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Umarao P, Rath PP, Gourinath S. Cdc42/Rac Interactive Binding Containing Effector Proteins in Unicellular Protozoans With Reference to Human Host: Locks of the Rho Signaling. Front Genet 2022; 13:781885. [PMID: 35186026 PMCID: PMC8847673 DOI: 10.3389/fgene.2022.781885] [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: 09/23/2021] [Accepted: 01/14/2022] [Indexed: 11/23/2022] Open
Abstract
Small GTPases are the key to actin cytoskeleton signaling, which opens the lock of effector proteins to forward the signal downstream in several cellular pathways. Actin cytoskeleton assembly is associated with cell polarity, adhesion, movement and other functions in eukaryotic cells. Rho proteins, specifically Cdc42 and Rac, are the primary regulators of actin cytoskeleton dynamics in higher and lower eukaryotes. Effector proteins, present in an inactive state gets activated after binding to the GTP bound Cdc42/Rac to relay a signal downstream. Cdc42/Rac interactive binding (CRIB) motif is an essential conserved sequence found in effector proteins to interact with Cdc42 or Rac. A diverse range of Cdc42/Rac and their effector proteins have evolved from lower to higher eukaryotes. The present study has identified and further classified CRIB containing effector proteins in lower eukaryotes, focusing on parasitic protozoans causing neglected tropical diseases and taking human proteins as a reference point to the highest evolved organism in the evolutionary trait. Lower eukaryotes’ CRIB containing proteins fall into conventional effector molecules, PAKs (p21 activated kinase), Wiskoit-Aldrich Syndrome proteins family, and some have unique domain combinations unlike any known proteins. We also highlight the correlation between the effector protein isoforms and their selective specificity for Cdc42 or Rac proteins during evolution. Here, we report CRIB containing effector proteins; ten in Dictyostelium and Entamoeba, fourteen in Acanthamoeba, one in Trypanosoma and Giardia. CRIB containing effector proteins that have been studied so far in humans are potential candidates for drug targets in cancer, neurological disorders, and others. Conventional CRIB containing proteins from protozoan parasites remain largely elusive and our data provides their identification and classification for further in-depth functional validations. The tropical diseases caused by protozoan parasites lack combinatorial drug targets as effective paradigms. Targeting signaling mechanisms operative in these pathogens can provide greater molecules in combatting their infections.
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Affiliation(s)
- Preeti Umarao
- Structural Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Pragyan Parimita Rath
- Structural Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Samudrala Gourinath
- Structural Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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Filić V, Mijanović L, Putar D, Talajić A, Ćetković H, Weber I. Regulation of the Actin Cytoskeleton via Rho GTPase Signalling in Dictyostelium and Mammalian Cells: A Parallel Slalom. Cells 2021; 10:1592. [PMID: 34202767 PMCID: PMC8305917 DOI: 10.3390/cells10071592] [Citation(s) in RCA: 4] [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: 05/28/2021] [Revised: 06/16/2021] [Accepted: 06/16/2021] [Indexed: 01/15/2023] Open
Abstract
Both Dictyostelium amoebae and mammalian cells are endowed with an elaborate actin cytoskeleton that enables them to perform a multitude of tasks essential for survival. Although these organisms diverged more than a billion years ago, their cells share the capability of chemotactic migration, large-scale endocytosis, binary division effected by actomyosin contraction, and various types of adhesions to other cells and to the extracellular environment. The composition and dynamics of the transient actin-based structures that are engaged in these processes are also astonishingly similar in these evolutionary distant organisms. The question arises whether this remarkable resemblance in the cellular motility hardware is accompanied by a similar correspondence in matching software, the signalling networks that govern the assembly of the actin cytoskeleton. Small GTPases from the Rho family play pivotal roles in the control of the actin cytoskeleton dynamics. Indicatively, Dictyostelium matches mammals in the number of these proteins. We give an overview of the Rho signalling pathways that regulate the actin dynamics in Dictyostelium and compare them with similar signalling networks in mammals. We also provide a phylogeny of Rho GTPases in Amoebozoa, which shows a variability of the Rho inventories across different clades found also in Metazoa.
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Affiliation(s)
- Vedrana Filić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
| | | | | | | | | | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
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3
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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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4
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Marinović M, Šoštar M, Filić V, Antolović V, Weber I. Quantitative imaging of Rac1 activity in Dictyostelium cells with a fluorescently labelled GTPase-binding domain from DPAKa kinase. Histochem Cell Biol 2016; 146:267-79. [DOI: 10.1007/s00418-016-1440-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2016] [Indexed: 02/06/2023]
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5
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Rho Signaling in Dictyostelium discoideum. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 322:61-181. [DOI: 10.1016/bs.ircmb.2015.10.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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A Cdc42- and Rac-interactive binding (CRIB) domain mediates functions of coronin. Proc Natl Acad Sci U S A 2013; 111:E25-33. [PMID: 24347642 DOI: 10.1073/pnas.1315368111] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Cdc42- and Rac-interactive binding motif (CRIB) of coronin binds to Rho GTPases with a preference for GDP-loaded Rac. Mutation of the Cdc42- and Rac-interactive binding motif abrogates Rac binding. This results in increased 1evels of activated Rac in coronin-deficient Dictyostelium cells (corA(-)), which impacts myosin II assembly. corA(-) cells show increased accumulation of myosin II in the cortex of growth-phase cells. Myosin II assembly is regulated by myosin heavy chain kinase-mediated phosphorylation of its tail. Kinase activity depends on the activation state of the p21-activated kinase a. The myosin II defect of corA(-) mutant is alleviated by dominant-negative p21-activated kinase a. It is rescued by wild-type coronin, whereas coronin carrying a mutated Cdc42- and Rac-interactive binding motif failed to rescue the myosin defect in corA(-) mutant cells. Ectopically expressed myosin heavy chain kinases affinity purified from corA(-) cells show reduced kinase activity. We propose that coronin through its affinity for GDP-Rac regulates the availability of GTP-Rac for activation of downstream effectors.
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Kortholt A, Keizer-Gunnink I, Kataria R, Van Haastert PJM. Ras activation and symmetry breaking during Dictyostelium chemotaxis. J Cell Sci 2013; 126:4502-13. [PMID: 23886948 DOI: 10.1242/jcs.132340] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Central to chemotaxis is the molecular mechanism by which a shallow spatial gradient of chemoattractant induces symmetry breaking of activated signaling molecules. Previously, we have used Dictyostelium mutants to investigate the minimal requirements for chemotaxis, and identified a basal signaling module providing activation of Ras and F-actin at the leading edge. Here, we show that Ras activation after application of a pipette releasing the chemoattractant cAMP has three phases, each depending on specific guanine-nucleotide-exchange factors (GEFs). Initially a transient activation of Ras occurs at the entire cell boundary, which is proportional to the local cAMP concentrations and therefore slightly stronger at the front than in the rear of the cell. This transient Ras activation is present in gα2 (gpbB)-null cells but not in gβ (gpbA)-null cells, suggesting that Gβγ mediates the initial activation of Ras. The second phase is symmetry breaking: Ras is activated only at the side of the cell closest to the pipette. Symmetry breaking absolutely requires Gα2 and Gβγ, but not the cytoskeleton or four cAMP-induced signaling pathways, those dependent on phosphatidylinositol (3,4,5)-triphosphate [PtdIns(3,4,5)P3], cGMP, TorC2 and PLA2. As cells move in the gradient, the crescent of activated Ras in the front half of the cell becomes confined to a small area at the utmost front of the cell. Confinement of Ras activation leads to cell polarization, and depends on cGMP formation, myosin and F-actin. The experiments show that activation, symmetry breaking and confinement of Ras during Dictyostelium chemotaxis uses different G-protein subunits and a multitude of Ras GEFs and GTPase-activating proteins (GAPs).
