1
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Brzeska H, Bagnoli M, Korn ED, Titus MA. Dictyostelium myosin 1F and myosin 1E inhibit actin waves in a lipid-binding-dependent and motor-independent manner. Cytoskeleton (Hoboken) 2021; 77:295-302. [PMID: 32734648 DOI: 10.1002/cm.21627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 07/21/2020] [Accepted: 07/24/2020] [Indexed: 12/23/2022]
Abstract
Actin waves are F-actin-rich entities traveling on the ventral plasma membrane by the treadmilling mechanism. Actin waves were first discovered and are best characterized in Dictyostelium. Class I myosins are unconventional monomeric myosins that bind lipids through their tails. Dictyostelium has seven class I myosins, six of these have tails (Myo1A-F) while one has a very short tail (Myo1K), and three of them (Myo1D, Myo1E and Myo1F) bind PIP3 with high affinity. Localization of five Dictyostelium Class I myosins synchronizes with localization and propagation of actin waves. Myo1B and Myo1C colocalize with actin in actin waves, whereas Myo1D, E and F localize to the PIP3-rich region surrounded by actin waves. Here, we studied the effect of overexpression of the three PIP3 specific Class I myosins on actin waves. We found that ectopic expression of the short-tail Myo1F inhibits wave formation, short-tail Myo1E has similar but weaker inhibitory effect, but long-tail Myo1D does not affect waves. A study of Myo1F mutants shows that its membrane-binding site is absolutely required for wave inhibition, but the head portion is not. The results suggest that PIP3 specificity and the presence of two membrane-binding sites are required for inhibition of actin waves, and that inhibition may be caused by crosslinking of PIP3 heads groups.
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Affiliation(s)
- Hanna Brzeska
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael Bagnoli
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Edward D Korn
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Margaret A Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, USA
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2
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Sechi S, Frappaolo A, Karimpour-Ghahnavieh A, Fraschini R, Giansanti MG. A novel coordinated function of Myosin II with GOLPH3 controls centralspindlin localization during cytokinesis in Drosophila. J Cell Sci 2020; 133:jcs252965. [PMID: 33037125 DOI: 10.1242/jcs.252965] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/07/2020] [Indexed: 12/15/2022] Open
Abstract
In animal cell cytokinesis, interaction of non-muscle myosin II (NMII) with F-actin provides the dominant force for pinching the mother cell into two daughters. Here we demonstrate that celibe (cbe) is a missense allele of zipper, which encodes the Drosophila Myosin heavy chain. Mutation of cbe impairs binding of Zipper protein to the regulatory light chain Spaghetti squash (Sqh). In dividing spermatocytes from cbe males, Sqh fails to concentrate at the equatorial cortex, resulting in thin actomyosin rings that are unable to constrict. We show that cbe mutation impairs localization of the phosphatidylinositol 4-phosphate [PI(4)P]-binding protein Golgi phosphoprotein 3 (GOLPH3, also known as Sauron) and maintenance of centralspindlin at the cell equator of telophase cells. Our results further demonstrate that GOLPH3 protein associates with Sqh and directly binds the centralspindlin subunit Pavarotti. We propose that during cytokinesis, the reciprocal dependence between Myosin and PI(4)P-GOLPH3 regulates centralspindlin stabilization at the invaginating plasma membrane and contractile ring assembly.
