1
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Christodoulou N, Skourides PA. Distinct spatiotemporal contribution of morphogenetic events and mechanical tissue coupling during Xenopus neural tube closure. Development 2022; 149:275604. [PMID: 35662330 PMCID: PMC9340557 DOI: 10.1242/dev.200358] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 05/25/2022] [Indexed: 11/29/2022]
Abstract
Neural tube closure (NTC) is a fundamental process during vertebrate development and is indispensable for the formation of the central nervous system. Here, using Xenopus laevis embryos, live imaging, single-cell tracking, optogenetics and loss-of-function experiments, we examine the roles of convergent extension and apical constriction, and define the role of the surface ectoderm during NTC. We show that NTC is a two-stage process with distinct spatiotemporal contributions of convergent extension and apical constriction at each stage. Convergent extension takes place during the first stage and is spatially restricted at the posterior tissue, whereas apical constriction occurs during the second stage throughout the neural plate. We also show that the surface ectoderm is mechanically coupled with the neural plate and its movement during NTC is driven by neural plate morphogenesis. Finally, we show that an increase in surface ectoderm resistive forces is detrimental for neural plate morphogenesis. Summary: Detailed characterization of the contribution of distinct morphogenetic processes and mechanical tissue coupling during neural tube closure, a process indispensable for central nervous system formation in vertebrates.
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Affiliation(s)
- Neophytos Christodoulou
- University of Cyprus Department of Biological Sciences , , P.O. Box 20537, 2109 Nicosia , Cyprus
| | - Paris A. Skourides
- University of Cyprus Department of Biological Sciences , , P.O. Box 20537, 2109 Nicosia , Cyprus
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2
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Gomes de Almeida P, Rifes P, Martins-Jesus AP, Pinheiro GG, Andrade RP, Thorsteinsdóttir S. Cell–Fibronectin Interactions and Actomyosin Contractility Regulate the Segmentation Clock and Spatio-Temporal Somite Cleft Formation during Chick Embryo Somitogenesis. Cells 2022; 11:cells11132003. [PMID: 35805087 PMCID: PMC9266262 DOI: 10.3390/cells11132003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 06/15/2022] [Accepted: 06/21/2022] [Indexed: 12/19/2022] Open
Abstract
Fibronectin is essential for somite formation in the vertebrate embryo. Fibronectin matrix assembly starts as cells emerge from the primitive streak and ingress in the unsegmented presomitic mesoderm (PSM). PSM cells undergo cyclic waves of segmentation clock gene expression, followed by Notch-dependent upregulation of meso1 in the rostral PSM which induces somite cleft formation. However, the relevance of the fibronectin matrix for these molecular processes remains unknown. Here, we assessed the role of the PSM fibronectin matrix in the spatio-temporal regulation of chick embryo somitogenesis by perturbing (1) extracellular fibronectin matrix assembly, (2) integrin–fibronectin binding, (3) Rho-associated protein kinase (ROCK) activity and (4) non-muscle myosin II (NM II) function. We found that integrin–fibronectin engagement and NM II activity are required for cell polarization in the nascent somite. All treatments resulted in defective somitic clefts and significantly perturbed meso1 and segmentation clock gene expression in the PSM. Importantly, inhibition of actomyosin-mediated contractility increased the period of hairy1/hes4 oscillations from 90 to 120 min. Together, our work strongly suggests that the fibronectin–integrin–ROCK–NM II axis regulates segmentation clock dynamics and dictates the spatio-temporal localization of somitic clefts.
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Affiliation(s)
- Patrícia Gomes de Almeida
- cE3c—CHANGE, Departmento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, 1740-016 Lisboa, Portugal; (P.G.d.A.); (P.R.); (G.G.P.)
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal; (A.P.M.-J.); (R.P.A.)
- Faculdade de Medicina e Ciências Biomédicas (FMCB), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Pedro Rifes
- cE3c—CHANGE, Departmento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, 1740-016 Lisboa, Portugal; (P.G.d.A.); (P.R.); (G.G.P.)
| | - Ana P. Martins-Jesus
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal; (A.P.M.-J.); (R.P.A.)
- Faculdade de Medicina e Ciências Biomédicas (FMCB), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Gonçalo G. Pinheiro
- cE3c—CHANGE, Departmento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, 1740-016 Lisboa, Portugal; (P.G.d.A.); (P.R.); (G.G.P.)
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal; (A.P.M.-J.); (R.P.A.)
- Faculdade de Medicina e Ciências Biomédicas (FMCB), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Raquel P. Andrade
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal; (A.P.M.-J.); (R.P.A.)
- Faculdade de Medicina e Ciências Biomédicas (FMCB), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
- Champalimaud Research Program, Champalimaud Center for the Unknown, 1400-038 Lisboa, Portugal
| | - Sólveig Thorsteinsdóttir
- cE3c—CHANGE, Departmento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, 1740-016 Lisboa, Portugal; (P.G.d.A.); (P.R.); (G.G.P.)
- Correspondence:
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3
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Shook DR, Wen JWH, Rolo A, O'Hanlon M, Francica B, Dobbins D, Skoglund P, DeSimone DW, Winklbauer R, Keller RE. Characterization of convergent thickening, a major convergence force producing morphogenic movement in amphibians. eLife 2022; 11:e57642. [PMID: 35404236 PMCID: PMC9064293 DOI: 10.7554/elife.57642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 04/10/2022] [Indexed: 01/09/2023] Open
Abstract
The morphogenic process of convergent thickening (CT) was originally described as the mediolateral convergence and radial thickening of the explanted ventral involuting marginal zone (IMZ) of Xenopus gastrulae (Keller and Danilchik, 1988). Here, we show that CT is expressed in all sectors of the pre-involution IMZ, which transitions to expressing convergent extension (CE) after involution. CT occurs without CE and drives symmetric blastopore closure in ventralized embryos. Assays of tissue affinity and tissue surface tension measurements suggest CT is driven by increased interfacial tension between the deep IMZ and the overlying epithelium. The resulting minimization of deep IMZ surface area drives a tendency to shorten the mediolateral (circumblastoporal) aspect of the IMZ, thereby generating tensile force contributing to blastopore closure (Shook et al., 2018). These results establish CT as an independent force-generating process of evolutionary significance and provide the first clear example of an oriented, tensile force generated by an isotropic, Holtfreterian/Steinbergian tissue affinity change.
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Affiliation(s)
- David R Shook
- Department of Biology, University of VirginiaCharlottesvilleUnited States
- Department of Cell Biology, University of Virginia, School of MedicineCharlottesvilleUnited States
| | - Jason WH Wen
- Department of Cell and Systems Biology, University of TorontoTorontoCanada
| | - Ana Rolo
- Centre for Craniofacial and Regenerative Biology, King's College LondonLondonUnited Kingdom
| | - Michael O'Hanlon
- Department of Cell Biology, University of Virginia, School of MedicineCharlottesvilleUnited States
| | | | | | - Paul Skoglund
- Department of Biology, University of VirginiaCharlottesvilleUnited States
| | - Douglas W DeSimone
- Department of Cell Biology, University of Virginia, School of MedicineCharlottesvilleUnited States
| | - Rudolf Winklbauer
- Department of Cell and Systems Biology, University of TorontoTorontoCanada
| | - Ray E Keller
- Department of Biology, University of VirginiaCharlottesvilleUnited States
- Department of Cell Biology, University of Virginia, School of MedicineCharlottesvilleUnited States
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4
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Vermeulen S, Birgani ZT, Habibovic P. Biomaterial-induced pathway modulation for bone regeneration. Biomaterials 2022; 283:121431. [DOI: 10.1016/j.biomaterials.2022.121431] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/28/2022] [Accepted: 02/17/2022] [Indexed: 12/18/2022]
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5
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Weinberg SH, Saini N, Lemmon CA. Effects of substrate stiffness and actin velocity on in silico fibronectin fibril morphometry and mechanics. PLoS One 2021; 16:e0248256. [PMID: 34106923 PMCID: PMC8189481 DOI: 10.1371/journal.pone.0248256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 05/14/2021] [Indexed: 12/03/2022] Open
Abstract
Assembly of the extracellular matrix protein fibronectin (FN) into insoluble, viscoelastic fibrils is a critical step during embryonic development and wound healing; misregulation of FN fibril assembly has been implicated in many diseases, including fibrotic diseases and cancer. We have previously developed a computational model of FN fibril assembly that recapitulates the morphometry and mechanics of cell-derived FN fibrils. Here we use this model to probe two important questions: how is FN fibril formation affected by the contractile phenotype of the cell, and how is FN fibril formation affected by the stiffness of the surrounding tissue? We show that FN fibril formation depends strongly on the contractile phenotype of the cell, but only weakly on in vitro substrate stiffness, which is an analog for in vivo tissue stiffness. These results are consistent with previous experimental data and provide a better insight into conditions that promote FN fibril assembly. We have also investigated two distinct phenotypes of FN fibrils that we have previously identified; we show that the ratio of the two phenotypes depends on both substrate stiffness and contractile phenotype, with intermediate contractility and high substrate stiffness creating an optimal condition for stably stretched fibrils. Finally, we have investigated how re-stretch of a fibril affects cellular response. We probed how the contractile phenotype of the re-stretching cell affects the mechanics of the fibril; results indicate that the number of myosin motors only weakly affects the cellular response, but increasing actin velocity results in a decrease in the apparent stiffness of the fibril and a decrease in the stably-applied force to the fibril. Taken together, these results give novel insights into the combinatorial effects of substrate stiffness and cell contractility on FN fibril assembly.
