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Kollmar M, Welz T, Ravi A, Kaufmann T, Alzahofi N, Hatje K, Alghamdi A, Kim J, Briggs DA, Samol-Wolf A, Pylypenko O, Hume AN, Burkhardt P, Faix J, Kerkhoff E. Actomyosin organelle functions of SPIRE actin nucleators precede animal evolution. Commun Biol 2024; 7:832. [PMID: 38977899 PMCID: PMC11231147 DOI: 10.1038/s42003-024-06458-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 06/14/2024] [Indexed: 07/10/2024] Open
Abstract
An important question in cell biology is how cytoskeletal proteins evolved and drove the development of novel structures and functions. Here we address the origin of SPIRE actin nucleators. Mammalian SPIREs work with RAB GTPases, formin (FMN)-subgroup actin assembly proteins and class-5 myosin (MYO5) motors to transport organelles along actin filaments towards the cell membrane. However, the origin and extent of functional conservation of SPIRE among species is unknown. Our sequence searches show that SPIRE exist throughout holozoans (animals and their closest single-celled relatives), but not other eukaryotes. SPIRE from unicellular holozoans (choanoflagellate), interacts with RAB, FMN and MYO5 proteins, nucleates actin filaments and complements mammalian SPIRE function in organelle transport. Meanwhile SPIRE and MYO5 proteins colocalise to organelles in Salpingoeca rosetta choanoflagellates. Based on these observations we propose that SPIRE originated in unicellular ancestors of animals providing an actin-myosin driven exocytic transport mechanism that may have contributed to the evolution of complex multicellular animals.
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Affiliation(s)
- Martin Kollmar
- Group Systems Biology of Motor Proteins, Department of NMR-based Structural Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.
| | - Tobias Welz
- Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Regensburg, Germany
| | - Aishwarya Ravi
- Michael Sars Centre, University of Bergen, Bergen, Norway
| | - Thomas Kaufmann
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Noura Alzahofi
- School of Life Sciences, University of Nottingham, Nottingham, UK
- Biology Department, College of Science, Taibah University, Medina, Kingdom of Saudi Arabia
| | - Klas Hatje
- Group Systems Biology of Motor Proteins, Department of NMR-based Structural Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
- Roche Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Asmahan Alghamdi
- School of Life Sciences, University of Nottingham, Nottingham, UK
- Department of Biology, College of Sciences, Princess Nourah bint Abdulrahman University, Riyadh, Kingdom of Saudi Arabia
| | - Jiyu Kim
- Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Regensburg, Germany
- Department of Anatomy, University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Deborah A Briggs
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Annette Samol-Wolf
- Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Regensburg, Germany
| | - Olena Pylypenko
- Dynamics of Intra-Cellular Organization, Institute Curie, PSL Research University, CNRS UMR144, Paris, France
| | - Alistair N Hume
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | | | - Jan Faix
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Eugen Kerkhoff
- Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Regensburg, Germany.
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2
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Actin-driven chromosome clustering facilitates fast and complete chromosome capture in mammalian oocytes. Nat Cell Biol 2023; 25:439-452. [PMID: 36732633 PMCID: PMC10014578 DOI: 10.1038/s41556-022-01082-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 12/20/2022] [Indexed: 02/04/2023]
Abstract
Accurate chromosome segregation during meiosis is crucial for reproduction. Human and porcine oocytes transiently cluster their chromosomes before the onset of spindle assembly and subsequent chromosome segregation. The mechanism and function of chromosome clustering are unknown. Here we show that chromosome clustering is required to prevent chromosome losses in the long gap phase between nuclear envelope breakdown and the onset of spindle assembly, and to promote the rapid capture of all chromosomes by the acentrosomal spindle. The initial phase of chromosome clustering is driven by a dynamic network of Formin-2- and Spire-nucleated actin cables. The actin cables form in the disassembling nucleus and migrate towards the nuclear centre, moving the chromosomes centripetally by interacting with their arms and kinetochores as they migrate. A cage of stable microtubule loops drives the late stages of chromosome clustering. Together, our data establish a crucial role for chromosome clustering in accurate progression through meiosis.
