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Kippenberger S, Pipa G, Steinhorst K, Zöller N, Kleemann J, Özistanbullu D, Kaufmann R, Scheller B. Learning in the Single-Cell Organism Physarum polycephalum: Effect of Propofol. Int J Mol Sci 2023; 24:ijms24076287. [PMID: 37047260 PMCID: PMC10094176 DOI: 10.3390/ijms24076287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/17/2023] [Accepted: 03/23/2023] [Indexed: 03/29/2023] Open
Abstract
Propofol belongs to a class of molecules that are known to block learning and memory in mammals, including rodents and humans. Interestingly, learning and memory are not tied to the presence of a nervous system. There are several lines of evidence indicating that single-celled organisms also have the capacity for learning and memory which may be considered as basal intelligence. Here, we introduce a new experimental model for testing the learning ability of Physarum polycephalum, a model organism frequently used to study single-celled “intelligence”. In this study, the impact of propofol on Physarum’s “intelligence” was tested. The model consists of a labyrinth of subsequent bifurcations in which food (oat flakes soaked with coconut oil-derived medium chain triglycerides [MCT] and soybean oil-derived long chain triglycerides [LCT]) or propofol in MCT/LCT) is placed in one of each Y-branch. In this setting, it was tested whether Physarum memorized the rewarding branch. We saw that Physarum was a quick learner when capturing the first bifurcations of the maze; thereafter, the effect decreased, perhaps due to reaching a state of satiety. In contrast, when oat flakes were soaked with propofol, Physarum’s preference for oat flakes declined significantly. Several possible actions, including the blocking of gamma-aminobutyric acid (GABA) receptor signaling, are suggested to account for this behavior, many of which can be tested in our new model.
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2
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Liu H, Liu S, Xiao Y, Song W, Li H, Ho LWC, Shen Z, Choi CHJ. A pH-Reversible Fluorescent Probe for in Situ Imaging of Extracellular Vesicles and Their Secretion from Living Cells. NANO LETTERS 2021; 21:9224-9232. [PMID: 34724785 DOI: 10.1021/acs.nanolett.1c03110] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Our knowledge in how extracellular vesicles (EVs) are secreted from cells remains inadequate due to the limited technologies available for visualizing them in situ. We report a pH-reversible boron dipyrromethene (BODIPY) fluorescent probe for confocal imaging of EVs secreted from living cells without inducing severe cytotoxicity. This probe predominantly assumes a non-fluorescent leuco-BODIPY form under basic conditions, but it gradually switches to its fluorescent parent BODIPY form upon acidification; such pH transition empowers the imaging of acidic EVs (such as CD81-enriched exosomes and extracellular multivesicular bodies) in weakly basic culture medium and intracellular acidic precursor EVs in weakly basic cytoplasm, with minimal false positive signals frequently encountered for "always-on" dyes. Joint application of this probe with plasmid transfection reveals the secretion of some EVs from cellular pseudopodia via microtubule trackways. This probe may provide mechanistic insights into the extracellular transport of EVs and support the development of EV-based nanomedicines.
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Affiliation(s)
- Hanzhuang Liu
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Shaorui Liu
- Department of Surgery, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Yu Xiao
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Wenting Song
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Huize Li
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Lok Wai Cola Ho
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Zhen Shen
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Chung Hang Jonathan Choi
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
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3
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Vallverdú J, Castro O, Mayne R, Talanov M, Levin M, Baluška F, Gunji Y, Dussutour A, Zenil H, Adamatzky A. Slime mould: The fundamental mechanisms of biological cognition. Biosystems 2018; 165:57-70. [DOI: 10.1016/j.biosystems.2017.12.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 12/18/2017] [Accepted: 12/20/2017] [Indexed: 01/27/2023]
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4
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Álvarez-González B, Zhang S, Gómez-González M, Meili R, Firtel RA, Lasheras JC, Del Álamo JC. Two-Layer Elastographic 3-D Traction Force Microscopy. Sci Rep 2017; 7:39315. [PMID: 28074837 PMCID: PMC5225457 DOI: 10.1038/srep39315] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 11/15/2016] [Indexed: 01/16/2023] Open
Abstract
Cellular traction force microscopy (TFM) requires knowledge of the mechanical properties of the substratum where the cells adhere to calculate cell-generated forces from measurements of substratum deformation. Polymer-based hydrogels are broadly used for TFM due to their linearly elastic behavior in the range of measured deformations. However, the calculated stresses, particularly their spatial patterns, can be highly sensitive to the substratum's Poisson's ratio. We present two-layer elastographic TFM (2LETFM), a method that allows for simultaneously measuring the Poisson's ratio of the substratum while also determining the cell-generated forces. The new method exploits the analytical solution of the elastostatic equation and deformation measurements from two layers of the substratum. We perform an in silico analysis of 2LETFM concluding that this technique is robust with respect to TFM experimental parameters, and remains accurate even for noisy measurement data. We also provide experimental proof of principle of 2LETFM by simultaneously measuring the stresses exerted by migrating Physarum amoeboae on the surface of polyacrylamide substrata, and the Poisson's ratio of the substrata. The 2LETFM method could be generalized to concurrently determine the mechanical properties and cell-generated forces in more physiologically relevant extracellular environments, opening new possibilities to study cell-matrix interactions.
