TY - JOUR AB - Tissue morphogenesis and patterning during development involve the segregation of cell types. Segregation is driven by differential tissue surface tensions generated by cell types through controlling cell-cell contact formation by regulating adhesion and actomyosin contractility-based cellular cortical tensions. We use vertebrate tissue cell types and zebrafish germ layer progenitors as in vitro models of 3-dimensional heterotypic segregation and developed a quantitative analysis of their dynamics based on 3D time-lapse microscopy. We show that general inhibition of actomyosin contractility by the Rho kinase inhibitor Y27632 delays segregation. Cell type-specific inhibition of non-muscle myosin2 activity by overexpression of myosin assembly inhibitor S100A4 reduces tissue surface tension, manifested in decreased compaction during aggregation and inverted geometry observed during segregation. The same is observed when we express a constitutively active Rho kinase isoform to ubiquitously keep actomyosin contractility high at cell-cell and cell-medium interfaces and thus overriding the interface-specific regulation of cortical tensions. Tissue surface tension regulation can become an effective tool in tissue engineering. AU - Méhes, Elod AU - Mones, Enys AU - Varga, Máté AU - Zsigmond, Áron AU - Biri-Kovács, Beáta AU - Nyitray, László AU - Barone, Vanessa AU - Krens, Gabriel AU - Heisenberg, Carl-Philipp J AU - Vicsek, Tamás ID - 14041 JF - Communications Biology TI - 3D cell segregation geometry and dynamics are governed by tissue surface tension regulation VL - 6 ER - TY - JOUR AB - Lymph nodes (LNs) comprise two main structural elements: fibroblastic reticular cells that form dedicated niches for immune cell interaction and capsular fibroblasts that build a shell around the organ. Immunological challenge causes LNs to increase more than tenfold in size within a few days. Here, we characterized the biomechanics of LN swelling on the cellular and organ scale. We identified lymphocyte trapping by influx and proliferation as drivers of an outward pressure force, causing fibroblastic reticular cells of the T-zone (TRCs) and their associated conduits to stretch. After an initial phase of relaxation, TRCs sensed the resulting strain through cell matrix adhesions, which coordinated local growth and remodeling of the stromal network. While the expanded TRC network readopted its typical configuration, a massive fibrotic reaction of the organ capsule set in and countered further organ expansion. Thus, different fibroblast populations mechanically control LN swelling in a multitier fashion. AU - Assen, Frank P AU - Abe, Jun AU - Hons, Miroslav AU - Hauschild, Robert AU - Shamipour, Shayan AU - Kaufmann, Walter AU - Costanzo, Tommaso AU - Krens, Gabriel AU - Brown, Markus AU - Ludewig, Burkhard AU - Hippenmeyer, Simon AU - Heisenberg, Carl-Philipp J AU - Weninger, Wolfgang AU - Hannezo, Edouard B AU - Luther, Sanjiv A. AU - Stein, Jens V. AU - Sixt, Michael K ID - 9794 JF - Nature Immunology SN - 1529-2908 TI - Multitier mechanics control stromal adaptations in swelling lymph nodes VL - 23 ER - TY - JOUR AB - Tension of the actomyosin cell cortex plays a key role in determining cell–cell contact growth and size. The level of cortical tension outside of the cell–cell contact, when pulling at the contact edge, scales with the total size to which a cell–cell contact can grow [J.-L. Maître et al., Science 338, 253–256 (2012)]. Here, we show in zebrafish primary germ-layer progenitor cells that this monotonic relationship only applies to a narrow range of cortical tension increase and that above a critical threshold, contact size inversely scales with cortical tension. This switch from cortical tension increasing to decreasing progenitor cell–cell contact size is caused by cortical tension promoting E-cadherin anchoring to the actomyosin cytoskeleton, thereby increasing clustering and stability of E-cadherin at the contact. After tension-mediated E-cadherin stabilization at the contact exceeds a critical threshold level, the rate by which the contact expands in response to pulling forces from the cortex sharply drops, leading to smaller contacts at physiologically relevant timescales of contact formation. Thus, the activity of cortical