1
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Smith SF, Islam AFMT, Alimukhamedov S, Weiss ET, Charest PG. Molecular determinants of Ras-mTORC2 signaling. J Biol Chem 2024; 300:107423. [PMID: 38815864 PMCID: PMC11255897 DOI: 10.1016/j.jbc.2024.107423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Revised: 05/16/2024] [Accepted: 05/20/2024] [Indexed: 06/01/2024] Open
Abstract
Recent research has identified the mechanistic Target of Rapamycin Complex 2 (mTORC2) as a conserved direct effector of Ras proteins. While previous studies suggested the involvement of the Switch I (SWI) effector domain of Ras in binding mTORC2 components, the regulation of the Ras-mTORC2 pathway is not entirely understood. In Dictyostelium, mTORC2 is selectively activated by the Ras protein RasC, and the RasC-mTORC2 pathway then mediates chemotaxis to cAMP and cellular aggregation by regulating the actin cytoskeleton and promoting cAMP signal relay. Here, we investigated the role of specific residues in RasC's SWI, C-terminal allosteric domain, and hypervariable region (HVR) related to mTORC2 activation. Interestingly, our results suggest that RasC SWI residue A31, which was previously implicated in RasC-mediated aggregation, regulates RasC's specific activation by the Aimless RasGEF. On the other hand, our investigation identified a crucial role for RasC SWI residue T36, with secondary contributions from E38 and allosteric domain residues. Finally, we found that conserved basic residues and the adjacent prenylation site in the HVR, which are crucial for RasC's membrane localization, are essential for RasC-mTORC2 pathway activation by allowing for both RasC's own cAMP-induced activation and its subsequent activation of mTORC2. Therefore, our findings revealed new determinants of RasC-mTORC2 pathway specificity in Dictyostelium, contributing to a deeper understanding of Ras signaling regulation in eukaryotic cells.
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Affiliation(s)
- Stephen F Smith
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA
| | - A F M Tariqul Islam
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA
| | | | - Ethan T Weiss
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA
| | - Pascale G Charest
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA; Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA; University of Arizona Cancer Center, Tucson, Arizona, USA.
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2
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Pandey M, Sarkar S, Ghosh SK. Ancestral TALE homeobox protein transcription factor regulates actin dynamics and cellular activities of protozoan parasite Entamoeba invadens. Mol Microbiol 2024. [PMID: 38654540 DOI: 10.1111/mmi.15266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 04/05/2024] [Accepted: 04/10/2024] [Indexed: 04/26/2024]
Abstract
Entamoeba histolytica causes invasive amoebiasis, an important neglected tropical disease with a significant global health impact. The pathogenicity and survival of E. histolytica and its reptilian equivalent, Entamoeba invadens, relies on its ability to exhibit efficient motility, evade host immune responses, and exploit host resources, all of which are governed by the actin cytoskeleton remodeling. Our study demonstrates the early origin and the regulatory role of TALE homeobox protein EiHbox1 in actin-related cellular processes. Several genes involved in different biological pathways, including actin dynamics are differentially expressed in EiHbox1 silenced cells. EiHbox1 silenced parasites showed disrupted F-actin organization and loss of cellular polarity. EiHbox1's presence in the anterior region of migrating cells further suggests its involvement in maintaining cellular polarity. Loss of polarized morphology of EiHbox1 silenced parasites leads to altered motility from fast, directionally persistent, and highly chemotactic to slow, random, and less chemotactic, which subsequently leads to defective aggregation during encystation. EiHbox1 knockdown also resulted in a significant reduction in phagocytic capacity and poor capping response. These findings highlight the importance of EiHbox1 of E. invadens in governing cellular processes crucial for their survival, pathogenicity, and evasion of the host immune system.
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Affiliation(s)
- Meenakshi Pandey
- Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India
| | - Shilpa Sarkar
- Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India
| | - Sudip K Ghosh
- Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India
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3
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Kim W, Jeon TJ. Phosphatidylinositol 3-kinases play a suppressive role in cell motility of vegetative Dictyostelium cells. Biochem Biophys Res Commun 2022; 629:106-111. [PMID: 36116372 DOI: 10.1016/j.bbrc.2022.09.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/06/2022] [Indexed: 11/17/2022]
Abstract
Phosphatidylinositol 3-Kinase (PI3K) is a key regulator of cell motility during chemotaxis and plays an important role in relaying and amplifying the shallow gradient of chemoattractant signals to ultimately mediate rearrangements of the actin cytoskeleton. To determine whether PI3K plays a similar role in electrotaxis as in chemotaxis, we examined directional cell migration in response to an electric field (EF) and unexpectedly found that the role of PI3K in regulating cell motility differs depending on the state of Dictyostelium cells. Contrary to chemotaxis experiments using aggregation-competent cells, in the cell migration assay, we used a recently developed method for electrotaxis using 3-h starved cells. Wild-type cells starved for 3 h showed increased motility in the presence of LY294002, a PI3K inhibitor, whereas aggregation-competent cells showed slightly decreased motility, indicating the effect of LY294002 on cell motility differ depending on the state of the cells. Consistent with these results, pi3k null cells in the vegetative state exhibited increased motility similar to that in the presence of LY294002, compared to wild-type cells. These findings were confirmed through random migration experiments. These results suggest that PI3Ks play a suppressive role in regulating cell motility of vegetative Dictyostelium cells and that the suppressive effect is reversed on inhibition or lack of PI3Ks, leading to high motility.
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Affiliation(s)
- Wonbum Kim
- Department of Integrative Biological Sciences & BK21 FOUR Educational Research Group for Age-associated Disorder Control Technology, Chosun University, Gwangju, 61452, Republic of Korea
| | - Taeck Joong Jeon
- Department of Integrative Biological Sciences & BK21 FOUR Educational Research Group for Age-associated Disorder Control Technology, Chosun University, Gwangju, 61452, Republic of Korea.
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4
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Rodríguez-Fernández JL, Criado-García O. A meta-analysis indicates that the regulation of cell motility is a non-intrinsic function of chemoattractant receptors that is governed independently of directional sensing. Front Immunol 2022; 13:1001086. [PMID: 36341452 PMCID: PMC9630654 DOI: 10.3389/fimmu.2022.1001086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 10/03/2022] [Indexed: 11/30/2022] Open
Abstract
Chemoattraction, defined as the migration of a cell toward a source of a chemical gradient, is controlled by chemoattractant receptors. Chemoattraction involves two basic activities, namely, directional sensing, a molecular mechanism that detects the direction of a source of chemoattractant, and actin-based motility, which allows the migration of a cell towards it. Current models assume first, that chemoattractant receptors govern both directional sensing and motility (most commonly inducing an increase in the migratory speed of the cells, i.e. chemokinesis), and, second, that the signaling pathways controlling both activities are intertwined. We performed a meta-analysis to reassess these two points. From this study emerge two main findings. First, although many chemoattractant receptors govern directional sensing, there are also receptors that do not regulate cell motility, suggesting that is the ability to control directional sensing, not motility, that best defines a chemoattractant receptor. Second, multiple experimental data suggest that receptor-controlled directional sensing and motility can be controlled independently. We hypothesize that this independence may be based on the existence of separated signalling modules that selectively govern directional sensing and motility in chemotactic cells. Together, the information gathered can be useful to update current models representing the signalling from chemoattractant receptors. The new models may facilitate the development of strategies for a more effective pharmacological modulation of chemoattractant receptor-controlled chemoattraction in health and disease.
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5
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Dynamics of Actin Cytoskeleton and Their Signaling Pathways during Cellular Wound Repair. Cells 2022; 11:cells11193166. [PMID: 36231128 PMCID: PMC9564287 DOI: 10.3390/cells11193166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/27/2022] [Accepted: 10/01/2022] [Indexed: 11/17/2022] Open
Abstract
The repair of wounded cell membranes is essential for cell survival. Upon wounding, actin transiently accumulates at the wound site. The loss of actin accumulation leads to cell death. The mechanism by which actin accumulates at the wound site, the types of actin-related proteins participating in the actin remodeling, and their signaling pathways are unclear. We firstly examined how actin accumulates at a wound site in Dictyostelium cells. Actin assembled de novo at the wound site, independent of cortical flow. Next, we searched for actin- and signal-related proteins targeting the wound site. Fourteen of the examined proteins transiently accumulated at different times. Thirdly, we performed functional analyses using gene knockout mutants or specific inhibitors. Rac, WASP, formin, the Arp2/3 complex, profilin, and coronin contribute to the actin dynamics. Finally, we found that multiple signaling pathways related to TORC2, the Elmo/Doc complex, PIP2-derived products, PLA2, and calmodulin are involved in the actin dynamics for wound repair.
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6
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Yadav P, Gond S, Shekher A, Gupta SC, Singh UP, Singh VP. A multifunctional basic pH indicator probe for distinguishable detection of Co 2+, Cu 2+ and Zn 2+ with its utility in mitotracking and monitoring cytoplasmic viscosity in apoptotic cells. Dalton Trans 2022; 51:6927-6935. [PMID: 35445683 DOI: 10.1039/d2dt00286h] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Metal ions such as Co2+, Cu2+ and Zn2+ have extensive applications in biological and industrial realms, but the toxicity caused by these ions poses a serious threat to mankind. However, there is no report in the literature on the development of a chemosensor for distinguishable detection of these toxic ions. Addressing this challenge, a multifunctional probe as a basic pH indicator with both colorimetric and fluorescence turn-on responses has been reported. The probe selectively discriminates Co2+, Cu2+ and Zn2+ ions with brown, dark yellow and greenish yellow colors, respectively, in DMF : water (9 : 1 v/v, HEPES 10 mM). Additionally, a fluorescence turn-on response specific to Zn2+ has also been observed. The sensing mechanism has been explored using UV-Vis, fluorescence spectroscopy and 1H NMR titration and confirmed with computational results. The inhibition of CN isomerization and excited state intramolecular proton transfer (ESIPT) along with chelation enhanced fluorescence emission (CHEF) result in fluorescence enhancement with Zn2+. Job's plot and HRMS spectra confirm a 1 : 1 (L : M) stoichiometry between the probe and metal ions. The probe is able to exhibit excellent viscochromism in DMF : glycerol medium. Live cell imaging on SiHa cells has been successfully performed for intra-cellular detection of Zn2+ at basic pH. Furthermore, the probe displays its utility in mitotracking and monitoring cytoplasmic viscosity changes in SiHa cells. It is efficiently used to recognize the apoptosis process by displaying an enhancement in fluorescence intensity from cancerous SiHa cells to apoptotic cells.