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Affiliation(s)
- Stefano Sechi
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Anna Frappaolo
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Angela Karimpour-Ghahnavieh
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Roberta Fraschini
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano Bicocca, 20126, Milano, Italy
| | - Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Piazzale A. Moro 5, 00185 Roma, Italy
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3
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Brzeska H, Gonzalez J, Korn ED, Titus MA. Basic-hydrophobic sites are localized in conserved positions inside and outside of PH domains and affect localization of Dictyostelium myosin 1s. Mol Biol Cell 2020; 31:101-117. [PMID: 31774725 PMCID: PMC6960411 DOI: 10.1091/mbc.e19-08-0475] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/14/2019] [Accepted: 11/22/2019] [Indexed: 11/21/2022] Open
Abstract
Myosin 1s have critical roles in linking membranes to the actin cytoskeleton via direct binding to acidic lipids. Lipid binding may occur through PIP3/PIP2-specific PH domains or nonspecific ionic interactions involving basic-hydrophobic (BH) sites but the mechanism of myosin 1s distinctive lipid targeting is poorly understood. Now we show that PH domains occur in all Dictyostelium myosin 1s and that the BH sites of Myo1A, B, C, D, and F are in conserved positions near the β3/β4 loops of their PH domains. In spite of these shared lipid-binding sites, we observe significant differences in myosin 1s highly dynamic localizations. All myosin 1s except Myo1A are present in macropinocytic structures but only Myo1B and Myo1C are enriched at the edges of macropinocytic cups and associate with the actin in actin waves. In contrast, Myo1D, E, and F are enclosed by the actin wave. Mutations of BH sites affect localization of all Dictyostelium myosin 1s. Notably, mutation of the BH site located within the PH domains of PIP3-specific Myo1D and Myo1F completely eradicates membrane binding. Thus, BH sites are important determinants of motor targeting and may have a similar role in the localization of other myosin 1s.
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Affiliation(s)
- Hanna Brzeska
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jesus Gonzalez
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Edward D. Korn
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Margaret A. Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
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4
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Gerisch G, Prassler J, Butterfield N, Ecke M. Actin Waves and Dynamic Patterning of the Plasma Membrane. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:397-411. [PMID: 31543704 PMCID: PMC6747932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Plasma membrane and underlying actin network are connected to a functional unit that by non-linear interactions is capable of forming patterns. For instance, in cell motility and chemotaxis, cells polarize to form a protruding front and a retracting tail. Here we address dynamic patterns that are formed on a planar substrate surface and are therefore easily accessible to optical recording. In these patterns two distinct areas of the membrane and actin cortex are interconverted at the site of circular actin waves. The inner territory circumscribed by a wave is distinguished from the external area by a high PIP3 content and high Ras activity. In contrast, the external area is occupied with the PIP3-degrading phosphatase PTEN. In the underlying cortex, these areas differ in the proteins associated with the actin network. Actin waves can be formed at zones of increasing as well as decreasing Ras activity. Both types of waves are headed by myosin IB. When waves collide, they usually extinguish each other, and their decay is accompanied by the accumulation of coronin. No membrane patterns have been observed after efficient depolymerization of actin, suggesting that residual actin filaments are necessary for the pattern generating system to work. Where appropriate, we relate the experimental data obtained with Dictyostelium to human normal and malignant cell behavior, in particular to the role of Ras-GAP as an enhancer of macropinocytosis, to mutations in the tumor suppressor PTEN, to frustrated phagocytosis, and to the role of coronin in immune cells and neurons.
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Affiliation(s)
- Guenther Gerisch
- To whom all correspondence should be addressed: Dr. Günther Gerisch, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; Tel: +49 89 8578-2326, Fax: +49 89 8578-3885,
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5
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The Architecture of Traveling Actin Waves Revealed by Cryo-Electron Tomography. Structure 2019; 27:1211-1223.e5. [PMID: 31230946 DOI: 10.1016/j.str.2019.05.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 04/12/2019] [Accepted: 05/17/2019] [Indexed: 02/06/2023]
Abstract
Actin waves are dynamic supramolecular structures involved in cell migration, cytokinesis, adhesion, and neurogenesis. Although wave-like propagation of actin networks is a widespread phenomenon, the actin architecture underlying wave propagation remained unknown. In situ cryo-electron tomography of Dictyostelium cells unveils the wave architecture and provides evidence for wave progression by de novo actin nucleation. Subtomogram averaging reveals the structure of Arp2/3 complex-mediated branch junctions in their native state, and enables quantitative analysis of the 3D organization of branching within the waves. We find an excess of branches directed toward the substrate-attached membrane, and tent-like structures at sites of branch clustering. Fluorescence imaging shows that Arp2/3 clusters follow accumulation of the elongation factor VASP. We propose that filament growth toward the membrane lifts up the actin network as the wave propagates, until depolymerization of oblique filaments at the back causes the collapse of horizontal filaments into a compact layer.
