Collective Migration Research Articles

Tissue Active Matter: Integrating Mechanics and Signaling into Dynamical Models.

The importance of physical forces in the morphogenesis, homeostatic function, and pathological dysfunction of multicellular tissues is being increasingly characterized, both theoretically and experimentally. Analogies between biological systems and inert materials such as foams, gels, and liquid crystals have provided striking insights into the core design principles underlying multicellular organization. However, these connections can seem surprising given that a key feature of multicellular systems is their ability to constantly consume energy, providing an active origin for the forces that they produce. Key emerging questions are, therefore, to understand whether and how this activity grants tissues novel properties that do not have counterparts in classical materials, as well as their consequences for biological function. Here, we review recent discoveries at the intersection of active matter and tissue biology, with an emphasis on how modeling and experiments can be combined to understand the dynamics of multicellular systems. These approaches suggest that a number of key biological tissue-scale phenomena, such as morphogenetic shape changes, collective migration, or fate decisions, share unifying design principles that can be described by physical models of tissue active matter.

Nanoparticle's Encapsulation As a Marker for Leading Cells in Collective Migration of Breast Cancer Cells

Nanoparticle's Encapsulation As a Marker for Leading Cells in Collective Migration of Breast Cancer Cells

Long-distance communication can enable collective migration in a dynamic seascape

Social information is predicted to enhance the quality of animals’ migratory decisions in dynamic ecosystems, but the relative benefits of social information in the long-range movements of marine megafauna are unknown. In particular, whether and how migrants use nonlocal information gained through social communication at the large spatial scale of oceanic ecosystems remains unclear. Here we test hypotheses about the cues underlying timing of blue whales’ breeding migration in the Northeast Pacific via individual-based models parameterized by empirical behavioral data. Comparing emergent patterns from individual-based models to individual and population-level empirical metrics of migration timing, we find that individual whales likely rely on both personal and social sources of information about forage availability in deciding when to depart from their vast and dynamic foraging habitat and initiate breeding migration. Empirical patterns of migratory phenology can only be reproduced by models in which individuals use long-distance social information about conspecifics’ behavioral state, which is known to be encoded in the patterning of their widely propagating songs. Further, social communication improves pre-migration seasonal foraging performance by over 60% relative to asocial movement mechanisms. Our results suggest that long-range communication enhances the perceptual ranges of migrating whales beyond that of any individual, resulting in increased foraging performance and more collective migration timing. These findings indicate the value of nonlocal social information in an oceanic migrant and suggest the importance of long-distance acoustic communication in the collective migration of wide-ranging marine megafauna.

Role of tissue fluidization and topological defects in epithelial tubulogenesis

Cellular rearrangements, as primary sources of tissue fluidization, facilitate topological transitions during tissue morphogenesis. We study the role of intrinsic cell properties such as cell polarity and cell-cell adhesion in shaping epithelial tissues using a minimal model of interacting polarized cells. The presence of a vortex in the cell polarization poses the topological constraint that induces an inwards migration with the formation of a conical shape. Local rearrangements at the tip of the cone lead to the onset of tube formation. Switching between collective migration and structural rearrangements is key for balancing the contrasting tendencies, such as the tissue rigidity needed to preserve shape and the tissue fluidity allowing for topological transitions during tissue morphogenesis. Published by the American Physical Society 2024

Optimal Control of Collective Electrotaxis in Epithelial Monolayers

Epithelial monolayers are some of the best-studied models for collective cell migration due to their abundance in multicellular systems and their tractability. Experimentally, the collective migration of epithelial monolayers can be robustly steered e.g. using electric fields, via a process termed electrotaxis. Theoretically, however, the question of how to design an electric field to achieve a desired spatiotemporal movement pattern is underexplored. In this work, we construct and calibrate an ordinary differential equation model to predict the average velocity of the centre of mass of a cellular monolayer in response to stimulation with an electric field. We use this model, in conjunction with optimal control theory, to derive physically realistic optimal electric field designs to achieve a variety of aims, including maximising the total distance travelled by the monolayer, maximising the monolayer velocity, and keeping the monolayer velocity constant during stimulation. Together, this work is the first to present a unified framework for optimal control of collective monolayer electrotaxis and provides a blueprint to optimally steer collective migration using other external cues.

