1
|
Hernandez-Morato I, Koss S, Honzel E, Pitman MJ. Netrin-1 as A neural guidance protein in development and reinnervation of the larynx. Ann Anat 2024; 254:152247. [PMID: 38458575 DOI: 10.1016/j.aanat.2024.152247] [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] [Received: 08/21/2023] [Revised: 02/01/2024] [Accepted: 03/05/2024] [Indexed: 03/10/2024]
Abstract
Neural guidance proteins participate in motor neuron migration, axonal projection, and muscle fiber innervation during development. One of the guidance proteins that participates in axonal pathfinding is Netrin-1. Despite the well-known role of Netrin-1 in embryogenesis of central nervous tissue, it is still unclear how the expression of this guidance protein contributes to primary innervation of the periphery, as well as reinnervation. This is especially true in the larynx where Netrin-1 is upregulated within the intrinsic laryngeal muscles after nerve injury and where blocking of Netrin-1 alters the pattern of reinnervation of the intrinsic laryngeal muscles. Despite this consistent finding, it is unknown how Netrin-1 expression contributes to guidance of the axons towards the larynx. Improved knowledge of Netrin-1's role in nerve regeneration and reinnervation post-injury in comparison to its role in primary innervation during embryological development, may provide insights in the search for therapeutics to treat nerve injury. This paper reviews the known functions of Netrin-1 during the formation of the central nervous system and during cranial nerve primary innervation. It also describes the role of Netrin-1 in the formation of the larynx and during recurrent laryngeal reinnervation following nerve injury in the adult.
Collapse
Affiliation(s)
- Ignacio Hernandez-Morato
- Department of Otolaryngology-Head & Neck Surgery, The Center for Voice and Swallowing, Columbia University College of Physicians and Surgeons, New York, NY, United States; Department of Anatomy and Embryology, School of Medicine, Complutense University of Madrid, Madrid, Madrid, Spain.
| | - Shira Koss
- ENT Associates of Nassau County, Levittown, NY, United States
| | - Emily Honzel
- Department of Otolaryngology-Head & Neck Surgery, The Center for Voice and Swallowing, Columbia University College of Physicians and Surgeons, New York, NY, United States
| | - Michael J Pitman
- Department of Otolaryngology-Head & Neck Surgery, The Center for Voice and Swallowing, Columbia University College of Physicians and Surgeons, New York, NY, United States
| |
Collapse
|
2
|
Telmer CA, Karimi K, Chess MM, Agalakov S, Arshinoff BI, Lotay V, Wang DZ, Chu S, Pells TJ, Vize PD, Hinman VF, Ettensohn CA. Echinobase: a resource to support the echinoderm research community. Genetics 2024; 227:iyae002. [PMID: 38262680 PMCID: PMC11075573 DOI: 10.1093/genetics/iyae002] [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: 11/13/2023] [Accepted: 12/27/2023] [Indexed: 01/25/2024] Open
Abstract
Echinobase (www.echinobase.org) is a model organism knowledgebase serving as a resource for the community that studies echinoderms, a phylum of marine invertebrates that includes sea urchins and sea stars. Echinoderms have been important experimental models for over 100 years and continue to make important contributions to environmental, evolutionary, and developmental studies, including research on developmental gene regulatory networks. As a centralized resource, Echinobase hosts genomes and collects functional genomic data, reagents, literature, and other information for the community. This third-generation site is based on the Xenbase knowledgebase design and utilizes gene-centric pages to minimize the time and effort required to access genomic information. Summary gene pages display gene symbols and names, functional data, links to the JBrowse genome browser, and orthology to other organisms and reagents, and tabs from the Summary gene page contain more detailed information concerning mRNAs, proteins, diseases, and protein-protein interactions. The gene pages also display 1:1 orthologs between the fully supported species Strongylocentrotus purpuratus (purple sea urchin), Lytechinus variegatus (green sea urchin), Patiria miniata (bat star), and Acanthaster planci (crown-of-thorns sea star). JBrowse tracks are available for visualization of functional genomic data from both fully supported species and the partially supported species Anneissia japonica (feather star), Asterias rubens (sugar star), and L. pictus (painted sea urchin). Echinobase serves a vital role by providing researchers with annotated genomes including orthology, functional genomic data aligned to the genomes, and curated reagents and data. The Echinoderm Anatomical Ontology provides a framework for standardizing developmental data across the phylum, and knowledgebase content is formatted to be findable, accessible, interoperable, and reusable by the research community.
Collapse
Affiliation(s)
- Cheryl A Telmer
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Kamran Karimi
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Macie M Chess
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Sergei Agalakov
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Bradley I Arshinoff
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Vaneet Lotay
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Dong Zhuo Wang
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Stanley Chu
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Troy J Pells
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Peter D Vize
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Veronica F Hinman
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Charles A Ettensohn
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| |
Collapse
|
3
|
Wellik DM. Hox genes and patterning the vertebrate body. Curr Top Dev Biol 2024; 159:1-27. [PMID: 38729674 DOI: 10.1016/bs.ctdb.2024.02.011] [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: 05/12/2024]
Abstract
The diversity of vertebrate body plans is dizzying, yet stunning for the many things they have in common. Vertebrates have inhabited virtually every part of the earth from its coldest to warmest climates. They locomote by swimming, flying, walking, slithering, or climbing, or combinations of these behaviors. And they exist in many different sizes, from the smallest of frogs, fish and lizards to giraffes, elephants, and blue whales. Despite these differences, vertebrates follow a remarkably similar blueprint for the establishment of their body plan. Within the relatively small amount of time required to complete gastrulation, the process through which the three germ layers, ectoderm, mesoderm, and endoderm are created, the embryo also generates its body axis and is simultaneously patterned. For the length of this axis, the genes that distinguish the neck from the rib cage or the trunk from the sacrum are the Hox genes. In vertebrates, there was evolutionary pressure to maintain this set of genes in the organism. Over the past decades, much has been learned regarding the regulatory mechanisms that ensure the appropriate expression of these genes along the main body axes. Genetic functions continue to be explored though much has been learned. Much less has been discerned on the identity of co-factors used by Hox proteins for the specificity of transcriptional regulation or what downstream targets and pathways are critical for patterning events, though there are notable exceptions. Current work in the field is demonstrating that Hox genes continue to function in many organs long after directing early patterning events. It is hopeful continued research will shed light on remaining questions regarding mechanisms used by this important and conserved set of transcriptional regulators.
Collapse
Affiliation(s)
- Deneen M Wellik
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, United States.
| |
Collapse
|
4
|
Stewen J, Kruse K, Godoi-Filip AT, Zenia, Jeong HW, Adams S, Berkenfeld F, Stehling M, Red-Horse K, Adams RH, Pitulescu ME. Eph-ephrin signaling couples endothelial cell sorting and arterial specification. Nat Commun 2024; 15:2539. [PMID: 38570531 PMCID: PMC10991410 DOI: 10.1038/s41467-024-46300-0] [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: 03/01/2023] [Accepted: 02/21/2024] [Indexed: 04/05/2024] Open
Abstract
Cell segregation allows the compartmentalization of cells with similar fates during morphogenesis, which can be enhanced by cell fate plasticity in response to local molecular and biomechanical cues. Endothelial tip cells in the growing retina, which lead vessel sprouts, give rise to arterial endothelial cells and thereby mediate arterial growth. Here, we have combined cell type-specific and inducible mouse genetics, flow experiments in vitro, single-cell RNA sequencing and biochemistry to show that the balance between ephrin-B2 and its receptor EphB4 is critical for arterial specification, cell sorting and arteriovenous patterning. At the molecular level, elevated ephrin-B2 function after loss of EphB4 enhances signaling responses by the Notch pathway, VEGF and the transcription factor Dach1, which is influenced by endothelial shear stress. Our findings reveal how Eph-ephrin interactions integrate cell segregation and arteriovenous specification in the vasculature, which has potential relevance for human vascular malformations caused by EPHB4 mutations.
