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Barone V, Tagua A, Román JÁAS, Hamdoun A, Garrido-García J, Lyons DC, Escudero LM. Local and global changes in cell density induce reorganisation of 3D packing in a proliferating epithelium. Development 2024; 151:dev202362. [PMID: 38619327 PMCID: PMC11112164 DOI: 10.1242/dev.202362] [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: 09/15/2023] [Accepted: 03/28/2024] [Indexed: 04/16/2024]
Abstract
Tissue morphogenesis is intimately linked to the changes in shape and organisation of individual cells. In curved epithelia, cells can intercalate along their own apicobasal axes, adopting a shape named 'scutoid' that allows energy minimization in the tissue. Although several geometric and biophysical factors have been associated with this 3D reorganisation, the dynamic changes underlying scutoid formation in 3D epithelial packing remain poorly understood. Here, we use live imaging of the sea star embryo coupled with deep learning-based segmentation to dissect the relative contributions of cell density, tissue compaction and cell proliferation on epithelial architecture. We find that tissue compaction, which naturally occurs in the embryo, is necessary for the appearance of scutoids. Physical compression experiments identify cell density as the factor promoting scutoid formation at a global level. Finally, the comparison of the developing embryo with computational models indicates that the increase in the proportion of scutoids is directly associated with cell divisions. Our results suggest that apico-basal intercalations appearing immediately after mitosis may help accommodate the new cells within the tissue. We propose that proliferation in a compact epithelium induces 3D cell rearrangements during development.
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Affiliation(s)
- Vanessa Barone
- Center for Marine Biotechnology and Biomedicine, University of California San Diego, La Jolla, CA 92093, USA
- Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA 93950, USA
| | - Antonio Tagua
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla, 41013 Seville, Spain
| | - Jesus Á. Andrés-San Román
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla, 41013 Seville, Spain
| | - Amro Hamdoun
- Center for Marine Biotechnology and Biomedicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Juan Garrido-García
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla, 41013 Seville, Spain
| | - Deirdre C. Lyons
- Center for Marine Biotechnology and Biomedicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Luis M. Escudero
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla, 41013 Seville, Spain
- Biomedical Network Research Centre on Neurodegenerative Diseases (CIBERNED), 28029 Madrid, Spain
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Barone V, Tagua A, Andrés-San Román JÁ, Hamdoun A, Garrido-García J, Lyons DC, Escudero LM. Local and global changes in cell density induce reorganisation of 3D packing in a proliferating epithelium. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.08.579268. [PMID: 38370815 PMCID: PMC10871321 DOI: 10.1101/2024.02.08.579268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Tissue morphogenesis is intimately linked to the changes in shape and organisation of individual cells. In curved epithelia, cells can intercalate along their own apicobasal axes adopting a shape named "scutoid" that allows energy minimization in the tissue. Although several geometric and biophysical factors have been associated with this 3D reorganisation, the dynamic changes underlying scutoid formation in 3D epithelial packing remain poorly understood. Here we use live-imaging of the sea star embryo coupled with deep learning-based segmentation, to dissect the relative contributions of cell density, tissue compaction, and cell proliferation on epithelial architecture. We find that tissue compaction, which naturally occurs in the embryo, is necessary for the appearance of scutoids. Physical compression experiments identify cell density as the factor promoting scutoid formation at a global level. Finally, the comparison of the developing embryo with computational models indicates that the increase in the proportion of scutoids is directly associated with cell divisions. Our results suggest that apico-basal intercalations appearing just after mitosis may help accommodate the new cells within the tissue. We propose that proliferation in a compact epithelium induces 3D cell rearrangements during development.
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Affiliation(s)
- Vanessa Barone
- Center for Marine Biotechnology and Biomedicine, University of California San Diego, La Jolla, CA, 92093, USA
- Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA, 93950, USA
| | - Antonio Tagua
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla. 41013 Seville, Spain
| | - Jesus Á Andrés-San Román
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla. 41013 Seville, Spain
| | - Amro Hamdoun
- Center for Marine Biotechnology and Biomedicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Juan Garrido-García
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla. 41013 Seville, Spain
| | - Deirdre C Lyons
- Center for Marine Biotechnology and Biomedicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Luis M Escudero
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla. 41013 Seville, Spain
- Biomedical Network Research Centre on Neurodegenerative Diseases (CIBERNED), 28029 Madrid, Spain
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Barone V, Lyons DC. Live imaging of echinoderm embryos to illuminate evo-devo. Front Cell Dev Biol 2022; 10:1007775. [PMID: 36187474 PMCID: PMC9521734 DOI: 10.3389/fcell.2022.1007775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022] Open
Abstract
Echinoderm embryos have been model systems for cell and developmental biology for over 150 years, in good part because of their optical clarity. Discoveries that shaped our understanding of fertilization, cell division and cell differentiation were only possible because of the transparency of sea urchin eggs and embryos, which allowed direct observations of intracellular structures. More recently, live imaging of sea urchin embryos, coupled with fluorescence microscopy, has proven pivotal to uncovering mechanisms of epithelial to mesenchymal transition, cell migration and gastrulation. However, live imaging has mainly been performed on sea urchin embryos, while echinoderms include numerous experimentally tractable species that present interesting variation in key aspects of morphogenesis, including differences in embryo compaction and mechanisms of blastula formation. The study of such variation would allow us not only to understand how tissues are formed in echinoderms, but also to identify which changes in cell shape, cell-matrix and cell-cell contact formation are more likely to result in evolution of new embryonic shapes. Here we argue that adapting live imaging techniques to more echinoderm species will be fundamental to exploit such an evolutionary approach to the study of morphogenesis, as it will allow measuring differences in dynamic cellular behaviors - such as changes in cell shape and cell adhesion - between species. We briefly review existing methods for live imaging of echinoderm embryos and describe in detail how we adapted those methods to allow long-term live imaging of several species, namely the sea urchin Lytechinus pictus and the sea stars Patiria miniata and Patiriella regularis. We outline procedures to successfully label, mount and image early embryos for 10–16 h, from cleavage stages to early blastula. We show that data obtained with these methods allows 3D segmentation and tracking of individual cells over time, the first step to analyze how cell shape and cell contact differ among species. The methods presented here can be easily adopted by most cell and developmental biology laboratories and adapted to successfully image early embryos of additional species, therefore broadening our understanding of the evolution of morphogenesis.
