xenopus embryos. PLoS One 2014; 9:e110559. [PMID: 25343614 PMCID: PMC4208771 DOI: 10.1371/journal.pone.0110559] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 09/24/2014] [Indexed: 11/19/2022] Open
Abstract
In vertebrates, the embryonic dorsal midline is a crucial signalling centre that patterns the surrounding tissues during development. Members of the FoxA subfamily of transcription factors are expressed in the structures that compose this centre. Foxa2 is essential for dorsal midline development in mammals, since knock-out mouse embryos lack a definitive node, notochord and floor plate. The related gene foxA4 is only present in amphibians. Expression begins in the blastula -chordin and -noggin expressing centre (BCNE) and is later restricted to the dorsal midline derivatives of the Spemann's organiser. It was suggested that the early functions of mammalian foxa2 are carried out by foxA4 in frogs, but functional experiments were needed to test this hypothesis. Here, we show that some important dorsal midline functions of mammalian foxa2 are exerted by foxA4 in Xenopus. We provide new evidence that the latter prevents the respecification of dorsal midline precursors towards contiguous fates, inhibiting prechordal and paraxial mesoderm development in favour of the notochord. In addition, we show that foxA4 is required for the correct regionalisation and maintenance of the central nervous system. FoxA4 participates in constraining the prospective rostral forebrain territory during neural specification and is necessary for the correct segregation of the most anterior ectodermal derivatives, such as the cement gland and the pituitary anlagen. Moreover, the early expression of foxA4 in the BCNE (which contains precursors of the whole forebrain and most of the midbrain and hindbrain) is directly required to restrict anterior neural development.
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11
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Alfaro AC, Roberts B, Kwong L, Bijlsma MF, Roelink H. Ptch2 mediates the Shh response in Ptch1-/- cells. Development 2014; 141:3331-9. [PMID: 25085974 DOI: 10.1242/dev.110056] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Hedgehog (Hh) signaling response is regulated by the interaction of three key components that include the sonic hedgehog (Shh) ligand, its receptor patched 1 (Ptch1) and the pathway activator smoothened (Smo). Under the prevailing model of Shh pathway activation, the binding of Shh to Ptch1 (the key Shh receptor) results in the release of Ptch1-mediated inhibition of Smo, leading to Smo activation and subsequent cell-autonomous activation of the Shh response. Consistent with this model, Ptch1(-/-) cells show a strong upregulation of the Shh response. Our finding that this response can be inhibited by the Shh-blocking antibody 5E1 indicates that the Shh response in Ptch1(-/-) cells remains ligand dependent. Furthermore, we find that Shh induces a strong response in Ptch1(-/-);Shh(-/-) cells, and that Ptch1(-/-) fibroblasts retain their ability to migrate towards Shh, demonstrating that Ptch1(-/-) cells remain sensitive to Shh. Expression of a dominant-negative Ptch1 mutant in the developing chick neural tube had no effect on Shh-mediated patterning, but expression of a dominant-negative form of patched 2 (Ptch2) caused an activation of the Shh response. This indicates that, at early developmental stages, Ptch2 functions to suppress Shh signaling. We found that Ptch1(-/-);Ptch2(-/-) cells cannot further activate the Shh response, demonstrating that Ptch2 mediates the response to Shh in the absence of Ptch1.
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Affiliation(s)
- Astrid C Alfaro
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Brock Roberts
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Lina Kwong
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Maarten F Bijlsma
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Henk Roelink
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
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12
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Al Oustah A, Danesin C, Khouri-Farah N, Farreny MA, Escalas N, Cochard P, Glise B, Soula C. Dynamics of sonic hedgehog signaling in the ventral spinal cord are controlled by intrinsic changes in source cells requiring sulfatase 1. Development 2014; 141:1392-403. [PMID: 24595292 DOI: 10.1242/dev.101717] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In the ventral spinal cord, generation of neuronal and glial cell subtypes is controlled by Sonic hedgehog (Shh). This morphogen contributes to cell diversity by regulating spatial and temporal sequences of gene expression during development. Here, we report that establishing Shh source cells is not sufficient to induce the high-threshold response required to specify sequential generation of ventral interneurons and oligodendroglial cells at the right time and place in zebrafish. Instead, we show that Shh-producing cells must repeatedly upregulate the secreted enzyme Sulfatase1 (Sulf1) at two critical time points of development to reach their full inductive capacity. We provide evidence that Sulf1 triggers Shh signaling activity to establish and, later on, modify the spatial arrangement of gene expression in ventral neural progenitors. We further present arguments in favor of Sulf1 controlling Shh temporal activity by stimulating production of active forms of Shh from its source. Our work, by pointing out the key role of Sulf1 in regulating Shh-dependent neural cell diversity, highlights a novel level of regulation, which involves temporal evolution of Shh source properties.
