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Chakraborty S, Peak KE, Gleghorn JP, Carroll TJ, Varner VD. Quantifying Spatial Patterns of Tissue Stiffness Within the Embryonic Mouse Kidney. Methods Mol Biol 2024; 2805:171-186. [PMID: 39008182 DOI: 10.1007/978-1-0716-3854-5_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
Biophysical factors, including changes in mechanical stiffness, have been shown to influence the morphogenesis of developing organs. There is a lack of experimental techniques, however, that can probe the mechanical properties of embryonic tissues-especially those which are not mechanically or optically accessible, such as the visceral organs of the developing mouse embryo. Here, using the embryonic kidney as a model system, we describe a method to use microindentation to quantify tissue-level regional differences in the mechanical properties of an embryonic organ. This technique is generalizable and can be used to quantify patterns of tissue stiffness within other developing organ systems. Going forward, these data will enable new experimental studies of the role of biophysical cues during organogenesis.
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Affiliation(s)
- Somdutta Chakraborty
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA
| | - Kara E Peak
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA
| | - Jason P Gleghorn
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
| | - Thomas J Carroll
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX, USA
- Department of Internal Medicine, Division of Nephrology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Victor D Varner
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA.
- Department of Biomedical Engineering, UT Southwestern Medical Center, Dallas, TX, USA.
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2
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Udoumoh AF, Igwebuike UM, Nwaogu IC, Obidike IR. Morphological features of the late-embryo-stage gastrointestinal tract of free-roaming light ecotype Nigerian indigenous chicken. Anat Histol Embryol 2024; 53:e13007. [PMID: 38069839 DOI: 10.1111/ahe.13007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 11/01/2023] [Accepted: 11/30/2023] [Indexed: 01/18/2024]
Abstract
Morphological changes in the late-embryo-stage gastrointestinal tract of Nigerian indigenous chicken were investigated using anatomical techniques. The paraffin-embedded sections were stained with haematoxylin and eosin and periodic acid Schiff-Alcian blue (pH 2.5) stains. During the late pre-hatch period, the framework of the stomach was already established, but glands were yet poorly developed. Randomly oriented pre-glandular cells in the lamina propria mucosae at embryonic day (ED) 14 became organized into elongated simple tubular glands at ED 19 and assumed adult morphology at post-hatch day (PD) 1. Acidic and neutral mucin deposits were associated with the glandular cells. In the small intestine, enterocytes of the tunica epithelialis mucosae transformed from cuboidal-shaped cells (at ED 14) to tall columnar cells (at PD 1). Short crypts of Lieberkühn, goblet cells, microfold cells and enteroendocrine cells were evident at ED 19, while the lamina propria mucosae and submucosa contained mesenchymal cells, reticular cells and isolated lymphoblasts. Similarly, the crypts, lymphoblasts, mesenchymal and reticular cells were also associated with the lamina propria mucosae and submucosa of the caecum and colorectum at ED 19. It was inferred from these findings that extensive cellular and tissue modifications occur in the gastrointestinal tract within the narrow window of the late pre-hatch period. The definitive gut tunics, epithelium, glandular tissues, immune-competent cells and tissues are formed as a result. Thus, the embryonic gut of the bird is made capable of assuming its necessary functions of food digestion, nutrient absorption, water and ion re-absorption, immune surveillance, antibody production and immune responses at hatch.
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Affiliation(s)
- Anietie Francis Udoumoh
- Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Udensi Maduabuchi Igwebuike
- Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Innocent Chima Nwaogu
- Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Ikechukwu Reginald Obidike
- Department of Veterinary Physiology and Pharmacology, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Enugu State, Nigeria
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3
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Hack JM, Anwar NZ, Jackson JG, Furth ME, Varner VD. Quantifying endodermal strains during heart tube formation in the developing chicken embryo. J Biomech 2023; 149:111481. [PMID: 36787674 PMCID: PMC10163833 DOI: 10.1016/j.jbiomech.2023.111481] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 12/17/2022] [Accepted: 02/01/2023] [Indexed: 02/09/2023]
Abstract
In the early avian embryo, the developing heart forms when bilateral fields of cardiac progenitor cells, which reside in the lateral plate mesoderm, move toward the embryonic midline, and fuse above the anterior intestinal portal (AIP) to form a straight, muscle-wrapped tube. During this process, the precardiac mesoderm remains in close contact with the underlying endoderm. Previous work has shown that the endoderm around the AIP actively contracts to pull the cardiac progenitors toward the midline. The morphogenetic deformations associated with this endodermal convergence, however, remain unclear, as do the signaling pathways that might regulate this process. Here, we fluorescently labeled populations of endodermal cells in early chicken embryos and tracked their motion during heart tube formation to compute time-varying strains along the anterior endoderm. We then determined how the computed endodermal strain distributions are affected by the pharmacological inhibition of either myosin II or fibroblast growth factor (FGF) signaling. Our data indicate that a mediolateral gradient in endodermal shortening is present around the AIP, as well as substantial convergence and extension movements both anterior and lateral to the AIP. These active endodermal deformations are disrupted if either actomyosin contractility or FGF signaling are inhibited pharmacologically. Taken together, these results demonstrate how active deformations along the anterior endoderm contribute to heart tube formation within the developing embryo.
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Affiliation(s)
- Joshua M Hack
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, United States
| | - Nareen Z Anwar
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, United States
| | - John G Jackson
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, United States
| | - Meagan E Furth
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, United States
| | - Victor D Varner
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, United States; Department of Surgery, UT Southwestern Medical Center, Dallas, TX, United States.
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Patil LS, Varner VD. Toward Measuring the Mechanical Stresses Exerted by Branching Embryonic Airway Epithelial Explants in 3D Matrices of Matrigel. Ann Biomed Eng 2022; 50:1143-1157. [PMID: 35718813 PMCID: PMC9590229 DOI: 10.1007/s10439-022-02989-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 06/03/2022] [Indexed: 11/01/2022]
Abstract
Numerous organs in the bodies of animals, including the lung, kidney, and mammary gland, contain ramified networks of epithelial tubes. These structures arise during development via a process known as branching morphogenesis. Previous studies have shown that mechanical forces directly impact this process, but the patterns of mechanical stress exerted by branching embryonic epithelia are not well understood. This is, in part, owing to a lack of experimental tools. Traditional traction force microscopy assays rely on the use of compliant hydrogels with well-defined mechanical properties. Isolated embryonic epithelial explants, however, have only been shown to branch in three-dimensional matrices of reconstituted basement membrane protein, or Matrigel, a biomaterial with poorly characterized mechanical behavior, especially in the regime of large deformations. Here, to compute the traction stresses generated by branching epithelial explants, we quantified the finite-deformation constitutive behavior of gels of reconstituted basement membrane protein subjected to multi-axial mechanical loads. We then modified the mesenchyme-free assay for the ex vivo culture of isolated embryonic airway epithelial explants by suspending fluorescent microspheres within the surrounding gel and tracking their motion during culture. Surprisingly, the tracked bead motion was non-zero in regions of the gel far away from the explants, suggestive of passive swelling deformations within the matrix. To compute accurate traction stresses, these swelling deformations must be decomposed from those generated by the branching explants. We thus tracked the motion of beads suspended within cell-free matrices and quantified spatiotemporal patterns of gel swelling. Taken together, these passive swelling data can be combined with the measured mechanical properties of the gel to compute the traction forces exerted by intact embryonic epithelial explants.
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Affiliation(s)
- Lokesh S Patil
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA
| | - Victor D Varner
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA.
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX, USA.
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5
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The Mammary Gland: Basic Structure and Molecular Signaling during Development. Int J Mol Sci 2022; 23:ijms23073883. [PMID: 35409243 PMCID: PMC8998991 DOI: 10.3390/ijms23073883] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/22/2022] [Accepted: 03/30/2022] [Indexed: 01/27/2023] Open
Abstract
The mammary gland is a compound, branched tubuloalveolar structure and a major characteristic of mammals. The mammary gland has evolved from epidermal apocrine glands, the skin glands as an accessory reproductive organ to support postnatal survival of offspring by producing milk as a source of nutrition. The mammary gland development begins during embryogenesis as a rudimentary structure that grows into an elementary branched ductal tree and is embedded in one end of a larger mammary fat pad at birth. At the onset of ovarian function at puberty, the rudimentary ductal system undergoes dramatic morphogenetic change with ductal elongation and branching. During pregnancy, the alveolar differentiation and tertiary branching are completed, and during lactation, the mature milk-producing glands eventually develop. The early stages of mammary development are hormonal independent, whereas during puberty and pregnancy, mammary gland development is hormonal dependent. We highlight the current understanding of molecular regulators involved during different stages of mammary gland development.
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Pokhrel N, Genin O, Sela-Donenfeld D, Cinnamon Y. HREM, RNAseq and Cell Cycle Analyses Reveal the Role of the G2/M-Regulatory Protein, WEE1, on the Survivability of Chicken Embryos during Diapause. Biomedicines 2022; 10:779. [PMID: 35453529 PMCID: PMC9033001 DOI: 10.3390/biomedicines10040779] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 03/15/2022] [Accepted: 03/22/2022] [Indexed: 02/04/2023] Open
Abstract
Avian blastoderm can enter into diapause when kept at low temperatures and successfully resume development (SRD) when re-incubated in body temperature. These abilities, which are largely affected by the temperature and duration of the diapause, are poorly understood at the cellular and molecular level. To determine how temperature affects embryonic morphology during diapause, high-resolution episcopic microscopy (HREM) analysis was utilized. While blastoderms diapausing at 12 °C for 28 days presented typical cytoarchitecture, similar to non-diapaused embryos, at 18 °C, much thicker blastoderms with higher cell number were observed. RNAseq was conducted to discover the genes underlying these phenotypes, revealing differentially expressed cell cycle regulatory genes. Among them, WEE1, a negative regulator of G2/M transition, was highly expressed at 12 °C compared to 18 °C. This finding suggested that cells at 12 °C are arrested at the G2/M phase, as supported by bromodeoxyuridine incorporation (BrdU) assay and phospho-histone H3 (pH 3) immunostaining. Inhibition of WEE1 during diapause at 12 °C resulted in cell cycle progression beyond the G2/M and augmented tissue volume, resembling the morphology of 18 °C-diapaused embryos. These findings suggest that diapause at low temperatures leads to WEE1 upregulation, which arrests the cell cycle at the G2/M phase, promoting the perseverance of embryonic cytoarchitecture and future SRD. In contrast, WEE1 is not upregulated during diapause at higher temperature, leading to continuous proliferation and maladaptive morphology associated with poor survivability. Combining HREM-based analysis with RNAseq and molecular manipulations, we present a novel mechanism that regulates the ability of diapaused avian embryos to maintain their cytoarchitecture via cell cycle arrest, which enables their SRD.