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Affiliation(s)
- Begoña Álvarez-González
- Division of Cell and Developmental Biology, University of California, San Diego.,Department of Mechanical and Aerospace Engineeing, University of California, San Diego
| | - Shun Zhang
- Department of Mechanical and Aerospace Engineeing, University of California, San Diego
| | - Manuel Gómez-González
- Department of Mechanical and Aerospace Engineeing, University of California, San Diego
| | - Ruedi Meili
- Division of Cell and Developmental Biology, University of California, San Diego.,Department of Mechanical and Aerospace Engineeing, University of California, San Diego
| | - Richard A Firtel
- Division of Cell and Developmental Biology, University of California, San Diego
| | - Juan C Lasheras
- Department of Mechanical and Aerospace Engineeing, University of California, San Diego.,Department of Bioengineering, University of California, San Diego.,Center for Medical Devices and Instrumentation, Institute for Engineering in Medicine, University of California, San Diego
| | - Juan C Del Álamo
- Department of Mechanical and Aerospace Engineeing, University of California, San Diego.,Center for Medical Devices and Instrumentation, Institute for Engineering in Medicine, University of California, San Diego
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5
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Ng IC, Pawijit P, Teo LY, Li H, Lee SY, Yu H. Kinectin-dependent ER transport supports the focal complex maturation required for chemotaxis in shallow gradients. J Cell Sci 2016; 129:2660-72. [PMID: 27221621 DOI: 10.1242/jcs.181768] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 05/19/2016] [Indexed: 01/09/2023] Open
Abstract
Chemotaxis in shallow gradients of chemoattractants is accomplished by preferential maintenance of protrusions oriented towards the chemoattractant; however, the mechanism of preferential maintenance is not known. Here, we test the hypothesis that kinectin-dependent endoplasmic reticulum (ER) transport supports focal complex maturation to preferentially maintain correctly oriented protrusions. We knocked down kinectin expression in MDA-MB-231 cells using small interfering RNA and observed that kinectin contributes to the directional bias, but not the speed, of cell migration. Kymograph analysis revealed that the extension of protrusions oriented towards the chemoattractant was not affected by kinectin knockdown, but that their maintenance was. Immunofluorescence staining and live-cell imaging demonstrated that kinectin transports ER preferentially to protrusions oriented towards the chemoattractant. ER then promotes the maturation of focal complexes into focal adhesions to maintain these protrusions for chemotaxis. Our results show that kinectin-dependent ER distribution can be localized by chemoattractants and provide a mechanism for biased protrusion choices during chemotaxis in shallow gradients of chemoattractants.