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Affiliation(s)
- Pranjalee Yadav
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
| | - Sarita Gond
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
| | - Anusmita Shekher
- Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Subash Chandra Gupta
- Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.,Department of Biochemistry, All India Institute of Medical Sciences, Guwahati, Assam, India
| | - Udai P Singh
- Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Vinod P Singh
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
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7
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Li D, Sun F, Yang Y, Tu H, Cai H. Gradients of PI(4,5)P2 and PI(3,5)P2 Jointly Participate in Shaping the Back State of Dictyostelium Cells. Front Cell Dev Biol 2022; 10:835185. [PMID: 35186938 PMCID: PMC8855053 DOI: 10.3389/fcell.2022.835185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
Polarity, which refers to the molecular or structural asymmetry in cells, is essential for diverse cellular functions. Dictyostelium has proven to be a valuable system for dissecting the molecular mechanisms of cell polarity. Previous studies in Dictyostelium have revealed a range of signaling and cytoskeletal proteins that function at the leading edge to promote pseudopod extension and migration. In contrast, how proteins are localized to the trailing edge is not well understood. By screening for asymmetrically localized proteins, we identified a novel trailing-edge protein we named Teep1. We show that a charged surface formed by two pleckstrin homology (PH) domains in Teep1 is necessary and sufficient for targeting it to the rear of cells. Combining biochemical and imaging analyses, we demonstrate that Teep1 interacts preferentially with PI(4,5)P2 and PI(3,5)P2in vitro and simultaneous elimination of these lipid species in cells blocks the membrane association of Teep1. Furthermore, a leading-edge localized myotubularin phosphatase likely mediates the removal of PI(3,5)P2 from the front, as well as the formation of a back-to-front gradient of PI(3,5)P2. Together our data indicate that PI(4,5)P2 and PI(3,5)P2 on the plasma membrane jointly participate in shaping the back state of Dictyostelium cells.
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Affiliation(s)
- Dong Li
- School of Life Sciences, University of Science and Technology of China, Hefei, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Feifei Sun
- School of Life Sciences, University of Science and Technology of China, Hefei, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yihong Yang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hui Tu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Huaqing Cai,
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8
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Yang Y, Li D, Chao X, Singh SP, Thomason P, Yan Y, Dong M, Li L, Insall RH, Cai H. Leep1 interacts with PIP3 and the Scar/WAVE complex to regulate cell migration and macropinocytosis. J Cell Biol 2021; 220:212090. [PMID: 33978708 PMCID: PMC8127007 DOI: 10.1083/jcb.202010096] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 03/23/2021] [Accepted: 04/21/2021] [Indexed: 12/20/2022] Open
Abstract
Polarity is essential for diverse functions in many cell types. Establishing polarity requires targeting a network of specific signaling and cytoskeleton molecules to different subregions of the cell, yet the full complement of polarity regulators and how their activities are integrated over space and time to form morphologically and functionally distinct domains remain to be uncovered. Here, by using the model system Dictyostelium and exploiting the characteristic chemoattractant-stimulated translocation of polarly distributed molecules, we developed a proteomic screening approach, through which we identified a leucine-rich repeat domain–containing protein we named Leep1 as a novel polarity regulator. We combined imaging, biochemical, and phenotypic analyses to demonstrate that Leep1 localizes selectively at the leading edge of cells by binding to PIP3, where it modulates pseudopod and macropinocytic cup dynamics by negatively regulating the Scar/WAVE complex. The spatiotemporal coordination of PIP3 signaling, Leep1, and the Scar/WAVE complex provides a cellular mechanism for organizing protrusive structures at the leading edge.
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Affiliation(s)
- Yihong Yang
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Dong Li
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Xiaoting Chao
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shashi P Singh
- Cancer Research UK Beatson Institute, Glasgow, UK.,University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Peter Thomason
- Cancer Research UK Beatson Institute, Glasgow, UK.,University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Yonghong Yan
- National Institute of Biological Sciences, Beijing, China
| | - Mengqiu Dong
- National Institute of Biological Sciences, Beijing, China
| | - Lei Li
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Robert H Insall
- Cancer Research UK Beatson Institute, Glasgow, UK.,University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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9
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Schaap P. From environmental sensing to developmental control: cognitive evolution in dictyostelid social amoebas. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190756. [PMID: 33487113 PMCID: PMC7934950 DOI: 10.1098/rstb.2019.0756] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Dictyostelid social amoebas respond to starvation by self-organizing into multicellular slugs that migrate towards light to construct spore-bearing structures. These behaviours depend on excitable networks that enable amoebas to produce propagating waves of the chemoattractant cAMP, and to respond by directional movement. cAMP additionally regulates cell differentiation throughout development, with differentiation and cell movement being coordinated by interaction of the stalk inducer c-di-GMP with the adenylate cyclase that generates cAMP oscillations. Evolutionary studies indicate how the manifold roles of cAMP in multicellular development evolved from a role as intermediate for starvation-induced encystation in the unicellular ancestor. A merger of this stress response with the chemotaxis excitable networks yielded the developmental complexity and cognitive capabilities of extant Dictyostelia. This article is part of the theme issue ‘Basal cognition: conceptual tools and the view from the single cell’.
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Affiliation(s)
- Pauline Schaap
- School of Life Sciences, University of Dundee, Dundee DD15EH, UK
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10
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Abstract
The Ras oncogene is notoriously difficult to target with specific therapeutics. Consequently, there is interest to better understand the Ras signaling pathways to identify potential targetable effectors. Recently, the mechanistic target of rapamycin complex 2 (mTORC2) was identified as an evolutionarily conserved Ras effector. mTORC2 regulates essential cellular processes, including metabolism, survival, growth, proliferation and migration. Moreover, increasing evidence implicate mTORC2 in oncogenesis. Little is known about the regulation of mTORC2 activity, but proposed mechanisms include a role for phosphatidylinositol (3,4,5)-trisphosphate - which is produced by class I phosphatidylinositol 3-kinases (PI3Ks), well-characterized Ras effectors. Therefore, the relationship between Ras, PI3K and mTORC2, in both normal physiology and cancer is unclear; moreover, seemingly conflicting observations have been reported. Here, we review the evidence on potential links between Ras, PI3K and mTORC2. Interestingly, data suggest that Ras and PI3K are both direct regulators of mTORC2 but that they act on distinct pools of mTORC2: Ras activates mTORC2 at the plasma membrane, whereas PI3K activates mTORC2 at intracellular compartments. Consequently, we propose a model to explain how Ras and PI3K can differentially regulate mTORC2, and highlight the diversity in the mechanisms of mTORC2 regulation, which appear to be determined by the stimulus, cell type, and the molecularly and spatially distinct mTORC2 pools.
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11
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Wang Y, Brieher WM. CD2AP links actin to PI3 kinase activity to extend epithelial cell height and constrain cell area. J Cell Biol 2020; 219:jcb.201812087. [PMID: 31723006 PMCID: PMC7039212 DOI: 10.1083/jcb.201812087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 08/26/2019] [Accepted: 10/21/2019] [Indexed: 01/03/2023] Open
Abstract
Epithelial cells are categorized as cuboidal versus squamous based on the height of the lateral membrane. Wang and Brieher show that CD2AP links PI3K activity to actin assembly to extend the height of the lateral membrane. Maintaining the correct ratio of apical, basal, and lateral membrane domains is important for epithelial physiology. Here, we show that CD2AP is a critical determinant of epithelial membrane proportions. Depletion of CD2AP or phosphoinositide 3-kinase (PI3K) inhibition results in loss of F-actin and expansion of apical–basal domains, which comes at the expense of lateral membrane height in MDCK cells. We demonstrate that the SH3 domains of CD2AP bind to PI3K and are necessary for PI3K activity along lateral membranes and constraining cell area. Tethering the SH3 domains of CD2AP or p110γ to the membrane is sufficient to rescue CD2AP-knockdown phenotypes. CD2AP and PI3K are both upstream and downstream of actin polymerization. Since CD2AP binds to both actin filaments and PI3K, CD2AP might bridge actin assembly to PI3K activation to form a positive feedback loop to support lateral membrane extension. Our results provide insight into the squamous to cuboidal to columnar epithelial transitions seen in complex epithelial tissues in vivo.
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Affiliation(s)
- Yuou Wang
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, IL
| | - William M Brieher
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, IL
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12
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Yoshioka D, Fukushima S, Koteishi H, Okuno D, Ide T, Matsuoka S, Ueda M. Single-molecule imaging of PI(4,5)P 2 and PTEN in vitro reveals a positive feedback mechanism for PTEN membrane binding. Commun Biol 2020; 3:92. [PMID: 32111929 PMCID: PMC7048775 DOI: 10.1038/s42003-020-0818-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/10/2020] [Indexed: 01/21/2023] Open
Abstract
PTEN, a 3-phosphatase of phosphoinositide, regulates asymmetric PI(3,4,5)P3 signaling for the anterior-posterior polarization and migration of motile cells. PTEN acts through posterior localization on the plasma membrane, but the mechanism for this accumulation is poorly understood. Here we developed an in vitro single-molecule imaging assay with various lipid compositions and use it to demonstrate that the enzymatic product, PI(4,5)P2, stabilizes PTEN's membrane-binding. The dissociation kinetics and lateral mobility of PTEN depended on the PI(4,5)P2 density on artificial lipid bilayers. The basic residues of PTEN were responsible for electrostatic interactions with anionic PI(4,5)P2 and thus the PI(4,5)P2-dependent stabilization. Single-molecule imaging in living Dictyostelium cells revealed that these interactions were indispensable for the stabilization in vivo, which enabled efficient cell migration by accumulating PTEN posteriorly to restrict PI(3,4,5)P3 distribution to the anterior. These results suggest that PI(4,5)P2-mediated positive feedback and PTEN-induced PI(4,5)P2 clustering may be important for anterior-posterior polarization.
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Affiliation(s)
- Daisuke Yoshioka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 565-0043, Japan
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Seiya Fukushima
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 565-0043, Japan
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Hiroyasu Koteishi
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan
| | - Daichi Okuno
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan
| | - Toru Ide
- Graduate School of Natural Science and Technology, Okayama University, Okayama-shi, Okayama, 700-8530, Japan
| | - Satomi Matsuoka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 565-0043, Japan.
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan.
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan.
| | - Masahiro Ueda
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 565-0043, Japan.
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan.
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan.