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Affiliation(s)
- Narayan Pokhrel
- Agriculture Research Organization, The Volcani Center, Department of Poultry and Aquaculture Science, Bet Dagan 50250, Israel; (N.P.); (O.G.)
- The Robert H. Smith Faculty of Agriculture, Food and Environment, Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Olga Genin
- Agriculture Research Organization, The Volcani Center, Department of Poultry and Aquaculture Science, Bet Dagan 50250, Israel; (N.P.); (O.G.)
| | - Dalit Sela-Donenfeld
- The Robert H. Smith Faculty of Agriculture, Food and Environment, Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Yuval Cinnamon
- Agriculture Research Organization, The Volcani Center, Department of Poultry and Aquaculture Science, Bet Dagan 50250, Israel; (N.P.); (O.G.)
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Khan SA, Khan S, Muhammad N, Rehman ZU, Khan MA, Nasir A, Kalsoom UE, Khan AK, Khan H, Wasif N. The First Report of a Missense Variant in RFX2 Causing Non-Syndromic Tooth Agenesis in a Consanguineous Pakistani Family. Front Genet 2022; 12:782653. [PMID: 35145545 PMCID: PMC8822170 DOI: 10.3389/fgene.2021.782653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
Background: The syndromic and non-syndromic congenital missing teeth phenotype is termed tooth agenesis. Since tooth agenesis is a heterogeneous disorder hence, the patients show diverse absent teeth phenotypes. Thus identifying novel genes involved in the morphogenesis of ectodermal appendages, including teeth, paves the way for establishing signaling pathways.Methods and Results: We have recruited an autosomal recessive non-syndromic tooth agenesis family with two affected members. The exome sequencing technology identified a novel missense sequence variant c.1421T > C; p.(Ile474Thr) in a regulatory factor X (RFX) family member (RFX2, OMIM: 142,765). During the data analysis eight rare variants on various chromosomal locations were identified, but the co-segregation analysis using Sanger sequencing confirmed the segregation of only two variants RFX2: c.1421T > C; p.(Ile474Thr), DOHH: c.109C > G; p.(Pro37Ala) lying in a common 7.1 MB region of homozygosity on chromosome 19p13.3. Furthermore, the online protein prediction algorithms and protein modeling analysis verified the RFX2 variant as a damaging genetic alteration and ACMG pathogenicity criteria classified it as likely pathogenic. On the other hand, the DOHH variant showed benign outcomes.Conclusion:RFX2 regulates the Hedgehog and fibroblast growth factor signaling pathways, which are involved in the epithelial and mesenchymal interactions during tooth development. Prior animal model studies have confirmed the expression of rfx2 at a developmental stage governing mouth formation. Moreover, its regulatory role and close association with ciliary and non-ciliary genes causing various dental malformations makes it a potential candidate gene for tooth agenesis phenotype. Further studies will contribute to exploring the direct role of RFX2 in human tooth development.
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Affiliation(s)
- Sher Alam Khan
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology (KUST), Kohat, Pakistan
| | - Saadullah Khan
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology (KUST), Kohat, Pakistan
- *Correspondence: Saadullah Khan, ; Naveed Wasif,
| | - Noor Muhammad
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology (KUST), Kohat, Pakistan
| | - Zia Ur Rehman
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology (KUST), Kohat, Pakistan
| | - Muhammad Adnan Khan
- Dental Material, Institute of Basic Medical Sciences, Khyber Medical University Peshawar, Peshawar, Pakistan
| | - Abdul Nasir
- Department of Molecular Science and Technology, Ajou University, Suwon, South Korea
| | - Umm-e- Kalsoom
- Department of Biochemistry, Hazara University, Mansehra, Pakistan
| | - Anwar Kamal Khan
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology (KUST), Kohat, Pakistan
| | - Hassan Khan
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology (KUST), Kohat, Pakistan
| | - Naveed Wasif
- Institute of Human Genetics, University of Ulm, Ulm, Germany
- Institute of Human Genetics, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
- *Correspondence: Saadullah Khan, ; Naveed Wasif,
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8
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Sun SY, Feng XQ. Fluid-solid coupling dynamic model for oscillatory growth of multicellular lumens. J Biomech 2021; 131:110937. [PMID: 34972017 DOI: 10.1016/j.jbiomech.2021.110937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 12/18/2021] [Accepted: 12/20/2021] [Indexed: 11/15/2022]
Abstract
The development of multicellular lumens involves the interplay of cell proliferation, oscillation, and fluid transport. In this paper, a fluid-solid coupling dynamic model is proposed to investigate the physical mechanisms underlying the oscillatory growth of lumens. On the basis of experimental observations, the periodic oscillation of a lumen is interpreted by the fracturing-healing mechanism of cell-cell contacts, which induces a hydraulic-controlled outward flow switch. This model reproduces the oscillations of lumen sizes, in agreement with the experimental results of Hydra regeneration. It is found that the overall change trend of the lumen volume is determined by the tissue development induced by cell proliferation and the fluid transport induced by the osmotic pressure, while the outward flow due to the fracturing of cell-cell contacts regulates the oscillatory volume and the stress level in an appropriate scope. This work not only deepens our understanding of biomechanical mechanisms under the development of fluid-containing lumens, but also provides a theoretical framework to rationalize the dynamics of lumen-like tissues.
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Affiliation(s)
- Shu-Yi Sun
- Institute of Biomechanics and Medical Engineering, AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
| | - Xi-Qiao Feng
- Institute of Biomechanics and Medical Engineering, AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China; State Key Lab of Tribology, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
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9
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Udoumoh AF, Nwaogu IC, Igwebuike UM, Obidike IR. Light and transmission electron microscopic evaluation of the lamina epithelialis mucosae in the ileum of pre- and post-hatch broiler chicken. Anat Histol Embryol 2021; 51:136-142. [PMID: 34877705 DOI: 10.1111/ahe.12774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 11/24/2021] [Accepted: 11/30/2021] [Indexed: 11/29/2022]
Abstract
Morphological development of the lamina epithelialis mucosae (LEM) of the ileum of broiler chicken was evaluated using light and transmission electron microscopic techniques. Ileal sections were collected on embryonic days (ED) 14, 17 and 19, as well as post-hatch days (PD) 1, 3, 5, 7, 14, 21, 28, 35, 42 and 56. The result showed that the ileal LEM, which were poorly defined at embryonic days 14 and 17, consisted of enterocytes and some atypically shaped goblet cells. Apico-lateral tight junctions and irregularly shaped microvilli were associated with the enterocytes at ED 14 and 17. The enterocyte microvilli were more uniform in shape and distribution at ED 19. The embryonic goblet cells were varied in shape and possessed basally displaced, star-shaped nuclei and small apical cytoplasmic vacuoles. During the post-hatch ages, the LEM was a typical epithelium with a single layer of columnar-shaped enterocytes that became highly elongated at post-hatch day (PD) 7. The goblet cells were characteristically 'wine-glass' shaped. Follicle-associated epithelium (FAE) showing numerous lymphocytes among the enterocytes occurred in the post-hatch LEM. The intra-epithelial lymphocytes (IEL) were first encountered at PD 1, but increased several folds within the first two weeks post-hatch. Entero-endocrine cells were observed in the epithelium from PD 21. Finally, from this study, it is obvious that enterocytes and small atypically shaped goblet cells occur in the ileal LEM during the pre-hatch period, but these cells assume adult morphological characteristics after hatch. Thus, the cells of the ileal LEM play strategic absorptive, secretory and protective roles in the gut.
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Affiliation(s)
- Anietie Francis Udoumoh
- Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Nigeria
| | - Innocent Chima Nwaogu
- Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Nigeria
| | | | - Ikechukwu Reginald Obidike
- Department of Veterinary Physiology and Pharmacology, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Nigeria
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Potter MJ, Richardson WJ. Fabrication and characterization methods for investigating cell-matrix interactions in environments possessing spatial orientation heterogeneity. Acta Biomater 2021; 136:420-428. [PMID: 34601105 PMCID: PMC8627456 DOI: 10.1016/j.actbio.2021.09.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 11/29/2022]
Abstract
Fibrillar collagen is a ubiquitous structural protein that plays a significant role in determining the mechanical properties of various tissues. The constituent collagen architecture can give direct insight into the respective functional role of the tissue due to the strong structure-function relationship that is exhibited. In such tissues, matrix structure can vary across local subregions contributing to mechanical heterogeneity which can be implicated in tissue function or failure. The post-myocardial infarction scar environment is an example of note where mechanically insufficient collagen can result in impaired cardiac function and possibly tissue rupture due to post-MI cellular response and matrix interactions. In order to further develop the understanding of cell-matrix interactions within heterogeneous environments, we developed a method of heterogeneous collagen gel fabrication which produces a region of randomly oriented fibers directly adjacent to an interconnected region of anisotropic alignment. To fully capture and evaluate the degree of alignment and spatial orientation heterogeneity, several image processing and automated analysis methods were employed. Our analysis revealed the successful fabrication of an interconnected spatially heterogeneous collagen gel possessing distinct regions of random or preferential alignment. Additionally, embedded cell populations were observed to recognize and reorient with their underlying and surrounding architectures through our cell-centric analysis techniques. STATEMENT OF SIGNIFICANCE: Fibrillar collagen is a structural protein that contributes to the architecture-function relationship exhibited by various tissues where mechanically insufficient collagen architecture can lead to tissue failure. One environment where this can occur is the post-myocardial infarction scar environment where too much or too little collagen accumulation coupled with spatial fiber orientation heterogeneity can lead to environments incapable of normal mechanical functionality. While there are methodologies capable of generating aligned constructs, they do so with varying degrees of control and complexity with many producing uniform construct alignment. The presented platform is simple and produces continuous constructs possessing inherent spatial orientation heterogeneity. Coupling this with image processing and automated analysis methods enables the probing of fundamental cell-matrix interactions within heterogeneous environments.
