1
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Wang Y, Hsu AY, Walton EM, Park SJ, Syahirah R, Wang T, Zhou W, Ding C, Lemke AP, Zhang G, Tobin DM, Deng Q. A robust and flexible CRISPR/Cas9-based system for neutrophil-specific gene inactivation in zebrafish. J Cell Sci 2021; 134:237799. [PMID: 33722979 DOI: 10.1242/jcs.258574] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 03/01/2021] [Indexed: 12/17/2022] Open
Abstract
CRISPR/Cas9-based tissue-specific knockout techniques are essential for probing the functions of genes in embryonic development and disease using zebrafish. However, the lack of capacity to perform gene-specific rescue or live imaging in the tissue-specific knockout background has limited the utility of this approach. Here, we report a robust and flexible gateway system for tissue-specific gene inactivation in neutrophils. Using a transgenic fish line with neutrophil-restricted expression of Cas9 and ubiquitous expression of single guide (sg)RNAs targeting rac2, specific disruption of the rac2 gene in neutrophils is achieved. Transient expression of sgRNAs targeting rac2 or cdk2 in the neutrophil-restricted Cas9 line also results in significantly decreased cell motility. Re-expressing sgRNA-resistant rac2 or cdk2 genes restores neutrophil motility in the corresponding knockout background. Moreover, active Rac and force-bearing F-actins localize to both the cell front and the contracting tail during neutrophil interstitial migration in an oscillating fashion that is disrupted when rac2 is knocked out. Together, our work provides a potent tool that can be used to advance the utility of zebrafish in identifying and characterizing gene functions in a tissue-specific manner.
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Affiliation(s)
- Yueyang Wang
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Alan Y Hsu
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Eric M Walton
- Department of Molecular Genetics and Microbiology, and Immunology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Sung Jun Park
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA
| | - Ramizah Syahirah
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Tianqi Wang
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Wenqing Zhou
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Chang Ding
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Abby Pei Lemke
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - GuangJun Zhang
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA.,Purdue Institute for Inflammation, Immunology, & Infectious Disease, Purdue University, West Lafayette, IN 47907, USA.,Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - David M Tobin
- Department of Molecular Genetics and Microbiology, and Immunology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Qing Deng
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.,Purdue Institute for Inflammation, Immunology, & Infectious Disease, Purdue University, West Lafayette, IN 47907, USA.,Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
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2
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Di Blasio L, Gagliardi PA, Puliafito A, Primo L. Serine/Threonine Kinase 3-Phosphoinositide-Dependent Protein Kinase-1 (PDK1) as a Key Regulator of Cell Migration and Cancer Dissemination. Cancers (Basel) 2017; 9:cancers9030025. [PMID: 28287465 PMCID: PMC5366820 DOI: 10.3390/cancers9030025] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/07/2017] [Accepted: 03/08/2017] [Indexed: 02/03/2023] Open
Abstract
Dissecting the cellular signaling that governs the motility of eukaryotic cells is one of the fundamental tasks of modern cell biology, not only because of the large number of physiological processes in which cell migration is crucial, but even more so because of the pathological ones, in particular tumor invasion and metastasis. Cell migration requires the coordination of at least four major processes: polarization of intracellular signaling, regulation of the actin cytoskeleton and membrane extension, focal adhesion and integrin signaling and contractile forces generation and rear retraction. Among the molecular components involved in the regulation of locomotion, the phosphatidylinositol-3-kinase (PI3K) pathway has been shown to exert fundamental role. A pivotal node of such pathway is represented by the serine/threonine kinase 3-phosphoinositide-dependent protein kinase-1 (PDPK1 or PDK1). PDK1, and the majority of its substrates, belong to the AGC family of kinases (related to cAMP-dependent protein kinase 1, cyclic Guanosine monophosphate-dependent protein kinase and protein kinase C), and control a plethora of cellular processes, downstream either to PI3K or to other pathways, such as RAS GTPase-MAPK (mitogen-activated protein kinase). Interestingly, PDK1 has been demonstrated to be crucial for the regulation of each step of cell migration, by activating several proteins such as protein kinase B/Akt (PKB/Akt), myotonic dystrophy-related CDC42-binding kinases alpha (MRCKα), Rho associated coiled-coil containing protein kinase 1 (ROCK1), phospholipase C gamma 1 (PLCγ1) and β3 integrin. Moreover, PDK1 regulates cancer cell invasion as well, thus representing a possible target to prevent cancer metastasis in human patients. The aim of this review is to summarize the various mechanisms by which PDK1 controls the cell migration process, from cell polarization to actin cytoskeleton and focal adhesion regulation, and finally, to discuss the evidence supporting a role for PDK1 in cancer cell invasion and dissemination.