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Affiliation(s)
- Inn Chuan Ng
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Pornteera Pawijit
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Lee Ying Teo
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Huipeng Li
- Singapore-MIT Alliance, E4-04-10, 4 Engineering Drive 3, Singapore 117576, Singapore
| | - Shu Ying Lee
- Confocal Microscopy Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117549, Singapore
| | - Hanry Yu
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore Singapore-MIT Alliance, E4-04-10, 4 Engineering Drive 3, Singapore 117576, Singapore Confocal Microscopy Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117549, Singapore Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore Institute of Bioengineering and Nanotechnology, A*STAR, Singapore 138669, Singapore Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, #10-01 CREATE Tower, Singapore 138602, Singapore Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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6
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Van Haastert PJM. A stochastic model for chemotaxis based on the ordered extension of pseudopods. Biophys J 2011; 99:3345-54. [PMID: 21081083 DOI: 10.1016/j.bpj.2010.09.042] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 09/10/2010] [Accepted: 09/13/2010] [Indexed: 01/25/2023] Open
Abstract
Many amoeboid cells move by extending pseudopods. Here I present a new stochastic model for chemotaxis that is based on pseudopod extensions by Dictyostelium cells. In the absence of external cues, pseudopod extension is highly ordered with two types of pseudopods: de novo formation of a pseudopod at the cell body in random directions, and alternating right/left splitting of an existing pseudopod that leads to a persistent zig-zag trajectory. We measured the directional probabilities of the extension of splitting and de novo pseudopods in chemoattractant gradients with different steepness. Very shallow cAMP gradients can bias the direction of splitting pseudopods, but the bias is not perfect. Orientation of de novo pseudopods require much steeper cAMP gradients and can be more precise. These measured probabilities of pseudopod directions were used to obtain an analytical model for chemotaxis of cell populations. Measured chemotaxis of wild-type cells and mutants with specific defects in these stochastic pseudopod properties are similar to predictions of the model. These results show that combining splitting and de novo pseudopods is a very effective way for cells to obtain very high sensitivity to stable gradient and still be responsive to changes in the direction of the gradient.
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7
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Irimia D, Balázsi G, Agrawal N, Toner M. Adaptive-control model for neutrophil orientation in the direction of chemical gradients. Biophys J 2009; 96:3897-916. [PMID: 19450463 DOI: 10.1016/j.bpj.2008.12.3967] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 12/09/2008] [Accepted: 12/23/2008] [Indexed: 10/20/2022] Open
Abstract
Neutrophils have a remarkable ability to detect the direction of chemoattractant gradients and move directionally in response to bacterial infections and tissue injuries. For their role in health and disease, neutrophils have been extensively studied, and many of the molecules involved in the signaling mechanisms of gradient detection and chemotaxis have been identified. However, the cellular-scale mechanisms of gradient sensing and directional neutrophil migration have been more elusive, and existent models provide only limited insight into these processes. Here, we propose a what we believe is a novel adaptive-control model for the initiation of cell polarization in response to gradients. In this model, the neutrophils first sample the environment by extending protrusions in random directions and subsequently adapt their sensitivity depending on localized, temporal changes in stimulation levels. Our results suggest that microtubules may play a critical role in integrating all the sensing events from the cellular periphery through their redistribution inside the neutrophils, and may also be involved in modulating local signaling. An unexpected finding was that model neutrophils exhibit significant randomness in timing and directionality of activation, comparable to our experimental observations in microfluidic devices. Moreover, their responses are robust against alterations of the rate and amplitude of the signaling reactions, and for a broad range in chemoattractant concentrations and spatial gradients.
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Affiliation(s)
- Daniel Irimia
- BioMEMS Resource Center, Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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8
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Rothmeier AS, Ischenko I, Joore J, Garczarczyk D, Fürst R, Bruns CJ, Vollmar AM, Zahler S. Investigation of the marine compound spongistatin 1 links the inhibition of PKCalpha translocation to nonmitotic effects of tubulin antagonism in angiogenesis. FASEB J 2008; 23:1127-37. [PMID: 19056838 DOI: 10.1096/fj.08-117127] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aims of the study were to meet the demand of new tubulin antagonists with fewer side effects by characterizing the antiangiogenic properties of the experimental compound spongistatin 1, and to elucidate nonmitotic mechanisms by which tubulin antagonists inhibit angiogenesis. Although tubulin-inhibiting drugs and their antiangiogenic properties have been investigated for a long time, surprisingly little is known about their underlying mechanisms of action. Antiangiogenic effects of spongistatin 1 were investigated in endothelial cells in vitro, including functional cell-based assays, live-cell imaging, and a kinome array, and in the mouse cornea pocket assay in vivo. Spongistatin 1 inhibited angiogenesis at nanomolar concentrations (IC(50): cytotoxicity>50 nM, proliferation 100 pM, migration 1.0 nM, tube formation 1.0 nM, chemotaxis 1.0 nM, aortic ring sprouting 500 pM, neovascularization in vivo 10 microg/kg). Further, a kinome array and validating data showed that spongistatin 1 inhibits the phosphorylation activity of protein kinase Calpha (PKCalpha), an essential kinase in angiogenesis, and its translocation to the membrane. Thus, we conclude that PKCalpha might be an important target for the antiangiogenic effects of tubulin antagonism. In addition, the data from the kinase array suggest that different tubulin antagonists might have individual intracellular actions.