tension in expanding cell–cell contact size is limited by tension-stabilizing E-cadherin–actin complexes at the contact. AU - Slovakova, Jana AU - Sikora, Mateusz K AU - Arslan, Feyza N AU - Caballero Mancebo, Silvia AU - Krens, Gabriel AU - Kaufmann, Walter AU - Merrin, Jack AU - Heisenberg, Carl-Philipp J ID - 10766 IS - 8 JF - Proceedings of the National Academy of Sciences of the United States of America TI - Tension-dependent stabilization of E-cadherin limits cell-cell contact expansion in zebrafish germ-layer progenitor cells VL - 119 ER - TY - JOUR AB - A modern day light microscope has evolved from a tool devoted to making primarily empirical observations to what is now a sophisticated , quantitative device that is an integral part of both physical and life science research. Nowadays, microscopes are found in nearly every experimental laboratory. However, despite their prevalent use in capturing and quantifying scientific phenomena, neither a thorough understanding of the principles underlying quantitative imaging techniques nor appropriate knowledge of how to calibrate, operate and maintain microscopes can be taken for granted. This is clearly demonstrated by the well-documented and widespread difficulties that are routinely encountered in evaluating acquired data and reproducing scientific experiments. Indeed, studies have shown that more than 70% of researchers have tried and failed to repeat another scientist's experiments, while more than half have even failed to reproduce their own experiments. One factor behind the reproducibility crisis of experiments published in scientific journals is the frequent underreporting of imaging methods caused by a lack of awareness and/or a lack of knowledge of the applied technique. Whereas quality control procedures for some methods used in biomedical research, such as genomics (e.g. DNA sequencing, RNA-seq) or cytometry, have been introduced (e.g. ENCODE), this issue has not been tackled for optical microscopy instrumentation and images. Although many calibration standards and protocols have been published, there is a lack of awareness and agreement on common standards and guidelines for quality assessment and reproducibility. In April 2020, the QUality Assessment and REProducibility for instruments and images in Light Microscopy (QUAREP-LiMi) initiative was formed. This initiative comprises imaging scientists from academia and industry who share a common interest in achieving a better understanding of the performance and limitations of microscopes and improved quality control (QC) in light microscopy. The ultimate goal of the QUAREP-LiMi initiative is to establish a set of common QC standards, guidelines, metadata models and tools, including detailed protocols, with the ultimate aim of improving reproducible advances in scientific research. This White Paper (1) summarizes the major obstacles identified in the field that motivated the launch of the QUAREP-LiMi initiative; (2) identifies the urgent need to address these obstacles in a grassroots manner, through a community of stakeholders including, researchers, imaging scientists, bioimage analysts, bioimage informatics developers, corporate partners, funding agencies, standards organizations, scientific publishers and observers of such; (3) outlines the current actions of the QUAREP-LiMi initiative and (4) proposes future steps that can be taken to improve the dissemination and acceptance of the proposed guidelines to manage QC. To summarize, the principal goal of the QUAREP-LiMi initiative is to improve the overall quality and reproducibility of light microscope image data by introducing broadly accepted standard practices and accurately captured image data metrics. AU - Nelson, Glyn AU - Boehm, Ulrike AU - Bagley, Steve AU - Bajcsy, Peter AU - Bischof, Johanna AU - Brown, Claire M. AU - Dauphin, Aurélien AU - Dobbie, Ian M. AU - Eriksson, John E. AU - Faklaris, Orestis AU - Fernandez-Rodriguez, Julia AU - Ferrand, Alexia AU - Gelman, Laurent AU - Gheisari, Ali AU - Hartmann, Hella AU - Kukat, Christian AU - Laude, Alex AU - Mitkovski, Miso AU - Munck, Sebastian AU - North, Alison J. AU - Rasse, Tobias M. AU - Resch-Genger, Ute AU - Schuetz, Lucas C. AU - Seitz, Arne AU - Strambio-De-Castillia, Caterina AU - Swedlow, Jason R. AU - Alexopoulos, Ioannis AU - Aumayr, Karin AU - Avilov, Sergiy AU - Bakker, Gert Jan AU - Bammann, Rodrigo R. AU - Bassi, Andrea AU - Beckert, Hannes AU - Beer, Sebastian AU - Belyaev, Yury AU - Bierwagen, Jakob AU - Birngruber, Konstantin A. AU - Bosch, Manel AU - Breitlow, Juergen AU - Cameron, Lisa A. AU - Chalfoun, Joe AU - Chambers, James J. AU - Chen, Chieh Li AU - Conde-Sousa, Eduardo AU - Corbett, Alexander D. AU - Cordelieres, Fabrice P. AU - Nery, Elaine Del AU - Dietzel, Ralf AU - Eismann, Frank AU - Fazeli, Elnaz AU - Felscher, Andreas AU - Fried, Hans AU - Gaudreault, Nathalie AU - Goh, Wah Ing AU - Guilbert, Thomas AU - Hadleigh, Roland AU - Hemmerich, Peter AU - Holst, Gerhard A. AU - Itano, Michelle S. AU - Jaffe, Claudia B. AU - Jambor, Helena K. AU - Jarvis, Stuart C. AU - Keppler, Antje AU - Kirchenbuechler, David AU - Kirchner, Marcel AU - Kobayashi, Norio AU - Krens, Gabriel AU - Kunis, Susanne AU - Lacoste, Judith AU - Marcello, Marco AU - Martins, Gabriel G. AU - Metcalf, Daniel J. AU - Mitchell, Claire A. AU - Moore, Joshua AU - Mueller, Tobias AU - Nelson, Michael S. AU - Ogg, Stephen AU - Onami, Shuichi AU - Palmer, Alexandra L. AU - Paul-Gilloteaux, Perrine AU - Pimentel, Jaime A. AU - Plantard, Laure AU - Podder, Santosh AU - Rexhepaj, Elton AU - Royon, Arnaud AU - Saari, Markku A. AU - Schapman, Damien AU - Schoonderwoert, Vincent AU - Schroth-Diez, Britta AU - Schwartz, Stanley AU - Shaw, Michael AU - Spitaler, Martin AU - Stoeckl, Martin T. AU - Sudar, Damir AU - Teillon, Jeremie AU - Terjung, Stefan AU - Thuenauer, Roland AU - Wilms, Christian D. AU - Wright, Graham D. AU - Nitschke, Roland ID - 9911 IS - 1 JF - Journal of Microscopy SN - 0022-2720 TI - QUAREP-LiMi: A community-driven initiative to establish guidelines for quality assessment and reproducibility for instruments and images in light microscopy VL - 284 ER - TY - GEN AB - Tension of the actomyosin cell cortex plays a key role in determining cell-cell contact growth and size. The level of cortical tension outside of the cell-cell contact, when pulling at the contact edge, scales with the total size to which a cell-cell contact can grow1,2. Here we show in zebrafish primary germ layer progenitor cells that this monotonic relationship only applies to a narrow range of cortical tension increase, and that above a critical threshold, contact size inversely scales with cortical tension. This switch from cortical tension increasing to decreasing progenitor cell-cell contact size is caused by cortical tension promoting E-cadherin anchoring to the actomyosin cytoskeleton, thereby increasing clustering and stability of E-cadherin at the contact. Once tension-mediated E-cadherin stabilization at the contact exceeds a critical threshold level, the rate by which the contact expands in response to pulling forces from the cortex sharply drops, leading to smaller contacts at physiologically relevant timescales of contact formation. Thus, the activity of cortical tension in expanding cell-cell contact size is limited by tension stabilizing E-cadherin-actin complexes at the contact. AU - Slovakova, Jana AU - Sikora, Mateusz K AU - Caballero Mancebo, Silvia AU - Krens, Gabriel AU - Kaufmann, Walter AU - Huljev, Karla AU - Heisenberg, Carl-Philipp J ID - 9750 T2 - bioRxiv TI - Tension-dependent stabilization of E-cadherin limits cell-cell contact expansion ER - TY - JOUR AB - Migrating cells penetrate tissue barriers during development, inflammatory responses, and tumor metastasis. We study if migration in vivo in such three-dimensionally confined environments requires changes in the mechanical properties of the surrounding cells using embryonic Drosophila melanogaster hemocytes, also called macrophages, as a model. We find that macrophage invasion into the germband through transient separation of the apposing ectoderm and mesoderm requires cell deformations and reductions in apical tension in the ectoderm. Interestingly, the genetic pathway governing these mechanical shifts acts downstream of the only known tumor necrosis factor superfamily member in Drosophila, Eiger, and its receptor, Grindelwald. Eiger-Grindelwald signaling reduces levels of active Myosin in the germband ectodermal cortex through the localization of a Crumbs complex component, Patj (Pals-1-associated