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Affiliation(s)
- Amir Al Oustah
- University of Toulouse, Center for Developmental Biology, UMR 5547 CNRS, 118 Route de Narbonne, 31062 Toulouse, France
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13
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Denham M, Bye C, Leung J, Conley BJ, Thompson LH, Dottori M. Glycogen synthase kinase 3β and activin/nodal inhibition in human embryonic stem cells induces a pre-neuroepithelial state that is required for specification to a floor plate cell lineage. Stem Cells 2013; 30:2400-11. [PMID: 22911885 PMCID: PMC3533765 DOI: 10.1002/stem.1204] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The floor plate is one of the major organizers of the developing nervous system through its secretion of sonic hedgehog (Shh). Although the floor plate is located within the neural tube, the derivation of the floor plate during development is still debatable and some studies suggest that floor plate cells are specified by Shh in a temporarily restricted window different to neuroepithelial cells. Using human embryonic stem cells (hESC) as a model of neurogenesis, we sought to determine how floor plate cells may be temporarily specified by SHH signaling during human embryogenesis. We found that inhibition of both GSK3β and activin/nodal pathways in hESC induces a cellular state of SOX2+/PAX6− expression, we describe as “pre-neuroepithelial.” Exposure of SHH during this pre-neuroepithelial period causes the expression of GLI transcription factors to function as activators and consequently upregulate expression of the floor plate marker, FOXA2, while also supressing PAX6 expression to inhibit neuroepithelial fate. FOXA2+ cells were able to efficiently generate mesencephalic dopaminergic neurons, a floor plate derivative. Overall, this study demonstrates a highly efficient system for generating floor plate cells from hESC and, most importantly, reveals that specification of floor plate cells is temporally dependent, whereby it occurs prior to the onset of PAX6 expression, within a pre-neuroepithelial stage. Stem Cells2012;30:2400–2411
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Affiliation(s)
- Mark Denham
- Centre for Neuroscience Research, Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia.
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14
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Bayly RD, Brown CY, Agarwala S. A novel role for FOXA2 and SHH in organizing midbrain signaling centers. Dev Biol 2012; 369:32-42. [PMID: 22750257 DOI: 10.1016/j.ydbio.2012.06.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 06/06/2012] [Accepted: 06/20/2012] [Indexed: 02/04/2023]
Abstract
The floor plate (FP) is a midline signaling center, known to direct ventral cell fates and axon guidance in the neural tube. The recent identification of midbrain FP as a source of dopaminergic neurons has renewed interest in its specification and organization, which remain poorly understood. In this study, we have examined the chick midbrain and spinal FP and show that both can be partitioned into medial (MFP) and lateral (LFP) subdivisions. Although Hedgehog (HH) signaling is necessary and sufficient for LFP specification, it is not sufficient for MFP induction. By contrast, the transcription factor FOXA2 can execute the full midbrain and spinal cord FP program via HH-independent and dependent mechanisms. Interestingly, although HH-independent FOXA2 activity is necessary and sufficient for inducing MFP-specific gene expression (e.g., LMX1B, BMP7), it cannot confer ventral identity to midline cells without also turning on Sonic hedgehog (SHH). We also note that the signaling centers of the midbrain, the FP, roof plate (RP) and the midbrain-hindbrain boundary (MHB) are physically contiguous, with each expressing LMX1B and BMP7. Possibly as a result, SHH or FOXA2 misexpression can transform the MHB into FP and also suppress RP induction. Conversely, HH or FOXA2 knockdown expands the endogenous RP and transforms the MFP into a RP and/or MHB fate. Finally, combined HH blockade and FOXA2 misexpression in ventral midbrain induces LMX1B expression, which triggers the specification of the RP, rather than the MFP. Thus we identify HH-independent and dependent roles for FOXA2 in specifying the FP. In addition, we elucidate for the first time, a novel role for SHH in determining whether a midbrain signaling center will become the FP, MHB or RP.
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Affiliation(s)
- Roy D Bayly
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712-0248, USA
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15
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Stanic K, Montecinos H, Caprile T. Subdivisions of chick diencephalic roof plate: implication in the formation of the posterior commissure. Dev Dyn 2011; 239:2584-93. [PMID: 20730872 DOI: 10.1002/dvdy.22387] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The subcommissural organ (SCO) is a roof plate differentiation located in the caudal diencephalon under the posterior commissure (PC). A role for SCO and its secretory product, SCO-spondin, in the formation of the PC has been proposed. Here, we provide immunohistochemical evidence to suggest that SCO is anatomically divided in a bilateral region positive for SCO-spondin that surrounds a negative medial region. Remarkably, axons contacting the lateral region are highly fasciculated, in sharp contrast with the defasciculated axons of the medial region. In addition, lateral axon fascicles run toward the midline inside of tunnels limited by the basal prolongations of SCO cells and extracellular SCO-spondin. Our in vitro data in collagen gel matrices show that SCO-spondin induces axonal growth and fasciculation of pretectal explants. Together, our findings support the idea that SCO-spondin participates in the guidance and fasciculation of axons of the PC.