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Affiliation(s)
- Seth H. Weinberg
- Department of Biomedical Engineering, Ohio State University, Columbus, OH, United States of America
- * E-mail: (CAL); (SHW)
| | - Navpreet Saini
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, United States of America
| | - Christopher A. Lemmon
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, United States of America
- * E-mail: (CAL); (SHW)
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6
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Weir E, McLinden G, Alfandari D, Cousin H. Trim-Away mediated knock down uncovers a new function for Lbh during gastrulation of Xenopus laevis. Dev Biol 2020; 470:74-83. [PMID: 33159936 DOI: 10.1016/j.ydbio.2020.10.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 08/28/2020] [Accepted: 10/29/2020] [Indexed: 10/23/2022]
Abstract
We previously identified the protein Lbh as necessary for cranial neural crest (CNC) cell migration in Xenopus through the use of morpholinos. However, Lbh is a maternally deposited protein and morpholinos achieve knockdowns through prevention of translation. In order to investigate the role of Lbh in earlier embryonic events, we employed the new technique "Trim-Away" to degrade this maternally deposited protein. Trim-Away utilizes the E3 ubiquitin ligase trim21 to degrade proteins targeted with an antibody and was developed in mammalian systems. Our results show that Xenopus is amenable to the Trim-Away technique. We also show that early knockdown of Lbh in Xenopus results in defects in gastrulation that present with a decrease in fibronectin matrix assembly, an increased in mesodermal cell migration and decrease in endodermal cell cohesion. We further show that the technique is also effective on a second abundant maternal protein PACSIN2. We discuss potential advantages and limit of the technique in Xenopus embryos as well as the mechanism of gastrulation inhibition.
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Affiliation(s)
- Emma Weir
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, USA
| | - Gretchen McLinden
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, USA
| | - Dominique Alfandari
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, USA
| | - Hélène Cousin
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, USA.
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7
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Collins C, Ventrella R, Mitchell BJ. Building a ciliated epithelium: Transcriptional regulation and radial intercalation of multiciliated cells. Curr Top Dev Biol 2020; 145:3-39. [PMID: 34074533 DOI: 10.1016/bs.ctdb.2020.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The epidermis of the Xenopus embryo has emerged as a powerful tool for studying the development of a ciliated epithelium. Interspersed throughout the epithelium are multiciliated cells (MCCs) with 100+ motile cilia that beat in a coordinated manner to generate fluid flow over the surface of the cell. MCCs are essential for various developmental processes and, furthermore, ciliary dysfunction is associated with numerous pathologies. Therefore, understanding the cellular mechanisms involved in establishing a ciliated epithelium are of particular interest. MCCs originate in the inner epithelial layer of Xenopus skin, where Notch signaling plays a critical role in determining which progenitors will adopt a ciliated cell fate. Then, activation of various transcriptional regulators, such as GemC1 and MCIDAS, initiate the MCC transcriptional program, resulting in centriole amplification and the formation of motile cilia. Following specification and differentiation, MCCs undergo the process of radial intercalation, where cells apically migrate from the inner layer to the outer epithelial layer. This process involves the cooperation of various cytoskeletal networks, activation of various signaling molecules, and changes in cell-ECM and cell-cell adhesion. Coordination of these cellular processes is required for complete incorporation into the outer epithelial layer and generation of a functional ciliated epithelium. Here, we highlight recent advances made in understanding the transcriptional cascades required for MCC specification and differentiation and the coordination of cellular processes that facilitate radial intercalation. Proper regulation of these signaling pathways and processes are the foundation for developing a ciliated epithelium.
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Affiliation(s)
- Caitlin Collins
- Department of Cell and Developmental Biology, Lurie Comprehensive Cancer Center, Northwestern University, Feinberg School of Medicine, Chicago, IL, United States
| | - Rosa Ventrella
- Department of Cell and Developmental Biology, Lurie Comprehensive Cancer Center, Northwestern University, Feinberg School of Medicine, Chicago, IL, United States
| | - Brian J Mitchell
- Department of Cell and Developmental Biology, Lurie Comprehensive Cancer Center, Northwestern University, Feinberg School of Medicine, Chicago, IL, United States.
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8
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Khadilkar RJ, Ho KYL, Venkatesh B, Tanentzapf G. Integrins Modulate Extracellular Matrix Organization to Control Cell Signaling during Hematopoiesis. Curr Biol 2020; 30:3316-3329.e5. [PMID: 32649911 DOI: 10.1016/j.cub.2020.06.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 05/04/2020] [Accepted: 06/08/2020] [Indexed: 11/25/2022]
Abstract
During hematopoiesis, progenitor cells receive and interpret a diverse array of regulatory signals from their environment. These signals control the maintenance of the progenitors and regulate the production of mature blood cells. Integrins are well known in vertebrates for their roles in hematopoiesis, particularly in assisting in the migration to, as well as the physical attachment of, progenitors to the niche. However, whether and how integrins are also involved in the signaling mechanisms that control hematopoiesis remains to be resolved. Here, we show that integrins play a key role during fly hematopoiesis in regulating cell signals that control the behavior of hematopoietic progenitors. Integrins can regulate hematopoiesis directly, via focal adhesion kinase (FAK) signaling, and indirectly, by directing extracellular matrix (ECM) assembly and/or maintenance. ECM organization and density controls blood progenitor behavior by modulating multiple signaling pathways, including bone morphogenetic protein (BMP) and Hedgehog (Hh). Furthermore, we show that integrins and the ECM are reduced following infection, which may assist in activating the immune response. Our results provide mechanistic insight into how integrins can shape the signaling environment around hematopoietic progenitors.
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Affiliation(s)
- Rohan J Khadilkar
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Kevin Y L Ho
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Bhavya Venkatesh
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Guy Tanentzapf
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
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9
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Anastasiou O, Hadjisavva R, Skourides PA. Mitotic cell responses to substrate topological cues are independent of the molecular nature of adhesion. Sci Signal 2020; 13:13/620/eaax9940. [PMID: 32098802 DOI: 10.1126/scisignal.aax9940] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Correct selection of the cell division axis is important for cell differentiation, tissue and organ morphogenesis, and homeostasis. Both integrins, which mediate interactions with extracellular matrix (ECM) components such as fibronectin, and cadherins, which mediate interactions between cells, are implicated in the determination of spindle orientation. We found that both cadherin- and integrin-based adhesion resulted in cell divisions parallel to the attachment plane and elicited identical spindle responses to spatial adhesive cues. This suggests that adhesion topology provides purely mechanical spatial cues that are independent of the molecular nature of the interaction or signaling from adhesion complexes. We also demonstrated that cortical integrin activation was indispensable for correct spindle orientation on both cadherin and fibronectin substrates. These data suggest that spindle orientation responses to adhesion topology are primarily a result of force anisotropy on the cell cortex and show that integrins play a central role in this process that is distinct from their role in cell-ECM interactions.
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Affiliation(s)
- Ouranio Anastasiou
- Department of Biological Sciences, University of Cyprus, University Avenue 1, New Campus, Nicosia 2109, Cyprus
| | - Rania Hadjisavva
- Department of Biological Sciences, University of Cyprus, University Avenue 1, New Campus, Nicosia 2109, Cyprus
| | - Paris A Skourides
- Department of Biological Sciences, University of Cyprus, University Avenue 1, New Campus, Nicosia 2109, Cyprus.
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10
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Abstract
This review is a comprehensive analysis of the cell biology and biomechanics of Convergent Extension in Xenopus.
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Affiliation(s)
- Ray Keller
- Department of Biology, University of Virginia, Charlottesville, VA, United States.
| | - Ann Sutherland
- Department of Biology, University of Virginia, Charlottesville, VA, United States
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11
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Cheng XN, Shao M, Shi DL. Collagen triple helix repeat containing 1a (Cthrc1a) regulates cell adhesion and migration during gastrulation in zebrafish. Exp Cell Res 2019; 381:112-120. [DOI: 10.1016/j.yexcr.2019.04.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 04/08/2019] [Accepted: 04/29/2019] [Indexed: 01/27/2023]
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12
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Abstract
Extracellular matrices (ECMs) are structurally and compositionally diverse networks of collagenous and noncollagenous glycoproteins, glycosaminoglycans, proteoglycans, and associated molecules that together comprise the metazoan matrisome. Proper deposition and assembly of ECM is of profound importance to cell proliferation, survival, and differentiation, and the morphogenesis of tissues and organ systems that define sequential steps in the development of all animals. Importantly, it is now clear that the instructive influence of a particular ECM at various points in development reflects more than a simple summing of component parts; cellular responses also reflect the dynamic assembly and changing topology of embryonic ECM, which in turn affect its biomechanical properties. This review highlights recent advances in understanding how biophysical features attributed to ECM, such as stiffness and viscoelasticity, play important roles in the sculpting of embryonic tissues and the regulation of cell fates. Forces generated within cells and tissues are transmitted both through integrin-based adhesions to ECM, and through cadherin-dependent cell-cell adhesions; the resulting short- and long-range deformations of embryonic tissues drive morphogenesis. This coordinate regulation of cell-ECM and cell-cell adhesive machinery has emerged as a common theme in a variety of developmental processes. In this review we consider select examples in the embryo where ECM is implicated in setting up tissue barriers and boundaries, in resisting pushing or pulling forces, or in constraining or promoting cell and tissue movement. We reflect on how each of these processes contribute to morphogenesis.
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13
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Hashimoto Y, Kinoshita N, Greco TM, Federspiel JD, Jean Beltran PM, Ueno N, Cristea IM. Mechanical Force Induces Phosphorylation-Mediated Signaling that Underlies Tissue Response and Robustness in Xenopus Embryos. Cell Syst 2019; 8:226-241.e7. [PMID: 30852251 DOI: 10.1016/j.cels.2019.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 12/17/2018] [Accepted: 01/28/2019] [Indexed: 12/21/2022]
Abstract
Mechanical forces are essential drivers of numerous biological processes, notably during development. Although it is well recognized that cells sense and adapt to mechanical forces, the signal transduction pathways that underlie mechanosensing have remained elusive. Here, we investigate the impact of mechanical centrifugation force on phosphorylation-mediated signaling in Xenopus embryos. By monitoring temporal phosphoproteome and proteome alterations in response to force, we discover and validate elevated phosphorylation on focal adhesion and tight junction components, leading to several mechanistic insights into mechanosensing and tissue restoration. First, we determine changes in kinase activity profiles during mechanoresponse, identifying the activation of basophilic kinases. Pathway interrogation using kinase inhibitor treatment uncovers a crosstalk between the focal adhesion kinase (FAK) and protein kinase C (PKC) in mechanoresponse. Second, we find LIM domain 7 protein (Lmo7) as upregulated upon centrifugation, contributing to mechanoresponse. Third, we discover that mechanical compression force induces a mesenchymal-to-epithelial transition (MET)-like phenotype.