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Affiliation(s)
- Laura Di Blasio
- Candiolo Cancer Institute FPO-IRCCS, 10060 Candiolo, Torino, Italy.
| | | | | | - Luca Primo
- Candiolo Cancer Institute FPO-IRCCS, 10060 Candiolo, Torino, Italy.
- Department of Oncology, University of Torino, 10043 Orbassano, Torino, Italy.
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3
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Lange M, Prassler J, Ecke M, Müller-Taubenberger A, Gerisch G. Local Ras activation, PTEN pattern, and global actin flow in the chemotactic responses of oversized cells. J Cell Sci 2016; 129:3462-72. [PMID: 27505897 DOI: 10.1242/jcs.191148] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 08/01/2016] [Indexed: 12/15/2022] Open
Abstract
Chemotactic responses of eukaryotic cells require a signal processing system that translates an external gradient of attractant into directed motion. To challenge the response system to its limits, we increased the size of Dictyostelium discoideum cells by using electric-pulse-induced fusion. Large cells formed multiple protrusions at different sites along the gradient of chemoattractant, independently turned towards the gradient and competed with each other. Finally, these cells succeeded to re-establish polarity by coordinating front and tail activities. To analyse the responses, we combined two approaches, one aimed at local responses by visualising the dynamics of Ras activation at the front regions of reorientating cells, the other at global changes of polarity by monitoring front-to-tail-directed actin flow. Asymmetric Ras activation in turning protrusions underscores that gradients can be sensed locally and translated into orientation. Different to cells of normal size, the polarity of large cells is not linked to an increasing front-to-tail gradient of the PIP3-phosphatase PTEN. But even in large cells, the front communicates with the tail through an actin flow that might act as carrier of a protrusion inhibitor.
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Affiliation(s)
- Markus Lange
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried D-82152, Germany
| | - Jana Prassler
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried D-82152, Germany
| | - Mary Ecke
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried D-82152, Germany
| | - Annette Müller-Taubenberger
- LMU Munich, Department of Cell Biology (Anatomy III), BioMedical Center, Großhaderner Str. 9, Martinsried D-82152, Germany
| | - Günther Gerisch
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried D-82152, Germany
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4
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Iglesias PA, Shi C. Comparison of adaptation motifs: temporal, stochastic and spatial responses. IET Syst Biol 2015; 8:268-81. [PMID: 25478701 DOI: 10.1049/iet-syb.2014.0026] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The cells' ability to adapt to changes in the external environment is crucial for the survival of many organisms. There are two broad classes of signalling networks that achieve perfect adaptation. Both rely on complementary regulation of the response by an external signal and an inhibitory process. In one class of systems, inhibition comes about from the response itself, closing a negative feedback (NFB) loop. In the other, the inhibition comes directly from the external signal in what is referred to as an incoherent feedforward (IFF) loop. Although both systems show adaptive behaviour to constant changes in the level of the stimulus, their response to other forms of stimuli can differ. Here the authors consider the respective response to various such disturbances, including ramp increases, removal of the stimulus and pulses. The authors also consider the effect of stochastic fluctuations in signalling that come about from the interaction of the signalling elements. Finally, the authors consider the possible effect of spatially varying signals. The authors show that both the NFB and the IFF motifs can be used to sense static spatial gradients, under a local excitation, global inhibition assumption. The results may help experimentalists develop protocols that can discriminate between the two adaptation motifs.
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Affiliation(s)
- Pablo A Iglesias
- Departments of Cell Biology, Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.
| | - Changji Shi
- Department of Electrical and Computer Engineering, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
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5
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Affiliation(s)
- Pei-lin Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan;
| | - Mu-ming Poo
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, California, 94720, USA;
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6
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Abstract
The social amoebae Dictyostelium discoideum has long proved a powerful model organism for studying how cells sense and interpret chemoattractant gradients. Because of the rich behavior observed in its response to chemoattractants, as well as the complex nature of the signaling pathways involved, this research has attracted and benefited from the use of theoretical models. Recent quantitative experiments provide support for a popular model: the local excitation, global inhibition mechanism of gradient sensing. Here, I discuss these findings and suggest some important open problems.
