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Rangel L, Bernabé-Rubio M, Fernández-Barrera J, Casares-Arias J, Millán J, Alonso MA, Correas I. Caveolin-1α regulates primary cilium length by controlling RhoA GTPase activity. Sci Rep 2019; 9:1116. [PMID: 30718762 PMCID: PMC6362014 DOI: 10.1038/s41598-018-38020-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 10/26/2018] [Indexed: 11/08/2022] Open
Abstract
The primary cilium is a single non-motile protrusion of the plasma membrane of most types of mammalian cell. The structure, length and function of the primary cilium must be tightly controlled because their dysfunction is associated with disease. Caveolin 1 (Cav1), which is best known as a component of membrane invaginations called caveolae, is also present in non-caveolar membrane domains whose function is beginning to be understood. We show that silencing of α and β Cav1 isoforms in different cell lines increases ciliary length regardless of the route of primary ciliogenesis. The sole expression of Cav1α, which is distributed at the apical membrane, restores normal cilium size in Cav1 KO MDCK cells. Cells KO for only Cav1α, which also show long cilia, have a disrupted actin cytoskeleton and reduced RhoA GTPase activity at the apical membrane, and a greater accumulation of Rab11 vesicles at the centrosome. Subsequent experiments showed that DIA1 and ROCK help regulate ciliary length. Since MDCK cells lack apical caveolae, our results imply that non-caveolar apical Cav1α is an important regulator of ciliary length, exerting its effect via RhoA and its effectors, ROCK and DIA1.
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Affiliation(s)
- Laura Rangel
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
- Department of Molecular Biology, Universidad Autónoma de Madrid, Madrid, Spain
| | - Miguel Bernabé-Rubio
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Jaime Fernández-Barrera
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Javier Casares-Arias
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Jaime Millán
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Miguel A Alonso
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain.
| | - Isabel Correas
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain.
- Department of Molecular Biology, Universidad Autónoma de Madrid, Madrid, Spain.
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2
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Calvert SJ, Longtine MS, Cotter S, Jones CJP, Sibley CP, Aplin JD, Nelson DM, Heazell AEP. Studies of the dynamics of nuclear clustering in human syncytiotrophoblast. Reproduction 2016; 151:657-71. [PMID: 27002000 PMCID: PMC4911178 DOI: 10.1530/rep-15-0544] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/21/2016] [Indexed: 11/29/2022]
Abstract
Syncytial nuclear aggregates (SNAs), clusters of nuclei in the syncytiotrophoblast of
the human placenta, are increased as gestation advances and in pregnancy pathologies.
The origins of increased SNAs are unclear; however, a better appreciation of the
mechanism may give insight into placental ageing and factors underpinning
dysfunction. We developed three models to investigate whether SNA formation results
from a dynamic process of nuclear movement and to generate alternative hypotheses.
SNA count and size were measured in placental explants cultured over 16 days and
particles released into culture medium were quantified. Primary trophoblasts were
cultured for 6 days. Explants and trophoblasts were cultured with and without
cytoskeletal inhibitors. An in silico model was developed to examine
the effects of modulating nuclear behaviour on clustering. In explants, neither
median SNA number (108 SNA/mm2 villous area) nor size (283
μm2) changed over time. Subcellular particles from conditioned
culture medium showed a wide range of sizes that overlapped with those of SNAs.
Nuclei in primary trophoblasts did not change position relative to other nuclei;
apparent movement was associated with positional changes of the syncytial cell
membrane. In both models, SNAs and nuclear clusters were stable despite
pharmacological disruption of cytoskeletal activity. In silico,
increased nuclear movement, adhesiveness and sites of cytotrophoblast fusion were
related to nuclear clustering. The prominence of SNAs in pregnancy disorders may not
result from an active process involving cytoskeleton-mediated rearrangement of
syncytial nuclei. Further insights into the mechanism(s) of SNA formation will aid
understanding of their increased presence in pregnancy pathologies.
