1
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McNamara HM, Jia BZ, Guyer A, Parot VJ, Dobbs C, Schier AF, Cohen AE, Lord ND. Optogenetic control of Nodal signaling patterns. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.11.588875. [PMID: 38645239 PMCID: PMC11030342 DOI: 10.1101/2024.04.11.588875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
A crucial step in early embryogenesis is the establishment of spatial patterns of signaling activity. Tools to perturb morphogen signals with high resolution in space and time can help reveal how embryonic cells decode these signals to make appropriate fate decisions. Here, we present new optogenetic reagents and an experimental pipeline for creaHng designer Nodal signaling patterns in live zebrafish embryos. Nodal receptors were fused to the light-sensitive heterodimerizing pair Cry2/CIB1N, and the Type II receptor was sequestered to the cytosol. The improved optoNodal2 reagents eliminate dark activity and improve response kinetics, without sacrificing dynamic range. We adapted an ultra-widefield microscopy platform for parallel light patterning in up to 36 embryos and demonstrated precise spatial control over Nodal signaling activity and downstream gene expression. Patterned Nodal activation drove precisely controlled internalization of endodermal precursors. Further, we used patterned illumination to generate synthetic signaling patterns in Nodal signaling mutants, rescuing several characteristic developmental defects. This study establishes an experimental toolkit for systematic exploration of Nodal signaling patterns in live embryos.
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Affiliation(s)
| | - Bill Z. Jia
- Department of Systems Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Alison Guyer
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Vicente J. Parot
- Institute for Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Caleb Dobbs
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Adam E. Cohen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Nathan D. Lord
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, USA
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2
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Manning E, Placzek M. Organizing activities of axial mesoderm. Curr Top Dev Biol 2024; 157:83-123. [PMID: 38556460 DOI: 10.1016/bs.ctdb.2024.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
For almost a century, developmental biologists have appreciated that the ability of the embryonic organizer to induce and pattern the body plan is intertwined with its differentiation into axial mesoderm. Despite this, we still have a relatively poor understanding of the contribution of axial mesoderm to induction and patterning of different body regions, and the manner in which axial mesoderm-derived information is interpreted in tissues of changing competence. Here, with a particular focus on the nervous system, we review the evidence that axial mesoderm notochord and prechordal mesoderm/mesendoderm act as organizers, discuss how their influence extends through the different axes of the developing organism, and describe how the ability of axial mesoderm to direct morphogenesis impacts on its role as a local organizer.
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Affiliation(s)
- Elizabeth Manning
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom; Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Marysia Placzek
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom; Bateson Centre, University of Sheffield, Sheffield, United Kingdom; Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom.
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3
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Teague S, Primavera G, Chen B, Liu ZY, Yao L, Freeburne E, Khan H, Jo K, Johnson C, Heemskerk I. Time-integrated BMP signaling determines fate in a stem cell model for early human development. Nat Commun 2024; 15:1471. [PMID: 38368368 PMCID: PMC10874454 DOI: 10.1038/s41467-024-45719-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 02/02/2024] [Indexed: 02/19/2024] Open
Abstract
How paracrine signals are interpreted to yield multiple cell fate decisions in a dynamic context during human development in vivo and in vitro remains poorly understood. Here we report an automated tracking method to follow signaling histories linked to cell fate in large numbers of human pluripotent stem cells (hPSCs). Using an unbiased statistical approach, we discover that measured BMP signaling history correlates strongly with fate in individual cells. We find that BMP response in hPSCs varies more strongly in the duration of signaling than the level. However, both the level and duration of signaling activity control cell fate choices only by changing the time integral. Therefore, signaling duration and level are interchangeable in this context. In a stem cell model for patterning of the human embryo, we show that signaling histories predict the fate pattern and that the integral model correctly predicts changes in cell fate domains when signaling is perturbed. Our data suggest that mechanistically, BMP signaling is integrated by SOX2.
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Affiliation(s)
- Seth Teague
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Gillian Primavera
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Bohan Chen
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Zong-Yuan Liu
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - LiAng Yao
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Emily Freeburne
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Hina Khan
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Kyoung Jo
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Craig Johnson
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Idse Heemskerk
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA.
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA.
- Center for Cell Plasticity and Organ Design, University of Michigan Medical School, Ann Arbor, MI, USA.
- Department of Physics, University of Michigan, Ann Arbor, MI, USA.
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4
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Emig AA, Hansen M, Grimm S, Coarfa C, Lord ND, Williams MK. Temporal dynamics of BMP/Nodal ratio drive tissue-specific gastrulation morphogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.06.579243. [PMID: 38370754 PMCID: PMC10871350 DOI: 10.1101/2024.02.06.579243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Anteroposterior (AP) elongation of the vertebrate body plan is driven by convergence and extension (C&E) gastrulation movements in both the mesoderm and neuroectoderm, but how or whether molecular regulation of C&E differs between tissues remains an open question. Using a zebrafish explant model of AP axis extension, we show that C&E of the neuroectoderm and mesoderm can be uncoupled ex vivo, and that morphogenesis of individual tissues results from distinct morphogen signaling dynamics. Using precise temporal manipulation of BMP and Nodal signaling, we identify a critical developmental window during which high or low BMP/Nodal ratios induce neuroectoderm- or mesoderm-driven C&E, respectively. Increased BMP activity similarly enhances C&E specifically in the ectoderm of intact zebrafish gastrulae, highlighting the in vivo relevance of our findings. Together, these results demonstrate that temporal dynamics of BMP and Nodal morphogen signaling activate distinct morphogenetic programs governing C&E gastrulation movements within individual tissues.
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Affiliation(s)
- Alyssa A Emig
- Center for Precision Environmental Health and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX
| | - Megan Hansen
- Center for Precision Environmental Health and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX
| | - Sandra Grimm
- Center for Precision Environmental Health and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX
| | - Cristian Coarfa
- Center for Precision Environmental Health and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX
| | - Nathan D Lord
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA
| | - Margot Kossmann Williams
- Center for Precision Environmental Health and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX
- Previous address: Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
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5
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Richardson L, Wilcockson SG, Guglielmi L, Hill CS. Context-dependent TGFβ family signalling in cell fate regulation. Nat Rev Mol Cell Biol 2023; 24:876-894. [PMID: 37596501 DOI: 10.1038/s41580-023-00638-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2023] [Indexed: 08/20/2023]
Abstract
The transforming growth factor-β (TGFβ) family are a large group of evolutionarily conserved cytokines whose signalling modulates cell fate decision-making across varying cellular contexts at different stages of life. Here we discuss new findings in early embryos that reveal how, in contrast to our original understanding of morphogen interpretation, robust cell fate specification can originate from a noisy combination of signalling inputs and a broad range of signalling levels. We compare this evidence with novel findings on the roles of TGFβ family signalling in tissue maintenance and homeostasis during juvenile and adult life, spanning the skeletal, haemopoietic and immune systems. From these comparisons, it emerges that in contrast to robust developing systems, relatively small perturbations in TGFβ family signalling have detrimental effects at later stages in life, leading to aberrant cell fate specification and disease, for example in cancer or congenital disorders. Finally, we highlight novel strategies to target and amend dysfunction in signalling and discuss how gleaning knowledge from different fields of biology can help in the development of therapeutics for aberrant TGFβ family signalling in disease.
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Affiliation(s)
- Louise Richardson
- Developmental Signalling Laboratory, The Francis Crick Institute, London, UK
| | - Scott G Wilcockson
- Developmental Signalling Laboratory, The Francis Crick Institute, London, UK
| | - Luca Guglielmi
- Developmental Signalling Laboratory, The Francis Crick Institute, London, UK
- Division of Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Caroline S Hill
- Developmental Signalling Laboratory, The Francis Crick Institute, London, UK.
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6
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Cheng T, Xing YY, Liu C, Li YF, Huang Y, Liu X, Zhang YJ, Zhao GQ, Dong Y, Fu XX, Tian YM, Shu LP, Megason SG, Xu PF. Nodal coordinates the anterior-posterior patterning of germ layers and induces head formation in zebrafish explants. Cell Rep 2023; 42:112351. [PMID: 37018074 DOI: 10.1016/j.celrep.2023.112351] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 01/16/2023] [Accepted: 03/21/2023] [Indexed: 04/06/2023] Open
Abstract
Much progress has been made toward generating analogs of early embryos, such as gastruloids and embryoids, in vitro. However, methods for how to fully mimic the cell movements of gastrulation and coordinate germ-layer patterning to induce head formation are still lacking. Here, we show that a regional Nodal gradient applied to zebrafish animal pole explant can generate a structure that recapitulates the key cell movements of gastrulation. Using single-cell transcriptome and in situ hybridization analysis, we assess the dynamics of the cell fates and patterning of this structure. The mesendoderm differentiates into the anterior endoderm, prechordal plate, notochord, and tailbud-like cells along an anterior-posterior axis, and an anterior-posterior-patterned head-like structure (HLS) progressively forms during late gastrulation. Among 105 immediate Nodal targets, 14 genes contain axis-induction ability, and 5 of them induce a complete or partial head structure when overexpressed in the ventral side of zebrafish embryos.