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Affiliation(s)
- Pablo A Iglesias
- Department of Electrical and Computer Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA.
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7
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Abstract
Phosphatidylinositol lipids generated through the action of phosphinositide 3-kinase (PI3K) are key mediators of a wide array of biological responses. In particular, their role in the regulation of cell migration has been extensively studied and extends to amoeboid as well as mesenchymal migration. Through the emergence of fluorescent probes that target PI3K products as well as the use of specific inhibitors and knockout technologies, the spatio-temporal distribution of PI3K products in chemotaxing cells has been shown to represent a key anterior polarity signal that targets downstream effectors to actin polymerization. In addition, through intricate cross-talk networks PI3K products have been shown to regulate signals that control posterior effectors. Yet, in more complex environments or in conditions where chemoattractant gradients are steep, a variety of cell types can still chemotax in the absence of PI3K signals. Indeed, parallel signal transduction pathways have been shown to coordinately regulate cell polarity and directed movement. In this chapter, we will review the current role PI3K products play in the regulation of directed cell migration in various cell types, highlight the importance of mathematical modeling in the study of chemotaxis, and end with a brief overview of other signaling cascades known to also regulate chemotaxis.
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Affiliation(s)
- Michael C Weiger
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bldg.37/Rm2066, 20892-4256, Bethesda, MD, USA
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8
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Cai H, Devreotes PN. Moving in the right direction: how eukaryotic cells migrate along chemical gradients. Semin Cell Dev Biol 2011; 22:834-41. [PMID: 21821139 DOI: 10.1016/j.semcdb.2011.07.020] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 07/19/2011] [Accepted: 07/23/2011] [Indexed: 02/07/2023]
Abstract
Many cells have the ability to grow or migrate towards chemical cues. Oriented growth and movement require detection of the external chemical gradient, transduction of signals, and reorganization of the cytoskeleton. Recent studies in Dictyostelium discoideum and mammalian neutrophils have revealed a complex signaling network that enables cells to migrate in chemical gradients.
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Affiliation(s)
- Huaqing Cai
- The Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
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9
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Abstract
Chemotaxis is one of the most fascinating processes in cell biology. Shallow gradients of chemoattractant direct the movement of cells, and an intricate network of signalling pathways somehow instructs the movement apparatus to induce pseudopods in the direction of these gradients. Exciting new experiments have approached chemotaxis from the perspective of the extending pseudopod. These recent studies have revealed that, in the absence of external cues, cells use endogenous signals for the highly ordered extension of pseudopods, which appear mainly as alternating right and left splits. In addition, chemoattractants activate other signalling molecules that induce a positional bias of this basal system, such that the extending pseudopods are oriented towards the gradient. In this Commentary, I review the findings of these recent experiments, which together provide a new view of cell movement and chemotaxis.
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Affiliation(s)
- Peter J M Van Haastert
- Department of Cell Biochemistry, University of Groningen, Kerklaan 30, 9751NN Haren, The Netherlands.
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10
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Shao D, Rappel WJ, Levine H. Computational model for cell morphodynamics. PHYSICAL REVIEW LETTERS 2010; 105:108104. [PMID: 20867552 PMCID: PMC3048783 DOI: 10.1103/physrevlett.105.108104] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Indexed: 05/05/2023]
Abstract
We develop a computational model, based on the phase-field method, for cell morphodynamics and apply it to fish keratocytes. Our model incorporates the membrane bending force and the surface tension and enforces a constant area. Furthermore, it implements a cross-linked actin filament field and an actin bundle field that are responsible for the protrusion and retraction forces, respectively. We show that our model predicts steady state cell shapes with a wide range of aspect ratios, depending on system parameters. Furthermore, we find that the dependence of the cell speed on this aspect ratio matches experimentally observed data.