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Affiliation(s)
- Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
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Kelsey JS, Blumberg DD. A SAP domain-containing protein shuttles between the nucleus and cell membranes and plays a role in adhesion and migration in D. discoideum. Biol Open 2013; 2:396-406. [PMID: 23616924 PMCID: PMC3625868 DOI: 10.1242/bio.20133889] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 01/10/2013] [Indexed: 12/30/2022] Open
Abstract
The AmpA protein reduces cell adhesion, thereby influencing cell migration in Dictyostelium. To understand how ampA influences cell migration, second site suppressors of an AmpA overexpressing cell line were created by REMI mutagenesis. Mutant candidates were identified by their ability to suppress the large plaques that the AmpA overexpressing cells form on bacterial lawns as a result of their increased rate of migration. One suppressor gene, sma, encodes an uncharacterized protein, which contains a SAP DNA-binding domain and a PTEN-like domain. Using sma gene knockouts and Sma-mRFP expressing cell lines, a role for sma in influencing cell migration was uncovered. Knockouts of the sma gene in a wild-type background enhanced chemotaxis. An additional role for Sma in influencing cell–cell adhesion was also demonstrated. Sma protein transitions between cytosolic and nuclear localizations as a function of cell density. In growing cells migrating to folic acid it is localized to regions of actin polymerization and absent from the nucleus. A role for Sma in influencing ampA mRNA levels is also demonstrated. Sma additionally appears to be involved in ampA pathways regulating cell size, actin polymerization, and cell substrate adhesion. We present insights to the SAP domain-containing group of proteins in Dictyostelium and provide evidence of a role for a SAP domain-containing protein shuttling from the nucleus to sites of actin polymerization during chemotaxis to folic acid and influencing the efficiency of migration.
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Affiliation(s)
- Jessica S Kelsey
- Department of Biological Sciences, University of Maryland Baltimore County , 1000 Hilltop Circle, Baltimore, MD 21250 , USA
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Kelsey JS, Fastman NM, Noratel EF, Blumberg DD. Ndm, a coiled-coil domain protein that suppresses macropinocytosis and has effects on cell migration. Mol Biol Cell 2012; 23:3407-19. [PMID: 22809629 PMCID: PMC3431939 DOI: 10.1091/mbc.e12-05-0392] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The ampA gene has a role in cell migration in Dictyostelium discoideum. Cells overexpressing AmpA show an increase in cell migration, forming large plaques on bacterial lawns. A second-site suppressor of this ampA-overexpressing phenotype identified a previously uncharacterized gene, ndm, which is described here. The Ndm protein is predicted to contain a coiled-coil BAR-like domain-a domain involved in endocytosis and membrane bending. ndm-knockout and Ndm-monomeric red fluorescent protein-expressing cell lines were used to establish a role for ndm in suppressing endocytosis. An increase in the rate of endocytosis and in the number of endosomes was detected in ndm(-) cells. During migration ndm(-) cells formed numerous endocytic cups instead of the broad lamellipodia structure characteristic of moving cells. A second lamellipodia-based function-cell spreading-was also defective in the ndm(-) cells. The increase in endocytosis and the defect in lamellipodia formation were associated with reduced chemotaxis in ndm(-) cells. Immunofluorescence results and glutathione S-transferase pull-down assays revealed an association of Ndm with coronin and F-actin. The results establish ndm as a gene important in regulating the balance between formation of endocytic cups and lamellipodia structures.
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Affiliation(s)
- Jessica S Kelsey
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
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10
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Pakes NK, Veltman DM, Rivero F, Nasir J, Insall R, Williams RSB. The Rac GEF ZizB regulates development, cell motility and cytokinesis in Dictyostelium. J Cell Sci 2012; 125:2457-65. [PMID: 22366457 DOI: 10.1242/jcs.100966] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dock (dedicator of cytokinesis) proteins represent a family of guanine nucleotide exchange factors (GEFs) that include the well-studied Dock180 family and the poorly characterised zizimin family. Our current understanding of Dock180 function is that it regulates Rho small GTPases and thus has a role in a number of cell processes, including cell migration, development and division. Here, we use a tractable model for cell motility research, Dictyostelium discoideum, to help elucidate the role of the related zizimin proteins. We show that gene ablation of zizA causes no change in development, whereas ablation of zizB gives rise to an aberrant developmental morphology and a reduction in cell directionality and velocity, and altered cell shape. Fluorescently labelled ZizA protein associates with the microtubule-organising centre (MTOC), whereas ZizB is enriched in the cortex. Overexpression of ZizB also causes an increase in the number of filopodia and a partial inhibition of cytokinesis. Analysis of ZizB protein binding partners shows that it interacts with Rac1a and a range of actin-associated proteins. In conclusion, our work provides insight into the molecular and cellular functions of zizimin GEF proteins, which are shown to have a role in cell movement, filopodia formation and cytokinesis.
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Affiliation(s)
- Nicholl K Pakes
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK
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Filić V, Marinović M, Faix J, Weber I. A dual role for Rac1 GTPases in the regulation of cell motility. J Cell Sci 2012; 125:387-98. [PMID: 22302991 DOI: 10.1242/jcs.089680] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rac proteins are the only canonical Rho family GTPases in Dictyostelium, where they act as key regulators of the actin cytoskeleton. To monitor the dynamics of activated Rac1 in Dictyostelium cells, a fluorescent probe was developed that specifically binds to the GTP-bound form of Rac1. The probe is based on the GTPase-binding domain (GBD) from PAK1 kinase, and was selected on the basis of yeast two-hybrid, GST pull-down and fluorescence resonance energy transfer assays. The PAK1 GBD localizes to leading edges of migrating cells and to endocytotic cups. Similarly to its role in vertebrates, activated Rac1 therefore appears to control de novo actin polymerization at protruding regions of the Dictyostelium cell. Additionally, we found that the IQGAP-related protein DGAP1, which sequesters active Rac1 into a quaternary complex with actin-binding proteins cortexillin I and cortexillin II, localizes to the trailing regions of migrating cells. Notably, PAK1 GBD and DGAP1, which both bind to Rac1-GTP, display mutually exclusive localizations in cell migration, phagocytosis and cytokinesis, and opposite dynamics of recruitment to the cell cortex upon stimulation with chemoattractants. Moreover, cortical localization of the PAK1 GBD depends on the integrity of the actin cytoskeleton, whereas cortical localization of DGAP1 does not. Taken together, these results imply that Rac1 GTPases play a dual role in regulation of cell motility and polarity in Dictyostelium.
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Affiliation(s)
- Vedrana Filić
- Ruder Bošković Institute, Division of Molecular Biology, Bijenička 54, HR-10000 Zagreb, Croatia
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Balest A, Peracino B, Bozzaro S. Legionella pneumophila infection is enhanced in a RacH-null mutant of Dictyostelium. Commun Integr Biol 2011; 4:194-7. [PMID: 21655438 DOI: 10.4161/cib.4.2.14381] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 12/03/2010] [Indexed: 11/19/2022] Open
Abstract
Recently we reported that Dictyostelium cells ingest Legionella pneumophila by macropinocytosis, whereas other bacteria, such as Escherichia coli, Mycobacterium avium, Neisseria meningitidis or Salmonella typhimurium, are taken up by phagocytosis.1 In contrast to phagocytosis, macropinocytosis is partially inhibited by PI3K or PTEN inactivation, whereas both processes are sensitive to PLC inhibition. Independently from reduced uptake, L. pneumophila proliferates more efficiently in PI3K-null than in wild-type cells. PI3K inactivation also neutralizes resistance to infection conferred by constitutively expressing the endo-lysosomal iron transporter Nramp1. We have shown this to be due to altered recruitment of the V-H(+) ATPase, but not Nramp1, in the Legionella-containing vacuole (LCV) early during infection.1 As further evidence for impaired LCV acidification we examine here the effects of disrupting the small G protein RacH on Legionella infection.
