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Zhu K, Spaink HP, Durston AJ. Patterning of the Vertebrate Head in Time and Space by BMP Signaling. J Dev Biol 2023; 11:31. [PMID: 37489332 PMCID: PMC10366882 DOI: 10.3390/jdb11030031] [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: 01/10/2023] [Revised: 06/19/2023] [Accepted: 06/27/2023] [Indexed: 07/26/2023] Open
Abstract
How head patterning is regulated in vertebrates is yet to be understood. In this study, we show that frog embryos injected with Noggin at different blastula and gastrula stages had their head development sequentially arrested at different positions. When timed BMP inhibition was applied to BMP-overexpressing embryos, the expression of five genes: xcg-1 (a marker of the cement gland, which is the front-most structure in the frog embryo), six3 (a forebrain marker), otx2 (a forebrain and mid-brain marker), gbx2 (an anterior hindbrain marker), and hoxd1 (a posterior hindbrain marker) were sequentially fixed. These results suggest that the vertebrate head is patterned from anterior to posterior in a progressive fashion and may involve timed actions of the BMP signaling.
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Affiliation(s)
- Kongju Zhu
- Institute of Biology, Leiden University, Sylviusweg 72, 2333BE Leiden, The Netherlands
- Department of Pathology, Brigham and Women's Hospital, 60 Fenwood Road, Boston, MA 02115, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Division of Genetics and Genomics, Boston Children's Hospital, Center for Life Sciences, Blackfan Circle, Boston, MA 02115, USA
| | - Herman P Spaink
- Institute of Biology, Leiden University, Sylviusweg 72, 2333BE Leiden, The Netherlands
| | - Antony J Durston
- Institute of Biology, Leiden University, Sylviusweg 72, 2333BE Leiden, The Netherlands
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2
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Sampath Kumar A, Tian L, Bolondi A, Hernández AA, Stickels R, Kretzmer H, Murray E, Wittler L, Walther M, Barakat G, Haut L, Elkabetz Y, Macosko EZ, Guignard L, Chen F, Meissner A. Spatiotemporal transcriptomic maps of whole mouse embryos at the onset of organogenesis. Nat Genet 2023; 55:1176-1185. [PMID: 37414952 PMCID: PMC10335937 DOI: 10.1038/s41588-023-01435-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 05/25/2023] [Indexed: 07/08/2023]
Abstract
Spatiotemporal orchestration of gene expression is required for proper embryonic development. The use of single-cell technologies has begun to provide improved resolution of early regulatory dynamics, including detailed molecular definitions of most cell states during mouse embryogenesis. Here we used Slide-seq to build spatial transcriptomic maps of complete embryonic day (E) 8.5 and E9.0, and partial E9.5 embryos. To support their utility, we developed sc3D, a tool for reconstructing and exploring three-dimensional 'virtual embryos', which enables the quantitative investigation of regionalized gene expression patterns. Our measurements along the main embryonic axes of the developing neural tube revealed several previously unannotated genes with distinct spatial patterns. We also characterized the conflicting transcriptional identity of 'ectopic' neural tubes that emerge in Tbx6 mutant embryos. Taken together, we present an experimental and computational framework for the spatiotemporal investigation of whole embryonic structures and mutant phenotypes.
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Affiliation(s)
- Abhishek Sampath Kumar
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
- Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Luyi Tian
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Adriano Bolondi
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Amèlia Aragonés Hernández
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Robert Stickels
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Graduate School of Arts and Sciences, Harvard University, Cambridge, MA, USA
| | - Helene Kretzmer
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Evan Murray
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Lars Wittler
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Maria Walther
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Gabriel Barakat
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Leah Haut
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Yechiel Elkabetz
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Evan Z Macosko
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
| | - Léo Guignard
- Aix Marseille University, Toulon University, Centre National de la Recherche Scientifique, Laboratoire d'Informatique et Systèmes 7020, Turing Centre for Living Systems, Marseille, France
| | - Fei Chen
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA
| | - Alexander Meissner
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA.