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6
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Veltman DM, Williams TD, Bloomfield G, Chen BC, Betzig E, Insall RH, Kay RR. A plasma membrane template for macropinocytic cups. eLife 2016; 5:e20085. [PMID: 27960076 PMCID: PMC5154761 DOI: 10.7554/elife.20085] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 11/14/2016] [Indexed: 12/18/2022] Open
Abstract
Macropinocytosis is a fundamental mechanism that allows cells to take up extracellular liquid into large vesicles. It critically depends on the formation of a ring of protrusive actin beneath the plasma membrane, which develops into the macropinocytic cup. We show that macropinocytic cups in Dictyostelium are organised around coincident intense patches of PIP3, active Ras and active Rac. These signalling patches are invariably associated with a ring of active SCAR/WAVE at their periphery, as are all examined structures based on PIP3 patches, including phagocytic cups and basal waves. Patch formation does not depend on the enclosing F-actin ring, and patches become enlarged when the RasGAP NF1 is mutated, showing that Ras plays an instructive role. New macropinocytic cups predominantly form by splitting from existing ones. We propose that cup-shaped plasma membrane structures form from self-organizing patches of active Ras/PIP3, which recruit a ring of actin nucleators to their periphery.
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Affiliation(s)
- Douwe M Veltman
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | | | | | - Bi-Chang Chen
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Eric Betzig
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Robert H Insall
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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7
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Liu X, Shu S, Billington N, Williamson CD, Yu S, Brzeska H, Donaldson JG, Sellers JR, Korn ED. Mammalian Nonmuscle Myosin II Binds to Anionic Phospholipids with Concomitant Dissociation of the Regulatory Light Chain. J Biol Chem 2016; 291:24828-24837. [PMID: 27697842 DOI: 10.1074/jbc.m116.739185] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 09/27/2016] [Indexed: 11/06/2022] Open
Abstract
Mammalian cells express three Class II nonmuscle myosins (NM): NM2A, NM2B, and NM2C. The three NM2s have well established essential roles in cell motility, adhesion, and cytokinesis and less well defined roles in vesicle transport and other processes that would require association of NM2s with cell membranes. Previous evidence for the mechanism of NM2-membrane association includes direct interaction of NM2s with membrane lipids and indirect interaction by association of NM2s with membrane-bound F-actin or peripheral membrane proteins. Direct binding of NM2s to phosphatidylserine-liposomes, but not to phosphatidylcholine-liposomes, has been reported, but the molecular basis of the interaction between NM2s and acidic phospholipids has not been previously investigated. We now show that filamentous, full-length NM2A, NM2B, and NM2C and monomeric, non-filamentous heavy meromyosin bind to liposomes containing one or more acidic phospholipids (phosphatidylserine, phosphatidylinositol 4,5-diphosphate, and phosphatidylinositol 3,4,5-triphosphate) but do not bind to 100% phosphatidylcholine-liposomes. Binding of NM2s to acidic liposomes occurs predominantly through interaction of the liposomes with the regulatory light chain (RLC) binding site in the myosin heavy chain with concomitant dissociation of the RLC. Phosphorylation of myosin-bound RLC by myosin light chain kinase substantially inhibits binding to liposomes of both filamentous NM2 and non-filamentous heavy meromyosin; the addition of excess unbound RLC, but not excess unbound essential light chain, competes with liposome binding. Consistent with the in vitro data, we show that endogenous and expressed NM2A associates with the plasma membrane of HeLa cells and fibrosarcoma cells independently of F-actin.