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Affiliation(s)
- Danying Shao
- Center for Theoretical Biological Physics and Department of Physics, University of California, San Diego, La Jolla, California 92093-0374, USA
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11
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Soh S, Byrska M, Kandere-Grzybowska K, Grzybowski BA. Reaction-diffusion systems in intracellular molecular transport and control. Angew Chem Int Ed Engl 2010; 49:4170-98. [PMID: 20518023 PMCID: PMC3697936 DOI: 10.1002/anie.200905513] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Chemical reactions make cells work only if the participating chemicals are delivered to desired locations in a timely and precise fashion. Most research to date has focused on active-transport mechanisms, although passive diffusion is often equally rapid and energetically less costly. Capitalizing on these advantages, cells have developed sophisticated reaction-diffusion (RD) systems that control a wide range of cellular functions-from chemotaxis and cell division, through signaling cascades and oscillations, to cell motility. These apparently diverse systems share many common features and are "wired" according to "generic" motifs such as nonlinear kinetics, autocatalysis, and feedback loops. Understanding the operation of these complex (bio)chemical systems requires the analysis of pertinent transport-kinetic equations or, at least on a qualitative level, of the characteristic times of the constituent subprocesses. Therefore, in reviewing the manifestations of cellular RD, we also describe basic theory of reaction-diffusion phenomena.
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Affiliation(s)
- Siowling Soh
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208
| | - Marta Byrska
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208
| | - Kristiana Kandere-Grzybowska
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208
| | - Bartosz A. Grzybowski
- Department of Chemistry, Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, Homepage: http://www.dysa.northwestern.edu
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12
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Abstract
Chemotactic eukaryotic cells are able to detect chemoattractant gradients that are both shallow and have a low background concentration. Under these conditions, the noise in the number of bound receptors can be significant and needs to be taken into account in determining the directional sensing process. Here, we quantify numerically the number of bound receptors on the membrane of a disk-shaped cell by using a numerical Monte Carlo tool. The obtained time traces of the receptor occupancy can be used as inputs for any directional sensing model. We investigate the response of the local excitation global inhibition model and a recently developed balanced inactivation model. We determine a measure for the motility of the cell for each model, based on the relevant output variable, as a function of experimental parameters, resulting in several experimentally testable predictions. Furthermore, we show that these two models behave in a qualitatively different fashion when the background concentration is varied. Thus, to properly characterize the sensitivity of cells to receptor occupancy, it is not sufficient to examine the input signal. Rather, one needs to take into account the response of the second messenger pathway.
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13
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Iglesias PA, Devreotes PN. Navigating through models of chemotaxis. Curr Opin Cell Biol 2008; 20:35-40. [DOI: 10.1016/j.ceb.2007.11.011] [Citation(s) in RCA: 220] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 11/29/2007] [Indexed: 12/22/2022]
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Abstract
Motile eukaryotic cells polarize in response to external signals. Numerous mechanisms have been suggested to account for this symmetry breaking and for the ensuing robust polarization. Implicated in this process are various proteins that are recruited to the plasma membrane and segregate at an emergent front or back of the polarizing cell. Among these are PI3K, PTEN, and members of the Rho family GTPases such as Cdc42, Rac, and Rho. Many such proteins, including the Rho GTPases, cycle between active membrane-bound forms and inactive cytosolic forms. In previous work, we have shown that this property, together with appropriate crosstalk, endows a biochemical circuit (Cdc42, Rac, and Rho) with the property of inherent polarizability. Here we show that this property is present in an even simpler system comprised of a single active/inactive protein pair with positive feedback to its own activation. The simplicity of this minimal system also allows us to explain the mechanism using insights from mathematical analysis. The basic idea resides in a well-known property of reaction-diffusion systems with bistable kinetics, namely, propagation of fronts. However, it crucially depends on exchange between active and inactive forms of the chemicals with unequal rates of diffusion, and overall conservation to pin the waves into a stable polar distribution. We refer to these dynamics as wave-pinning and we show that this phenomenon is distinct from Turing-instability-generated pattern formation that occurs in reaction-diffusion systems that appear to be very similar. We explain the mathematical basis of the phenomenon, relate it to spatial segregation of Rho GTPases, and show how it can account for spatial amplification and maintenance of polarity, as well as sensitivity to new stimuli typical in polarization of eukaryotic cells.
