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Mullan TW, Felton T, Tam J, Kasem O, Yeung TJ, Memar N, Schnabel R, Poole RJ. Control of successive unequal cell divisions by neural cell fate regulators determines embryonic neuroblast cell size. Development 2024; 151:dev200981. [PMID: 38205939 PMCID: PMC10911278 DOI: 10.1242/dev.200981] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 01/02/2024] [Indexed: 01/12/2024]
Abstract
Asymmetric cell divisions often generate daughter cells of unequal size in addition to different fates. In some contexts, daughter cell size asymmetry is thought to be a key input to specific binary cell fate decisions. An alternative possibility is that unequal division is a mechanism by which a variety of cells of different sizes are generated during embryonic development. We show here that two unequal cell divisions precede neuroblast formation in the C lineage of Caenorhabditis elegans. The equalisation of these divisions in a pig-1/MELK mutant background has little effect on neuroblast specification. Instead, we demonstrate that let-19/MDT13 is a regulator of the proneural basic helix-loop-helix transcription factor hlh-14/ASCL1 and find that both are required to concomitantly regulate the acquisition of neuroblast identity and neuroblast cell size. Thus, embryonic neuroblast cell size in this lineage is progressively regulated in parallel with identity by key neural cell fate regulators. We propose that key cell fate determinants have a previously unappreciated function in regulating unequal cleavage, and therefore cell size, of the progenitor cells whose daughter cell fates they then go on to specify.
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Affiliation(s)
- Thomas W. Mullan
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Terry Felton
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Janis Tam
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Osama Kasem
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Tim J. Yeung
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Nadin Memar
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
- Institut für Genetik, TU Braunschweig, D-38106 Braunschweig, Germany
| | - Ralf Schnabel
- Institut für Genetik, TU Braunschweig, D-38106 Braunschweig, Germany
| | - Richard J. Poole
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
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2
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Funakoshi HM, Shito TT, Oka K, Hotta K. Developmental Table and Three-Dimensional Embryological Image Resource of the Ascidian Ascidiella aspersa. Front Cell Dev Biol 2021; 9:789046. [PMID: 34977032 PMCID: PMC8718802 DOI: 10.3389/fcell.2021.789046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 11/29/2021] [Indexed: 11/13/2022] Open
Abstract
Ascidiella aspersa is an ascidian in the class of chordates—the closest relatives of vertebrates. A. aspersa is a potential model organism for bio-imaging studies due to its extremely transparent embryos as well as is a globally distributed cosmopolitan species. However, there is no standard developmental table for this organism. Here, as a first step to establish A. aspersa as a model organism, we report a standard developmental table as a web-based digital image resource. This resource used confocal laser scanning microscopy to scan more than 3,000 cross-sectional images and 3D-reconstructed images of A. aspersa embryos during embryogenesis. With reference to the standardized developmental table of Ciona intestinalis type A, 26 different developmental stages (Stages 1–26) from fertilized eggs to hatched larvae were redefined for A. aspersa. Cell lineages up to the cleavage period were annotated: The cleavage patterns, the embryonic morphology, and the developmental time were then compared with Ciona. We found that the cleavage patterns and developmental time up to the neurula period in A. aspersa were extremely conserved versus. Ciona. The ratio of the trunk and tail length in the tailbud period were smaller than Ciona indicating a relatively short tail. In addition, the timing of the bending of the tail is earlier than Ciona. This A. aspersa standard 3D digital resource is essential for connecting different omics data to different spatiotemporal hierarchies and is useful for a system-level understanding of chordate development and evolution.
