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Stock C. pH-regulated single cell migration. Pflugers Arch 2024; 476:639-658. [PMID: 38214759 PMCID: PMC11006768 DOI: 10.1007/s00424-024-02907-2] [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: 11/22/2023] [Revised: 12/21/2023] [Accepted: 01/02/2024] [Indexed: 01/13/2024]
Abstract
Over the last two decades, extra- and intracellular pH have emerged as fundamental regulators of cell motility. Fundamental physiological and pathological processes relying on appropriate cell migration, such as embryonic development, wound healing, and a proper immune defense on the one hand, and autoimmune diseases, metastatic cancer, and the progression of certain parasitic diseases on the other, depend on surrounding pH. In addition, migrating single cells create their own localized pH nanodomains at their surface and in the cytosol. By this means, the migrating cells locally modulate their adhesion to, and the re-arrangement and digestion of, the extracellular matrix. At the same time, the cytosolic nanodomains tune cytoskeletal dynamics along the direction of movement resulting in concerted lamellipodia protrusion and rear end retraction. Extracellular pH gradients as found in wounds, inflamed tissues, or the periphery of tumors stimulate directed cell migration, and long-term exposure to acidic conditions can engender a more migratory and invasive phenotype persisting for hours up to several generations of cells after they have left the acidic milieu. In the present review, the different variants of pH-dependent single cell migration are described. The underlying pH-dependent molecular mechanisms such as conformational changes of adhesion molecules, matrix protease activity, actin (de-)polymerization, and signaling events are explained, and molecular pH sensors stimulated by H+ signaling are presented.
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Affiliation(s)
- Christian Stock
- Department of Gastroenterology, Hepatology, Infectiology & Endocrinology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
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2
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Plazen L, Khadra A. Excitable dynamics in a molecularly-explicit model of cell motility: Mixed-mode oscillations and beyond. J Theor Biol 2023; 564:111450. [PMID: 36868346 DOI: 10.1016/j.jtbi.2023.111450] [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: 11/18/2022] [Revised: 02/11/2023] [Accepted: 02/23/2023] [Indexed: 03/05/2023]
Abstract
Mesenchymal cell motility is mainly regulated by two members of the Rho-family of GTPases, called Rac and Rho. The mutual inhibition exerted by these two proteins on each other's activation and the promotion of Rac activation by an adaptor protein called paxillin have been implicated in driving cellular polarization comprised of front (high active Rac) and back (high active Rho) during cell migration. Mathematical modeling of this regulatory network has previously shown that bistability is responsible for generating a spatiotemporal pattern underscoring cellular polarity called wave-pinning when diffusion is included. We previously developed a 6V reaction-diffusion model of this network to decipher the role of Rac, Rho and paxillin (along with other auxiliary proteins) in generating wave-pinning. In this study, we simplify this model through a series of steps into an excitable 3V ODE model comprised of one fast variable (the scaled concentration of active Rac), one slow variable (the maximum paxillin phosphorylation rate - turned into a variable) and a very slow variable (a recovery rate - also turned into a variable). We then explore, through slow-fast analysis, how excitability is manifested by showing that the model can exhibit relaxation oscillations (ROs) as well as mixed-mode oscillations (MMOs) whose underlying dynamics are consistent with a delayed Hopf bifurcation with a canard explosion. By reintroducing diffusion and the scaled concentration of inactive Rac into the model, we obtain a 4V PDE model that generates several unique spatiotemporal patterns that are relevant to cell motility. These patterns are then characterized and their impact on cell motility are explored by employing the cellular potts model (CPM). Our results reveal that wave pinning produces purely very directed motion in CPM, while MMOs allow for meandering and non-motile behaviors to occur. This highlights the role of MMOs as a potential mechanism for mesenchymal cell motility.
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Affiliation(s)
- Lucie Plazen
- Department of Mathematics and Statistics, McGill University, Montreal, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, Montreal, Canada.