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Affiliation(s)
- Yutaka Hashimoto
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA; Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan
| | - Noriyuki Kinoshita
- Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan
| | - Todd M Greco
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA
| | - Joel D Federspiel
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA
| | - Pierre M Jean Beltran
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA
| | - Naoto Ueno
- Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan.
| | - Ileana M Cristea
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA.
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14
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Hu B, Gao Y, Davies L, Woo S, Topczewski J, Jessen JR, Lin F. Glypican 4 and Mmp14 interact in regulating the migration of anterior endodermal cells by limiting extracellular matrix deposition. Development 2018; 145:dev.163303. [PMID: 30082271 DOI: 10.1242/dev.163303] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 07/16/2018] [Indexed: 01/30/2023]
Abstract
During embryogenesis, the germ layers, including the endoderm, undergo convergence and extension movements to narrow and elongate the body plan. In zebrafish, the dorsal migration of endodermal cells during gastrulation is controlled by chemokine signaling, but little is known about how they migrate during segmentation. Here, we show that glypican 4 (Gpc4), a member of the heparin sulfate proteoglycan family, is required for efficient migration of anterior endodermal cells during early segmentation, regulating Rac activation to maintain polarized actin-rich lamellipodia. An endoderm transplantation assay showed that Gpc4 regulates endoderm migration in a non-cell-autonomous fashion. Further analyses revealed that the impaired endoderm migration in gpc4 mutants results from increases in the expression and assembly of fibronectin and laminin, major components of the extracellular matrix (ECM). Notably, we found that matrix metalloproteinase 14 (Mmp14a/b) is required for the control of ECM expression during endoderm migration, with Gpc4 acting through Mmp14a/b to limit ECM expression. Our results suggest that Gpc4 is crucial for generating the environment required for efficient migration of endodermal cells, uncovering a novel function of Gpc4 during development.
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Affiliation(s)
- Bo Hu
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Yuanyuan Gao
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Lauren Davies
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Stephanie Woo
- School of Natural Sciences, Merced, University of California Merced, Merced, CA 95340, USA
| | - Jacek Topczewski
- Northwestern University, Feinberg School of Medicine, Stanley Manne Children's Research Institute, Chicago, IL 60611, USA.,Department of Biochemistry and Molecular Biology, Medical University of Lublin, Lublin 20-093, Poland
| | - Jason R Jessen
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN 37132, USA
| | - Fang Lin
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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15
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Huang Y, Winklbauer R. Cell migration in the Xenopus gastrula. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2018; 7:e325. [PMID: 29944210 DOI: 10.1002/wdev.325] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 05/22/2018] [Accepted: 05/30/2018] [Indexed: 12/17/2022]
Abstract
Xenopus gastrulation movements are in large part based on the rearrangement of cells by differential cell-on-cell migration within multilayered tissues. Different patterns of migration-based cell intercalation drive endoderm and mesoderm internalization and their positioning along their prospective body axes. C-cadherin, fibronectin, integrins, and focal contact components are expressed in all gastrula cells and play putative roles in cell-on-cell migration, but their actual functions in this respect are not yet understood. The gastrula can be subdivided into two motility domains, and in the vegetal, migratory domain, two modes of cell migration are discerned. Vegetal endoderm cells show ingression-type migration, a variant of amoeboid migration characterized by the lack of locomotory protrusions and by macropinocytosis as a mechanism of trailing edge resorption. Mesendoderm and prechordal mesoderm cells use lamellipodia in a mesenchymal mode of migration. Gastrula cell motility can be dissected into traits, such as cell polarity, adhesion, mobility, or protrusive activity, which are controlled separately yet in complex, combinatorial ways. Cells can instantaneously switch between different combinations of traits, showing plasticity as they respond to substratum properties. This article is categorized under: Early Embryonic Development > Gastrulation and Neurulation.
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Affiliation(s)
- Yunyun Huang
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Rudolf Winklbauer
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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16
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Shook DR, Kasprowicz EM, Davidson LA, Keller R. Large, long range tensile forces drive convergence during Xenopus blastopore closure and body axis elongation. eLife 2018; 7:e26944. [PMID: 29533180 PMCID: PMC5896886 DOI: 10.7554/elife.26944] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 03/12/2018] [Indexed: 02/03/2023] Open
Abstract
Indirect evidence suggests that blastopore closure during gastrulation of anamniotes, including amphibians such as Xenopus laevis, depends on circumblastoporal convergence forces generated by the marginal zone (MZ), but direct evidence is lacking. We show that explanted MZs generate tensile convergence forces up to 1.5 μN during gastrulation and over 4 μN thereafter. These forces are generated by convergent thickening (CT) until the midgastrula and increasingly by convergent extension (CE) thereafter. Explants from ventralized embryos, which lack tissues expressing CE but close their blastopores, produce up to 2 μN of tensile force, showing that CT alone generates forces sufficient to close the blastopore. Uniaxial tensile stress relaxation assays show stiffening of mesodermal and ectodermal tissues around the onset of neurulation, potentially enhancing long-range transmission of convergence forces. These results illuminate the mechanobiology of early vertebrate morphogenic mechanisms, aid interpretation of phenotypes, and give insight into the evolution of blastopore closure mechanisms.
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Affiliation(s)
- David R Shook
- Department of BiologyUniversity of VirginiaCharlottesvilleUnited States
| | - Eric M Kasprowicz
- Department of Internal MedicineThomas Jefferson University HospitalPhiladelphiaUnited States
| | - Lance A Davidson
- Department of Computational and Systems BiologyUniversity of PittsburghPittsburghUnited States
- Department of BioengineeringUniversity of PittsburghPittsburghUnited States
| | - Raymond Keller
- Department of BiologyUniversity of VirginiaCharlottesvilleUnited States
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17
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Forecki J, Van Antwerp DJ, Lujan SM, Merzdorf CS. Roles for Xenopus aquaporin-3b (aqp3.L) during gastrulation: Fibrillar fibronectin and tissue boundary establishment in the dorsal margin. Dev Biol 2018; 433:3-16. [PMID: 29113748 DOI: 10.1016/j.ydbio.2017.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 11/02/2017] [Accepted: 11/02/2017] [Indexed: 01/02/2023]
Abstract
Aquaporins and aquaglyceroporins are a large family of membrane channel proteins that allow rapid movement of water and small, uncharged solutes into and out of cells along concentration gradients. Recently, aquaporins have been gaining recognition for more complex biological roles than the regulation of cellular osmotic homeostasis. We have identified a specific expression pattern for Xenopus aqp3b (also called aqp3.L) during gastrulation, where it is localized to the sensorial (deep) layer of the blastocoel roof and dorsal margin. Interference with aqp3b expression resulted in loss of fibrillar fibronectin matrix in Brachet's cleft at the dorsal marginal zone, but not on the free surface of the blastocoel. Detailed observation showed that the absence of fibronectin matrix correlated with compromised border integrities between involuted mesendoderm and noninvoluted ectoderm in the marginal zone. Knockdown of aqp3b also led to delayed closure of the blastopore, suggesting defects in gastrulation movements. Radial intercalation was not affected in aqp3b morphants, while the data presented are consistent with impeded convergent extension movements of the dorsal mesoderm in response to loss of aqp3b. Our emerging model suggests that aqp3b is part of a mechanism that promotes proper interaction between cells and the extracellular matrix, thereby playing a critical role in gastrulation.
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Affiliation(s)
- Jennifer Forecki
- Department of Cell Biology and Neuroscience, Montana State University, Bozeman, MT 59717, USA.
| | - Daniel J Van Antwerp
- Department of Cell Biology and Neuroscience, Montana State University, Bozeman, MT 59717, USA.
| | - Sean M Lujan
- Department of Cell Biology and Neuroscience, Montana State University, Bozeman, MT 59717, USA.
| | - Christa S Merzdorf
- Department of Cell Biology and Neuroscience, Montana State University, Bozeman, MT 59717, USA.
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18
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Shindo A. Models of convergent extension during morphogenesis. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2017; 7. [PMID: 28906063 PMCID: PMC5763355 DOI: 10.1002/wdev.293] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 07/23/2017] [Accepted: 08/06/2017] [Indexed: 11/29/2022]
Abstract
Convergent extension (CE) is a fundamental and conserved collective cell movement that forms elongated tissues during embryonic development. Thus far, studies have demonstrated two different mechanistic models of collective cell movements during CE. The first, termed the crawling mode, was discovered in the process of notochord formation in Xenopus laevis embryos, and has been the established model of CE for decades. The second model, known as the contraction mode, was originally reported in studies of germband extension in Drosophila melanogaster embryos and was recently demonstrated to be a conserved mechanism of CE among tissues and stages of development across species. This review summarizes the two modes of CE by focusing on the differences in cytoskeletal behaviors and relative expression of cell adhesion molecules. The upstream molecules regulating these machineries are also discussed. There are abundant studies of notochord formation in X. laevis embryos, as this was one of the pioneering model systems in this field. Therefore, the present review discusses these findings as an approach to the fundamental biological question of collective cell regulation. WIREs Dev Biol 2018, 7:e293. doi: 10.1002/wdev.293 This article is categorized under:
Early Embryonic Development > Gastrulation and Neurulation Comparative Development and Evolution > Model Systems
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Affiliation(s)
- Asako Shindo
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho Chikusa-ku, Nagoya, Japan
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19
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hmmr mediates anterior neural tube closure and morphogenesis in the frog Xenopus. Dev Biol 2017; 430:188-201. [PMID: 28778799 DOI: 10.1016/j.ydbio.2017.07.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 07/19/2017] [Accepted: 07/26/2017] [Indexed: 12/20/2022]
Abstract
Development of the central nervous system requires orchestration of morphogenetic processes which drive elevation and apposition of the neural folds and their fusion into a neural tube. The newly formed tube gives rise to the brain in anterior regions and continues to develop into the spinal cord posteriorly. Conspicuous differences between the anterior and posterior neural tube become visible already during neural tube closure (NTC). Planar cell polarity (PCP)-mediated convergent extension (CE) movements are restricted to the posterior neural plate, i.e. hindbrain and spinal cord, where they propagate neural fold apposition. The lack of CE in the anterior neural plate correlates with a much slower mode of neural fold apposition anteriorly. The morphogenetic processes driving anterior NTC have not been addressed in detail. Here, we report a novel role for the breast cancer susceptibility gene and microtubule (MT) binding protein Hmmr (Hyaluronan-mediated motility receptor, RHAMM) in anterior neurulation and forebrain development in Xenopus laevis. Loss of hmmr function resulted in a lack of telencephalic hemisphere separation, arising from defective roof plate formation, which in turn was caused by impaired neural tissue narrowing. hmmr regulated polarization of neural cells, a function which was dependent on the MT binding domains. hmmr cooperated with the core PCP component vangl2 in regulating cell polarity and neural morphogenesis. Disrupted cell polarization and elongation in hmmr and vangl2 morphants prevented radial intercalation (RI), a cell behavior essential for neural morphogenesis. Our results pinpoint a novel role of hmmr in anterior neural development and support the notion that RI is a major driving force for anterior neurulation and forebrain morphogenesis.