MEK inhibitors and DA-Raf, a dominant-negative antagonist of the Ras-ERK pathway, prevent the migration and invasion of KRAS-mutant cancer cells.

The Ras-induced ERK pathway (Raf-MEK-ERK signaling cascade) regulates a variety of cellular responses including cell proliferation, survival, and migration. Activating mutations in RAS genes, particularly in the KRAS gene, constitutively activate the ERK pathway, resulting in tumorigenesis, cancer cell invasion, and metastasis. DA-Raf1 (DA-Raf) is a splicing isoform of A-Raf and contains the Ras-binding domain but lacks the kinase domain. Consequently, DA-Raf antagonizes the Ras-ERK pathway in a dominant-negative manner and can serve as a tumor suppressor that targets mutant Ras protein-induced tumorigenesis. We show here that MEK inhibitors and DA-Raf interfere with the in vitro collective cell migration and invasion of human KRAS-mutant carcinoma cell lines, the lung adenocarcinoma A549, colorectal carcinoma HCT116, and pancreatic carcinoma MIA PaCa-2 cells. DA-Raf expression was silenced in these cancer cell lines. All these cell lines had high collective migration abilities and invasion properties in Matrigel, compared with nontumor cells. Their migration and invasion abilities were impaired by suppressing the ERK pathway with the MEK inhibitors U0126 and trametinib, an approved anticancer drug. Expression of DA-Raf in MIA PaCa-2 cells reduced the ERK activity and hindered the migration and invasion abilities. Therefore, DA-Raf may function as an invasion suppressor protein in the KRAS-mutant cancer cells by blocking the Ras-ERK pathway when DA-Raf expression is induced in invasive cancer cells.

The Balance Between Shear Flow and Extracellular Matrix in Ovarian Cancer-on-Chip.

Ovarian cancer is the most lethal gynecologic cancer in developed countries. In the tumor microenvironment, the extracellular matrix (ECM) and flow shear stress are key players in directing ovarian cancer cells invasion. Artificial ECM models based only on ECM proteins are used to build an ovarian tumor-on-chip to decipher the crosstalk between ECM and shear stress on the migratory behavior and cellular heterogeneity of ovarian tumor cells. This work shows that in the shear stress regime of the peritoneal cavity, the ECM plays a major role in driving individual or collective ovarian tumor cells migration. In the presence of basement membrane proteins, migration is more collective than on type I collagen regardless of shear stress. With increasing shear stress, individual cell migration is enhanced; while, no significant impact on collective migration is measured. This highlights the central position that ECM and flow shear stress should hold in in vitro ovarian cancer models to deepen understanding of cellular responses and improve development of ovarian cancer therapeutic platforms. In this frame, adding flow provides significant improvement in biological relevance over the authors' previous work. Further steps for enhanced clinical relevance require not only multiple cell lines but also patient-derived cells and sera.

Neuraminidase inhibition promotes the collective migration of neurons and recovery of brain function

In the injured brain, new neurons produced from endogenous neural stem cells form chains and migrate to injured areas and contribute to the regeneration of lost neurons. However, this endogenous regenerative capacity of the brain has not yet been leveraged for the treatment of brain injury. Here, we show that in healthy brain chains of migrating new neurons maintain unexpectedly large non-adherent areas between neighboring cells, allowing for efficient migration. In instances of brain injury, neuraminidase reduces polysialic acid levels, which negatively regulates adhesion, leading to increased cell–cell adhesion and reduced migration efficiency. The administration of zanamivir, a neuraminidase inhibitor used for influenza treatment, promotes neuronal migration toward damaged regions, fosters neuronal regeneration, and facilitates functional recovery. Together, these findings shed light on a new mechanism governing efficient neuronal migration in the adult brain under physiological conditions, pinpoint the disruption of this mechanism during brain injury, and propose a promising therapeutic avenue for brain injury through drug repositioning.

Label-Free Interference Imaging of Intracellular Trafficking.