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13
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Baumgardner K, Lin C, Firtel RA, Lacal J. Phosphodiesterase PdeD, dynacortin, and a Kelch repeat-containing protein are direct GSK3 substrates in Dictyostelium that contribute to chemotaxis towards cAMP. Environ Microbiol 2019; 20:1888-1903. [PMID: 29626371 DOI: 10.1111/1462-2920.14126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/29/2018] [Accepted: 04/01/2018] [Indexed: 01/25/2023]
Abstract
The migration of cells according to a diffusible chemical signal in their environment is called chemotaxis, and the slime mold Dictyostelium discoideum is widely used for the study of eukaryotic chemotaxis. Dictyostelium must sense chemicals, such as cAMP, secreted during starvation to move towards the sources of the signal. Previous work demonstrated that the gskA gene encodes the Dictyostelium homologue of glycogen synthase kinase 3 (GSK3), a highly conserved serine/threonine kinase, which plays a major role in the regulation of Dictyostelium chemotaxis. Cells lacking the GskA substrates Daydreamer and GflB exhibited chemotaxis defects less severe than those exhibited by gskA- (GskA null) cells, suggesting that additional GskA substrates might be involved in chemotaxis. Using phosphoproteomics we identify the GskA substrates PdeD, dynacortin and SogA and characterize the phenotypes of their respective null cells in response to the chemoattractant cAMP. All three chemotaxis phenotypes are defective, and in addition, we determine that carboxylesterase D2 is a common downstream effector of GskA, its direct substrates PdeD, GflB and the kinases GlkA and YakA, and that it also contributes to cell migration. Our findings identify new GskA substrates in cAMP signalling and break down the essential role of GskA in myosin II regulation.
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Affiliation(s)
- Kimberly Baumgardner
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA
| | - Connie Lin
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA
| | - Richard A Firtel
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA
| | - Jesus Lacal
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA.,Department of Microbiology and Genetics, University of Salamanca, Campus Miguel de Unamuno, Salamanca, 37007, Spain
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14
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Varennes J, Moon HR, Saha S, Mugler A, Han B. Physical constraints on accuracy and persistence during breast cancer cell chemotaxis. PLoS Comput Biol 2019; 15:e1006961. [PMID: 30970018 PMCID: PMC6476516 DOI: 10.1371/journal.pcbi.1006961] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 04/22/2019] [Accepted: 03/18/2019] [Indexed: 01/19/2023] Open
Abstract
Directed cell motion in response to an external chemical gradient occurs in many biological phenomena such as wound healing, angiogenesis, and cancer metastasis. Chemotaxis is often characterized by the accuracy, persistence, and speed of cell motion, but whether any of these quantities is physically constrained by the others is poorly understood. Using a combination of theory, simulations, and 3D chemotaxis assays on single metastatic breast cancer cells, we investigate the links among these different aspects of chemotactic performance. In particular, we observe in both experiments and simulations that the chemotactic accuracy, but not the persistence or speed, increases with the gradient strength. We use a random walk model to explain this result and to propose that cells’ chemotactic accuracy and persistence are mutually constrained. Our results suggest that key aspects of chemotactic performance are inherently limited regardless of how favorable the environmental conditions are. One of the most ubiquitous and important cell behaviors is chemotaxis: the ability to move in the direction of a chemical gradient. Due to its importance, key aspects of chemotaxis have been quantified for a variety of cells, including the accuracy, persistence, and speed of cell motion. However, whether these aspects are mutually constrained is poorly understood. Can a cell be accurate but not persistent, or vice versa? Here we use theory, simulations, and experiments on cancer cells to uncover mutual constraints on the properties of chemotaxis. Our results suggest that accuracy and persistence are mutually constrained.
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Affiliation(s)
- Julien Varennes
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana, United States of America
| | - Hye-ran Moon
- School of Mechanical Engineering, Purdue University, West Lafayette Indiana, United States of America
| | - Soutick Saha
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana, United States of America
| | - Andrew Mugler
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail: (AM); (BH)
| | - Bumsoo Han
- School of Mechanical Engineering, Purdue University, West Lafayette Indiana, United States of America
- Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail: (AM); (BH)
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15
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Tsirulnikov E, Huta Y, Breitbart H. PKA and PI3K activities during capacitation protect sperm from undergoing spontaneous acrosome reaction. Theriogenology 2019; 128:54-61. [DOI: 10.1016/j.theriogenology.2019.01.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 12/24/2018] [Accepted: 01/31/2019] [Indexed: 12/20/2022]
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16
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Teasley HE, Jeong MP, Kim TH. A calcium-dependent phospholipase A2 (cPLA2) expression is regulated by MIG-6 during endometrial tumorigenesis. Biochem Biophys Res Commun 2019; 511:129-134. [PMID: 30773264 DOI: 10.1016/j.bbrc.2019.02.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 02/07/2019] [Indexed: 12/19/2022]
Abstract
The ovarian steroid hormones, estrogen (E2) and progesterone (P4), are essential regulators of uterine biology. The imbalance of these ovarian steroid hormones leads to uterine diseases such as endometrial cancer, endometriosis, and infertility. Mitogen-inducible gene 6 (MIG-6) is an adaptor protein. MIG-6 mediates P4 signaling and acts as a tumor suppressor during endometrial tumorigenesis in both humans and mice. In previous studies, we developed the conditional knockout of Mig-6 in all uterine compartments (Pgrcre/+Mig-6f/f; Mig-6KO) and endometrial epithelial cell-specific Mig-6 knockout (Sprr2fcre/+Mig-6f/f; Mig-6Ep-KO) mice. Both mouse models developed endometrial hyperplasia and E2-dependent endometrial cancer. P4 treatment significantly decreases aberrant epithelial proliferation and AKT signaling in Mig-6Ep-KO mice but not in Mig-6KO mice. In the present study, we identified a calcium-dependent phospholipase A2 (cPla2) as one of the genes down-regulated by Mig-6 in the uterus. We performed immunohistochemistry and Western Blot analysis to investigate the regulation of cPLA2 by MIG-6 as well as determine the expression patterns of cPLA2 in the uterus. While the expression of cPLA2 was stronger at the uterine epithelial cells of Mig-6KO and Mig-6Ep-KO mice compared to control mice, P4 suppressed the expression of cPLA2 in Mig-6Ep-KO mice but not in Mig-6KO mice. To determine the ovarian steroid hormone regulation of cPLA2, we examined the expression of cPLA2 in ovariectomized control, Mig-6KO, Mig-6Ep-KO, and PRKO mice treated with P4 or E2. After P4 treatment, cPLA2 expression was remarkably reduced in Mig-6Ep-KO mice but not in Mig-6KO mice. However, the expression of cPLA2 was not changed in PRKO mice. Our results identified cPLA2 as a novel target of MIG-6 in the murine uterus and identified its important role during endometrial tumorigenesis.
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Affiliation(s)
- Hanna E Teasley
- Department of Obstetrics, Gynecology & Reproductive Biology, Michigan State University, College of Human Medicine, Grand Rapids, MI, 49503, USA
| | - Munseok Paul Jeong
- Department of Obstetrics, Gynecology & Reproductive Biology, Michigan State University, College of Human Medicine, Grand Rapids, MI, 49503, USA
| | - Tae Hoon Kim
- Department of Obstetrics, Gynecology & Reproductive Biology, Michigan State University, College of Human Medicine, Grand Rapids, MI, 49503, USA.
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17
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Fukushima S, Matsuoka S, Ueda M. Excitable dynamics of Ras triggers spontaneous symmetry breaking of PIP3 signaling in motile cells. J Cell Sci 2019; 132:jcs224121. [PMID: 30745337 PMCID: PMC6432713 DOI: 10.1242/jcs.224121] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 01/31/2019] [Indexed: 12/22/2022] Open
Abstract
Spontaneous cell movement is underpinned by an asymmetric distribution of signaling molecules including small G proteins and phosphoinositides on the cell membrane. However, the molecular network necessary for spontaneous symmetry breaking has not been fully elucidated. Here, we report that, in Dictyostelium discoideum, the spatiotemporal dynamics of GTP bound Ras (Ras-GTP) breaks the symmetry due its intrinsic excitability even in the absence of extracellular spatial cues and downstream signaling activities. A stochastic excitation of local and transient Ras activation induced phosphatidylinositol (3,4,5)-trisphosphate (PIP3) accumulation via direct interaction with Phosphoinositide 3-kinase (PI3K), causing tightly coupled traveling waves that propagated along the membrane. Comprehensive phase analysis of the waves of Ras-GTP and PIP3 metabolism-related molecules revealed the network structure of the excitable system including positive-feedback regulation of Ras-GTP by the downstream PIP3. A mathematical model reconstituted a series of the observed symmetry-breaking phenomena, illustrating the essential involvement of Ras excitability in the cellular decision-making process.
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Affiliation(s)
- Seiya Fukushima
- Department of Biological Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
- RIKEN Center for Biosystems Dynamics Research (BDR), Suita, Osaka 565-0874, Japan
| | - Satomi Matsuoka
- RIKEN Center for Biosystems Dynamics Research (BDR), Suita, Osaka 565-0874, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
| | - Masahiro Ueda
- Department of Biological Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
- RIKEN Center for Biosystems Dynamics Research (BDR), Suita, Osaka 565-0874, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
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18
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Hashimura H, Morimoto YV, Yasui M, Ueda M. Collective cell migration of Dictyostelium without cAMP oscillations at multicellular stages. Commun Biol 2019; 2:34. [PMID: 30701199 PMCID: PMC6345914 DOI: 10.1038/s42003-018-0273-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 12/20/2018] [Indexed: 01/06/2023] Open
Abstract
In Dictyostelium discoideum, a model organism for the study of collective cell migration, extracellular cyclic adenosine 3',5'-monophosphate (cAMP) acts as a diffusible chemical guidance cue for cell aggregation, which has been thought to be important in multicellular morphogenesis. Here we revealed that the dynamics of cAMP-mediated signaling showed a transition from propagating waves to steady state during cell development. Live-cell imaging of cytosolic cAMP levels revealed that their oscillation and propagation in cell populations were obvious for cell aggregation and mound formation stages, but they gradually disappeared when multicellular slugs started to migrate. A similar transition of signaling dynamics occurred with phosphatidylinositol 3,4,5-trisphosphate signaling, which is upstream of the cAMP signal pathway. This transition was programmed with concomitant developmental progression. We propose a new model in which cAMP oscillation and propagation between cells, which are important at the unicellular stage, are unessential for collective cell migration at the multicellular stage.