tight junction protein). We therefore elucidate a distinct molecular pathway that controls tissue tension and demonstrate the importance of such regulation for invasive migration in vivo. AU - Ratheesh, Aparna AU - Biebl, Julia AU - Smutny, Michael AU - Veselá, Jana AU - Papusheva, Ekaterina AU - Krens, Gabriel AU - Kaufmann, Walter AU - György, Attila AU - Casano, Alessandra M AU - Siekhaus, Daria E ID - 308 IS - 3 JF - Developmental Cell TI - Drosophila TNF modulates tissue tension in the embryo to facilitate macrophage invasive migration VL - 45 ER - TY - JOUR AB - The rapid auxin-triggered growth of the Arabidopsis hypocotyls involves the nuclear TIR1/AFB-Aux/IAA signaling and is accompanied by acidification of the apoplast and cell walls (Fendrych et al., 2016). Here, we describe in detail the method for analysis of the elongation and the TIR1/AFB-Aux/IAA-dependent auxin response in hypocotyl segments as well as the determination of relative values of the cell wall pH. AU - Li, Lanxin AU - Krens, Gabriel AU - Fendrych, Matyas AU - Friml, Jirí ID - 442 IS - 1 JF - Bio-protocol TI - Real-time analysis of auxin response, cell wall pH and elongation in Arabidopsis thaliana Hypocotyls VL - 8 ER - TY - JOUR AB - Embryo morphogenesis relies on highly coordinated movements of different tissues. However, remarkably little is known about how tissues coordinate their movements to shape the embryo. In zebrafish embryogenesis, coordinated tissue movements first become apparent during “doming,” when the blastoderm begins to spread over the yolk sac, a process involving coordinated epithelial surface cell layer expansion and mesenchymal deep cell intercalations. Here, we find that active surface cell expansion represents the key process coordinating tissue movements during doming. By using a combination of theory and experiments, we show that epithelial surface cells not only trigger blastoderm expansion by reducing tissue surface tension, but also drive blastoderm thinning by inducing tissue contraction through radial deep cell intercalations. Thus, coordinated tissue expansion and thinning during doming relies on surface cells simultaneously controlling tissue surface tension and radial tissue contraction. AU - Morita, Hitoshi AU - Grigolon, Silvia AU - Bock, Martin AU - Krens, Gabriel AU - Salbreux, Guillaume AU - Heisenberg, Carl-Philipp J ID - 1067 IS - 4 JF - Developmental Cell SN - 15345807 TI - The physical basis of coordinated tissue spreading in zebrafish gastrulation VL - 40 ER - TY - JOUR AB - The segregation of different cell types into distinct tissues is a fundamental process in metazoan development. Differences in cell adhesion and cortex tension are commonly thought to drive cell sorting by regulating tissue surface tension (TST). However, the role that differential TST plays in cell segregation within the developing embryo is as yet unclear. Here, we have analyzed the role of differential TST for germ layer progenitor cell segregation during zebrafish gastrulation. Contrary to previous observations that differential TST drives germ layer progenitor cell segregation in vitro, we show that germ layers display indistinguishable TST within the gastrulating embryo, arguing against differential TST driving germ layer progenitor cell segregation in vivo. We further show that the osmolarity of the interstitial fluid (IF) is an important factor that influences germ layer TST in vivo, and that lower osmolarity of the IF compared with standard cell culture medium can explain why germ layers display differential TST in culture but not in vivo. Finally, we show that directed migration of mesendoderm progenitors is required for germ layer progenitor cell segregation and germ layer formation. AU - Krens, Gabriel AU - Veldhuis, Jim AU - Barone, Vanessa AU - Capek, Daniel AU - Maître, Jean-Léon AU - Brodland, Wayne AU - Heisenberg, Carl-Philipp J ID - 676 IS - 10 JF - Development SN - 09501991 TI - Interstitial fluid osmolarity modulates the action of differential tissue surface tension in progenitor cell segregation during gastrulation VL - 144 ER - TY - JOUR AB - Cell-cell contact formation constitutes an essential step in evolution, leading to the differentiation of specialized cell types. However, remarkably little is known about whether