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Affiliation(s)
- Tao Cheng
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yan-Yi Xing
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Zhejiang Provincial Key Laboratory of Genetic and Developmental Disorders, Hangzhou, Zhejiang, China
| | - Cong Liu
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yun-Fei Li
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Ying Huang
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xiang Liu
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Ying-Jie Zhang
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Guo-Qin Zhao
- Department of Immunology, Guizhou Medical University, Guiyang 550004, China
| | - Yang Dong
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xin-Xin Fu
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yi-Meng Tian
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Li-Ping Shu
- Department of Immunology, Guizhou Medical University, Guiyang 550004, China
| | - Sean G Megason
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
| | - Peng-Fei Xu
- Women's Hospital, Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
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7
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Thiemicke A, Neuert G. Rate thresholds in cell signaling have functional and phenotypic consequences in non-linear time-dependent environments. Front Cell Dev Biol 2023; 11:1124874. [PMID: 37025183 PMCID: PMC10072286 DOI: 10.3389/fcell.2023.1124874] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 03/08/2023] [Indexed: 04/08/2023] Open
Abstract
All cells employ signal transduction pathways to respond to physiologically relevant extracellular cytokines, stressors, nutrient levels, hormones, morphogens, and other stimuli that vary in concentration and rate in healthy and diseased states. A central unsolved fundamental question in cell signaling is whether and how cells sense and integrate information conveyed by changes in the rate of extracellular stimuli concentrations, in addition to the absolute difference in concentration. We propose that different environmental changes over time influence cell behavior in addition to different signaling molecules or different genetic backgrounds. However, most current biomedical research focuses on acute environmental changes and does not consider how cells respond to environments that change slowly over time. As an example of such environmental change, we review cell sensitivity to environmental rate changes, including the novel mechanism of rate threshold. A rate threshold is defined as a threshold in the rate of change in the environment in which a rate value below the threshold does not activate signaling and a rate value above the threshold leads to signal activation. We reviewed p38/Hog1 osmotic stress signaling in yeast, chemotaxis and stress response in bacteria, cyclic adenosine monophosphate signaling in Amoebae, growth factors signaling in mammalian cells, morphogen dynamics during development, temporal dynamics of glucose and insulin signaling, and spatio-temproral stressors in the kidney. These reviewed examples from the literature indicate that rate thresholds are widespread and an underappreciated fundamental property of cell signaling. Finally, by studying cells in non-linear environments, we outline future directions to understand cell physiology better in normal and pathophysiological conditions.
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Affiliation(s)
- Alexander Thiemicke
- Department of Molecular Physiology and Biophysics, School of Medicine, Vanderbilt University, Nashville, TN, United States
- Program in Chemical and Physical Biology, Vanderbilt University, Nashville, TN, United States
| | - Gregor Neuert
- Department of Molecular Physiology and Biophysics, School of Medicine, Vanderbilt University, Nashville, TN, United States
- Program in Chemical and Physical Biology, Vanderbilt University, Nashville, TN, United States
- Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, TN, United States
- *Correspondence: Gregor Neuert,
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8
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Economou AD, Guglielmi L, East P, Hill CS. Nodal signaling establishes a competency window for stochastic cell fate switching. Dev Cell 2022; 57:2604-2622.e5. [PMID: 36473458 PMCID: PMC7615190 DOI: 10.1016/j.devcel.2022.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 09/12/2022] [Accepted: 11/10/2022] [Indexed: 12/12/2022]
Abstract
Specification of the germ layers by Nodal signaling has long been regarded as an archetype of how graded morphogens induce different cell fates. However, this deterministic model cannot explain why only a subset of cells at the early zebrafish embryo margin adopt the endodermal fate, whereas their immediate neighbours, experiencing a similar signaling environment, become mesoderm. Combining pharmacology, quantitative imaging and single cell transcriptomics, we demonstrate that sustained Nodal signaling establishes a bipotential progenitor state from which cells can switch to an endodermal fate or differentiate into mesoderm. Switching is a random event, the likelihood of which is modulated by Fgf signaling. This inherently imprecise mechanism nevertheless leads to robust endoderm formation because of buffering at later stages. Thus, in contrast to previous deterministic models of morphogen action, Nodal signaling establishes a temporal window when cells are competent to undergo a stochastic cell fate switch, rather than determining fate itself.
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Affiliation(s)
- Andrew D Economou
- Developmental Signalling Laboratory, The Francis Crick Institute, London, UK
| | - Luca Guglielmi
- Developmental Signalling Laboratory, The Francis Crick Institute, London, UK
| | - Philip East
- Bioinformatics and Biostatistics Facility, The Francis Crick Institute, London, UK
| | - Caroline S Hill
- Developmental Signalling Laboratory, The Francis Crick Institute, London, UK.
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9
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Wang B, Zhao Q, Gong X, Wang C, Bai Y, Wang H, Zhou J, Rong X. Transmembrane anterior posterior transformation 1 regulates BMP signaling and modulates the protein stability of SMAD1/5. J Biol Chem 2022; 298:102684. [PMID: 36370851 PMCID: PMC9763856 DOI: 10.1016/j.jbc.2022.102684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 10/26/2022] [Accepted: 11/01/2022] [Indexed: 11/11/2022] Open
Abstract
The bone morphogenetic protein (BMP) signaling pathway plays pivotal roles in various biological processes during embryogenesis and adult homeostasis. Transmembrane anterior posterior transformation 1 (TAPT1) is an evolutionarily conserved protein involved in murine axial skeletal patterning. Genetic defects in TAPT1 result in complex lethal osteochondrodysplasia. However, the specific cellular activity of TAPT1 is not clear. Herein, we report that TAPT1 inhibits BMP signaling and destabilizes the SMAD1/5 protein by facilitating its interaction with SMURF1 E3 ubiquitin ligase, which leads to SMAD1/5 proteasomal degradation. In addition, we found that the activation of BMP signaling facilitates the redistribution of TAPT1 and promotes its association with SMAD1. TAPT1-deficient murine C2C12 myoblasts or C3H/10T1/2 mesenchymal stem cells exhibit elevated SMAD1/5/9 protein levels, which amplifies BMP activation, in turn leading to a boost in the transdifferentiation or differentiation processing of these distinct TAPT1-deficient cell lines changing into mature osteoblasts. Furthermore, the enhancing effect of TAPT1 deficiency on osteogenic differentiation of C3H/10T1/2 cells was observed in an in vivo ectopic bone formation model. Importantly, a subset of TAPT1 mutations identified in humans with lethal skeletal dysplasia exhibited gain-of-function activity on SMAD1 protein levels. Thus, this finding elucidates the role of TAPT1 in the regulation of SMAD1/5 protein stability for controlling BMP signaling.
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Affiliation(s)
- Bo Wang
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, Qingdao, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
| | - Qian Zhao
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, Qingdao, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
| | - Xiaoxia Gong
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, Qingdao, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
| | - Caixia Wang
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, Qingdao, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
| | - Yan Bai
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, Qingdao, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
| | - Hongying Wang
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, Key Laboratory of State Ethnic Affairs Commission for Biological Technology, College of Life Sciences, South-Central Minzu University, Wuhan, China
| | - Jianfeng Zhou
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, Qingdao, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China.
| | - Xiaozhi Rong
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, Qingdao, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China.
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10
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Abstract
Metazoan embryos develop from a single cell into three-dimensional structured organisms while groups of genetically identical cells attain specialized identities. Cells of the developing embryo both create and accurately interpret morphogen gradients to determine their positions and make specific decisions in response. Here, we first cover intellectual roots of morphogen and positional information concepts. Focusing on animal embryos, we then provide a review of current understanding on how morphogen gradients are established and how their spans are controlled. Lastly, we cover how gradients evolve in time and space during development, and how they encode information to control patterning. In sum, we provide a list of patterning principles for morphogen gradients and review recent advances in quantitative methodologies elucidating information provided by morphogens.
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Affiliation(s)
- M. Fethullah Simsek
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Ertuğrul M. Özbudak
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
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11
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Hill CS. Establishment and interpretation of NODAL and BMP signaling gradients in early vertebrate development. Curr Top Dev Biol 2022; 149:311-340. [PMID: 35606059 DOI: 10.1016/bs.ctdb.2021.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Transforming growth factor β (TGF-β) family ligands play crucial roles in orchestrating early embryonic development. Most significantly, two family members, NODAL and BMP form signaling gradients and indeed in fish, frogs and sea urchins these two opposing gradients are sufficient to organize a complete embryonic axis. This review focuses on how these gradients are established and interpreted during early vertebrate development. The review highlights key principles that are emerging, in particular the importance of signaling duration as well as ligand concentration in both gradient generation and their interpretation. Feedforward and feedback loops involving other signaling pathways are also essential for providing spatial and temporal information downstream of the NODAL and BMP signaling pathways. Finally, new data suggest the existence of buffering mechanisms, whereby early signaling defects can be readily corrected downstream later in development, suggesting that signaling gradients do not have to be as precise as previously thought.
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Affiliation(s)
- Caroline S Hill
- Developmental Signalling Laboratory, The Francis Crick Institute, London, United Kingdom.
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12
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Jones WD, Mullins MC. Cell signaling pathways controlling an axis organizing center in the zebrafish. Curr Top Dev Biol 2022; 150:149-209. [DOI: 10.1016/bs.ctdb.2022.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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13
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Wang X, Wang W, Wang Y, Chen J, Liu G, Zhang Y. Antibody-free profiling of transcription factor occupancy during early embryogenesis by FitCUT&RUN. Genome Res 2021; 32:378-388. [PMID: 34965941 PMCID: PMC8805719 DOI: 10.1101/gr.275837.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 12/22/2021] [Indexed: 11/24/2022]
Abstract
Key transcription factors (TFs) play critical roles in zygotic genome activation (ZGA) during early embryogenesis, while genome-wide occupancies of only a few factors have been profiled during ZGA due to the limitation of cell numbers or the lack of high-quality antibodies. Here, we present FitCUT&RUN, a modified CUT&RUN method, in which an Fc fragment of immunoglobulin G is used for tagging, to profile TF occupancy in an antibody-free manner and demonstrate its reliability and robustness using as few as five thousand K562 cells. We applied FitCUT&RUN to zebrafish undergoing embryogenesis to generate reliable occupancy profiles of three known activators of zebrafish ZGA: Nanog, Pou5f3 and Sox19b. By profiling the time-series occupancy of Nanog during zebrafish ZGA, we observed a clear trend toward a gradual increase in Nanog occupancy and found that Nanog occupancy prior to the major phase of ZGA is critical for the activation of a significant proportion of early transcribed genes. Our results further suggested that the sequential binding of Nanog may be controlled by replication timing and the presence of Nanog motifs.