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Affiliation(s)
- Alessandra Balest
- Department of Clinical and Biological Sciences; University of Turin; Orbassano, Italy
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Peng HJ, Henkels KM, Mahankali M, Dinauer MC, Gomez-Cambronero J. Evidence for two CRIB domains in phospholipase D2 (PLD2) that the enzyme uses to specifically bind to the small GTPase Rac2. J Biol Chem 2011; 286:16308-20. [PMID: 21378159 PMCID: PMC3091237 DOI: 10.1074/jbc.m110.206672] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 03/01/2011] [Indexed: 11/06/2022] Open
Abstract
Phospholipase D (PLD) and small GTPases are vital to cell signaling. We report that the Rac2 and the PLD2 isoforms exist in the cell as a lipase-GTPase complex that enables the two proteins to elicit their respective functionalities. A strong association between the two molecules was demonstrated by co-immunoprecipitation and was confirmed in living cells by FRET with CFP-Rac2 and YFP-PLD2 fluorescent chimeras. We have identified the amino acids in PLD2 that define a specific binding site to Rac2. This site is composed of two CRIB (Cdc42-and Rac-interactive binding) motifs that we have named "CRIB-1" and "CRIB-2" in and around the PH domain in PLD2. Deletion mutants PLD2-ΔCRIB-1/2 negate co-immunoprecipitation with Rac2 and diminish the FRET signal in living cells. The PLD2-Rac2 association was further confirmed in vitro using affinity-purified recombinant proteins. Binding was saturable with an apparent K(d) of 3 nm and was diminished with PLD2-ΔCRIB mutants. Furthermore, PLD2 bound more efficiently to Rac2-GTP than to Rac2-GDP or to a GDP-constitutive Rac2-N17 mutant. Increasing concentrations of recombinant Rac2 in vitro and in vivo during cell adhesion inhibit PLD2. Conversely, Rac2 activity is increased in the presence of PLD2-WT but not in PLD2-ΔCRIB. We propose that in activated cells PLD2 affects Rac2 in an initial positive feedback, but as Rac2-GTP accumulates in the cell, this constitutes a "termination signal" leading to PLD2 inactivation.
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Affiliation(s)
- Hong-Juan Peng
- From the Department of Biochemistry and Molecular Biology, Wright State University School Medicine, Dayton, Ohio 45435 and
| | - Karen M. Henkels
- From the Department of Biochemistry and Molecular Biology, Wright State University School Medicine, Dayton, Ohio 45435 and
| | - Madhu Mahankali
- From the Department of Biochemistry and Molecular Biology, Wright State University School Medicine, Dayton, Ohio 45435 and
| | - Mary C. Dinauer
- the Herman B. Wells Center for Pediatric Research, Department of Pediatrics (Hematology/Oncology), Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Julian Gomez-Cambronero
- From the Department of Biochemistry and Molecular Biology, Wright State University School Medicine, Dayton, Ohio 45435 and
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Para A, Krischke M, Merlot S, Shen Z, Oberholzer M, Lee S, Briggs S, Firtel RA. Dictyostelium Dock180-related RacGEFs regulate the actin cytoskeleton during cell motility. Mol Biol Cell 2008; 20:699-707. [PMID: 19037099 DOI: 10.1091/mbc.e08-09-0899] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cell motility of amoeboid cells is mediated by localized F-actin polymerization that drives the extension of membrane protrusions to promote forward movements. We show that deletion of either of two members of the Dictyostelium Dock180 family of RacGEFs, DockA and DockD, causes decreased speed of chemotaxing cells. The phenotype is enhanced in the double mutant and expression of DockA or DockD complements the reduced speed of randomly moving DockD null cells' phenotype, suggesting that DockA and DockD are likely to act redundantly and to have similar functions in regulating cell movement. In this regard, we find that overexpressing DockD causes increased cell speed by enhancing F-actin polymerization at the sites of pseudopod extension. DockD localizes to the cell cortex upon chemoattractant stimulation and at the leading edge of migrating cells and this localization is dependent on PI3K activity, suggesting that DockD might be part of the pathway that links PtdIns(3,4,5)P(3) production to F-actin polymerization. Using a proteomic approach, we found that DdELMO1 is associated with DockD and that Rac1A and RacC are possible in vivo DockD substrates. In conclusion, our work provides a further understanding of how cell motility is controlled and provides evidence that the molecular mechanism underlying Dock180-related protein function is evolutionarily conserved.
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Affiliation(s)
- Alessia Para
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0380, USA
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15
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Menotta M, Amicucci A, Basili G, Polidori E, Stocchi V, Rivero F. Molecular and functional characterization of a Rho GDP dissociation inhibitor in the filamentous fungus Tuber borchii. BMC Microbiol 2008; 8:57. [PMID: 18400087 PMCID: PMC2362126 DOI: 10.1186/1471-2180-8-57] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 04/09/2008] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Small GTPases of the Rho family function as tightly regulated molecular switches that govern important cellular functions in eukaryotes. Several families of regulatory proteins control their activation cycle and subcellular localization. Members of the guanine nucleotide dissociation inhibitor (GDI) family sequester Rho GTPases from the plasma membrane and keep them in an inactive form. RESULTS We report on the characterization the RhoGDI homolog of Tuber borchii Vittad., an ascomycetous ectomycorrhizal fungus. The Tbgdi gene is present in two copies in the T. borchii genome. The predicted amino acid sequence shows high similarity to other known RhoGDIs. Real time PCR analyses revealed an increased expression of Tbgdi during the phase preparative to the symbiosis instauration, in particular after stimulation with root exudates extracts, that correlates with expression of Tbcdc42. In a translocation assay TbRhoGDI was able to solubilize TbCdc42 from membranes. Surprisingly, TbRhoGDI appeared not to interact with S. cerevisiae Cdc42, precluding the use of yeast as a surrogate model for functional studies. To study the role of TbRhoGDI we performed complementation experiments using a RhoGDI null strain of Dictyostelium discoideum, a model organism where the roles of Rho signaling pathways are well established. For comparison, complementation with mammalian RhoGDI1 and LyGDI was also studied in the null strain. Although interacting with Rac1 isoforms, TbRhoGDI was not able to revert the defects of the D. discoideum RhoGDI null strain, but displayed an additional negative effect on the cAMP-stimulated actin polymerization response. CONCLUSION T. borchii expresses a functional RhoGDI homolog that appears as an important modulator of cytoskeleton reorganization during polarized apical growth that antecedes symbiosis instauration. The specificity of TbRhoGDI actions was underscored by its inability to elicit a growth defect in S. cerevisiae or to compensate the loss of a D. discoideum RhoGDI. Knowledge of the cell signaling at the basis of cytoskeleton reorganization of ectomycorrhizal fungi is essential for improvements in the production of mycorrhized plant seedlings used in timberland extension programs and fruit body production.
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Affiliation(s)
- Michele Menotta
- Istituto di Chimica Biologica "G. Fornaini," Università degli Studi di Urbino "Carlo Bo," Via Saffi 2, 61029 Urbino (PU), Italy
| | - Antonella Amicucci
- Istituto di Chimica Biologica "G. Fornaini," Università degli Studi di Urbino "Carlo Bo," Via Saffi 2, 61029 Urbino (PU), Italy
| | - Giorgio Basili
- Istituto di Chimica Biologica "G. Fornaini," Università degli Studi di Urbino "Carlo Bo," Via Saffi 2, 61029 Urbino (PU), Italy
| | - Emanuela Polidori
- Istituto di Ricerca sull'Attività Motoria, Università degli Studi di Urbino "Carlo Bo," Via I Maggetti 26, 61029 Urbino (PU), Italy
| | - Vilberto Stocchi
- Istituto di Chimica Biologica "G. Fornaini," Università degli Studi di Urbino "Carlo Bo," Via Saffi 2, 61029 Urbino (PU), Italy
| | - Francisco Rivero
- Center for Biochemistry, Medical Faculty, University of Cologne. Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
- The Hull York Medical School and Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK
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16
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Kortholt A, van Haastert PJM. Highlighting the role of Ras and Rap during Dictyostelium chemotaxis. Cell Signal 2008; 20:1415-22. [PMID: 18385017 DOI: 10.1016/j.cellsig.2008.02.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Accepted: 02/06/2008] [Indexed: 10/22/2022]
Abstract
Chemotaxis, the directional movement towards a chemical compound, is an essential property of many cells and has been linked to the development and progression of many diseases. Eukaryotic chemotaxis is a complex process involving gradient sensing, cell polarity, remodelling of the cytoskeleton and signal relay. Recent studies in the model organism Dictyostelium discoideum have shown that chemotaxis does not depend on a single molecular mechanism, but rather depends on several interconnecting pathways. Surprisingly, small G-proteins appear to play essential roles in all these pathways. This review will summarize the role of small G-proteins in Dictyostelium, particularly highlighting the function of the Ras subfamily in chemotaxis.