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3
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Wang H, Hu J, Yi K, Ma Z, Song X, Lee Y, Kalab P, Bershadsky AD, Miao Y, Li R. Dual control of formin-nucleated actin assembly by the chromatin and ER in mouse oocytes. Curr Biol 2022; 32:4013-4024.e6. [PMID: 35981539 PMCID: PMC9549573 DOI: 10.1016/j.cub.2022.07.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/23/2022] [Accepted: 07/21/2022] [Indexed: 11/29/2022]
Abstract
The first asymmetric meiotic cell divisions in mouse oocytes are driven by formin 2 (FMN2)-nucleated actin polymerization around the spindle. In this study, we investigated how FMN2 is recruited to the spindle peripheral ER and how its activity is regulated in mouse meiosis I (MI) oocytes. We show that this process is regulated by the Ran GTPase, a conserved mediator of chromatin signal, and the ER-associated protein VAPA. FMN2 contains a nuclear localization sequence (NLS) within a domain (SLD) previously shown to be required for FMN2 localization to the spindle periphery. FMN2 NLS is bound to the importin α1/β complex, and the disruption of this interaction by RanGTP is required for FMN2 accumulation in the area proximal to the chromatin and the MI spindle. The importin-free FMN2 is then recruited to the surface of ER around the spindle through the binding of the SLD with the ER-membrane protein VAPA. We further show that FMN2 is autoinhibited through an intramolecular interaction between the SLD with the C-terminal formin homology 2 (FH2) domain that nucleates actin filaments. VAPA binding to SLD relieves the autoinhibition of FMN2, leading to localized actin polymerization. This dual control of formin-mediated actin assembly allows actin polymerization to initiate the movement of the meiotic spindle toward the cortex, an essential step in the maturation of the mammalian female gamete.
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Affiliation(s)
- HaiYang Wang
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore
| | - Jinrong Hu
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore
| | - Kexi Yi
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
| | - Zhiming Ma
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - XinJie Song
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore
| | - Yaelim Lee
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore
| | - Petr Kalab
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Alexander D Bershadsky
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore; Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Rong Li
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore; Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore 117558, Singapore; Center for Cell Dynamics and Department of Cell Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, Baltimore, MD 21205, USA.
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4
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Li J, Peng T, Wang L, Long P, Quan R, Tan H, Zeng M, Wu X, Yang J, Xiao H, Shi X. Heterozygous FMN2 missense variant found in a family case of premature ovarian insufficiency. J Ovarian Res 2022; 15:31. [PMID: 35227295 PMCID: PMC8886936 DOI: 10.1186/s13048-022-00960-y] [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: 08/20/2021] [Accepted: 02/12/2022] [Indexed: 11/29/2022] Open
Abstract
Background Premature ovarian insufficiency (POI) plagues 1% of women under 40, while quite a few remain an unknown cause. The development of sequencing has helped find pathogenic genes and reveal the relationship between DNA repair and ovarian reserve. Through the exome sequencing, our study targets screening out the possible POI pathogenic gene and variants in a Chinese family and 20 sporadic POI patients, preliminarily exploring the functional impact and finding out potential linkages between the gene and POI. Results The whole exome sequencing suggested a novel FMN2 heterozygous variant c.1949C > T (p.Ser650Leu) carried by all three patients in a Chinese family and another c.1967G > A(p.Arg656His) variant in a sporadic case. Since no FMN2 missense mutation is reported for causing human POI, we preliminarily assessed p.Ser650Leu variant via cross-species alignment and 3D modeling and found it possibly deleterious. A series of functional evidence was consistent with our hypothesis. We proved the expression of FMN2 in different stages of oocytes and observed a statistical difference of chromosomal breakages between the POI patient carrying p.Arg656His variant and the health control (p = 0.0013). Western Blot also suggested a decrease in FMN2 and P21 in the mutant type and an associated increase in H2AX. The p.Arg656His variant with an extremely low frequency also indicated that the gene FMN2 might play an essential role in the genetic etiology of POI. To the best of our knowledge, this is the first POI report on missense variants of FMN2. Conclusion This finding indicates a novel gene possibly related to POI and sheds lights on the study of FMN2. Supplementary Information The online version contains supplementary material available at 10.1186/s13048-022-00960-y.
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Affiliation(s)
- Jie Li
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The Second Xiangya Hospital, Central South University, Changsha, 410011, China
| | - Tianliu Peng
- Institute of Reproductive & Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, 410013, China
| | - Le Wang
- Institute of Reproductive & Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, 410013, China
| | - Panpan Long
- Institute of Reproductive & Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, 410013, China
| | - Ruping Quan
- Institute of Reproductive & Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, 410013, China
| | - Hangjing Tan
- Institute of Reproductive & Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, 410013, China
| | - Minghua Zeng
- Institute of Reproductive & Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, 410013, China
| | - Xue Wu
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The Second Xiangya Hospital, Central South University, Changsha, 410011, China
| | - Junting Yang
- Institute of Reproductive & Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, 410013, China
| | - Hongmei Xiao
- Institute of Reproductive & Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, 410013, China.
| | - Xiaobo Shi
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The Second Xiangya Hospital, Central South University, Changsha, 410011, China.