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20
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Pickett MA, Dush MK, Nascone-Yoder NM. Acetylcholinesterase plays a non-neuronal, non-esterase role in organogenesis. Development 2017; 144:2764-2770. [PMID: 28684626 DOI: 10.1242/dev.149831] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 06/19/2017] [Indexed: 01/10/2023]
Abstract
Acetylcholinesterase (AChE) is crucial for degrading acetylcholine at cholinergic synapses. In vitro studies suggest that, in addition to its role in nervous system signaling, AChE can also modulate non-neuronal cell properties, although it remains controversial whether AChE functions in this capacity in vivo Here, we show that AChE plays an essential non-classical role in vertebrate gut morphogenesis. Exposure of Xenopus embryos to AChE-inhibiting chemicals results in severe defects in intestinal development. Tissue-targeted loss-of-function assays (via microinjection of antisense morpholino or CRISPR-Cas9) confirm that AChE is specifically required in the gut endoderm tissue, a non-neuronal cell population, where it mediates adhesion to fibronectin and regulates cell rearrangement events that drive gut lengthening and digestive epithelial morphogenesis. Notably, the classical esterase activity of AChE is dispensable for this activity. As AChE is deeply conserved, widely expressed outside of the nervous system, and the target of many environmental chemicals, these results have wide-reaching implications for development and toxicology.
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Affiliation(s)
- Melissa A Pickett
- Department of Biology, Environmental and Molecular Toxicology Program, North Carolina State University, Raleigh, NC 27606, USA
| | - Michael K Dush
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
| | - Nanette M Nascone-Yoder
- Department of Biology, Environmental and Molecular Toxicology Program, North Carolina State University, Raleigh, NC 27606, USA .,Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
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21
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The Molecular Basis of Radial Intercalation during Tissue Spreading in Early Development. Dev Cell 2017; 37:213-25. [PMID: 27165554 PMCID: PMC4865533 DOI: 10.1016/j.devcel.2016.04.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 03/18/2016] [Accepted: 04/08/2016] [Indexed: 02/08/2023]
Abstract
Radial intercalation is a fundamental process responsible for the thinning of multilayered tissues during large-scale morphogenesis; however, its molecular mechanism has remained elusive. Using amphibian epiboly, the thinning and spreading of the animal hemisphere during gastrulation, here we provide evidence that radial intercalation is driven by chemotaxis of cells toward the external layer of the tissue. This role of chemotaxis in tissue spreading and thinning is unlike its typical role associated with large-distance directional movement of cells. We identify the chemoattractant as the complement component C3a, a factor normally linked with the immune system. The mechanism is explored by computational modeling and tested in vivo, ex vivo, and in vitro. This mechanism is robust against fluctuations of chemoattractant levels and expression patterns and explains expansion during epiboly. This study provides insight into the fundamental process of radial intercalation and could be applied to a wide range of morphogenetic events.
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22
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Stooke-Vaughan GA, Davidson LA, Woolner S. Xenopus as a model for studies in mechanical stress and cell division. Genesis 2017; 55. [PMID: 28095623 DOI: 10.1002/dvg.23004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 11/17/2016] [Accepted: 11/17/2016] [Indexed: 01/03/2023]
Abstract
We exist in a physical world, and cells within biological tissues must respond appropriately to both environmental forces and forces generated within the tissue to ensure normal development and homeostasis. Cell division is required for normal tissue growth and maintenance, but both the direction and rate of cell division must be tightly controlled to avoid diseases of over-proliferation such as cancer. Recent studies have shown that mechanical cues can cause mitotic entry and orient the mitotic spindle, suggesting that physical force could play a role in patterning tissue growth. However, to fully understand how mechanics guides cells in vivo, it is necessary to assess the interaction of mechanical strain and cell division in a whole tissue context. In this mini-review we first summarise the body of work linking mechanics and cell division, before looking at the advantages that the Xenopus embryo can offer as a model organism for understanding: (1) the mechanical environment during embryogenesis, and (2) factors important for cell division. Finally, we introduce a novel method for applying a reproducible strain to Xenopus embryonic tissue and assessing subsequent cell divisions.
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Affiliation(s)
- Georgina A Stooke-Vaughan
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
| | - Lance A Davidson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, 15213.,Department of Developmental Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, 15213.,Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, 15213
| | - Sarah Woolner
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
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23
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Davis A, Amin NM, Johnson C, Bagley K, Ghashghaei HT, Nascone-Yoder N. Stomach curvature is generated by left-right asymmetric gut morphogenesis. Development 2017; 144:1477-1483. [PMID: 28242610 PMCID: PMC5399665 DOI: 10.1242/dev.143701] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 02/21/2017] [Indexed: 01/09/2023]
Abstract
Left-right (LR) asymmetry is a fundamental feature of internal anatomy, yet the emergence of morphological asymmetry remains one of the least understood phases of organogenesis. Asymmetric rotation of the intestine is directed by forces outside the gut, but the morphogenetic events that generate anatomical asymmetry in other regions of the digestive tract remain unknown. Here, we show in mouse and Xenopus that the mechanisms that drive the curvature of the stomach are intrinsic to the gut tube itself. The left wall of the primitive stomach expands more than the right wall, as the left epithelium becomes more polarized and undergoes radial rearrangement. These asymmetries exist across several species, and are dependent on LR patterning genes, including Foxj1, Nodal and Pitx2 Our findings have implications for how LR patterning manifests distinct types of morphological asymmetries in different contexts.
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Affiliation(s)
- Adam Davis
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
| | - Nirav M Amin
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
| | - Caroline Johnson
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
| | - Kristen Bagley
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
| | - H Troy Ghashghaei
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
| | - Nanette Nascone-Yoder
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
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24
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Zhu Z, Di J, Lu Z, Gao K, Zheng J. Rap2B GTPase: structure, functions, and regulation. Tumour Biol 2016; 37:7085-93. [PMID: 27012552 DOI: 10.1007/s13277-016-5033-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/18/2016] [Indexed: 02/08/2023] Open
Abstract
Rap2B GTPase, a member of Ras-related protein superfamily, was first discovered from a platelet cDNA library in the early 1990s. Since then, it has been reported to play an important role in regulating cellular processes including cytoskeletal organization, cell growth, and proliferation. It can be stimulated and suppressed by a wide range of external and internal inducers, circulating between GTP-bound active state and GDP-bound inactive state. Increasing focus on Ras signaling pathway reveals critical effects of Rap2B on tumorigenesis. In particular, Rap2B behaves in a p53-dependent manner in regulation of apoptosis and migration. Apart from being an oncogenic activator, Rap2B has been found to participate in many other physiological events via diverse downstream effectors. In this review, we present recent studies on the structure, regulation, and multiple biological functions of Rap2B, shedding light on its potential status in treatment of cancer as well as other diseases.
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Affiliation(s)
- Zhesi Zhu
- Cancer Institute, Xuzhou Medical College, Xuzhou, 221002, Jiangsu, People's Republic of China
| | - Jiehui Di
- Cancer Institute, Xuzhou Medical College, Xuzhou, 221002, Jiangsu, People's Republic of China.,Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, School of Medicine, The University of North Carolina at Chapel Hill, 101 Manning Drive, Chapel Hill, NC, 27514, USA
| | - Zheng Lu
- Cancer Institute, Xuzhou Medical College, Xuzhou, 221002, Jiangsu, People's Republic of China
| | - Keyu Gao
- Cancer Institute, Xuzhou Medical College, Xuzhou, 221002, Jiangsu, People's Republic of China
| | - Junnian Zheng
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical College, Xuzhou, 221002, Jiangsu, People's Republic of China. .,Center of Clinical Oncology, Affiliated Hospital of Xuzhou Medical College, Xuzhou, China.
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25
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Panousopoulou E, Hobbs C, Mason I, Green JBA, Formstone CJ. Epiboly generates the epidermal basal monolayer and spreads the nascent mammalian skin to enclose the embryonic body. J Cell Sci 2016; 129:1915-27. [PMID: 26989131 PMCID: PMC4893800 DOI: 10.1242/jcs.180703] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 03/14/2016] [Indexed: 01/09/2023] Open
Abstract
Epiboly is a morphogenetic process that is employed in the surface ectoderm of anamniotes during gastrulation to cover the entire embryo. We propose here that mammals also utilise this process to expand the epidermis and enclose the body cavity and spinal cord with a protective surface covering. Our data supports a model whereby epidermal spreading is driven by the primary establishment of the epidermal basal progenitor monolayer through radial cell intercalation of a multi-layered epithelium towards the basal lamina. By using a suspension organotypic culture strategy, we find that this process is fibronectin-dependent and autonomous to the skin. The radial cell rearrangements that drive epidermal spreading also require ROCK activity but are driven by cell protrusions and not myosin II contractility. Epidermal progenitor monolayer formation and epidermal spreading are delayed in Crash mice, which possess a dominant mutation in Celsr1, an orthologue of the core planar cell polarity (PCP) Drosophila protein Flamingo (also known as Stan). We observe a failure of ventral enclosure in Crash mutants suggesting that defective epidermal spreading might underlie some ventral wall birth defects. Summary: The nascent mammalian epidermis spreads to enclose the embryo trunk through a process akin to epiboly, which has important implications for human birth defects of the abdominal wall.