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15
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Ueda M, Shibata T. Stochastic signal processing and transduction in chemotactic response of eukaryotic cells. Biophys J 2007; 93:11-20. [PMID: 17416630 PMCID: PMC1914446 DOI: 10.1529/biophysj.106.100263] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Single-molecule imaging analysis of chemotactic response in eukaryotic cells has revealed a stochastic nature in the input signals and the signal transduction processes. This leads to a fundamental question about the signaling processes: how does the signaling system operate under stochastic fluctuations or noise? Here, we report a stochastic model of chemotactic signaling in which noise and signal propagation along the transmembrane signaling pathway by chemoattractant receptors can be analyzed quantitatively. The results obtained from this analysis reveal that the second-messenger-production reactions by the receptors generate noisy signals that contain intrinsic noise inherently generated at this reaction and extrinsic noise propagated from the ligand-receptor binding. Such intrinsic and extrinsic noise limits the directional sensing ability of chemotactic cells, which may explain the dependence of chemotactic accuracy on chemical gradients that has been observed experimentally. Our analysis also reveals regulatory mechanisms for signal improvement in the stochastically operating signaling system by analyzing how the SNR of chemotactic signals can be improved on or deteriorated by the stochastic properties of receptors and second-messenger molecules. Theoretical consideration of noisy signal transduction by chemotactic signaling systems can further be applied to signaling systems in general.
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Affiliation(s)
- Masahiro Ueda
- Laboratories for Nanobiology, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan.
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16
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Charest PG, Firtel RA. Feedback signaling controls leading-edge formation during chemotaxis. Curr Opin Genet Dev 2006; 16:339-47. [PMID: 16806895 DOI: 10.1016/j.gde.2006.06.016] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Accepted: 06/09/2006] [Indexed: 01/17/2023]
Abstract
Chemotactic cells translate shallow chemoattractant gradients into a highly polarized intracellular response that includes the localized production of PI(3,4,5)P(3) on the side of the cell facing the highest chemoattractant concentration. Research over the past decade began to uncover the molecular mechanisms involved in this localized signal amplification controlling the leading edge of chemotaxing cells. These mechanisms have been shown to involve multiple positive feedback loops, in which the PI(3,4,5)P(3) signal amplifies itself independently of the original stimulus, as well as inhibitory signals that restrict PI(3,4,5)P(3) to the leading edge, thereby creating a steep intracellular PI(3,4,5)P(3) gradient. Molecules involved in positive feedback signaling at the leading edge include the small G-proteins Rac and Ras, phosphatidylinositol-3 kinase and F-actin, as part of interlinked feedback loops that lead to a robust production of PI(3,4,5)P(3).
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Affiliation(s)
- Pascale G Charest
- Division of Biological Sciences, and Center for Molecular Genetics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA
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17
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Meier-Schellersheim M, Xu X, Angermann B, Kunkel EJ, Jin T, Germain RN. Key role of local regulation in chemosensing revealed by a new molecular interaction-based modeling method. PLoS Comput Biol 2006; 2:e82. [PMID: 16854213 PMCID: PMC1513273 DOI: 10.1371/journal.pcbi.0020082] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 05/23/2006] [Indexed: 01/11/2023] Open
Abstract
The signaling network underlying eukaryotic chemosensing is a complex combination of receptor-mediated transmembrane signals, lipid modifications, protein translocations, and differential activation/deactivation of membrane-bound and cytosolic components. As such, it provides particularly interesting challenges for a combined computational and experimental analysis. We developed a novel detailed molecular signaling model that, when used to simulate the response to the attractant cyclic adenosine monophosphate (cAMP), made nontrivial predictions about Dictyostelium chemosensing. These predictions, including the unexpected existence of spatially asymmetrical, multiphasic, cyclic adenosine monophosphate–induced PTEN translocation and phosphatidylinositol-(3,4,5)P3 generation, were experimentally verified by quantitative single-cell microscopy leading us to propose significant modifications to the current standard model for chemoattractant-induced biochemical polarization in this organism. Key to this successful modeling effort was the use of “Simmune,” a new software package that supports the facile development and testing of detailed computational representations of cellular behavior. An intuitive interface allows user definition of complex signaling networks based on the definition of specific molecular binding site interactions and the subcellular localization of molecules. It automatically translates such inputs into spatially resolved simulations and dynamic graphical representations of the resulting signaling network that can be explored in a manner that closely parallels wet lab experimental procedures. These features of Simmune were critical to the model development and analysis presented here and are likely to be useful in the computational investigation of many aspects of cell biology. Cells can orient their migration in response to small local differences in the concentration of extracellular chemicals (chemoattractants). Understanding this process (chemosensing) requires analyzing the time and position-dependent behavior of the signaling molecules within the responding cell, making it an especially interesting challenge for both experimental and computational investigation. Here, the authors report the development and testing of a new detailed molecular model of the chemosensing apparatus of the amoeba Dictyostelium discoidium reacting to the chemoattractant cyclic adenosine monophosphate. Computer simulations performed using this model predicted unexpected and previously unreported patterns of changes in the concentration and location of two important intracellular signaling molecules. These predictions were experimentally verified using microscopy, suggesting the need for modifications to the current “standard” model of eukaryotic chemosensing. The high degree of detail in their model was made possible by a new software suite called “Simmune,” which allows biologists to enter information about molecular interactions using a graphical interface. Without requiring the user to write any equations, the software automatically constructs the overall reaction network, simulates the model, and provides several ways to view the biochemistry of simulated cells. This new tool should help biologists to translate qualitative representations of cell biological processes into quantitative, predictive models.