Collapse
Affiliation(s)
- Jonas Stewen
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
| | - Kai Kruse
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
- Bioinformatics Service Unit, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
| | - Anca T Godoi-Filip
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
| | - Zenia
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
| | - Hyun-Woo Jeong
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
- Sequencing Core Facility, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
| | - Susanne Adams
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
| | - Frank Berkenfeld
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
| | - Martin Stehling
- Flow Cytometry Unit, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany
| | - Kristy Red-Horse
- Department of Biology, Stanford University, Stanford, CA, USA
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford, CA, USA
| | - Ralf H Adams
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany.
| | - Mara E Pitulescu
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, D-48149, Münster, Germany.
| |
Collapse
|
5
|
Caiaffa CD, Ambekar YS, Singh M, Lin YL, Wlodarczyk B, Aglyamov SR, Scarcelli G, Larin KV, Finnell RH. Disruption of Fuz in mouse embryos generates hypoplastic hindbrain development and reduced cranial nerve ganglia. Dev Dyn 2024. [PMID: 38501709 DOI: 10.1002/dvdy.702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 02/07/2024] [Accepted: 02/20/2024] [Indexed: 03/20/2024] Open
Abstract
BACKGROUND The brain and spinal cord formation is initiated in the earliest stages of mammalian pregnancy in a highly organized process known as neurulation. Environmental or genetic interferences can impair neurulation, resulting in clinically significant birth defects known collectively as neural tube defects. The Fuz gene encodes a subunit of the CPLANE complex, a macromolecular planar polarity effector required for ciliogenesis. Ablation of Fuz in mouse embryos results in exencephaly and spina bifida, including dysmorphic craniofacial structures due to defective cilia formation and impaired Sonic Hedgehog signaling. RESULTS We demonstrate that knocking Fuz out during embryonic mouse development results in a hypoplastic hindbrain phenotype, displaying abnormal rhombomeres with reduced length and width. This phenotype is associated with persistent reduction of ventral neuroepithelial stiffness in a notochord adjacent area at the level of the rhombomere 5. The formation of cranial and paravertebral ganglia is also impaired in these embryos. CONCLUSIONS This study reveals that hypoplastic hindbrain development, identified by abnormal rhombomere morphology and persistent loss of ventral neuroepithelial stiffness, precedes exencephaly in Fuz ablated murine mutants, indicating that the gene Fuz has a critical function sustaining normal neural tube development and neuronal differentiation.
Collapse
Affiliation(s)
- Carlo Donato Caiaffa
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, Texas, USA
- Department of Pediatrics, Dell Pediatric Research Institute, University of Texas at Austin Dell Medical School, Austin, Texas, USA
| | - Yogeshwari S Ambekar
- Department of Biomedical Engineering, University of Houston, Houston, Texas, USA
| | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, Texas, USA
| | - Ying Linda Lin
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, Texas, USA
| | - Bogdan Wlodarczyk
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, Texas, USA
| | - Salavat R Aglyamov
- Department of Biomedical Engineering, University of Houston, Houston, Texas, USA
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland, USA
| | - Kirill V Larin
- Department of Biomedical Engineering, University of Houston, Houston, Texas, USA
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, USA
| | - Richard H Finnell
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Cellular Biology, Molecular and Human Genetics and Medicine, Baylor College of Medicine, Houston, Texas, USA
| |
Collapse
|
6
|
Bedois AMH, Parker HJ, Price AJ, Morrison JA, Bronner ME, Krumlauf R. Sea lamprey enlightens the origin of the coupling of retinoic acid signaling to vertebrate hindbrain segmentation. Nat Commun 2024; 15:1538. [PMID: 38378737 PMCID: PMC10879103 DOI: 10.1038/s41467-024-45911-x] [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: 07/05/2023] [Accepted: 02/06/2024] [Indexed: 02/22/2024] Open
Abstract
Retinoic acid (RA) is involved in antero-posterior patterning of the chordate body axis and, in jawed vertebrates, has been shown to play a major role at multiple levels of the gene regulatory network (GRN) regulating hindbrain segmentation. Knowing when and how RA became coupled to the core hindbrain GRN is important for understanding how ancient signaling pathways and patterning genes can evolve and generate diversity. Hence, we investigated the link between RA signaling and hindbrain segmentation in the sea lamprey Petromyzon marinus, an important jawless vertebrate model providing clues to decipher ancestral vertebrate features. Combining genomics, gene expression, and functional analyses of major components involved in RA synthesis (Aldh1as) and degradation (Cyp26s), we demonstrate that RA signaling is coupled to hindbrain segmentation in lamprey. Thus, the link between RA signaling and hindbrain segmentation is a pan vertebrate feature of the hindbrain and likely evolved at the base of vertebrates.
Collapse
Affiliation(s)
- Alice M H Bedois
- Stowers Institute for Medical Research, Kansas City, MO, 64110, USA
| | - Hugo J Parker
- Stowers Institute for Medical Research, Kansas City, MO, 64110, USA
| | - Andrew J Price
- Stowers Institute for Medical Research, Kansas City, MO, 64110, USA
| | - Jason A Morrison
- Stowers Institute for Medical Research, Kansas City, MO, 64110, USA
| | - Marianne E Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Robb Krumlauf
- Stowers Institute for Medical Research, Kansas City, MO, 64110, USA.
- Department of Anatomy and Cell Biology, Kansas University Medical Center, Kansas City, MO, 66160, USA.
| |
Collapse
|
7
|
Hutchings C, Nuriel Y, Lazar D, Kohl A, Muir E, Genin O, Cinnamon Y, Benyamini H, Nevo Y, Sela-Donenfeld D. Hindbrain boundaries as niches of neural progenitor and stem cells regulated by the extracellular matrix proteoglycan chondroitin sulphate. Development 2024; 151:dev201934. [PMID: 38251863 PMCID: PMC10911165 DOI: 10.1242/dev.201934] [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: 05/02/2023] [Accepted: 01/12/2024] [Indexed: 01/23/2024]
Abstract
The interplay between neural progenitors and stem cells (NPSCs), and their extracellular matrix (ECM) is a crucial regulatory mechanism that determines their behavior. Nonetheless, how the ECM dictates the state of NPSCs remains elusive. The hindbrain is valuable to examine this relationship, as cells in the ventricular surface of hindbrain boundaries (HBs), which arise between any two neighboring rhombomeres, express the NPSC marker Sox2, while being surrounded with the membrane-bound ECM molecule chondroitin sulphate proteoglycan (CSPG), in chick and mouse embryos. CSPG expression was used to isolate HB Sox2+ cells for RNA-sequencing, revealing their distinguished molecular properties as typical NPSCs, which express known and newly identified genes relating to stem cells, cancer, the matrisome and cell cycle. In contrast, the CSPG- non-HB cells, displayed clear neural-differentiation transcriptome. To address whether CSPG is significant for hindbrain development, its expression was manipulated in vivo and in vitro. CSPG manipulations shifted the stem versus differentiation state of HB cells, evident by their behavior and altered gene expression. These results provide further understanding of the uniqueness of hindbrain boundaries as repetitive pools of NPSCs in-between the rapidly growing rhombomeres, which rely on their microenvironment to maintain their undifferentiated state during development.