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14
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Choe CP, Choi SY, Kee Y, Kim MJ, Kim SH, Lee Y, Park HC, Ro H. Transgenic fluorescent zebrafish lines that have revolutionized biomedical research. Lab Anim Res 2021; 37:26. [PMID: 34496973 PMCID: PMC8424172 DOI: 10.1186/s42826-021-00103-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/26/2021] [Indexed: 12/22/2022] Open
Abstract
Since its debut in the biomedical research fields in 1981, zebrafish have been used as a vertebrate model organism in more than 40,000 biomedical research studies. Especially useful are zebrafish lines expressing fluorescent proteins in a molecule, intracellular organelle, cell or tissue specific manner because they allow the visualization and tracking of molecules, intracellular organelles, cells or tissues of interest in real time and in vivo. In this review, we summarize representative transgenic fluorescent zebrafish lines that have revolutionized biomedical research on signal transduction, the craniofacial skeletal system, the hematopoietic system, the nervous system, the urogenital system, the digestive system and intracellular organelles.
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Affiliation(s)
- Chong Pyo Choe
- Division of Life Science, Gyeongsang National University, Jinju, 52828, Republic of Korea.,Division of Applied Life Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Seok-Yong Choi
- Department of Biomedical Sciences, Chonnam National University Medical School, Hwasun, 58128, Republic of Korea
| | - Yun Kee
- Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea.
| | - Min Jung Kim
- Department of Biological Sciences, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Seok-Hyung Kim
- Department of Marine Life Sciences and Fish Vaccine Research Center, Jeju National University, Jeju, 63243, Republic of Korea
| | - Yoonsung Lee
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan, 44919, Republic of Korea
| | - Hae-Chul Park
- Department of Biomedical Sciences, College of Medicine, Korea University, Ansan, 15355, Republic of Korea
| | - Hyunju Ro
- Department of Biological Sciences, College of Bioscience and Biotechnology, Chungnam National University, Daejeon, 34134, Republic of Korea
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15
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Song Y, Hyeon C. Cost-precision trade-off relation determines the optimal morphogen gradient for accurate biological pattern formation. eLife 2021; 10:70034. [PMID: 34402427 PMCID: PMC8457829 DOI: 10.7554/elife.70034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 08/13/2021] [Indexed: 01/05/2023] Open
Abstract
Spatial boundaries formed during animal development originate from the pre-patterning of tissues by signaling molecules, called morphogens. The accuracy of boundary location is limited by the fluctuations of morphogen concentration that thresholds the expression level of target gene. Producing more morphogen molecules, which gives rise to smaller relative fluctuations, would better serve to shape more precise target boundaries; however, it incurs more thermodynamic cost. In the classical diffusion-depletion model of morphogen profile formation, the morphogen molecules synthesized from a local source display an exponentially decaying concentration profile with a characteristic length λ. Our theory suggests that in order to attain a precise profile with the minimal cost, λ should be roughly half the distance to the target boundary position from the source. Remarkably, we find that the profiles of morphogens that pattern the Drosophila embryo and wing imaginal disk are formed with nearly optimal λ. Our finding underscores the cost-effectiveness of precise morphogen profile formation in Drosophila development.
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Affiliation(s)
- Yonghyun Song
- Korea Institute for Advanced Study, Seoul, Republic of Korea
| | - Changbong Hyeon
- Korea Institute for Advanced Study, Seoul, Republic of Korea
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16
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Lord ND, Carte AN, Abitua PB, Schier AF. The pattern of nodal morphogen signaling is shaped by co-receptor expression. eLife 2021; 10:e54894. [PMID: 34036935 PMCID: PMC8266389 DOI: 10.7554/elife.54894] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 05/26/2021] [Indexed: 12/13/2022] Open
Abstract
Embryos must communicate instructions to their constituent cells over long distances. These instructions are often encoded in the concentration of signals called morphogens. In the textbook view, morphogen molecules diffuse from a localized source to form a concentration gradient, and target cells adopt fates by measuring the local morphogen concentration. However, natural patterning systems often incorporate numerous co-factors and extensive signaling feedback, suggesting that embryos require additional mechanisms to generate signaling patterns. Here, we examine the mechanisms of signaling pattern formation for the mesendoderm inducer Nodal during zebrafish embryogenesis. We find that Nodal signaling activity spans a normal range in the absence of signaling feedback and relay, suggesting that diffusion is sufficient for Nodal gradient formation. We further show that the range of endogenous Nodal ligands is set by the EGF-CFC co-receptor Oep: in the absence of Oep, Nodal activity spreads to form a nearly uniform distribution throughout the embryo. In turn, increasing Oep levels sensitizes cells to Nodal ligands. We recapitulate these experimental results with a computational model in which Oep regulates the diffusive spread of Nodal ligands by setting the rate of capture by target cells. This model predicts, and we confirm in vivo, the surprising observation that a failure to replenish Oep transforms the Nodal signaling gradient into a travelling wave. These results reveal that patterns of Nodal morphogen signaling are shaped by co-receptor-mediated restriction of ligand spread and sensitization of responding cells.
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Affiliation(s)
- Nathan D Lord
- Department of Molecular and Cellular Biology, Harvard UniversityCambridgeUnited States
| | - Adam N Carte
- Department of Molecular and Cellular Biology, Harvard UniversityCambridgeUnited States
- Systems, Synthetic, and Quantitative Biology PhD Program, Harvard UniversityCambridgeUnited States
- Biozentrum, University of BaselBaselSwitzerland
| | - Philip B Abitua
- Department of Molecular and Cellular Biology, Harvard UniversityCambridgeUnited States
| | - Alexander F Schier
- Department of Molecular and Cellular Biology, Harvard UniversityCambridgeUnited States
- Biozentrum, University of BaselBaselSwitzerland
- Allen Discovery Center for Cell Lineage Tracing, University of WashingtonSeattleUnited States
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17
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Liu L, Warmflash A. Self-organized signaling in stem cell models of embryos. Stem Cell Reports 2021; 16:1065-1077. [PMID: 33979594 PMCID: PMC8185436 DOI: 10.1016/j.stemcr.2021.03.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/17/2021] [Accepted: 03/17/2021] [Indexed: 02/06/2023] Open
Abstract
Mammalian embryonic development is a complex process driven by self-organization. Understanding how a fertilized egg develops into an embryo composed of more than 200 cell types in precise spatial patterns remains one of the fundamental challenges in biology. Pluripotent stem cells have been used as in vitro models for investigating mammalian development, and represent promising building blocks for regenerative therapies. Recently, sophisticated stem cell-based models that recapitulate early embryonic fate patterning and morphogenesis have been developed. In this article, we review recent advances in stem cell models of embryos in particular focusing on signaling activities underpinning cell fate decisions in space and time.
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Affiliation(s)
- Lizhong Liu
- Department of Biosciences, Rice University, Houston, TX 77005, USA
| | - Aryeh Warmflash
- Department of Biosciences, Rice University, Houston, TX 77005, USA; Department of Bioengineering, Rice University, Houston, TX 77005, USA.
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18
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Integration of Nodal and BMP Signaling by Mutual Signaling Effector Antagonism. Cell Rep 2021; 31:107487. [PMID: 32268105 PMCID: PMC7166084 DOI: 10.1016/j.celrep.2020.03.051] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/26/2019] [Accepted: 03/16/2020] [Indexed: 01/08/2023] Open
Abstract
Opposing sources of bone morphogenetic protein (BMP) and Nodal signaling molecules are sufficient to induce the formation of a full axis in zebrafish embryos. To address how these signals orchestrate patterning, we transplant sources of fluorescently tagged Nodal and BMP into zebrafish embryos, robustly inducing the formation of secondary axes. Nodal and BMP signal non-cell-autonomously and form similar protein gradients in this context, but the signaling range of Nodal (pSmad2) is shorter than the BMP range (pSmad5). This yields a localized region of pSmad2 activity around the Nodal source, overlapping with a broad domain of pSmad5 activity across the embryo. Cell fates induced in various regions stereotypically correlate with pSmad2-to-pSmad5 ratios and can even be induced BMP- and Nodal-independently with different ratios of constitutively active Smad2 and Smad5. Strikingly, we find that Smad2 and Smad5 antagonize each other for specific cell fates, providing a mechanism for how cells integrate and discriminate between overlapping signals during development. Nodal induces pSmad at a shorter range than BMP due to slower activation kinetics Different ratios of active Smad2 and Smad5 can induce different embryonic structures Smad2 and Smad5 inhibit each other or act synergistically to induce specific cell fates
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19
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Figiel DM, Elsayed R, Nelson AC. Investigating the molecular guts of endoderm formation using zebrafish. Brief Funct Genomics 2021:elab013. [PMID: 33754635 DOI: 10.1093/bfgp/elab013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 01/27/2021] [Accepted: 02/19/2021] [Indexed: 02/07/2023] Open
Abstract
The vertebrate endoderm makes major contributions to the respiratory and gastrointestinal tracts and all associated organs. Zebrafish and humans share a high degree of genetic homology and strikingly similar endodermal organ systems. Combined with a multitude of experimental advantages, zebrafish are an attractive model organism to study endoderm development and disease. Recent functional genomics studies have shed considerable light on the gene regulatory programs governing early zebrafish endoderm development, while advances in biological and technological approaches stand to further revolutionize our ability to investigate endoderm formation, function and disease. Here, we discuss the present understanding of endoderm specification in zebrafish compared to other vertebrates, how current and emerging methods will allow refined and enhanced analysis of endoderm formation, and how integration with human data will allow modeling of the link between non-coding sequence variants and human disease.