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Affiliation(s)
- Martin Meier-Schellersheim
- Lymphocyte Biology Section and Program in Systems Immunology and Infectious Disease Modeling, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail: (RNG, general correspondence); (MMS, specific correspondence about Simmune)
| | - Xuehua Xu
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Bethesda, Maryland, United States of America
| | - Bastian Angermann
- Lymphocyte Biology Section and Program in Systems Immunology and Infectious Disease Modeling, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- Institute for Theoretical Physics, Faculty for Mathematics and Natural Sciences, University of Hamburg, Hamburg, Germany
| | - Eric J Kunkel
- BioSeek, Inc., Burlingame, California, United States of America
| | - Tian Jin
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Bethesda, Maryland, United States of America
| | - Ronald N Germain
- Lymphocyte Biology Section and Program in Systems Immunology and Infectious Disease Modeling, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail: (RNG, general correspondence); (MMS, specific correspondence about Simmune)
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18
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Yang L, Iglesias PA. Positive feedback may cause the biphasic response observed in the chemoattractant-induced response of Dictyostelium cells. SYSTEMS & CONTROL LETTERS 2006; 55:329-337. [PMID: 17401451 PMCID: PMC1477642 DOI: 10.1016/j.sysconle.2005.08.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
After stimulation by chemoattractant, Dictyostelium cells exhibit a rapid response. The concentrations of several intracellular proteins rise rapidly reaching their maximum levels approximately 5-10 seconds, after which they return to prestimulus levels. This response, which is found in many other chemotaxing cells, is an example of a step disturbance rejection, a process known to biologists as perfect adaptation. Unlike other cells, however, the initial first peak observed in the chemoattractant-induced response of Dictyostelium cells is then followed by a slower, smaller phase peaking approximately one to two minutes after the stimulus. Until recently, the nature of this biphasic response has been poorly understood. Moreover, the origin for the second phase is unknown. In this paper we conjecture the existence of a feedback path between the response and stimulus. Using a mathematical model of the chemoattractant-induced response in cells, and standard tools from control engineering, we show that positive feedback may elicit this second peak.
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Affiliation(s)
- Liu Yang
- Department of Electrical and Computer Engineering The Johns Hopkins University 3400 N. Charles Street, Baltimore, MD 21218 +1-410-516-6026 +1-410-516-5566 (Fax)
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Sun R, Gao P, Chen L, Ma D, Wang J, Oppenheim JJ, Zhang N. Protein kinase C zeta is required for epidermal growth factor-induced chemotaxis of human breast cancer cells. Cancer Res 2005; 65:1433-41. [PMID: 15735031 DOI: 10.1158/0008-5472.can-04-1163] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chemotaxis plays an important role in cancer cell metastasis. In this study, we showed that epidermal growth factor (EGF) was a more potent chemoattractant than chemokine SDF-1alpha/CXCL12 for human breast cancer cell MDA-MB-231. Different inhibitors were used to evaluate the involvement of 12 protein kinase C (PKC) isotypes in the chemotactic signaling pathway. Chelerythrine chloride, an inhibitor of all PKC isotypes, blocked chemotaxis, whereas inhibitors of classic and novel PKC, such as Gö6976, Gö6850, or calphostin C, only impaired EGF-induced chemotaxis to a minor extent by not greater-than32% inhibition. These data suggested that atypical PKC were involved. The ligand-induced actin polymerization and cell adhesion were also similarly dependent on atypical PKC. Immunofluorescent staining showed an EGF-induced, LY294002-sensitive translocation of PKCzeta from the cytosol to the plasma membrane, indicating that EGF was capable of activating PKCzeta, probably via phosphoinositide 3 kinases. A myristoylated PKCzeta pseudosubstrate blocked the chemotaxis with an IC(50) of 20 mumol/L. To expand our investigation, we further showed that in MCF-7 and T47D, two additional human breast cancer cell lines, EGF-activated PKCzeta and the PKCzeta pseudosubstrate, inhibited chemotaxis. Taken together, our data suggest that PKCzeta is an essential component of the EGF-stimulated chemotactic signaling pathway in human breast cancer cells.