Collapse
Affiliation(s)
- Carmel Hutchings
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Yarden Nuriel
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Daniel Lazar
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Ayelet Kohl
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Elizabeth Muir
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 1TN, UK
| | - Olga Genin
- Agricultural Research Organization, Volcani Center, Department of Poultry and Aquaculture Science, Rishon LeTsiyon 7505101, Israel
| | - Yuval Cinnamon
- Agricultural Research Organization, Volcani Center, Department of Poultry and Aquaculture Science, Rishon LeTsiyon 7505101, Israel
| | - Hadar Benyamini
- Info-CORE, Bioinformatics Unit of the I-CORE at the Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Yuval Nevo
- Info-CORE, Bioinformatics Unit of the I-CORE at the Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Dalit Sela-Donenfeld
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| |
Collapse
|
8
|
Senovilla-Ganzo R, García-Moreno F. The Phylotypic Brain of Vertebrates, from Neural Tube Closure to Brain Diversification. BRAIN, BEHAVIOR AND EVOLUTION 2024; 99:45-68. [PMID: 38342091 DOI: 10.1159/000537748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 02/04/2024] [Indexed: 02/13/2024]
Abstract
BACKGROUND The phylotypic or intermediate stages are thought to be the most evolutionary conserved stages throughout embryonic development. The contrast with divergent early and later stages derived from the concept of the evo-devo hourglass model. Nonetheless, this developmental constraint has been studied as a whole embryo process, not at organ level. In this review, we explore brain development to assess the existence of an equivalent brain developmental hourglass. In the specific case of vertebrates, we propose to split the brain developmental stages into: (1) Early: Neurulation, when the neural tube arises after gastrulation. (2) Intermediate: Brain patterning and segmentation, when the neuromere identities are established. (3) Late: Neurogenesis and maturation, the stages when the neurons acquire their functionality. Moreover, we extend this analysis to other chordates brain development to unravel the evolutionary origin of this evo-devo constraint. SUMMARY Based on the existing literature, we hypothesise that a major conservation of the phylotypic brain might be due to the pleiotropy of the inductive regulatory networks, which are predominantly expressed at this stage. In turn, earlier stages such as neurulation are rather mechanical processes, whose regulatory networks seem to adapt to environment or maternal geometries. The later stages are also controlled by inductive regulatory networks, but their effector genes are mostly tissue-specific and functional, allowing diverse developmental programs to generate current brain diversity. Nonetheless, all stages of the hourglass are highly interconnected: divergent neurulation must have a vertebrate shared end product to reproduce the vertebrate phylotypic brain, and the boundaries and transcription factor code established during the highly conserved patterning will set the bauplan for the specialised and diversified adult brain. KEY MESSAGES The vertebrate brain is conserved at phylotypic stages, but the highly conserved mechanisms that occur during these brain mid-development stages (Inducing Regulatory Networks) are also present during other stages. Oppositely, other processes as cell interactions and functional neuronal genes are more diverse and majoritarian in early and late stages of development, respectively. These phenomena create an hourglass of transcriptomic diversity during embryonic development and evolution, with a really conserved bottleneck that set the bauplan for the adult brain around the phylotypic stage.
Collapse
Affiliation(s)
- Rodrigo Senovilla-Ganzo
- Achucarro Basque Center for Neuroscience, Scientific Park of the University of the Basque Country (UPV/EHU), Leioa, Spain
- Department of Neuroscience, Faculty of Medicine and Odontology, UPV/EHU, Leioa, Spain
| | - Fernando García-Moreno
- Achucarro Basque Center for Neuroscience, Scientific Park of the University of the Basque Country (UPV/EHU), Leioa, Spain
- Department of Neuroscience, Faculty of Medicine and Odontology, UPV/EHU, Leioa, Spain
- IKERBASQUE Foundation, Bilbao, Spain
| |
Collapse
|
9
|
Rocha-Martins M. Cell behaviors that pattern developing tissues: the case of the vertebrate nervous system. Curr Top Dev Biol 2023; 159:30-58. [PMID: 38729679 DOI: 10.1016/bs.ctdb.2023.11.003] [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: 05/12/2024]
Abstract
Morphogenesis from cells to tissue gives rise to the complex architectures that make our organs. How cells and their dynamic behavior are translated into functional spatial patterns is only starting to be understood. Recent advances in quantitative imaging revealed that, although highly heterogeneous, cellular behaviors make reproducible tissue patterns. Emerging evidence suggests that mechanisms of cellular coordination, intrinsic variability and plasticity are critical for robust pattern formation. While pattern development shows a high level of fidelity, tissue organization has undergone drastic changes throughout the course of evolution. In addition, alterations in cell behavior, if unregulated, can cause developmental malformations that disrupt function. Therefore, comparative studies of different species and of disease models offer a powerful approach for understanding how novel spatial configurations arise from variations in cell behavior and the fundamentals of successful pattern formation. In this chapter, I dive into the development of the vertebrate nervous system to explore efforts to dissect pattern formation beyond molecules, the emerging core principles and open questions.
Collapse
|
10
|
Božanić Urbančič N, Battelino S, Vozel D. Appropriate Vestibular Stimulation in Children and Adolescents-A Prerequisite for Normal Cognitive, Motor Development and Bodily Homeostasis-A Review. CHILDREN (BASEL, SWITZERLAND) 2023; 11:2. [PMID: 38275423 PMCID: PMC10814320 DOI: 10.3390/children11010002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/10/2023] [Accepted: 12/12/2023] [Indexed: 01/27/2024]
Abstract
The structural development of the vestibular part of the inner ear is completed by birth but its central connections continue to develop until adolescence. Their development is dependent on vestibular stimulation-vestibular experience. Studies have shown that vestibular function, modulated by experience and epigenetic factors, is not solely an instrument for body position regulation, navigation, and stabilization of the head and images but also influences cognition, emotion, the autonomous nervous system and hormones. To emphasize the importance of appropriate vestibular stimulation, we present a literature review of its effect on bodily homeostasis, cognition and emotion.
Collapse
Affiliation(s)
- Nina Božanić Urbančič
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia; (N.B.U.); (S.B.)
- Department of Otorhinolaryngology and Cervicofacial Surgery, University Medical Centre Ljubljana, Zaloška 2, 1000 Ljubljana, Slovenia
| | - Saba Battelino
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia; (N.B.U.); (S.B.)
- Department of Otorhinolaryngology and Cervicofacial Surgery, University Medical Centre Ljubljana, Zaloška 2, 1000 Ljubljana, Slovenia
| | - Domen Vozel
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia; (N.B.U.); (S.B.)