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Affiliation(s)
- Arjan Kortholt
- Department of Molecular Cell Biology, University of Groningen, Kerklaan 30, 9751NN Haren, The Netherlands
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17
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Foerg C, Merkle HP. On The Biomedical Promise of Cell Penetrating Peptides: Limits Versus Prospects. J Pharm Sci 2008; 97:144-62. [PMID: 17763452 DOI: 10.1002/jps.21117] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The cell membrane poses a substantial hurdle to the use of pharmacologically active biomacromolecules that are not per se actively translocated into cells. An appealing approach to deliver such molecules involves tethering or complexing them with so-called cell penetrating peptides (CPPs) that are able to cross the plasma membrane of mammalian cells. The CPP approach is currently a major avenue in engineering delivery systems that are hoped to mediate the non-invasive import of problematic cargos into cells. The large number of different cargo molecules that have been efficiently delivered by CPPs ranges from small molecules to proteins and even liposomes and particles. With respect to the involved mechanism(s) there is increasing evidence for endocytosis as a major route of entry. Moreover, in terms of intracellular trafficking, current data argues for the transport to acidic early endosomal compartments with cytosolic release mediated via retrograde delivery through the Golgi apparatus and the endoplasmic reticulum. The focus of this review is to revisit the performance of cell penetrating peptides for drug delivery. To this aim we cover both accomplishments and failures and report on new prospects of the CPP approach. Besides a selection of successful case histories of CPPs we also review the limitations of CPP mediated translocation. In particular, we comment on the impact of (i) metabolic degradation, (ii) the cell line and cellular differentiation state dependent uptake of CPPs, as well as (iii) the regulation of their endocytic traffic by Rho-family GTPases. Further on, we aim at the identification of promising niches for CPP application in drug delivery. In this context, as inspired by current literature, we focus on three principal areas: (i) the delivery of antineoplastic agents, (ii) the delivery of CPPs as antimicrobials, and (iii) the potential of CPPs to target inflammatory tissues.
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Affiliation(s)
- Christina Foerg
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
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18
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Foerg C, Ziegler U, Fernandez-Carneado J, Giralt E, Merkle HP. Differentiation restricted endocytosis of cell penetrating peptides in MDCK cells corresponds with activities of Rho-GTPases. Pharm Res 2007; 24:628-42. [PMID: 17334941 DOI: 10.1007/s11095-006-9212-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2006] [Accepted: 12/08/2006] [Indexed: 01/19/2023]
Abstract
PURPOSE Cellular entry of biomacromolecules is restricted by the barrier function of cell membranes. Tethering such molecules to cell penetrating peptides (CPPs) that can translocate cell membranes has opened new horizons in biomedical research. Here, we investigate the cellular internalization of hCT(9-32)-br, a human calcitonin derived branched CPP, and SAP, a gamma-zein related sequence. METHODS Internalization of fluorescence labelled CPPs was performed with both proliferating and confluent MDCK cells by means of confocal laser scanning microscopy (CLSM) and fluorescence activated cell sorting (FACS) using appropriate controls. Internalization was further elaborated in an inflammatory, IFN-gamma/TNF-alphaa induced confluent MDCK model mimicking inflammatory epithelial pathologies. Activities of active form Rho-GTPases (Rho-A and Rac-1) in proliferating and confluent MDCK cells were monitored by pull-down assay and Western blot analysis. RESULTS We observed marked endocytic uptake of the peptides into proliferating MDCK by a process suggesting both lipid rafts and clathrin-coated pits. In confluent MDCK, however, we noted a massive but compound-unspecific slow-down of endocytosis. This corresponded with a down-regulation of endocytosis by Rho-GTPases, previously identified to be intimately involved in endocytic traffic. In fact, we found endocytic internalization to relate with active Rho-A; vice versa, MDCK cell density, degree of cellular differentiation and endocytic slow-down were found to relate with active Rac-1. To our knowledge, this is the first study to cast light on the previously observed differentiation restricted internalization of CPPs into epithelial cell models. In the inflammatory IFN-gamma/TNF-alphaa induced confluent MDCK model mimicking inflammatory epithelial pathologies, CPP internalization was enhanced in a cytokine concentration-dependent way resulting in maximum enhancement rates of up to 90%. We suggest a cytokine induced redistribution of lipid rafts in confluent MDCK to cause this enhancement. CONCLUSION Our findings emphasize the significance of differentiated cell models in the study of CPP internalization and point towards inflammatory epithelial pathologies as potential niche for the application of CPPs for cellular delivery.
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Affiliation(s)
- Christina Foerg
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
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19
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Menotta M, Amicucci A, Basili G, Rivero F, Polidori E, Sisti D, Stocchi V. Molecular characterisation of the small GTPase CDC42 in the ectomycorrhizal fungus Tuber borchii Vittad. PROTOPLASMA 2007; 231:227-37. [PMID: 17762910 DOI: 10.1007/s00709-007-0254-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Accepted: 11/23/2006] [Indexed: 05/17/2023]
Abstract
The small GTPase CDC42 is ubiquitously expressed in eukaryotes, where it participates in the regulation of the cytoskeleton and a wide range of cellular processes, including cytokinesis, gene expression, cell cycle progression, apoptosis, and tumorigenesis. As very little is known on the molecular level about mycorrhizal morphogenesis and development and these events depend on a tightly regulated reorganisation of the cytoskeleton network in filamentous fungi, we focused on the molecular characterisation of the cdc42 gene in Tuber borchii Vittad., an ascomycetous hypogeous fungus forming ectomycorrhizae. The entire gene was isolated from a T. borchii cDNA library and Southern blot analyses showed that only one copy of cdc42 is present in the T. borchii genome. The predicted amino acid sequence is very similar to those of other known small GTPases and the similar domain structures suggest a similar function. Real-time PCR analyses revealed an increased expression of Tbcdc42 during the phase preparative to the instauration of symbiosis, in particular after stimulation with root exudate extracts. Immunolocalisation experiments revealed an accumulation of CDC42 in the apical tips of the growing hyphae. When a constitutively active Tbcdc42 mutant was expressed in Saccharomyces cerevisiae, morphological changes typical of pseudohyphal growth were observed. Our results suggest a fundamental role of CDC42 in cell polarity development in T. borchii.
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Affiliation(s)
- M Menotta
- Istituto di Chimica Biologica "G. Fornaini", Università degli Studi di Urbino, Urbino, Italy
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20
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Dawes AT, Edelstein-Keshet L. Phosphoinositides and Rho proteins spatially regulate actin polymerization to initiate and maintain directed movement in a one-dimensional model of a motile cell. Biophys J 2006; 92:744-68. [PMID: 17098793 PMCID: PMC1779977 DOI: 10.1529/biophysj.106.090514] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Gradient sensing, polarization, and chemotaxis of motile cells involve the actin cytoskeleton, and regulatory modules, including the phosphoinositides (PIs), their kinases/phosphatases, and small GTPases (Rho proteins). Here we model their individual components (PIP1, PIP2, PIP3; PTEN, PI3K, PI5K; Cdc42, Rac, Rho; Arp2/3, and actin), their interconversions, interactions, and modular functions in the context of a one-dimensional dynamic model for protrusive cell motility, with parameter values derived from in vitro and in vivo studies. In response to a spatially graded stimulus, the model produces stable amplified internal profiles of regulatory components, and initiates persistent motility (consistent with experimental observations). By connecting the modules, we find that Rho GTPases work as a spatial switch, and that the PIs filter noise, and define the front versus back. Relatively fast PI diffusion also leads to selection of a unique pattern of Rho distribution from a collection of possible patterns. We use the model to explore the importance of specific hypothesized interactions, to explore mutant phenotypes, and to study the role of actin polymerization in the maintenance of the PI asymmetry. We also suggest a mechanism to explain the spatial exclusion of Cdc42 and PTEN and the inability of cells lacking active Cdc42 to properly detect chemoattractant gradients.
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Affiliation(s)
- Adriana T Dawes
- Institute of Applied Mathematics and Department of Mathematics, University of British Columbia, Vancouver, British Columbia, Canada.