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Affiliation(s)
- Karen Stanic
- Department of Cell Biology, University of Concepción, Chile
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16
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Peyrot SM, Wallingford JB, Harland RM. A revised model of Xenopus dorsal midline development: differential and separable requirements for Notch and Shh signaling. Dev Biol 2011; 352:254-66. [PMID: 21276789 DOI: 10.1016/j.ydbio.2011.01.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 01/18/2011] [Accepted: 01/19/2011] [Indexed: 11/30/2022]
Abstract
The development of the vertebrate dorsal midline (floor plate, notochord, and hypochord) has been an area of classical research and debate. Previous studies in vertebrates have led to contrasting models for the roles of Shh and Notch signaling in specification of the floor plate, by late inductive or early allocation mechanisms, respectively. Here, we show that Notch signaling plays an integral role in cell fate decisions in the dorsal midline of Xenopus laevis, similar to that observed in zebrafish and chick. Notch signaling promotes floor plate and hypochord fates over notochord, but has variable effects on Shh expression in the midline. In contrast to previous reports in frog, we find that Shh signaling is not required for floor plate vs. notochord decisions and plays a minor role in floor plate specification, where it acts in parallel to Notch signaling. As in zebrafish, Shh signaling is required for specification of the lateral floor plate in the frog. We also find that the medial floor plate in Xenopus comprises two distinct populations of cells, each dependent upon different signals for its specification. Using expression analysis of several midline markers, and dissection of functional relationships, we propose a revised allocation mechanism of dorsal midline specification in Xenopus. Our model is distinct from those proposed to date, and may serve as a guide for future studies in frog and other vertebrate organisms.
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Affiliation(s)
- Sara M Peyrot
- Dept of Molecular and Cell Biology and Center for Integrative Genomics, University of California, Berkeley, CA 94720, USA
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Lek M, Dias JM, Marklund U, Uhde CW, Kurdija S, Lei Q, Sussel L, Rubenstein JL, Matise MP, Arnold HH, Jessell TM, Ericson J. A homeodomain feedback circuit underlies step-function interpretation of a Shh morphogen gradient during ventral neural patterning. Development 2010; 137:4051-60. [PMID: 21062862 DOI: 10.1242/dev.054288] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The deployment of morphogen gradients is a core strategy to establish cell diversity in developing tissues, but little is known about how small differences in the concentration of extracellular signals are translated into robust patterning output in responding cells. We have examined the activity of homeodomain proteins, which are presumed to operate downstream of graded Shh signaling in neural patterning, and describe a feedback circuit between the Shh pathway and homeodomain transcription factors that establishes non-graded regulation of Shh signaling activity. Nkx2 proteins intrinsically strengthen Shh responses in a feed-forward amplification and are required for ventral floor plate and p3 progenitor fates. Conversely, Pax6 has an opposing function to antagonize Shh signaling, which provides intrinsic resistance to Shh responses and is important to constrain the inductive capacity of the Shh gradient over time. Our data further suggest that patterning of floor plate cells and p3 progenitors is gated by a temporal switch in neuronal potential, rather than by different Shh concentrations. These data establish that dynamic, non-graded changes in responding cells are essential for Shh morphogen interpretation, and provide a rationale to explain mechanistically the phenomenon of cellular memory of morphogen exposure.
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Affiliation(s)
- Madelen Lek
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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18
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Ribes V, Balaskas N, Sasai N, Cruz C, Dessaud E, Cayuso J, Tozer S, Yang LL, Novitch B, Marti E, Briscoe J. Distinct Sonic Hedgehog signaling dynamics specify floor plate and ventral neuronal progenitors in the vertebrate neural tube. Genes Dev 2010; 24:1186-200. [PMID: 20516201 PMCID: PMC2878655 DOI: 10.1101/gad.559910] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 04/07/2010] [Indexed: 12/14/2022]
Abstract
The secreted ligand Sonic Hedgehog (Shh) organizes the pattern of cellular differentiation in the ventral neural tube. For the five neuronal subtypes, increasing levels and durations of Shh signaling direct progenitors to progressively more ventral identities. Here we demonstrate that this mode of action is not applicable to the generation of the most ventral cell type, the nonneuronal floor plate (FP). In chick and mouse embryos, FP specification involves a biphasic response to Shh signaling that controls the dynamic expression of key transcription factors. During gastrulation and early somitogenesis, FP induction depends on high levels of Shh signaling. Subsequently, however, prospective FP cells become refractory to Shh signaling, and this is a prerequisite for the elaboration of their identity. This prompts a revision to the model of graded Shh signaling in the neural tube, and provides insight into how the dynamics of morphogen signaling are deployed to extend the patterning capacity of a single ligand. In addition, we provide evidence supporting a common scheme for FP specification by Shh signaling that reconciles mechanisms of FP development in teleosts and amniotes.