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Affiliation(s)
- Daniela M Figiel
- Medical Research Council Doctoral Training Partnership in Interdisciplinary Biomedical Research at Warwick Medical School
| | - Randa Elsayed
- Medical Research Council Doctoral Training Partnership in Interdisciplinary Biomedical Research at Warwick Medical School
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20
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Greenfeld H, Lin J, Mullins MC. The BMP signaling gradient is interpreted through concentration thresholds in dorsal-ventral axial patterning. PLoS Biol 2021; 19:e3001059. [PMID: 33481775 PMCID: PMC7857602 DOI: 10.1371/journal.pbio.3001059] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/03/2021] [Accepted: 01/07/2021] [Indexed: 12/24/2022] Open
Abstract
Bone Morphogenetic Protein (BMP) patterns the dorsal–ventral (DV) embryonic axis in all vertebrates, but it is unknown how cells along the DV axis interpret and translate the gradient of BMP signaling into differential gene activation that will give rise to distinct cell fates. To determine the mechanism of BMP morphogen interpretation in the zebrafish gastrula, we identified 57 genes that are directly activated by BMP signaling. By using Seurat analysis of single-cell RNA sequencing (scRNA-seq) data, we found that these genes are expressed in at least 3 distinct DV domains of the embryo. We distinguished between 3 models of BMP signal interpretation in which cells activate distinct gene expression through interpretation of thresholds of (1) the BMP signaling gradient slope; (2) the BMP signal duration; or (3) the level of BMP signal activation. We tested these 3 models using quantitative measurements of phosphorylated Smad5 (pSmad5) and by examining the spatial relationship between BMP signaling and activation of different target genes at single-cell resolution across the embryo. We found that BMP signaling gradient slope or BMP exposure duration did not account for the differential target gene expression domains. Instead, we show that cells respond to 3 distinct levels of BMP signaling activity to activate and position target gene expression. Together, we demonstrate that distinct pSmad5 threshold levels activate spatially distinct target genes to pattern the DV axis. This study tested three models of how a BMP morphogen gradient is translated into differential gene activation that specifies distinct cell fates, finding that BMP signal concentration thresholds, not gradient shape or signal duration, position three distinct gene activation domains.
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Affiliation(s)
- Hannah Greenfeld
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
| | - Jerome Lin
- Institute for Biomedical Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
| | - Mary C. Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
- * E-mail:
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21
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Rogers KW, ElGamacy M, Jordan BM, Müller P. Optogenetic investigation of BMP target gene expression diversity. eLife 2020; 9:58641. [PMID: 33174840 PMCID: PMC7728441 DOI: 10.7554/elife.58641] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 11/10/2020] [Indexed: 12/15/2022] Open
Abstract
Signaling molecules activate distinct patterns of gene expression to coordinate embryogenesis, but how spatiotemporal expression diversity is generated is an open question. In zebrafish, a BMP signaling gradient patterns the dorsal-ventral axis. We systematically identified target genes responding to BMP and found that they have diverse spatiotemporal expression patterns. Transcriptional responses to optogenetically delivered high- and low-amplitude BMP signaling pulses indicate that spatiotemporal expression is not fully defined by different BMP signaling activation thresholds. Additionally, we observed negligible correlations between spatiotemporal expression and transcription kinetics for the majority of analyzed genes in response to BMP signaling pulses. In contrast, spatial differences between BMP target genes largely collapsed when FGF and Nodal signaling were inhibited. Our results suggest that, similar to other patterning systems, combinatorial signaling is likely to be a major driver of spatial diversity in BMP-dependent gene expression in zebrafish.
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Affiliation(s)
- Katherine W Rogers
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany
| | - Mohammad ElGamacy
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany.,Modeling Tumorigenesis Group, Translational Oncology Division, Eberhard Karls University Tübingen, Tübingen, Germany.,Heliopolis Biotechnology Ltd, London, United Kingdom
| | - Benjamin M Jordan
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States
| | - Patrick Müller
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany.,Modeling Tumorigenesis Group, Translational Oncology Division, Eberhard Karls University Tübingen, Tübingen, Germany
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22
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Kushawah G, Hernandez-Huertas L, Abugattas-Nuñez del Prado J, Martinez-Morales JR, DeVore ML, Hassan H, Moreno-Sanchez I, Tomas-Gallardo L, Diaz-Moscoso A, Monges DE, Guelfo JR, Theune WC, Brannan EO, Wang W, Corbin TJ, Moran AM, Sánchez Alvarado A, Málaga-Trillo E, Takacs CM, Bazzini AA, Moreno-Mateos MA. CRISPR-Cas13d Induces Efficient mRNA Knockdown in Animal Embryos. Dev Cell 2020; 54:805-817.e7. [DOI: 10.1016/j.devcel.2020.07.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 04/27/2020] [Accepted: 07/16/2020] [Indexed: 02/08/2023]
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23
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Fuentes R, Tajer B, Kobayashi M, Pelliccia JL, Langdon Y, Abrams EW, Mullins MC. The maternal coordinate system: Molecular-genetics of embryonic axis formation and patterning in the zebrafish. Curr Top Dev Biol 2020; 140:341-389. [PMID: 32591080 DOI: 10.1016/bs.ctdb.2020.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Axis specification of the zebrafish embryo begins during oogenesis and relies on proper formation of well-defined cytoplasmic domains within the oocyte. Upon fertilization, maternally-regulated cytoplasmic flow and repositioning of dorsal determinants establish the coordinate system that will build the structure and developmental body plan of the embryo. Failure of specific genes that regulate the embryonic coordinate system leads to catastrophic loss of body structures. Here, we review the genetic principles of axis formation and discuss how maternal factors orchestrate axis patterning during zebrafish early embryogenesis. We focus on the molecular identity and functional contribution of genes controlling critical aspects of oogenesis, egg activation, blastula, and gastrula stages. We examine how polarized cytoplasmic domains form in the oocyte, which set off downstream events such as animal-vegetal polarity and germ line development. After gametes interact and form the zygote, cytoplasmic segregation drives the animal-directed reorganization of maternal determinants through calcium- and cell cycle-dependent signals. We also summarize how maternal genes control dorsoventral, anterior-posterior, mesendodermal, and left-right cell fate specification and how signaling pathways pattern these axes and tissues during early development to instruct the three-dimensional body plan. Advances in reverse genetics and phenotyping approaches in the zebrafish model are revealing positional patterning signatures at the single-cell level, thus enhancing our understanding of genotype-phenotype interactions in axis formation. Our emphasis is on the genetic interrogation of novel and specific maternal regulatory mechanisms of axis specification in the zebrafish.
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Affiliation(s)
- Ricardo Fuentes
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
| | - Benjamin Tajer
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | - Manami Kobayashi
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | - Jose L Pelliccia
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | | | - Elliott W Abrams
- Department of Biology, Purchase College, State University of New York, Harrison, NY, United States
| | - Mary C Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States.
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24
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Abstract
Gastrulation is a critical early morphogenetic process of animal development, during which the three germ layers; mesoderm, endoderm and ectoderm, are rearranged by internalization movements. Concurrent epiboly movements spread and thin the germ layers while convergence and extension movements shape them into an anteroposteriorly elongated body with head, trunk, tail and organ rudiments. In zebrafish, gastrulation follows the proliferative and inductive events that establish the embryonic and extraembryonic tissues and the embryonic axis. Specification of these tissues and embryonic axes are controlled by the maternal gene products deposited in the egg. These early maternally controlled processes need to generate sufficient cell numbers and establish the embryonic polarity to ensure normal gastrulation. Subsequently, after activation of the zygotic genome, the zygotic gene products govern mesoderm and endoderm induction and germ layer patterning. Gastrulation is initiated during the maternal-to-zygotic transition, a process that entails both activation of the zygotic genome and downregulation of the maternal transcripts. Genomic studies indicate that gastrulation is largely controlled by the zygotic genome. Nonetheless, genetic studies that investigate the relative contributions of maternal and zygotic gene function by comparing zygotic, maternal and maternal zygotic mutant phenotypes, reveal significant contribution of maternal gene products, transcripts and/or proteins, that persist through gastrulation, to the control of gastrulation movements. Therefore, in zebrafish, the maternally expressed gene products not only set the stage for, but they also actively participate in gastrulation morphogenesis.
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Affiliation(s)
- Lilianna Solnica-Krezel
- Department of Developmental Biology and Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO, United States.
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25
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Williams ML, Solnica-Krezel L. Nodal and planar cell polarity signaling cooperate to regulate zebrafish convergence and extension gastrulation movements. eLife 2020; 9:54445. [PMID: 32319426 PMCID: PMC7250581 DOI: 10.7554/elife.54445] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 04/21/2020] [Indexed: 12/14/2022] Open
Abstract
During vertebrate gastrulation, convergence and extension (C and E) of the primary anteroposterior (AP) embryonic axis is driven by polarized mediolateral (ML) cell intercalations and is influenced by AP axial patterning. Nodal signaling is essential for patterning of the AP axis while planar cell polarity (PCP) signaling polarizes cells with respect to this axis, but how these two signaling systems interact during C and E is unclear. We find that the neuroectoderm of Nodal-deficient zebrafish gastrulae exhibits reduced C and E cell behaviors, which require Nodal signaling in both cell- and non-autonomous fashions. PCP signaling is partially active in Nodal-deficient embryos and its inhibition exacerbates their C and E defects. Within otherwise naïve zebrafish blastoderm explants, however, Nodal induces C and E in a largely PCP-dependent manner, arguing that Nodal acts both upstream of and in parallel with PCP during gastrulation to regulate embryonic axis extension cooperatively.