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Lineage tracing shows that cell size asymmetries predict the dorsoventral axis in the sea star embryo. BMC Biol 2022; 20:179. [PMID: 35971116 PMCID: PMC9380389 DOI: 10.1186/s12915-022-01359-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 06/23/2022] [Indexed: 11/21/2022] Open
Abstract
Background Cell size asymmetries are often linked to cell fate decisions, due to cell volumes and cell fate determinants being unequally partitioned during asymmetric cell divisions. A clear example is found in the sea urchin embryo, where a characteristic and obvious unequal 4th cleavage generates micromeres, which are necessary for mesendoderm cell fate specification. Unlike sea urchin development, sea star development is generally thought to have only equal cleavage. However, subtle cell size asymmetries can be observed in sea star embryos; whether those cell size asymmetries are consistently produced during sea star development and if they are involved in cell fate decisions remains unknown. Results Using confocal live imaging of early embryos we quantified cell size asymmetries in 16-cell stage embryos of two sea star species, Patiria miniata and Patiriella regularis. Using photoconversion to perform lineage tracing, we find that the position of the smallest cells of P. miniata embryos is biased toward anterior ventral tissues. However, both blastomere dissociation and mechanical removal of one small cell do not prevent dorsoventral (DV) axis formation, suggesting that embryos compensate for the loss of those cells and that asymmetrical partitioning of maternal determinants is not strictly necessary for DV patterning. Finally, we show that manipulating cell size to introduce artificial cell size asymmetries is not sufficient to direct the positioning of the future DV axis in P. miniata embryos. Conclusions Our results show that although cell size asymmetries are consistently produced during sea star early cleavage and are predictive of the DV axis, they are not necessary to instruct DV axis formation. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01359-3.
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Ettensohn CA. Embryonic polarity: Focusing on Dishevelled. Curr Biol 2021; 31:R1582-R1585. [PMID: 34932969 DOI: 10.1016/j.cub.2021.10.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The early polarity of animal embryos is typically established by molecules that are asymmetrically localized in the oocyte. A new study reveals that the Wnt signaling effector Dishevelled, an evolutionarily conserved, maternal regulator of embryonic polarity, is dynamically redistributed during oogenesis in a process regulated by the cell cycle and by the Wnt receptor Frizzled 1.
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Affiliation(s)
- Charles A Ettensohn
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
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Wijesena N, Sun H, Kumburegama S, Wikramanayake AH. Distinct Frizzled receptors independently mediate endomesoderm specification and primary archenteron invagination during gastrulation in Nematostella. Dev Biol 2021; 481:215-225. [PMID: 34767794 DOI: 10.1016/j.ydbio.2021.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 11/03/2021] [Accepted: 11/05/2021] [Indexed: 11/03/2022]
Abstract
Endomesodermal cell fate specification and archenteron formation during gastrulation are tightly linked developmental processes in most metazoans. However, studies have shown that in the anthozoan cnidarian Nematostella vectensis, Wnt/β-catenin (cWnt) signalling-mediated endomesodermal cell fate specification can be experimentally uncoupled from Wnt/Planar Cell Polarity (PCP) signalling-mediated primary archenteron invagination. The upstream signalling mechanisms regulating cWnt signalling-dependent endomesoderm cell fate specification and Wnt/PCP signalling-mediated primary archenteron invagination in Nematostella embryos are not well understood. By screening for potential upstream mediators of cWnt and Wnt/PCP signalling, we identified two Nematostella Frizzled homologs that are expressed early in development. NvFzd1 is expressed maternally and in a broad pattern during early development while NvFzd10 is zygotically expressed at the animal pole in blastula stage embryos and is restricted to the invaginating cells of the presumptive endomesoderm. Molecular and morphological characterization of NvFzd1 and NvFzd10 knock-down phenotypes provide evidence for distinct regulatory roles for the two receptors in endomesoderm cell fate specification and primary archenteron invagination. These results provide further experimental evidence for the independent regulation of endomesodermal cell fate specification and primary archenteron invagination during gastrulation in Nematostella. Moreover, these results provide additional support for the previously proposed two-step model for the independent evolution of cWnt-mediated cell fate specification and Wnt/PCP-mediated primary archenteron invagination.
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Affiliation(s)
- Naveen Wijesena
- Department of Biology, University of Miami, Coral Gables, FL33146, USA; Department of Biology, University of Bergen, Bergen, Norway
| | - Hongyan Sun
- Department of Biology, University of Miami, Coral Gables, FL33146, USA
| | - Shalika Kumburegama
- Department of Biology, University of Miami, Coral Gables, FL33146, USA; Department of Zoology, University of Peradeniya, Peradeniya, Sri Lanka
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