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Affiliation(s)
- Michael J Potter
- Department of Bioengineering, 301 Rhodes Research Center Clemson University, Clemson, SC, USA.
| | - William J Richardson
- Department of Bioengineering, 301 Rhodes Research Center Clemson University, Clemson, SC, USA; Biomedical Data Science & Informatics Program, Clemson University, Clemson, SC, USA.
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11
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Wang JX, White MD. Mechanical forces in avian embryo development. Semin Cell Dev Biol 2021; 120:133-146. [PMID: 34147339 DOI: 10.1016/j.semcdb.2021.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/27/2021] [Accepted: 06/02/2021] [Indexed: 10/21/2022]
Abstract
Research using avian embryos has led to major conceptual advances in developmental biology, virology, immunology, genetics and cell biology. The avian embryo has several significant advantages, including ready availability and ease of accessibility, rapid development with marked similarities to mammals and a high amenability to manipulation. As mechanical forces are increasingly recognised as key drivers of morphogenesis, this powerful model system is shedding new light on the mechanobiology of embryonic development. Here, we highlight progress in understanding how mechanical forces direct key morphogenetic processes in the early avian embryo. Recent advances in quantitative live imaging and modelling are elaborating upon traditional work using physical models and embryo manipulations to reveal cell dynamics and tissue forces in ever greater detail. The recent application of transgenic technologies further increases the strength of the avian model and is providing important insights about previously intractable developmental processes.
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Affiliation(s)
- Jian Xiong Wang
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, QLD 4072, Australia
| | - Melanie D White
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, QLD 4072, Australia.
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12
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Fleury V, Peaucelle A, Abourachid A, Plateau O. Second-order division in sectors as a prepattern for sensory organs in vertebrate development. Theory Biosci 2021; 141:141-163. [PMID: 34128197 DOI: 10.1007/s12064-021-00350-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 05/18/2021] [Indexed: 11/24/2022]
Abstract
We present in vivo observations of chicken embryo development which show that the early chicken embryo presents a principal structure made out of concentric rings and a secondary structure composed of radial sectors. During development, physical forces deform the main rings into axially directed, antero-posterior tubes, while the sectors roll up to form cylinders that are perpendicular to the antero-posterior axis. As a consequence, the basic structure of the chicken embryo is a series of encased antero-posterior tubes (gut, neural tube, body envelope, amnion, chorion) decorated with smaller orifices (ear duct, eye stalk, nasal duct, gills, mouth) forming at right angles to the main body axis. We argue that the second-order divisions reflect the early pattern of cell cleavage, and that the transformation of radial and orthoradial lines into a body with sensory organs is a generic biophysical mechanism more general than the chicken embryo.
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Affiliation(s)
- Vincent Fleury
- Laboratoire Matière et Systèmes Complexes, UMR 7057, Université de Paris/CNRS, 10 rue Alice Domont et Léonie Duquet, 75013, Paris, France.
| | - Alexis Peaucelle
- UMR 1318, Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
| | - Anick Abourachid
- Laboratoire Mécanismes Adaptatifs et Evolution, UMR 7179 MNHN, CNRS, CP 55, 57 rue Cuvier, 75231, Paris cedex 05, France
| | - Olivia Plateau
- Laboratoire Matière et Systèmes Complexes, UMR 7057, Université de Paris/CNRS, 10 rue Alice Domont et Léonie Duquet, 75013, Paris, France.,Laboratoire Mécanismes Adaptatifs et Evolution, UMR 7179 MNHN, CNRS, CP 55, 57 rue Cuvier, 75231, Paris cedex 05, France.,Département de Géosciences, Université de Fribourg, Ch. du Musée 6, 1700, Fribourg, Switzerland
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13
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Akos Z, Isai DG, Rajasingh S, Kosa E, Ghazvini S, Dhar P, Czirok A. Viscoelastic Properties of ECM-Rich Embryonic Microenvironments. Front Cell Dev Biol 2020; 8:674. [PMID: 32984301 PMCID: PMC7487363 DOI: 10.3389/fcell.2020.00674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Accepted: 07/02/2020] [Indexed: 11/13/2022] Open
Abstract
The material properties of tissues and their mechanical state is an important factor in development, disease, regenerative medicine and tissue engineering. Here we describe a microrheological measurement technique utilizing aggregates of microinjected ferromagnetic nickel particles to probe the viscoelastic properties of embryonic tissues. Quail embryos were cultured in a plastic incubator chamber located at the center of two pairs of crossed electromagnets. We found a pronounced viscoelastic behavior within the ECM-rich region separating the mesoderm and endoderm in Hamburger Hamilton stage 10 quail embryos, consistent with a Zener (standard generalized solid) model. The viscoelastic response is about 45% of the total response, with a characteristic relaxation time of 1.3 s.
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Affiliation(s)
- Zsuzsa Akos
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Dona Greta Isai
- Department of Anatomy & Cell Biology, University of Kansas Medical Center, Kansas City, KS, United States
| | - Sheeja Rajasingh
- Department of Bioscience Research, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Edina Kosa
- Department of Research, Kansas City University of Medicine and Biosciences, Kansas City, MO, United States
| | - Saba Ghazvini
- Chemical & Petroleum Engineering, The University of Kansas, Lawrence, KS, United States
| | - Prajnaparamita Dhar
- Chemical & Petroleum Engineering, The University of Kansas, Lawrence, KS, United States
| | - Andras Czirok
- Department of Anatomy & Cell Biology, University of Kansas Medical Center, Kansas City, KS, United States.,Department of Biological Physics, Eotvos University, Budapest, Hungary
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14
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Follow Me! A Tale of Avian Heart Development with Comparisons to Mammal Heart Development. J Cardiovasc Dev Dis 2020; 7:jcdd7010008. [PMID: 32156044 PMCID: PMC7151090 DOI: 10.3390/jcdd7010008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/16/2020] [Accepted: 02/21/2020] [Indexed: 12/19/2022] Open
Abstract
Avian embryos have been used for centuries to study development due to the ease of access. Because the embryos are sheltered inside the eggshell, a small window in the shell is ideal for visualizing the embryos and performing different interventions. The window can then be covered, and the embryo returned to the incubator for the desired amount of time, and observed during further development. Up to about 4 days of chicken development (out of 21 days of incubation), when the egg is opened the embryo is on top of the yolk, and its heart is on top of its body. This allows easy imaging of heart formation and heart development using non-invasive techniques, including regular optical microscopy. After day 4, the embryo starts sinking into the yolk, but still imaging technologies, such as ultrasound, can tomographically image the embryo and its heart in vivo. Importantly, because like the human heart the avian heart develops into a four-chambered heart with valves, heart malformations and pathologies that human babies suffer can be replicated in avian embryos, allowing a unique developmental window into human congenital heart disease. Here, we review avian heart formation and provide comparisons to the mammalian heart.
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15
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Méhes E, Biri-Kovács B, Isai DG, Gulyás M, Nyitray L, Czirók A. Matrigel patterning reflects multicellular contractility. PLoS Comput Biol 2019; 15:e1007431. [PMID: 31652274 PMCID: PMC6834294 DOI: 10.1371/journal.pcbi.1007431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 11/06/2019] [Accepted: 09/24/2019] [Indexed: 01/13/2023] Open
Abstract
Non-muscle myosin II (NMII)-induced multicellular contractility is essential for development, maintenance and remodeling of tissue morphologies. Dysregulation of the cytoskeleton can lead to birth defects or enable cancer progression. We demonstrate that the Matrigel patterning assay, widely used to characterize endothelial cells, is a highly sensitive tool to evaluate cell contractility within a soft extracellular matrix (ECM) environment. We propose a computational model to explore how cell-exerted contractile forces can tear up the cell-Matrigel composite material and gradually remodel it into a network structure. We identify measures that are characteristic for cellular contractility and can be obtained from image analysis of the recorded patterning process. The assay was calibrated by inhibition of NMII activity in A431 epithelial carcinoma cells either directly with blebbistatin or indirectly with Y27632 Rho kinase inhibitor. Using Matrigel patterning as a bioassay, we provide the first functional demonstration that overexpression of S100A4, a calcium-binding protein that is frequently overexpressed in metastatic tumors and inhibits NMIIA activity by inducing filament disassembly, effectively reduces cell contractility. Sensing and exerting forces is a fundamental aspect of tissue organization. We demonstrate that contractile cells form an intricate network structure when placed in a pliable culture environment, a phenomenon often associated with vascular networks and is being actively used to characterize endothelial cells in culture. We propose a computational model that operates with mechanical stresses, plastic deformation and material failure within the cell-extracellular matrix composite to explain the patterning process. In addition to re-interpret a decades-old tool of experimental cell biology, our work suggests a potentially high throughput computational assay to characterize cellular contractility within a soft ECM environment.