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Affiliation(s)
- Hidenori Hashimura
- Department of Biological Sciences, Graduate School of Science, Osaka University, Suita, Osaka, 565-0871 Japan
- RIKEN Center for Biosystems Dynamics Research (BDR), Suita, Osaka, 565-0874 Japan
| | - Yusuke V. Morimoto
- RIKEN Center for Biosystems Dynamics Research (BDR), Suita, Osaka, 565-0874 Japan
- Department of Bioscience and Bioinformatics, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Iizuka, Fukuoka, 820-8502 Japan
| | - Masato Yasui
- RIKEN Center for Biosystems Dynamics Research (BDR), Suita, Osaka, 565-0874 Japan
| | - Masahiro Ueda
- Department of Biological Sciences, Graduate School of Science, Osaka University, Suita, Osaka, 565-0871 Japan
- RIKEN Center for Biosystems Dynamics Research (BDR), Suita, Osaka, 565-0874 Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871 Japan
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19
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Khanna P, Lee JS, Sereemaspun A, Lee H, Baeg GH. GRAMD1B regulates cell migration in breast cancer cells through JAK/STAT and Akt signaling. Sci Rep 2018; 8:9511. [PMID: 29934528 PMCID: PMC6015000 DOI: 10.1038/s41598-018-27864-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 06/12/2018] [Indexed: 12/22/2022] Open
Abstract
Dysregulated JAK/STAT signaling has been implicated in breast cancer metastasis, which is associated with high relapse risks. However, mechanisms underlying JAK/STAT signaling-mediated breast tumorigenesis are poorly understood. Here, we showed that GRAMD1B expression is upregulated on IL-6 but downregulated upon treatment with the JAK2 inhibitor AG490 in the breast cancer MDA-MB-231 cells. Notably, Gramd1b knockdown caused morphological changes of the cells, characterized by the formation of membrane ruffling and protrusions, implicating its role in cell migration. Consistently, GRAMD1B inhibition significantly enhanced cell migration, with an increase in the levels of the Rho family of GTPases. We also found that Gramd1b knockdown-mediated pro-migratory phenotype is associated with JAK2/STAT3 and Akt activation, and that JAK2 or Akt inhibition efficiently suppresses the phenotype. Interestingly, AG490 dose-dependently increased p-Akt levels, and our epistasis analysis suggested that the effect of JAK/STAT inhibition on p-Akt is via the regulation of GRAMD1B expression. Taken together, our results suggest that GRAMD1B is a key signaling molecule that functions to inhibit cell migration in breast cancer by negating both JAK/STAT and Akt signaling, providing the foundation for its development as a novel biomarker in breast cancer.
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Affiliation(s)
- Puja Khanna
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, MD10, 4 Medical Drive, 117594, Singapore
| | - Joan Shuying Lee
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, MD10, 4 Medical Drive, 117594, Singapore
| | - Amornpun Sereemaspun
- Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Haeryun Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, South Korea
| | - Gyeong Hun Baeg
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, MD10, 4 Medical Drive, 117594, Singapore.
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20
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Shimasaki K, Watanabe-Takahashi M, Umeda M, Funamoto S, Saito Y, Noguchi N, Kumagai K, Hanada K, Tsukahara F, Maru Y, Shibata N, Naito M, Nishikawa K. Pleckstrin homology domain of p210 BCR-ABL interacts with cardiolipin to regulate its mitochondrial translocation and subsequent mitophagy. Genes Cells 2017; 23:22-34. [PMID: 29205725 DOI: 10.1111/gtc.12544] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 10/30/2017] [Indexed: 02/05/2023]
Abstract
Chronic myeloid leukemia (CML) is caused by the chimeric protein p210 BCR-ABL encoded by a gene on the Philadelphia chromosome. Although the kinase domain of p210 BCR-ABL is an active driver of CML, the pathological role of its pleckstrin homology (PH) domain remains unclear. Here, we carried out phospholipid vesicle-binding assays to show that cardiolipin (CL), a characteristic mitochondrial phospholipid, is a unique ligand of the PH domain. Arg726, a basic amino acid in the ligand-binding region, was crucial for ligand recognition. A subset of wild-type p210 BCR-ABL that was transiently expressed in HEK293 cells was dramatically translocated from the cytosol to mitochondria in response to carbonyl cyanide m-chlorophenylhydrazone (CCCP) treatment, which induces mitochondrial depolarization and subsequent externalization of CL to the organelle's outer membrane, whereas an R726A mutant of the protein was not translocated. Furthermore, only wild-type p210 BCR-ABL, but not the R726A mutant, suppressed CCCP-induced mitophagy and subsequently enhanced reactive oxygen species production. Thus, p210 BCR-ABL can change its intracellular localization via interactions between the PH domain and CL to cope with mitochondrial damage. This suggests that p210 BCR-ABL could have beneficial effects for cancer proliferation, providing new insight into the PH domain's contribution to CML pathogenesis.
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Affiliation(s)
- Kentaro Shimasaki
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Miho Watanabe-Takahashi
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Masato Umeda
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Satoru Funamoto
- Department of Neuropathology, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Yoshiro Saito
- Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Noriko Noguchi
- Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Keigo Kumagai
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Fujiko Tsukahara
- Department of Pharmacology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Yoshiro Maru
- Department of Pharmacology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Norihito Shibata
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, Tokyo, Japan
| | - Mikihiko Naito
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, Tokyo, Japan
| | - Kiyotaka Nishikawa
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
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21
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GPCR-controlled membrane recruitment of negative regulator C2GAP1 locally inhibits Ras signaling for adaptation and long-range chemotaxis. Proc Natl Acad Sci U S A 2017; 114:E10092-E10101. [PMID: 29109256 DOI: 10.1073/pnas.1703208114] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Eukaryotic cells chemotax in a wide range of chemoattractant concentration gradients, and thus need inhibitory processes that terminate cell responses to reach adaptation while maintaining sensitivity to higher-concentration stimuli. However, the molecular mechanisms underlying inhibitory processes are still poorly understood. Here, we reveal a locally controlled inhibitory process in a GPCR-mediated signaling network for chemotaxis in Dictyostelium discoideum We identified a negative regulator of Ras signaling, C2GAP1, which localizes at the leading edge of chemotaxing cells and is activated by and essential for GPCR-mediated Ras signaling. We show that both C2 and GAP domains are required for the membrane targeting of C2GAP1, and that GPCR-triggered Ras activation is necessary to recruit C2GAP1 from the cytosol and retains it on the membrane to locally inhibit Ras signaling. C2GAP1-deficient c2gapA- cells have altered Ras activation that results in impaired gradient sensing, excessive polymerization of F actin, and subsequent defective chemotaxis. Remarkably, these cellular defects of c2gapA- cells are chemoattractant concentration dependent. Thus, we have uncovered an inhibitory mechanism required for adaptation and long-range chemotaxis.
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22
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Inaba H, Yoda K, Adachi H. The F-actin-binding RapGEF GflB is required for efficient macropinocytosis in Dictyostelium. J Cell Sci 2017; 130:3158-3172. [PMID: 28778987 DOI: 10.1242/jcs.194126] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/26/2017] [Indexed: 01/06/2023] Open
Abstract
Macropinocytosis involves the uptake of large volumes of fluid, which is regulated by various small GTPases. The Dictyostelium discoideum protein GflB is a guanine nucleotide exchange factor (GEF) of Rap1, and is involved in chemotaxis. Here, we studied the role of GflB in macropinocytosis, phagocytosis and cytokinesis. In plate culture of vegetative cells, compared with the parental strain AX2, gflB-knockout (KO) cells were flatter and more polarized, whereas GflB-overproducing cells were rounder. The gflB-KO cells exhibited impaired crown formation and retraction, particularly retraction, resulting in more crowns (macropinocytic cups) per cell and longer crown lifetimes. Accordingly, gflB-KO cells showed defects in macropinocytosis and also in phagocytosis and cytokinesis. F-actin levels were elevated in gflB-KO cells. GflB localized to the actin cortex most prominently at crowns and phagocytic cups. The villin headpiece domain (VHP)-like N-terminal domain of GflB directly interacted with F-actin in vitro Furthermore, a domain enriched in basic amino acids interacted with specific membrane cortex structures such as the cleavage furrow. In conclusion, GflB acts as a key local regulator of actin-driven membrane protrusion possibly by modulating Rap1 signaling pathways.
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Affiliation(s)
- Hironori Inaba
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.,Department of Cell Biology, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan.,The Center for Brain Integration Research, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Koji Yoda
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hiroyuki Adachi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
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23
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Kamp ME, Liu Y, Kortholt A. Function and Regulation of Heterotrimeric G Proteins during Chemotaxis. Int J Mol Sci 2016; 17:ijms17010090. [PMID: 26784171 PMCID: PMC4730333 DOI: 10.3390/ijms17010090] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 12/22/2015] [Accepted: 12/31/2015] [Indexed: 01/10/2023] Open
Abstract
Chemotaxis, or directional movement towards an extracellular gradient of chemicals, is necessary for processes as diverse as finding nutrients, the immune response, metastasis and wound healing. Activation of G-protein coupled receptors (GPCRs) is at the very base of the chemotactic signaling pathway. Chemotaxis starts with binding of the chemoattractant to GPCRs at the cell-surface, which finally leads to major changes in the cytoskeleton and directional cell movement towards the chemoattractant. Many chemotaxis pathways that are directly regulated by Gβγ have been identified and studied extensively; however, whether Gα is just a handle that regulates the release of Gβγ or whether Gα has its own set of distinct chemotactic effectors, is only beginning to be understood. In this review, we will discuss the different levels of regulation in GPCR signaling and the downstream pathways that are essential for proper chemotaxis.
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Affiliation(s)
- Marjon E Kamp
- Department of Cell Biochemistry, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
| | - Youtao Liu
- Department of Cell Biochemistry, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
| | - Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
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24
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Sugiyama T, Pramanik MK, Yumura S. Microtubule-Mediated Inositol Lipid Signaling Plays Critical Roles in Regulation of Blebbing. PLoS One 2015; 10:e0137032. [PMID: 26317626 PMCID: PMC4552846 DOI: 10.1371/journal.pone.0137032] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/11/2015] [Indexed: 12/12/2022] Open
Abstract
Cells migrate by extending pseudopods such as lamellipodia and blebs. Although the signals leading to lamellipodia extension have been extensively investigated, those for bleb extension remain unclear. Here, we investigated signals for blebbing in Dictyostelium cells using a newly developed assay to induce blebbing. When cells were cut into two pieces with a microneedle, the anucleate fragments vigorously extended blebs. This assay enabled us to induce blebbing reproducibly, and analyses of knockout mutants and specific inhibitors identified candidate molecules that regulate blebbing. Blebs were also induced in anucleate fragments of leukocytes, indicating that this assay is generally applicable to animal cells. After cutting, microtubules in the anucleate fragments promptly depolymerized, followed by the extension of blebs. Furthermore, when intact cells were treated with a microtubule inhibitor, they frequently extended blebs. The depolymerization of microtubules induced the delocalization of inositol lipid phosphatidylinositol 3,4,5-trisphosphate from the cell membrane. PI3 kinase-null cells frequently extended blebs, whereas PTEN-null cells extended fewer blebs. From these observations, we propose a model in which microtubules play a critical role in bleb regulation via inositol lipid metabolism.