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3
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Tomas-Roca L, Qiu Z, Fransén E, Gokhale R, Bulovaite E, Price DJ, Komiyama NH, Grant SGN. Developmental disruption and restoration of brain synaptome architecture in the murine Pax6 neurodevelopmental disease model. Nat Commun 2022; 13:6836. [PMID: 36369219 PMCID: PMC9652404 DOI: 10.1038/s41467-022-34131-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 10/14/2022] [Indexed: 11/13/2022] Open
Abstract
Neurodevelopmental disorders of genetic origin delay the acquisition of normal abilities and cause disabling phenotypes. Nevertheless, spontaneous attenuation and even complete amelioration of symptoms in early childhood and adolescence can occur in many disorders, suggesting that brain circuits possess an intrinsic capacity to overcome the deficits arising from some germline mutations. We examined the molecular composition of almost a trillion excitatory synapses on a brain-wide scale between birth and adulthood in mice carrying a mutation in the homeobox transcription factor Pax6, a neurodevelopmental disorder model. Pax6 haploinsufficiency had no impact on total synapse number at any age. By contrast, the molecular composition of excitatory synapses, the postnatal expansion of synapse diversity and the acquisition of normal synaptome architecture were delayed in all brain regions, interfering with networks and electrophysiological simulations of cognitive functions. Specific excitatory synapse types and subtypes were affected in two key developmental age-windows. These phenotypes were reversed within 2-3 weeks of onset, restoring synapse diversity and synaptome architecture to the normal developmental trajectory. Synapse subtypes with rapid protein turnover mediated the synaptome remodeling. This brain-wide capacity for remodeling of synapse molecular composition to recover and maintain the developmental trajectory of synaptome architecture may help confer resilience to neurodevelopmental genetic disorders.
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Affiliation(s)
- Laura Tomas-Roca
- grid.4305.20000 0004 1936 7988Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB UK
| | - Zhen Qiu
- grid.4305.20000 0004 1936 7988Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB UK
| | - Erik Fransén
- grid.5037.10000000121581746Science for Life Laboratory, KTH Royal Institute of Technology, SE-171 65 Solna, Sweden
| | - Ragini Gokhale
- grid.4305.20000 0004 1936 7988Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB UK
| | - Edita Bulovaite
- grid.4305.20000 0004 1936 7988Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB UK
| | - David J. Price
- grid.4305.20000 0004 1936 7988Simons Initiative for the Developing Brain (SIDB), Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD UK
| | - Noboru H. Komiyama
- grid.4305.20000 0004 1936 7988Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB UK ,grid.4305.20000 0004 1936 7988Simons Initiative for the Developing Brain (SIDB), Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD UK
| | - Seth G. N. Grant
- grid.4305.20000 0004 1936 7988Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB UK ,grid.4305.20000 0004 1936 7988Simons Initiative for the Developing Brain (SIDB), Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD UK
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Howard AGA, Nguyen AC, Tworig J, Ravisankar P, Singleton EW, Li C, Kotzur G, Waxman JS, Uribe RA. Elevated Hoxb5b Expands Vagal Neural Crest Pool and Blocks Enteric Neuronal Development in Zebrafish. Front Cell Dev Biol 2022; 9:803370. [PMID: 35174164 PMCID: PMC8841348 DOI: 10.3389/fcell.2021.803370] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
Neural crest cells (NCCs) are a migratory, transient, and multipotent stem cell population essential to vertebrate embryonic development, contributing to numerous cell lineages in the adult organism. While great strides have been made in elucidating molecular and cellular events that drive NCC specification, comprehensive knowledge of the genetic factors that orchestrate NCC developmental programs is still far from complete. We discovered that elevated Hoxb5b levels promoted an expansion of zebrafish NCCs, which persisted throughout multiple stages of development. Correspondingly, elevated Hoxb5b also specifically expanded expression domains of the vagal NCC markers foxd3 and phox2bb. Increases in NCCs were most apparent after pulsed ectopic Hoxb5b expression at early developmental stages, rather than later during differentiation stages, as determined using a novel transgenic zebrafish line. The increase in vagal NCCs early in development led to supernumerary Phox2b+ enteric neural progenitors, while leaving many other NCC-derived tissues without an overt phenotype. Surprisingly, these NCC-derived enteric progenitors failed to expand properly into sufficient quantities of enterically fated neurons and stalled in the gut tissue. These results suggest that while Hoxb5b participates in vagal NCC development as a driver of progenitor expansion, the supernumerary, ectopically localized NCC fail to initiate expansion programs in timely fashion in the gut. All together, these data point to a model in which Hoxb5b regulates NCCs both in a tissue specific and temporally restricted manner.