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Affiliation(s)
- Haruka M. Funakoshi
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan
| | - Takumi T. Shito
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan
| | - Kotaro Oka
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan
- Waseda Research Institute for Science and Engineering, Waseda University, Shinjuku, Japan
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City, Taiwan
| | - Kohji Hotta
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan
- *Correspondence: Kohji Hotta,
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Godard BG, Dumollard R, Heisenberg CP, McDougall A. Combined effect of cell geometry and polarity domains determines the orientation of unequal division. eLife 2021; 10:75639. [PMID: 34889186 PMCID: PMC8691831 DOI: 10.7554/elife.75639] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 12/02/2021] [Indexed: 11/13/2022] Open
Abstract
Cell division orientation is thought to result from a competition between cell geometry and polarity domains controlling the position of the mitotic spindle during mitosis. Depending on the level of cell shape anisotropy or the strength of the polarity domain, one dominates the other and determines the orientation of the spindle. Whether and how such competition is also at work to determine unequal cell division (UCD), producing daughter cells of different size, remains unclear. Here, we show that cell geometry and polarity domains cooperate, rather than compete, in positioning the cleavage plane during UCDs in early ascidian embryos. We found that the UCDs and their orientation at the ascidian third cleavage rely on the spindle tilting in an anisotropic cell shape, and cortical polarity domains exerting different effects on spindle astral microtubules. By systematically varying mitotic cell shape, we could modulate the effect of attractive and repulsive polarity domains and consequently generate predicted daughter cell size asymmetries and position. We therefore propose that the spindle position during UCD is set by the combined activities of cell geometry and polarity domains, where cell geometry modulates the effect of cortical polarity domain(s).
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Affiliation(s)
- Benoit G Godard
- Laboratoire de Biologie du Développement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, Villefranche sur Mer, France.,Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Remi Dumollard
- Laboratoire de Biologie du Développement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, Villefranche sur Mer, France
| | | | - Alex McDougall
- Laboratoire de Biologie du Développement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, Villefranche sur Mer, France
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Winkley KM, Reeves WM, Veeman MT. Single-cell analysis of cell fate bifurcation in the chordate Ciona. BMC Biol 2021; 19:180. [PMID: 34465302 PMCID: PMC8408944 DOI: 10.1186/s12915-021-01122-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/12/2021] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Inductive signaling interactions between different cell types are a major mechanism for the further diversification of embryonic cell fates. Most blastomeres in the model chordate Ciona robusta become restricted to a single predominant fate between the 64-cell and mid-gastrula stages. The deeply stereotyped and well-characterized Ciona embryonic cell lineages allow the transcriptomic analysis of newly established cell types very early in their divergence from sibling cell states without the pseudotime inference needed in the analysis of less synchronized cell populations. This is the first ascidian study to use droplet scRNAseq with large numbers of analyzed cells as early as the 64-cell stage when major lineages such as primary notochord first become fate restricted. RESULTS AND CONCLUSIONS We identify 59 distinct cell states, including new subregions of the b-line neural lineage and the early induction of the tail tip epidermis. We find that 34 of these cell states are directly or indirectly dependent on MAPK-mediated signaling critical to early Ciona patterning. Most of the MAPK-dependent bifurcations are canalized with the signal-induced cell fate lost upon MAPK inhibition, but the posterior endoderm is unique in being transformed into a novel state expressing some but not all markers of both endoderm and muscle. Divergent gene expression between newly bifurcated sibling cell types is dominated by upregulation in the induced cell type. The Ets family transcription factor Elk1/3/4 is uniquely upregulated in nearly all the putatively direct inductions. Elk1/3/4 upregulation together with Ets transcription factor binding site enrichment analysis enables inferences about which bifurcations are directly versus indirectly controlled by MAPK signaling. We examine notochord induction in detail and find that the transition between a Zic/Ets-mediated regulatory state and a Brachyury/FoxA-mediated regulatory state is unexpectedly late. This supports a "broad-hourglass" model of cell fate specification in which many early tissue-specific genes are induced in parallel to key tissue-specific transcriptional regulators via the same set of transcriptional inputs.
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Affiliation(s)
- Konner M Winkley
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Wendy M Reeves
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Michael T Veeman
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA.