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Affiliation(s)
- Tatsuroh Sugiyama
- Department of Functional Molecular Biology, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Md. Kamruzzaman Pramanik
- Department of Functional Molecular Biology, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
- Microbiology & Industrial Irradiation Division, IFRB, AERE, Bangladesh Atomic Energy Commission, Dhaka, Bangladesh
| | - Shigehiko Yumura
- Department of Functional Molecular Biology, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
- * E-mail:
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25
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Tsujita K, Itoh T. Phosphoinositides in the regulation of actin cortex and cell migration. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:824-31. [DOI: 10.1016/j.bbalip.2014.10.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 10/08/2014] [Accepted: 10/22/2014] [Indexed: 10/25/2022]
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26
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Rosengarten RD, Santhanam B, Fuller D, Katoh-Kurasawa M, Loomis WF, Zupan B, Shaulsky G. Leaps and lulls in the developmental transcriptome of Dictyostelium discoideum. BMC Genomics 2015; 16:294. [PMID: 25887420 PMCID: PMC4403905 DOI: 10.1186/s12864-015-1491-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 03/26/2015] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Development of the soil amoeba Dictyostelium discoideum is triggered by starvation. When placed on a solid substrate, the starving solitary amoebae cease growth, communicate via extracellular cAMP, aggregate by tens of thousands and develop into multicellular organisms. Early phases of the developmental program are often studied in cells starved in suspension while cAMP is provided exogenously. Previous studies revealed massive shifts in the transcriptome under both developmental conditions and a close relationship between gene expression and morphogenesis, but were limited by the sampling frequency and the resolution of the methods. RESULTS Here, we combine the superior depth and specificity of RNA-seq-based analysis of mRNA abundance with high frequency sampling during filter development and cAMP pulsing in suspension. We found that the developmental transcriptome exhibits mostly gradual changes interspersed by a few instances of large shifts. For each time point we treated the entire transcriptome as single phenotype, and were able to characterize development as groups of similar time points separated by gaps. The grouped time points represented gradual changes in mRNA abundance, or molecular phenotype, and the gaps represented times during which many genes are differentially expressed rapidly, and thus the phenotype changes dramatically. Comparing developmental experiments revealed that gene expression in filter developed cells lagged behind those treated with exogenous cAMP in suspension. The high sampling frequency revealed many genes whose regulation is reproducibly more complex than indicated by previous studies. Gene Ontology enrichment analysis suggested that the transition to multicellularity coincided with rapid accumulation of transcripts associated with DNA processes and mitosis. Later development included the up-regulation of organic signaling molecules and co-factor biosynthesis. Our analysis also demonstrated a high level of synchrony among the developing structures throughout development. CONCLUSIONS Our data describe D. discoideum development as a series of coordinated cellular and multicellular activities. Coordination occurred within fields of aggregating cells and among multicellular bodies, such as mounds or migratory slugs that experience both cell-cell contact and various soluble signaling regimes. These time courses, sampled at the highest temporal resolution to date in this system, provide a comprehensive resource for studies of developmental gene expression.
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Affiliation(s)
- Rafael David Rosengarten
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
| | - Balaji Santhanam
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
| | - Danny Fuller
- Section of Cell and Developmental Biology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Mariko Katoh-Kurasawa
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
| | - William F Loomis
- Section of Cell and Developmental Biology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Blaz Zupan
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
- Faculty of Computer and Information Science, University of Ljubljana, Trzaska cesta 25, Ljubljana, SI-1001, Slovenia.
| | - Gad Shaulsky
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
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Milella M, Falcone I, Conciatori F, Cesta Incani U, Del Curatolo A, Inzerilli N, Nuzzo CMA, Vaccaro V, Vari S, Cognetti F, Ciuffreda L. PTEN: Multiple Functions in Human Malignant Tumors. Front Oncol 2015; 5:24. [PMID: 25763354 PMCID: PMC4329810 DOI: 10.3389/fonc.2015.00024] [Citation(s) in RCA: 323] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 01/22/2015] [Indexed: 12/16/2022] Open
Abstract
PTEN is the most important negative regulator of the PI3K signaling pathway. In addition to its canonical, PI3K inhibition-dependent functions, PTEN can also function as a tumor suppressor in a PI3K-independent manner. Indeed, the PTEN network regulates a broad spectrum of biological functions, modulating the flow of information from membrane-bound growth factor receptors to nuclear transcription factors, occurring in concert with other tumor suppressors and oncogenic signaling pathways. PTEN acts through its lipid and protein phosphatase activity and other non-enzymatic mechanisms. Studies conducted over the past 10 years have expanded our understanding of the biological role of PTEN, showing that in addition to its ability to regulate proliferation and cell survival, it also plays an intriguing role in regulating genomic stability, cell migration, stem cell self-renewal, and tumor microenvironment. Changes in PTEN protein levels, location, and enzymatic activity through various molecular mechanisms can generate a continuum of functional PTEN levels in inherited syndromes, sporadic cancers, and other diseases. PTEN activity can indeed, be modulated by mutations, epigenetic silencing, transcriptional repression, aberrant protein localization, and post-translational modifications. This review will discuss our current understanding of the biological role of PTEN, how PTEN expression and activity are regulated, and the consequences of PTEN dysregulation in human malignant tumors.
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Affiliation(s)
- Michele Milella
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Italia Falcone
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Fabiana Conciatori
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Ursula Cesta Incani
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Anais Del Curatolo
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Nicola Inzerilli
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Carmen M A Nuzzo
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Vanja Vaccaro
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Sabrina Vari
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Francesco Cognetti
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
| | - Ludovica Ciuffreda
- Division of Medical Oncology A, Regina Elena National Cancer Institute , Rome , Italy
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Single-molecule tracking of small GTPase Rac1 uncovers spatial regulation of membrane translocation and mechanism for polarized signaling. Proc Natl Acad Sci U S A 2015; 112:E267-76. [PMID: 25561548 DOI: 10.1073/pnas.1409667112] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Polarized Rac1 signaling is a hallmark of many cellular functions, including cell adhesion, motility, and cell division. The two steps of Rac1 activation are its translocation to the plasma membrane and the exchange of nucleotide from GDP to GTP. It is, however, unclear whether these two processes are regulated independent of each other and what their respective roles are in polarization of Rac1 signaling. We designed a single-particle tracking (SPT) method to quantitatively analyze the kinetics of Rac1 membrane translocation in living cells. We found that the rate of Rac1 translocation was significantly elevated in protrusions during cell spreading on collagen. Furthermore, combining FRET sensor imaging with SPT measurements in the same cell, the recruitment of Rac1 was found to be polarized to an extent similar to that of the nucleotide exchange process. Statistical analysis of single-molecule trajectories and optogenetic manipulation of membrane lipids revealed that Rac1 membrane translocation precedes nucleotide exchange, and is governed primarily by interactions with phospholipids, particularly PI(3,4,5)P3, instead of protein factors. Overall, the study highlights the significance of membrane translocation in spatial Rac1 signaling, which is in addition to the traditional view focusing primarily on GEF distribution and exchange reaction.
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29
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Clark J, Kay RR, Kielkowska A, Niewczas I, Fets L, Oxley D, Stephens LR, Hawkins PT. Dictyostelium uses ether-linked inositol phospholipids for intracellular signalling. EMBO J 2014; 33:2188-200. [PMID: 25180230 DOI: 10.15252/embj.201488677] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Inositol phospholipids are critical regulators of membrane biology throughout eukaryotes. The general principle by which they perform these roles is conserved across species and involves binding of differentially phosphorylated inositol head groups to specific protein domains. This interaction serves to both recruit and regulate the activity of several different classes of protein which act on membrane surfaces. In mammalian cells, these phosphorylated inositol head groups are predominantly borne by a C38:4 diacylglycerol backbone. We show here that the inositol phospholipids of Dictyostelium are different, being highly enriched in an unusual C34:1e lipid backbone, 1-hexadecyl-2-(11Z-octadecenoyl)-sn-glycero-3-phospho-(1'-myo-inositol), in which the sn-1 position contains an ether-linked C16:0 chain; they are thus plasmanylinositols. These plasmanylinositols respond acutely to stimulation of cells with chemoattractants, and their levels are regulated by PIPKs, PI3Ks and PTEN. In mammals and now in Dictyostelium, the hydrocarbon chains of inositol phospholipids are a highly selected subset of those available to other phospholipids, suggesting that different molecular selectors are at play in these organisms but serve a common, evolutionarily conserved purpose.
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Affiliation(s)
- Jonathan Clark
- Babraham Biosciences Technology Babraham Research Campus, Cambridge, UK
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Anna Kielkowska
- Babraham Biosciences Technology Babraham Research Campus, Cambridge, UK
| | - Izabella Niewczas
- Babraham Biosciences Technology Babraham Research Campus, Cambridge, UK
| | - Louise Fets
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - David Oxley
- Signalling Programme Babraham Research Campus, Cambridge, UK
| | - Len R Stephens
- Signalling Programme Babraham Research Campus, Cambridge, UK
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30
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Cao X, Yan J, Shu S, Brzostowski JA, Jin T. Arrestins function in cAR1 GPCR-mediated signaling and cAR1 internalization in the development of Dictyostelium discoideum. Mol Biol Cell 2014; 25:3210-21. [PMID: 25143405 PMCID: PMC4196870 DOI: 10.1091/mbc.e14-03-0834] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Evolutionarily conserved arrestin-like proteins are key components of the cAR1-mediated ERK2 activation that controls cAMP cell–cell signaling during Dictyostelium aggregation. They are also involved in ligand-induced cAR1 internalization, which is required for the switch of cAMP receptors during multicellular development. Oscillation of chemical signals is a common biological phenomenon, but its regulation is poorly understood. At the aggregation stage of Dictyostelium discoideum development, the chemoattractant cAMP is synthesized and released at 6-min intervals, directing cell migration. Although the G protein–coupled cAMP receptor cAR1 and ERK2 are both implicated in regulating the oscillation, the signaling circuit remains unknown. Here we report that D. discoideum arrestins regulate the frequency of cAMP oscillation and may link cAR1 signaling to oscillatory ERK2 activity. Cells lacking arrestins (adcB−C−) display cAMP oscillations during the aggregation stage that are twice as frequent as for wild- type cells. The adcB−C− cells also have a shorter period of transient ERK2 activity and precociously reactivate ERK2 in response to cAMP stimulation. We show that arrestin domain–containing protein C (AdcC) associates with ERK2 and that activation of cAR1 promotes the transient membrane recruitment of AdcC and interaction with cAR1, indicating that arrestins function in cAR1-controlled periodic ERK2 activation and oscillatory cAMP signaling in the aggregation stage of D. discoideum development. In addition, ligand-induced cAR1 internalization is compromised in adcB−C− cells, suggesting that arrestins are involved in elimination of high-affinity cAR1 receptors from cell surface after the aggregation stage of multicellular development.