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Affiliation(s)
- Eleni Panousopoulou
- Department of Craniofacial Development and Stem Cell Biology, Guys Tower, Kings College London, London SE1 1UL, UK
| | - Carl Hobbs
- Wolfson-CARD, Kings College London, London SE1 1UL, UK
| | - Ivor Mason
- MRC Centre for Developmental Neurobiology, New Hunts House, Kings College London, London SE1 1UL, UK
| | - Jeremy B A Green
- Department of Craniofacial Development and Stem Cell Biology, Guys Tower, Kings College London, London SE1 1UL, UK
| | - Caroline J Formstone
- MRC Centre for Developmental Neurobiology, New Hunts House, Kings College London, London SE1 1UL, UK
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26
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A ligand-independent integrin β1 mechanosensory complex guides spindle orientation. Nat Commun 2016; 7:10899. [PMID: 26952307 PMCID: PMC4786777 DOI: 10.1038/ncomms10899] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 01/29/2016] [Indexed: 12/20/2022] Open
Abstract
Control of spindle orientation is a fundamental process for embryonic development, morphogenesis and tissue homeostasis, while defects are associated with tumorigenesis and other diseases. Force sensing is one of the mechanisms through which division orientation is determined. Here we show that integrin β1 plays a critical role in this process, becoming activated at the lateral regions of the cell cortex in a ligand-independent manner. This activation is force dependent and polar, correlating with the spindle capture sites. Inhibition of integrin β1 activation on the cortex and disruption of its asymmetric distribution leads to spindle misorientation, even when cell adhesion is β1 independent. Examining downstream targets reveals that a cortical mechanosensory complex forms on active β1, and regulates spindle orientation irrespective of cell context. We propose that ligand-independent integrin β1 activation is a conserved mechanism that allows cell responses to external stimuli.
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27
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de Almeida PG, Pinheiro GG, Nunes AM, Gonçalves AB, Thorsteinsdóttir S. Fibronectin assembly during early embryo development: A versatile communication system between cells and tissues. Dev Dyn 2016; 245:520-35. [PMID: 26845241 DOI: 10.1002/dvdy.24391] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 01/20/2016] [Accepted: 01/25/2016] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Fibronectin extracellular matrix is essential for embryogenesis. Its assembly is a cell-mediated process where secreted fibronectin dimers bind to integrin receptors on receiving cells, which actively assemble fibronectin into a fibrillar matrix. During development, paracrine communication between tissues is crucial for coordinating morphogenesis, typically being mediated by growth factors and their receptors. Recent reports of situations where fibronectin is produced by one tissue and assembled by another, with implications on tissue morphogenesis, suggest that fibronectin assembly may also be a paracrine communication event in certain contexts. RESULTS Here we addressed which tissues express fibronectin (Fn1) while also localizing assembled fibronectin matrix and determining the mRNA expression and/or protein distribution pattern of integrins α5 and αV, α chains of the major fibronectin assembly receptors, during early chick and mouse development. We found evidence supporting a paracrine system in fibronectin matrix assembly in several tissues, including immature mesenchymal tissues, components of central and peripheral nervous system and developing muscle. CONCLUSIONS Thus, similarly to growth factor signaling, fibronectin matrix assembly during early development can be both autocrine and paracrine. We therefore propose that it be considered a cell-cell communication event at the same level and significance as growth factor signaling during embryogenesis.
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Affiliation(s)
- Patrícia Gomes de Almeida
- Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Gonçalo G Pinheiro
- Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Andreia M Nunes
- Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - André B Gonçalves
- Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Sólveig Thorsteinsdóttir
- Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
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28
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Ossipova O, Chu CW, Fillatre J, Brott BK, Itoh K, Sokol SY. The involvement of PCP proteins in radial cell intercalations during Xenopus embryonic development. Dev Biol 2015; 408:316-27. [PMID: 26079437 PMCID: PMC4810801 DOI: 10.1016/j.ydbio.2015.06.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 06/10/2015] [Accepted: 06/11/2015] [Indexed: 11/19/2022]
Abstract
The planar cell polarity (PCP) pathway orients cells in diverse epithelial tissues in Drosophila and vertebrate embryos and has been implicated in many human congenital defects and diseases, such as ciliopathies, polycystic kidney disease and malignant cancers. During vertebrate gastrulation and neurulation, PCP signaling is required for convergent extension movements, which are primarily driven by mediolateral cell intercalations, whereas the role for PCP signaling in radial cell intercalations has been unclear. In this study, we examine the function of the core PCP proteins Vangl2, Prickle3 (Pk3) and Disheveled in the ectodermal cells, which undergo radial intercalations during Xenopus gastrulation and neurulation. In the epidermis, multiciliated cell (MCC) progenitors originate in the inner layer, but subsequently migrate to the embryo surface during neurulation. We find that the Vangl2/Pk protein complexes are enriched at the apical domain of intercalating MCCs and are essential for the MCC intercalatory behavior. Addressing the underlying mechanism, we identified KIF13B, as a motor protein that binds Disheveled. KIF13B is required for MCC intercalation and acts synergistically with Vangl2 and Disheveled, indicating that it may mediate microtubule-dependent trafficking of PCP proteins necessary for cell shape regulation. In the neural plate, the Vangl2/Pk complexes were also concentrated near the outermost surface of deep layer cells, suggesting a general role for PCP in radial intercalation. Consistent with this hypothesis, the ectodermal tissues deficient in Vangl2 or Disheveled functions contained more cell layers than normal tissues. We propose that PCP signaling is essential for both mediolateral and radial cell intercalations during vertebrate morphogenesis. These expanded roles underscore the significance of vertebrate PCP proteins as factors contributing to a number of diseases, including neural tube defects, tumor metastases, and various genetic syndromes characterized by abnormal migratory cell behaviors.
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Affiliation(s)
- Olga Ossipova
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Chih-Wen Chu
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Jonathan Fillatre
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Barbara K Brott
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Keiji Itoh
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Sergei Y Sokol
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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29
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Green YS, Kwon S, Christian JL. Expression pattern of bcar3, a downstream target of Gata2, and its binding partner, bcar1, during Xenopus development. Gene Expr Patterns 2015; 20:55-62. [PMID: 26631802 DOI: 10.1016/j.gep.2015.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/09/2015] [Accepted: 11/23/2015] [Indexed: 01/28/2023]
Abstract
Primitive hematopoiesis generates red blood cells that deliver oxygen to the developing embryo. Mesodermal cells commit to a primitive blood cell fate during gastrulation and, in order to do so the mesoderm must receive non-cell autonomous signals transmitted from other germ layers. In Xenopus, the transcription factor Gata2 functions in ectodermal cells to generate or transmit the non-cell autonomous signals. Here we have identified Breast Cancer Antiestrogen Resistance 3 (bcar3) as a gene that is induced in ectodermal cells downstream of Gata2. Bcar3 and its binding partner Bcar1 function to transduce integrin signaling, leading to changes in cellular morphology, motility and adhesion. We show that gata2, bcar3 and bcar1 are co-expressed in ventral ectoderm from early gastrula to early tailbud stages. At later stages of development, bcar3 and bcar1 are co-expressed in the spinal cord, notochord, fin mesenchyme and pronephros but each shows additional unique sites of expression. These co-expression and unique expression patterns suggest that Bcar3 and Bcar1 may function together but also independently during Xenopus development.
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Affiliation(s)
- Yangsook Song Green
- Department of Neurobiology and Anatomy, Division of Hematology and Hematologic Malignancies, University of Utah, School of Medicine, 20 North 1900 East, Salt Lake City, UT 94132, USA; Department of Internal Medicine, Division of Hematology and Hematologic Malignancies, University of Utah, School of Medicine, 20 North 1900 East, Salt Lake City, UT 94132, USA
| | - Sunjong Kwon
- Department of Cell, Developmental and Cancer Biology, Oregon Health and Science University, School of Medicine, 3181 S.W. Sam Jackson Park Rd., Portland, OR 97239-3098, USA
| | - Jan L Christian
- Department of Neurobiology and Anatomy, Division of Hematology and Hematologic Malignancies, University of Utah, School of Medicine, 20 North 1900 East, Salt Lake City, UT 94132, USA; Department of Internal Medicine, Division of Hematology and Hematologic Malignancies, University of Utah, School of Medicine, 20 North 1900 East, Salt Lake City, UT 94132, USA.
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30
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Gudzenko T, Franz CM. Studying early stages of fibronectin fibrillogenesis in living cells by atomic force microscopy. Mol Biol Cell 2015. [DOI: 10.1091/mbc.e14-05-1026] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Fibronectin (FN) is an extracellular matrix protein that can be assembled by cells into large fibrillar networks, but the dynamics of FN remodeling and the transition through intermediate fibrillar stages are incompletely understood. Here we used a combination of fluorescence microscopy and time-lapse atomic force microscopy (AFM) to visualize initial stages of FN fibrillogenesis in living fibroblasts at high resolution. Initial FN nanofibrils form within <5 min of cell–matrix contact and subsequently extend at a rate of 0.25 μm/min at sites of cell membrane retraction. FN nanofibrils display a complex linear array of globular features spaced at varying distances, indicating the coexistence of different conformational states within the fibril. In some cases, initial fibrils extended in discrete increments of ∼800 nm during a series of cyclical membrane retractions, indicating a stepwise fibrillar extension mechanism. In presence of Mn2+, a known activator of integrin adhesion to FN, fibrillogenesis was accelerated almost threefold to 0.68 μm/min and fibrillar dimensions were increased, underlining the importance of integrin activation for early FN fibrillogenesis. FN fibrillogenesis visualized by time-lapse AFM thus provides new structural and mechanistic insight into initial steps of cell-driven FN fibrillogenesis.