- Department of Otorhinolaryngology and Cervicofacial Surgery, University Medical Centre Ljubljana, Zaloška 2, 1000 Ljubljana, Slovenia
| |
Collapse
|
11
|
Honzel E, Hernandez-Morato I, Joshi A, Pennington-Fitzgerald W, Moayedi Y, Pitman MJ. Temporal Expression of Hox Genes and Phox2b in the Rat Nucleus Ambiguus During Development: Implications on Laryngeal Innervation. Laryngoscope 2023; 133:3462-3471. [PMID: 37350386 PMCID: PMC10907063 DOI: 10.1002/lary.30826] [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: 02/23/2023] [Revised: 06/02/2023] [Accepted: 06/05/2023] [Indexed: 06/24/2023]
Abstract
OBJECTIVES Recurrent laryngeal nerve (RLN) injury results in synkinetic reinnervation and vocal fold paralysis. Investigation of cues expressed in the developing brainstem that influence correct selective targeting of intrinsic laryngeal muscles may elucidate post-injury abnormalities contributing to non-functional reinnervation. Primary targets of interest were Hoxb1 and Hoxb2, members of the Hox family that create overlapping gradients in the developing brain, and their target Phox2b, a transcription factor necessary for cranial nerve branchio- and visceromotoneuron survival. METHODS Rat embryos at developmental days E14, E16, E18, and E20 (4 animals/age) were sectioned for RNA in situ hybridization to detect Hoxb1, Hoxb2, and Phox2b mRNA within the brainstem. Slides were costained with Islet1 antibody for identification of the nucleus ambiguus. Results were confirmed using immunohistochemistry. Sections were imaged on a confocal microscope. RNA and protein expressions were quantified using QuPath. Statistical analyses were performed using R. RESULTS Hoxb1, Hoxb2, and Phox2b expressions varied according to embryologic age. Hoxb1 and Hoxb2 expression peaked at E16, with significant decreases at E18 and E20 (one-way ANOVA p = 0.001 for both). Phox2b expression was highest at E14 and trended downward with increased embryologic age (one-way ANOVA p = 0.005). CONCLUSION Peak expression of Hoxb1 and Hoxb2 is observed at time points when the RLN arrives at the larynx and begins to branch toward individual muscles, positioning these gene products to be involved in cueing laryngeal motoneuron identity and target identification. Higher expression of Phox2b earlier in development suggests a role in laryngeal motoneuron formation. LEVEL OF EVIDENCE NA Laryngoscope, 133:3462-3471, 2023.
Collapse
Affiliation(s)
- Emily Honzel
- Department of Otolaryngology-Head & Neck Surgery, Columbia University College of Physicians and Surgeons, New York, New York, U.S.A
| | - Ignacio Hernandez-Morato
- Department of Otolaryngology-Head & Neck Surgery, Columbia University College of Physicians and Surgeons, New York, New York, U.S.A
| | - Abhinav Joshi
- Department of Otolaryngology-Head & Neck Surgery, Columbia University College of Physicians and Surgeons, New York, New York, U.S.A
| | - William Pennington-Fitzgerald
- Department of Otolaryngology-Head & Neck Surgery, Columbia University College of Physicians and Surgeons, New York, New York, U.S.A
| | - Yalda Moayedi
- Department of Otolaryngology-Head & Neck Surgery, Columbia University College of Physicians and Surgeons, New York, New York, U.S.A
- Department of Neurology, Columbia University, New York, New York, U.S.A
| | - Michael J Pitman
- Department of Otolaryngology-Head & Neck Surgery, Columbia University College of Physicians and Surgeons, New York, New York, U.S.A
- Department of Neurology, Columbia University, New York, New York, U.S.A
| |
Collapse
|
12
|
Masak G, Davidson LA. Constructing the pharyngula: Connecting the primary axial tissues of the head with the posterior axial tissues of the tail. Cells Dev 2023; 176:203866. [PMID: 37394035 PMCID: PMC10756936 DOI: 10.1016/j.cdev.2023.203866] [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: 03/23/2023] [Revised: 06/04/2023] [Accepted: 06/29/2023] [Indexed: 07/04/2023]
Abstract
The pharyngula stage of vertebrate development is characterized by stereotypical arrangement of ectoderm, mesoderm, and neural tissues from the anterior spinal cord to the posterior, yet unformed tail. While early embryologists over-emphasized the similarity between vertebrate embryos at the pharyngula stage, there is clearly a common architecture upon which subsequent developmental programs generate diverse cranial structures and epithelial appendages such as fins, limbs, gills, and tails. The pharyngula stage is preceded by two morphogenetic events: gastrulation and neurulation, which establish common shared structures despite the occurrence of cellular processes that are distinct to each of the species. Even along the body axis of a singular organism, structures with seemingly uniform phenotypic characteristics at the pharyngula stage have been established by different processes. We focus our review on the processes underlying integration of posterior axial tissue formation with the primary axial tissues that creates the structures laid out in the pharyngula. Single cell sequencing and novel gene targeting technologies have provided us with new insights into the differences between the processes that form the anterior and posterior axis, but it is still unclear how these processes are integrated to create a seamless body. We suggest that the primary and posterior axial tissues in vertebrates form through distinct mechanisms and that the transition between these mechanisms occur at different locations along the anterior-posterior axis. Filling gaps that remain in our understanding of this transition could resolve ongoing problems in organoid culture and regeneration.
Collapse
Affiliation(s)
- Geneva Masak
- Integrative Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Lance A Davidson
- Integrative Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA; Department of Developmental Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA; Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| |
Collapse
|
13
|
de Nooij JC, Zampieri N. The making of a proprioceptor: a tale of two identities. Trends Neurosci 2023; 46:1083-1094. [PMID: 37858440 DOI: 10.1016/j.tins.2023.09.008] [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: 06/05/2023] [Revised: 09/26/2023] [Accepted: 09/27/2023] [Indexed: 10/21/2023]
Abstract
Proprioception, the sense of body position in space, has a critical role in the control of posture and movement. Aside from skin and joint receptors, the main sources of proprioceptive information in tetrapods are mechanoreceptive end organs in skeletal muscle: muscle spindles (MSs) and Golgi tendon organs (GTOs). The sensory neurons that innervate these receptors are divided into subtypes that detect discrete aspects of sensory information from muscles with different biomechanical functions. Despite the importance of proprioceptive neurons in motor control, the developmental mechanisms that control the acquisition of their distinct functional properties and positional identity are not yet clear. In this review, we discuss recent findings on the development of mouse proprioceptor subtypes and challenges in defining them at the molecular and functional level.
Collapse
Affiliation(s)
- Joriene C de Nooij
- Department of Neurology, Division of Translational Neurobiology, Vagelos College of Physicians and Surgeons, 650 West 168th Street, New York, NY 10032, USA; Columbia University Motor Neuron Center, Columbia University Medical Center, 630 West 168th Street, New York, NY 10032, USA.
| | - Niccolò Zampieri
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
| |
Collapse
|
14
|
Kim YI, O'Rourke R, Sagerström CG. scMultiome analysis identifies embryonic hindbrain progenitors with mixed rhombomere identities. eLife 2023; 12:e87772. [PMID: 37947350 PMCID: PMC10662952 DOI: 10.7554/elife.87772] [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: 03/16/2023] [Accepted: 11/09/2023] [Indexed: 11/12/2023] Open
Abstract
Rhombomeres serve to position neural progenitors in the embryonic hindbrain, thereby ensuring appropriate neural circuit formation, but the molecular identities of individual rhombomeres and the mechanism whereby they form has not been fully established. Here, we apply scMultiome analysis in zebrafish to molecularly resolve all rhombomeres for the first time. We find that rhombomeres become molecularly distinct between 10hpf (end of gastrulation) and 13hpf (early segmentation). While the embryonic hindbrain transiently contains alternating odd- versus even-type rhombomeres, our scMultiome analyses do not detect extensive odd versus even molecular characteristics in the early hindbrain. Instead, we find that each rhombomere displays a unique gene expression and chromatin profile. Prior to the appearance of distinct rhombomeres, we detect three hindbrain progenitor clusters (PHPDs) that correlate with the earliest visually observed segments in the hindbrain primordium that represent prospective rhombomere r2/r3 (possibly including r1), r4, and r5/r6, respectively. We further find that the PHPDs form in response to Fgf and RA morphogens and that individual PHPD cells co-express markers of multiple mature rhombomeres. We propose that the PHPDs contain mixed-identity progenitors and that their subdivision into individual rhombomeres requires the resolution of mixed transcription and chromatin states.