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Affiliation(s)
- Vanessa Ribes
- Developmental Neurobiology, Medical Research Council-National Institute for Medical Research, London NW7 1AA, United Kingdom
| | - Nikolaos Balaskas
- Developmental Neurobiology, Medical Research Council-National Institute for Medical Research, London NW7 1AA, United Kingdom
| | - Noriaki Sasai
- Developmental Neurobiology, Medical Research Council-National Institute for Medical Research, London NW7 1AA, United Kingdom
| | - Catarina Cruz
- Developmental Neurobiology, Medical Research Council-National Institute for Medical Research, London NW7 1AA, United Kingdom
| | - Eric Dessaud
- Developmental Neurobiology, Medical Research Council-National Institute for Medical Research, London NW7 1AA, United Kingdom
| | - Jordi Cayuso
- Instituto de Biología Molecular de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Barcelona 08028, Spain
| | - Samuel Tozer
- Developmental Neurobiology, Medical Research Council-National Institute for Medical Research, London NW7 1AA, United Kingdom
| | - Lin Lin Yang
- Department of Neurobiology, Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Ben Novitch
- Department of Neurobiology, Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Elisa Marti
- Instituto de Biología Molecular de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Barcelona 08028, Spain
| | - James Briscoe
- Developmental Neurobiology, Medical Research Council-National Institute for Medical Research, London NW7 1AA, United Kingdom
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Fasano CA, Chambers SM, Lee G, Tomishima MJ, Studer L. Efficient derivation of functional floor plate tissue from human embryonic stem cells. Cell Stem Cell 2010; 6:336-347. [PMID: 20362538 PMCID: PMC4336800 DOI: 10.1016/j.stem.2010.03.001] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 10/02/2009] [Accepted: 03/03/2010] [Indexed: 12/24/2022]
Abstract
The floor plate (FP) is a critical signaling center during neural development located along the ventral midline of the embryo. Little is known about human FP development because of the lack of tissue accessibility. Here we report the efficient derivation of human embryonic stem cell (hESC)-derived FP tissue capable of secreting Netrin-1 and SHH and patterning primary and hESC derived tissues. FP induction in hESCs is dependent on early SHH exposure and occurs at the expense of anterior neurectoderm (AN). Global gene expression and functional studies identify SHH-mediated inhibition of Dkk-1 as key factor in FP versus AN specification. hESC-derived FP tissue is shown to be of anterior SIX6+ character but is responsive to caudalizing factors suppressing SIX6 expression and inducing a shift in usage of region-specific SHH enhancers. These data define the early signals that drive human FP versus AN specification and determine regional identity in hESC-derived FP.
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Affiliation(s)
- Christopher A Fasano
- Developmental Biology Program, Sloan-Kettering Institute, 1275 York Ave, New York, NY 10065, USA; New York Neural Stem Cell Institute, Rensselaer, NY 12144, USA.
| | - Stuart M Chambers
- Developmental Biology Program, Sloan-Kettering Institute, 1275 York Ave, New York, NY 10065, USA
| | - Gabsang Lee
- Developmental Biology Program, Sloan-Kettering Institute, 1275 York Ave, New York, NY 10065, USA
| | - Mark J Tomishima
- SKI Stem Cell Research Facility, Sloan-Kettering Institute, 1275 York Ave, New York, NY 10065, USA
| | - Lorenz Studer
- Developmental Biology Program, Sloan-Kettering Institute, 1275 York Ave, New York, NY 10065, USA; Department of Neurosurgery, Sloan-Kettering Institute, 1275 York Ave, New York, NY 10065, USA.
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20
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Gray SD, Dale JK. Notch signalling regulates the contribution of progenitor cells from the chick Hensen's node to the floor plate and notochord. Development 2010; 137:561-8. [PMID: 20110321 DOI: 10.1242/dev.041608] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hensen's node of the chick embryo contains multipotent self-renewing progenitor cells that can contribute to either the floor plate or the notochord. Floor plate cells are a population of epithelial cells that lie at the ventral midline of the developing neural tube, whereas the notochord is a rod of axial mesoderm that lies directly beneath the floor plate. These two tissues serve as a source of a potent signalling morphogen, sonic hedgehog (Shh), which patterns the dorsoventral axis of the neural tube. We show, through both gain- and loss-of-function approaches, that Notch signalling promotes the contribution of chick axial progenitor cells to the floor plate and inhibits contribution to the notochord. Thus, we propose that Notch regulates the allocation of appropriate numbers of progenitor cells from Hensen's node of the chick embryo to the notochord and the floor plate.