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21
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Boureux A, Vignal E, Faure S, Fort P. Evolution of the Rho family of ras-like GTPases in eukaryotes. Mol Biol Evol 2006; 24:203-16. [PMID: 17035353 PMCID: PMC2665304 DOI: 10.1093/molbev/msl145] [Citation(s) in RCA: 306] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
GTPases of the Rho family are molecular switches that play important roles in converting and amplifying external signals into cellular effects. Originally demonstrated to control the dynamics of the F-actin cytoskeleton, Rho GTPases have been implicated in many basic cellular processes that influence cell proliferation, differentiation, motility, adhesion, survival, or secretion. To elucidate the evolutionary history of the Rho family, we have analyzed over 20 species covering major eukaryotic clades from unicellular organisms to mammals, including platypus and opossum, and have reconstructed the ontogeny and the chronology of emergence of the different subfamilies. Our data establish that the 20 mammalian Rho members are structured into 8 subfamilies, among which Rac is the founder of the whole family. Rho, Cdc42, RhoUV, and RhoBTB subfamilies appeared before Coelomates and RhoJQ, Cdc42 isoforms, RhoDF, and Rnd emerged in chordates. In vertebrates, gene duplications and retrotranspositions increased the size of each chordate Rho subfamily, whereas RhoH, the last subfamily, arose probably by horizontal gene transfer. Rac1b, a Rac1 isoform generated by alternative splicing, emerged in amniotes, and RhoD, only in therians. Analysis of Rho mRNA expression patterns in mouse tissues shows that recent subfamilies have tissue-specific and low-level expression that supports their implication only in narrow time windows or in differentiated metabolic functions. These findings give a comprehensive view of the evolutionary canvas of the Rho family and provide guides for future structure and evolution studies of other components of Rho signaling pathways, in particular regulators of the RhoGEF family.
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Affiliation(s)
| | | | | | - Philippe Fort
- * Correspondence should be adressed to: Philippe Fort
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22
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Han JW, Leeper L, Rivero F, Chung CY. Role of RacC for the regulation of WASP and phosphatidylinositol 3-kinase during chemotaxis of Dictyostelium. J Biol Chem 2006; 281:35224-34. [PMID: 16968699 PMCID: PMC2853593 DOI: 10.1074/jbc.m605997200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
WASP family proteins are key players for connecting multiple signaling pathways to F-actin polymerization. To dissect the highly integrated signaling pathways controlling WASP activity, we identified a Rac protein that binds to the GTPase binding domain of WASP. Using two-hybrid and FRET-based functional assays, we identified RacC as a major regulator of WASP. RacC stimulates F-actin assembly in cell-free systems in a WASP-dependent manner. A FRET-based microscopy approach showed local activation of RacC at the leading edge of chemotaxing cells. Cells overexpressing RacC exhibit a significant increase in the level of F-actin polymerization upon cAMP stimulation, which can be blocked by a phosphatidylinositol (PI) 3-kinase inhibitor. Membrane translocation of PI 3-kinase and PI 3,4,5-trisphosphate reporter is absent in racC null cells. Cells overexpressing dominant negative RacC mutants and racC null cells move at a significantly slower speed and show a poor directionality during chemotaxis. Our results suggest that RacC plays an important role in PI 3-kinase activation and WASP activation for dynamic regulation of F-actin assembly during Dictyostelium chemotaxis.
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Affiliation(s)
- Ji W. Han
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6600
| | - Laura Leeper
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6600
| | - Francisco Rivero
- Zentrum für Biochemie and Zentrum für Molekulare Medizin, Medizinische Fakultät, Universität zu Köln, Joseph-Stelzmann-Strasse 52, 50931 Köln, Germany
| | - Chang Y. Chung
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6600
- To whom correspondence should be addressed: 468 Robinson Research Bldg. (MRB I), 1215 21st Ave. South at Pierce, Nashville, TN 37232-6600. Tel.: 615-322-4956; Fax: 615-343-6532;
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23
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Somesh BP, Vlahou G, Iijima M, Insall RH, Devreotes P, Rivero F. RacG regulates morphology, phagocytosis, and chemotaxis. EUKARYOTIC CELL 2006; 5:1648-63. [PMID: 16950926 PMCID: PMC1595345 DOI: 10.1128/ec.00221-06] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
RacG is an unusual member of the complex family of Rho GTPases in Dictyostelium. We have generated a knockout (KO) strain, as well as strains that overexpress wild-type (WT), constitutively active (V12), or dominant negative (N17) RacG. The protein is targeted to the plasma membrane, apparently in a nucleotide-dependent manner, and induces the formation of abundant actin-driven filopods. RacG is enriched at the rim of the progressing phagocytic cup, and overexpression of RacG-WT or RacG-V12 induced an increased rate of particle uptake. The positive effect of RacG on phagocytosis was abolished in the presence of 50 microM LY294002, a phosphoinositide 3-kinase inhibitor, indicating that generation of phosphatidylinositol 3,4,5-trisphosphate is required for activation of RacG. RacG-KO cells showed a moderate chemotaxis defect that was stronger in the RacG-V12 and RacG-N17 mutants, in part because of interference with signaling through Rac1. The in vivo effects of RacG-V12 could not be reproduced by a mutant lacking the Rho insert region, indicating that this region is essential for interaction with downstream components. Processes like growth, pinocytosis, exocytosis, cytokinesis, and development were unaffected in Rac-KO cells and in the overexpressor mutants. In a cell-free system, RacG induced actin polymerization upon GTPgammaS stimulation, and this response could be blocked by an Arp3 antibody. While the mild phenotype of RacG-KO cells indicates some overlap with one or more Dictyostelium Rho GTPases, like Rac1 and RacB, the significant changes found in overexpressors show that RacG plays important roles. We hypothesize that RacG interacts with a subset of effectors, in particular those concerned with shape, motility, and phagocytosis.
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Affiliation(s)
- Baggavalli P Somesh
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Strasse 52, D-50931 Cologne, Germany
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24
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Vlahou G, Rivero F. Rho GTPase signaling in Dictyostelium discoideum: Insights from the genome. Eur J Cell Biol 2006; 85:947-59. [PMID: 16762450 DOI: 10.1016/j.ejcb.2006.04.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Rho GTPases are ubiquitously expressed across the eukaryotes where they act as molecular switches participating in the regulation of many cellular processes. We present an inventory of proteins involved in Rho-regulated signaling pathways in Dictyostelium discoideum that have been identified in the completed genome sequence. In Dictyostelium the Rho family is encoded by 18 genes and one pseudogene. Some of the Rho GTPases (Rac1a/b/c, RacF1/F2 and RacB) are members of the Rac subfamily, and one, RacA, belongs to the RhoBTB subfamily. The Cdc42 and Rho subfamilies, characteristic of metazoa and fungi, are absent. The activities of these GTPases are regulated by two members of the RhoGDI family, by eight members of the Dock180/zizimin family and by a surprisingly large number of proteins carrying RhoGEF (42 genes) or RhoGAP (43 genes) domains or both (three genes). Most of these show domain compositions not found in other organisms, although some have clear homologs in metazoa and/or fungi. Among the (in many cases putative) effectors found in Dictyostelium are the CRIB domain proteins (WASP and two related proteins, eight PAK kinases and a novel gelsolin-related protein), components of the Scar/WAVE complex, 10 formins, four IQGAPs, two members of the PCH family, numerous lipid kinases and phospholipases, and components of the NADPH oxidase and the exocyst complexes. In general, the repertoire of Rho signaling components of Dictyostelium is similar to that of metazoa and fungi.
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Affiliation(s)
- Georgia Vlahou
- Center for Biochemistry of the Medical Faculty and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, D-50931 Cologne, Germany
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25
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Brembu T, Winge P, Bones AM, Yang Z. A RHOse by any other name: a comparative analysis of animal and plant Rho GTPases. Cell Res 2006; 16:435-45. [PMID: 16699539 DOI: 10.1038/sj.cr.7310055] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Rho GTPases are molecular switches that act as key regulators of a many cellular processes, including cell movement, morphogenesis, host defense, cell division and gene expression. Rho GTPases are found in all eukaryotic kingdoms. Plants lack clear homologs to conventional Rho GTPases found in yeast and animals; instead, they have over time developed a unique subfamily, ROPs, also known as RAC. The origin of ROP-like proteins appears to precede the appearance of land plants. This review aims to discuss the evolution of ROP/RAC and to compare plant ROP and animal Rho GTPases, focusing on similarities and differences in regulation of the GTPases and their downstream effectors.
