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Wang R, Bialas AL, Goel T, Collins EMS. Mechano-Chemical Coupling in Hydra Regeneration and Patterning. Integr Comp Biol 2023; 63:1422-1441. [PMID: 37339912 DOI: 10.1093/icb/icad070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/07/2023] [Accepted: 06/12/2023] [Indexed: 06/22/2023] Open
Abstract
The freshwater cnidarian Hydra can regenerate from wounds, small tissue fragments and even from aggregated cells. This process requires the de novo development of a body axis and oral-aboral polarity, a fundamental developmental process that involves chemical patterning and mechanical shape changes. Gierer and Meinhardt recognized that Hydra's simple body plan and amenability to in vivo experiments make it an experimentally and mathematically tractable model to study developmental patterning and symmetry breaking. They developed a reaction-diffusion model, involving a short-range activator and a long-range inhibitor, which successfully explained patterning in the adult animal. In 2011, HyWnt3 was identified as a candidate for the activator. However, despite the continued efforts of both physicists and biologists, the predicted inhibitor remains elusive. Furthermore, the Gierer-Meinhardt model cannot explain de novo axis formation in cellular aggregates that lack inherited tissue polarity. The aim of this review is to synthesize the current knowledge on Hydra symmetry breaking and patterning. We summarize the history of patterning studies and insights from recent biomechanical and molecular studies, and highlight the need for continued validation of theoretical assumptions and collaboration across disciplinary boundaries. We conclude by proposing new experiments to test current mechano-chemical coupling models and suggest ideas for expanding the Gierer-Meinhardt model to explain de novo patterning, as observed in Hydra aggregates. The availability of a fully sequenced genome, transgenic fluorescent reporter strains, and modern imaging techniques, that enable unprecedented observation of cellular events in vivo, promise to allow the community to crack Hydra's secret to patterning.
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Affiliation(s)
- Rui Wang
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, 92093 CA, USA
| | - April L Bialas
- Department of Biology, Swarthmore College, 500 College Ave, Swarthmore, 19081 PA, USA
| | - Tapan Goel
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, 30332 GA, USA
- Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, 92093 CA, USA
| | - Eva-Maria S Collins
- Department of Biology, Swarthmore College, 500 College Ave, Swarthmore, 19081 PA, USA
- Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, 92093 CA, USA
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA, USA
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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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Petridou NI, Heisenberg C. Tissue rheology in embryonic organization. EMBO J 2019; 38:e102497. [PMID: 31512749 PMCID: PMC6792012 DOI: 10.15252/embj.2019102497] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/12/2019] [Accepted: 07/17/2019] [Indexed: 12/18/2022] Open
Abstract
Tissue morphogenesis in multicellular organisms is brought about by spatiotemporal coordination of mechanical and chemical signals. Extensive work on how mechanical forces together with the well-established morphogen signalling pathways can actively shape living tissues has revealed evolutionary conserved mechanochemical features of embryonic development. More recently, attention has been drawn to the description of tissue material properties and how they can influence certain morphogenetic processes. Interestingly, besides the role of tissue material properties in determining how much tissues deform in response to force application, there is increasing theoretical and experimental evidence, suggesting that tissue material properties can abruptly and drastically change in development. These changes resemble phase transitions, pointing at the intriguing possibility that important morphogenetic processes in development, such as symmetry breaking and self-organization, might be mediated by tissue phase transitions. In this review, we summarize recent findings on the regulation and role of tissue material properties in the context of the developing embryo. We posit that abrupt changes of tissue rheological properties may have important implications in maintaining the balance between robustness and adaptability during embryonic development.
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Wang R, Goel T, Khazoyan K, Sabry Z, Quan HJ, Diamond PH, Collins EMS. Mouth Function Determines the Shape Oscillation Pattern in Regenerating Hydra Tissue Spheres. Biophys J 2019; 117:1145-1155. [PMID: 31443907 DOI: 10.1016/j.bpj.2019.07.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/25/2019] [Accepted: 07/30/2019] [Indexed: 12/12/2022] Open
Abstract
Hydra is a small freshwater polyp capable of regeneration from small tissue pieces and from aggregates of cells. During regeneration, a hollow bilayered sphere is formed that undergoes osmotically driven shape oscillations of inflation and rupture. These oscillations are necessary for successful regeneration. Eventually, the oscillating sphere breaks rotational symmetry along the future head-foot axis of the animal. Notably, the shape oscillations show an abrupt shift from large-amplitude, long-period oscillations to small-amplitude, short-period oscillations. It has been widely accepted that this shift in oscillation pattern is linked to symmetry breaking and axis formation, and current theoretical models of Hydra symmetry breaking use this assumption as a model constraint. However, a mechanistic explanation for the shift in oscillation pattern is lacking. Using in vivo manipulation and imaging, we quantified the shape oscillation dynamics and dissected the timing and triggers of the pattern shift. Our experiments demonstrate that the shift in the shape oscillation pattern in regenerating Hydra tissue pieces is caused by the formation of a functional mouth and not by shape symmetry breaking as previously assumed. Thus, model assumptions must be revised in light of these new experimental data, which can be used to constrain and validate improved theoretical models of pattern formation in Hydra.