Intracellular cargo trafficking is a highly regulated process responsible for transporting vital cellular components to their designated destinations. This intricate journey has been a central focus of cellular biology for many years. Early investigations leaned heavily on biochemical and genetic approaches, offering valuable insight into molecular mechanisms of cellular trafficking. However, while informative, these methods lack the capacity to capture the dynamic nature of intracellular trafficking. The advent of fluorescent protein tagging techniques transformed our ability to monitor the complete lifecycle of intracellular cargos, advancing our understanding. Yet, a central question remains: How do these cargos manage to navigate through traffic challenges, such as congestion, within the crowded cellular environment? Fluorescence-based imaging, though valuable, has inherent limitations when it comes to addressing the aforementioned question. It is prone to photobleaching, making long-term live-cell imaging challenging. Furthermore, they render unlabeled cellular constituents invisible, thereby missing critical environmental information. Notably, the unlabeled majority likely exerts a significant influence on the observed behavior of labeled molecules. These considerations underscore the necessity of developing complementary label-free imaging methods to overcome the limitations of fluorescence imaging or to integrate them synergistically.In this Account, we outline how label-free interference-based imaging has the potential to revolutionize the study of intracellular traffic by offering unprecedented levels of detail. We begin with a brief introduction to our previous findings in live-cell research enabled by interferometric scattering (iSCAT) microscopy, showcasing its aptitude and adeptness in elucidating intricate nanoscale intracellular structures. As we delved deeper into our exploration, we succeeded in the label-free visualization of the entire lifespan of nanoscale protein complexes known as nascent adhesions (NAs) and the dynamic events associated with adhesions within living cells. Our continuous efforts have led to the development of Dynamic Scattering-particle Localization Interference Microscopy (DySLIM), a generalized concept of cargo-localization iSCAT (CL-iSCAT). This label-free, high-speed imaging method, armed with iSCAT detection sensitivity, empowers us to capture quantitative and biophysical insights into cargo transport, providing a realistic view of the intricate nanoscale logistics occurring within living cells. Our in vivo studies demonstrate that intracellular cargos regularly contend with substantial traffic within the crowded cellular environment. Simultaneously, they employ inherent strategies for efficient cargo transport, such as collective migration and hitchhiking, to enhance overall transport rates─intriguingly paralleling the principle and practice of urban traffic management. We also highlight the synergistic benefits of combining DySLIM with chemical-selective fluorescent methods. This Account concludes with a "Conclusions and Outlook" section, outlining promising directions for future research and developments, with a particular emphasis on the functional application of iSCAT live-cell imaging. We aim to inspire further investigation into the efficient transport strategies employed by cells to surmount transportation challenges, shedding light on their significance in cellular phenomena.

Abstract B025: Luminal-to-basal phenotypic plasticity promotes invasive phenotypes in a live-imaging assay using patient-derived bladder tumor organoids