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Affiliation(s)
- Előd Méhes
- Department of Biological Physics, Eotvos Lorand University, Budapest, Hungary
| | - Beáta Biri-Kovács
- Department of Biochemistry, Eotvos Lorand University, Budapest, Hungary
| | - Dona G. Isai
- Department of Anatomy & Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Márton Gulyás
- Department of Biological Physics, Eotvos Lorand University, Budapest, Hungary
| | - László Nyitray
- Department of Biochemistry, Eotvos Lorand University, Budapest, Hungary
| | - András Czirók
- Department of Biological Physics, Eotvos Lorand University, Budapest, Hungary
- Department of Anatomy & Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
- * E-mail:
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16
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Marrese M, Antonovaite N, Nelemans BK, Smit TH, Iannuzzi D. Micro-indentation and optical coherence tomography for the mechanical characterization of embryos: Experimental setup and measurements on chicken embryos. Acta Biomater 2019; 97:524-534. [PMID: 31377425 DOI: 10.1016/j.actbio.2019.07.056] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/29/2019] [Accepted: 07/30/2019] [Indexed: 10/26/2022]
Abstract
The investigation of the mechanical properties of embryos is expected to provide valuable information on the phenomenology of morphogenesis. It is thus believed that, by mapping the viscoelastic features of an embryo at different stages of growth, it may be possible to shed light on the role of mechanics in embryonic development. To contribute to this field, we present a new instrument that can determine spatiotemporal distributions of mechanical properties of embryos over a wide area and with unprecedented accuracy. The method relies on combining ferrule-top micro-indentation, which provides local measurements of viscoelasticity, with Optical Coherence Tomography, which can reveal changes in tissue morphology and help the user identify the indentation point. To prove the working principle, we have collected viscoelasticity maps of fixed and live HH11-HH12 chicken embryos. Our study shows that the instrument can reveal correlations between tissue morphology and mechanical behavior. STATEMENT OF SIGNIFICANCE: Local mechanical properties of soft biological tissue play a crucial role in several biological processes, including cell differentiation, cell migration, and body formation; therefore, measuring tissue properties at high resolution is of great interest in biology and tissue engineering. To provide an efficient method for the biomechanical characterization of soft biological tissues, we introduce a new tool in which the combination of non-invasive Optical Coherence Tomography imaging and depth-controlled indentation measurements allows one to map the viscoelastic properties of biological tissue and investigate correlations between local mechanical features and tissue morphology with unprecedented resolution.
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17
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Koyama H, Shi D, Fujimori T. Biophysics in oviduct: Planar cell polarity, cilia, epithelial fold and tube morphogenesis, egg dynamics. Biophys Physicobiol 2019; 16:89-107. [PMID: 30923666 PMCID: PMC6435019 DOI: 10.2142/biophysico.16.0_89] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/29/2019] [Indexed: 12/14/2022] Open
Abstract
Organs and tissues in multi-cellular organisms exhibit various morphologies. Tubular organs have multi-scale morphological features which are closely related to their functions. Here we discuss morphogenesis and the mechanical functions of the vertebrate oviduct in the female reproductive tract, also known as the fallopian tube. The oviduct functions to convey eggs from the ovary to the uterus. In the luminal side of the oviduct, the epithelium forms multiple folds (or ridges) well-aligned along the longitudinal direction of the tube. In the epithelial cells, cilia are formed orienting toward the downstream of the oviduct. The cilia and the folds are supposed to be involved in egg transportation. Planar cell polarity (PCP) is developed in the epithelium, and the disruption of the Celsr1 gene, a PCP related-gene, causes randomization of both cilia and fold orientations, discontinuity of the tube, inefficient egg transportation, and infertility. In this review article, we briefly introduce various biophysical and biomechanical issues in the oviduct, including physical mechanisms of formation of PCP and organized cilia orientation, epithelial cell shape regulation, fold pattern formation generated by mechanical buckling, tubulogenesis, and egg transportation regulated by fluid flow. We also mention about possible roles of the oviducts in egg shape formation and embryogenesis, sinuous patterns of tubes, and fold and tube patterns observed in other tubular organs such as the gut, airways, etc.
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Affiliation(s)
- Hiroshi Koyama
- Division of Embryology, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
| | - Dongbo Shi
- Division of Embryology, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
- Centre for Organismal Studies, Heidelberg University, Heidelberg 69120, Germany
| | - Toshihiko Fujimori
- Division of Embryology, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
- CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
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18
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Khairy K, Lemon W, Amat F, Keller PJ. A Preferred Curvature-Based Continuum Mechanics Framework for Modeling Embryogenesis. Biophys J 2019; 114:267-277. [PMID: 29401426 DOI: 10.1016/j.bpj.2017.11.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 11/12/2017] [Accepted: 11/14/2017] [Indexed: 12/20/2022] Open
Abstract
Mechanics plays a key role in the development of higher organisms. However, understanding this relationship is complicated by the difficulty of modeling the link between local forces generated at the subcellular level and deformations observed at the tissue and whole-embryo levels. Here we propose an approach first developed for lipid bilayers and cell membranes, in which force-generation by cytoskeletal elements enters a continuum mechanics formulation for the full system in the form of local changes in preferred curvature. This allows us to express and solve the system using only tissue strains. Locations of preferred curvature are simply related to products of gene expression. A solution, in that context, means relaxing the system's mechanical energy to yield global morphogenetic predictions that accommodate a tendency toward the local preferred curvature, without a need to explicitly model force-generation mechanisms at the molecular level. Our computational framework, which we call SPHARM-MECH, extends a 3D spherical harmonics parameterization known as SPHARM to combine this level of abstraction with a sparse shape representation. The integration of these two principles allows computer simulations to be performed in three dimensions on highly complex shapes, gene expression patterns, and mechanical constraints. We demonstrate our approach by modeling mesoderm invagination in the fruit-fly embryo, where local forces generated by the acto-myosin meshwork in the region of the future mesoderm lead to formation of a ventral tissue fold. The process is accompanied by substantial changes in cell shape and long-range cell movements. Applying SPHARM-MECH to whole-embryo live imaging data acquired with light-sheet microscopy reveals significant correlation between calculated and observed tissue movements. Our analysis predicts the observed cell shape anisotropy on the ventral side of the embryo and suggests an active mechanical role of mesoderm invagination in supporting the onset of germ-band extension.
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19
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Nerurkar NL, Lee C, Mahadevan L, Tabin CJ. Molecular control of macroscopic forces drives formation of the vertebrate hindgut. Nature 2019; 565:480-484. [PMID: 30651642 PMCID: PMC6397660 DOI: 10.1038/s41586-018-0865-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 12/06/2018] [Indexed: 01/23/2023]
Affiliation(s)
- Nandan L Nerurkar
- Department of Genetics, Harvard Medical School, Boston, MA, USA. .,Department of Biomedical Engineering, Columbia University, New York, NY, USA. .,Department of Genetics and Development, Columbia University Medical Center, New York, NY, USA.
| | - ChangHee Lee
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - L Mahadevan
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.,Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.,Department of Physics, Harvard University, Cambridge, MA, USA.,Kavli Institute for Bionano Science and Technology, Harvard University, Cambridge, MA, USA
| | - Clifford J Tabin
- Department of Genetics, Harvard Medical School, Boston, MA, USA.
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20
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Erdemci-Tandogan G, Clark MJ, Amack JD, Manning ML. Tissue Flow Induces Cell Shape Changes During Organogenesis. Biophys J 2018; 115:2259-2270. [PMID: 30455043 PMCID: PMC6289824 DOI: 10.1016/j.bpj.2018.10.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/03/2018] [Accepted: 10/24/2018] [Indexed: 12/11/2022] Open
Abstract
In embryonic development, cell shape changes are essential for building functional organs, but in many cases, the mechanisms that precisely regulate these changes remain unknown. We propose that fluid-like drag forces generated by the motion of an organ through surrounding tissue could generate changes to its structure that are important for its function. To test this hypothesis, we study the zebrafish left-right organizer, Kupffer's vesicle (KV), using experiments and mathematical modeling. During development, monociliated cells that comprise KV undergo region-specific shape changes along the anterior-posterior axis that are critical for KV function: anterior cells become long and thin, whereas posterior cells become short and squat. Here, we develop a mathematical vertex-like model for cell shapes that incorporates both tissue rheology and cell motility and constrain the model parameters using previously published rheological data for the zebrafish tailbud as well as our own measurements of the KV speed. We find that drag forces due to dynamics of cells surrounding KV could be sufficient or work in concert with previously identified mechanisms to drive KV cell shape changes during KV development. More broadly, these results suggest that cell shape changes during embryonic development and beyond could be driven by dynamic forces not typically considered in models or experiments.
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Affiliation(s)
| | - Madeline J Clark
- Department of Cell and Developmental Biology, State University of New York, Upstate Medical University, Syracuse, New York
| | - Jeffrey D Amack
- Department of Cell and Developmental Biology, State University of New York, Upstate Medical University, Syracuse, New York
| | - M Lisa Manning
- Department of Physics, Syracuse University, Syracuse, New York
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21
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Koyama H, Fujimori T. Biomechanics of epithelial fold pattern formation in the mouse female reproductive tract. Curr Opin Genet Dev 2018; 51:59-66. [DOI: 10.1016/j.gde.2018.06.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 05/07/2018] [Accepted: 06/19/2018] [Indexed: 12/14/2022]
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22
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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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23
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Oltean A, Taber LA. Apoptosis generates mechanical forces that close the lens vesicle in the chick embryo. Phys Biol 2018; 15:025001. [PMID: 28914615 DOI: 10.1088/1478-3975/aa8d0e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
During the initial stages of eye development, optic vesicles grow laterally outward from both sides of the forebrain and come into contact with the surrounding surface ectoderm (SE). Within the region of contact, these layers then thicken locally to create placodes and invaginate to form the optic cup (primitive retina) and lens vesicle (LV), respectively. This paper examines the biophysical mechanisms involved in LV formation, which consists of three phases: (1) lens placode formation; (2) invagination to create the lens pit (LP); and (3) closure to form a complete ellipsoidally shaped LV. Previous studies have suggested that extracellular matrix deposited between the SE and optic vesicle causes the lens placode to form by locally constraining expansion of the SE as it grows, while actomyosin contraction causes this structure to invaginate. Here, using computational modeling and experiments on chick embryos, we confirm that these mechanisms for Phases 1 and 2 are physically plausible. Our results also suggest, however, that they are not sufficient to close the LP during Phase 3. We postulate that apoptosis provides an additional mechanism by removing cells near the LP opening, thereby decreasing its circumference and generating tension that closes the LP. This hypothesis is supported by staining that shows a ring of cell death located around the LP opening during closure. Inhibiting apoptosis in cultured embryos using caspase inhibitors significantly reduced LP closure, and results from a finite-element model indicate that closure driven by cell death is plausible. Taken together, our results suggest an important mechanical role for apoptosis in lens development.