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Affiliation(s)
- Tetyana Gudzenko
- DFG–Center for Functional Nanostructures, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Clemens M. Franz
- DFG–Center for Functional Nanostructures, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
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31
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Corallo D, Trapani V, Bonaldo P. The notochord: structure and functions. Cell Mol Life Sci 2015; 72:2989-3008. [PMID: 25833128 PMCID: PMC11114051 DOI: 10.1007/s00018-015-1897-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 03/23/2015] [Accepted: 03/26/2015] [Indexed: 01/08/2023]
Abstract
The notochord is an embryonic midline structure common to all members of the phylum Chordata, providing both mechanical and signaling cues to the developing embryo. In vertebrates, the notochord arises from the dorsal organizer and it is critical for proper vertebrate development. This evolutionary conserved structure located at the developing midline defines the primitive axis of embryos and represents the structural element essential for locomotion. Besides its primary structural function, the notochord is also a source of developmental signals that patterns surrounding tissues. Among the signals secreted by the notochord, Hedgehog proteins play key roles during embryogenesis. The Hedgehog signaling pathway is a central regulator of embryonic development, controlling the patterning and proliferation of a wide variety of organs. In this review, we summarize the current knowledge on notochord structure and functions, with a particular emphasis on the key developmental events that take place in vertebrates. Moreover, we discuss some genetic studies highlighting the phenotypic consequences of impaired notochord development, which enabled to understand the molecular basis of different human congenital defects and diseases.
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Affiliation(s)
- Diana Corallo
- Department of Molecular Medicine, University of Padova, Viale G. Colombo 3, 35131 Padua, Italy
| | - Valeria Trapani
- Department of Molecular Medicine, University of Padova, Viale G. Colombo 3, 35131 Padua, Italy
| | - Paolo Bonaldo
- Department of Molecular Medicine, University of Padova, Viale G. Colombo 3, 35131 Padua, Italy
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32
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Maartens AP, Brown NH. Anchors and signals: the diverse roles of integrins in development. Curr Top Dev Biol 2015; 112:233-72. [PMID: 25733142 DOI: 10.1016/bs.ctdb.2014.11.020] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Integrins mediate cell adhesion by providing a link between the actin cytoskeleton and the extracellular matrix. As well as acting to anchor cells, integrin adhesions provide sensory input via mechanotransduction and synergism with signaling pathways, and provide the cell with the conditions necessary for differentiation in a permissive manner. In this review, we explore how integrins contribute to development, and what this tells us about how they work. From a signaling perspective, the influence of integrins on cell viability and fate is muted in a developmental context as compared to cell culture. Integrin phenotypes tend to arise from a failure of normally specified cells to create tissues properly, due to defective adhesion. The diversity of integrin functions in development shows how cell adhesion is continuously adjusted, both within and between animals, to fit developmental purpose.
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Affiliation(s)
- Aidan P Maartens
- Department of Physiology, Development and Neuroscience, The Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
| | - Nicholas H Brown
- Department of Physiology, Development and Neuroscience, The Gurdon Institute, University of Cambridge, Cambridge, United Kingdom.
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33
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Eagleson G, Pfister K, Knowlton AL, Skoglund P, Keller R, Stukenberg PT. Kif2a depletion generates chromosome segregation and pole coalescence defects in animal caps and inhibits gastrulation of the Xenopus embryo. Mol Biol Cell 2015; 26:924-37. [PMID: 25568341 PMCID: PMC4342028 DOI: 10.1091/mbc.e13-12-0721] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Characterization of Kif2a in Xenopus embryos identifies new roles for the Kif2a microtubule depolymerase in coordinating cytokinesis and centrosome coalescence. In addition, defects in mitosis can inhibit large-scale developmental movements in vertebrate tissues. Kif2a is a member of the kinesin-13 microtubule depolymerases, which tightly regulate microtubule dynamics for many cellular processes. We characterized Kif2a depletion in Xenopus animal caps and embryos. Kif2a depletion generates defects in blastopore closure. These defects are rescued by removing the animal cap, suggesting that Kif2a-depleted animal caps are not compliant enough to allow gastrulation movements. Gastrulation defects are not rescued by a Kif2a mutated in an Aurora kinase phosphorylation site, suggesting that the phenotypes are caused by problems in mitosis. During animal cap mitoses, Kif2a localizes to the spindle poles and centromeres. Depletion of Kif2a generated multipolar spindles in stage 12 embryos. Kif2a-depleted animal caps have anaphase lagging chromosomes in stage 9 and 10 embryos and subsequent cytokinesis failure. Later divisions have greater than two centrosomes, generating extra spindle poles. Kif2a-depleted embryos are also defective at coalescing extra spindle poles into a bipolar spindle. The gastrulation and mitotic phenotypes can be rescued by either human Kif2a or Kif2b, which suggests that the two homologues redundantly regulate mitosis in mammals. These studies demonstrate that defects in mitosis can inhibit large-scale developmental movements in vertebrate tissues.
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Affiliation(s)
- Gerald Eagleson
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Katherine Pfister
- Department of Biology, University of Virginia, Charlottesville, VA 22904
| | - Anne L Knowlton
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Paul Skoglund
- Department of Biology, University of Virginia, Charlottesville, VA 22904
| | - Ray Keller
- Department of Biology, University of Virginia, Charlottesville, VA 22904
| | - P Todd Stukenberg
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908
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34
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A novel RIPK4-IRF6 connection is required to prevent epithelial fusions characteristic for popliteal pterygium syndromes. Cell Death Differ 2014; 22:1012-24. [PMID: 25430793 DOI: 10.1038/cdd.2014.191] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 10/21/2014] [Accepted: 10/22/2014] [Indexed: 01/04/2023] Open
Abstract
Receptor-interacting protein kinase 4 (RIPK4)-deficient mice have epidermal defects and fusion of all external orifices. These are similar to Bartsocas-Papas syndrome and popliteal pterygium syndrome (PPS) in humans, for which causative mutations have been documented in the RIPK4 and IRF6 (interferon regulatory factor 6) gene, respectively. Although genetically distinct, these syndromes share the anomalies of marked pterygia, syndactyly, clefting and hypoplastic genitalia. Despite the strong resemblance of these two syndromes, no molecular connection between the transcription factor IRF6 and the kinase RIPK4 was known and the mechanism underlying the phenotype was unclear. Here we describe that RIPK4 deficiency in mice causes epithelial fusions associated with abnormal periderm development and aberrant ectopic localization of E-cadherin on the apical membrane of the outer peridermal cell layers. In Xenopus, RIPK4 depletion causes the absence of ectodermal epiboly and concomitant gastrulation defects that phenocopy ectopic expression of dominant-negative IRF6. We found that IRF6 controls RIPK4 expression and that wild-type, but not kinase-dead, RIPK4 can complement the gastrulation defect in Xenopus caused by IRF6 malfunctioning. In contrast to the mouse, we observed only minor effects on cadherin membrane expression in Xenopus RIPK4 morphants. However, gastrulation defects were associated with a virtual absence of cortical actin in the ectodermal cells that face the blastocoel cavity and this was phenocopied in embryos expressing dominant-negative IRF6. A role for RIPK4 in actin cytoskeleton organization was also revealed in mouse epidermis and in human epithelial HaCaT cells. In conclusion, we showed that in mice RIPK4 is implicated in cortical actin organization and in E-cadherin localization or function, which can explain the characteristic epithelial fusions observed in PPSs. In addition, we provide a novel molecular link between IRF6 and RIPK4 that unifies the different PPSs to a common molecular pathway.
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35
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Petridou NI, Skourides PA. FAK transduces extracellular forces that orient the mitotic spindle and control tissue morphogenesis. Nat Commun 2014; 5:5240. [PMID: 25341507 DOI: 10.1038/ncomms6240] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 09/11/2014] [Indexed: 01/08/2023] Open
Abstract
Spindle orientation is critical for proper morphogenesis of organs and tissues as well as for the maintenance of tissue morphology. Although significant progress has been made in understanding the mechanisms linking the cell cortex to the spindle and the well-documented role that extracellular forces play in spindle orientation, how such forces are transduced to the cortex remains poorly understood. Here we report that focal adhesion kinase (FAK) is necessary for correct spindle orientation and as a result, indispensable for proper epithelial morphogenesis in the vertebrate embryo. We show that FAK's role in spindle orientation is dependent on its ability to localize at focal adhesions and its interaction with paxillin, but is kinase activity independent. Finally, we present evidence that FAK is required for external force-induced spindle reorientation, suggesting that FAK's involvement in this process stems from a role in the transduction of external forces to the cell cortex.
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Affiliation(s)
- Nicoletta I Petridou
- Laboratory of Developmental Biology and BioImaging, Department of Biological Sciences, University of Cyprus, University Ave 1, Nicosia 2109, Cyprus
| | - Paris A Skourides
- Laboratory of Developmental Biology and BioImaging, Department of Biological Sciences, University of Cyprus, University Ave 1, Nicosia 2109, Cyprus
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36
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Ishida S, Tanaka R, Yamaguchi N, Ogata G, Mizutani T, Kawabata K, Haga H. Epithelial sheet folding induces lumen formation by Madin-Darby canine kidney cells in a collagen gel. PLoS One 2014; 9:e99655. [PMID: 25170757 PMCID: PMC4149355 DOI: 10.1371/journal.pone.0099655] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 06/18/2014] [Indexed: 11/19/2022] Open
Abstract
Lumen formation is important for morphogenesis; however, an unanswered question is whether it involves the collective migration of epithelial cells. Here, using a collagen gel overlay culture method, we show that Madin-Darby canine kidney cells migrated collectively and formed a luminal structure in a collagen gel. Immediately after the collagen gel overlay, an epithelial sheet folded from the periphery, migrated inwardly, and formed a luminal structure. The inhibition of integrin-β1 or Rac1 activity decreased the migration rate of the peripheral cells after the sheets folded. Moreover, lumen formation was perturbed by disruption of apical-basolateral polarity induced by transforming growth factor-β1. These results indicate that cell migration and cell polarity play an important role in folding. To further explore epithelial sheet folding, we developed a computer-simulated mechanical model based on the rigidity of the extracellular matrix. It indicated a soft substrate is required for the folding movement.