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Affiliation(s)
- Tore Brembu
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute of Integrative Genome Biology, University of California, Riverside, California 92521, USA
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26
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Muramoto T, Urushihara H. Small GTPase RacF2 affects sexual cell fusion and asexual development in Dictyostelium discoideum through the regulation of cell adhesion. Dev Growth Differ 2006; 48:199-208. [PMID: 16573737 DOI: 10.1111/j.1440-169x.2006.00857.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cells of Dictyostelium discoideum become sexually mature when submerged and in darkness, and fuse with opposite mating-type cells as gametes. The gene for a Rho GTPase, RacF2, is one of the extremely gamete-enriched genes (>100-fold) identified by us previously. Here, we isolated knockout, overexpression, constitutively active and dominant negative mutants of RacF2, and analyzed their phenotypes. These mutants showed anomalies in the extent of sexual cell fusion and asexual development as well as in EDTA-sensitive cell-cell adhesion. It is suggested that RacF2 controls the process of sexual and asexual development through the regulation of cellular adhesiveness. An analysis of the expression of all 18 rac family genes by real-time polymerase chain reaction revealed that four additional genes, rac1b, rac1c, racF1 and racG, were induced during maturation, suggesting their possible involvement in sexual cell interactions.
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Affiliation(s)
- Tetsuya Muramoto
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
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27
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Somesh BP, Neffgen C, Iijima M, Devreotes P, Rivero F. Dictyostelium RacH Regulates Endocytic Vesicular Trafficking and is Required for Localization of Vacuolin. Traffic 2006; 7:1194-212. [PMID: 17004322 DOI: 10.1111/j.1600-0854.2006.00455.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Dictyostelium RacH localizes predominantly to membranes of the nuclear envelope, endoplasmic reticulum and Golgi apparatus. To investigate the role of this protein, we generated knockout and overexpressor strains. RacH-deficient cells displayed 50% reduced fluid-phase uptake and a moderate exocytosis defect, but phagocytosis was unaffected. Detailed examination of the endocytic pathway revealed defective acidification of early endosomes and reduced secretion of acid phosphatase in the presence of sucrose. The distribution of the post-lysosomal marker vacuolin was altered, with a high proportion of cells showing a diffuse vesicular pattern in contrast to the wild-type strain, where few intensely stained vacuoles predominate. Cytokinesis, cell motility, chemotaxis and development appeared largely unaffected. In a cell-free system, RacH stimulates actin polymerization, suggesting that this protein is involved in actin-based trafficking of vesicular compartments. We also investigated the determinants of subcellular localization of RacH by expression of green-fluorescent-protein-tagged chimeras in which the C-terminus of RacH and the plasma-membrane-targeted RacG were exchanged, the insert region was deleted or the net positive charge of the hypervariable region was increased. We show that several regions of the molecule, not only the hypervariable region, determine targeting of RacH. Overexpression of mistargeted RacH mutants did not recapitulate the phenotypes of a strain overexpressing nonmutated RacH, indicating that the function of this protein is in great part related to its subcellular localization.
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Affiliation(s)
- Baggavalli P Somesh
- Center for Biochemistry, Medical Faculty, University of Cologne, D-50931 Köln, Germany
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28
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Sasaki AT, Firtel RA. Regulation of chemotaxis by the orchestrated activation of Ras, PI3K, and TOR. Eur J Cell Biol 2006; 85:873-95. [PMID: 16740339 DOI: 10.1016/j.ejcb.2006.04.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Directed cell migration and cell polarity are crucial in many facets of biological processes. Cellular motility requires a complex array of signaling pathways, in which orchestrated cross-talk, a feedback loop, and multi-component signaling recur. Almost every signaling molecule requires several regulatory processes to be functionally activated, and a lack of a signaling molecule often leads to chemotaxis defects, suggesting an integral role for each component in the pathway. We outline our current understanding of the signaling event that regulates chemotaxis with an emphasis on recent findings associated with the Ras, PI3K, and target of rapamycin (TOR) pathways and the interplay of these pathways. Ras, PI3K, and TOR are known as key regulators of cellular growth. Deregulation of those pathways is associated with many human diseases, such as cancer, developmental disorders, and immunological deficiency. Recent studies in yeast, mammalian cells, and Dictyostelium discoideum reveal another critical role of Ras, PI3K, and TOR in regulating the actin cytoskeleton, cell polarity, and cellular movement. These findings shed light on the mechanism by which eukaryotic cells maintain cell polarity and directed cell movement, and also demonstrate that multiple steps in the signal transduction pathway coordinately regulate cell motility.
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Affiliation(s)
- Atsuo T Sasaki
- Section of Cell and Developmental Biology, Division of Biological Sciences, Center for Molecular Genetics, University of California, San Diego, Natural Sciences Building, Room 6316, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA
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29
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De Melo LDB, Eisele N, Nepomuceno-Silva JL, Lopes UG. TcRho1, the Trypanosoma cruzi Rho homologue, regulates cell-adhesion properties: Evidence for a conserved function. Biochem Biophys Res Commun 2006; 345:617-22. [PMID: 16690023 DOI: 10.1016/j.bbrc.2006.04.075] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Accepted: 04/17/2006] [Indexed: 10/24/2022]
Abstract
Rho proteins are members of the Ras superfamily of small GTPases. In higher eukaryotes these proteins play pivotal role in cell movement, phagocytosis, intracellular transport, cell-adhesion, and maintenance of cell morphology, mainly through the regulation of actin microfilaments. The GTPase TcRho1 is the only member of the Rho family described in human protozoan parasite Trypanosoma cruzi. We previously demonstrated that TcRho1 is actually required for differentiation of epimastigote to trypomastigote forms during the parasite cell cycle. In the present work, we describe cellular phenotypes induced by TcRho1 heterologous expression in NIH 3T3 fibroblasts. The NIH-3T3 lineages expressing the TcRho1-G15V and TcRho1-Q76L mutants displayed decreased levels of migration compared to the control lineage NIH-3T3 pcDNA3.1, a phenotype probably due to distinct cell-substrate adhesion properties expressed by the mutant cell lines. Accordingly, cell-substrate adhesion assays revealed that the mutant cell lines of NIH-3T3 expressing TcRho1-positive dominants constructions present enhanced substrate-adhesion phenotype. Furthermore, similar experiments with T. cruzi expressing TcRho1 mutants also revealed an enhancement of cell attachment. These results suggest that TcRho1 plays a conserved regulatory role in cell-substrate adhesion in both NIH-3T3 fibroblasts and T. cruzi epimastigotes. Taken together, our data corroborate the notion that TcRho1 may regulate the substrate-adhesion in T. cruzi, a critical step for successful progression of the parasite life cycle.
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Affiliation(s)
- Luiz Dione Barbosa De Melo
- Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, CCS, UFRJ, Rio de Janeiro, Brazil
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30
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Pikzack C, Prassler J, Furukawa R, Fechheimer M, Rivero F. Role of calcium-dependent actin-bundling proteins: characterization of Dictyostelium mutants lacking fimbrin and the 34-kilodalton protein. ACTA ACUST UNITED AC 2006; 62:210-31. [PMID: 16265631 DOI: 10.1002/cm.20098] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Actin-bundling proteins organize actin filaments into densely packed bundles. In Dictyostelium discoideum two abundant proteins display calcium-regulated bundling activity, fimbrin and the 34-kDa protein (ABP34). Using a GFP fusion we observed transient localization of fimbrin at the phagocytic cup and macropinosomes. The distribution of truncated constructs encompassing the EF hands and the first actin-binding domain (EA1) or both actin-binding domains devoid of EF hands (A1A2) was indistinguishable from that of the full length protein. The role of fimbrin and a possible functional overlap with ABP34 was investigated in fim- and double 34-/fim- mutants. Except for a moderate cell size defect, fim- mutants did not show defects in growth, endocytosis, exocytosis, and chemotaxis. Double mutants were characterized by a small cell size and a defect in morphogenesis resulting in small fruiting bodies and a low spore yield. The cell size defect could not be overcome by expression of fimbrin fragments EA1 or A1A2, suggesting that both bundling activity and regulation by calcium are important. Induction of filopod formation in 34-/fim- cells was not impaired, indicating that both proteins are dispensable for this process. We searched in the Dictyostelium genome database for fimbrin-like proteins that could compensate for the fimbrin defect and identified three unconventional fimbrins and two more proteins with actin-binding domains of the type present in fimbrins.