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Affiliation(s)
- Xiong Liu
- From the Laboratories of Cell Biology and
| | - Shi Shu
- From the Laboratories of Cell Biology and
| | - Neil Billington
- Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-1583
| | | | - Shuhua Yu
- From the Laboratories of Cell Biology and
| | | | | | - James R Sellers
- Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-1583
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8
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Brzeska H, Koech H, Pridham KJ, Korn ED, Titus MA. Selective localization of myosin-I proteins in macropinosomes and actin waves. Cytoskeleton (Hoboken) 2016; 73:68-82. [PMID: 26801966 DOI: 10.1002/cm.21275] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 01/20/2016] [Accepted: 01/20/2016] [Indexed: 01/19/2023]
Abstract
Class I myosins are widely expressed with roles in endocytosis and cell migration in a variety of cell types. Dictyostelium express multiple myosin Is, including three short-tailed (Myo1A, Myo1E, Myo1F) and three long-tailed (Myo1B, Myo1C, Myo1D). Here we report the molecular basis of the specific localizations of short-tailed Myo1A, Myo1E, and Myo1F compared to our previously determined localization of long-tailed Myo1B. Myo1A and Myo1B have common and unique localizations consistent with the various features of their tail region; specifically the BH sites in their tails are required for their association with the plasma membrane and heads are sufficient for relocalization to the front of polarized cells. Myo1A does not localize to actin waves and macropinocytic protrusions, in agreement with the absence of a tail region which is required for these localizations of Myo1B. However, in spite of the overall similarity of their domain structures, the cellular distributions of Myo1E and Myo1F are quite different from Myo1A. Myo1E and Myo1F, but not Myo1A, are associated with macropinocytic cups and actin waves. The localizations of Myo1E and Myo1F in macropinocytic structures and actin waves differ from the localization of Myo1B. Myo1B colocalizes with F-actin in the actin waves and at the tips of mature macropinocytic cups whereas Myo1E and Myo1F are in the interior of actin waves and along the entire surface of macropinocytic cups. Our results point to different mechanisms of targeting of short- and long-tailed myosin Is, and are consistent with these myosins having both shared and divergent cellular functions.
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Affiliation(s)
- Hanna Brzeska
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Hilary Koech
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Kevin J Pridham
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Edward D Korn
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Margaret A Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota
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9
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Gerisch G, Ecke M. Wave Patterns in Cell Membrane and Actin Cortex Uncoupled from Chemotactic Signals. Methods Mol Biol 2016; 1407:79-96. [PMID: 27271895 DOI: 10.1007/978-1-4939-3480-5_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
When cells of Dictyostelium discoideum orientate in a gradient of chemoattractant, they are polarized into a protruding front pointing toward the source of attractant, and into a retracting tail. Under the control of chemotactic signal inputs, Ras is activated and PIP3 is synthesized at the front, while the PIP3-degrading phosphatase PTEN decorates the tail region. As a result of signal transduction, actin filaments assemble at the front into dendritic structures associated with the Arp2/3 complex, in contrast to the tail region where a loose actin meshwork is associated with myosin-II and cortexillin, an antiparallel actin-bundling protein. In axenically growing strains of D. discoideum, wave patterns built by the same components evolve in the absence of any external signal input. Since these autonomously generated patterns are constrained to the plane of the substrate-attached cell surface, they are optimally suited to the optical analysis of state transitions between front-like and tail-like states of the membrane and the actin cortex. Here, we describe imaging techniques using fluorescent proteins to probe for the state of the membrane, the reorganization of the actin network, and the dynamics of wave patterns.