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Affiliation(s)
| | - Aaron C. Nguyen
- BioSciences Department, Rice University, Houston, TX, United States
| | - Joshua Tworig
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Priya Ravisankar
- Molecular Cardiovascular Biology Division, Cincinnati Children’s Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
- Allen Institute of Immunology, Seattle, WA, United States
| | | | - Can Li
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Grayson Kotzur
- BioSciences Department, Rice University, Houston, TX, United States
| | - Joshua S. Waxman
- Molecular Cardiovascular Biology Division, Cincinnati Children’s Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Rosa A. Uribe
- BioSciences Department, Rice University, Houston, TX, United States
- *Correspondence: Rosa A. Uribe,
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Diaz-Cuadros M, Pourquié O, El-Sherif E. Patterning with clocks and genetic cascades: Segmentation and regionalization of vertebrate versus insect body plans. PLoS Genet 2021; 17:e1009812. [PMID: 34648490 PMCID: PMC8516289 DOI: 10.1371/journal.pgen.1009812] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Oscillatory and sequential processes have been implicated in the spatial patterning of many embryonic tissues. For example, molecular clocks delimit segmental boundaries in vertebrates and insects and mediate lateral root formation in plants, whereas sequential gene activities are involved in the specification of regional identities of insect neuroblasts, vertebrate neural tube, vertebrate limb, and insect and vertebrate body axes. These processes take place in various tissues and organisms, and, hence, raise the question of what common themes and strategies they share. In this article, we review 2 processes that rely on the spatial regulation of periodic and sequential gene activities: segmentation and regionalization of the anterior-posterior (AP) axis of animal body plans. We study these processes in species that belong to 2 different phyla: vertebrates and insects. By contrasting 2 different processes (segmentation and regionalization) in species that belong to 2 distantly related phyla (arthropods and vertebrates), we elucidate the deep logic of patterning by oscillatory and sequential gene activities. Furthermore, in some of these organisms (e.g., the fruit fly Drosophila), a mode of AP patterning has evolved that seems not to overtly rely on oscillations or sequential gene activities, providing an opportunity to study the evolution of pattern formation mechanisms.
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Affiliation(s)
- Margarete Diaz-Cuadros
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Pathology, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Olivier Pourquié
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Pathology, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- Harvard Stem Cell Institute, Harvard University, Cambridge, Massachusetts, United States of America
| | - Ezzat El-Sherif
- Division of Developmental Biology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Physical Laws Shape Up HOX Gene Collinearity. J Dev Biol 2021; 9:jdb9020017. [PMID: 34066586 PMCID: PMC8162341 DOI: 10.3390/jdb9020017] [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: 03/15/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 01/15/2023] Open
Abstract
Hox gene collinearity (HGC) is a multi-scalar property of many animal phyla particularly important in embryogenesis. It relates entities and events occurring in Hox clusters inside the chromosome DNA and in embryonic tissues. These two entities differ in linear size by more than four orders of magnitude. HGC is observed as spatial collinearity (SC), where the Hox genes are located in the order (Hox1, Hox2, Hox3 …) along the 3′ to 5′ direction of DNA in the genome and a corresponding sequence of ontogenetic units (E1, E2, E3, …) located along the Anterior—Posterior axis of the embryo. Expression of Hox1 occurs in E1, Hox2 in E2, Hox3 in E3, etc. Besides SC, a temporal collinearity (TC) has been also observed in many vertebrates. According to TC, first Hox1 is expressed in E1; later, Hox2 is expressed in E2, followed by Hox3 in E3, etc. Lately, doubt has been raised about whether TC really exists. A biophysical model (BM) was formulated and tested during the last 20 years. According to BM, physical forces are created which pull the Hox genes one after the other, driving them to a transcription factory domain where they are transcribed. The existing experimental data support this BM description. Symmetry is a physical–mathematical property of matter that was explored in depth by Noether who formulated a ground-breaking theory (NT) that applies to all sizes of matter. NT may be applied to biology in order to explain the origin of HGC in animals developing not only along the A/P axis, but also to animals with circular symmetry.