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Affiliation(s)
- Shona D Gray
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, Scotland, UK
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Sánchez-Arrones L, Ferrán JL, Rodríguez-Gallardo L, Puelles L. Incipient forebrain boundaries traced by differential gene expression and fate mapping in the chick neural plate. Dev Biol 2009; 335:43-65. [PMID: 19699194 DOI: 10.1016/j.ydbio.2009.08.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 07/23/2009] [Accepted: 08/13/2009] [Indexed: 12/19/2022]
Abstract
We correlated available fate maps for the avian neural plate at stages HH4 and HH8 with the progress of local molecular specification, aiming to determine when the molecular specification maps of the primary longitudinal and transversal domains of the anterior forebrain agree with the fate mapped data. To this end, we examined selected gene expression patterns as they normally evolved in whole mounts and sections between HH4 and HH8 (or HH10/11 in some cases), performed novel fate-mapping experiments within the anterior forebrain at HH4 and examined the results at HH8, and correlated grafts with expression of selected gene markers. The data provided new details to the HH4 fate map, and disclosed some genes (e.g., Six3 and Ganf) whose expression domains initially are very extensive and subsequently retract rostralwards. Apart from anteroposterior dynamics, some genes soon became downregulated at the prospective forebrain floor plate, or allowed to identify an early roof plate domain (dorsoventral pattern). Peculiarities of the telencephalon (initial specification and differentiation of pallium versus subpallium) are contemplated. The basic anterior forebrain subdivisions seem to acquire correlated specification and fate mapping patterns around stage HH8.
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Affiliation(s)
- Luisa Sánchez-Arrones
- Department of Human Anatomy and Psychobiology, University of Murcia, School of Medicine, Murcia, E30071, Spain
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22
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Nishi Y, Ji H, Wong WH, McMahon AP, Vokes SA. Modeling the spatio-temporal network that drives patterning in the vertebrate central nervous system. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1789:299-305. [PMID: 19445894 DOI: 10.1016/j.bbagrm.2009.01.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 11/18/2008] [Accepted: 01/12/2009] [Indexed: 10/21/2022]
Abstract
In this review, we discuss the gene regulatory network underlying the patterning of the ventral neural tube during vertebrate embryogenesis. The neural tube is partitioned into domains of distinct cell fates by inductive signals along both anterior-posterior and dorsal-ventral axes. A defining feature of the dorsal-ventral patterning is the graded distribution of Sonic hedgehog (Shh), which acts as a morphogen to specify several classes of ventral neurons in a concentration-dependent fashion. These inductive signals translate into patterned expressions of transcription factors that define different neural progenitor subtypes. Progenitor boundaries are sharpened by repressive interactions between these transcription factors. The progenitor-expressed transcription factors induce another set of transcription factors that are thought to contribute to neural identities in post-mitotic neural precursors. Thus, the gene regulatory network of the ventral neural tube patterning is characterized by hierarchical expression [inductive signal-->progenitor specifying factors (mitotic)--> precursor specifying factors (post mitotic)--> differentiated neural markers] and cross-repression between progenitor-expressed regulatory factors. Although a number of transcriptional regulators have been identified at each hierarchical level, their precise regulatory relationships are not clear. Here we discuss approaches aimed at clarifying and extending our understanding of the formation and propagation of this network.
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Affiliation(s)
- Yuichi Nishi
- Department of Molecular and Cellular Biology, Harvard University , Cambridge, MA 02138, USA
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23
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Abstract
Hedgehog (HH) signalling is involved in the development of numerous embryonic tissues. In humans,germline mutations in hedgehog pathway components cause congenital malformations and somatic mutations are associated with cancers. The basic framework of the HH pathway was elucidated in the fruitfly, Drosophila melanogaster, and this pathway is largely conserved in vertebrates, although some important differences have been noted. The current paradigm of the "canonical" pathway views HH signalling as a series of repressive interactions which culminates in GLI-mediated transcriptional regulation of a variety of cellular processes. Definitions of "non-canonical" signalling stem from examples where the response to HH morphogen deviates from this paradigm and, according to current reports, three general scenarios of noncanonical HH signalling can be defined: (1) Signalling that involves HH pathway components but which is independent of GLI-mediated transcription; (2) Direct interaction of HH signalling components with components of other molecular pathways; and (3) "Non-contiguous" or "atypical" interaction of core HH pathway components with one another. Currently, the evidence supporting non-canonical HH signalling is not conclusive. However, Sonic hedgehog (SHH) has been shown to regulate cell migration and axon guidance in several contexts, and some of these processes are independent of downstream components of the HH pathway, and presumably the transcriptional response to morphogen. Furthermore, biochemical studies have shown that the HH receptor, PTCH1, can directly interact both with Cyclin B1 and caspases, to inhibit cell proliferation and to promote apoptosis, respectively, and that these functions are inhibited in the presence of morphogen. Genetic analysis of orthologues of the HH pathway in nematode worms further supports the notion that PTCH1-related molecules can function independently of other components of the canonical HH pathway, and the phenotypes of mice with point mutations in the Ptch1 gene offer clues as to the processes that non-canonical HH signalling might regulate. While none of these evidences are conclusive,collectively they point to the existence of added complexity in the HH pathway in the form of non-canonical pathways. A major difficulty in studying this problem is that canonical and non-canonical pathways are likely to act in parallel, and so in many situations it will not be possible to implicate non-canonical responses in certain cellular processes simply by excluding a role for the canonical pathway-directed analyses of non-canonical HH signalling are therefore necessary. The aim of this review is to present the cumulative evidence supporting non-canonical HH signalling, with the hope of promoting further enquiry into this area.