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Affiliation(s)
- Alina Oltean
- Department of Biomedical Engineering, Washington University, St Louis, MO 63130, United States of America
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24
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Nelson CM, Gleghorn JP, Pang MF, Jaslove JM, Goodwin K, Varner VD, Miller E, Radisky DC, Stone HA. Microfluidic chest cavities reveal that transmural pressure controls the rate of lung development. Development 2017; 144:4328-4335. [PMID: 29084801 DOI: 10.1242/dev.154823] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 10/24/2017] [Indexed: 12/30/2022]
Abstract
Mechanical forces are increasingly recognized to regulate morphogenesis, but how this is accomplished in the context of the multiple tissue types present within a developing organ remains unclear. Here, we use bioengineered 'microfluidic chest cavities' to precisely control the mechanical environment of the fetal lung. We show that transmural pressure controls airway branching morphogenesis, the frequency of airway smooth muscle contraction, and the rate of developmental maturation of the lungs, as assessed by transcriptional analyses. Time-lapse imaging reveals that branching events are synchronized across distant locations within the lung, and are preceded by long-duration waves of airway smooth muscle contraction. Higher transmural pressure decreases the interval between systemic smooth muscle contractions and increases the rate of morphogenesis of the airway epithelium. These data reveal that the mechanical properties of the microenvironment instruct crosstalk between different tissues to control the development of the embryonic lung.
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Affiliation(s)
- Celeste M Nelson
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, USA .,Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Jason P Gleghorn
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Mei-Fong Pang
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Jacob M Jaslove
- Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Katharine Goodwin
- Quantitative and Computational Biology, Princeton University, Princeton, NJ 08544, USA
| | - Victor D Varner
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Erin Miller
- Department of Cancer Biology, Mayo Clinic Cancer Center, Jacksonville, FL 32224, USA
| | - Derek C Radisky
- Department of Cancer Biology, Mayo Clinic Cancer Center, Jacksonville, FL 32224, USA
| | - Howard A Stone
- Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA
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25
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Koyama H, Shi D, Suzuki M, Ueno N, Uemura T, Fujimori T. Mechanical Regulation of Three-Dimensional Epithelial Fold Pattern Formation in the Mouse Oviduct. Biophys J 2017; 111:650-665. [PMID: 27508448 DOI: 10.1016/j.bpj.2016.06.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 06/06/2016] [Accepted: 06/28/2016] [Indexed: 11/29/2022] Open
Abstract
Epithelia exhibit various three-dimensional morphologies linked to organ function in animals. However, the mechanisms of three-dimensional morphogenesis remain elusive. The luminal epithelium of the mouse oviduct forms well-aligned straight folds along the longitudinal direction of the tubes. Disruption of the Celsr1 gene, a planar cell polarity-related gene, causes ectopically branched folds. Here, we evaluated the mechanical contributions of the epithelium to the fold pattern formation. In the mutant oviduct, the epithelium was more intricate along the longitudinal direction than in the wild-type, suggesting a higher ratio of the longitudinal length of the epithelial layer to that of the surrounding smooth muscle (SM) layer (L-Epi/SM ratio). Our mathematical modeling and computational simulations suggested that the L-Epi/SM ratio could explain the differences in fold branching between the two genotypes. Longitudinal epithelial tensions were increased in well-aligned folds compared with those in disorganized folds both in the simulations and in experimental estimations. Artificially increasing the epithelial tensions suppressed the branching in simulations, suggesting that the epithelial tensions can regulate fold patterning. The epithelial tensions could be explained by the combination of line tensions along the epithelial cell-cell boundaries with the polarized cell arrays observed in vivo. These results suggest that the fold pattern is associated with the polarized cell array through the longitudinal epithelial tension. Further simulations indicated that the L-Epi/SM ratio could contribute to fold pattern diversity, suggesting that the L-Epi/SM ratio is a critical parameter in the fold patterning in tubular organs.
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Affiliation(s)
- Hiroshi Koyama
- Division of Embryology, National Institute for Basic Biology, Okazaki, Aichi, Japan; SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa, Japan.
| | - Dongbo Shi
- Division of Embryology, National Institute for Basic Biology, Okazaki, Aichi, Japan; Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Makoto Suzuki
- SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa, Japan; Division of Morphogenesis, National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Naoto Ueno
- SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa, Japan; Division of Morphogenesis, National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Tadashi Uemura
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Toshihiko Fujimori
- Division of Embryology, National Institute for Basic Biology, Okazaki, Aichi, Japan; SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan.
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26
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Hosseini HS, Garcia KE, Taber LA. A new hypothesis for foregut and heart tube formation based on differential growth and actomyosin contraction. Development 2017; 144:2381-2391. [PMID: 28526751 DOI: 10.1242/dev.145193] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 05/10/2017] [Indexed: 01/14/2023]
Abstract
For decades, it was commonly thought that the bilateral heart fields in the early embryo fold directly towards the midline, where they meet and fuse to create the primitive heart tube. Recent studies have challenged this view, however, suggesting that the heart fields fold diagonally. As early foregut and heart tube morphogenesis are intimately related, this finding also raises questions concerning the traditional view of foregut formation. Here, we combine experiments on chick embryos with computational modeling to explore a new hypothesis for the physical mechanisms of heart tube and foregut formation. According to our hypothesis, differential anisotropic growth between mesoderm and endoderm drives diagonal folding. Then, active contraction along the anterior intestinal portal generates tension to elongate the foregut and heart tube. We test this hypothesis using biochemical perturbations of cell proliferation and contractility, as well as computational modeling based on nonlinear elasticity theory including growth and contraction. The present results generally support the view that differential growth and actomyosin contraction drive formation of the foregut and heart tube in the early chick embryo.
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Affiliation(s)
- Hadi S Hosseini
- Department of Biomedical Engineering, Washington University, St Louis, MO 63130, USA.,Department of Physics, Washington University, St Louis, MO 63130, USA
| | - Kara E Garcia
- Department of Biomedical Engineering, Washington University, St Louis, MO 63130, USA
| | - Larry A Taber
- Department of Biomedical Engineering, Washington University, St Louis, MO 63130, USA
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27
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Davidson LA. Mechanical design in embryos: mechanical signalling, robustness and developmental defects. Philos Trans R Soc Lond B Biol Sci 2017; 372:20150516. [PMID: 28348252 PMCID: PMC5379024 DOI: 10.1098/rstb.2015.0516] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2016] [Indexed: 12/18/2022] Open
Abstract
Embryos are shaped by the precise application of force against the resistant structures of multicellular tissues. Forces may be generated, guided and resisted by cells, extracellular matrix, interstitial fluids, and how they are organized and bound within the tissue's architecture. In this review, we summarize our current thoughts on the multiple roles of mechanics in direct shaping, mechanical signalling and robustness of development. Genetic programmes of development interact with environmental cues to direct the composition of the early embryo and endow cells with active force production. Biophysical advances now provide experimental tools to measure mechanical resistance and collective forces during morphogenesis and are allowing integration of this field with studies of signalling and patterning during development. We focus this review on concepts that highlight this integration, and how the unique contributions of mechanical cues and gradients might be tested side by side with conventional signalling systems. We conclude with speculation on the integration of large-scale programmes of development, and how mechanical responses may ensure robust development and serve as constraints on programmes of tissue self-assembly.This article is part of the themed issue 'Systems morphodynamics: understanding the development of tissue hardware'.
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Affiliation(s)
- Lance A Davidson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
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Chanet S, Miller CJ, Vaishnav ED, Ermentrout B, Davidson LA, Martin AC. Actomyosin meshwork mechanosensing enables tissue shape to orient cell force. Nat Commun 2017; 8:15014. [PMID: 28504247 PMCID: PMC5440693 DOI: 10.1038/ncomms15014] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 02/17/2017] [Indexed: 12/23/2022] Open
Abstract
Sculpting organism shape requires that cells produce forces with proper directionality. Thus, it is critical to understand how cells orient the cytoskeleton to produce forces that deform tissues. During Drosophila gastrulation, actomyosin contraction in ventral cells generates a long, narrow epithelial furrow, termed the ventral furrow, in which actomyosin fibres and tension are directed along the length of the furrow. Using a combination of genetic and mechanical perturbations that alter tissue shape, we demonstrate that geometrical and mechanical constraints act as cues to orient the cytoskeleton and tension during ventral furrow formation. We developed an in silico model of two-dimensional actomyosin meshwork contraction, demonstrating that actomyosin meshworks exhibit an inherent force orienting mechanism in response to mechanical constraints. Together, our in vivo and in silico data provide a framework for understanding how cells orient force generation, establishing a role for geometrical and mechanical patterning of force production in tissues. Large-scale tissue reorganization requires the generation of directional tension, which requires orientation of the cytoskeleton. Here Chanet et al. alter tissue shape and tension in the Drosophila embryo to show that geometric and mechanical constraints act as cues to orient the cytoskeleton and tension.
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Affiliation(s)
- Soline Chanet
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Callie J Miller
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Eeshit Dhaval Vaishnav
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Bard Ermentrout
- Department of Mathematics, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Lance A Davidson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.,Department of Developmental Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.,Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
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29
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Sydow HG, Pieper T, Viebahn C, Tsikolia N. An Early Chick Embryo Culture Device for Extended Continuous Observation. Methods Mol Biol 2017; 1650:309-317. [PMID: 28809031 DOI: 10.1007/978-1-4939-7216-6_21] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Appropriate mechanical tension of the vitelline membrane as the culture substrate for the early chick embryo is frequently reported to be required for successful in vitro development. Here we describe a modified device, made of anodized aluminum, for in vitro culture which we used for studies of left-right symmetry breaking with emphasis on morphology and gene expression as readouts. The technique allows for easy, high-throughput tissue handling and provides a suitable tension in a stable and easily reproducible manner proven to be suitable for correct molecular left-right patterning and heart looping after long-term culture.