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Affiliation(s)
- Margot Lk Williams
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Lilianna Solnica-Krezel
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
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26
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Schauer A, Pinheiro D, Hauschild R, Heisenberg CP. Zebrafish embryonic explants undergo genetically encoded self-assembly. eLife 2020; 9:55190. [PMID: 32250246 PMCID: PMC7190352 DOI: 10.7554/elife.55190] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 04/05/2020] [Indexed: 12/20/2022] Open
Abstract
Embryonic stem cell cultures are thought to self-organize into embryoid bodies, able to undergo symmetry-breaking, germ layer specification and even morphogenesis. Yet, it is unclear how to reconcile this remarkable self-organization capacity with classical experiments demonstrating key roles for extrinsic biases by maternal factors and/or extraembryonic tissues in embryogenesis. Here, we show that zebrafish embryonic tissue explants, prepared prior to germ layer induction and lacking extraembryonic tissues, can specify all germ layers and form a seemingly complete mesendoderm anlage. Importantly, explant organization requires polarized inheritance of maternal factors from dorsal-marginal regions of the blastoderm. Moreover, induction of endoderm and head-mesoderm, which require peak Nodal-signaling levels, is highly variable in explants, reminiscent of embryos with reduced Nodal signals from the extraembryonic tissues. Together, these data suggest that zebrafish explants do not undergo bona fide self-organization, but rather display features of genetically encoded self-assembly, where intrinsic genetic programs control the emergence of order.
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27
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Camacho-Aguilar E, Warmflash A. Insights into mammalian morphogen dynamics from embryonic stem cell systems. Curr Top Dev Biol 2020; 137:279-305. [PMID: 32143746 PMCID: PMC7713707 DOI: 10.1016/bs.ctdb.2019.11.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Morphogens play an essential role in cell fate specification and patterning including in laying out the mammalian body plan during gastrulation. In vivo studies have shed light on the signaling pathways involved in this process and the phenotypes associated with their disruption, however, several important open questions remain regarding how morphogens function in space and time. Self-organized patterning systems based on embryonic stem cells have emerged as a powerful platform for beginning to address these questions that is complementary to in vivo approaches. Here we review recent progress in understanding morphogen signaling dynamics and patterning in early mammalian development by taking advantage of cutting-edge embryonic stem cell technology.
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Affiliation(s)
| | - Aryeh Warmflash
- Department of Biosciences, Rice University, Houston, TX, United States; Department of Bioengineering, Rice University, Houston, TX, United States.
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28
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29
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Pálfy M, Schulze G, Valen E, Vastenhouw NL. Chromatin accessibility established by Pou5f3, Sox19b and Nanog primes genes for activity during zebrafish genome activation. PLoS Genet 2020; 16:e1008546. [PMID: 31940339 PMCID: PMC6986763 DOI: 10.1371/journal.pgen.1008546] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 01/28/2020] [Accepted: 12/02/2019] [Indexed: 12/12/2022] Open
Abstract
In many organisms, early embryonic development is driven by maternally provided factors until the controlled onset of transcription during zygotic genome activation. The regulation of chromatin accessibility and its relationship to gene activity during this transition remain poorly understood. Here, we generated chromatin accessibility maps with ATAC-seq from genome activation until the onset of lineage specification. During this period, chromatin accessibility increases at regulatory elements. This increase is independent of RNA polymerase II-mediated transcription, with the exception of the hypertranscribed miR-430 locus. Instead, accessibility often precedes the transcription of associated genes. Loss of the maternal transcription factors Pou5f3, Sox19b, and Nanog, which are known to be required for zebrafish genome activation, results in decreased accessibility at regulatory elements. Importantly, the accessibility of regulatory regions, especially when established by Pou5f3, Sox19b and Nanog, is predictive for future transcription. Our results show that the maternally provided transcription factors Pou5f3, Sox19b, and Nanog open up chromatin and prime genes for activity during zygotic genome activation in zebrafish.
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Affiliation(s)
- Máté Pálfy
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Gunnar Schulze
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Eivind Valen
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
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30
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Čapek D, Müller P. Positional information and tissue scaling during development and regeneration. Development 2019; 146:146/24/dev177709. [PMID: 31862792 DOI: 10.1242/dev.177709] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In order to contribute to the appropriate tissues during development, cells need to know their position within the embryo. This positional information is conveyed by gradients of signaling molecules, termed morphogens, that are produced in specific regions of the embryo and induce concentration-dependent responses in target tissues. Positional information is remarkably robust, and embryos often develop with the correct proportions even if large parts of the embryo are removed. In this Review, we discuss classical embryological experiments and modern quantitative analyses that have led to mechanistic insights into how morphogen gradients adapt, scale and properly pattern differently sized domains. We analyze these experimental findings in the context of mathematical models and synthesize general principles that apply to multiple systems across species and developmental stages.
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Affiliation(s)
- Daniel Čapek
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, Max-Planck-Ring 9, 72076 Tübingen Germany
| | - Patrick Müller
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, Max-Planck-Ring 9, 72076 Tübingen Germany .,Modeling Tumorigenesis Group, Translational Oncology Division, Eberhard Karls University Tübingen, Otfried-Müller-Strasse 10, 72076 Tübingen Germany
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31
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Rogers KW, Müller P. Optogenetic approaches to investigate spatiotemporal signaling during development. Curr Top Dev Biol 2019; 137:37-77. [PMID: 32143750 DOI: 10.1016/bs.ctdb.2019.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Embryogenesis is coordinated by signaling pathways that pattern the developing organism. Many aspects of this process are not fully understood, including how signaling molecules spread through embryonic tissues, how signaling amplitude and dynamics are decoded, and how multiple signaling pathways cooperate to pattern the body plan. Optogenetic approaches can be used to address these questions by providing precise experimental control over a variety of biological processes. Here, we review how these strategies have provided new insights into developmental signaling and discuss how they could contribute to future investigations.
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Affiliation(s)
- Katherine W Rogers
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany
| | - Patrick Müller
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany; Modeling Tumorigenesis Group, Translational Oncology Division, Eberhard Karls University Tübingen, Tübingen, Germany.
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32
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Morgani SM, Hadjantonakis AK. Signaling regulation during gastrulation: Insights from mouse embryos and in vitro systems. Curr Top Dev Biol 2019; 137:391-431. [PMID: 32143751 DOI: 10.1016/bs.ctdb.2019.11.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Gastrulation is the process whereby cells exit pluripotency and concomitantly acquire and pattern distinct cell fates. This is driven by the convergence of WNT, BMP, Nodal and FGF signals, which are tightly spatially and temporally controlled, resulting in regional and stage-specific signaling environments. The combination, level and duration of signals that a cell is exposed to, according its position within the embryo and the developmental time window, dictates the fate it will adopt. The key pathways driving gastrulation exhibit complex interactions, which are difficult to disentangle in vivo due to the complexity of manipulating multiple signals in parallel with high spatiotemporal resolution. Thus, our current understanding of the signaling dynamics regulating gastrulation is limited. In vitro stem cell models have been established, which undergo organized cellular differentiation and patterning. These provide amenable, simplified, deconstructed and scalable models of gastrulation. While the foundation of our understanding of gastrulation stems from experiments in embryos, in vitro systems are now beginning to reveal the intricate details of signaling regulation. Here we discuss the current state of knowledge of the role, regulation and dynamic interaction of signaling pathways that drive mouse gastrulation.
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Affiliation(s)
- Sophie M Morgani
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, United States; Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Jeffrey Cheah Biomedical Centre Cambridge Biomedical Campus, Cambridge, United Kingdom.
| | - Anna-Katerina Hadjantonakis
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, United States.
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33
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Economou AD, Hill CS. Temporal dynamics in the formation and interpretation of Nodal and BMP morphogen gradients. Curr Top Dev Biol 2019; 137:363-389. [PMID: 32143749 DOI: 10.1016/bs.ctdb.2019.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
One of the most powerful ideas in developmental biology has been that of the morphogen gradient. In the classical view, a signaling molecule is produced at a local source from where it diffuses, resulting in graded levels across the tissue. This gradient provides positional information, with thresholds in the level of the morphogen determining the position of different cell fates. While experimental studies have uncovered numerous potential morphogens in biological systems, it is becoming increasingly apparent that one important feature, not captured in the simple model, is the role of time in both the formation and interpretation of morphogen gradients. We will focus on two members of the transforming growth factor-β family that are known to play a vital role as morphogens in early vertebrate development: the Nodals and the bone morphogenetic proteins (BMPs). Primarily drawing on the early zebrafish embryo, we will show how recent studies have demonstrated the importance of feedback and other interactions that evolve through time, in shaping morphogen gradients. We will further show how rather than simply reading out levels of a morphogen, the duration of ligand exposure can be a crucial determinant of how cells interpret morphogens, in particular through the unfolding of downstream transcriptional events and in their interactions with other pathways.
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Affiliation(s)
- Andrew D Economou
- Developmental Signalling Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Caroline S Hill
- Developmental Signalling Laboratory, The Francis Crick Institute, London, United Kingdom.