Abstract Lineage plasticity in cancer is characterized by changes in cell state that are often associated with tumor progression and treatment resistance. While nearly all non-muscle invasive bladder cancer (NMIBC) tumors have a luminal epithelial phenotype, many muscle invasive bladder cancers (MIBC) display a basal identity. NMIBC to MIBC progression may therefore be related to a phenotypic switch from luminal-to-basal subtypes, which in turn may be associated with poorer clinical outcomes. However, current understanding of the molecular processes linking cell plasticity and tumor invasion is limited, due in part to a lack of physiologically relevant in vitro models and assays. To address these questions, we are utilizing a living biobank of 82 patient-derived bladder tumor organoid lines that our group has established. These organoids represent a 3-dimensional, heterogeneous model system for studying bladder cancer, as they can be genetically manipulated and recapitulate the molecular and histopathological features of the parental tumor. Notably, in previous work, we described luminal-to-basal phenotypic plasticity in a subset of organoid lines derived from luminal tumors, which display a shift to basal/squamous identity in culture that is reversible by orthotopic xenografting. In current studies, we are investigating cell migration and invasiveness using a live-imaging assay that we have developed to examine bladder tumor organoid outgrowth in vitro. Importantly, this assay allows longitudinal visualization as well as quantitation of invasiveness over a four-day time span. Analysis of over 25 organoid lines with plastic, stable luminal, and stable basal properties has revealed a broad spectrum of organoid outgrowth phenotypes that do not correlate with cell proliferation or clinical parameters. Instead, the degree of outgrowth correlates precisely with luminal-to-basal phenotypic plasticity, as assessed by transcriptome analyses, immunofluorescence microscopy, and in vivo xenografting. Organoid lines with minimal outgrowth have stable luminal phenotypes, whereas lines that produce their own extracellular matrix to create a leading edge of migrating cells have plastic phenotypes. Furthermore, movies of the invading organoids reveal distinct cell migratory patterns, as several organoid lines display collective migration that generates an invasive front at the leading edge. This collective migration phenotype is distinct from phenotypic plasticity, is at least partially independent from organoid outgrowth, and is undergoing further analysis. Thus, our organoid outgrowth assay identifies two different parameters of invasive potential, one of which correlates with phenotypic plasticity. Our findings characterize bladder tumor invasion patterns for the first time and suggest that lineage plasticity in NMIBC represents a key mechanism that promotes tumor invasion in MIBC. Citation Format: Clementine Le Coz, John R. Christin, Talal Syed, Zejian Wang, Caroline J. Laplaca, Andrew T. Lenis, Michael M. Shen. Luminal-to-basal phenotypic plasticity promotes invasive phenotypes in a live-imaging assay using patient-derived bladder tumor organoids [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr B025.

Two sequential gene expression programs bridged by cell division support long-distance collective cell migration.

The precise assembly of tissues and organs relies on spatiotemporal regulation of gene expression to coordinate the collective behavior of cells. In Drosophila embryos, the midgut musculature is formed through collective migration of caudal visceral mesoderm (CVM) cells, but how gene expression changes as cells migrate is not well understood. Here, we have focused on ten genes expressed in the CVM and the cis-regulatory sequences controlling their expression. Although some genes are continuously expressed, others are expressed only early or late during migration. Late expression relates to cell cycle progression, as driving string/Cdc25 causes earlier division of CVM cells and accelerates the transition to late gene expression. In particular, we found that the cell cycle effector transcription factor E2F1 is a required input for the late gene CG5080. Furthermore, whereas late genes are broadly expressed in all CVM cells, early gene transcripts are polarized to the anterior or posterior ends of the migrating collective. We show this polarization requires transcription factors Snail, Zfh1 and Dorsocross. Collectively, these results identify two sequential gene expression programs bridged by cell division that support long-distance directional migration of CVM cells.

The people behind the papers - Jingjing Sun and Angelike Stathopoulos.

Collective migration of caudal visceral mesoderm (CVM) cells in Drosophila embryos helps form the longitudinal muscles of the larval gut. In their study, Angelike Stathopoulos and colleagues reveal that cell division coordinates two gene expression programmes in migrating CVM cells. To know more about their work, we spoke to the first author, Jingjing Sun, and the corresponding author, Angelike Stathopoulos, Professor in the Division of Biology at the California Institute of Technology, USA.

Exchangeable leaders of collectively migrating glioma abuse N-cadherin trafficking.

Collectively migrating cells consist of leaders and followers with different features. In this issue, Kim et al. (https://doi.org/10.1083/jcb.202401057) characterize the leader and follower cells in collective glioma migration and uncover important roles of YAP1/TAZ-mediated regulation of N-cadherin in the leader cells.