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Affiliation(s)
- Claudia Pikzack
- Zentrum für Biochemie, Medizinische Fakultät, Universität zu Köln, Köln, Germany
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Abstract
The Rho family of small GTPases are important regulators of multiple cellular activities and, most notably, reorganization of the actin cytoskeleton. Dbl-homology (DH)-domain-containing proteins are the classical guanine nucleotide exchange factors (GEFs) responsible for activation of Rho GTPases. However, members of a newly discovered family can also act as Rho-GEFs. These CZH proteins include: CDM (Ced-5, Dock180 and Myoblast city) proteins, which activate Rac; and zizimin proteins, which activate Cdc42. The family contains 11 mammalian proteins and has members in many other eukaryotes. The GEF activity is carried out by a novel, DH-unrelated domain named the DOCKER, CZH2 or DHR2 domain. CZH proteins have been implicated in cell migration, phagocytosis of apoptotic cells, T-cell activation and neurite outgrowth, and probably arose relatively early in eukaryotic evolution.
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Affiliation(s)
- Nahum Meller
- Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA.
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32
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Abstract
We review insights in signaling pathways controlling cell polarization and cytoskeletal organization during chemotactic movement in Dictyostelium amoebae and neutrophils. We compare and contrast these insights with our current understanding of pathways controlling chemotactic movements in more-complex multicellular developmental contexts.
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Affiliation(s)
- Markus Affolter
- Department of Cell Biology, Biozentrum University of Basel, Klingelbergstr. 70, CH-4056 Basel, Switzerland
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33
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Eichinger L, Pachebat J, Glöckner G, Rajandream MA, Sucgang R, Berriman M, Song J, Olsen R, Szafranski K, Xu Q, Tunggal B, Kummerfeld S, Madera M, Konfortov BA, Rivero F, Bankier AT, Lehmann R, Hamlin N, Davies R, Gaudet P, Fey P, Pilcher K, Chen G, Saunders D, Sodergren E, Davis P, Kerhornou A, Nie X, Hall N, Anjard C, Hemphill L, Bason N, Farbrother P, Desany B, Just E, Morio T, Rost R, Churcher C, Cooper J, Haydock S, van Driessche N, Cronin A, Goodhead I, Muzny D, Mourier T, Pain A, Lu M, Harper D, Lindsay R, Hauser H, James K, Quiles M, Babu MM, Saito T, Buchrieser C, Wardroper A, Felder M, Thangavelu M, Johnson D, Knights A, Loulseged H, Mungall K, Oliver K, Price C, Quail M, Urushihara H, Hernandez J, Rabbinowitsch E, Steffen D, Sanders M, Ma J, Kohara Y, Sharp S, Simmonds M, Spiegler S, Tivey A, Sugano S, White B, Walker D, Woodward J, Winckler T, Tanaka Y, Shaulsky G, Schleicher M, Weinstock G, Rosenthal A, Cox E, Chisholm RL, Gibbs R, Loomis WF, Platzer M, Kay RR, Williams J, Dear PH, Noegel AA, Barrell B, Kuspa A. The genome of the social amoeba Dictyostelium discoideum. Nature 2005; 435:43-57. [PMID: 15875012 PMCID: PMC1352341 DOI: 10.1038/nature03481] [Citation(s) in RCA: 958] [Impact Index Per Article: 50.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Accepted: 02/17/2005] [Indexed: 02/07/2023]
Abstract
The social amoebae are exceptional in their ability to alternate between unicellular and multicellular forms. Here we describe the genome of the best-studied member of this group, Dictyostelium discoideum. The gene-dense chromosomes of this organism encode approximately 12,500 predicted proteins, a high proportion of which have long, repetitive amino acid tracts. There are many genes for polyketide synthases and ABC transporters, suggesting an extensive secondary metabolism for producing and exporting small molecules. The genome is rich in complex repeats, one class of which is clustered and may serve as centromeres. Partial copies of the extrachromosomal ribosomal DNA (rDNA) element are found at the ends of each chromosome, suggesting a novel telomere structure and the use of a common mechanism to maintain both the rDNA and chromosomal termini. A proteome-based phylogeny shows that the amoebozoa diverged from the animal-fungal lineage after the plant-animal split, but Dictyostelium seems to have retained more of the diversity of the ancestral genome than have plants, animals or fungi.
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Affiliation(s)
- L. Eichinger
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - J.A. Pachebat
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - G. Glöckner
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - M.-A. Rajandream
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - R. Sucgang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - M. Berriman
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - J. Song
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - R. Olsen
- Section of Cell and Developmental Biology, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - K. Szafranski
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - Q. Xu
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston TX 77030, USA
| | - B. Tunggal
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - S. Kummerfeld
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - M. Madera
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - B. A. Konfortov
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - F. Rivero
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - A. T. Bankier
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - R. Lehmann
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - N. Hamlin
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - R. Davies
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - P. Gaudet
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - P. Fey
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - K. Pilcher
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - G. Chen
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - D. Saunders
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - E. Sodergren
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - P. Davis
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Kerhornou
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - X. Nie
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - N. Hall
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - C. Anjard
- Section of Cell and Developmental Biology, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - L. Hemphill
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - N. Bason
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - P. Farbrother
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - B. Desany
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - E. Just
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - T. Morio
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - R. Rost
- Adolf-Butenandt-Institute/Cell Biology, Ludwig-Maximilians-University, 80336 Munich, Germany
| | - C. Churcher
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - J. Cooper
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - S. Haydock
- Biochemistry Department, University of Cambridge, Cambridge CB2 1QW, UK
| | - N. van Driessche
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - A. Cronin
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - I. Goodhead
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - D. Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - T. Mourier
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Pain
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - M. Lu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - D. Harper
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - R. Lindsay
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - H. Hauser
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - K. James
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - M. Quiles
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - M. Madan Babu
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - T. Saito
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810 Japan
| | - C. Buchrieser
- Unité de Genomique des Microorganismes Pathogenes, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France
| | - A. Wardroper
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
- Department of Biology, University of York, York YO10 5YW, UK
| | - M. Felder
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - M. Thangavelu
- MRC Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 2XZ, UK
| | - D. Johnson
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Knights
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - H. Loulseged
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - K. Mungall
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - K. Oliver
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - C. Price
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - M.A. Quail
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - H. Urushihara
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - J. Hernandez
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - E. Rabbinowitsch
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - D. Steffen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - M. Sanders
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - J. Ma
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Y. Kohara
- Centre for Genetic Resource Information, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - S. Sharp
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - M. Simmonds
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - S. Spiegler
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Tivey
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - S. Sugano
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Minato, Tokyo 108-8639, Japan
| | - B. White
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - D. Walker
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - J. Woodward
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - T. Winckler
- Institut für Pharmazeutische Biologie, Universität Frankfurt (Biozentrum), Frankfurt am Main, 60439, Germany
| | - Y. Tanaka
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - G. Shaulsky
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston TX 77030, USA
| | - M. Schleicher
- Adolf-Butenandt-Institute/Cell Biology, Ludwig-Maximilians-University, 80336 Munich, Germany
| | - G. Weinstock
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - A. Rosenthal
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - E.C. Cox
- Department of Molecular Biology, Princeton University, Princeton, NJ08544-1003, USA
| | - R. L. Chisholm
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - R. Gibbs
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - W. F. Loomis
- Section of Cell and Developmental Biology, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - M. Platzer
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - R. R. Kay
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - J. Williams
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - P. H. Dear
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - A. A. Noegel
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - B. Barrell
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Kuspa
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Rivero F, Muramoto T, Meyer AK, Urushihara H, Uyeda TQP, Kitayama C. A comparative sequence analysis reveals a common GBD/FH3-FH1-FH2-DAD architecture in formins from Dictyostelium, fungi and metazoa. BMC Genomics 2005; 6:28. [PMID: 15740615 PMCID: PMC555941 DOI: 10.1186/1471-2164-6-28] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Accepted: 03/01/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Formins are multidomain proteins defined by a conserved FH2 (formin homology 2) domain with actin nucleation activity preceded by a proline-rich FH1 (formin homology 1) domain. Formins act as profilin-modulated processive actin nucleators conserved throughout a wide range of eukaryotes. RESULTS We present a detailed sequence analysis of the 10 formins (ForA to J) identified in the genome of the social amoeba Dictyostelium discoideum. With the exception of ForI and ForC all other formins conform to the domain structure GBD/FH3-FH1-FH2-DAD, where DAD is the Diaphanous autoinhibition domain and GBD/FH3 is the Rho GTPase-binding domain/formin homology 3 domain that we propose to represent a single domain. ForC lacks a FH1 domain, ForI lacks recognizable GBD/FH3 and DAD domains and ForA, E and J have additional unique domains. To establish the relationship between formins of Dictyostelium and other organisms we constructed a phylogenetic tree based on the alignment of FH2 domains. Real-time PCR was used to study the expression pattern of formin genes. Expression of forC, D, I and J increased during transition to multi-cellular stages, while the rest of genes displayed less marked developmental variations. During sexual development, expression of forH and forI displayed a significant increase in fusion competent cells. CONCLUSION Our analysis allows some preliminary insight into the functionality of Dictyostelium formins: all isoforms might display actin nucleation activity and, with the exception of ForI, might also be susceptible to autoinhibition and to regulation by Rho GTPases. The architecture GBD/FH3-FH1-FH2-DAD appears common to almost all Dictyostelium, fungal and metazoan formins, for which we propose the denomination of conventional formins, and implies a common regulatory mechanism.