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Affiliation(s)
- S J Calvert
- Maternal and Fetal Health Research CentreInstitute of Human Development, School of Medicine, University of Manchester, Manchester, UK St Mary's HospitalCentral Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - M S Longtine
- Department of Obstetrics and GynecologyWashington University School of Medicine, St Louis, Missouri, USA
| | - S Cotter
- School of MathematicsAlan Turing Building, University of Manchester, Manchester, UK
| | - C J P Jones
- Maternal and Fetal Health Research CentreInstitute of Human Development, School of Medicine, University of Manchester, Manchester, UK St Mary's HospitalCentral Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - C P Sibley
- Maternal and Fetal Health Research CentreInstitute of Human Development, School of Medicine, University of Manchester, Manchester, UK St Mary's HospitalCentral Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - J D Aplin
- Maternal and Fetal Health Research CentreInstitute of Human Development, School of Medicine, University of Manchester, Manchester, UK St Mary's HospitalCentral Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - D M Nelson
- Department of Obstetrics and GynecologyWashington University School of Medicine, St Louis, Missouri, USA
| | - A E P Heazell
- Maternal and Fetal Health Research CentreInstitute of Human Development, School of Medicine, University of Manchester, Manchester, UK St Mary's HospitalCentral Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
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3
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George SP, Wang Y, Mathew S, Srinivasan K, Khurana S. Dimerization and actin-bundling properties of villin and its role in the assembly of epithelial cell brush borders. J Biol Chem 2007; 282:26528-41. [PMID: 17606613 DOI: 10.1074/jbc.m703617200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Villin is a major actin-bundling protein in the brush border of epithelial cells. In this study we demonstrate for the first time that villin can bundle actin filaments using a single F-actin binding site, because it has the ability to self-associate. Using fluorescence resonance energy transfer, we demonstrate villin self-association in living cells in microvilli and in growth factor-stimulated cells in membrane ruffles and lamellipodia. Using sucrose density gradient, size-exclusion chromatography, and matrix-assisted laser desorption ionization time-of-flight, the majority of villin was identified as a monomer or dimer. Villin dimers were also identified in Caco-2 cells, which endogenously express villin and Madin-Darby canine kidney cells that ectopically express villin. Using truncation mutants of villin, site-directed mutagenesis, and fluorescence resonance energy transfer, an amino-terminal dimerization site was identified that regulated villin self-association in parallel conformation as well as actin bundling by villin. This detailed analysis describes for the first time microvillus assembly by villin, redefines the actin-bundling function of villin, and provides a molecular mechanism for actin bundling by villin, which could have wider implications for other actin cross-linking proteins that share a villin-like headpiece domain. Our study also provides a molecular basis to separate the morphologically distinct actin-severing and actin-bundling properties of villin.
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Affiliation(s)
- Sudeep P George
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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4
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Rocheleau JV, Wiseman PW, Petersen NO. Isolation of bright aggregate fluctuations in a multipopulation image correlation spectroscopy system using intensity subtraction. Biophys J 2003; 84:4011-22. [PMID: 12770905 PMCID: PMC1302981 DOI: 10.1016/s0006-3495(03)75127-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Image correlation spectroscopy allows sensitive measurement of the spatial distribution and aggregation state of fluorescent membrane macro molecules. When studying a single population system (i.e., aggregates of similar brightness), an accurate measure can be made of the aggregate number per observation area, but this measurement becomes much more complex in a distributed population system (i.e., bright and faint aggregates). This article describes an alternate solution that involves extraction of the bright aggregate population information. This novel development for image correlation spectroscopy, termed intensity subtraction analysis, uses sequential uniform intensity subtraction from raw confocal images. Sequential intensity subtraction results in loss of faint aggregate fluctuations that are smaller in magnitude than fluctuations due to the brightest aggregates. The resulting image has correlatable fluctuations originating from only the brightest population, permitting quantification of this population's distribution and further cross-correlation measurements. The feasibility of this technique is demonstrated using fluorescent microsphere images and biological samples. The technique is further used to examine the spatial distribution of a plasma-membrane-labeled fluorescent synthetic ganglioside, and to cross-correlate this probe with various membrane markers. The evidence provided demonstrates that bright aggregates of the fluorescent ganglioside are associated with clathrin-coated pits, membrane microvilli, and detergent-resistant membranes.
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Affiliation(s)
- Jonathan V Rocheleau
- Department of Chemistry, Chemistry Building, University of Western Ontario, London, Ontario N6A 5B7, Canada
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5
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Sela S, Marouni MJ, Perry R, Barzilai A. Effect of lipoteichoic acid on the uptake of Streptococcus pyogenes by HEp-2 cells. FEMS Microbiol Lett 2000; 193:187-93. [PMID: 11111022 DOI: 10.1111/j.1574-6968.2000.tb09422.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Lipoteichoic acid (LTA) is thought to play a role in the interactions between Streptococcus pyogenes and host cells. We have examined the effect of exogenous LTA on the adherence and entry of S. pyogenes JRS4 strain into HEp-2 epithelial cells. LTA markedly inhibited bacterial entry in a concentration-dependent manner, up to 250 microg ml(-1). In contrast, LTA had only a slight inhibitory effect on adherence. LTA also inhibited the entry but not adherence of Salmonella typhimurium strain into HEp-2 cells. Binding experiments showed a dose-dependent binding of LTA to cells up to 10 microg ml(-1). Confocal laser microscopy imaging and analysis revealed that LTA was internalized by the epithelial cells and colocalized with F-actin. These results might imply that, following binding, exogenous LTA enters HEp-2 cells and exerts a cytotoxic effect that interferes with bacterial internalization. A possible target for LTA activity might be the actin cytoskeleton, which is known to be essential for bacterial uptake.