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Affiliation(s)
- Günther Gerisch
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried, D-82152, Germany.
| | - Mary Ecke
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried, D-82152, Germany
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10
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Proteomic profiling of the infective trophozoite stage of Acanthamoeba polyphaga. Acta Trop 2014; 140:166-72. [PMID: 25149354 DOI: 10.1016/j.actatropica.2014.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 07/31/2014] [Accepted: 08/08/2014] [Indexed: 01/12/2023]
Abstract
Acanthamoeba polyphaga is a free-living protozoan pathogen, whose infective trophozoite form is capable of causing a blinding keratitis and fatal granulomatous encephalitis in humans. The damage caused by A. polyphaga trophozoites in human corneal or brain infections is the result of several different pathogenic mechanisms that have not yet been elucidated at the molecular level. We performed a comprehensive analysis of the proteins expressed by A. polyphaga trophozoites, based on complementary 2-DE MS/MS and gel-free LC-MS/MS approaches. Overall, 202 non-redundant proteins were identified. An A. polyphaga proteomic map in the pH range 3-10 was produced, with protein identification for 184 of 370 resolved spots, corresponding to 142 proteins. Additionally, 94 proteins were identified by gel-free LC-MS/MS. Functional classification revealed several proteins with potential importance for pathogen survival and infection of mammalian hosts, including surface proteins and proteins related to defense mechanisms. Our study provided the first comprehensive proteomic survey of the trophozoite infective stage of an Acanthamoeba species, and established foundations for prospective, comparative and functional studies of proteins involved in mechanisms of survival, development, and pathogenicity in A. polyphaga and other pathogenic amoebae.
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11
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Liburd J, Chitayat S, Crawley SW, Munro K, Miller E, Denis CM, Spencer HL, Côté GP, Smith SP. Structure of the small Dictyostelium discoideum myosin light chain MlcB provides insights into MyoB IQ motif recognition. J Biol Chem 2014; 289:17030-42. [PMID: 24790102 DOI: 10.1074/jbc.m113.536532] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Dictyostelium discoideum MyoB is a class I myosin involved in the formation and retraction of membrane projections, cortical tension generation, membrane recycling, and phagosome maturation. The MyoB-specific, single-lobe EF-hand light chain MlcB binds the sole IQ motif of MyoB with submicromolar affinity in the absence and presence of Ca(2+). However, the structural features of this novel myosin light chain and its interaction with its cognate IQ motif remain uncharacterized. Here, we describe the NMR-derived solution structure of apoMlcB, which displays a globular four-helix bundle. Helix 1 adopts a unique orientation when compared with the apo states of the EF-hand calcium-binding proteins calmodulin, S100B, and calbindin D9k. NMR-based chemical shift perturbation mapping identified a hydrophobic MyoB IQ binding surface that involves amino acid residues in helices I and IV and the functional N-terminal Ca(2+) binding loop, a site that appears to be maintained when MlcB adopts the holo state. Complementary mutagenesis and binding studies indicated that residues Ile-701, Phe-705, and Trp-708 of the MyoB IQ motif are critical for recognition of MlcB, which together allowed the generation of a structural model of the apoMlcB-MyoB IQ complex. We conclude that the mode of IQ motif recognition by the novel single-lobe MlcB differs considerably from that of stereotypical bilobal light chains such as calmodulin.