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Affiliation(s)
- Andrea S Rothmeier
- Department of Pharmacy, Center for Drug Research, University of Munich, Munich, Germany
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9
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Baudoin JP, Alvarez C, Gaspar P, Métin C. Nocodazole-induced changes in microtubule dynamics impair the morphology and directionality of migrating medial ganglionic eminence cells. Dev Neurosci 2008; 30:132-43. [PMID: 18075261 DOI: 10.1159/000109858] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Accepted: 04/11/2007] [Indexed: 11/19/2022] Open
Abstract
We have shown previously that actomyosin contractility plays an important role in controlling nuclear movements in future interneurons born in the medial ganglionic eminence (MGE) [Bellion et al.: J Neurosci 2005;25:5691-5699]. Because microtubules are known to control the structural and motile properties of migrating neurons, we asked whether alterations in the dynamic instability of microtubules would impair MGE cell migration. Migration was analyzed in flat cocultures in which green-fluorescent-protein-expressing MGE cells migrate on cortical cells from their explant of origin. A low (100 nM) concentration of nocodazole shortened the leading process of MGE cells that nevertheless continued to migrate at the same rate but frequently changed their direction of migration relative to control cells. MGE cells treated with a higher (1 muM) concentration of nocodazole that strongly destabilized microtubules took on multipolar morphology. They extended thin and labile processes. MGE cells no longer exhibited directional migration and migration velocity slowed 2-fold. These results suggest that microtubule stability is crucial for maintaining polarity and controlling the directional migration of MGE cells, whereas additional mechanisms are required to control cell motility.
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10
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Abstract
We have developed a top-down, rule-based mathematical model to explore the basic principles that coordinate mechanochemical events during animal cell migration, particularly the local-stimulation-global-inhibition model suggested originally for chemotaxis. Cells were modeled as a shape machine that protrudes or retracts in response to a combination of local protrusion and global retraction signals. Using an optimization algorithm to identify parameters that generate specific shapes and migration patterns, we show that the mechanism of local stimulation global inhibition can readily account for the behavior of Dictyostelium under a large collection of conditions. Within this collection, some parameters showed strong correlation, indicating that a normal phenotype may be maintained by complementation among functional modules. In addition, comparison of parameters for control and nocodazole-treated Dictyostelium identified the most prominent effect of microtubules as regulating the rates of retraction and protrusion signal decay, and the extent of global inhibition. Other changes in parameters can lead to profound transformations from amoeboid cells into cells mimicking keratocytes, neurons, or fibroblasts. Thus, a simple circuit of local stimulation-global inhibition can account for a wide range of cell behaviors. A similar top-down approach may be applied to other complex problems and combined with molecular manipulations to define specific protein functions.
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11
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Pickup ZL, Pickup R, Parry JD. A comparison of the growth and starvation responses of Acanthamoeba castellanii and Hartmannella vermiformis in the presence of suspended and attached Escherichia coli K12. FEMS Microbiol Ecol 2007; 59:556-63. [PMID: 17059479 DOI: 10.1111/j.1574-6941.2006.00224.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The growth and starvation responses of Acanthamoeba castellanii and Hartmannella vermiformis were investigated in the presence and absence of Escherichia coli on an agar surface or within shaken suspensions. The amoebae perceived all the suspended systems to be unfavourable for growth, despite being challenged with high levels of prey, and as a consequence they exhibited a starvation response. However, the response differed between species, with A. castellanii producing characteristic cysts and H. vermiformis producing round bodies. These amoebic forms were reactivated into feeding trophozoites in the presence of bacterial aggregates, which formed in the suspended systems after 68 h of incubation. In contrast, both species of amoebae grew well in the presence of attached E. coli at a concentration of 1 x 10(6) cells cm(-2) of agar and yielded specific growth rates of c. 0.04 h(-1). Starvation responses were induced at the end of the growth phase, and these were equivalent to those recorded in the suspended systems. We conclude that, when suspended, amoebae in the 'floating form' cannot feed effectively on suspended prey, and hence the starvation response is initiated. Thus the majority of amoebic feeding is via trophozoite grazing of attached bacterial prey.