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Affiliation(s)
- Rui Wang
- Department of Bioengineering, University of California San Diego, La Jolla, California; Biology Department, Swarthmore College, Swarthmore, Pennsylvania
| | - Tapan Goel
- Department of Physics, University of California San Diego, La Jolla, California; Biology Department, Swarthmore College, Swarthmore, Pennsylvania
| | - Kate Khazoyan
- Department of Bioengineering, University of California San Diego, La Jolla, California
| | - Ziad Sabry
- Biology Department, Swarthmore College, Swarthmore, Pennsylvania
| | - Heng J Quan
- Department of Physics, University of California San Diego, La Jolla, California; Department of Mathematics, University of California San Diego, La Jolla, California
| | - Patrick H Diamond
- Department of Physics, University of California San Diego, La Jolla, California
| | - Eva-Maria S Collins
- Department of Physics, University of California San Diego, La Jolla, California; Biology Department, Swarthmore College, Swarthmore, Pennsylvania.
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Chiou K, Collins EMS. Why we need mechanics to understand animal regeneration. Dev Biol 2017; 433:155-165. [PMID: 29179947 DOI: 10.1016/j.ydbio.2017.09.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/31/2017] [Accepted: 09/17/2017] [Indexed: 12/19/2022]
Abstract
Mechanical forces are an important contributor to cell fate specification and cell migration during embryonic development in animals. Similarities between embryogenesis and regeneration, particularly with regards to pattern formation and large-scale tissue movements, suggest similarly important roles for physical forces during regeneration. While the influence of the mechanical environment on stem cell differentiation in vitro is being actively exploited in the fields of tissue engineering and regenerative medicine, comparatively little is known about the role of stresses and strains acting during animal regeneration. In this review, we summarize published work on the role of physical principles and mechanical forces in animal regeneration. Novel experimental techniques aimed at addressing the role of mechanics in embryogenesis have greatly enhanced our understanding at scales from the subcellular to the macroscopic - we believe the time is ripe for the field of regeneration to similarly leverage the tools of the mechanobiological research community.
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Affiliation(s)
- Kevin Chiou
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Eva-Maria S Collins
- Physics Department, UC San Diego, La Jolla, CA 92093, USA; Section of Cell&Developmental Biology, UC San Diego, La Jolla, CA 92093, USA.
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Mercker M, Köthe A, Marciniak-Czochra A. Mechanochemical symmetry breaking in Hydra aggregates. Biophys J 2016; 108:2396-407. [PMID: 25954896 PMCID: PMC4423050 DOI: 10.1016/j.bpj.2015.03.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 03/01/2015] [Accepted: 03/20/2015] [Indexed: 11/25/2022] Open
Abstract
Tissue morphogenesis comprises the self-organized creation of various patterns and shapes. Although detailed underlying mechanisms are still elusive in many cases, an increasing amount of experimental data suggests that chemical morphogen and mechanical processes are strongly coupled. Here, we develop and test a minimal model of the axis-defining step (i.e., symmetry breaking) in aggregates of the Hydra polyp. Based on previous findings, we combine osmotically driven shape oscillations with tissue mechanics and morphogen dynamics. We show that the model incorporating a simple feedback loop between morphogen patterning and tissue stretch reproduces a wide range of experimental data. Finally, we compare different hypothetical morphogen patterning mechanisms (Turing, tissue-curvature, and self-organized criticality). Our results suggest the experimental investigation of bigger (i.e., multiple head) aggregates as a key step for a deeper understanding of mechanochemical symmetry breaking in Hydra.
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Affiliation(s)
- Moritz Mercker
- Institute of Applied Mathematics, University of Heidelberg, Heidelberg, Germany; BioQuant, University of Heidelberg, Heidelberg, Germany; Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Heidelberg, Germany.
| | - Alexandra Köthe
- Institute of Applied Mathematics, University of Heidelberg, Heidelberg, Germany
| | - Anna Marciniak-Czochra
- Institute of Applied Mathematics, University of Heidelberg, Heidelberg, Germany; BioQuant, University of Heidelberg, Heidelberg, Germany; Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Heidelberg, Germany
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Zamparo M, Chianale F, Tebaldi C, Cosentino-Lagomarsino M, Nicodemi M, Gamba A. Dynamic membrane patterning, signal localization and polarity in living cells. SOFT MATTER 2015; 11:838-849. [PMID: 25563791 DOI: 10.1039/c4sm02157f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We review the molecular and physical aspects of the dynamic localization of signaling molecules on the plasma membranes of living cells. At the nanoscale, clusters of receptors and signaling proteins play an essential role in the processing of extracellular signals. At the microscale, "soft" and highly dynamic signaling domains control the interaction of individual cells with their environment. At the multicellular scale, individual polarity patterns control the forces that shape multicellular aggregates and tissues.
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Affiliation(s)
- M Zamparo
- Human Genetics Foundation - Torino, Italy.
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