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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.
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Affiliation(s)
- Irene de Almeida
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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27
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Schäfer M, Kinzel D, Winkler C. Discontinuous organization and specification of the lateral floor plate in zebrafish. Dev Biol 2006; 301:117-29. [PMID: 17045256 DOI: 10.1016/j.ydbio.2006.09.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 09/09/2006] [Accepted: 09/11/2006] [Indexed: 01/06/2023]
Abstract
The floor plate is a signaling center in the ventral neural tube of vertebrates with important functions during neural patterning and axon guidance. It is composed of a centrally located medial floor plate (MFP) and a bilaterally positioned lateral floor plate (LFP). While the role of the MFP as source of signaling molecules like, e.g., Sonic Hedgehog (Shh) is well understood, the exact organization and function of the LFP are currently unclear. Based on expression analyses, the one cell wide LFP in zebrafish has been postulated to be a homogenous structure. We instead show that the zebrafish trunk LFP is discontinuously arranged. Single LFP cells alternate with p3 neuronal precursor cells, which develop V3 interneurons along the anteroposterior (AP) axis. Our mutant analyses indicate that both, formation of LFP and p3 cells require Delta-Notch signaling. Importantly, however, the two cell types are differentially regulated by Hedgehog (HH) and Nkx2.2 activities. This implicates a novel mechanism of neural tube patterning, in which distinct cell populations within one domain of the ventral neural tube are differently specified along the AP axis. We conclude that different levels of HH and Nkx2.2 activities are responsible for the alternating appearance of LFP and p3 neuronal progenitor cells in the zebrafish ventral neural tube.
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Affiliation(s)
- Matthias Schäfer
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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28
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Brito JM, Teillet MA, Le Douarin NM. An early role for sonic hedgehog from foregut endoderm in jaw development: ensuring neural crest cell survival. Proc Natl Acad Sci U S A 2006; 103:11607-12. [PMID: 16868080 PMCID: PMC1544217 DOI: 10.1073/pnas.0604751103] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have investigated the role of Sonic hedgehog (Shh) in the development of facial structures by depriving chicken embryos of the most anterior sources of this morphogen, including the prechordal plate and the anterior ventral endoderm of the foregut, before the onset of neural crest cell (NCC) migration to the first branchial arch (BA1). The entire forehead, including the foregut endoderm, was removed at 5- to 10-somite stage (ss), which led to the absence of the lower jaw when the operation was performed before 7-ss. If the embryos were deprived of their forehead at 8- to 10-ss, they were later on endowed with a lower beak. In embryos that were operated on early, the NCCs migrated normally to BA1 but were subjected to massive apoptosis a few hours later. Cell death did not occur when forehead excision was performed at a later stage. In this case, onward expression of Shh in the ventral foregut endoderm extended caudally over the excision limit, and we hypothesized that absence of Shh production by the endoderm in embryos that were operated on early could be responsible for the NCC apoptosis and the failure of BA1 development. We thus provided exogenous Shh to the embryos that were operated on before 7-ss. In this case, the development of the lower jaw was rescued. Therefore, Shh derived from the ventral foregut endoderm ensures the survival of NCCs at a critical stage of BA1 development.