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Affiliation(s)
- Sumire Ishida
- Transdisciplinary Life Science Course, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Ryosuke Tanaka
- Transdisciplinary Life Science Course, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Naoya Yamaguchi
- Transdisciplinary Life Science Course, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Genki Ogata
- Transdisciplinary Life Science Course, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Takeomi Mizutani
- Transdisciplinary Life Science Course, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Kazushige Kawabata
- Transdisciplinary Life Science Course, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Hisashi Haga
- Transdisciplinary Life Science Course, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
- Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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37
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Bjerke MA, Dzamba BJ, Wang C, DeSimone DW. FAK is required for tension-dependent organization of collective cell movements in Xenopus mesendoderm. Dev Biol 2014; 394:340-56. [PMID: 25127991 DOI: 10.1016/j.ydbio.2014.07.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 07/04/2014] [Accepted: 07/30/2014] [Indexed: 12/21/2022]
Abstract
Collective cell movements are integral to biological processes such as embryonic development and wound healing and also have a prominent role in some metastatic cancers. In migrating Xenopus mesendoderm, traction forces are generated by cells through integrin-based adhesions and tension transmitted across cadherin adhesions. This is accompanied by assembly of a mechanoresponsive cadherin adhesion complex containing keratin intermediate filaments and the catenin-family member plakoglobin. We demonstrate that focal adhesion kinase (FAK), a major component of integrin adhesion complexes, is required for normal morphogenesis at gastrulation, closure of the anterior neural tube, axial elongation and somitogenesis. Depletion of zygotically expressed FAK results in disruption of mesendoderm tissue polarity similar to that observed when expression of keratin or plakoglobin is inhibited. Both individual and collective migrations of mesendoderm cells from FAK depleted embryos are slowed, cell protrusions are disordered, and cell spreading and traction forces are decreased. Additionally, keratin filaments fail to organize at the rear of cells in the tissue and association of plakoglobin with cadherin is diminished. These findings suggest that FAK is required for the tension-dependent assembly of the cadherin adhesion complex that guides collective mesendoderm migration, perhaps by modulating the dynamic balance of substrate traction forces and cell cohesion needed to establish cell polarity.
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Affiliation(s)
- Maureen A Bjerke
- Department of Cell Biology, School of Medicine, University of Virginia Health System, P.O.Box 800732, Charlottesville, VA 22908, USA
| | - Bette J Dzamba
- Department of Cell Biology, School of Medicine, University of Virginia Health System, P.O.Box 800732, Charlottesville, VA 22908, USA
| | - Chong Wang
- Department of Cell Biology, School of Medicine, University of Virginia Health System, P.O.Box 800732, Charlottesville, VA 22908, USA
| | - Douglas W DeSimone
- Department of Cell Biology, School of Medicine, University of Virginia Health System, P.O.Box 800732, Charlottesville, VA 22908, USA.
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38
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Abstract
Animal development requires a carefully orchestrated cascade of cell fate specification events and cellular movements. A surprisingly small number of choreographed cellular behaviours are used repeatedly to shape the animal body plan. Among these, cell intercalation lengthens or spreads a tissue at the expense of narrowing along an orthogonal axis. Key steps in the polarization of both mediolaterally and radially intercalating cells have now been clarified. In these different contexts, intercalation seems to require a distinct combination of mechanisms, including adhesive changes that allow cells to rearrange, cytoskeletal events through which cells exert the forces needed for cell neighbour exchange, and in some cases the regulation of these processes through planar cell polarity.
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39
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Plouhinec JL, Zakin L, Moriyama Y, De Robertis EM. Chordin forms a self-organizing morphogen gradient in the extracellular space between ectoderm and mesoderm in the Xenopus embryo. Proc Natl Acad Sci U S A 2013; 110:20372-9. [PMID: 24284174 PMCID: PMC3870759 DOI: 10.1073/pnas.1319745110] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The vertebrate body plan follows stereotypical dorsal-ventral (D-V) tissue differentiation controlled by bone morphogenetic proteins (BMPs) and secreted BMP antagonists, such as Chordin. The three germ layers--ectoderm, mesoderm, and endoderm--are affected coordinately by the Chordin-BMP morphogen system. However, extracellular morphogen gradients of endogenous proteins have not been directly visualized in vertebrate embryos to date. In this study, we improved immunolocalization methods in Xenopus embryos and analyzed the distribution of endogenous Chordin using a specific antibody. Chordin protein secreted by the dorsal Spemann organizer was found to diffuse along a narrow region that separates the ectoderm from the anterior endoderm and mesoderm. This Fibronectin-rich extracellular matrix is called "Brachet's cleft" in the Xenopus gastrula and is present in all vertebrate embryos. Chordin protein formed a smooth gradient that encircled the embryo, reaching the ventral-most Brachet cleft. Depletion with morpholino oligos showed that this extracellular gradient was regulated by the Chordin protease Tolloid and its inhibitor Sizzled. The Chordin gradient, as well as the BMP signaling gradient, was self-regulating and, importantly, was able to rescale in dorsal half-embryos. Transplantation of Spemann organizer tissue showed that Chordin diffused over long distances along this signaling highway between the ectoderm and mesoderm. Chordin protein must reach very high concentrations in this narrow region. We suggest that as ectoderm and mesoderm undergo morphogenetic movements during gastrulation, cells in both germ layers read their positional information coordinately from a single morphogen gradient located in Brachet's cleft.
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Affiliation(s)
- Jean-Louis Plouhinec
- Howard Hughes Medical Institute and
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095-1662
| | - Lise Zakin
- Howard Hughes Medical Institute and
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095-1662
| | - Yuki Moriyama
- Howard Hughes Medical Institute and
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095-1662
| | - Edward M. De Robertis
- Howard Hughes Medical Institute and
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095-1662
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40
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Abstract
Morphogenesis is the remarkable process by which cells self-assemble into complex tissues and organs that exhibit specialized form and function during embryological development. Many of the genes and chemical cues that mediate tissue and organ formation have been identified; however, these signals alone are not sufficient to explain how tissues and organs are constructed that exhibit their unique material properties and three-dimensional forms. Here, we review work that has revealed the central role that physical forces and extracellular matrix mechanics play in the control of cell fate switching, pattern formation, and tissue development in the embryo and how these same mechanical signals contribute to tissue homeostasis and developmental control throughout adult life.
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Affiliation(s)
- Tadanori Mammoto
- Vascular Biology Program, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115;
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41
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The interplay between cell signalling and mechanics in developmental processes. Nat Rev Genet 2013; 14:733-44. [PMID: 24045690 DOI: 10.1038/nrg3513] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Force production and the propagation of stress and strain within embryos and organisms are crucial physical processes that direct morphogenesis. In addition, there is mounting evidence that biomechanical cues created by these processes guide cell behaviours and cell fates. In this Review we discuss key roles for biomechanics during development to directly shape tissues, to provide positional information for cell fate decisions and to enable robust programmes of development. Several recently identified molecular mechanisms suggest how cells and tissues might coordinate their responses to biomechanical cues. Finally, we outline long-term challenges in integrating biomechanics with genetic analysis of developing embryos.
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42
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Syndecan-4 inhibits Wnt/β-catenin signaling through regulation of low-density-lipoprotein receptor-related protein (LRP6) and R-spondin 3. Int J Biochem Cell Biol 2013; 46:103-12. [PMID: 24275095 DOI: 10.1016/j.biocel.2013.11.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 10/18/2013] [Accepted: 11/06/2013] [Indexed: 11/21/2022]
Abstract
Regulation of Wnt signaling is crucial for embryonic development and adult homeostasis. Here we study the role of Syndecan-4 (SDC4), a cell-surface heparan sulphate proteoglycan, and Fibronectin (FN), in Wnt/β-catenin signaling. Gain- and loss-of-function experiments in mammalian cell lines and Xenopus embryos demonstrate that SDC4 and FN inhibit Wnt/β-catenin signaling. Epistatic and biochemical experiments show that this inhibition occurs at the cell membrane level through regulation of LRP6. R-spondin 3, a ligand that promotes canonical and non-canonical Wnt signaling, is more prone to potentiate Wnt/β-catenin signaling when SDC4 levels are reduced, suggesting a model whereby SDC4 tunes the ability of R-spondin to modulate the different Wnt signaling pathways. Since SDC4 has been previously related to non-canonical Wnt signaling, our results also suggest that this proteoglycan can be a key component in the regulation of Wnt signaling.
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43
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Planar cell polarity proteins differentially regulate extracellular matrix organization and assembly during zebrafish gastrulation. Dev Biol 2013; 383:39-51. [DOI: 10.1016/j.ydbio.2013.08.027] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 08/25/2013] [Accepted: 08/31/2013] [Indexed: 11/22/2022]
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44
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Petridou NI, Stylianou P, Skourides PA. A dominant-negative provides new insights into FAK regulation and function in early embryonic morphogenesis. Development 2013; 140:4266-76. [PMID: 24048589 DOI: 10.1242/dev.096073] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
FAK is a non-receptor tyrosine kinase involved in a wide variety of biological processes and crucial for embryonic development. In this manuscript, we report the generation of a new FAK dominant negative (FF), composed of the C terminus (FRNK) and the FERM domain of the protein. FF, unlike FRNK and FERM, mimics the localization of active FAK in the embryo, demonstrating that both domains are necessary to target FAK to its complexes in vivo. We show that the FERM domain has a role in the recruitment of FAK on focal adhesions and controls the dynamics of the protein on these complexes. Expression of FF blocks focal adhesion turnover and, unlike FRNK, acts as a dominant negative in vivo. FF expression in Xenopus results in an overall phenotype remarkably similar to the FAK knockout in mice, including loss of mesodermal tissues. Expression of FF in the animal cap revealed a previously unidentified role of FAK in early morphogenesis and specifically epiboly. We show that a fibronectin-derived signal transduced by FAK governs polarity and cell intercalation. Finally, failure of epiboly results in severe gastrulation problems that can be rescued by either mechanical or pharmacological relief of tension within the animal cap, demonstrating that epiboly is permissive for gastrulation. Overall, this work introduces a powerful new tool for the study of FAK, uncovers new roles for FAK in morphogenesis and reveals new mechanisms through which the FERM domain regulates the localization and dynamics of FAK.