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3
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Plazen L, Rahbani JA, Brown CM, Khadra A. Polarity and mixed-mode oscillations may underlie different patterns of cellular migration. Sci Rep 2023; 13:4223. [PMID: 36918704 PMCID: PMC10014943 DOI: 10.1038/s41598-023-31042-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 03/06/2023] [Indexed: 03/16/2023] Open
Abstract
In mesenchymal cell motility, several migration patterns have been observed, including directional, exploratory and stationary. Two key members of the Rho-family of GTPases, Rac and Rho, along with an adaptor protein called paxillin, have been particularly implicated in the formation of such migration patterns and in regulating adhesion dynamics. Together, they form a key regulatory network that involves the mutual inhibition exerted by Rac and Rho on each other and the promotion of Rac activation by phosphorylated paxillin. Although this interaction is sufficient in generating wave-pinning that underscores cellular polarization comprised of cellular front (high active Rac) and back (high active Rho), it remains unclear how they interact collectively to induce other modes of migration detected in Chinese hamster Ovary (CHO-K1) cells. We previously developed a six-variable (6V) reaction-diffusion model describing the interactions of these three proteins (in their active/phosphorylated and inactive/unphosphorylated forms) along with other auxiliary proteins, to decipher their role in generating wave-pinning. In this study, we explored, through computational modeling and image analysis, how differences in timescales within this molecular network can potentially produce the migration patterns in CHO-K1 cells and how switching between migration modes could occur. To do so, the 6V model was reduced to an excitable 4V spatiotemporal model possessing three different timescales. The model produced not only wave-pinning in the presence of diffusion, but also mixed-mode oscillations (MMOs) and relaxation oscillations (ROs). Implementing the model using the Cellular Potts Model (CPM) produced outcomes in which protrusions in the cell membrane changed Rac-Rho localization, resulting in membrane oscillations and fast directionality variations similar to those observed experimentally in CHO-K1 cells. The latter was assessed by comparing the migration patterns of experimental with CPM cells using four metrics: instantaneous cell speed, exponent of mean-square displacement ([Formula: see text]-value), directionality ratio and protrusion rate. Variations in migration patterns induced by mutating paxillin's serine 273 residue were also captured by the model and detected by a machine classifier, revealing that this mutation alters the dynamics of the system from MMOs to ROs or nonoscillatory behaviour through variation in the scaled concentration of an active form of an adhesion protein called p21-Activated Kinase 1 (PAK). These results thus suggest that MMOs and adhesion dynamics are the key mechanisms regulating CHO-K1 cell motility.
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Affiliation(s)
- Lucie Plazen
- Department of Mathematics and Statistics, McGill University, Montreal, Canada
| | | | - Claire M Brown
- Department of Physiology, McGill University, Montreal, Canada
- Advanced BioImaging Facility (ABIF), McGill University, Montreal, QC, Canada
- Cell Information Systems, McGill University, Montreal, QC, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, Montreal, Canada.
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Campanale JP, Mondo JA, Montell DJ. A Scribble/Cdep/Rac pathway controls follower-cell crawling and cluster cohesion during collective border-cell migration. Dev Cell 2022; 57:2483-2496.e4. [PMID: 36347240 PMCID: PMC9725179 DOI: 10.1016/j.devcel.2022.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 08/10/2022] [Accepted: 10/12/2022] [Indexed: 11/09/2022]
Abstract
Collective cell movements drive normal development and metastasis. Drosophila border cells move as a cluster of 6-10 cells, where the role of the Rac GTPase in migration was first established. In border cells, as in most migratory cells, Rac stimulates leading-edge protrusion. Upstream Rac regulators in leaders have been identified; however, the regulation and function of Rac in follower border cells is unknown. Here, we show that all border cells require Rac, which promotes follower-cell motility and is important for cluster compactness and movement. We identify a Rac guanine nucleotide exchange factor, Cdep, which also regulates follower-cell movement and cluster cohesion. Scribble, Discs large, and Lethal giant larvae localize Cdep basolaterally and share phenotypes with Cdep. Relocalization of Cdep::GFP partially rescues Scribble knockdown, suggesting that Cdep is a major downstream effector of basolateral proteins. Thus, a Scrib/Cdep/Rac pathway promotes cell crawling and coordinated, collective migration in vivo.