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Affiliation(s)
- Zoë L Pickup
- Department of Biological Sciences, The Lancaster Environment Centre, Lancaster University, Lancaster, UK
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12
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Brahmbhatt AA, Klemke RL. ERK and RhoA differentially regulate pseudopodia growth and retraction during chemotaxis. J Biol Chem 2003; 278:13016-25. [PMID: 12571246 DOI: 10.1074/jbc.m211873200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Nonmotile cells extend and retract pseudopodia-like structures in a random manner, whereas motile cells establish a single dominant pseudopodium in the direction of movement. This is a critical step necessary for cell migration and occurs prior to cell body translocation, yet little is known about how this process is regulated. Here we show that myosin II light chain (MLC) phosphorylation at its regulatory serine 19 is elevated in growing and retracting pseudopodia. MLC phosphorylation in the extending pseudopodium was associated with strong and persistent amplification of extracellular-regulated signal kinase (ERK) and MLC kinase activity, which specifically localized to the leading pseudopodium. Interestingly, inhibition of ERK or MLC kinase activity prevented MLC phosphorylation and pseudopodia extension but not retraction. In contrast, inhibition of RhoA activity specifically decreased pseudopodia retraction but not extension. Importantly, inhibition of RhoA activity specifically blocked MLC phosphorylation associated with retracting pseudopodia. Inhibition of either ERK or RhoA signals prevents chemotaxis, indicating that both pathways contribute to the establishment of cell polarity and migration. Together, these findings demonstrate that ERK and RhoA are distinct pathways that control pseudopodia extension and retraction, respectively, through differential modulation of MLC phosphorylation and contractile processes.
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Affiliation(s)
- Anar A Brahmbhatt
- Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA
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13
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Sroka J, Madeja Z, Michalik M, Przestalski S, Korohoda W. Folic acid, ascorbic acid and sodium selenite restore the motility of Dictyostelium discoideum inhibited by triethyllead. Toxicology 2002; 180:275-92. [PMID: 12393296 DOI: 10.1016/s0300-483x(02)00419-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The effect of triethyllead (TriEL) on motile activity, structure of cytoskeleton and chemotaxis of Dictyostelium discoideum amoebae in developing concentration gradients of folic acid (FA) and cAMP has been studied. It was observed that 3 microM TriEL had little or no effect on locomotion and chemotactic response of cells, whereas 5 microM TriEL strongly reduced the motile activity of Dictyostelium discoideum amoebae and inhibited their chemotaxis towards cAMP, but not towards FA. FA was found to restore the motile activity of Dictyostelium discoideum, inhibited by TriEL. A similar effect was observed in the presence of other antioxidants, i.e. ascorbic acid and sodium selenite, suggesting that oxidative stress may be involved in the action of TriEL. Moreover, the treatment of Dictyostelium amoebae with 5 microM TriEL caused disruption of microtubules while 3 microM TriEL had little effect on their structure. FA caused restoration of microtubules only in some cells within 1 h of incubation, i.e. when the directional movement of cells towards this chemoattractant was already observed. However, their organization was significantly different from that observed in the untreated cells, suggesting that microtubule undisturbed organisation may be not necessary for Dictyostelium discoideum amoebae locomotion and chemotaxis
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Affiliation(s)
- Jolanta Sroka
- Department of Cell Biology, The J. Zurzycki Institute of Molecular Biology and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Krakow, Poland.
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14
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Abstract
Migrating cells display a characteristic polarization of the actin cytoskeleton. Actin filaments polymerise in the protruding front of the cell whereas actin filament bundles contract in the cell body, which results in retraction of the cell’s rear. The dynamic organization of the actin cytoskeleton provides the force for cell motility and is regulated by small GTPases of the Rho family, in particular Rac1, RhoA and Cdc42. Although the microtubule cytoskeleton is also polarized in a migrating cell, and microtubules are essential for the directed migration of many cell types, their role in cell motility is not well understood at a molecular level. Here, we discuss the potential molecular mechanisms for interplay of microtubules, actin and Rho GTPase signalling in cell polarization and motility. Recent evidence suggests that microtubules locally modulate the activity of Rho GTPases and, conversely, Rho GTPases might be responsible for the initial polarization of the microtubule cytoskeleton. Thus, microtubules might be part of a positive feedback mechanism that maintains the stable polarization of a directionally migrating cell.