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Affiliation(s)
- Hans-Georg Sydow
- Anatomy and Embryology, University Medical Centre, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Tobias Pieper
- Anatomy and Embryology, University Medical Centre, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Christoph Viebahn
- Anatomy and Embryology, University Medical Centre, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Nikoloz Tsikolia
- Anatomy and Embryology, University Medical Centre, Kreuzbergring 36, 37075, Göttingen, Germany.
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30
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Fleury V, Murukutla AV, Chevalier NR, Gallois B, Capellazzi-Resta M, Picquet P, Peaucelle A. Physics of amniote formation. Phys Rev E 2016; 94:022426. [PMID: 27627351 DOI: 10.1103/physreve.94.022426] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Indexed: 11/07/2022]
Abstract
We present a detailed study of the formation of the amniotic sac in the avian embryo, and a comparison with the crocodile amniotic sac. We show that the amniotic sac forms at a circular line of stiffness contrast, separating rings of cell domains. Cells align at this boundary, and this in turn orients and concentrates the tension forces. The tissue fold which forms the amniotic sac is locked exactly along this line due to the colocalization of the stiffness contrast and of the tensile force. In addition, the tensile force plays a regenerative role when the amniotic sac is cut. The fold forming the ventral side of the embryo displays the same characteristics. This work shows that amniote embryogenesis consists of a cascade of buckling events taking place at the boundaries between regions of differing mechanical properties. Hence, amniote embryogenesis relies on a simple and robust biomechanical scheme used repeatedly, and selected ancestrally.
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Affiliation(s)
- Vincent Fleury
- Laboratoire Matière et Systèmes Complexes, UMR 7057, Université Paris Diderot/CNRS, 10 rue Alice Domont et Léonie Duquet, Paris 75013, France
| | - Ameya Vaishnavi Murukutla
- Laboratoire Matière et Systèmes Complexes, UMR 7057, Université Paris Diderot/CNRS, 10 rue Alice Domont et Léonie Duquet, Paris 75013, France
| | - Nicolas R Chevalier
- Laboratoire Matière et Systèmes Complexes, UMR 7057, Université Paris Diderot/CNRS, 10 rue Alice Domont et Léonie Duquet, Paris 75013, France
| | - Benjamin Gallois
- Laboratoire Matière et Systèmes Complexes, UMR 7057, Université Paris Diderot/CNRS, 10 rue Alice Domont et Léonie Duquet, Paris 75013, France
| | - Marina Capellazzi-Resta
- Laboratoire Matière et Systèmes Complexes, UMR 7057, Université Paris Diderot/CNRS, 10 rue Alice Domont et Léonie Duquet, Paris 75013, France
| | - Pierre Picquet
- Alligator Bay, 62 route du Mont Saint-Michel, Beauvoir 50170, Manche, France
| | - Alexis Peaucelle
- Laboratoire Matière et Systèmes Complexes, UMR 7057, Université Paris Diderot/CNRS, 10 rue Alice Domont et Léonie Duquet, Paris 75013, France
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31
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Wide and high resolution tension measurement using FRET in embryo. Sci Rep 2016; 6:28535. [PMID: 27335157 PMCID: PMC4917836 DOI: 10.1038/srep28535] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 06/03/2016] [Indexed: 11/08/2022] Open
Abstract
During embryonic development, physical force plays an important role in morphogenesis and differentiation. Stretch sensitive fluorescence resonance energy transfer (FRET) has the potential to provide non-invasive tension measurements inside living tissue. In this study, we introduced a FRET-based actinin tension sensor into Xenopus laevis embryos and demonstrated that this sensor captures variation of tension across differentiating ectoderm. The actinin tension sensor, containing mCherry and EGFP connected by spider silk protein, was validated in human embryonic kidney (HEK) cells and embryos. It co-localized with actin filaments and changed FRET efficiencies in response to actin filament destruction, myosin deactivation, and osmotic perturbation. Time-lapse FRET analysis showed that the prospective neural ectoderm bears higher tension than the epidermal ectoderm during gastrulation and neurulation, and cells morphogenetic behavior correlated with the tension difference. These data confirmed that the sensor enables us to measure tension across tissues concurrently and with high resolution.
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32
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Siedlik MJ, Varner VD, Nelson CM. Pushing, pulling, and squeezing our way to understanding mechanotransduction. Methods 2016; 94:4-12. [PMID: 26318086 PMCID: PMC4761538 DOI: 10.1016/j.ymeth.2015.08.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 07/23/2015] [Accepted: 08/25/2015] [Indexed: 01/28/2023] Open
Abstract
Mechanotransduction is often described in the context of force-induced changes in molecular conformation, but molecular-scale mechanical stimuli arise in vivo in the context of complex, multicellular tissue structures. For this reason, we highlight and review experimental methods for investigating mechanotransduction across multiple length scales. We begin by discussing techniques that probe the response of individual molecules to applied force. We then move up in length scale to highlight techniques aimed at uncovering how cells transduce mechanical stimuli into biochemical activity. Finally, we discuss approaches for determining how these stimuli arise in multicellular structures. We expect that future work will combine techniques across these length scales to provide a more comprehensive understanding of mechanotransduction.
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Affiliation(s)
- Michael J Siedlik
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, United States
| | - Victor D Varner
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, United States
| | - Celeste M Nelson
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, United States; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, United States.
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33
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Perrone MC, Veldhuis JH, Brodland GW. Non-straight cell edges are important to invasion and engulfment as demonstrated by cell mechanics model. Biomech Model Mechanobiol 2015; 15:405-18. [PMID: 26148533 PMCID: PMC4792343 DOI: 10.1007/s10237-015-0697-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 06/23/2015] [Indexed: 11/28/2022]
Abstract
Computational models of cell–cell mechanical interactions typically simulate sorting and certain other motions well, but as demands on these models continue to grow, discrepancies between the cell shapes, contact angles and behaviours they predict and those that occur in real cells have come under increased scrutiny. To investigate whether these discrepancies are a direct result of the straight cell–cell edges generally assumed in these models, we developed a finite element model that approximates cell boundaries using polylines with an arbitrary number of segments. We then compared the predictions of otherwise identical polyline and monoline (straight-edge) models in a variety of scenarios, including annealing, single- and multi-cell engulfment, sorting, and two forms of mixing—invasion and checkerboard pattern formation. Keeping cell–cell edges straight influences cell motion, cell shape, contact angle, and boundary length, especially in cases where one cell type is pulled between or around cells of a different type, as in engulfment or invasion. These differences arise because monoline cells have restricted deformation modes. Polyline cells do not face these restrictions, and with as few as three segments per edge yielded realistic edge shapes and contact angle errors one-tenth of those produced by monoline models, making them considerably more suitable for situations where angles and shapes matter, such as validation of cellular force–inference techniques. The findings suggest that non-straight cell edges are important both in modelling and in nature.
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Affiliation(s)
- Matthew C Perrone
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Jim H Veldhuis
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - G Wayne Brodland
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
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34
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Barbier de Reuille P, Routier-Kierzkowska AL, Kierzkowski D, Bassel GW, Schüpbach T, Tauriello G, Bajpai N, Strauss S, Weber A, Kiss A, Burian A, Hofhuis H, Sapala A, Lipowczan M, Heimlicher MB, Robinson S, Bayer EM, Basler K, Koumoutsakos P, Roeder AHK, Aegerter-Wilmsen T, Nakayama N, Tsiantis M, Hay A, Kwiatkowska D, Xenarios I, Kuhlemeier C, Smith RS. MorphoGraphX: A platform for quantifying morphogenesis in 4D. eLife 2015; 4:05864. [PMID: 25946108 PMCID: PMC4421794 DOI: 10.7554/elife.05864] [Citation(s) in RCA: 303] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 04/03/2015] [Indexed: 12/25/2022] Open
Abstract
Morphogenesis emerges from complex multiscale interactions between genetic and mechanical processes. To understand these processes, the evolution of cell shape, proliferation and gene expression must be quantified. This quantification is usually performed either in full 3D, which is computationally expensive and technically challenging, or on 2D planar projections, which introduces geometrical artifacts on highly curved organs. Here we present MorphoGraphX ( www.MorphoGraphX.org), a software that bridges this gap by working directly with curved surface images extracted from 3D data. In addition to traditional 3D image analysis, we have developed algorithms to operate on curved surfaces, such as cell segmentation, lineage tracking and fluorescence signal quantification. The software's modular design makes it easy to include existing libraries, or to implement new algorithms. Cell geometries extracted with MorphoGraphX can be exported and used as templates for simulation models, providing a powerful platform to investigate the interactions between shape, genes and growth.
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Affiliation(s)
| | - Anne-Lise Routier-Kierzkowska
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Daniel Kierzkowski
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - George W Bassel
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | | | | | - Namrata Bajpai
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Sören Strauss
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Alain Weber
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Annamaria Kiss
- Reproduction et Développement des Plantes, Ecole Normale Supérieure de Lyon, Lyon, France
- Laboratoire Joliot Curie, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Agata Burian
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
- Department of Biophysics and Morphogenesis of Plants, University of Silesia, Katowice, Poland
| | - Hugo Hofhuis
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Aleksandra Sapala
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Marcin Lipowczan
- Department of Biophysics and Morphogenesis of Plants, University of Silesia, Katowice, Poland
| | | | - Sarah Robinson
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Emmanuelle M Bayer
- Laboratory of Membrane Biogenesis, University of Bordeaux, Bordeaux, France
| | - Konrad Basler
- Institute of Molecular Life Sciences, Zurich, Switzerland
| | | | - Adrienne HK Roeder
- Weill Institute for Cell and Molecular Biology and School of Integrative Plant Science, Section of Plant Biology, Cornell University, Ithaca, United States
| | | | - Naomi Nakayama
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
- Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Miltos Tsiantis
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Angela Hay
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Dorota Kwiatkowska
- Department of Biophysics and Morphogenesis of Plants, University of Silesia, Katowice, Poland
| | | | - Cris Kuhlemeier
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Richard S Smith
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
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35
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Aleksandrova A, Czirok A, Kosa E, Galkin O, Cheuvront TJ, Rongish BJ. The endoderm and myocardium join forces to drive early heart tube assembly. Dev Biol 2015; 404:40-54. [PMID: 25952622 DOI: 10.1016/j.ydbio.2015.04.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/17/2015] [Accepted: 04/21/2015] [Indexed: 11/30/2022]
Abstract
Formation of the muscular layer of the heart, the myocardium, involves the medial movement of bilateral progenitor fields; driven primarily by shortening of the endoderm during foregut formation. Using a combination of time-lapse imaging, microsurgical perturbations and computational modeling, we show that the speed of the medial-ward movement of the myocardial progenitors is similar, but not identical to that of the adjacent endoderm. Further, the extracellular matrix microenvironment separating the two germ layers also moves with the myocardium, indicating that collective tissue motion and not cell migration drives tubular heart assembly. Importantly, as myocardial cells approach the midline, they perform distinct anterior-directed movements relative to the endoderm. Based on the analysis of microincision experiments and computational models, we propose two characteristic, autonomous morphogenetic activities within the early myocardium: 1) an active contraction of the medial portion of the heart field and 2) curling- the tendency of the unconstrained myocardial tissue to form a spherical surface with a concave ventral side. In the intact embryo, these deformations are constrained by the endoderm and the adjacent mesoderm, nevertheless the corresponding mechanical stresses contribute to the proper positioning of myocardial primordia.