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Affiliation(s)
- Joseph P Campanale
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - James A Mondo
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Denise J Montell
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
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5
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Abstract
Cell migration, a crucial step in numerous biological processes, is tightly regulated in space and time. Cells employ Rho GTPases, primarily Rho, Rac, and Cdc42, to regulate their motility. Like other small G proteins, Rho GTPases function as biomolecular switches in regulating cell migration by operating between GDP bound 'OFF' and GTP bound 'ON' states. Guanine nucleotide exchange factors (GEFs) catalyse the shuttling of GTPases from OFF to ON state. G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors that are involved in many signalling phenomena including cell survival and cell migration events. In this review, we summarize signalling mechanisms, involving GPCRs, leading to the activation of RhoGEFs. GPCRs exhibit diverse GEF activation modes that include the interaction of heterotrimeric G protein subunits with different domains of GEFs, phosphorylation, protein-protein interaction, protein-lipid interaction, and/or a combination of these processes.
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Affiliation(s)
- Aishwarya Omble
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune, India,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Kiran Kulkarni
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune, India,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India,CONTACT Kiran Kulkarni Academy of Scientific and Innovative Research (Acsir), Ghaziabad 201002, India
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6
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Orduña-Castillo LB, Del-Río-Robles JE, García-Jiménez I, Zavala-Barrera C, Beltrán-Navarro YM, Hidalgo-Moyle JJ, Ramírez-Rangel I, Hernández-Bedolla MA, Reyes-Ibarra AP, Valadez-Sánchez M, Vázquez-Prado J, Reyes-Cruz G. Calcium sensing receptor stimulates breast cancer cell migration via the Gβγ-AKT-mTORC2 signaling pathway. J Cell Commun Signal 2021; 16:239-252. [PMID: 34854057 DOI: 10.1007/s12079-021-00662-y] [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: 01/31/2021] [Accepted: 11/21/2021] [Indexed: 10/19/2022] Open
Abstract
Calcium sensing receptor, a pleiotropic G protein coupled receptor, activates secretory pathways in cancer cells and putatively exacerbates their metastatic behavior. Here, we show that various CaSR mutants, identified in breast cancer patients, differ in their ability to stimulate Rac, a small Rho GTPase linked to cytoskeletal reorganization and cell protrusion, but are similarly active on the mitogenic ERK pathway. To investigate how CaSR activates Rac and drives cell migration, we used invasive MDA-MB-231 breast cancer cells. We revealed, by pharmacological and knockdown strategies, that CaSR activates Rac and cell migration via the Gβγ-PI3K-mTORC2 pathway. These findings further support current efforts to validate CaSR as a relevant therapeutic target in metastatic cancer.
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Affiliation(s)
- Lennis Beatriz Orduña-Castillo
- Department of Cell Biology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360, Mexico City, Mexico
| | - Jorge Eduardo Del-Río-Robles
- Department of Cell Biology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360, Mexico City, Mexico
| | - Irving García-Jiménez
- Department of Cell Biology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360, Mexico City, Mexico
| | - César Zavala-Barrera
- Department of Cell Biology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360, Mexico City, Mexico
| | | | - Joseline Janai Hidalgo-Moyle
- Department of Cell Biology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360, Mexico City, Mexico
| | | | - Marco A Hernández-Bedolla
- Department of Cell Biology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360, Mexico City, Mexico.,Licenciatura en Enfermería, Escuela Superior de Huejutla, Universidad Autónoma del Estado de Hidalgo, Huejutla de Reyes, Hidalgo, México
| | - Alma P Reyes-Ibarra
- Department of Cell Biology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360, Mexico City, Mexico
| | - Margarita Valadez-Sánchez
- Department of Cell Biology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360, Mexico City, Mexico
| | | | - Guadalupe Reyes-Cruz
- Department of Cell Biology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360, Mexico City, Mexico.