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5
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Fiuza UM, Lemaire P. Mechanical and genetic control of ascidian endoderm invagination during gastrulation. Semin Cell Dev Biol 2021; 120:108-118. [PMID: 34393069 DOI: 10.1016/j.semcdb.2021.08.001] [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: 05/08/2021] [Revised: 07/26/2021] [Accepted: 08/02/2021] [Indexed: 10/20/2022]
Abstract
Gastrulation is a near universal developmental process of animal embryogenesis, during which dramatic morphogenetic events take place: the mesodermal and endodermal tissues are internalized, the ectoderm spreads to cover the embryo surface, and the animal body plan and germ layers are established. Morphogenesis during gastrulation has long been considered the result of spatio-temporally localised forces driven by the transcriptional programme of the embryo. Recent work has shown that tissue rheological properties, which define the mechanical response of tissues to internally-generated or external forces, are also important dynamic regulators of gastrulation. Here, we first introduce how embryonic mechanics can be represented, before outlining current knowledge of the mechanical and genetic control of gastrulation in ascidians, invertebrate marine chordates which develop with invariant cell lineages and a solid-like rheological behaviour until the neurula stages. We discuss the potential of these organisms for the experimental and computational whole-embryo characterisation of the mechanisms shaping gastrulation, and how they may inform the more complex tissue internalization strategies used by other model organisms.
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Affiliation(s)
- Ulla-Maj Fiuza
- Systems Bioengineering, DCEXS, Universidad Pompeu Fabra, Doctor Aiguader, 88, 08003 Barcelona, Spain.
| | - Patrick Lemaire
- Centre de Recherches de Biologie cellulaire de Montpellier, CRBM, Université de Montpellier, CNRS, 1919 route de Mende, Montpellier, France.
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Hitomi M, Chumakova AP, Silver DJ, Knudsen AM, Pontius WD, Murphy S, Anand N, Kristensen BW, Lathia JD. Asymmetric cell division promotes therapeutic resistance in glioblastoma stem cells. JCI Insight 2021; 6:130510. [PMID: 33351787 PMCID: PMC7934841 DOI: 10.1172/jci.insight.130510] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 12/16/2020] [Indexed: 02/06/2023] Open
Abstract
Asymmetric cell division (ACD) enables the maintenance of a stem cell population while simultaneously generating differentiated progeny. Cancer stem cells (CSCs) undergo multiple modes of cell division during tumor expansion and in response to therapy, yet the functional consequences of these division modes remain to be determined. Using a fluorescent reporter for cell surface receptor distribution during mitosis, we found that ACD generated a daughter cell with enhanced therapeutic resistance and increased coenrichment of EGFR and neurotrophin receptor (p75NTR) from a glioblastoma CSC. Stimulation of both receptors antagonized differentiation induction and promoted self-renewal capacity. p75NTR knockdown enhanced the therapeutic efficacy of EGFR inhibition, indicating that coinheritance of p75NTR and EGFR promotes resistance to EGFR inhibition through a redundant mechanism. These data demonstrate that ACD produces progeny with coenriched growth factor receptors, which contributes to the generation of a more therapeutically resistant CSC population.
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Affiliation(s)
- Masahiro Hitomi
- Cancer Impact Area, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, USA
| | - Anastasia P Chumakova
- Cancer Impact Area, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Daniel J Silver
- Cancer Impact Area, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, USA.,Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, USA
| | - Arnon M Knudsen
- Department of Pathology, Odense University Hospital, Odense, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - W Dean Pontius
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, USA
| | - Stephanie Murphy
- Cancer Impact Area, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Neha Anand
- Cancer Impact Area, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Bjarne W Kristensen
- Department of Pathology, Odense University Hospital, Odense, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Justin D Lathia
- Cancer Impact Area, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, USA.,Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, USA.,Rose Ella Burkhardt Brain Tumor and Neuro-Oncology Center, Cleveland, Ohio, USA
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7
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Harder MJ, Hix J, Reeves WM, Veeman MT. Ciona Brachyury proximal and distal enhancers have different FGF dose-response relationships. PLoS Genet 2021; 17:e1009305. [PMID: 33465083 PMCID: PMC7846015 DOI: 10.1371/journal.pgen.1009305] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 01/29/2021] [Accepted: 12/10/2020] [Indexed: 12/12/2022] Open
Abstract