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Affiliation(s)
- José M. Brito
- *Laboratoire de Développement, Evolution et Plasticité du Système Nerveux, Unité Propre de Recherche 2197, Centre National de la Recherche Scientifique, Institut de Neurobiologie Alfred Fessard, F-91198 Gif-sur-Yvette, France; and
| | - Marie-Aimée Teillet
- Laboratoire de Biologie du Développement, Unité Mixte de Recherche 7622, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie, F-75252 Paris, France
| | - Nicole M. Le Douarin
- *Laboratoire de Développement, Evolution et Plasticité du Système Nerveux, Unité Propre de Recherche 2197, Centre National de la Recherche Scientifique, Institut de Neurobiologie Alfred Fessard, F-91198 Gif-sur-Yvette, France; and
- To whom correspondence should be addressed. E-mail:
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29
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Callebaut M, Van Nueten E, Van Passel H, Harrisson F, Bortier H. Early steps in neural development. J Morphol 2006; 267:793-802. [PMID: 16572410 DOI: 10.1002/jmor.10436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We studied early neurulation events in vitro by transplanting quail Hensen's node, central prenodal regions (before the nodus as such develops), or upper layer parts of it on the not yet definitively committed upper layer of chicken anti-sickle regions (of unincubated blastoderms), eventually associated with central blastoderm fragments. We could demonstrate by this quail-chicken chimera technique that after the appearance of a pronounced thickening of the chicken upper layer by the early inductive effect of neighboring endophyll, a floor plate forms by insertion of Hensen's node-derived quail cells into the median part of the groove. This favors, at an early stage, the floor plate "allocation" model that postulates a common origin for notochord and median floor plate cells from the vertebrate's secondary major organizer (Hensen's node in this case). A comparison is made with results obtained after transplantation of similar Hensen's nodes in isolated chicken endophyll walls or with previously obtained results after the use of the grafting procedure in the endophyll walls of whole chicken blastoderms.
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Affiliation(s)
- Marc Callebaut
- University of Antwerp, Laboratory of Human Anatomy and Embryology, B-2020 Antwerpen, Belgium.
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Agarwala S, Aglyamova GV, Marma AK, Fallon JF, Ragsdale CW. Differential susceptibility of midbrain and spinal cord patterning to floor plate defects in the talpid2 mutant. Dev Biol 2005; 288:206-20. [PMID: 16246323 DOI: 10.1016/j.ydbio.2005.09.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Revised: 09/13/2005] [Accepted: 09/14/2005] [Indexed: 01/05/2023]
Abstract
The chick talpid2 mutant displays polydactylous digits attributed to defects of the Hedgehog (HH) signaling pathway. We examined the talpid2 neural tube and show that patterning defects in the spinal cord and the midbrain are distinct from each other and from the limb. Unlike the Sonic Hedgehog (SHH) source in the limb, the SHH-rich floor plate (FP) is reduced in the talpid2 midbrain. This is accompanied by a severe depletion of medial cell populations that encounter high concentrations of SHH, an expansion of lateral cell populations that experience low concentrations of SHH and a broad deregulation of HH's principal effectors (PTC1, GLI1, GLI2, GLI3). Together with the failure of SHH misexpression to rescue the talpid2 phenotype, these results suggest that talpid2 is likely to have a tissue-autonomous, bidirectional (positive and negative) role in HH signaling that cannot be attributed to the altered expression of several newly cloned HH pathway genes (SUFU, DZIP1, DISP1, BTRC). Strikingly, FP defects in the spinal cord are accompanied by relatively normal patterning in the talpid2 mutant. We propose that this differential FP dependence may be due to the prolonged apposition of the notochord to the spinal cord, but not the midbrain during development.
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Affiliation(s)
- Seema Agarwala
- Section of Neurobiology, University of Texas at Austin, Austin, TX 78712-0248, USA.
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31
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Abstract
The notion of "morphogens" is an important one in developmental biology. By definition, a morphogen is a molecule that emanates from a specific set of cells that is present in a concentration gradient and that specifies the fate of each cell along this gradient. The strongest candidate morphogens are members of the transforming growth factor-beta (TGF-beta), Hedgehog (Hh), and Wnt families. While these morphogens have been extensively described as differentiation inducers, some reports also suggest their possible involvement in cell death and cell survival. It is frequently speculated that the cell death induction that is found associated with experimental removal of morphogens is the manifestation of abnormal differentiation signals. However, several recent reports have raised controversy about this death by default, suggesting that cell death regulation is an active process for shaping tissues and organs. In this review, we will present morphogens, with a specific emphasis on Sonic Hedgehog, a mammalian member of the Hh family, not as a positive regulators of cell differentiation but as key regulators of cell survival.
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Affiliation(s)
- Patrick Mehlen
- Laboratoire Apoptose, Cancer et Développement, Equipe labelisée La Ligue, CNRS FRE2870, Centre Léon Bérard, 69008 Lyon, France.
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32
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Abstract
One of the key organizers in the CNS is the floor plate - a group of cells that is responsible for instructing neural cells to acquire distinctive fates, and that has an important role in establishing the elaborate neuronal networks that underlie the function of the brain and spinal cord. In recent years, considerable controversy has arisen over the mechanism by which floor plate cells form. Here, we describe recent evidence that indicates that discrete populations of floor plate cells, with characteristic molecular properties, form in different regions of the neuraxis, and we discuss data that imply that the mode of floor plate induction varies along the anteroposterior axis.