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Affiliation(s)
- S Sela
- Department of Human Microbiology, Sackler school of Medicine, Tel-Aviv University, Ramat Aviv, Israel.
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6
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Grieshaber S, Petersen NS. The Drosophila forked protein induces the formation of actin fiber bundles in vertebrate cells. J Cell Sci 1999; 112 ( Pt 13):2203-11. [PMID: 10362550 DOI: 10.1242/jcs.112.13.2203] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The forked protein is an actin binding protein involved in the formation of large actin fiber bundles in developing Drosophila bristles. These are the largest example of a type of actin bundle characterized by parallel, hexagonally packed actin fibers, also found in intestinal microvilli, kidney proximal tubule microvilli, and stereocilia in the ear. Understanding how these structures are constructed and how that construction is regulated is an important question in cell and developmental biology. Because the timing of forked gene expression coincides with the formation of the actin fiber bundles, and since the forked protein is localized at the site of initiation of these bundles before they form, it has been proposed that the forked protein is an initiator of actin bundle formation. In this paper we show that the forked protein can induce the formation of bundles and increase actin polymerization in vertebrate cells. We use this system to identify regions of the forked protein which are essential for bundle formation and actin co-localization.
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Affiliation(s)
- S Grieshaber
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
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7
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da Costa SR, Yarber FA, Zhang L, Sonee M, Hamm-Alvarez SF. Microtubules facilitate the stimulated secretion of beta-hexosaminidase in lacrimal acinar cells. J Cell Sci 1998; 111 ( Pt 9):1267-76. [PMID: 9547304 DOI: 10.1242/jcs.111.9.1267] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Stimulation of lacrimal acini with secretagogues such as carbachol initiates movement and fusion of acinar secretory vesicles with the apical plasma membrane, resulting in release of protein into the nascent tear fluid. Using rabbit lacrimal acini reconstituted in vitro from isolated cells, we have investigated the organization of the apical cytoskeleton and its role in stimulated secretion. Confocal microscopy revealed a microtubule array emanating from the apical region of the acini; the apical region was also enriched in microfilaments and (gamma)-tubulin. Cytokeratin-based intermediate filaments were apically concentrated, and also detected at the cell periphery. Neither confocal microscopy nor biochemical analysis revealed any reorganization of lumenal microfilaments or microtubules which might accompany carbachol-stimulated release of secretory proteins. However, major changes in the acinar microtubule array induced by taxol or nocodazole were correlated with inhibition of carbachol-dependent release of the secreted protein, beta-hexosaminidase. Major changes in lumenal microfilaments induced by jasplakinolide or cytochalasin D did not inhibit the carbachol-dependent release of beta-hexosaminidase; rather, release of beta-hexosaminidase from jasplakinolide- or cytochalasin D-treated carbachol-stimulated acini was markedly increased relative to the release from untreated stimulated acini. Our findings demonstrate that microtubules play a major role in stimulated lacrimal secretion, and suggest a contributory role for microfilaments.