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Affiliation(s)
- Anastasiia Aleksandrova
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Andras Czirok
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA; Department of Biological Physics, Eotvos University, Budapest, Hungary
| | - Edina Kosa
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Oleksandr Galkin
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Tracey J Cheuvront
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Brenda J Rongish
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
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36
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37
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Feroze R, Shawky JH, von Dassow M, Davidson LA. Mechanics of blastopore closure during amphibian gastrulation. Dev Biol 2015; 398:57-67. [PMID: 25448691 PMCID: PMC4317491 DOI: 10.1016/j.ydbio.2014.11.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 11/04/2014] [Accepted: 11/11/2014] [Indexed: 11/16/2022]
Abstract
Blastopore closure in the amphibian embryo involves large scale tissue reorganization driven by physical forces. These forces are tuned to generate sustained blastopore closure throughout the course of gastrulation. We describe the mechanics of blastopore closure at multiple scales and in different regions around the blastopore by characterizing large scale tissue deformations, cell level shape change and subcellular F-actin organization and by measuring tissue force production and structural stiffness of the blastopore during gastrulation. We find that the embryo generates a ramping magnitude of force until it reaches a peak force on the order of 0.5μN. During this time course, the embryo also stiffens 1.5 fold. Strain rate mapping of the dorsal, ventral and lateral epithelial cells proximal to the blastopore reveals changing patterns of strain rate throughout closure. Cells dorsal to the blastopore, which are fated to become neural plate ectoderm, are polarized and have straight boundaries. In contrast, cells lateral and ventral to the blastopore are less polarized and have tortuous cell boundaries. The F-actin network is organized differently in each region with the highest percentage of alignment occurring in the lateral region. Interestingly F-actin was consistently oriented toward the blastopore lip in dorsal and lateral cells, but oriented parallel to the lip in ventral regions. Cell shape and F-actin alignment analyses reveal different local mechanical environments in regions around the blastopore, which was reflected by the strain rate maps.
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Affiliation(s)
- Rafey Feroze
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; School of Medicine, University of Pittsburgh Medical Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Joseph H Shawky
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michelangelo von Dassow
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Duke University Marine Lab, Beaufort, NC 28516, USA
| | - Lance A Davidson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA, USA.
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38
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Alford PW. Elasticity-based targeted growth models of morphogenesis. Methods Mol Biol 2015; 1189:339-350. [PMID: 25245704 DOI: 10.1007/978-1-4939-1164-6_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Embryonic tissue mechanics play an important role in regulating morphogenesis during organ formation, both in a bottom-up sense, where changes in gene expression drive mechanical shape changes, and in a top-down sense, where perturbations in tissue mechanics feed back to drive changes in gene expression. In growing tissues that can generate internal forces and have complex geometries, like those in the embryo, it can often be difficult to empirically determine the mechanical state of the tissue, let alone the relationships between gene expression and mechanical behavior. Mathematical models can be used to fill this gap. Here, we discuss elasticity-based models for growing tissues with a specific focus on targeted growth in embryonic tissues.
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Affiliation(s)
- Patrick W Alford
- Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street, SE 7-105 Nils Hasselmo Hall, Minneapolis, MN, 55455, USA,
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39
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Czirok A, Isai DG. Cell resolved, multiparticle model of plastic tissue deformations and morphogenesis. Phys Biol 2014; 12:016005. [PMID: 25502910 DOI: 10.1088/1478-3975/12/1/016005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We propose a three-dimensional mechanical model of embryonic tissue dynamics. Mechanically coupled adherent cells are represented as particles interconnected with elastic beams which can exert non-central forces and torques. Tissue plasticity is modeled by a stochastic process consisting of a connectivity change (addition or removal of a single link) followed by a complete relaxation to mechanical equilibrium. In particular, we assume that (i) two non-connected, but adjacent particles can form a new link; and (ii) the lifetime of links is reduced by tensile forces. We demonstrate that the proposed model yields a realistic macroscopic elasto-plastic behavior and we establish how microscopic model parameters determine material properties at the macroscopic scale. Based on these results, microscopic parameter values can be inferred from tissue thickness, macroscopic elastic modulus and the magnitude and dynamics of intercellular adhesion forces. In addition to their mechanical role, model particles can also act as simulation agents and actively modulate their connectivity according to specific rules. As an example, anisotropic link insertion and removal probabilities can give rise to local cell intercalation and large scale convergent extension movements. The proposed stochastic simulation of cell activities yields fluctuating tissue movements which exhibit the same autocorrelation properties as empirical data from avian embryos.
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Affiliation(s)
- Andras Czirok
- Department of Anatomy & Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA. Department of Biological Physics, Eotvos University, Budapest, Hungary
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40
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Abstract
Branching morphogenesis is the developmental program that builds the ramified epithelial trees of various organs, including the airways of the lung, the collecting ducts of the kidney, and the ducts of the mammary and salivary glands. Even though the final geometries of epithelial trees are distinct, the molecular signaling pathways that control branching morphogenesis appear to be conserved across organs and species. However, despite this molecular homology, recent advances in cell lineage analysis and real-time imaging have uncovered surprising differences in the mechanisms that build these diverse tissues. Here, we review these studies and discuss the cellular and physical mechanisms that can contribute to branching morphogenesis.
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Affiliation(s)
- Victor D Varner
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Celeste M Nelson
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, USA Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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41
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Manning AJ, Rogers SL. The Fog signaling pathway: insights into signaling in morphogenesis. Dev Biol 2014; 394:6-14. [PMID: 25127992 PMCID: PMC4182926 DOI: 10.1016/j.ydbio.2014.08.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 07/28/2014] [Accepted: 08/04/2014] [Indexed: 12/28/2022]
Abstract
Epithelia form the building blocks of many tissue and organ types. Epithelial cells often form a contiguous 2-dimensional sheet that is held together by strong adhesions. The mechanical properties conferred by these adhesions allow the cells to undergo dramatic three-dimensional morphogenetic movements while maintaining cell–cell contacts during embryogenesis and post-embryonic development. The Drosophila Folded gastrulation pathway triggers epithelial cell shape changes that drive gastrulation and tissue folding and is one of the most extensively studied examples of epithelial morphogenesis. This pathway has yielded key insights into the signaling mechanisms and cellular machinery involved in epithelial remodeling. In this review, we discuss principles of morphogenesis and signaling that have been discovered through genetic and cell biological examination of this pathway. We also consider various regulatory mechanisms and the system's relevance to mammalian development. We propose future directions that will continue to broaden our knowledge of morphogenesis across taxa.
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Affiliation(s)
- Alyssa J Manning
- Department of Biochemistry, Box 357350, The University of Washington, Seattle, WA 98195-7350, USA
| | - Stephen L Rogers
- Department of Biology, The University of North Carolina at Chapel Hill, CB ♯3280, Fordham Hall, South Road, Chapel Hill, NC 27599-3280, USA; Lineberger Comprehensive Cancer Center, USA; Carolina Center for Genome Sciences, USA.
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42
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Brodland GW, Veldhuis JH, Kim S, Perrone M, Mashburn D, Hutson MS. CellFIT: a cellular force-inference toolkit using curvilinear cell boundaries. PLoS One 2014; 9:e99116. [PMID: 24921257 PMCID: PMC4055627 DOI: 10.1371/journal.pone.0099116] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 05/11/2014] [Indexed: 11/19/2022] Open
Abstract
Mechanical forces play a key role in a wide range of biological processes, from embryogenesis to cancer metastasis, and there is considerable interest in the intuitive question, "Can cellular forces be inferred from cell shapes?" Although several groups have posited affirmative answers to this stimulating question, nagging issues remained regarding equation structure, solution uniqueness and noise sensitivity. Here we show that the mechanical and mathematical factors behind these issues can be resolved by using curved cell edges rather than straight ones. We present a new package of force-inference equations and assessment tools and denote this new package CellFIT, the Cellular Force Inference Toolkit. In this approach, cells in an image are segmented and equilibrium equations are constructed for each triple junction based solely on edge tensions and the limiting angles at which edges approach each junction. The resulting system of tension equations is generally overdetermined. As a result, solutions can be obtained even when a modest number of edges need to be removed from the analysis due to short length, poor definition, image clarity or other factors. Solving these equations yields a set of relative edge tensions whose scaling must be determined from data external to the image. In cases where intracellular pressures are also of interest, Laplace equations are constructed to relate the edge tensions, curvatures and cellular pressure differences. That system is also generally overdetermined and its solution yields a set of pressures whose offset requires reference to the surrounding medium, an open wound, or information external to the image. We show that condition numbers, residual analyses and standard errors can provide confidence information about the inferred forces and pressures. Application of CellFIT to several live and fixed biological tissues reveals considerable force variability within a cell population, significant differences between populations and elevated tensions along heterotypic boundaries.