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Affiliation(s)
- Xiumei Cao
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jianshe Yan
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institutes of Health, Rockville, MD 20852
| | - Shi Shu
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Joseph A Brzostowski
- Laboratory of Immunogenetics Imaging Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852
| | - Tian Jin
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institutes of Health, Rockville, MD 20852
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31
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Abstract
The phosphoinositide 3-kinase (PI 3-K) signal relay pathway represents arguably one of the most intensely studied mechanisms by which extracellular signals elicit cellular responses through the generation of second messengers that are associated with cell growth and transformation. This chapter reviews the many landmark discoveries in the PI 3-K signaling pathway in biology and disease, from the identification of a novel phosphoinositide kinase activity associated with transforming oncogenes in the 1980s, to the identification of oncogenic mutations in the catalytic subunit of PI 3-K in the mid 2000s. Two and a half decades of intense research have provided clear evidence that the PI 3-K pathway controls virtually all aspects of normal cellular physiology, and that deregulation of one or more proteins that regulate or transduce the PI 3-K signal ultimately leads to human pathology. The most recent efforts have focused on the development of specific PI 3-K inhibitors that are currently being evaluated in clinical trials for a range of disease states.This chapter is devoted to a historical review of the landmark findings in the PI 3-K from its relatively humble beginnings in the early to mid 1980s up until the present day. When considering the key findings in the history of PI 3-K, it is essential to recognize the landmark studies by Lowell and Mabel Hokin in the 1950s who were the first to describe that extracellular agonists such as acetylcholine could stimulate the incorporation of radiolabeled phosphate into phospholipids (Hokin and Hokin 1953). Their work initiated an entirely new field of lipid signaling, and subsequent studies in the 1970s by Michell and Lapetina who linked phosphoinositide turnover to membrane-associated receptors that initiate intracellular calcium mobilization (Lapetina and Michell 1973). Later studies revealed that the phospholipase-mediated breakdown of the same minor membrane phospholipids such as PtdIns-4,5-P(2) (phosphatidylinositol-4,5-bisphosphate) is responsible for the release of two additional key second messengers, diacylglycerol (DG) and IP(3) (inositol-1,4,5-trisphosphate) (Kirk et al. 1981; Berridge 1983; Berridge et al. 1983). Berridge, Irvine and Schulz then revealed that one of the byproducts of this lipid signal relay pathway is the release of calcium from intracellular stores such as the endoplasmic reticulum (Streb et al. 1983). Finally, pioneering studies by Nishizuka in the late 1970s identified PKC (protein kinase C) as a phospholipid and diacylglycerol-activated serine/threonine protein kinase (Inoue et al. 1977; Takai et al. 1977). At this point, it probably seemed to most at the time that the story was complete, such that hydrolysis of phosphoinositides such as PtdIns-4,5-P(2) and PtdIns-4-P would account for the major mechanisms of agonist-stimulated lipid signaling leading to physiological responses. On the contrary, the story was far from complete and was about to become a lot more complex.
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Affiliation(s)
- Alex Toker
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, EC/CLS-633A, 02130, Boston, MA, USA,
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Moving towards a paradigm: common mechanisms of chemotactic signaling in Dictyostelium and mammalian leukocytes. Cell Mol Life Sci 2014; 71:3711-47. [PMID: 24846395 DOI: 10.1007/s00018-014-1638-8] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/24/2014] [Accepted: 04/29/2014] [Indexed: 12/31/2022]
Abstract
Chemotaxis, or directed migration of cells along a chemical gradient, is a highly coordinated process that involves gradient sensing, motility, and polarity. Most of our understanding of chemotaxis comes from studies of cells undergoing amoeboid-type migration, in particular the social amoeba Dictyostelium discoideum and leukocytes. In these amoeboid cells the molecular events leading to directed migration can be conceptually divided into four interacting networks: receptor/G protein, signal transduction, cytoskeleton, and polarity. The signal transduction network occupies a central position in this scheme as it receives direct input from the receptor/G protein network, as well as feedback from the cytoskeletal and polarity networks. Multiple overlapping modules within the signal transduction network transmit the signals to the actin cytoskeleton network leading to biased pseudopod protrusion in the direction of the gradient. The overall architecture of the networks, as well as the individual signaling modules, is remarkably conserved between Dictyostelium and mammalian leukocytes, and the similarities and differences between the two systems are the subject of this review.
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33
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Zatulovskiy E, Tyson R, Bretschneider T, Kay RR. Bleb-driven chemotaxis of Dictyostelium cells. ACTA ACUST UNITED AC 2014; 204:1027-44. [PMID: 24616222 PMCID: PMC3998804 DOI: 10.1083/jcb.201306147] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Blebs and F-actin-driven pseudopods are alternative ways of extending the leading edge of migrating cells. We show that Dictyostelium cells switch from using predominantly pseudopods to blebs when migrating under agarose overlays of increasing stiffness. Blebs expand faster than pseudopods leaving behind F-actin scars, but are less persistent. Blebbing cells are strongly chemotactic to cyclic-AMP, producing nearly all of their blebs up-gradient. When cells re-orientate to a needle releasing cyclic-AMP, they stereotypically produce first microspikes, then blebs and pseudopods only later. Genetically, blebbing requires myosin-II and increases when actin polymerization or cortical function is impaired. Cyclic-AMP induces transient blebbing independently of much of the known chemotactic signal transduction machinery, but involving PI3-kinase and downstream PH domain proteins, CRAC and PhdA. Impairment of this PI3-kinase pathway results in slow movement under agarose and cells that produce few blebs, though actin polymerization appears unaffected. We propose that mechanical resistance induces bleb-driven movement in Dictyostelium, which is chemotactic and controlled through PI3-kinase.
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He Y, Li D, Cook SL, Yoon MS, Kapoor A, Rao CV, Kenis PJA, Chen J, Wang F. Mammalian target of rapamycin and Rictor control neutrophil chemotaxis by regulating Rac/Cdc42 activity and the actin cytoskeleton. Mol Biol Cell 2013; 24:3369-80. [PMID: 24006489 PMCID: PMC3814157 DOI: 10.1091/mbc.e13-07-0405] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Rictor, a component of mammalian target of rapamycin complex 2 (mTORC2), controls neutrophil chemotaxis by regulating the dynamics of the actin cytoskeleton via Rac and Cdc42. This function of Rictor is independent of mTORC2 and the kinase activity of mTOR. Chemotaxis allows neutrophils to seek out sites of infection and inflammation. The asymmetric accumulation of filamentous actin (F-actin) at the leading edge provides the driving force for protrusion and is essential for the development and maintenance of neutrophil polarity. The mechanism that governs actin cytoskeleton dynamics and assembly in neutrophils has been extensively explored and is still not fully understood. By using neutrophil-like HL-60 cells, we describe a pivotal role for Rictor, a component of mammalian target of rapamycin complex 2 (mTORC2), in regulating assembly of the actin cytoskeleton during neutrophil chemotaxis. Depletion of mTOR and Rictor, but not Raptor, impairs actin polymerization, leading-edge establishment, and directional migration in neutrophils stimulated with chemoattractants. Of interest, depletion of mSin1, an integral component of mTORC2, causes no detectable defects in neutrophil polarity and chemotaxis. In addition, experiments with chemical inhibition and kinase-dead mutants indicate that mTOR kinase activity and AKT phosphorylation are dispensable for chemotaxis. Instead, our results suggest that the small Rho GTPases Rac and Cdc42 serve as downstream effectors of Rictor to regulate actin assembly and organization in neutrophils. Together our findings reveal an mTORC2- and mTOR kinase–independent function and mechanism of Rictor in the regulation of neutrophil chemotaxis.
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Affiliation(s)
- Yuan He
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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35
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Hoeller O, Bolourani P, Clark J, Stephens LR, Hawkins PT, Weiner OD, Weeks G, Kay RR. Two distinct functions for PI3-kinases in macropinocytosis. J Cell Sci 2013; 126:4296-307. [PMID: 23843627 DOI: 10.1242/jcs.134015] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Class-1 PI3-kinases are major regulators of the actin cytoskeleton, whose precise contributions to chemotaxis, phagocytosis and macropinocytosis remain unresolved. We used systematic genetic ablation to examine this question in growing Dictyostelium cells. Mass spectroscopy shows that a quintuple mutant lacking the entire genomic complement of class-1 PI3-kinases retains only 10% of wild-type PtdIns(3,4,5)P3 levels. Chemotaxis to folate and phagocytosis of bacteria proceed normally in the quintuple mutant but macropinocytosis is abolished. In this context PI3-kinases show specialized functions, only one of which is directly linked to gross PtdIns(3,4,5)P3 levels: macropinosomes originate in patches of PtdIns(3,4,5)P3, with associated F-actin-rich ruffles, both of which depend on PI3-kinase 1/2 (PI3K1/2) but not PI3K4, whereas conversion of ruffles into vesicles requires PI3K4. A biosensor derived from the Ras-binding domain of PI3K1 suggests that Ras is activated throughout vesicle formation. Binding assays show that RasG and RasS interact most strongly with PI3K1/2 and PI3K4, and single mutants of either Ras have severe macropinocytosis defects. Thus, the fundamental function of PI3-kinases in growing Dictyostelium cells is in macropinocytosis where they have two distinct functions, supported by at least two separate Ras proteins.