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34
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Chhabra S, Liu L, Goh R, Kong X, Warmflash A. Dissecting the dynamics of signaling events in the BMP, WNT, and NODAL cascade during self-organized fate patterning in human gastruloids. PLoS Biol 2019; 17:e3000498. [PMID: 31613879 PMCID: PMC6814242 DOI: 10.1371/journal.pbio.3000498] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 10/25/2019] [Accepted: 09/23/2019] [Indexed: 12/22/2022] Open
Abstract
During gastrulation, the pluripotent epiblast self-organizes into the 3 germ layers-endoderm, mesoderm and ectoderm, which eventually form the entire embryo. Decades of research in the mouse embryo have revealed that a signaling cascade involving the Bone Morphogenic Protein (BMP), WNT, and NODAL pathways is necessary for gastrulation. In vivo, WNT and NODAL ligands are expressed near the site of gastrulation in the posterior of the embryo, and knockout of these ligands leads to a failure to gastrulate. These data have led to the prevailing view that a signaling gradient in WNT and NODAL underlies patterning during gastrulation; however, the activities of these pathways in space and time have never been directly observed. In this study, we quantify BMP, WNT, and NODAL signaling dynamics in an in vitro model of human gastrulation. Our data suggest that BMP signaling initiates waves of WNT and NODAL signaling activity that move toward the colony center at a constant rate. Using a simple mathematical model, we show that this wave-like behavior is inconsistent with a reaction-diffusion-based Turing system, indicating that there is no stable signaling gradient of WNT/NODAL. Instead, the final signaling state is homogeneous, and spatial differences arise only from boundary effects. We further show that the durations of WNT and NODAL signaling control mesoderm differentiation, while the duration of BMP signaling controls differentiation of CDX2-positive extra-embryonic cells. The identity of these extra-embryonic cells has been controversial, and we use RNA sequencing (RNA-seq) to obtain their transcriptomes and show that they closely resemble human trophoblast cells in vivo. The domain of BMP signaling is identical to the domain of differentiation of these trophoblast-like cells; however, neither WNT nor NODAL forms a spatial pattern that maps directly to the mesodermal region, suggesting that mesoderm differentiation is controlled dynamically by the combinatorial effect of multiple signals. We synthesize our data into a mathematical model that accurately recapitulates signaling dynamics and predicts cell fate patterning upon chemical and physical perturbations. Taken together, our study shows that the dynamics of signaling events in the BMP, WNT, and NODAL cascade in the absence of a stable signaling gradient control fate patterning of human gastruloids.
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Affiliation(s)
- Sapna Chhabra
- Systems, Synthetic and Physical Biology, Rice University, Houston, Texas, United States of America
| | - Lizhong Liu
- Department of Biosciences, Rice University, Houston, Texas, United States of America
| | - Ryan Goh
- Department of Mathematics, Boston University, Boston, Massachusetts, United States of America
| | - Xiangyu Kong
- Department of Biosciences, Rice University, Houston, Texas, United States of America
| | - Aryeh Warmflash
- Department of Biosciences, Rice University, Houston, Texas, United States of America
- Department of Bioengineering, Rice University, Houston, Texas, United States of America
- * E-mail:
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35
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Abstract
Soon after fertilization the zebrafish embryo generates the pool of cells that will give rise to the germline and the three somatic germ layers of the embryo (ectoderm, mesoderm and endoderm). As the basic body plan of the vertebrate embryo emerges, evolutionarily conserved developmental signaling pathways, including Bmp, Nodal, Wnt, and Fgf, direct the nearly totipotent cells of the early embryo to adopt gene expression profiles and patterns of cell behavior specific to their eventual fates. Several decades of molecular genetics research in zebrafish has yielded significant insight into the maternal and zygotic contributions and mechanisms that pattern this vertebrate embryo. This new understanding is the product of advances in genetic manipulations and imaging technologies that have allowed the field to probe the cellular, molecular and biophysical aspects underlying early patterning. The current state of the field indicates that patterning is governed by the integration of key signaling pathways and physical interactions between cells, rather than a patterning system in which distinct pathways are deployed to specify a particular cell fate. This chapter focuses on recent advances in our understanding of the genetic and molecular control of the events that impart cell identity and initiate the patterning of tissues that are prerequisites for or concurrent with movements of gastrulation.
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Affiliation(s)
- Florence L Marlow
- Icahn School of Medicine Mount Sinai Department of Cell, Developmental and Regenerative Biology, New York, NY, United States.
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36
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Prummel KD, Hess C, Nieuwenhuize S, Parker HJ, Rogers KW, Kozmikova I, Racioppi C, Brombacher EC, Czarkwiani A, Knapp D, Burger S, Chiavacci E, Shah G, Burger A, Huisken J, Yun MH, Christiaen L, Kozmik Z, Müller P, Bronner M, Krumlauf R, Mosimann C. A conserved regulatory program initiates lateral plate mesoderm emergence across chordates. Nat Commun 2019; 10:3857. [PMID: 31451684 PMCID: PMC6710290 DOI: 10.1038/s41467-019-11561-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 07/22/2019] [Indexed: 01/06/2023] Open
Abstract
Cardiovascular lineages develop together with kidney, smooth muscle, and limb connective tissue progenitors from the lateral plate mesoderm (LPM). How the LPM initially emerges and how its downstream fates are molecularly interconnected remain unknown. Here, we isolate a pan-LPM enhancer in the zebrafish-specific draculin (drl) gene that provides specific LPM reporter activity from early gastrulation. In toto live imaging and lineage tracing of drl-based reporters captures the dynamic LPM emergence as lineage-restricted mesendoderm field. The drl pan-LPM enhancer responds to the transcription factors EomesoderminA, FoxH1, and MixL1 that combined with Smad activity drive LPM emergence. We uncover specific activity of zebrafish-derived drl reporters in LPM-corresponding territories of several chordates including chicken, axolotl, lamprey, Ciona, and amphioxus, revealing a universal upstream LPM program. Altogether, our work provides a mechanistic framework for LPM emergence as defined progenitor field, possibly representing an ancient mesodermal cell state that predates the primordial vertebrate embryo. Numerous tissues are derived from the lateral plate mesoderm (LPM) but how this is specified is unclear. Here, the authors identify a pan-LPM reporter activity found in the zebrafish draculin (drl) gene that also shows transgenic activity in LPM-corresponding territories of several chordates, including chicken, axolotl, lamprey, Ciona, and amphioxus.
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Affiliation(s)
- Karin D Prummel
- Institute of Molecular Life Sciences, University of Zurich, Zürich, 8057, Switzerland
| | - Christopher Hess
- Institute of Molecular Life Sciences, University of Zurich, Zürich, 8057, Switzerland
| | - Susan Nieuwenhuize
- Institute of Molecular Life Sciences, University of Zurich, Zürich, 8057, Switzerland
| | - Hugo J Parker
- Department of Anatomy and Cell Biology, Kansas University Medical Center, Kansas City, KS, 66160, USA.,Stowers Institute for Medical Research, Kansas City, MO, 64110, USA
| | - Katherine W Rogers
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, 72076, Germany
| | - Iryna Kozmikova
- Institute of Molecular Genetics of the ASCR, Prague, 142 20, Czech Republic
| | - Claudia Racioppi
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY, 10003, USA
| | - Eline C Brombacher
- Institute of Molecular Life Sciences, University of Zurich, Zürich, 8057, Switzerland
| | - Anna Czarkwiani
- TUD-CRTD Center for Regenerative Therapies Dresden, Dresden, 01307, Germany
| | - Dunja Knapp
- TUD-CRTD Center for Regenerative Therapies Dresden, Dresden, 01307, Germany
| | - Sibylle Burger
- Institute of Molecular Life Sciences, University of Zurich, Zürich, 8057, Switzerland
| | - Elena Chiavacci
- Institute of Molecular Life Sciences, University of Zurich, Zürich, 8057, Switzerland
| | - Gopi Shah
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, 01307, Germany
| | - Alexa Burger
- Institute of Molecular Life Sciences, University of Zurich, Zürich, 8057, Switzerland
| | - Jan Huisken
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, 01307, Germany.,Morgridge Institute for Research, Madison, WI, 53715, USA
| | - Maximina H Yun
- TUD-CRTD Center for Regenerative Therapies Dresden, Dresden, 01307, Germany.,Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, 01307, Germany
| | - Lionel Christiaen
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY, 10003, USA
| | - Zbynek Kozmik
- Institute of Molecular Genetics of the ASCR, Prague, 142 20, Czech Republic
| | - Patrick Müller
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, 72076, Germany
| | - Marianne Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Robb Krumlauf
- Department of Anatomy and Cell Biology, Kansas University Medical Center, Kansas City, KS, 66160, USA.,Stowers Institute for Medical Research, Kansas City, MO, 64110, USA
| | - Christian Mosimann
- Institute of Molecular Life Sciences, University of Zurich, Zürich, 8057, Switzerland.
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37
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Heemskerk I, Burt K, Miller M, Chhabra S, Guerra MC, Liu L, Warmflash A. Rapid changes in morphogen concentration control self-organized patterning in human embryonic stem cells. eLife 2019; 8:e40526. [PMID: 30829572 PMCID: PMC6398983 DOI: 10.7554/elife.40526] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 02/14/2019] [Indexed: 12/31/2022] Open
Abstract
During embryonic development, diffusible signaling molecules called morphogens are thought to determine cell fates in a concentration-dependent way. Yet, in mammalian embryos, concentrations change rapidly compared to the time for making cell fate decisions. Here, we use human embryonic stem cells (hESCs) to address how changing morphogen levels influence differentiation, focusing on how BMP4 and Nodal signaling govern the cell-fate decisions associated with gastrulation. We show that BMP4 response is concentration dependent, but that expression of many Nodal targets depends on rate of concentration change. Moreover, in a self-organized stem cell model for human gastrulation, expression of these genes follows rapid changes in endogenous Nodal signaling. Our study shows a striking contrast between the specific ways ligand dynamics are interpreted by two closely related signaling pathways, highlighting both the subtlety and importance of morphogen dynamics for understanding mammalian embryogenesis and designing optimized protocols for directed stem cell differentiation. Editorial note This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Idse Heemskerk
- Department of BiosciencesRice UniversityHoustonUnited States
| | - Kari Burt
- Department of BiosciencesRice UniversityHoustonUnited States
| | - Matthew Miller
- Department of BiosciencesRice UniversityHoustonUnited States
| | - Sapna Chhabra
- Systems, Synthetic and Physical Biology ProgramRice UniversityHoustonUnited States
| | | | - Lizhong Liu
- Department of BiosciencesRice UniversityHoustonUnited States
| | - Aryeh Warmflash
- Department of BiosciencesRice UniversityHoustonUnited States
- Department of BioengineeringRice UniversityHoustonUnited States
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38
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Zinski J, Tuazon F, Huang Y, Mullins M, Umulis D. Imaging and Quantification of P-Smad1/5 in Zebrafish Blastula and Gastrula Embryos. Methods Mol Biol 2019; 1891:135-154. [PMID: 30414130 DOI: 10.1007/978-1-4939-8904-1_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Spatiotemporal patterns of morphogen activity drive differential gene expression with a high degree of precision within a developing embryo and reproducibly between embryos. Understanding the formation and function of a morphogen gradient during development requires quantitative measurement of morphogen activity throughout an individual embryo and also between embryos within a population. Quantification of morphogen gradients in to presents unique challenges in imaging and image processing to minimize error and maximize the quality of the data so it may be used in computational models of development and in statistically testing hypotheses. Here we present methods for the preparation, immunostaining, imaging, and quantification of a bone morphogenetic protein (BMP) activity gradient in individual zebrafish embryos as well as methods for acquiring population-level statistics after embryo grouping and alignment. This quantitative approach can be extended to other morphogen systems, and the computational codes can be adapted to other imaging contexts in zebrafish and other organisms.