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Affiliation(s)
- G. Wayne Brodland
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
- * E-mail:
| | - Jim H. Veldhuis
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - Steven Kim
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - Matthew Perrone
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - David Mashburn
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, United States of America
| | - M. Shane Hutson
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Integrative Biosystem Research & Education, Vanderbilt University, Nashville, Tennessee, United States of America
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43
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Uriu K, Morelli LG, Oates AC. Interplay between intercellular signaling and cell movement in development. Semin Cell Dev Biol 2014; 35:66-72. [PMID: 24882723 DOI: 10.1016/j.semcdb.2014.05.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 05/15/2014] [Accepted: 05/20/2014] [Indexed: 01/30/2023]
Abstract
Cell movement and local intercellular signaling are crucial components of morphogenesis during animal development. Intercellular signaling regulates the collective movement of a cell population via direct cell-cell contact. Cell movement, conversely, can influence local intercellular signaling by rearranging neighboring cells. Here, we first discuss theoretical models that address how intercellular signaling regulates collective cell movement during development. Examples include neural crest cell migration, convergent extension, and cell movement during vertebrate axis elongation. Second, we review theoretical studies on how cell movement may affect intercellular signaling, using the segmentation clock in zebrafish as an example. We propose that interplay between cell movement and intercellular signaling must be considered when studying morphogenesis in embryonic development.
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Affiliation(s)
- Koichiro Uriu
- Theoretical Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Luis G Morelli
- Departamento de Física, FCEyN Universidad de Buenos Aires, and IFIBA, CONICET, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | - Andrew C Oates
- MRC-National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK; University College London, Gower Street, London WC1E 6BT, UK
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44
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Varner VD, Nelson CM. Let's push things forward: disruptive technologies and the mechanics of tissue assembly. Integr Biol (Camb) 2014; 5:1162-73. [PMID: 23907401 DOI: 10.1039/c3ib40080h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Although many of the molecular mechanisms that regulate tissue assembly in the embryo have been delineated, the physical forces that couple these mechanisms to actual changes in tissue form remain unclear. Qualitative studies suggest that mechanical loads play a regulatory role in development, but clear quantitative evidence has been lacking. This is partly owing to the complex nature of these problems - embryonic tissues typically undergo large deformations and exhibit evolving, highly viscoelastic material properties. Still, despite these challenges, new disruptive technologies are enabling study of the mechanics of tissue assembly in unprecedented detail. Here, we present novel experimental techniques that enable the study of each component of these physical problems: kinematics, forces, and constitutive properties. Specifically, we detail advances in light sheet microscopy, optical coherence tomography, traction force microscopy, fluorescence force spectroscopy, microrheology and micropatterning. Taken together, these technologies are helping elucidate a more quantitative understanding of the mechanics of tissue assembly.
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Affiliation(s)
- Victor D Varner
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, USA
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45
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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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46
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Wyczalkowski MA, Varner VD, Taber LA. Computational and experimental study of the mechanics of embryonic wound healing. J Mech Behav Biomed Mater 2013; 28:125-46. [PMID: 23973771 DOI: 10.1016/j.jmbbm.2013.07.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 07/14/2013] [Accepted: 07/16/2013] [Indexed: 01/07/2023]
Abstract
Wounds in the embryo show a remarkable ability to heal quickly without leaving a scar. Previous studies have found that an actomyosin ring (purse string) forms around the wound perimeter and contracts to close the wound over the course of several dozens of minutes. Here, we report experiments that reveal an even faster mechanism which remarkably closes wounds by more than 50% within the first 30s. Circular and elliptical wounds (~100μm in size) were made in the blastoderm of early chick embryos and allowed to heal, with wound area and shape characterized as functions of time. The closure rate displayed a biphasic behavior, with rapid constriction lasting about a minute, followed by a period of more gradual closure to complete healing. Fluorescent staining suggests that both healing phases are driven by actomyosin contraction, with relatively rapid contraction of fibers at cell borders within a relatively thick ring of tissue (several cells wide) around the wound followed by slower contraction of a thin supracellular actomyosin ring along the margin, consistent with a purse string mechanism. Finite-element modeling showed that this idea is biophysically plausible, with relatively isotropic contraction within the thick ring giving way to tangential contraction in the thin ring. In addition, consistent with experimental results, simulated elliptical wounds heal with little change in aspect ratio, and decreased membrane tension can cause these wounds to open briefly before going on to heal. These results provide new insight into the healing mechanism in embryonic epithelia.
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47
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Kim HY, Varner VD, Nelson CM. Apical constriction initiates new bud formation during monopodial branching of the embryonic chicken lung. Development 2013; 140:3146-55. [PMID: 23824575 DOI: 10.1242/dev.093682] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Branching morphogenesis sculpts the airway epithelium of the lung into a tree-like structure to conduct air and promote gas exchange after birth. In the avian lung, a series of buds emerges from the dorsal surface of the primary bronchus via monopodial branching to form the conducting airways; anatomically, these buds are similar to those formed by domain branching in the mammalian lung. Here, we show that monopodial branching is initiated by apical constriction of the airway epithelium, and not by differential cell proliferation, using computational modeling and quantitative imaging of embryonic chicken lung explants. Both filamentous actin and phosphorylated myosin light chain were enriched at the apical surface of the airway epithelium during monopodial branching. Consistently, inhibiting actomyosin contractility prevented apical constriction and blocked branch initiation. Although cell proliferation was enhanced along the dorsal and ventral aspects of the primary bronchus, especially before branch formation, inhibiting proliferation had no effect on the initiation of branches. To test whether the physical forces from apical constriction alone are sufficient to drive the formation of new buds, we constructed a nonlinear, three-dimensional finite element model of the airway epithelium and used it to simulate apical constriction and proliferation in the primary bronchus. Our results suggest that, consistent with the experimental results, apical constriction is sufficient to drive the early stages of monopodial branching whereas cell proliferation is dispensable. We propose that initial folding of the airway epithelium is driven primarily by apical constriction during monopodial branching of the avian lung.
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Affiliation(s)
- Hye Young Kim
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
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48
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Gleghorn JP, Manivannan S, Nelson CM. Quantitative approaches to uncover physical mechanisms of tissue morphogenesis. Curr Opin Biotechnol 2013; 24:954-61. [PMID: 23647971 DOI: 10.1016/j.copbio.2013.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 04/12/2013] [Indexed: 12/30/2022]
Abstract
Morphogenesis, the creation of tissue and organ architecture, is a series of complex and dynamic processes driven by genetic programs, microenvironmental cues, and intercellular interactions. Elucidating the physical mechanisms that generate tissue form is key to understanding development, disease, and the strategies needed for regenerative therapies. Advancements in imaging technologies, genetic recombination techniques, laser ablation, and microfabricated tissue models have enabled quantitative descriptions of the cellular motions and tissue deformations and stresses with unprecedented temporal and spatial resolution. Using these data synergistically with increasingly more sophisticated physical, mathematical, and computational models will unveil the physical mechanisms that drive morphogenesis.
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Affiliation(s)
- Jason P Gleghorn
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, United States
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Bayly PV, Taber LA, Kroenke CD. Mechanical forces in cerebral cortical folding: a review of measurements and models. J Mech Behav Biomed Mater 2013; 29:568-81. [PMID: 23566768 DOI: 10.1016/j.jmbbm.2013.02.018] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 02/17/2013] [Accepted: 02/19/2013] [Indexed: 12/22/2022]
Abstract
Folding of the cerebral cortical surface is a critical process in human brain development, yet despite decades of indirect study and speculation the mechanics of the process remain incompletely understood. Leading hypotheses have focused on the roles of circumferential expansion of the cortex, radial growth, and internal tension in neuronal fibers (axons). In this article, we review advances in the mathematical modeling of growth and morphogenesis and new experimental data, which together promise to clarify the mechanical basis of cortical folding. Recent experimental studies have illuminated not only the fundamental cellular and molecular processes underlying cortical development, but also the stress state and mechanical behavior of the developing brain. The combination of mathematical modeling and biomechanical data provides a means to evaluate hypothesized mechanisms objectively and quantitatively, and to ensure that they are consistent with physical law, given plausible assumptions and reasonable parameter values.
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Affiliation(s)
- P V Bayly
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Saint Louis, MO 63130, United States.
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50
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Filas BA, Oltean A, Majidi S, Bayly PV, Beebe DC, Taber LA. Regional differences in actomyosin contraction shape the primary vesicles in the embryonic chicken brain. Phys Biol 2012; 9:066007. [PMID: 23160445 PMCID: PMC3535267 DOI: 10.1088/1478-3975/9/6/066007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In the early embryo, the brain initially forms as a relatively straight, cylindrical epithelial tube composed of neural stem cells. The brain tube then divides into three primary vesicles (forebrain, midbrain, hindbrain), as well as a series of bulges (rhombomeres) in the hindbrain. The boundaries between these subdivisions have been well studied as regions of differential gene expression, but the morphogenetic mechanisms that generate these constrictions are not well understood. Here, we show that regional variations in actomyosin-based contractility play a major role in vesicle formation in the embryonic chicken brain. In particular, boundaries did not form in brains exposed to the nonmuscle myosin II inhibitor blebbistatin, whereas increasing contractile force using calyculin or ATP deepened boundaries considerably. Tissue staining showed that contraction likely occurs at the inner part of the wall, as F-actin and phosphorylated myosin are concentrated at the apical side. However, relatively little actin and myosin was found in rhombomere boundaries. To determine the specific physical mechanisms that drive vesicle formation, we developed a finite-element model for the brain tube. Regional apical contraction was simulated in the model, with contractile anisotropy and strength estimated from contractile protein distributions and measurements of cell shapes. The model shows that a combination of circumferential contraction in the boundary regions and relatively isotropic contraction between boundaries can generate realistic morphologies for the primary vesicles. In contrast, rhombomere formation likely involves longitudinal contraction between boundaries. Further simulations suggest that these different mechanisms are dictated by regional differences in initial morphology and the need to withstand cerebrospinal fluid pressure. This study provides a new understanding of early brain morphogenesis.
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Affiliation(s)
- Benjamen A Filas
- Department of Biomedical Engineering, Washington University, St Louis, MO 63130, USA.
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