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Affiliation(s)
- Oliver Hoeller
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
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36
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McQuade KJ, Nakajima A, Ilacqua AN, Shimada N, Sawai S. The green tea catechin epigallocatechin gallate (EGCG) blocks cell motility, chemotaxis and development in Dictyostelium discoideum. PLoS One 2013; 8:e59275. [PMID: 23516620 PMCID: PMC3597604 DOI: 10.1371/journal.pone.0059275] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 02/13/2013] [Indexed: 12/31/2022] Open
Abstract
Catechins, flavanols found at high levels in green tea, have received significant attention due to their potential health benefits related to cancer, autoimmunity and metabolic disease, but little is known about the mechanisms by which these compounds affect cellular behavior. Here, we assess whether the model organism Dictyostelium discoideum is a useful tool with which to characterize the effects of catechins. Epigallocatechin gallate (EGCG), the most abundant and potent catechin in green tea, has significant effects on the Dictyostelium life cycle. In the presence of EGCG aggregation is delayed, cells do not stream and development is typically stalled at the loose aggregate stage. The developmental effects very likely result from defects in motility, as EGCG reduces both random movement and chemotaxis of Dictyostelium amoebae. These results suggest that catechins and their derivatives may be useful tools with which to better understand cell motility and development in Dictyostelium and that this organism is a useful model to further characterize the activities of catechins.
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Affiliation(s)
- Kyle J McQuade
- Department of Biological Sciences, Colorado Mesa University, Grand Junction, Colorado, United States of America.
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A Dictyostelium secreted factor requires a PTEN-like phosphatase to slow proliferation and induce chemorepulsion. PLoS One 2013; 8:e59365. [PMID: 23555023 PMCID: PMC3595242 DOI: 10.1371/journal.pone.0059365] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 02/13/2013] [Indexed: 02/02/2023] Open
Abstract
In Dictyostelium discoideum, AprA and CfaD are secreted proteins that inhibit cell proliferation. We found that the proliferation of cells lacking CnrN, a phosphatase and tensin homolog (PTEN)-like phosphatase, is not inhibited by exogenous AprA and is increased by exogenous CfaD. The expression of CnrN in cnrN cells partially rescues these altered sensitivities, suggesting that CnrN is necessary for the ability of AprA and CfaD to inhibit proliferation. Cells lacking CnrN accumulate normal levels of AprA and CfaD. Like cells lacking AprA and CfaD, cnrN cells proliferate faster and reach a higher maximum cell density than wild type cells, tend to be multinucleate, accumulate normal levels of mass and protein per nucleus, and form less viable spores. When cnrN cells expressing myc-tagged CnrN are stimulated with a mixture of rAprA and rCfaD, levels of membrane-associated myc-CnrN increase. AprA also causes chemorepulsion of Dictyostelium cells, and CnrN is required for this process. Combined, these results suggest that CnrN functions in a signal transduction pathway downstream of AprA and CfaD mediating some, but not all, of the effects of AprA and CfaD.
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38
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Xiao H, Li DX, Liu M. Knowledge translation: airway epithelial cell migration and respiratory diseases. Cell Mol Life Sci 2012; 69:4149-62. [PMID: 22718093 PMCID: PMC11115183 DOI: 10.1007/s00018-012-1044-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 05/23/2012] [Accepted: 05/25/2012] [Indexed: 12/17/2022]
Abstract
Airway epithelial cell migration is essential for lung development and growth, as well as the maintenance of respiratory tissue integrity. This vital cellular process is also important for the repair and regeneration of damaged airway epithelium. More importantly, several lung diseases characterized by aberrant tissue remodeling result from the improper repair of damaged respiratory tissue. Epithelial cell migration relies upon extracellular matrix molecules and is further regulated by numerous local, neuronal, and hormonal factors. Under inflammatory conditions, cell migration can also be stimulated by certain cytokines and chemokines. Many well-known environmental factors involved in the pathogenesis of chronic lung diseases (e.g., cigarette smoking, air pollution, alcohol intake, inflammation, viral and bacterial infections) can inhibit airway epithelial cell migration. Further investigation of cellular and molecular mechanisms of cell migration with advanced techniques may provide knowledge that is relevant to physiological and pathological conditions. These studies may eventually lead to the development of therapeutic interventions to improve lung repair and regeneration and to prevent aberrant remodeling in the lung.
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Affiliation(s)
- Helan Xiao
- Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute, University Health Network, Toronto, ON Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON Canada
| | - Debbie X. Li
- Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute, University Health Network, Toronto, ON Canada
| | - Mingyao Liu
- Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute, University Health Network, Toronto, ON Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON Canada
- Departments of Surgery and Medicine, Faculty of Medicine, University of Toronto, Room TMDT 2-814, 101 College Street, Toronto, ON M5G 1L7 Canada
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39
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Huber RJ, O'Day DH. EGF-like peptide-enhanced cell movement in Dictyostelium is mediated by protein kinases and the activity of several cytoskeletal proteins. Cell Signal 2012; 24:1770-80. [PMID: 22588127 DOI: 10.1016/j.cellsig.2012.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 05/07/2012] [Accepted: 05/07/2012] [Indexed: 12/19/2022]
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40
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Tumor suppressor Hippo/MST1 kinase mediates chemotaxis by regulating spreading and adhesion. Proc Natl Acad Sci U S A 2012; 109:13632-7. [PMID: 22847424 DOI: 10.1073/pnas.1211304109] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Chemotaxis depends on a network of parallel pathways that coordinate cytoskeletal events to bias cell movement along a chemoattractant gradient. Using a forward genetic screen in Dictyostelium discoideum, we identified the Ste20 kinase KrsB, a homolog of tumor suppressors Hippo and MST1/2, as a negative regulator of cell spreading and substrate attachment. The excessive adhesion of krsB(-) cells reduced directional movement and prolonged the streaming phase of multicellular aggregation. These phenotypes depended on an intact kinase domain and phosphorylation of a conserved threonine (T176) within the activation loop. Chemoattractants triggered a rapid, transient autophosphorylation of T176 in a heterotrimeric G protein-dependent and PI3K- and TorC2-independent manner. The active phosphorylated form of KrsB acts to decrease adhesion to the substrate. Taken together these studies suggest that cycling between active and inactive forms of KrsB may provide the dynamic regulation of cell adhesion needed for proper cell migration and chemotaxis. KrsB interacts genetically with another D. discoideum Hippo/MST homolog, KrsA, but the two genes are not functionally redundant. These studies show that Hippo/MST proteins, like the tumor suppressor PTEN and oncogenes Ras and PI3K, play a key role in cell morphological events in addition to their role in regulating cell growth.
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41
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Mun H, Jeon TJ. Regulation of actin cytoskeleton by Rap1 binding to RacGEF1. Mol Cells 2012; 34:71-6. [PMID: 22644079 PMCID: PMC3887774 DOI: 10.1007/s10059-012-0097-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 05/02/2012] [Accepted: 05/03/2012] [Indexed: 01/12/2023] Open
Abstract
Rap1 is rapidly and transiently activated in response to chemoattractant stimulation and helps establish cell polarity by locally modulating cytoskeletons. Here, we investigated the mechanisms by which Rap1 controls actin cytoskeletal reorganization in Dictyostelium and found that Rap1 interacts with RacGEF1 in vitro and stimulates F-actin polymerization at the sites where Rap1 is activated upon chemoattractant stimulation. Live cell imaging using GFP-coronin, a reporter for F-actin, demonstrates that cells expressing constitutively active Rap1 (Rap1CA) exhibit a high level of F-actin uniformly distributed at the cortex including the posterior and lateral sides of the chemotaxing cell. Examination of the localization of a PH-domain containing PIP3 reporter, PhdA-GFP, and the activation of Akt/Pkb and other Ras proteins in Rap1CA cells reveals that activated Rap1 has no effect on the production of PIP3 or the activation of Akt/Pkb and Ras proteins in response to chemoattractant stimulation. Rac family proteins are crucial regulators in actin cytoskeletal reorganization. In vitro binding assay using truncated RacGEF1 proteins shows that Rap1 interacts with the DH domain of RacGEF1. Taken together, these results suggest that Rap1-mediated F-actin polymerization probably occurs through the Rac signaling pathway by directly binding to RacGEF1.
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Affiliation(s)
- Hyemin Mun
- Department of Biology, College of Natural Sciences, Chosun University, Gwangju 501-759,
Korea
| | - Taeck J. Jeon
- Department of Biology, College of Natural Sciences, Chosun University, Gwangju 501-759,
Korea
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A secreted protein is an endogenous chemorepellant in Dictyostelium discoideum. Proc Natl Acad Sci U S A 2012; 109:10990-5. [PMID: 22711818 DOI: 10.1073/pnas.1206350109] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chemorepellants may play multiple roles in physiological and pathological processes. However, few endogenous chemorepellants have been identified, and how they function is unclear. We found that the autocrine signal AprA, which is produced by growing Dictyostelium discoideum cells and inhibits their proliferation, also functions as a chemorepellant. Wild-type cells at the edge of a colony show directed movement outward from the colony, whereas cells lacking AprA do not. Cells show directed movement away from a source of recombinant AprA and dialyzed conditioned media from wild-type cells, but not dialyzed conditioned media from aprA(-) cells. The secreted protein CfaD, the G protein Gα8, and the kinase QkgA are necessary for the chemorepellant activity of AprA as well as its proliferation-inhibiting activity, whereas the putative transcription factor BzpN is dispensable for the chemorepellant activity of AprA but necessary for inhibition of proliferation. Phospholipase C and PI3 kinases 1 and 2, which are necessary for the activity of at least one other chemorepellant in Dictyostelium, are not necessary for recombinant AprA chemorepellant activity. Starved cells are not repelled by recombinant AprA, suggesting that aggregation-phase cells are not sensitive to the chemorepellant effect. Cell tracking indicates that AprA affects the directional bias of cell movement, but not cell velocity or the persistence of cell movement. Together, our data indicate that the endogenous signal AprA acts as an autocrine chemorepellant for Dictyostelium cells.