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Affiliation(s)
- Francisco Rivero
- Center for Biochemistry and Center for Molecular Medicine, Medical Faculty, University of Cologne. Joseph-Stelzmann-Strasse 52, 50931 Köln, Germany
| | - Tetsuya Muramoto
- Institute of Biological Science, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan
| | - Ann-Kathrin Meyer
- Center for Biochemistry and Center for Molecular Medicine, Medical Faculty, University of Cologne. Joseph-Stelzmann-Strasse 52, 50931 Köln, Germany
| | - Hideko Urushihara
- Institute of Biological Science, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan
| | - Taro QP Uyeda
- Gene Function Research Center, Tsukuba Central #4, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1 Tsukuba-shi, Ibaraki 305-8562, Japan
| | - Chikako Kitayama
- Gene Function Research Center, Tsukuba Central #4, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1 Tsukuba-shi, Ibaraki 305-8562, Japan
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Abstract
Dictyostelium is an accessible organism for studies of signaling via chemoattractant receptors. Chemoattractant-mediated signaling events and components are reviewed and presented as a series of connected modules, including excitation, inhibition, G protein-independent responses, early gene expression, inositol lipids, PH domain-containing proteins, cyclic AMP signaling, polarization acquisition, actin polymerization, and cortical myosin. The network incorporates information from biochemical, genetic, and cell biological experiments carried out on living cells. The modules and connections represent current understanding, and future information is expected to modify and build upon this structure.
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Affiliation(s)
- Carol L Manahan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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de la Roche M, Mahasneh A, Lee SF, Rivero F, Côté GP. Cellular distribution and functions of wild-type and constitutively activated Dictyostelium PakB. Mol Biol Cell 2004; 16:238-47. [PMID: 15509655 PMCID: PMC539168 DOI: 10.1091/mbc.e04-06-0534] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Dictyostelium PakB, previously termed myosin I heavy chain kinase, is a member of the p21-activated kinase (PAK) family. Two-hybrid assays showed that PakB interacts with Dictyostelium Rac1a/b/c, RacA (a RhoBTB protein), RacB, RacC, and RacF1. Wild-type PakB displayed a cytosolic distribution with a modest enrichment at the leading edge of migrating cells and at macropinocytic and phagocytic cups, sites consistent with a role in activating myosin I. PakB fused at the N terminus to green fluorescent protein was proteolyzed in cells, resulting in removal of the catalytic domain. C-terminal truncated PakB and activated PakB lacking the p21-binding domain strongly localized to the cell cortex, to macropinocytic cups, to the posterior of migrating cells, and to the cleavage furrow of dividing cells. These data indicate that in its open, active state, the N terminus of PakB forms a tight association with cortical actin filaments. PakB-null cells displayed no significant behavioral defects, but cells expressing activated PakB were unable to complete cytokinesis when grown in suspension and exhibited increased rates of phagocytosis and pinocytosis.
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Affiliation(s)
- Marc de la Roche
- Department of Biochemistry, Queen's University, Kingston, Ontario, Canada
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Park KC, Rivero F, Meili R, Lee S, Apone F, Firtel RA. Rac regulation of chemotaxis and morphogenesis in Dictyostelium. EMBO J 2004; 23:4177-89. [PMID: 15470506 PMCID: PMC524383 DOI: 10.1038/sj.emboj.7600368] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2004] [Accepted: 07/27/2004] [Indexed: 12/22/2022] Open
Abstract
Chemotaxis requires localized F-actin polymerization at the site of the plasma membrane closest to the chemoattractant source, a process controlled by Rac/Cdc42 GTPases. We identify Dictyostelium RacB as an essential mediator of this process. RacB is activated upon chemoattractant stimulation, exhibiting biphasic kinetics paralleling F-actin polymerization. racB null cells have strong chemotaxis and morphogenesis defects and a severely reduced chemoattractant-mediated F-actin polymerization and PAKc activation. RacB activation is partly controlled by the PI3K pathway. pi3k1/2 null cells and wild-type cells treated with LY294002 exhibit a significantly reduced second peak of RacB activation, which is linked to pseudopod extension, whereas a PTEN hypomorph exhibits elevated RacB activation. We identify a RacGEF, RacGEF1, which has specificity for RacB in vitro. racgef1 null cells exhibit reduced RacB activation and cells expressing mutant RacGEF1 proteins display chemotaxis and morphogenesis defects. RacGEF1 localizes to sites of F-actin polymerization. Inhibition of this localization reduces RacB activation, suggesting a feedback loop from RacB via F-actin polymerization to RacGEF1. Our findings provide a critical linkage between chemoattractant stimulation, F-actin polymerization, and chemotaxis in Dictyostelium.
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Affiliation(s)
- Kyung Chan Park
- Section of Cell and Developmental Biology, Division of Biological Sciences, Center for Molecular Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Francisco Rivero
- Zentrum für Biochemie der Medizinischen Fakultät, Universität zu Köln, Köln, Germany
| | - Ruedi Meili
- Section of Cell and Developmental Biology, Division of Biological Sciences, Center for Molecular Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Susan Lee
- Section of Cell and Developmental Biology, Division of Biological Sciences, Center for Molecular Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Fabio Apone
- Section of Cell and Developmental Biology, Division of Biological Sciences, Center for Molecular Genetics, University of California, San Diego, La Jolla, CA, USA
| | - Richard A Firtel
- Section of Cell and Developmental Biology, Division of Biological Sciences, Center for Molecular Genetics, University of California, San Diego, La Jolla, CA, USA
- University of California, Natural Sciences Building, Room 6316, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA. Tel.: +1 858 534 2788; Fax: +1 858 822 5900; E-mail:
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Uyeda TQP, Nagasaki A, Yumura S. Multiple Parallelisms in Animal Cytokinesis. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 240:377-432. [PMID: 15548417 DOI: 10.1016/s0074-7696(04)40004-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The process of cytokinesis in animal cells is usually presented as a relatively simple picture: A cleavage plane is first positioned in the equatorial region by the astral microtubules of the anaphase mitotic apparatus, and a contractile ring made up of parallel filaments of actin and myosin II is formed and encircles the cortex at the division site. Active sliding between the two filament systems constricts the perimeter of the cortex, leading to separation of two daughter cells. However, recent studies in both animal cells and lower eukaryotic model organisms have demonstrated that cytokinesis is actually far more complex. It is now obvious that the three key processes of cytokinesis, cleavage plane determination, equatorial furrowing, and scission, are driven by different mechanisms in different types of cells. In some cases, moreover, multiple pathways appear to have redundant functions in a single cell type. In this review, we present a novel hypothesis that incorporates recent observations on the activities of mitotic microtubules and the biochemistry of Rho-type GTPase proteins and postulates that two different sets of microtubules are responsible for the two known mechanisms of cleavage plane determination and also for two distinct mechanisms of equatorial furrowing.
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Affiliation(s)
- Taro Q P Uyeda
- Gene Function Research Center, National Institute for Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
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