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5
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Torres AA, Macilwee SL, Rashid A, Cox SE, Albarnaz JD, Bonjardim CA, Smith GL. The actin nucleator Spir-1 is a virus restriction factor that promotes innate immune signalling. PLoS Pathog 2022; 18:e1010277. [PMID: 35148361 PMCID: PMC8870497 DOI: 10.1371/journal.ppat.1010277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 02/24/2022] [Accepted: 01/12/2022] [Indexed: 12/12/2022] Open
Abstract
Cellular proteins often have multiple and diverse functions. This is illustrated with protein Spir-1 that is an actin nucleator, but, as shown here, also functions to enhance innate immune signalling downstream of RNA sensing by RIG-I/MDA-5. In human and mouse cells lacking Spir-1, IRF3 and NF-κB-dependent gene activation is impaired, whereas Spir-1 overexpression enhanced IRF3 activation. Furthermore, the infectious virus titres and sizes of plaques formed by two viruses that are sensed by RIG-I, vaccinia virus (VACV) and Zika virus, are increased in Spir-1 KO cells. These observations demonstrate the biological importance of Spir-1 in the response to virus infection. Like cellular proteins, viral proteins also have multiple and diverse functions. Here, we also show that VACV virulence factor K7 binds directly to Spir-1 and that a diphenylalanine motif of Spir-1 is needed for this interaction and for Spir-1-mediated enhancement of IRF3 activation. Thus, Spir-1 is a new virus restriction factor and is targeted directly by an immunomodulatory viral protein that enhances virus virulence and diminishes the host antiviral responses.
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Affiliation(s)
- Alice A. Torres
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | | | - Amir Rashid
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Sarah E. Cox
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Jonas D. Albarnaz
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Claudio A. Bonjardim
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Geoffrey L. Smith
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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6
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Holthenrich A, Terglane J, Naß J, Mietkowska M, Kerkhoff E, Gerke V. Spire1 and Myosin Vc promote Ca 2+-evoked externalization of von Willebrand factor in endothelial cells. Cell Mol Life Sci 2022; 79:96. [PMID: 35084586 PMCID: PMC8794916 DOI: 10.1007/s00018-021-04108-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/14/2021] [Accepted: 12/20/2021] [Indexed: 12/13/2022]
Abstract
Weibel–Palade bodies (WPB) are endothelial cell-specific storage granules that regulate vascular hemostasis by releasing the platelet adhesion receptor von Willebrand factor (VWF) following stimulation. Fusion of WPB with the plasma membrane is accompanied by the formation of actin rings or coats that support the expulsion of large multimeric VWF fibers. However, factor(s) organizing these actin ring structures have remained elusive. We now identify the actin-binding proteins Spire1 and Myosin Vc (MyoVc) as cytosolic factors that associate with WPB and are involved in actin ring formation at WPB-plasma membrane fusion sites. We show that both, Spire1 and MyoVc localize only to mature WPB and that upon Ca2+ evoked exocytosis of WPB, Spire1 and MyoVc together with F-actin concentrate in ring-like structures at the fusion sites. Depletion of Spire1 or MyoVc reduces the number of these actin rings and decreases the amount of VWF externalized to the cell surface after histamine stimulation.
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Affiliation(s)
- Anna Holthenrich
- Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, Von-Esmarch-Str. 56, 48149, Münster, Germany
| | - Julian Terglane
- Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, Von-Esmarch-Str. 56, 48149, Münster, Germany
| | - Johannes Naß
- Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, Von-Esmarch-Str. 56, 48149, Münster, Germany
| | - Magdalena Mietkowska
- Institute of Molecular Cell Biology, Zoological Institute, Technical University of Braunschweig, Braunschweig, Germany
| | - Eugen Kerkhoff
- Department of Neurology, Molecular Cell Biology Laboratory, University Hospital Regensburg, Regensburg, Germany
| | - Volker Gerke
- Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, Von-Esmarch-Str. 56, 48149, Münster, Germany.