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Affiliation(s)
- Joseph Zinski
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Francesca Tuazon
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Yan Huang
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN, USA
| | - Mary Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
| | - David Umulis
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN, USA. .,Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA.
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39
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Sharma PP, MacLean AL, Meinecke L, Clouthier DE, Nie Q, Schilling TF. Transcriptomics reveals complex kinetics of dorsal-ventral patterning gene expression in the mandibular arch. Genesis 2018; 57:e23275. [PMID: 30561090 DOI: 10.1002/dvg.23275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/12/2018] [Accepted: 12/13/2018] [Indexed: 11/06/2022]
Abstract
The mandibular or first pharyngeal arch forms the upper and lower jaws in all gnathostomes. A gene regulatory network that defines ventral, intermediate, and dorsal domains along the dorsal-ventral (D-V) axis of the arch has emerged from studies in zebrafish and mice, but the temporal dynamics of this process remain unclear. To define cell fate trajectories in the arches we have performed quantitative gene expression analyses of D-V patterning genes in pharyngeal arch primordia in zebrafish and mice. Using NanoString technology to measure transcript numbers per cell directly we show that, in many cases, genes expressed in similar D-V domains and induced by similar signals vary dramatically in their temporal profiles. This suggests that cellular responses to D-V patterning signals are likely shaped by the baseline kinetics of target gene expression. Furthermore, similarities in the temporal dynamics of genes that occupy distinct pathways suggest novel shared modes of regulation. Incorporating these gene expression kinetics into our computational models for the mandibular arch improves the accuracy of patterning, and facilitates temporal comparisons between species. These data suggest that the magnitude and timing of target gene expression help diversify responses to patterning signals during craniofacial development.
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Affiliation(s)
- Praveer P Sharma
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California
| | - Adam L MacLean
- Department of Mathematics, University of California, Irvine, Irvine, California
| | - Lina Meinecke
- Department of Mathematics, University of California, Irvine, Irvine, California
| | - David E Clouthier
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Center, Aurora, Colorado
| | - Qing Nie
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California.,Department of Mathematics, University of California, Irvine, Irvine, California
| | - Thomas F Schilling
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California
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40
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Abstract
One challenge in biology is to make sense of the complexity of biological networks. A good system to approach this is signaling pathways, whose well-characterized molecular details allow us to relate the internal processes of each pathway to their input-output behavior. In this study, we analyzed mathematical models of three metazoan signaling pathways: the canonical Wnt, MAPK/ERK, and Tgfβ pathways. We find an unexpected convergence: the three pathways behave in some physiological contexts as linear signal transmitters. Testing the results experimentally, we present direct measurements of linear input-output behavior in the Wnt and ERK pathways. Analytics from each model further reveal that linearity arises through different means in each pathway, which we tested experimentally in the Wnt and ERK pathways. Linearity is a desired property in engineering where it facilitates fidelity and superposition in signal transmission. Our findings illustrate how cells tune different complex networks to converge on the same behavior.
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Affiliation(s)
- Harry Nunns
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
| | - Lea Goentoro
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
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41
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Liu Z, Woo S, Weiner OD. Nodal signaling has dual roles in fate specification and directed migration during germ layer segregation in zebrafish. Development 2018; 145:dev.163535. [PMID: 30111654 DOI: 10.1242/dev.163535] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 07/30/2018] [Indexed: 12/21/2022]
Abstract
During gastrulation, endodermal cells actively migrate to the interior of the embryo, but the signals that initiate and coordinate this migration are poorly understood. By transplanting ectopically induced endodermal cells far from the normal location of endoderm specification, we identified the inputs that drive internalization without the confounding influences of fate specification and global morphogenic movements. We find that Nodal signaling triggers an autocrine circuit for initiating endodermal internalization. Activation of the Nodal receptor directs endodermal specification through sox32 and also induces expression of more Nodal ligands. These ligands act in an autocrine fashion to initiate endodermal cell sorting. Our work defines an 'AND' gate consisting of sox32-dependent endodermal specification and Nodal ligand reception controlling endodermal cell sorting to the inner layer of the embryo at the onset of gastrulation.
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Affiliation(s)
- Zairan Liu
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Stephanie Woo
- Department of Molecular Cell Biology, School of Natural Sciences, University of California, Merced, CA 95343, USA
| | - Orion D Weiner
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA .,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
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42
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Abstract
TGF-β family ligands function in inducing and patterning many tissues of the early vertebrate embryonic body plan. Nodal signaling is essential for the specification of mesendodermal tissues and the concurrent cellular movements of gastrulation. Bone morphogenetic protein (BMP) signaling patterns tissues along the dorsal-ventral axis and simultaneously directs the cell movements of convergence and extension. After gastrulation, a second wave of Nodal signaling breaks the symmetry between the left and right sides of the embryo. During these processes, elaborate regulatory feedback between TGF-β ligands and their antagonists direct the proper specification and patterning of embryonic tissues. In this review, we summarize the current knowledge of the function and regulation of TGF-β family signaling in these processes. Although we cover principles that are involved in the development of all vertebrate embryos, we focus specifically on three popular model organisms: the mouse Mus musculus, the African clawed frog of the genus Xenopus, and the zebrafish Danio rerio, highlighting the similarities and differences between these species.
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Affiliation(s)
- Joseph Zinski
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6058
| | - Benjamin Tajer
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6058
| | - Mary C Mullins
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6058
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43
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Nelson AC, Cutty SJ, Gasiunas SN, Deplae I, Stemple DL, Wardle FC. In Vivo Regulation of the Zebrafish Endoderm Progenitor Niche by T-Box Transcription Factors. Cell Rep 2018; 19:2782-2795. [PMID: 28658625 PMCID: PMC5494305 DOI: 10.1016/j.celrep.2017.06.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 04/28/2017] [Accepted: 05/31/2017] [Indexed: 01/15/2023] Open
Abstract
T-box transcription factors T/Brachyury homolog A (Ta) and Tbx16 are essential for correct mesoderm development in zebrafish. The downstream transcriptional networks guiding their functional activities are poorly understood. Additionally, important contributions elsewhere are likely masked due to redundancy. Here, we exploit functional genomic strategies to identify Ta and Tbx16 targets in early embryogenesis. Surprisingly, we discovered they not only activate mesodermal gene expression but also redundantly regulate key endodermal determinants, leading to substantial loss of endoderm in double mutants. To further explore the gene regulatory networks (GRNs) governing endoderm formation, we identified targets of Ta/Tbx16-regulated homeodomain transcription factor Mixl1, which is absolutely required in zebrafish for endoderm formation. Interestingly, we find many endodermal determinants coordinately regulated through common genomic occupancy by Mixl1, Eomesa, Smad2, Nanog, Mxtx2, and Pou5f3. Collectively, these findings augment the endoderm GRN and reveal a panel of target genes underlying the Ta, Tbx16, and Mixl1 mutant phenotypes.
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Affiliation(s)
- Andrew C Nelson
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK; Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK; School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
| | - Stephen J Cutty
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Saule N Gasiunas
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Isabella Deplae
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Derek L Stemple
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Fiona C Wardle
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK.
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44
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Nodal and BMP dispersal during early zebrafish development. Dev Biol 2018; 447:14-23. [PMID: 29653088 DOI: 10.1016/j.ydbio.2018.04.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 03/29/2018] [Accepted: 04/06/2018] [Indexed: 12/30/2022]
Abstract
The secreted TGF-β superfamily signals Nodal and BMP coordinate the patterning of vertebrate embryos. Nodal specifies endoderm and mesoderm during germ layer formation, and BMP specifies ventral fates and patterns the dorsal/ventral axis. Five major models have been proposed to explain how the correct distributions of Nodal and BMP are achieved within tissues to orchestrate embryogenesis: source/sink, transcriptional determination, relay, self-regulation, and shuttling. Here, we discuss recent experiments probing these signal dispersal models, focusing on early zebrafish development.
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45
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Hill CS. Spatial and temporal control of NODAL signaling. Curr Opin Cell Biol 2018; 51:50-57. [PMID: 29153705 DOI: 10.1016/j.ceb.2017.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 12/21/2022]
Abstract
Embryonic development is orchestrated by the activity of signal transduction pathways, amongst which are those downstream of the transforming growth factor β (TGF-β) family. Here I focus on signalling by one of these ligands, NODAL, which is essential for early embryonic axis patterning. I review recent advances in our understanding of how NODAL signalling is transduced from the plasma membrane to the nucleus to regulate the transcription of target genes, and how domains of NODAL activity are established and refined during embryonic development. The duration of signalling is emerging as a key determinant of the specificity of downstream responses in terms of cell fate decisions and I will discuss what is currently known about the underlying mechanisms.