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Affiliation(s)
- Marysia Placzek
- Centre for Developmental and Biomedical Genetics, Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK.
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33
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Schäfer M, Kinzel D, Neuner C, Schartl M, Volff JN, Winkler C. Hedgehog and retinoid signalling confines nkx2.2b expression to the lateral floor plate of the zebrafish trunk. Mech Dev 2005; 122:43-56. [PMID: 15582776 DOI: 10.1016/j.mod.2004.09.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 09/07/2004] [Accepted: 09/09/2004] [Indexed: 10/26/2022]
Abstract
The ventral neural tube of vertebrates consists of distinct neural progenitor domains positioned along the dorsoventral (DV) axis that develop different types of moto- and interneurons. Several signalling molecules, most notably Sonic Hedgehog (Shh), retinoic acid (RA) and fibroblast growth factor (FGF) have been implicated in the generation of these domains. Shh is secreted from the floor plate, the ventral most neural tube structure that consists of the medial (MFP) and the lateral floor plate (LFP). While the MFP is well characterized, organization and function of the LFP remains unclear. Here, we describe the novel homeobox gene nkx2.2b that is strongly expressed in the trunk LFP of zebrafish and thus represents a unique marker for the characterization of LFP formation and the identification of LFP deficient mutants. nkx2.2b and its paralog nkx2.2a (formerly known as nk2.2 and nkx2.2) arose by gene duplication in zebrafish. Both duplicates show significant differences in their expression patterns. For example, while prominent nkx2.2a expression has been described in the ventral brain [Barth, K.A., Wilson, S.W., 1995. Expression of zebrafish nk2.2 is influenced by sonic hedgehog/vertebrate hedgehog-1 and demarcates a zone of neuronal differentiation in the embryonic forebrain. Development 121, 1755-1768], hardly any expression can be found in the trunk LFP, which is in contrast to nkx2.2b. Overexpression, mutant and inhibitor analyses show that nkx2.2b expression in the LFP is up-regulated by Shh, but repressed by retinoids and ectopic islet-1 (isl1) expression. In contrast to previously described zebrafish trunk LFP markers, like e.g. tal2 or foxa2, nkx2.2b is exclusively expressed in the LFP. Thus, it represents a unique tool to analyse the mechanisms of ventral neural tube patterning in zebrafish.
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Affiliation(s)
- Matthias Schäfer
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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Haigo SL, Harland RM, Wallingford JB. A family of Xenopus BTB-Kelch repeat proteins related to ENC-1: new markers for early events in floorplate and placode development. Gene Expr Patterns 2003; 3:669-74. [PMID: 12972004 DOI: 10.1016/s1567-133x(03)00095-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the expression of a family of Xenopus genes encoding BTB-Kelch repeat proteins related to mouse ENC-1. Xenopus ENC-related-1 (Xencr-1) is expressed throughout the dorsal midline in dorsal endoderm, notochord, and deep neuroectoderm cells during early neurula stages. Later, Xencr-1 expression is downregulated in the notochord in an anterior-to-posterior progression but is maintained in the floorplate and dorsal endoderm. Xencr-3 is expressed strongly in several cranial placodes during the early neurula stages, placing it among the earliest molecular markers of placode precursor populations.
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Affiliation(s)
- Saori L Haigo
- Department of Molecular and Cell Biology, 401 Barker Hall #3204, University of California, Berkeley, CA 94720-3204, USA
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Abstract
The ability of an animal to carry out its normal behavioral repertoire requires generation of an enormous diversity of neurons and glia. The relative simplicity of the spinal cord makes this an especially attractive part of the nervous system for addressing questions about the development of vertebrate neural specification and function. The last decade has witnessed an explosion in our understanding of spinal cord development and the functional interactions among spinal cord neurons and glia. Cellular, genetic, molecular, physiological and behavioral studies in zebrafish have all been important in providing insights into questions that remained unanswered by studies from other vertebrate model organisms. This is the case because many zebrafish spinal neurons can be individually identified and followed over time in living embryos and larvae. In this review, we discuss what is currently known about the cellular, genetic and molecular mechanisms involved in specifying distinct cell types in the zebrafish spinal cord and how these cells establish the functional circuitry that mediates particular behaviors. We start by describing the early signals and morphogenetic movements that form the nervous system, and in particular, the spinal cord. We then provide an overview of the cell types within the spinal cord and describe how they are specified and patterned. We begin ventrally with floor plate and proceed dorsally, through motoneurons and oligodendrocytes, interneurons, astrocytes and radial glia, spinal sensory neurons and neural crest. We next describe axon pathfinding of spinal neurons. Finally, we discuss the roles of particular spinal cord neurons in specific behaviors.
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Affiliation(s)
- Katharine E Lewis
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR 97403, USA.
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