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7
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Alzahofi N, Welz T, Robinson CL, Page EL, Briggs DA, Stainthorp AK, Reekes J, Elbe DA, Straub F, Kallemeijn WW, Tate EW, Goff PS, Sviderskaya EV, Cantero M, Montoliu L, Nedelec F, Miles AK, Bailly M, Kerkhoff E, Hume AN. Rab27a co-ordinates actin-dependent transport by controlling organelle-associated motors and track assembly proteins. Nat Commun 2020; 11:3495. [PMID: 32661310 PMCID: PMC7359353 DOI: 10.1038/s41467-020-17212-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 06/04/2020] [Indexed: 11/09/2022] Open
Abstract
Cell biologists generally consider that microtubules and actin play complementary roles in long- and short-distance transport in animal cells. On the contrary, using melanosomes of melanocytes as a model, we recently discovered that the motor protein myosin-Va works with dynamic actin tracks to drive long-range organelle dispersion in opposition to microtubules. This suggests that in animals, as in yeast and plants, myosin/actin can drive long-range transport. Here, we show that the SPIRE-type actin nucleators (predominantly SPIRE1) are Rab27a effectors that co-operate with formin-1 to generate actin tracks required for myosin-Va-dependent transport in melanocytes. Thus, in addition to melanophilin/myosin-Va, Rab27a can recruit SPIREs to melanosomes, thereby integrating motor and track assembly activity at the organelle membrane. Based on this, we suggest a model in which organelles and force generators (motors and track assemblers) are linked, forming an organelle-based, cell-wide network that allows their collective activity to rapidly disperse the population of organelles long-distance throughout the cytoplasm.
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Affiliation(s)
- Noura Alzahofi
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Tobias Welz
- University Hospital Regensburg, Regensburg, Germany
| | | | - Emma L Page
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Deborah A Briggs
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Amy K Stainthorp
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - James Reekes
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - David A Elbe
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Felix Straub
- University Hospital Regensburg, Regensburg, Germany
| | - Wouter W Kallemeijn
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, London, W12 0BZ, UK
| | - Edward W Tate
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, London, W12 0BZ, UK
| | - Philip S Goff
- Cell Biology and Genetics Research Centre, St. George's, University of London, London, SW17 0RE, UK
| | - Elena V Sviderskaya
- Cell Biology and Genetics Research Centre, St. George's, University of London, London, SW17 0RE, UK
| | - Marta Cantero
- Centro Nacional de Biotecnologia (CNB-CSIC), Madrid, 28049, Spain
- CIBERER-ISCIII, Madrid, Spain
| | - Lluis Montoliu
- Centro Nacional de Biotecnologia (CNB-CSIC), Madrid, 28049, Spain
- CIBERER-ISCIII, Madrid, Spain
| | - Francois Nedelec
- Sainsbury Laboratory, Cambridge University, Cambridge, CB2 1LR, UK
| | - Amanda K Miles
- John van Geest Cancer Research Centre, Nottingham Trent University, Nottingham, NG11 8NS, UK
| | - Maryse Bailly
- UCL Institute of Ophthalmology, 11-43 Bath St, London, EC1V 9EL, UK
| | | | - Alistair N Hume
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK.
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8
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Bradley AO, Vizcarra CL, Bailey HM, Quinlan ME. Spire stimulates nucleation by Cappuccino and binds both ends of actin filaments. Mol Biol Cell 2019; 31:273-286. [PMID: 31877067 PMCID: PMC7183766 DOI: 10.1091/mbc.e19-09-0550] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The actin nucleators Spire and Cappuccino synergize to promote actin assembly, but the mechanism of their synergy is controversial. Together these proteins promote the formation of actin meshes, which are conserved structures that regulate the establishment of oocyte polarity. Direct interaction between Spire and Cappuccino is required for oogenesis and for in vitro synergistic actin assembly. This synergy is proposed to be driven by elongation and the formation of a ternary complex at filament barbed ends, or by nucleation and interaction at filament pointed ends. To mimic the geometry of Spire and Cappuccino in vivo, we immobilized Spire on beads and added Cappuccino and actin. Barbed ends, protected by Cappuccino, grow away from the beads while pointed ends are retained, as expected for nucleation-driven synergy. We found that Spire is sufficient to bind barbed ends and retain pointed ends of actin filaments near beads and we identified Spire’s barbed-end binding domain. Loss of barbed-end binding increases nucleation by Spire and synergy with Cappuccino in bulk pyrene assays and on beads. Importantly, genetic rescue by the loss-of-function mutant indicates that barbed-end binding is not necessary for oogenesis. Thus, increased nucleation is a critical element of synergy both in vitro and in vivo.