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Halova I, Draberova L, Draber P. Mast cell chemotaxis - chemoattractants and signaling pathways. Front Immunol 2012; 3:119. [PMID: 22654878 PMCID: PMC3360162 DOI: 10.3389/fimmu.2012.00119] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 04/24/2012] [Indexed: 01/09/2023] Open
Abstract
Migration of mast cells is essential for their recruitment within target tissues where they play an important role in innate and adaptive immune responses. These processes rely on the ability of mast cells to recognize appropriate chemotactic stimuli and react to them by a chemotactic response. Another level of intercellular communication is attained by production of chemoattractants by activated mast cells, which results in accumulation of mast cells and other hematopoietic cells at the sites of inflammation. Mast cells express numerous surface receptors for various ligands with properties of potent chemoattractants. They include the stem cell factor (SCF) recognized by c-Kit, antigen, which binds to immunoglobulin E (IgE) anchored to the high affinity IgE receptor (FcεRI), highly cytokinergic (HC) IgE recognized by FcεRI, lipid mediator sphingosine-1-phosphate (S1P), which binds to G protein-coupled receptors (GPCRs). Other large groups of chemoattractants are eicosanoids [prostaglandin E2 and D2, leukotriene (LT) B4, LTD4, and LTC4, and others] and chemokines (CC, CXC, C, and CX3C), which also bind to various GPCRs. Further noteworthy chemoattractants are isoforms of transforming growth factor (TGF) β1–3, which are sensitively recognized by TGF-β serine/threonine type I and II β receptors, adenosine, C1q, C3a, and C5a components of the complement, 5-hydroxytryptamine, neuroendocrine peptide catestatin, tumor necrosis factor-α, and others. Here we discuss the major types of chemoattractants recognized by mast cells, their target receptors, as well as signaling pathways they utilize. We also briefly deal with methods used for studies of mast cell chemotaxis and with ways of how these studies profited from the results obtained in other cellular systems.
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Affiliation(s)
- Ivana Halova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic Prague, Czech Republic
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Poloz Y, O'Day DH. Colchicine affects cell motility, pattern formation and stalk cell differentiation in Dictyostelium by altering calcium signaling. Differentiation 2012; 83:185-99. [PMID: 22381626 DOI: 10.1016/j.diff.2011.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 12/05/2011] [Accepted: 12/23/2011] [Indexed: 11/26/2022]
Abstract
Previous work, verified here, showed that colchicine affects Dictyostelium pattern formation, disrupts morphogenesis, inhibits spore differentiation and induces terminal stalk cell differentiation. Here we show that colchicine specifically induces ecmB expression and enhances accumulation of ecmB-expressing cells at the posterior end of multicellular structures. Colchicine did not induce a nuclear translocation of DimB, a DIF-1 responsive transcription factor in vitro. It also induced terminal stalk cell differentiation in a mutant strain that does not produce DIF-1 (dmtA-) and after the treatment of cells with DIF-1 synthesis inhibitor cerulenin (100 μM). This suggests that colchicine induces the differentiation of ecmB-expressing cells independent of DIF-1 production and likely through a signaling pathway that is distinct from the one that is utilized by DIF-1. Depending on concentration, colchicine enhanced random cell motility, but not chemotaxis, by 3-5 fold (10-50 mM colchicine, respectively) through a Ca(2+)-mediated signaling pathway involving phospholipase C, calmodulin and heterotrimeric G proteins. Colchicine's effects were not due to microtubule depolymerization as other microtubule-depolymerizing agents did not have these effects. Finally normal morphogenesis and stalk and spore cell differentiation of cells treated with 10 mM colchicine were rescued through chelation of Ca2+ by BAPTA-AM and EDTA and calmodulin antagonism by W-7 but not PLC inhibition by U-73122. Morphogenesis or spore cell differentiation of cells treated with 50 mM colchicine could not be rescued by the above treatments but terminal stalk cell differentiation was inhibited by BAPTA-AM, EDTA and W-7, but not U-73122. Thus colchicine disrupts morphogenesis and induces stalk cell differentiation through a Ca(2+)-mediated signaling pathway involving specific changes in gene expression and cell motility.
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Affiliation(s)
- Yekaterina Poloz
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5.
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Abstract
Slender bundled actin containing plasma membrane protrusions, called filopodia, are important for many essential cellular processes like cell adhesion, migration, angiogenesis and the formation of cell-cell contacts. In migrating cells, filopodia are the pioneers at the leading edge which probe the environment for cues. Integrins are cell surface adhesion receptors critically implicated in cell migration and they are transported actively to filopodia tips by an unconventional myosin, myosin-X. Integrin mediated adhesion stabilizes filopodia and promotes cell migration even though integrins are not essential for filopodia initiation. Myosin-X binds also PIP3 and this regulates its activation and localization to filopodia. Filopodia stimulate cell migration in many cell types and increased filopodia density has been described in cancer. Furthermore, several proteins implicated in filopodia formation, like fascin, are also relevant for cancer progression. To investigate this further, we performed a meta-analysis of the expression profiles of 10 filopodia-linked genes in human breast cancer. These data implicated that several different filopodia inducing genes may contribute in a collective manner to cancer progression and the high metastasis rates associated with basal-type breast carcinomas.
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Affiliation(s)
- Antti Arjonen
- Medical Biotechnology; VTT Technical Research Centre of Finland
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Abstract
Dictyostelium discoideum is an excellent model organism for the study of directed cell migration, since Dictyostelium cells show robust chemotactic responses to the chemoattractant cAMP. Many powerful experimental tools are applicable, including forward and reverse genetics, biochemistry, microscopy, and proteomics. Recent studies have demonstrated that many components involved in chemotaxis are functionally conserved between human neutrophils and Dictyostelium amoebae. In this chapter, we describe how to define the functions of proteins that mediate and regulate cell motility, cell polarity, and directional sensing during chemotaxis in Dictyostelium.
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Affiliation(s)
- Huaqing Cai
- Department of Cell Biology, Johns Hopkins University, School of Medicine, 107 Hunterian 107, 725 N. Wolfe St., Baltimore, MD, 21205. Phone: (410) 502-6836
| | - Chuan-Hsiang Huang
- Department of Cell Biology, Johns Hopkins University, School of Medicine, 107 Hunterian 107, 725 N. Wolfe St., Baltimore, MD, 21205. Phone: (410) 502-6836
| | - Peter N. Devreotes
- Department of Cell Biology, Johns Hopkins University, School of Medicine, 107 Hunterian 107, 725 N. Wolfe St., Baltimore, MD, 21205. Phone: (410) 502-6836
| | - Miho Iijima
- Department of Cell Biology, Johns Hopkins University, School of Medicine, 107 Hunterian 107, 725 N. Wolfe St., Baltimore, MD, 21205. Phone: (410) 502-6836
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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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Xu X, Jin T. Imaging G-protein coupled receptor (GPCR)-mediated signaling events that control chemotaxis of Dictyostelium discoideum. J Vis Exp 2011:3128. [PMID: 21969095 DOI: 10.3791/3128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Many eukaryotic cells can detect gradients of chemical signals in their environments and migrate accordingly (1). This guided cell migration is referred as chemotaxis, which is essential for various cells to carry out their functions such as trafficking of immune cells and patterning of neuronal cells (2, 3). A large family of G-protein coupled receptors (GPCRs) detects variable small peptides, known as chemokines, to direct cell migration in vivo (4). The final goal of chemotaxis research is to understand how a GPCR machinery senses chemokine gradients and controls signaling events leading to chemotaxis. To this end, we use imaging techniques to monitor, in real time, spatiotemporal concentrations of chemoattractants, cell movement in a gradient of chemoattractant, GPCR mediated activation of heterotrimeric G-protein, and intracellular signaling events involved in chemotaxis of eukaryotic cells (5-8). The simple eukaryotic organism, Dictyostelium discoideum, displays chemotaxic behaviors that are similar to those of leukocytes, and D. discoideum is a key model system for studying eukaryotic chemotaxis. As free-living amoebae, D. discoideum cells divide in rich medium. Upon starvation, cells enter a developmental program in which they aggregate through cAMP-mediated chemotaxis to form multicullular structures. Many components involved in chemotaxis to cAMP have been identified in D. discoideum. The binding of cAMP to a GPCR (cAR1) induces dissociation of heterotrimeric G-proteins into Gγ and Gβγ subunits (7, 9, 10). Gβγ subunits activate Ras, which in turn activates PI3K, converting PIP(2;) into PIP(3;) on the cell membrane (11-13). PIP(3;) serve as binding sites for proteins with pleckstrin Homology (PH) domains, thus recruiting these proteins to the membrane (14, 15). Activation of cAR1 receptors also controls the membrane associations of PTEN, which dephosphorylates PIP(3;) to PIP(2;)(16, 17). The molecular mechanisms are evolutionarily conserved in chemokine GPCR-mediated chemotaxis of human cells such as neutrophils (18). We present following methods for studying chemotaxis of D. discoideum cells. 1. Preparation of chemotactic component cells. 2. Imaging chemotaxis of cells in a cAMP gradient. 3. Monitoring a GPCR induced activation of heterotrimeric G-protein in single live cells. 4. Imaging chemoattractant-triggered dynamic PIP(3;) responses in single live cells in real time. Our developed imaging methods can be applied to study chemotaxis of human leukocytes.
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Affiliation(s)
- Xuehua Xu
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health
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Abstract
Cells recognize external chemical gradients and translate these environmental cues into amplified intracellular signaling that results in elongated cell shape, actin polymerization toward the leading edge, and movement along the gradient. Mechanisms underlying chemotaxis are conserved evolutionarily from Dictyostelium amoeba to mammalian neutrophils. Recent studies have uncovered several parallel intracellular signaling pathways that crosstalk in chemotaxing cells. Here, we review these signaling mechanisms in Dictyostelium discoideum.
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Affiliation(s)
- Yu Wang
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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50
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Bozzaro S, Eichinger L. The professional phagocyte Dictyostelium discoideum as a model host for bacterial pathogens. Curr Drug Targets 2011; 12:942-54. [PMID: 21366522 PMCID: PMC3267156 DOI: 10.2174/138945011795677782] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Accepted: 10/26/2010] [Indexed: 01/24/2023]
Abstract
The use of simple hosts such as Dictyostelium discoideum in the study of host pathogen interactions offers a number of advantages and has steadily increased in recent years. Infection-specific genes can often only be studied in a very limited way in man and even in the mouse model their analysis is usually expensive, time consuming and technically challenging or sometimes even impossible. In contrast, their functional analysis in D. discoideum and other simple model organisms is often easier, faster and cheaper. Because host-pathogen interactions necessarily involve two organisms, it is desirable to be able to genetically manipulate both the pathogen and its host. Particularly suited are those hosts, like D. discoideum, whose genome sequence is known and annotated and for which excellent genetic and cell biological tools are available in order to dissect the complex crosstalk between host and pathogen. The review focusses on host-pathogen interactions of D. discoideum with Legionella pneumophila, mycobacteria, and Salmonella typhimurium which replicate intracellularly.
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Affiliation(s)
- Salvatore Bozzaro
- Department of Clinical and Biological Sciences, University of Turin, Ospedale S. Luigi, 10043 Orbassano, Italy.
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