and how the interplay between contact formation and fate specification affects development. Here, we identify a positive feedback loop between cell-cell contact duration, morphogen signaling, and mesendoderm cell-fate specification during zebrafish gastrulation. We show that long-lasting cell-cell contacts enhance the competence of prechordal plate (ppl) progenitor cells to respond to Nodal signaling, required for ppl cell-fate specification. We further show that Nodal signaling promotes ppl cell-cell contact duration, generating a positive feedback loop between ppl cell-cell contact duration and cell-fate specification. Finally, by combining mathematical modeling and experimentation, we show that this feedback determines whether anterior axial mesendoderm cells become ppl or, instead, turn into endoderm. Thus, the interdependent activities of cell-cell signaling and contact formation control fate diversification within the developing embryo. AU - Barone, Vanessa AU - Lang, Moritz AU - Krens, Gabriel AU - Pradhan, Saurabh AU - Shamipour, Shayan AU - Sako, Keisuke AU - Sikora, Mateusz K AU - Guet, Calin C AU - Heisenberg, Carl-Philipp J ID - 735 IS - 2 JF - Developmental Cell SN - 15345807 TI - An effective feedback loop between cell-cell contact duration and morphogen signaling determines cell fate VL - 43 ER - TY - JOUR AB - Vertebrates have a unique 3D body shape in which correct tissue and organ shape and alignment are essential for function. For example, vision requires the lens to be centred in the eye cup which must in turn be correctly positioned in the head. Tissue morphogenesis depends on force generation, force transmission through the tissue, and response of tissues and extracellular matrix to force. Although a century ago D'Arcy Thompson postulated that terrestrial animal body shapes are conditioned by gravity, there has been no animal model directly demonstrating how the aforementioned mechano-morphogenetic processes are coordinated to generate a body shape that withstands gravity. Here we report a unique medaka fish (Oryzias latipes) mutant, hirame (hir), which is sensitive to deformation by gravity. hir embryos display a markedly flattened body caused by mutation of YAP, a nuclear executor of Hippo signalling that regulates organ size. We show that actomyosin-mediated tissue tension is reduced in hir embryos, leading to tissue flattening and tissue misalignment, both of which contribute to body flattening. By analysing YAP function in 3D spheroids of human cells, we identify the Rho GTPase activating protein ARHGAP18 as an effector of YAP in controlling tissue tension. Together, these findings reveal a previously unrecognised function of YAP in regulating tissue shape and alignment required for proper 3D body shape. Understanding this morphogenetic function of YAP could facilitate the use of embryonic stem cells to generate complex organs requiring correct alignment of multiple tissues. AU - Porazinski, Sean AU - Wang, Huijia AU - Asaoka, Yoichi AU - Behrndt, Martin AU - Miyamoto, Tatsuo AU - Morita, Hitoshi AU - Hata, Shoji AU - Sasaki, Takashi AU - Krens, Gabriel AU - Osada, Yumi AU - Asaka, Satoshi AU - Momoi, Akihiro AU - Linton, Sarah AU - Miesfeld, Joel AU - Link, Brian AU - Senga, Takeshi AU - Castillo Morales, Atahualpa AU - Urrutia, Araxi AU - Shimizu, Nobuyoshi AU - Nagase, Hideaki AU - Matsuura, Shinya AU - Bagby, Stefan AU - Kondoh, Hisato AU - Nishina, Hiroshi AU - Heisenberg, Carl-Philipp J AU - Furutani Seiki, Makoto ID - 1817 IS - 7551 JF - Nature TI - YAP is essential for tissue tension to ensure vertebrate 3D body shape VL - 521 ER - TY - JOUR AU - Maître, Jean-Léon AU - Berthoumieux, Hélène AU - Krens, Gabriel AU - Salbreux, Guillaume AU - Julicher, Frank AU - Paluch, Ewa AU - Heisenberg, Carl-Philipp J ID - 2884 IS - 2 JF - Medecine Sciences TI - Cell adhesion mechanics of zebrafish gastrulation VL - 29 ER - TY - JOUR AB - Differential cell adhesion and cortex tension are thought to drive cell sorting by controlling cell-cell contact formation. Here, we show that cell adhesion and cortex tension have different mechanical functions in controlling progenitor cell-cell contact formation and sorting during zebrafish gastrulation. Cortex tension controls cell-cell contact expansion by modulating interfacial