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45
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Dray N, Lawton A, Nandi A, Jülich D, Emonet T, Holley SA. Cell-fibronectin interactions propel vertebrate trunk elongation via tissue mechanics. Curr Biol 2013; 23:1335-41. [PMID: 23810535 DOI: 10.1016/j.cub.2013.05.052] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 05/07/2013] [Accepted: 05/28/2013] [Indexed: 11/27/2022]
Abstract
During embryonic development and tissue homeostasis, cells produce and remodel the extracellular matrix (ECM). The ECM maintains tissue integrity and can serve as a substrate for cell migration. Integrin α5 (Itgα5) and αV (ItgαV) are the α subunits of the integrins most responsible for both cell adhesion to the ECM protein fibronectin (FN) and FN matrix fibrillogenesis. We perform a systems-level analysis of cell motion in the zebrafish tail bud during trunk elongation in the presence and absence of normal cell-FN interactions. Itgα5 and ItgαV have well-described roles in cell migration in vitro. However, we find that concomitant loss of itgα5 and itgαV leads to a trunk elongation defect without substantive alteration of cell migration. Tissue-specific transgenic rescue experiments suggest that the FN matrix on the surface of the paraxial mesoderm is required for body elongation via its role in defining tissue mechanics and intertissue adhesion.
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Affiliation(s)
- Nicolas Dray
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
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46
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Gee EPS, Yüksel D, Stultz CM, Ingber DE. SLLISWD sequence in the 10FNIII domain initiates fibronectin fibrillogenesis. J Biol Chem 2013; 288:21329-21340. [PMID: 23740248 DOI: 10.1074/jbc.m113.462077] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fibronectin (FN) assembly into extracellular matrix is tightly regulated and essential to embryogenesis and wound healing. FN fibrillogenesis is initiated by cytoskeleton-derived tensional forces transmitted across transmembrane integrins onto RGD binding sequences within the tenth FN type III (10FNIII) domains. These forces unfold 10FNIII to expose cryptic FN assembly sites; however, a specific sequence has not been identified in 10FNIII. Our past steered molecular dynamics simulations modeling 10FNIII unfolding by force at its RGD loop predicted a mechanical intermediate with a solvent-exposed N terminus spanning the A and B β-strands. Here, we experimentally confirm that the predicted 23-residue cryptic peptide 1 (CP1) initiates FN multimerization, which is mediated by interactions with 10FNIII that expose hydrophobic surfaces that support 8-anilino-1-napthalenesulfonic acid binding. Localization of multimerization activity to the C terminus led to the discovery of a minimal 7-amino acid "multimerization sequence" (SLLISWD), which induces polymerization of FN and the clotting protein fibrinogen in addition to enhancing FN fibrillogenesis in fibroblasts. A point mutation at Trp-6 that reduces exposure of hydrophobic sites for 8-anilino-1-napthalenesulfonic acid binding and β-structure formation inhibits FN multimerization and prevents physiological cell-based FN assembly in culture. We propose a model for cell-mediated fibrillogenesis whereby cell traction force initiates a cascade of intermolecular exchange starting with the unfolding of 10FNIII to expose the multimerization sequence, which interacts with strand B of another 10FNIII domain via a Trp-mediated β-strand exchange to stabilize a partially unfolded intermediate that propagates FN self-assembly.
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Affiliation(s)
- Elaine P S Gee
- From the Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115
| | - Deniz Yüksel
- From the Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115,; the Vascular Biology Program and Departments of Pathology and Surgery, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115
| | - Collin M Stultz
- the Institute of Medical Engineering and Sciences, Department of Electrical Engineering and Computer Science, and the Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and
| | - Donald E Ingber
- From the Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115,; the Vascular Biology Program and Departments of Pathology and Surgery, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115,; the Harvard School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138.
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Song S, Eckerle S, Onichtchouk D, Marrs JA, Nitschke R, Driever W. Pou5f1-dependent EGF expression controls E-cadherin endocytosis, cell adhesion, and zebrafish epiboly movements. Dev Cell 2013; 24:486-501. [PMID: 23484854 DOI: 10.1016/j.devcel.2013.01.016] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 10/31/2012] [Accepted: 01/19/2013] [Indexed: 01/05/2023]
Abstract
Initiation of motile cell behavior in embryonic development occurs during late blastula stages when gastrulation begins. At this stage, the strong adhesion of blastomeres has to be modulated to enable dynamic behavior, similar to epithelial-to-mesenchymal transitions. We show that, in zebrafish maternal and zygotic (MZ)spg embryos mutant for the stem cell transcription factor Pou5f1/Oct4, which are severely delayed in the epiboly gastrulation movement, all blastomeres are defective in E-cadherin (E-cad) endosomal trafficking, and E-cad accumulates at the plasma membrane. We find that Pou5f1-dependent control of EGF expression regulates endosomal E-cad trafficking. EGF receptor may act via modulation of p120 activity. Loss of E-cad dynamics reduces cohesion of cells in reaggregation assays. Quantitative analysis of cell behavior indicates that dynamic E-cad endosomal trafficking is required for epiboly cell movements. We hypothesize that dynamic control of E-cad trafficking is essential to effectively generate new adhesion sites when cells move relative to each other.
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Affiliation(s)
- Sungmin Song
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany
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Spindle position in symmetric cell divisions during epiboly is controlled by opposing and dynamic apicobasal forces. Dev Cell 2012; 22:775-87. [PMID: 22406140 PMCID: PMC3332010 DOI: 10.1016/j.devcel.2012.01.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 11/08/2011] [Accepted: 01/11/2012] [Indexed: 11/21/2022]
Abstract
Orientation of cell division is a vital aspect of tissue morphogenesis and growth. Asymmetric divisions generate cell fate diversity and epithelial stratification, whereas symmetric divisions contribute to tissue growth, spreading, and elongation. Here, we describe a mechanism for positioning the spindle in symmetric cell divisions of an embryonic epithelium. We show that during the early stages of epiboly, spindles in the epithelium display dynamic behavior within the plane of the epithelium but are kept firmly within this plane to give a symmetric division. This dynamic stability relies on balancing counteracting forces: an apically directed force exerted by F-actin/myosin-2 via active cortical flow and a basally directed force mediated by microtubules and myosin-10. When both forces are disrupted, spindle orientation deviates from the epithelial plane, and epithelial surface is reduced. We propose that this dynamic mechanism maintains symmetric divisions while allowing the quick adjustment of division plane to facilitate even tissue spreading.
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Zou L, Cao S, Kang N, Huebert RC, Shah VH. Fibronectin induces endothelial cell migration through β1 integrin and Src-dependent phosphorylation of fibroblast growth factor receptor-1 at tyrosines 653/654 and 766. J Biol Chem 2012; 287:7190-202. [PMID: 22247553 DOI: 10.1074/jbc.m111.304972] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The extracellular matrix microenvironment regulates cell phenotype and function. One mechanism by which this is achieved is the transactivation of receptor tyrosine kinases by specific matrix molecules. Here, we demonstrate that the provisional matrix protein, fibronectin (FN), activates fibroblast growth factor (FGF) receptor-1 (FGFR1) independent of FGF ligand in liver endothelial cells. FN activation of FGFR1 requires β1 integrin, as evidenced by neutralizing antibody and siRNA-based studies. Complementary genetic and pharmacologic approaches identify that the non-receptor tyrosine kinase Src is required for FN transactivation of FGFR1. Whereas FGF ligand-induced phosphorylation of FGFR1 preferentially activates ERK, FN-induced phosphorylation of FGFR1 preferentially activates AKT, indicating differential downstream signaling of FGFR1 in response to alternate stimuli. Mutation analysis of known tyrosine residues of FGFR1 reveals that tyrosine 653/654 and 766 residues are required for FN-FGFR1 activation of AKT and chemotaxis. Thus, our study mechanistically dissects a new signaling pathway by which FN achieves endothelial cell chemotaxis, demonstrates how differential phosphorylation profiles of FGFR1 can achieve alternate downstream signals, and, more broadly, highlights the diversity of mechanisms by which the extracellular matrix microenvironment regulates cell behavior through transactivation of receptor tyrosine kinases.
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Affiliation(s)
- Li Zou
- Gastroenterology Research Unit and Cancer Cell Biology Program, Mayo Clinic, Rochester, Minnesota 55905, USA
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Chen Y, Legan SK, Mahan A, Thornton J, Xu H, Schwarz MA. Endothelial-monocyte activating polypeptide II disrupts alveolar epithelial type II to type I cell transdifferentiation. Respir Res 2012; 13:1. [PMID: 22214516 PMCID: PMC3295640 DOI: 10.1186/1465-9921-13-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 01/03/2012] [Indexed: 11/13/2022] Open
Abstract
Background Distal alveolar morphogenesis is marked by differentiation of alveolar type (AT)-II to AT-I cells that give rise to the primary site of gas exchange, the alveolar/vascular interface. Endothelial-Monocyte Activating Polypeptide (EMAP) II, an endogenous protein with anti-angiogenic properties, profoundly disrupts distal lung neovascularization and alveolar formation during lung morphogenesis, and is robustly expressed in the dysplastic alveolar regions of infants with Bronchopulmonary dysplasia. Determination as to whether EMAP II has a direct or indirect affect on ATII→ATI trans-differentiation has not been explored. Method In a controlled nonvascular environment, an in vitro model of ATII→ATI cell trans-differentiation was utilized to demonstrate the contribution that one vascular mediator has on distal epithelial cell differentiation. Results Here, we show that EMAP II significantly blocked ATII→ATI cell transdifferentiation by increasing cellular apoptosis and inhibiting expression of ATI markers. Moreover, EMAP II-treated ATII cells displayed myofibroblast characteristics, including elevated cellular proliferation, increased actin cytoskeleton stress fibers and Rho-GTPase activity, and increased nuclear:cytoplasmic volume. However, EMAP II-treated cells did not express the myofibroblast markers desmin or αSMA. Conclusion Our findings demonstrate that EMAP II interferes with ATII → ATI transdifferentiation resulting in a proliferating non-myofibroblast cell. These data identify the transdifferentiating alveolar cell as a possible target for EMAP II's induction of alveolar dysplasia.
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Affiliation(s)
- Yao Chen
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, TX, USA
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