Collapse
Affiliation(s)
- Yong-Il Kim
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Medical SchoolAuroraUnited States
| | - Rebecca O'Rourke
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Medical SchoolAuroraUnited States
| | - Charles G Sagerström
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Medical SchoolAuroraUnited States
| |
Collapse
|
15
|
Belmonte-Mateos C, Meister L, Pujades C. Hindbrain rhombomere centers harbor a heterogenous population of dividing progenitors which rely on Notch signaling. Front Cell Dev Biol 2023; 11:1268631. [PMID: 38020924 PMCID: PMC10652760 DOI: 10.3389/fcell.2023.1268631] [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: 07/28/2023] [Accepted: 10/11/2023] [Indexed: 12/01/2023] Open
Abstract
Tissue growth and morphogenesis are interrelated processes, whose tight coordination is essential for the production of different cell fates and the timely precise allocation of stem cell capacities. The zebrafish embryonic brainstem, the hindbrain, exemplifies such coupling between spatiotemporal cell diversity acquisition and tissue growth as the neurogenic commitment is differentially distributed over time. Here, we combined cell lineage and in vivo imaging approaches to reveal the emergence of specific cell population properties within the rhombomeres. We studied the molecular identity of hindbrain rhombomere centers and showed that they harbor different progenitor capacities that change over time. By clonal analysis, we revealed that cells within the center of rhombomeres decrease the proliferative capacity to remain mainly in the G1 phase. Proliferating progenitors give rise to neurons by asymmetric and symmetric neurogenic divisions while maintaining the pool of progenitors. The proliferative capacity of these cells differs from their neighbors, and they are delayed in the onset of Notch activity. Through functional studies, we demonstrated that they rely on Notch3 signaling to be maintained as non-committed progenitors. In this study, we show that cells in rhombomere centers, despite the neurogenic asynchrony, might share steps of a similar program with the rhombomere counterparts, to ensure proper tissue growth.
Collapse
|
16
|
Leino SA, Constable SCJ, Streit A, Wilkinson DG. Zbtb16 mediates a switch between Fgf signalling regimes in the developing hindbrain. Development 2023; 150:dev201319. [PMID: 37642135 PMCID: PMC10508701 DOI: 10.1242/dev.201319] [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: 09/24/2022] [Accepted: 08/22/2023] [Indexed: 08/31/2023]
Abstract
Developing tissues are sequentially patterned by extracellular signals that are turned on and off at specific times. In the zebrafish hindbrain, fibroblast growth factor (Fgf) signalling has different roles at different developmental stages: in the early hindbrain, transient Fgf3 and Fgf8 signalling from rhombomere 4 is required for correct segmentation, whereas later, neuronal Fgf20 expression confines neurogenesis to specific spatial domains within each rhombomere. How the switch between these two signalling regimes is coordinated is not known. We present evidence that the Zbtb16 transcription factor is required for this transition to happen in an orderly fashion. Zbtb16 expression is high in the early anterior hindbrain, then gradually upregulated posteriorly and confined to neural progenitors. In mutants lacking functional Zbtb16, fgf3 expression fails to be downregulated and persists until a late stage, resulting in excess and more widespread Fgf signalling during neurogenesis. Accordingly, the spatial pattern of neurogenesis is disrupted in Zbtb16 mutants. Our results reveal how the distinct stage-specific roles of Fgf signalling are coordinated in the zebrafish hindbrain.
Collapse
Affiliation(s)
- Sami A. Leino
- Neural Development Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
- Centre for Craniofacial and Regenerative Biology, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London SE1 1UL, UK
| | - Sean C. J. Constable
- Neural Development Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Andrea Streit
- Centre for Craniofacial and Regenerative Biology, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London SE1 1UL, UK
| | - David G. Wilkinson
- Neural Development Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| |
Collapse
|
17
|
Caiaffa CD, Ambekar YS, Singh M, Lin YL, Wlodarczyk B, Aglyamov SR, Scarcelli G, Larin KV, Finnell R. Disruption of Fuz in mouse embryos generates hypoplastic hindbrain development and reduced cranial nerve ganglia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.04.552068. [PMID: 37577618 PMCID: PMC10418252 DOI: 10.1101/2023.08.04.552068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
The formation of the brain and spinal cord is initiated in the earliest stages of mammalian pregnancy in a highly organized process known as neurulation. Convergent and extension movements transforms a flat sheet of ectodermal cells into a narrow and elongated line of neuroepithelia, while a major source of Sonic Hedgehog signaling from the notochord induces the overlying neuroepithelial cells to form two apposed neural folds. Afterward, neural tube closure occurs by synchronized coordination of the surface ectoderm and adjacent neuroepithelial walls at specific axial regions known as neuropores. Environmental or genetic interferences can impair neurulation resulting in neural tube defects. The Fuz gene encodes a subunit of the CPLANE complex, which is a macromolecular planar polarity effector required for ciliogenesis. Ablation of Fuz in mouse embryos results in exencephaly and spina bifida, including dysmorphic craniofacial structures due to defective cilia formation and impaired Sonic Hedgehog signaling. In this work, we demonstrate that knocking Fuz out during embryonic mouse development results in a hypoplastic hindbrain phenotype, displaying abnormal rhombomeres with reduced length and width. This phenotype is associated with persistent loss of ventral neuroepithelial stiffness, in a notochord adjacent area at the level of the rhombomere 5, preceding the development of exencephaly in Fuz ablated mutants. The formation of cranial and paravertebral ganglia is also impaired in these embryos, indicating that Fuz has a critical function sustaining normal neural tube development and neuronal differentiation. SIGNIFICANCE STATEMENT Neural tube defects (NTDs) are a common cause of disability in children, representing the second most common congenital structural malformation in humans following only congenital cardiovascular malformations. NTDs affect approximately 1 to 2 pregnancies per 1000 births every year worldwide, when the mechanical forces folding the neural plate fails to close at specific neuropores located anteriorly (cranial) or posteriorly (caudal) along the neural tube, in a process known as neurulation, which happens throughout the third and fourth weeks of human pregnancy.
Collapse
|
18
|
Bedois AMH, Parker HJ, Bronner ME, Krumlauf R. Sea lamprey enlightens the origin of the coupling of retinoic acid signaling to vertebrate hindbrain segmentation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.07.548143. [PMID: 37461675 PMCID: PMC10350081 DOI: 10.1101/2023.07.07.548143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Retinoic acid (RA) is involved in antero-posterior patterning of the chordate body axis and, in jawed vertebrates, has been shown to play a major role at multiple levels of the gene regulatory network (GRN) regulating hindbrain segmentation. Knowing when and how RA became coupled to the core hindbrain GRN is important for understanding how ancient signaling pathways and patterning genes can evolve and generate diversity. Hence, we investigated the link between RA signaling and hindbrain segmentation in the sea lamprey Petromyzon marinus, an important jawless vertebrate model providing clues to decipher ancestral vertebrate features. Combining genomics, gene expression, and functional analyses of major components involved in RA synthesis (Aldh1as) and degradation (Cyp26s), we demonstrate that RA signaling is coupled to hindbrain segmentation in lamprey. Thus, the link between RA signaling and hindbrain segmentation is a pan vertebrate feature of the hindbrain and likely evolved at the base of vertebrates.