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Affiliation(s)
- Alexander O Bradley
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Christina L Vizcarra
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Hannah M Bailey
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Margot E Quinlan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095.,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095
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9
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Alqassim SS, Lee IG, Dominguez R. Rickettsia Sca2 Recruits Two Actin Subunits for Nucleation but Lacks WH2 Domains. Biophys J 2019; 116:540-550. [PMID: 30638962 DOI: 10.1016/j.bpj.2018.12.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/07/2018] [Accepted: 12/12/2018] [Indexed: 11/16/2022] Open
Abstract
The Rickettsia ∼1800-amino-acid autotransporter protein surface cell antigen 2 (Sca2) promotes actin polymerization on the surface of the bacterium to drive its movement using an actin comet-tail mechanism. Sca2 mimics eukaryotic formins in that it promotes both actin filament nucleation and elongation and competes with capping protein to generate filaments that are long and unbranched. However, despite these functional similarities, Sca2 is structurally unrelated to eukaryotic formins and achieves these functions through an entirely different mechanism. Thus, while formins are dimeric, Sca2 functions as a monomer. However, Sca2 displays intramolecular interactions and functional cooperativity between its N- and C-terminal domains that are crucial for actin nucleation and elongation. Here, we map the interaction of N- and C- terminal fragments of Sca2 and their contribution to actin binding and nucleation. We find that both the N- and C-terminal regions of Sca2 interact with actin monomers but only weakly, whereas the full-length protein binds two actin monomers with high affinity. Moreover, deletions at both ends of the N- and C-terminal regions disrupt their ability to interact with each other, suggesting that they form a contiguous ring-like structure that wraps around two actin subunits, analogous to the formin homology-2 domain. The discovery of Sca2 as an actin nucleator followed the identification of what appeared to be a repeat of three Wiskott-Aldrich syndrome homology 2 (WH2) domains in the middle of the molecule, consistent with the presence of WH2 domains in most actin nucleators. However, we show here that contrary to previous assumptions, Sca2 does not contain WH2 domains. Instead, our analysis indicates that the region containing the putative WH2 domains is folded as a globular domain that cooperates with other parts of the Sca2 molecule for actin binding and nucleation.
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Affiliation(s)
- Saif S Alqassim
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - In-Gyun Lee
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
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10
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Ginosyan AA, Grintsevich EE, Reisler E. Neuronal drebrin A directly interacts with mDia2 formin to inhibit actin assembly. Mol Biol Cell 2019; 30:646-657. [PMID: 30625038 PMCID: PMC6589693 DOI: 10.1091/mbc.e18-10-0639] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Dendritic spines (DS) are actin-rich postsynaptic terminals of neurons that are critical for higher-order brain functions. Maturation of DS is accompanied by a change in actin architecture from linear to branched filamentous structures. Presumably, the underlying cause of this is a switch in a mode of actin assembly from formin-driven to Arp2/3-mediated via an undefined mechanism. Here we present data suggesting that neuron-specific actin-binding drebrin A may be a part of such a switch. It is well documented that DS are highly enriched in drebrin A, which is critical for their plasticity and function. At the same time, mDia2 is known to mediate the formation of filopodia-type (immature) spines. We found that neuronal drebrin A directly interacts with mDia2 formin. Drebrin inhibits formin-mediated nucleation of actin and abolishes mDia2-induced actin bundling. Using truncated protein constructs we identified the domain requirements for drebrin–mDia2 interaction. We hypothesize that accumulation of drebrin A in DS (that coincides with spine maturation) leads to inhibition of mDia2-driven actin polymerization and, therefore, may contribute to a change in actin architecture from linear to branched filaments.