Multimodal decoding of human liver regeneration

The liver has a unique ability to regenerate1,2; however, in the setting of acute liver failure (ALF), this regenerative capacity is often overwhelmed, leaving emergency liver transplantation as the only curative option3–5. Here, to advance understanding of human liver regeneration, we use paired single-nucleus RNA sequencing combined with spatial profiling of healthy and ALF explant human livers to generate a single-cell, pan-lineage atlas of human liver regeneration. We uncover a novel ANXA2+ migratory hepatocyte subpopulation, which emerges during human liver regeneration, and a corollary subpopulation in a mouse model of acetaminophen (APAP)-induced liver regeneration. Interrogation of necrotic wound closure and hepatocyte proliferation across multiple timepoints following APAP-induced liver injury in mice demonstrates that wound closure precedes hepatocyte proliferation. Four-dimensional intravital imaging of APAP-induced mouse liver injury identifies motile hepatocytes at the edge of the necrotic area, enabling collective migration of the hepatocyte sheet to effect wound closure. Depletion of hepatocyte ANXA2 reduces hepatocyte growth factor-induced human and mouse hepatocyte migration in vitro, and abrogates necrotic wound closure following APAP-induced mouse liver injury. Together, our work dissects unanticipated aspects of liver regeneration, demonstrating an uncoupling of wound closure and hepatocyte proliferation and uncovering a novel migratory hepatocyte subpopulation that mediates wound closure following liver injury. Therapies designed to promote rapid reconstitution of normal hepatic microarchitecture and reparation of the gut–liver barrier may advance new areas of therapeutic discovery in regenerative medicine.

Dynamic cell photo-manipulation technology for the molecular and mechanical regulation analyses of collective cell migration

Collective cell migration is an essential biological process. Migration behaviors of multiple cellular units depend on the mechanical and chemical properties of their scaffolds and the geometry of the cells. However, the mechanisms by which these properties synergistically regulate the collective cell characteristics remain unknown. A robust method is required to analyze collective cell migration. Therefore, in this study, we developed a new method for collective cell migration analysis using defined chemical, mechanical, and geometrical properties. Our method is based on a poly(acrylic acid) hydrogel, whose surface is functionalized with photocleavable poly(ethylene glycol) and a cell-adhesive peptide. By controlling the UV irradiation of the photoactivatable hydrogel, we created geometrically controlled cellular clusters and induced collective migration. Furthermore, chemical and mechanical cues exposed to cell clusters were manipulated depending on the surface density of the cell-adhesive peptide and crosslinking density of the hydrogel. As a proof of concept, we also demonstrated that the collective migration of epithelial cells was synergistically regulated by the chemical and mechanical properties of the scaffold. Our results suggest the new photoactivatable substrate as a promising tool for advanced molecular and mechanobiological analyses of collective cell migration.

Plastic instability of annular crystalline membrane in circular confinement.

Understanding the mechanical instabilities of two-dimensional membranes has strong connection to the subjects of structure instabilities, morphology control, and materials failures. In this work, we investigate the plastic mechanism developed in the annular crystalline membrane system for adapting to the shrinking space, which is caused by the controllable gradual expansion of the inner boundary. In the process of plastic deformation, we find the continuous generation of dislocations at the inner boundary and their collective migration to the outer boundary; this neat dynamic scenario of dislocation current captures the complicated reorganization process of the particles. We also reveal the characteristic vortex structure arising from the interplay of topological defects and the displacement field. These results may find applications in the precise control of structural instabilities in packings of particulate matter and covalently bonded systems.

Plasmid partitioning driven by collective migration of ParA between nucleoid lobes

The ParABS system is crucial for the faithful segregation and inheritance of many bacterial chromosomes and low-copy-number plasmids. However, despite extensive research, the spatiotemporal dynamics of the ATPase ParA and its connection to the dynamics and positioning of the ParB-coated cargo have remained unclear. In this study, we utilize high-throughput imaging, quantitative data analysis, and computational modeling to explore the in vivo dynamics of ParA and its interaction with ParB-coated plasmids and the nucleoid. As previously observed, we find that F-plasmid ParA undergoes collective migrations ("flips") between cell halves multiple times per cell cycle. We reveal that a constricting nucleoid is required for these migrations and that they are triggered by a plasmid crossing into the cell half with greater ParA. Using simulations, we show that these dynamics can be explained by the combination of nucleoid constriction and cooperative ParA binding to the DNA, in line with the behavior of other ParA proteins. We further show that these ParA flips act to equally partition plasmids between the two lobes of the constricted nucleoid and are therefore important for plasmid stability, especially in fast growth conditions for which the nucleoid constricts early in the cell cycle. Overall, our work identifies a second mode of action of the ParABS system and deepens our understanding of how this important segregation system functions.