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Affiliation(s)
- T Wittmann
- The Scripps Research Institute, Department of Cell Biology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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15
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Sroka J, Madeja Z, Galanty A, Michalik M, Przestalski S, Rakoczy L, Korohoda W. Trimethyltin inhibits the chemotaxis ofDictyostelium discoideum amoebae. Eur J Protistol 2001. [DOI: 10.1078/0932-4739-00834] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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16
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Abstract
Although molecular components of signal transduction pathways are rapidly being identified, how elements of these pathways are positioned spatially and how signals traverse the intracellular environment from the cell surface to the nucleus or to other cytoplasmic targets are not well understood. The discovery of signaling molecules that interact with microtubules (MTs), as well as the multiple effects on signaling pathways of drugs that destabilize or hyperstabilize MTs, indicate that MTs are likely to be critical to the spatial organization of signal transduction. MTs themselves are also affected by signaling pathways and this may contribute to the transmission of signals to downstream targets.
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Affiliation(s)
- G G Gundersen
- Department of Anatomy and Cell Biology Columbia University 630 West 168th Street New York NY 10032 USA.
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18
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Cell shape, motility and distribution of F-actin in amoebae of the mycetozoans Protostelium mycophaga and Acrasis rosea. A comparison with Dictyostelium discoideum. Eur J Protistol 1997. [DOI: 10.1016/s0932-4739(97)80051-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Ueda M, Gräf R, MacWilliams HK, Schliwa M, Euteneuer U. Centrosome positioning and directionality of cell movements. Proc Natl Acad Sci U S A 1997; 94:9674-8. [PMID: 9275182 PMCID: PMC23248 DOI: 10.1073/pnas.94.18.9674] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/1997] [Indexed: 02/05/2023] Open
Abstract
In several cell types, an intriguing correlation exists between the position of the centrosome and the direction of cell movement: the centrosome is located behind the leading edge, suggesting that it serves as a steering device for directional movement. A logical extension of this suggestion is that a change in the direction of cell movement is preceded by a reorientation, or shift, of the centrosome in the intended direction of movement. We have used a fusion protein of green fluorescent protein (GFP) and gamma-tubulin to label the centrosome in migrating amoebae of Dictyostelium discoideum, allowing us to determine the relationship of centrosome positioning and the direction of cell movement with high spatial and temporal resolution in living cells. We find that the extension of a new pseudopod in a migrating cell precedes centrosome repositioning. An average of 12 sec elapses between the initiation of pseudopod extension and reorientation of the centrosome. If no reorientation occurs within approximately 30 sec, the pseudopod is retracted. Thus the centrosome does not direct a cell's migration. However, its repositioning stabilizes a chosen direction of movement, most probably by means of the microtubule system.
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Affiliation(s)
- M Ueda
- Adolf Butenandt Institute, Cell Biology, University of Munich, Munich, Germany.
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20
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Wadsworth P, Bottaro DP. Microtubule dynamic turnover is suppressed during polarization and stimulated in hepatocyte growth factor scattered Madin-Darby canine kidney epithelial cells. CELL MOTILITY AND THE CYTOSKELETON 1996; 35:225-36. [PMID: 8913643 DOI: 10.1002/(sici)1097-0169(1996)35:3<225::aid-cm5>3.0.co;2-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The dynamic behavior of microtubules has been measured in non-polarized, polarized, and hepatocyte growth factor treated Madin-Darby canine kidney epithelial cells. In a nocodazole disassembly assay, microtubules in polarized cells were more resistant to depolymerization than microtubules in non-polarized cells; microtubules in scattered cells were nearly completely disassembled. Analysis of fluorescent microtubules in living cells further revealed that individual microtubules in polarized cells were kinetically stabilized and microtubules in scattered cells were highly dynamic. Individual microtubule behavior in polarized cells was characterized by a suppression of the average rate of shortening, an increase in the average duration of pause, a decrease in the frequency of catastrophe transitions, and an increase in the frequency of rescue transitions, when compared with microtubules in non-polarized cells. In contrast, microtubule behavior in epithelial cells treated with hepatocyte growth factor was characterized by increase in the average rates of microtubule growth and shortening, a decrease in the frequency of rescue transitions, and an increase in the frequency of catastrophe transitions, when compared with polarized cells. Dynamicity, a measure of the gain and loss of subunits from microtubule plus ends, was 2.7 microns/min in polarized cells and 11.1 microns/min in scattered cells. These results demonstrate that individual microtubule dynamic behavior is markedly suppressed in polarized epithelial cells. Our results further demonstrate that in addition to its previously characterized effects on cell locomotion, hepatocyte growth factor stimulates microtubule dynamic turnover in lamellar regions of living cells.
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Affiliation(s)
- P Wadsworth
- Department of Biology, University of Massachusetts, Amherst 01003, USA
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