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Affiliation(s)
- Caroline S Hill
- Developmental Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
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46
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Vopalensky P, Pralow S, Vastenhouw NL. Reduced expression of the Nodal co-receptor Oep causes loss of mesendodermal competence in zebrafish. Development 2018; 145:dev.158832. [PMID: 29440298 DOI: 10.1242/dev.158832] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 01/29/2018] [Indexed: 12/17/2022]
Abstract
The activation of specific gene expression programs depends on the presence of the appropriate signals and the competence of cells to respond to those signals. Although it is well established that cellular competence is regulated in space and time, the molecular mechanisms underlying the loss of competence remain largely unknown. Here, we determine the time window during which zebrafish prospective ectoderm loses its ability to respond to Nodal signals, and show that this coincides with a decrease in the levels of the Nodal co-receptor One-eyed pinhead (Oep). Bypassing Oep using a photoactivatable receptor, or an Oep-independent ligand, allows activation of Nodal target genes for an extended period of time. These results suggest that the reduced expression of Oep causes the loss of responsiveness to Nodal signals in the prospective ectoderm. Indeed, extending the presence of Oep prolongs the window of competence to respond to Nodal signals. Our findings suggest a simple mechanism in which the decreasing level of one component of the Nodal signaling pathway regulates the loss of mesendodermal competence in the prospective ectoderm.
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Affiliation(s)
- Pavel Vopalensky
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Sabrina Pralow
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Nadine L Vastenhouw
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany
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47
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van Boxtel AL, Economou AD, Heliot C, Hill CS. Long-Range Signaling Activation and Local Inhibition Separate the Mesoderm and Endoderm Lineages. Dev Cell 2018; 44:179-191.e5. [PMID: 29275993 PMCID: PMC5791662 DOI: 10.1016/j.devcel.2017.11.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 10/20/2017] [Accepted: 11/27/2017] [Indexed: 12/20/2022]
Abstract
Specification of the three germ layers by graded Nodal signaling has long been seen as a paradigm for patterning through a single morphogen gradient. However, by exploiting the unique properties of the zebrafish embryo to capture the dynamics of signaling and cell fate allocation, we now demonstrate that Nodal functions in an incoherent feedforward loop, together with Fgf, to determine the pattern of endoderm and mesoderm specification. We show that Nodal induces long-range Fgf signaling while simultaneously inducing the cell-autonomous Fgf signaling inhibitor Dusp4 within the first two cell tiers from the margin. The consequent attenuation of Fgf signaling in these cells allows specification of endoderm progenitors, while the cells further from the margin, which receive Nodal and/or Fgf signaling, are specified as mesoderm. This elegant model demonstrates the necessity of feedforward and feedback interactions between multiple signaling pathways for providing cells with temporal and positional information.
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Affiliation(s)
- Antonius L van Boxtel
- Developmental Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Andrew D Economou
- Developmental Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Claire Heliot
- Developmental Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Caroline S Hill
- Developmental Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
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48
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Abstract
Experiments by three independent groups on zebrafish have clarified the role of two signaling factors, Nodal and Gdf3, during the early stages of development
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Affiliation(s)
- Benjamin Tajer
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, United States
| | - Mary C Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, United States
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49
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Wang Z, Nakayama Y, Tsuda S, Yamasu K. The role of gastrulation brain homeobox 2 (gbx2) in the development of the ventral telencephalon in zebrafish embryos. Differentiation 2017; 99:28-40. [PMID: 29289755 DOI: 10.1016/j.diff.2017.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 12/18/2017] [Accepted: 12/20/2017] [Indexed: 02/03/2023]
Abstract
During vertebrate brain development, the gastrulation brain homeobox 2 gene (gbx2) is expressed in the forebrain, but its precise roles are still unknown. In this study, we addressed this issue in zebrafish (Danio rerio) first by carefully examining gbx2 expression in the developing forebrain. We showed that gbx2 was expressed in the telencephalon during late somitogenesis, from 18h post-fertilization (hpf) to 24 hpf, and in the thalamic primordium after 26 hpf. In contrast, another gbx gene, gbx1, was expressed in the anterior-most ventral telencephalon after 36 hpf. Thus, the expression patterns of these two gbx genes did not overlap, arguing against their redundant function in the forebrain. Two-color fluorescence in situ hybridization (FISH) showed close relationships between the telencephalic expression of gbx2 and other forebrain-forming genes, suggesting that their interactions contribute to the regionalization of the telencephalon. FISH further revealed that gbx2 is expressed in the ventricular region of the telencephalon. By using transgenic fish in which gbx2 can be induced by heat shock, we found that gbx2 induction at 16 hpf repressed the expression of emx3, dlx2a, and six3b in the ventral telencephalon. Among secreted factor genes, bmp2b and wnt1 were repressed in the vicinity of the gbx2 domain in the telencephalon. The expression of forebrain-forming genes was examined in mutant embryos lacking gbx2, showing emx3 and dlx2a to be upregulated in the subpallium at 24 hpf. Taken together, these findings indicate that gbx2 contributes to the development of the subpallium through its repressive activities against other telencephalon-forming genes. We further showed that inhibiting FGF signaling and activating Wnt signaling repressed gbx2 and affected the regionalization of the telencephalon, supporting a functional link between gbx2, intracellular signaling, and telencephalon development.
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Affiliation(s)
- Zhe Wang
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Yukiko Nakayama
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Sachiko Tsuda
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan; Saitama University Brain Science Institute, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan; Research and Development Bureau, Saitama University, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Kyo Yamasu
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan; Saitama University Brain Science Institute, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
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50
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Rogers KW, Lord ND, Gagnon JA, Pauli A, Zimmerman S, Aksel DC, Reyon D, Tsai SQ, Joung JK, Schier AF. Nodal patterning without Lefty inhibitory feedback is functional but fragile. eLife 2017; 6. [PMID: 29215332 PMCID: PMC5720593 DOI: 10.7554/elife.28785] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 11/07/2017] [Indexed: 12/12/2022] Open
Abstract
Developmental signaling pathways often activate their own inhibitors. Such inhibitory feedback has been suggested to restrict the spatial and temporal extent of signaling or mitigate signaling fluctuations, but these models are difficult to rigorously test. Here, we determine whether the ability of the mesendoderm inducer Nodal to activate its inhibitor Lefty is required for development. We find that zebrafish lefty mutants exhibit excess Nodal signaling and increased specification of mesendoderm, resulting in embryonic lethality. Strikingly, development can be fully restored without feedback: Lethal patterning defects in lefty mutants can be rescued by ectopic expression of lefty far from its normal expression domain or by spatially and temporally uniform exposure to a Nodal inhibitor drug. While drug-treated mutants are less tolerant of mild perturbations to Nodal signaling levels than wild type embryos, they can develop into healthy adults. These results indicate that patterning without inhibitory feedback is functional but fragile. During animal development, a single fertilized cell gives rise to different tissues and organs. This ‘patterning’ process depends on signaling molecules that instruct cells in different positions in the embryo to acquire different identities. To avoid mistakes during patterning, each cell must receive the correct amount of signal at the appropriate time. In a process called ‘inhibitory feedback’, a signaling molecule instructs cells to produce molecules that block its own signaling. Although inhibitory feedback is widely used during patterning in organisms ranging from sea urchins to mammals, its exact purpose is often not clear. In part this is because feedback is challenging to experimentally manipulate. Removing the inhibitor disrupts feedback, but also increases signaling. Since the effects of broken feedback and increased signaling are intertwined, any resulting developmental defects do not provide information about what feedback specifically does. In order to examine the role of feedback, it is therefore necessary to disconnect the production of the inhibitor from the signaling process. In developing embryos, a well-known signaling molecule called Nodal instructs cells to become specific types – for example, a heart or gut cell. Nodal also promotes the production of its inhibitor, Lefty. To understand how this feedback system works, Rogers, Lord et al. first removed Lefty from zebrafish embryos. These embryos had excessive levels of Nodal signaling, did not develop correctly, and could not survive. Bathing the embryos in a drug that inhibits Nodal reduced excess signaling and allowed them to develop successfully. In these drug-treated embryos, inhibitor production is disconnected from the signaling process, allowing the role of feedback to be examined. Drug-treated embryos were less able to tolerate fluctuations in Nodal signaling than normal zebrafish embryos, which could compensate for such disturbances by adjusting Lefty levels. Overall, it appears that inhibitory feedback in this patterning system is important to compensate for alterations in Nodal signaling, but is not essential for development. Understanding the role of inhibitory feedback will be useful for efforts to grow tissues and organs in the laboratory for clinical use. The results presented by Rogers, Lord et al. also suggest the possibility that drug treatments could be developed to help correct birth defects in the womb.
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Affiliation(s)
- Katherine W Rogers
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Nathan D Lord
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - James A Gagnon
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Andrea Pauli
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Steven Zimmerman
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Deniz C Aksel
- Program in Biophysics, Harvard Medical School, Boston, United States
| | - Deepak Reyon
- Molecular Pathology Unit, Massachusetts General Hospital, Charlestown, United States.,Department of Pathology, Harvard Medical School, Boston, United States.,Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, United States.,Center for Cancer Research, Massachusetts General Hospital, Charlestown, United States
| | - Shengdar Q Tsai
- Molecular Pathology Unit, Massachusetts General Hospital, Charlestown, United States.,Department of Pathology, Harvard Medical School, Boston, United States.,Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, United States.,Center for Cancer Research, Massachusetts General Hospital, Charlestown, United States
| | - J Keith Joung
- Molecular Pathology Unit, Massachusetts General Hospital, Charlestown, United States.,Department of Pathology, Harvard Medical School, Boston, United States.,Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, United States.,Center for Cancer Research, Massachusetts General Hospital, Charlestown, United States
| | - Alexander F Schier
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,Broad Institute of MIT and Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States.,Harvard Stem Cell Institute, Harvard University, Cambridge, United States.,Center for Systems Biology, Harvard University, Cambridge, United States
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