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Durston AJ. A Tribute to Lewis Wolpert and His Ideas on the 50th Anniversary of the Publication of His Paper 'Positional Information and the Spatial Pattern of Differentiation'. Evidence for a Timing Mechanism for Setting Up the Vertebrate Anterior-Posterior (A-P) Axis. Int J Mol Sci 2020; 21:E2552. [PMID: 32272563 PMCID: PMC7177403 DOI: 10.3390/ijms21072552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 03/30/2020] [Accepted: 04/03/2020] [Indexed: 11/16/2022] Open
Abstract
This article is a tribute to Lewis Wolpert and his ideas on the occasion of the recent 50th anniversary of the publication of his article 'Positional Information and the Spatial Pattern of Differentiation'. This tribute relates to another one of his ideas: his early 'Progress Zone' timing model for limb development. Recent evidence is reviewed showing a mechanism sharing features with this model patterning the main body axis in early vertebrate development. This tribute celebrates the golden era of Developmental Biology.
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Affiliation(s)
- Antony J Durston
- Institute of Biology, University of Leiden, Sylvius Laboratory, Sylviusweg 72, 2333 BE Leiden, The Netherlands
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Durston AJ. Some Questions and Answers About the Role of Hox Temporal Collinearity in Vertebrate Axial Patterning. Front Cell Dev Biol 2019; 7:257. [PMID: 31850338 PMCID: PMC6895010 DOI: 10.3389/fcell.2019.00257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 10/16/2019] [Indexed: 01/02/2023] Open
Abstract
The vertebrate anterior-posterior (A-P = craniocaudal) axis is evidently made by a timing mechanism. Evidence has accumulated that tentatively identifies the A-P timer as being or involving Hox temporal collinearity (TC). Here, I focus on the two current competing models based on this premise. Common features and points of dissent are examined and a common model is distilled from what remains. This is an attempt to make sense of the literature.
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Durston AJ. What are the roles of retinoids, other morphogens, and Hox genes in setting up the vertebrate body axis? Genesis 2019; 57:e23296. [PMID: 31021058 PMCID: PMC6767176 DOI: 10.1002/dvg.23296] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 03/24/2019] [Accepted: 03/29/2019] [Indexed: 01/09/2023]
Abstract
This article is concerned with the roles of retinoids and other known anterior-posterior morphogens in setting up the embryonic vertebrate anterior-posterior axis. The discussion is restricted to the very earliest events in setting up the anterior-posterior axis (from blastula to tailbud stages in Xenopus embryos). In these earliest developmental stages, morphogen concentration gradients are not relevant for setting up this axis. It emerges that at these stages, the core patterning mechanism is timing: BMP-anti BMP mediated time space translation that regulates Hox temporal and spatial collinearities and Hox-Hox auto- and cross- regulation. The known anterior-posterior morphogens and signaling pathways--retinoids, FGF's, Cdx, Wnts, Gdf11 and others--interact with this core mechanism at and after space-time defined "decision points," leading to the separation of distinct axial domains. There are also other roles for signaling pathways. Besides the Hox regulated hindbrain/trunk part of the axis, there is a rostral part (including the anterior part of the head and the extreme anterior domain [EAD]) that appears to be regulated by additional mechanisms. Key aspects of anterior-posterior axial patterning, including: the nature of different phases in early patterning and in the whole process; the specificities of Hox action and of intercellular signaling; and the mechanisms of Hox temporal and spatial collinearities, are discussed in relation to the facts and hypotheses proposed above.
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Abstract
Hox temporal collinearity (TC) is a mysterious feature of embryogenesis. This article is opportune because of a recent challenge to TC’s existence This challenge is examined and the evidence that TC does exist is presented. Its function is discussed. Temporal collinearity is thought to be important because it lays the basis for Hox spatial collinearity and the vertebrate A-P axial pattern. The time-space translation mechanism whereby this occurs is examined.