Collapse
Affiliation(s)
- Alice M. H. Bedois
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | - Hugo J. Parker
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | - Marianne E. Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Robb Krumlauf
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
- Department of Anatomy and Cell Biology, Kansas University Medical Center, Kansas City, Kansas 66160, USA
| |
Collapse
|
19
|
Afzal Z, Lange JJ, Nolte C, McKinney S, Wood C, Paulson A, De Kumar B, Unruh J, Slaughter BD, Krumlauf R. Shared retinoic acid responsive enhancers coordinately regulate nascent transcription of Hoxb coding and non-coding RNAs in the developing mouse neural tube. Development 2023; 150:dev201259. [PMID: 37102683 PMCID: PMC10233718 DOI: 10.1242/dev.201259] [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: 09/01/2022] [Accepted: 04/19/2023] [Indexed: 04/28/2023]
Abstract
Signaling pathways regulate the patterns of Hox gene expression that underlie their functions in the specification of axial identity. Little is known about the properties of cis-regulatory elements and underlying transcriptional mechanisms that integrate graded signaling inputs to coordinately control Hox expression. Here, we optimized a single molecule fluorescent in situ hybridization (smFISH) technique with probes spanning introns to evaluate how three shared retinoic acid response element (RARE)-dependent enhancers in the Hoxb cluster regulate patterns of nascent transcription in vivo at the level of single cells in wild-type and mutant embryos. We predominately detect nascent transcription of only a single Hoxb gene in each cell, with no evidence for simultaneous co-transcriptional coupling of all or specific subsets of genes. Single and/or compound RARE mutations indicate that each enhancer differentially impacts global and local patterns of nascent transcription, suggesting that selectivity and competitive interactions between these enhancers is important to robustly maintain the proper levels and patterns of nascent Hoxb transcription. This implies that rapid and dynamic regulatory interactions potentiate transcription of genes through combined inputs from these enhancers in coordinating the retinoic acid response.
Collapse
Affiliation(s)
- Zainab Afzal
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Anatomy and Cell Biology Department, Kansas University Medical Center, Kansas City, KS 66160, USA
| | - Jeffrey J. Lange
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Christof Nolte
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Sean McKinney
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Christopher Wood
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Ariel Paulson
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Bony De Kumar
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Jay Unruh
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | | | - Robb Krumlauf
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Anatomy and Cell Biology Department, Kansas University Medical Center, Kansas City, KS 66160, USA
| |
Collapse
|
20
|
Kim YI, O’Rourke R, Sagerström CG. scMultiome analysis identifies embryonic hindbrain progenitors with mixed rhombomere identities. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.27.525932. [PMID: 36747868 PMCID: PMC9900950 DOI: 10.1101/2023.01.27.525932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Rhombomeres serve to position neural progenitors in the embryonic hindbrain, thereby ensuring appropriate neural circuit formation, but the molecular identities of individual rhombomeres and the mechanism whereby they form have not been fully established. Here we apply scMultiome analysis in zebrafish to molecularly resolve all rhombomeres for the first time. We find that rhombomeres become molecularly distinct between 10hpf (end of gastrulation) and 13hpf (early segmentation). While the mature hindbrain consists of alternating odd- versus even-type rhombomeres, our scMultiome analyses do not detect extensive odd versus even characteristics in the early hindbrain. Instead, we find that each rhombomere displays a unique gene expression and chromatin profile. Prior to the appearance of distinct rhombomeres, we detect three hindbrain progenitor clusters (PHPDs) that correlate with the earliest visually observed segments in the hindbrain primordium and that represent prospective rhombomere r2/r3 (possibly including r1), r4 and r5/r6, respectively. We further find that the PHPDs form in response to Fgf and RA morphogens and that individual PHPD cells co-express markers of multiple mature rhombomeres. We propose that the PHPDs contain mixed-identity progenitors and that their subdivision into individual mature rhombomeres requires resolution of mixed transcription and chromatin states.
Collapse
Affiliation(s)
| | | | - Charles G. Sagerström
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Medical School, 12801 E. 17th Avenue, Aurora, CO 80045
| |
Collapse
|
21
|
Abstract
Hox genes encode evolutionarily conserved transcription factors that are essential for the proper development of bilaterian organisms. Hox genes are unique because they are spatially and temporally regulated during development in a manner that is dictated by their tightly linked genomic organization. Although their genetic function during embryonic development has been interrogated, less is known about how these transcription factors regulate downstream genes to direct morphogenetic events. Moreover, the continued expression and function of Hox genes at postnatal and adult stages highlights crucial roles for these genes throughout the life of an organism. Here, we provide an overview of Hox genes, highlighting their evolutionary history, their unique genomic organization and how this impacts the regulation of their expression, what is known about their protein structure, and their deployment in development and beyond.
Collapse
Affiliation(s)
- Katharine A. Hubert
- Program in Genetics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Deneen M. Wellik
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| |
Collapse
|
22
|
Beine Z, Wang Z, Tsoulfas P, Blackmore MG. Single Nuclei Analyses Reveal Transcriptional Profiles and Marker Genes for Diverse Supraspinal Populations. J Neurosci 2022; 42:8780-8794. [PMID: 36202615 PMCID: PMC9698772 DOI: 10.1523/jneurosci.1197-22.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 09/07/2022] [Accepted: 09/29/2022] [Indexed: 01/18/2023] Open
Abstract
The mammalian brain contains numerous neurons distributed across forebrain, midbrain, and hindbrain that project axons to the lower spinal cord and work in concert to control movement and achieve homeostasis. Extensive work has mapped the anatomic location of supraspinal cell types and continues to establish specific physiological functions. The patterns of gene expression that typify and distinguish these disparate populations, however, are mostly unknown. Here, using adult mice of mixed sex, we combined retrograde labeling of supraspinal cell nuclei with fluorescence-activated nuclei sorting and single-nuclei RNA sequencing analyses to transcriptionally profile neurons that project axons from the brain to lumbar spinal cord. We identified 14 transcriptionally distinct cell types and used a combination of established and newly identified marker genes to assign an anatomic location to each. To validate the putative marker genes, we visualized selected transcripts and confirmed selective expression within lumbar-projecting neurons in discrete supraspinal regions. Finally, we illustrate the potential utility of these data by examining the expression of transcription factors that distinguish different supraspinal cell types and by surveying the expression of receptors for growth and guidance cues that may be present in the spinal cord. Collectively, these data establish transcriptional differences between anatomically defined supraspinal populations, identify a new set of marker genes of use in future experiments, and provide insight into potential differences in cellular and physiological activity across the supraspinal connectome.SIGNIFICANCE STATEMENT The brain communicates with the body through a wide variety of neuronal populations with distinct functions and differential sensitivity to damage and disease. We have used single-nuclei RNA sequencing technology to distinguish patterns of gene expression within a diverse set of neurons that project axons from the mouse brain to the lumbar spinal cord. The results reveal transcriptional differences between populations previously defined on the basis of anatomy, provide new marker genes to facilitate rapid identification of cell type in future work, and suggest distinct responsiveness of different supraspinal populations to external growth and guidance cues.