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Affiliation(s)
- Janine Liburd
- From the Department of Biomedical and Molecular Sciences and
| | - Seth Chitayat
- From the Department of Biomedical and Molecular Sciences and
| | - Scott W Crawley
- From the Department of Biomedical and Molecular Sciences and
| | - Kim Munro
- the Protein Function Discovery Group, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Emily Miller
- From the Department of Biomedical and Molecular Sciences and
| | - Chris M Denis
- From the Department of Biomedical and Molecular Sciences and
| | - Holly L Spencer
- From the Department of Biomedical and Molecular Sciences and
| | - Graham P Côté
- From the Department of Biomedical and Molecular Sciences and the Protein Function Discovery Group, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Steven P Smith
- From the Department of Biomedical and Molecular Sciences and the Protein Function Discovery Group, Queen's University, Kingston, Ontario K7L 3N6, Canada
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12
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Brzeska H, Pridham K, Chery G, Titus MA, Korn ED. The association of myosin IB with actin waves in dictyostelium requires both the plasma membrane-binding site and actin-binding region in the myosin tail. PLoS One 2014; 9:e94306. [PMID: 24747353 PMCID: PMC3991602 DOI: 10.1371/journal.pone.0094306] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 03/15/2014] [Indexed: 01/15/2023] Open
Abstract
F-actin structures and their distribution are important determinants of the dynamic shapes and functions of eukaryotic cells. Actin waves are F-actin formations that move along the ventral cell membrane driven by actin polymerization. Dictyostelium myosin IB is associated with actin waves but its role in the wave is unknown. Myosin IB is a monomeric, non-filamentous myosin with a globular head that binds to F-actin and has motor activity, and a non-helical tail comprising a basic region, a glycine-proline-glutamine-rich region and an SH3-domain. The basic region binds to acidic phospholipids in the plasma membrane through a short basic-hydrophobic site and the Gly-Pro-Gln region binds F-actin. In the current work we found that both the basic-hydrophobic site in the basic region and the Gly-Pro-Gln region of the tail are required for the association of myosin IB with actin waves. This is the first evidence that the Gly-Pro-Gln region is required for localization of myosin IB to a specific actin structure in situ. The head is not required for myosin IB association with actin waves but binding of the head to F-actin strengthens the association of myosin IB with waves and stabilizes waves. Neither the SH3-domain nor motor activity is required for association of myosin IB with actin waves. We conclude that myosin IB contributes to anchoring actin waves to the plasma membranes by binding of the basic-hydrophobic site to acidic phospholipids in the plasma membrane and binding of the Gly-Pro-Gln region to F-actin in the wave.
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Affiliation(s)
- Hanna Brzeska
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
| | - Kevin Pridham
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Godefroy Chery
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Margaret A. Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Edward D. Korn
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
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13
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Bi J, Chase SE, Pellenz CD, Kurihara H, Fanning AS, Krendel M. Myosin 1e is a component of the glomerular slit diaphragm complex that regulates actin reorganization during cell-cell contact formation in podocytes. Am J Physiol Renal Physiol 2013; 305:F532-44. [PMID: 23761676 DOI: 10.1152/ajprenal.00223.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glomerular visceral epithelial cells, also known as podocytes, are critical to both normal kidney function and the development of kidney disease. Podocyte actin cytoskeleton and their highly specialized cell-cell junctions (also called slit diaphragm complexes) play key roles in controlling glomerular filtration. Myosin 1e (myo1e) is an actin-based molecular motor that is expressed in renal glomeruli. Disruption of the Myo1e gene in mice and humans promotes podocyte injury and results in the loss of the integrity of the glomerular filtration barrier. Here, we have used biochemical and microscopic approaches to determine whether myo1e is associated with the slit diaphragm complexes in glomerular podocytes. Myo1e was consistently enriched in the slit diaphragm fraction during subcellular fractionation of renal glomeruli and colocalized with the slit diaphragm markers in mouse kidney. Live cell imaging studies showed that myo1e was recruited to the newly formed cell-cell junctions in cultured podocytes, where it colocalized with the actin filament cables aligned with the nascent contacts. Myo1e-null podocytes expressing FSGS-associated myo1e mutant (A159P) did not efficiently assemble actin cables along new cell-cell junctions. We have mapped domains in myo1e that were critical for its localization to cell-cell junctions and determined that the SH3 domain of myo1e tail interacts with ZO-1, a component of the slit diaphragm complex and tight junctions. These findings suggest that myo1e represents a component of the slit diaphragm complex and may contribute to regulating junctional integrity in kidney podocytes.
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Affiliation(s)
- J Bi
- Dept. of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210.
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