tension at the contact. By contrast, adhesion has little direct function in contact expansion, but instead is needed to mechanically couple the cortices of adhering cells at their contacts, allowing cortex tension to control contact expansion. The coupling function of adhesion is mediated by E-cadherin and limited by the mechanical anchoring of E-cadherin to the cortex. Thus, cell adhesion provides the mechanical scaffold for cell cortex tension to drive cell sorting during gastrulation. AU - Maître, Jean-Léon AU - Berthoumieux, Hélène AU - Krens, Gabriel AU - Salbreux, Guillaume AU - Julicher, Frank AU - Paluch, Ewa AU - Heisenberg, Carl-Philipp J ID - 2951 IS - 6104 JF - Science TI - Adhesion functions in cell sorting by mechanically coupling the cortices of adhering cells VL - 338 ER - TY - JOUR AB - Tissue surface tension (TST) is an important mechanical property influencing cell sorting and tissue envelopment. The study by Manning et al. (1) reported on a mathematical model describing TST on the basis of the balance between adhesive and tensile properties of the constituent cells. The model predicts that, in high-adhesion cell aggregates, surface cells will be stretched to maintain the same area of cell–cell contact as interior bulk cells, resulting in an elongated and flattened cell shape. The authors (1) observed flat and elongated cells at the surface of high-adhesion zebrafish germ-layer explants, which they argue are undifferentiated stretched germ-layer progenitor cells, and they use this observation as a validation of their model. AU - Krens, Gabriel AU - Möllmert, Stephanie AU - Heisenberg, Carl-Philipp J ID - 3368 IS - 3 JF - PNAS TI - Enveloping cell layer differentiation at the surface of zebrafish germ layer tissue explants VL - 108 ER - TY - CHAP AB - During the development of multicellular organisms, cell fate specification is followed by the sorting of different cell types into distinct domains from where the different tissues and organs are formed. Cell sorting involves both the segregation of a mixed population of cells with different fates and properties into distinct domains, and the active maintenance of their segregated state. Because of its biological importance and apparent resemblance to fluid segregation in physics, cell sorting was extensively studied by both biologists and physicists over the last decades. Different theories were developed that try to explain cell sorting on the basis of the physical properties of the constituent cells. However, only recently the molecular and cellular mechanisms that control the physical properties driving cell sorting, have begun to be unraveled. In this review, we will provide an overview of different cell-sorting processes in development and discuss how these processes can be explained by the different sorting theories, and how these theories in turn can be connected to the molecular and cellular mechanisms driving these processes. AU - Krens, Gabriel AU - Heisenberg, Carl-Philipp J ED - Labouesse, Michel ID - 3791 T2 - Forces and Tension in Development TI - Cell sorting in development VL - 95 ER - TY - JOUR AB - Cell sorting is a widespread phenomenon pivotal to the early development of multicellular organisms. In vitro cell sorting studies have been instrumental in revealing the cellular properties driving this process. However, these studies have as yet been limited to two-dimensional analysis of three-dimensional cell sorting events. Here we describe a method to record the sorting of primary zebrafish ectoderm and mesoderm germ layer progenitor cells in three dimensions over time, and quantitatively analyze their sorting behavior using an order parameter related to heterotypic interface length. We investigate the cell population size dependence of sorted aggregates and find that the germ layer progenitor cells engulfed in the final configuration display a relationship between total interfacial length and system size according to a simple geometrical argument, subject to a finite-size effect. AU - Klopper, Abigail AU - Krens, Gabriel AU - Grill, Stephan AU - Heisenberg, Carl-Philipp J ID - 3788 IS - 2 JF - The European Physical Journal E: Soft Matter and Biological Physics TI - Finite-size corrections to scaling behavior in sorted cell aggregates VL - 33 ER -