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Affiliation(s)
- S R da Costa
- Department of Pharmaceutical Sciences, University of Southern California, School of Pharmacy, Los Angeles, CA 90033, USA
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8
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Salas PJ, Rodriguez ML, Viciana AL, Vega-Salas DE, Hauri HP. The apical submembrane cytoskeleton participates in the organization of the apical pole in epithelial cells. J Biophys Biochem Cytol 1997; 137:359-75. [PMID: 9128248 PMCID: PMC2139782 DOI: 10.1083/jcb.137.2.359] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In a previous publication (Rodriguez, M.L., M. Brignoni, and P.J.I. Salas. 1994. J. Cell Sci. 107: 3145-3151), we described the existence of a terminal web-like structure in nonbrush border cells, which comprises a specifically apical cytokeratin, presumably cytokeratin 19. In the present study we confirmed the apical distribution of cytokeratin 19 and expanded that observation to other epithelial cells in tissue culture and in vivo. In tissue culture, subconfluent cell stocks under continuous treatment with two different 21-mer phosphorothioate oligodeoxy nucleotides that targeted cytokeratin 19 mRNA enabled us to obtain confluent monolayers with a partial (40-70%) and transitory reduction in this protein. The expression of other cytoskeletal proteins was undisturbed. This downregulation of cytokeratin 19 resulted in (a) decrease in the number of microvilli; (b) disorganization of the apical (but not lateral or basal) filamentous actin and abnormal apical microtubules; and (c) depletion or redistribution of apical membrane proteins as determined by differential apical-basolateral biotinylation. In fact, a subset of detergent-insoluble proteins was not expressed on the cell surface in cells with lower levels of cytokeratin 19. Apical proteins purified in the detergent phase of Triton X-114 (typically integral membrane proteins) and those differentially extracted in Triton X-100 at 37 degrees C or in n-octyl-beta-D-glycoside at 4 degrees C (representative of GPI-anchored proteins), appeared partially redistributed to the basolateral domain. A transmembrane apical protein, sucrase isomaltase, was found mispolarized in a subpopulation of the cells treated with antisense oligonucleotides, while the basolateral polarity of Na+-K+ATPase was not affected. Both sucrase isomaltase and alkaline phosphatase (a GPI-anchored protein) appeared partially depolarized in A19 treated CACO-2 monolayers as determined by differential biotinylation, affinity purification, and immunoblot. These results suggest that an apical submembrane cytoskeleton of intermediate filaments is expressed in a number of epithelia, including those without a brush border, although it may not be universal. In addition, these data indicate that this structure is involved in the organization of the apical region of the cytoplasm and the apical membrane.
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Affiliation(s)
- P J Salas
- Department of Cell Biology and Anatomy, University of Miami School of Medicine, Florida 33101, USA
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9
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The cytoskeleton of the intestinal epithelium. CYTOSKELETON IN SPECIALIZED TISSUES AND IN PATHOLOGICAL STATES 1996. [DOI: 10.1016/s1874-6020(96)80015-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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10
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Golenhofen N, Doctor RB, Bacallao R, Mandel LJ. Actin and villin compartmentation during ATP depletion and recovery in renal cultured cells. Kidney Int 1995; 48:1837-45. [PMID: 8587243 DOI: 10.1038/ki.1995.482] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
ATP-depletion in renal cultured cells has been used as a model for studying various cytoskeletal and functional alterations induced by renal ischemia. This communication explores the reversibility of these effects utilizing a novel method [1] that depleted ATP (ATP-D) to 2% of control within 30 minutes and caused complete recovery (REC) of ATP in one hour. Under confocal microscopy, ATP-D (30 min) caused thinning of F-actin from the microvilli, cortical region, and basal stress fibers, with the concurrent appearance of intracellular F-actin patches. These changes were more pronounced after 60 minutes of ATP-D. One hour of REC following 30 minutes of ATP-D produced complete recovery of F-actin in each region of the cell. However, after 60 minutes of ATP-D, a heterogeneous F-actin recovery pattern was observed: almost complete recovery of the apical ring and microvilli, thinned cortical actin with occasional breaks along the basolateral membrane, and a dramatic reduction in basal stress fiber density. The time course of cortical actin and actin ring disruption and recovery coincided with a drop recovery in the transepithelial resistance and the cytoskeletal dissociation and reassociation of the Na,K-ATPase. Additionally, the microvilli retracted into the cells during ATP-D, a process that was reversed during REC. Triton extraction and confocal microscopy demonstrated that villin remained closely associated with microvillar actin during both ATP-D and REC. These distinctive regional differences in the responses of F-actin to ATP depletion and repletion in cultured renal epithelial cells may help to clarify some of the differential tubular responses to ischemia and reperfusion in the kidney.
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Affiliation(s)
- N Golenhofen
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA
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Abstract
A new ear in cell biology is at hand with the development of tools for imaging molecular functions in living cells and tissues. Specific chemical and molecular events can now be measured and manipulated in cells in order to explore the mechanisms of cell functions. In particular, cytoskeletal processes are being dissected temporally and spatially in single cells from lower eukaryotes, plants, and animals using light-based reagents and electronic light microscopy.
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Affiliation(s)
- K A Giuliano
- University of Pittsburgh School of Medicine, PA, USA
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12
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Abstract
Recent studies have greatly expanded our understanding of actin-bundling proteins. A new group of actin-bundling proteins, the fascins, has been recognized. An actin-bundling protein inhibits actin depolymerization even under conditions in which it cannot produce a gel, which suggests that bundling proteins may affect actin filament dynamics. A villin-like protein is present in Dictyostelium, shedding doubt on current ideas on the evolution of villin. Domain mapping continues to be a major thrust of research into most groups of bundling proteins.
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Affiliation(s)
- J J Otto
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392
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