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7
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MacKay L, Lehman E, Khadra A. Deciphering the dynamics of lamellipodium in a fish keratocytes model. J Theor Biol 2020; 512:110534. [PMID: 33181178 DOI: 10.1016/j.jtbi.2020.110534] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 11/15/2022]
Abstract
Motile cells depend on an intricate network of feedback loops that are essential in driving cell movement. Integrin-based focal adhesions (FAs) along with actin are the two key factors that mediate such motile behaviour. Together, they generate excitable dynamics that are essential for forming protrusions at the leading edge of the cell and, in certain cases, traveling waves along the membrane. A partial differential equation (PDE) model of a self-organizing lamellipodium in crawling keratocytes has been previously developed to understand how the three spatiotemporal patterns of activity observed in such cells, namely, stalling, waving and smooth motility, are produced. The model consisted of three key variables: the density of barbed actin filaments, newly formed FAs called nascent adhesions (NAs) and VASP, an anti-capping protein that gets sequestered by NAs during maturation. Using parameter sweeping techniques, the distinct regimes of behaviour associated with the three activity patterns were identified. In this study, we convert the PDE model into an ordinary differential equation (ODE) model to examine its excitability properties and determine all the patterns of activity exhibited by this system. Our results reveal that there are two additional regimes not previously identified, including bistability and oscillatory-like type IV excitability (generated by three steady states and their manifolds, rather than limit cycles). These regimes are also present in the PDE model. Applying slow-fast analysis on the ODE model shows that it exhibits a canard explosion through a folded-saddle and that rough motility seen in keratocytes is likely due to noise-dependent motility governed by dynamics near the interface of bistability and type IV excitability. The two parameter bifurcation suggests that the increase in the proportion of rough motion is due to a shift in activity towards the bistable and type IV excitable regimes induced by a decrease in NA maturation rate. Our results thus provide important insight into how microscopic mechanical effects are integrated to produce the observed modes of motility.
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Affiliation(s)
- Laurent MacKay
- Department of Physiology, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, QC H3G 1Y6, Canada.
| | | | - Anmar Khadra
- Department of Physiology, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, QC H3G 1Y6, Canada.
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8
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Bolado-Carrancio A, Rukhlenko OS, Nikonova E, Tsyganov MA, Wheeler A, Garcia-Munoz A, Kolch W, von Kriegsheim A, Kholodenko BN. Periodic propagating waves coordinate RhoGTPase network dynamics at the leading and trailing edges during cell migration. eLife 2020; 9:58165. [PMID: 32705984 PMCID: PMC7380942 DOI: 10.7554/elife.58165] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 07/02/2020] [Indexed: 12/27/2022] Open
Abstract
Migrating cells need to coordinate distinct leading and trailing edge dynamics but the underlying mechanisms are unclear. Here, we combine experiments and mathematical modeling to elaborate the minimal autonomous biochemical machinery necessary and sufficient for this dynamic coordination and cell movement. RhoA activates Rac1 via DIA and inhibits Rac1 via ROCK, while Rac1 inhibits RhoA through PAK. Our data suggest that in motile, polarized cells, RhoA–ROCK interactions prevail at the rear, whereas RhoA-DIA interactions dominate at the front where Rac1/Rho oscillations drive protrusions and retractions. At the rear, high RhoA and low Rac1 activities are maintained until a wave of oscillatory GTPase activities from the cell front reaches the rear, inducing transient GTPase oscillations and RhoA activity spikes. After the rear retracts, the initial GTPase pattern resumes. Our findings show how periodic, propagating GTPase waves coordinate distinct GTPase patterns at the leading and trailing edge dynamics in moving cells.