Many genes are regulated by two or more enhancers that drive similar expression patterns. Evolutionary theory suggests that these seemingly redundant enhancers must have functionally important differences. In the simple ascidian chordate Ciona, the transcription factor Brachyury is induced exclusively in the presumptive notochord downstream of lineage specific regulators and FGF-responsive Ets family transcription factors. Here we exploit the ability to finely titrate FGF signaling activity via the MAPK pathway using the MEK inhibitor U0126 to quantify the dependence of transcription driven by different Brachyury reporter constructs on this direct upstream regulator. We find that the more powerful promoter-adjacent proximal enhancer and a weaker distal enhancer have fundamentally different dose-response relationships to MAPK inhibition. The Distal enhancer is more sensitive to MAPK inhibition but shows a less cooperative response, whereas the Proximal enhancer is less sensitive and more cooperative. A longer construct containing both enhancers has a complex dose-response curve that supports the idea that the proximal and distal enhancers are moderately super-additive. We show that the overall expression loss from intermediate doses of U0126 is not only a function of the fraction of cells expressing these reporters, but also involves graded decreases in expression at the single-cell level. Expression of the endogenous gene shows a comparable dose-response relationship to the full length reporter, and we find that different notochord founder cells are differentially sensitive to MAPK inhibition. Together, these results indicate that although the two Brachyury enhancers have qualitatively similar expression patterns, they respond to FGF in quantitatively different ways and act together to drive high levels of Brachyury expression with a characteristic input/output relationship. This indicates that they are fundamentally not equivalent genetic elements. When and where genes are expressed is controlled by regulatory DNA regions known as enhancers. Genes often have multiple enhancers that control expression in different cell types or embryonic regions, but there are also genes that have multiple enhancers that control near-identical expression patterns. These ‘shadow’ enhancers are common features of many animal genomes, but it is unclear to what extent they are truly identical in function. Here we studied a pair of shadow enhancers for the notochord-specific gene Brachyury in the simple model chordate Ciona that are both directly activated by the same signaling pathway. We titrated the activity of this pathway with graded doses of a pharmacological inhibitor and measured the effects in quantitative enhancer assays. We found that the two enhancers had significant differences in sensitivity and cooperativity to the same shared regulator and are thus not identical in function when assessed quantitatively. We also identified subtle differences in sensitivity to this upstream signal between different notochord precursor cells.
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Affiliation(s)
- Matthew J. Harder
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Julie Hix
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Wendy M. Reeves
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Michael T. Veeman
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
- * E-mail:
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Abstract
Asymmetric cell division (ACD) is an evolutionarily conserved mechanism used by prokaryotes and eukaryotes alike to control cell fate and generate cell diversity. A detailed mechanistic understanding of ACD is therefore necessary to understand cell fate decisions in health and disease. ACD can be manifested in the biased segregation of macromolecules, the differential partitioning of cell organelles, or differences in sibling cell size or shape. These events are usually preceded by and influenced by symmetry breaking events and cell polarization. In this Review, we focus predominantly on cell intrinsic mechanisms and their contribution to cell polarization, ACD and binary cell fate decisions. We discuss examples of polarized systems and detail how polarization is established and, whenever possible, how it contributes to ACD. Established and emerging model organisms will be considered alike, illuminating both well-documented and underexplored forms of polarization and ACD.
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Affiliation(s)
- Bharath Sunchu
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA
| | - Clemens Cabernard
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA
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Di Gregorio A. The notochord gene regulatory network in chordate evolution: Conservation and divergence from Ciona to vertebrates. Curr Top Dev Biol 2020; 139:325-374. [PMID: 32450965 DOI: 10.1016/bs.ctdb.2020.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The notochord is a structure required for support and patterning of all chordate embryos, from sea squirts to humans. An increasing amount of information on notochord development and on the molecular strategies that ensure its proper morphogenesis has been gleaned through studies in the sea squirt Ciona. This invertebrate chordate offers a fortunate combination of experimental advantages, ranging from translucent, fast-developing embryos to a compact genome and impressive biomolecular resources. These assets have enabled the rapid identification of numerous notochord genes and cis-regulatory regions, and provide a rather unique opportunity to reconstruct the gene regulatory network that controls the formation of this developmental and evolutionary chordate landmark. This chapter summarizes the morphogenetic milestones that punctuate notochord formation in Ciona, their molecular effectors, and the current knowledge of the gene regulatory network that ensures the accurate spatial and temporal orchestration of these processes.
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Affiliation(s)
- Anna Di Gregorio
- Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY, United States.
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