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Affiliation(s)
- A J Durston
- a Institute of Biology , University of Leiden, Sylvius Laboratory , Leiden , Netherlands
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Durston AJ. Two Tier Hox Collinearity Mediates Vertebrate Axial Patterning. Front Cell Dev Biol 2018; 6:102. [PMID: 30234110 PMCID: PMC6131192 DOI: 10.3389/fcell.2018.00102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/10/2018] [Indexed: 12/04/2022] Open
Abstract
A two tier mechanism mediates Hox collinearity. Besides the familiar collinear chromatin modification within each Hox cluster (nanocollinearity), there is also a macrocollinearity tier. Individual Hox clusters and individual cells are coordinated and synchronized to generate multiscale (macro and nano) collinearity in the early vertebrate embryo. Macro-collinearity is mediated by three non-cell autonomous Hox–Hox interactions. These mediate temporal collinearity in early NOM (non-organizer mesoderm), time space translation where temporal collinearity is translated to spatial collinearity along the early embryo’s main body axis and neural transformation, where Hox expression is copied monospecifically from NOM mesoderm to overlying neurectoderm in the late gastrula. Unlike nanocollinearity, which is Hox cluster restricted, axial macrocollinearity extends into the head and EAD domains, thus covering the whole embryonic anterior-posterior (A-P) axis. EAD: extreme anterior domain, the only A-P axial domain anterior to the head. The whole time space translation mechanism interacts with A-P signaling pathways via “decision points,” separating different domains on the axis.
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Affiliation(s)
- Antony J Durston
- Faculty of Science, Institute of Biology Leiden, Leiden University, Leiden, Netherlands
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Durston AJ, Zhu K. A tribute to D'Arcy Wentworth Thompson: Elucidation of a developmental principle. Bioessays 2017; 39. [PMID: 28699180 DOI: 10.1002/bies.201700088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We show the vertebrate anterior -posterior axis is made by time space translation (TST). 1/ TST of Hox temporal to spatial collinearity makes the trunk part of the axis. 2/TST continues into the head. 3/ TST is mediated by collinear Hox-Hox interactions. 4/ 'Decision points' involving signalling pathways separate axial domains.
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Affiliation(s)
- Antony J Durston
- Sylvius Laboratory, Institute of Biology, University of Leiden, Leiden, The Netherlands
| | - Kongju Zhu
- Sylvius Laboratory, Institute of Biology, University of Leiden, Leiden, The Netherlands
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13
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Abstract
Hox gene collinearity was discovered be Edward B. Lewis in 1978. It consists of the Hox1, Hox2, Hox3 ordering of the Hox genes in the chromosome from the telomeric to the centromeric side of the chromosome. Surprisingly, the spatial activation of the Hox genes in the ontogenetic units of the embryo follows the same ordering along the anterior-posterior embryonic axis. The chromosome microscale differs from the embryo macroscale by 3 to 4 orders of magnitude. The traditional biomolecular mechanisms are not adequate to comprise phenomena at so divergent spatial domains. A Biophysical Model of physical forces was proposed which can bridge the intermediate space and explain the results of genetic engineering experiments. Recent progress in constructing instruments and achieving high resolution imaging (e.g., 3D DNA FISH, STORM etc.) enable the assessment of the geometric structure of the chromatin during the different phases of Hox gene activation. It is found that the mouse HoxD gene cluster is elongated up to 5-6 times during Hox gene transcription. These unexpected findings agree with the BM predictions. It is now possible to measure several physical quantities inside the nucleus during Hox gene activation. New experiments are proposed to test further this model.
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Zhu K, Spaink HP, Durston AJ. Hoxc6 loss of function truncates the main body axis in Xenopus. Cell Cycle 2017; 16:1136-1138. [PMID: 28471288 DOI: 10.1080/15384101.2017.1317415] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Affiliation(s)
- Kongju Zhu
- a Institute of Biology, Leiden University , Leiden , the Netherlands
| | - Herman P Spaink
- a Institute of Biology, Leiden University , Leiden , the Netherlands
| | - Antony J Durston
- a Institute of Biology, Leiden University , Leiden , the Netherlands
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