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Affiliation(s)
- Ronghua Sun
- Department of Chemical Biology and State Key Laboratory of Molecular Dynamic and Stable Structures, College of Chemistry and Laboratory of Medical Immunology, School of Basic Medical Science, Peking University, Beijing, China
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Ma L, Janetopoulos C, Yang L, Devreotes PN, Iglesias PA. Two complementary, local excitation, global inhibition mechanisms acting in parallel can explain the chemoattractant-induced regulation of PI(3,4,5)P3 response in dictyostelium cells. Biophys J 2004; 87:3764-74. [PMID: 15465874 PMCID: PMC1304889 DOI: 10.1529/biophysj.104.045484] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Chemotaxing cells, such as Dictyostelium and mammalian neutrophils, sense shallow chemoattractant gradients and respond with highly polarized changes in cell morphology and motility. Uniform chemoattractant stimulation induces the transient translocations of several downstream signaling components, including phosphoinositide 3-kinase (PI3K), tensin homology protein (PTEN), and phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3). In contrast, static spatial chemoattractant gradients elicit the persistent, amplified localization of these molecules. We have proposed a model in which the response to chemoattractant is regulated by a balance of a local excitation and a global inhibition, both of which are controlled by receptor occupancy. This model can account for both the transient and spatial responses to chemoattractants, but alone does not amplify the external gradient. In this article, we develop a model in which parallel local excitation, global inhibition mechanisms control the membrane binding of PI3K and PTEN. Together, the action of these enzymes induces an amplified PI(3,4,5)P3 response that agrees quantitatively with experimentally obtained plekstrin homology-green fluorescent protein distributions in latrunculin-treated cells. We compare the model's performance with that of several mutants in which one or both of the enzymes are disrupted. The model accounts for the observed response to multiple, simultaneous chemoattractant cues and can recreate the cellular response to combinations of temporal and spatial stimuli. Finally, we use the model to predict the response of a cell where only a fraction is stimulated by a saturating dose of chemoattractant.
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Affiliation(s)
- Lan Ma
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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Janetopoulos C, Ma L, Devreotes PN, Iglesias PA. Chemoattractant-induced phosphatidylinositol 3,4,5-trisphosphate accumulation is spatially amplified and adapts, independent of the actin cytoskeleton. Proc Natl Acad Sci U S A 2004; 101:8951-6. [PMID: 15184679 PMCID: PMC428453 DOI: 10.1073/pnas.0402152101] [Citation(s) in RCA: 212] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Experiments in amoebae and neutrophils have shown that local accumulations of phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P(3)] mediate the ability of cells to migrate during gradient sensing. To define the nature of this response, we subjected Dictyostelium discoideum cells to measurable temporal and spatial chemotactic inputs and analyzed the accumulation of PI(3,4,5)P(3) on the membrane, as well as the recruitment of the enzymes phosphoinositide 3-kinase and PTEN. In latrunculin-treated cells, spatial gradients elicited a PI(3,4,5)P(3) response only on the front portion of the cell where the response increased more steeply than the gradient and did not depend on its absolute concentration. Phosphoinositide 3-kinase bound to the membrane only at the front, although it was less sharply localized than PI(3,4,5)P(3). Membrane-bound PTEN was highest at the rear and varied inversely with receptor occupancy. The localization of PI(3,4,5)P(3) was enhanced further in untreated polarized cells containing an intact cytoskeleton. Interestingly, the treated cells could respond to two independent gradients simultaneously, demonstrating that a response at the front does not necessarily inhibit the back. Combinations of temporal and spatial stimuli provided evidence of an inhibitory process and showed that a gradient generates a persistent steady-state response independent of a previous history of exposure to chemoattractant. These results support a local excitation/global inhibition model and argue against other schemes proposed to explain directional sensing.
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Affiliation(s)
- Chris Janetopoulos
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
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