Collapse
Affiliation(s)
- Zachary Beine
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53201
| | - Zimei Wang
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53201
| | - Pantelis Tsoulfas
- Department of Neurological Surgery, Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Murray G Blackmore
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53201
| |
Collapse
|
23
|
Bolkhovitinov L, Weselman BT, Shaw GA, Dong C, Giribhattanavar J, Saha MS. Tissue Rotation of the Xenopus Anterior-Posterior Neural Axis Reveals Profound but Transient Plasticity at the Mid-Gastrula Stage. J Dev Biol 2022; 10:38. [PMID: 36135371 PMCID: PMC9503425 DOI: 10.3390/jdb10030038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/02/2022] [Accepted: 09/06/2022] [Indexed: 11/17/2022] Open
Abstract
The establishment of anterior-posterior (AP) regional identity is an essential step in the appropriate development of the vertebrate central nervous system. An important aspect of AP neural axis formation is the inherent plasticity that allows developing cells to respond to and recover from the various perturbations that embryos continually face during the course of development. While the mechanisms governing the regionalization of the nervous system have been extensively studied, relatively less is known about the nature and limits of early neural plasticity of the anterior-posterior neural axis. This study aims to characterize the degree of neural axis plasticity in Xenopus laevis by investigating the response of embryos to a 180-degree rotation of their AP neural axis during gastrula stages by assessing the expression of regional marker genes using in situ hybridization. Our results reveal the presence of a narrow window of time between the mid- and late gastrula stage, during which embryos are able undergo significant recovery following a 180-degree rotation of their neural axis and eventually express appropriate regional marker genes including Otx, Engrailed, and Krox. By the late gastrula stage, embryos show misregulation of regional marker genes following neural axis rotation, suggesting that this profound axial plasticity is a transient phenomenon that is lost by late gastrula stages.
Collapse
Affiliation(s)
- Lyuba Bolkhovitinov
- Department of Molecular Biology, Massachusetts General Hospital, Harvard University, Boston, MA 02114, USA
| | - Bryan T. Weselman
- School of Medicine, Georgetown University, Washington, DC 20007, USA
| | - Gladys A. Shaw
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - Chen Dong
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | - Margaret S. Saha
- Department of Biology, College of William and Mary, Williamsburg, VA 23185, USA
| |
Collapse
|
24
|
Ye Q, Bhojwani A, Hu JK. Understanding the development of oral epithelial organs through single cell transcriptomic analysis. Development 2022; 149:dev200539. [PMID: 35831953 PMCID: PMC9481975 DOI: 10.1242/dev.200539] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 07/07/2022] [Indexed: 01/29/2023]
Abstract
During craniofacial development, the oral epithelium begins as a morphologically homogeneous tissue that gives rise to locally complex structures, including the teeth, salivary glands and taste buds. How the epithelium is initially patterned and specified to generate diverse cell types remains largely unknown. To elucidate the genetic programs that direct the formation of distinct oral epithelial populations, we mapped the transcriptional landscape of embryonic day 12 mouse mandibular epithelia at single cell resolution. Our analysis identified key transcription factors and gene regulatory networks that define different epithelial cell types. By examining the spatiotemporal patterning process along the oral-aboral axis, our results propose a model in which the dental field is progressively confined to its position by the formation of the aboral epithelium anteriorly and the non-dental oral epithelium posteriorly. Using our data, we also identified Ntrk2 as a proliferation driver in the forming incisor, contributing to its invagination. Together, our results provide a detailed transcriptional atlas of the embryonic mandibular epithelium, and unveil new genetic markers and regulators that are present during the specification of various oral epithelial structures.
Collapse
Affiliation(s)
- Qianlin Ye
- School of Dentistry, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Arshia Bhojwani
- School of Dentistry, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Jimmy K. Hu
- School of Dentistry, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| |
Collapse
|
25
|
Vogenstahl J, Parrilla M, Acker-Palmer A, Segarra M. Vascular Regulation of Developmental Neurogenesis. Front Cell Dev Biol 2022; 10:890852. [PMID: 35573692 PMCID: PMC9099230 DOI: 10.3389/fcell.2022.890852] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Evolutionary studies indicate that the nervous system evolved prior to the vascular system, but the increasing complexity of organisms prompted the vascular system to emerge in order to meet the growing demand for oxygen and nutrient supply. In recent years, it has become apparent that the symbiotic communication between the nervous and the vascular systems goes beyond the exclusive covering of the demands on nutrients and oxygen carried by blood vessels. Indeed, this active interplay between both systems is crucial during the development of the central nervous system (CNS). Several neural-derived signals that initiate and regulate the vascularization of the CNS have been described, however less is known about the vascular signals that orchestrate the development of the CNS cytoarchitecture. Here, we focus on reviewing the effects of blood vessels in the process of neurogenesis during CNS development in vertebrates. In mammals, we describe the spatiotemporal features of vascular-driven neurogenesis in two brain regions that exhibit different neurogenic complexity in their germinal zone, the hindbrain and the forebrain.
Collapse
Affiliation(s)
- Johanna Vogenstahl
- Neuro and Vascular Guidance Group, Buchmann Institute for Molecular Life Sciences (BMLS) and Institute of Cell Biology and Neuroscience, Frankfurt am Main, Germany
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | - Marta Parrilla
- Neuro and Vascular Guidance Group, Buchmann Institute for Molecular Life Sciences (BMLS) and Institute of Cell Biology and Neuroscience, Frankfurt am Main, Germany
| | - Amparo Acker-Palmer
- Neuro and Vascular Guidance Group, Buchmann Institute for Molecular Life Sciences (BMLS) and Institute of Cell Biology and Neuroscience, Frankfurt am Main, Germany
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
- Cardio-Pulmonary Institute (CPI), Frankfurt am Main, Germany
- *Correspondence: Amparo Acker-Palmer, ; Marta Segarra,
| | - Marta Segarra
- Neuro and Vascular Guidance Group, Buchmann Institute for Molecular Life Sciences (BMLS) and Institute of Cell Biology and Neuroscience, Frankfurt am Main, Germany
- Cardio-Pulmonary Institute (CPI), Frankfurt am Main, Germany
- *Correspondence: Amparo Acker-Palmer, ; Marta Segarra,
| |
Collapse
|
26
|
Abstract
The EPH receptor tyrosine kinases and their signaling partners, the EPHRINS, comprise a large class of cell signaling molecules that plays diverse roles in development. As cell membrane-anchored signaling molecules, they regulate cellular organization by modulating the strength of cellular contacts, usually by impacting the actin cytoskeleton or cell adhesion programs. Through these cellular functions, EPH/EPHRIN signaling often regulates tissue shape. Indeed, recent evidence indicates that this signaling family is ancient and associated with the origin of multicellularity. Though extensively studied, our understanding of the signaling mechanisms employed by this large family of signaling proteins remains patchwork, and a truly "canonical" EPH/EPHRIN signal transduction pathway is not known and may not exist. Instead, several foundational evolutionarily conserved mechanisms are overlaid by a myriad of tissue -specific functions, though common themes emerge from these as well. Here, I review recent advances and the related contexts that have provided new understanding of the conserved and varied molecular and cellular mechanisms employed by EPH/EPHRIN signaling during development.