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Affiliation(s)
- Alfonso Bolado-Carrancio
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Oleksii S Rukhlenko
- Systems Biology Ireland, School of Medicine and Medical Science, University College Dublin, Belfield, Ireland
| | - Elena Nikonova
- Systems Biology Ireland, School of Medicine and Medical Science, University College Dublin, Belfield, Ireland
| | - Mikhail A Tsyganov
- Systems Biology Ireland, School of Medicine and Medical Science, University College Dublin, Belfield, Ireland.,Institute of Theoretical and Experimental Biophysics, Pushchino, Russian Federation
| | - Anne Wheeler
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Amaya Garcia-Munoz
- Systems Biology Ireland, School of Medicine and Medical Science, University College Dublin, Belfield, Ireland
| | - Walter Kolch
- Systems Biology Ireland, School of Medicine and Medical Science, University College Dublin, Belfield, Ireland.,Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Ireland
| | - Alex von Kriegsheim
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom.,Systems Biology Ireland, School of Medicine and Medical Science, University College Dublin, Belfield, Ireland
| | - Boris N Kholodenko
- Systems Biology Ireland, School of Medicine and Medical Science, University College Dublin, Belfield, Ireland.,Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Ireland.,Department of Pharmacology, Yale University School of Medicine, New Haven, United States
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9
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MacKay L, Khadra A. The bioenergetics of integrin-based adhesion, from single molecule dynamics to stability of macromolecular complexes. Comput Struct Biotechnol J 2020; 18:393-416. [PMID: 32128069 PMCID: PMC7044673 DOI: 10.1016/j.csbj.2020.02.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 12/22/2022] Open
Abstract
The forces actively generated by motile cells must be transmitted to their environment in a spatiotemporally regulated manner, in order to produce directional cellular motion. This task is accomplished through integrin-based adhesions, large macromolecular complexes that link the actin-cytoskelton inside the cell to its external environment. Despite their relatively large size, adhesions exhibit rapid dynamics, switching between assembly and disassembly in response to chemical and mechanical cues exerted by cytoplasmic biochemical signals, and intracellular/extracellular forces, respectively. While in material science, force typically disrupts adhesive contact, in this biological system, force has a more nuanced effect, capable of causing assembly or disassembly. This initially puzzled experimentalists and theorists alike, but investigation into the mechanisms regulating adhesion dynamics have progressively elucidated the origin of these phenomena. This review provides an overview of recent studies focused on the theoretical understanding of adhesion assembly and disassembly as well as the experimental studies that motivated them. We first concentrate on the kinetics of integrin receptors, which exhibit a complex response to force, and then investigate how this response manifests itself in macromolecular adhesion complexes. We then turn our attention to studies of adhesion plaque dynamics that link integrins to the actin-cytoskeleton, and explain how force can influence the assembly/disassembly of these macromolecular structure. Subsequently, we analyze the effect of force on integrins populations across lengthscales larger than single adhesions. Finally, we cover some theoretical studies that have considered both integrins and the adhesion plaque and discuss some potential future avenues of research.
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Affiliation(s)
- Laurent MacKay
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada
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10
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Lyda JK, Tan ZL, Rajah A, Momi A, Mackay L, Brown CM, Khadra A. Rac activation is key to cell motility and directionality: An experimental and modelling investigation. Comput Struct Biotechnol J 2019; 17:1436-1452. [PMID: 31871589 PMCID: PMC6906685 DOI: 10.1016/j.csbj.2019.10.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 01/04/2023] Open
Abstract
Cell migration is a tightly-regulated process that involves protein gradients formed by the Rho family of GTPases, including Rho and Rac. The front (rear) of cells is generally characterized by higher active Rac (Rho) and lower active Rho (Rac) concentrations. Protein clusters, called adhesions, that anchor cells to their external environment have been shown to be dynamic and small (stable and large) at the cell front (rear), forming the force-transmission points necessary for persistent movement. Differences in adhesion sizes and dynamics have been linked to gradients in Rac and Rho activity. Here, we study the effects of Rac activation and gradients in Rac and Rho concentrations and activities on cellular polarity and adhesion size using mathematical and experimental approaches. The former is accomplished by expanding an existing reaction-diffusion model to a 2D domain utilizing stochastic dynamics. The model revealed that a hysteresis between the induced/uninduced states (corresponding to higher/lower Rac concentrations, respectively) along with Rac and Rho activation gradients, generated by chemical cues, were vital for forming polarity. Experimentally, the induced state was generated by increasing the cellular βPIX (a Rac-GEF) level and/or decreasing ROCK (a Rac-GAP effector protein) activity with Y-27632 (a ROCK-inhibitor). In agreement with the simulations, our results showed that cells with elevated RacGTP migrated faster, indicating more robust cellular polarization. However, the directionality of cells was not changed significantly, suggesting that external and/or internal physical or chemical cues were needed. Complementing the faster migration observed, adhesions were smaller, generating the phenotype expected with the induced state.
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Affiliation(s)
- Jessica K Lyda
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Zhang L Tan
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Abira Rajah
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Asheesh Momi
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Laurent Mackay
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Claire M Brown
- Department of Physiology, McGill University, Montréal, Québec, Canada.,Advanced BioImaging Facility (ABIF), McGill University, Montréal, Québec, Canada.,Cell Information Systems, McGill University, Montréal, Québec, Canada.,Department of Anatomy and Cell Biology, McGill University, Montréal, Québec, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, Montréal, Québec, Canada
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