DLC1 promotes mechanotransductive feedback for YAP via RhoGAP-mediated focal adhesion turnover.

Angiogenesis is a tightly controlled dynamic process demanding a delicate equilibrium between pro-angiogenic signals and factors that promote vascular stability. The spatiotemporal activation of the transcriptional co-factors YAP (herein referring to YAP1) and TAZ (also known WWTR1), collectively denoted YAP/TAZ, is crucial to allow for efficient collective endothelial migration in angiogenesis. The focal adhesion protein deleted-in-liver-cancer-1 (DLC1) was recently described as a transcriptional downstream target of YAP/TAZ in endothelial cells. In this study, we uncover a negative feedback loop between DLC1 expression and YAP activity during collective migration and sprouting angiogenesis. In particular, our study demonstrates that signaling via the RhoGAP domain of DLC1 reduces nuclear localization of YAP and its transcriptional activity. Moreover, the RhoGAP activity of DLC1 is essential for YAP-mediated cellular processes, including the regulation of focal adhesion turnover, traction forces, and sprouting angiogenesis. We show that DLC1 restricts intracellular cytoskeletal tension by inhibiting Rho signaling at the basal adhesion plane, consequently reducing nuclear YAP localization. Collectively, these findings underscore the significance of DLC1 expression levels and its function in mitigating intracellular tension as a pivotal mechanotransductive feedback mechanism that finely tunes YAP activity throughout the process of sprouting angiogenesis.

N-cadherin directs the collective Schwann cell migration required for nerve regeneration through Slit2/3 mediated contact inhibition of locomotion.

Collective cell migration is fundamental for the development of organisms and in the adult, for tissue regeneration and in pathological conditions such as cancer. Migration as a coherent group requires the maintenance of cell-cell interactions, while contact inhibition of locomotion (CIL), a local repulsive force, can propel the group forward. Here we show that the cell-cell interaction molecule, N-cadherin, regulates both adhesion and repulsion processes during rat Schwann cell (SC) collective migration, which is required for peripheral nerve regeneration. However, distinct from its role in cell-cell adhesion, the repulsion process is independent of N-cadherin trans-homodimerisation and the associated adherens junction complex. Rather, the extracellular domain of N-cadherin is required to present the repulsive Slit2/Slit3 signal at the cell-surface. Inhibiting Slit2/Slit3 signalling inhibits CIL and subsequently collective Schwann cell migration, resulting in adherent, nonmigratory cell clusters. Moreover, analysis of ex vivo explants from mice following sciatic nerve injury showed that inhibition of Slit2 decreased Schwann cell collective migration and increased clustering of Schwann cells within the nerve bridge. These findings provide insight into how opposing signals can mediate collective cell migration and how CIL pathways are promising targets for inhibiting pathological cell migration.

PIEZO1 regulates leader cell formation and cellular coordination during collective keratinocyte migration.

The collective migration of keratinocytes during wound healing requires both the generation and transmission of mechanical forces for individual cellular locomotion and the coordination of movement across cells. Leader cells along the wound edge transmit mechanical and biochemical cues to ensuing follower cells, ensuring their coordinated direction of migration across multiple cells. Despite the observed importance of mechanical cues in leader cell formation and in controlling coordinated directionality of cell migration, the underlying biophysical mechanisms remain elusive. The mechanically-activated ion channel PIEZO1 was recently identified to play an inhibitory role during the reepithelialization of wounds. Here, through an integrative experimental and mathematical modeling approach, we elucidate PIEZO1's contributions to collective migration. Time-lapse microscopy reveals that PIEZO1 activity inhibits leader cell formation at the wound edge. To probe the relationship between PIEZO1 activity, leader cell formation and inhibition of reepithelialization, we developed an integrative 2D continuum model of wound closure that links observations at the single cell and collective cell migration scales. Through numerical simulations and subsequent experimental validation, we found that coordinated directionality plays a key role during wound closure and is inhibited by upregulated PIEZO1 activity. We propose that PIEZO1-mediated retraction suppresses leader cell formation which inhibits coordinated directionality between cells during collective migration.