Collapse
Affiliation(s)
- Jeffrey O Bush
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, CA, United States; Program in Craniofacial Biology, University of California San Francisco, San Francisco, CA, United States; Institute for Human Genetics, University of California San Francisco, San Francisco, CA, United States; Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA, United States.
| |
Collapse
|
27
|
Needham J, Metzis V. Heads or tails: Making the spinal cord. Dev Biol 2022; 485:80-92. [DOI: 10.1016/j.ydbio.2022.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/15/2021] [Accepted: 03/02/2022] [Indexed: 12/14/2022]
|
28
|
Diaz C, Glover JC. The Vestibular Column in the Mouse: A Rhombomeric Perspective. Front Neuroanat 2022; 15:806815. [PMID: 35173589 PMCID: PMC8842660 DOI: 10.3389/fnana.2021.806815] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/20/2021] [Indexed: 11/30/2022] Open
Abstract
The vestibular column is located in the hindbrain between the sensory auditory (dorsal) and trigeminal (ventral) columns, spanning rhombomeres r1 (or r2) to r9. It contains the vestibular nuclear complex that receives sensory innervation from the labyrinthine end organs in the inner ear. Gene expression studies and experimental manipulations of developmental genes, particularly Hox genes and other developmental patterning genes, are providing insight into the morphological and functional organization of the vestibular nuclear complex, particularly from a segmental standpoint. Here, we will review studies of the classical vestibular nuclei and of vestibular projection neurons that innervate distinct targets in relation to individual rhombomeres and the expression of specific genes. Studies in different species have demonstrated that the vestibular complex is organized into a hodological mosaic that relates axon trajectory and target to specific hindbrain rhombomeres and intrarhombomeric domains, with a molecular underpinning in the form of transcription factor signatures, which has been highly conserved during the evolution of the vertebrate lineage.
Collapse
Affiliation(s)
- Carmen Diaz
- Department of Medical Sciences, School of Medicine and Institute for Research in Neurological Disabilities, University of Castilla-La Mancha, Albacete, Spain
- *Correspondence: Carmen Diaz,
| | - Joel C. Glover
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Joel C. Glover,
| |
Collapse
|
29
|
Transcriptional Regulation and Implications for Controlling Hox Gene Expression. J Dev Biol 2022; 10:jdb10010004. [PMID: 35076545 PMCID: PMC8788451 DOI: 10.3390/jdb10010004] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 02/06/2023] Open
Abstract
Hox genes play key roles in axial patterning and regulating the regional identity of cells and tissues in a wide variety of animals from invertebrates to vertebrates. Nested domains of Hox expression generate a combinatorial code that provides a molecular framework for specifying the properties of tissues along the A–P axis. Hence, it is important to understand the regulatory mechanisms that coordinately control the precise patterns of the transcription of clustered Hox genes required for their roles in development. New insights are emerging about the dynamics and molecular mechanisms governing transcriptional regulation, and there is interest in understanding how these may play a role in contributing to the regulation of the expression of the clustered Hox genes. In this review, we summarize some of the recent findings, ideas and emerging mechanisms underlying the regulation of transcription in general and consider how they may be relevant to understanding the transcriptional regulation of Hox genes.
Collapse
|
30
|
Abstract
The Tabula Gallus is a proposed project that aims to create a map of every cell type in the chicken body and chick embryos. Chickens (Gallus gallus) are one of the most recognized model animals that recapitulate the development and physiology of mammals. The Tabula Gallus will generate a compendium of single-cell transcriptome data from Gallus gallus, characterize each cell type, and provide tools for the study of the biology of this species, similar to other ongoing cell atlas projects (Tabula Muris and Tabula Sapiens/Human Cell Atlas for mice and humans, respectively). The Tabula Gallus will potentially become an international collaboration between many researchers. This project will be useful for the basic scientific study of Gallus gallus and other birds (e.g., cell biology, molecular biology, developmental biology, neuroscience, physiology, oncology, virology, behavior, ecology, and evolution). It will eventually be beneficial for a better understanding of human health and diseases.
Collapse
|
31
|
García-Guillén IM, Martínez-de-la-Torre M, Puelles L, Aroca P, Marín F. Molecular Segmentation of the Spinal Trigeminal Nucleus in the Adult Mouse Brain. Front Neuroanat 2021; 15:785840. [PMID: 34955765 PMCID: PMC8702626 DOI: 10.3389/fnana.2021.785840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 11/22/2021] [Indexed: 11/13/2022] Open
Abstract
The trigeminal column is a hindbrain structure formed by second order sensory neurons that receive afferences from trigeminal primary (ganglionic) nerve fibers. Classical studies subdivide it into the principal sensory trigeminal nucleus located next to the pontine nerve root, and the spinal trigeminal nucleus which in turn consists of oral, interpolar and caudal subnuclei. On the other hand, according to the prosomeric model, this column would be subdivided into segmental units derived from respective rhombomeres. Experimental studies have mapped the principal sensory trigeminal nucleus to pontine rhombomeres (r) r2-r3 in the mouse. The spinal trigeminal nucleus emerges as a plurisegmental formation covering several rhombomeres (r4 to r11 in mice) across pontine, retropontine and medullary hindbrain regions. In the present work we reexamined the issue of rhombomeric vs. classical subdivisions of this column. To this end, we analyzed its subdivisions in an AZIN2-lacZ transgenic mouse, known as a reference model for hindbrain topography, together with transgenic reporter lines for trigeminal fibers. We screened as well for genes differentially expressed along the axial dimension of this structure in the adult and juvenile mouse brain. This analysis yielded genes from multiple functional families that display transverse domains fitting the mentioned rhombomeric map. The spinal trigeminal nucleus thus represents a plurisegmental structure with a series of distinct neuromeric units having unique combinatorial molecular profiles.
Collapse
Affiliation(s)
- Isabel M García-Guillén
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", Biomedical Research Institute of Murcia (IMIB-Arrixaca), University of Murcia, Murcia, Spain
| | - Margaret Martínez-de-la-Torre
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", Biomedical Research Institute of Murcia (IMIB-Arrixaca), University of Murcia, Murcia, Spain
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", Biomedical Research Institute of Murcia (IMIB-Arrixaca), University of Murcia, Murcia, Spain
| | - Pilar Aroca
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", Biomedical Research Institute of Murcia (IMIB-Arrixaca), University of Murcia, Murcia, Spain
| | - Faustino Marín
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", Biomedical Research Institute of Murcia (IMIB-Arrixaca), University of Murcia, Murcia, Spain
| |
Collapse
|
32
|
Wilkinson DG. Interplay of Eph-Ephrin Signalling and Cadherin Function in Cell Segregation and Boundary Formation. Front Cell Dev Biol 2021; 9:784039. [PMID: 34869386 PMCID: PMC8633894 DOI: 10.3389/fcell.2021.784039] [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: 09/27/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
The segregation of distinct cell populations to form sharp boundaries is crucial for stabilising tissue organisation, for example during hindbrain segmentation in craniofacial development. Two types of mechanisms have been found to underlie cell segregation: differential adhesion mediated by cadherins, and Eph receptor and ephrin signalling at the heterotypic interface which regulates cell adhesion, cortical tension and repulsion. An interplay occurs between these mechanisms since cadherins have been found to contribute to Eph-ephrin-mediated cell segregation. This may reflect that Eph receptor activation acts through multiple pathways to decrease cadherin-mediated adhesion which can drive cell segregation. However, Eph receptors mainly drive cell segregation through increased heterotypic tension or repulsion. Cadherins contribute to cell segregation by antagonising homotypic tension within each cell population. This suppression of homotypic tension increases the difference with heterotypic tension triggered by Eph receptor activation, and it is this differential tension that drives cell segregation and border sharpening.
Collapse
|