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Affiliation(s)
- Anush A Ginosyan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Elena E Grintsevich
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095.,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095
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11
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Jo YJ, Lee IW, Jung SM, Kwon J, Kim NH, Namgoong S. Spire localization via zinc finger-containing domain is crucial for the asymmetric division of mouse oocyte. FASEB J 2018; 33:4432-4447. [PMID: 30557038 DOI: 10.1096/fj.201801905r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Zinc plays an essential role in mammalian oocyte maturation, fertilization, and early embryogenesis, and depletion of zinc impairs cell cycle control, asymmetric division, and cytokinesis in oocyte. We report that zinc, via the actin nucleator Spire, acts as an essential regulator of the actin cytoskeleton remodeling during mouse oocyte maturation and fertilization. Depletion of zinc in the mouse oocyte impaired cortical and cytoplasmic actin formation. Spire is colocalized with zinc-containing vesicles via its zinc finger-containing Fab1, YOTB, Vac 1, EEA1 (FYVE) domain. Improper localization of Spire by zinc depletion or mutations in the FYVE domain impair cytoplasmic actin mesh formations and asymmetric division and cytokinesis of oocyte. All 3 major domains of the Spire are required for its proper localization and activity. After fertilization or parthenogenetic activation, Spire localization was dramatically altered following zinc release from the oocyte. Collectively, our data reveal novel roles for zinc in the regulation of the actin nucleator Spire by controlling its localization in mammalian oocyte.-Jo, Y.-J., Lee, I.-W., Jung, S.-M., Kwon, J., Kim, N.-H., Namgoong, S. Spire localization via zinc finger-containing domain is crucial for the asymmetric division of mouse oocyte.
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Affiliation(s)
- Yu-Jin Jo
- Department of Animal Science, Chungbuk National University, Cheongju, North Chungcheong, South Korea
| | - In-Won Lee
- Department of Animal Science, Chungbuk National University, Cheongju, North Chungcheong, South Korea
| | - Seung-Min Jung
- Department of Animal Science, Chungbuk National University, Cheongju, North Chungcheong, South Korea
| | - JeongWoo Kwon
- Department of Animal Science, Chungbuk National University, Cheongju, North Chungcheong, South Korea
| | - Nam-Hyung Kim
- Department of Animal Science, Chungbuk National University, Cheongju, North Chungcheong, South Korea
| | - Suk Namgoong
- Department of Animal Science, Chungbuk National University, Cheongju, North Chungcheong, South Korea
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12
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Almonacid M, Terret ME, Verlhac MH. Control of nucleus positioning in mouse oocytes. Semin Cell Dev Biol 2018; 82:34-40. [DOI: 10.1016/j.semcdb.2017.08.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 08/03/2017] [Indexed: 12/15/2022]
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13
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Hegsted A, Yingling CV, Pruyne D. Inverted formins: A subfamily of atypical formins. Cytoskeleton (Hoboken) 2017; 74:405-419. [PMID: 28921928 DOI: 10.1002/cm.21409] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 08/22/2017] [Accepted: 08/31/2017] [Indexed: 12/25/2022]
Abstract
Formins are a family of regulators of actin and microtubule dynamics that are present in almost all eukaryotes. These proteins are involved in many cellular processes, including cytokinesis, stress fiber formation, and cell polarization. Here we review one subfamily of formins, the inverted formins. Inverted formins as a group break several formin stereotypes, having atypical biochemical properties and domain organization, and they have been linked to kidney disease and neuropathy in humans. In this review, we will explore recent research on members of the inverted formin sub-family in mammals, zebrafish, fruit flies, and worms.
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Affiliation(s)
- Anna Hegsted
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - Curtis V Yingling
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - David Pruyne
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210
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14
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Functional Actin Networks under Construction: The Cooperative Action of Actin Nucleation and Elongation Factors. Trends Biochem Sci 2017; 42:414-430. [DOI: 10.1016/j.tibs.2017.03.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 03/04/2017] [Accepted: 03/07/2017] [Indexed: 12/31/2022]
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15
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Konietzny A, Bär J, Mikhaylova M. Dendritic Actin Cytoskeleton: Structure, Functions, and Regulations. Front Cell Neurosci 2017; 11:147. [PMID: 28572759 PMCID: PMC5435805 DOI: 10.3389/fncel.2017.00147] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 05/05/2017] [Indexed: 12/28/2022] Open
Abstract
Actin is a versatile and ubiquitous cytoskeletal protein that plays a major role in both the establishment and the maintenance of neuronal polarity. For a long time, the most prominent roles that were attributed to actin in neurons were the movement of growth cones, polarized cargo sorting at the axon initial segment, and the dynamic plasticity of dendritic spines, since those compartments contain large accumulations of actin filaments (F-actin) that can be readily visualized using electron- and fluorescence microscopy. With the development of super-resolution microscopy in the past few years, previously unknown structures of the actin cytoskeleton have been uncovered: a periodic lattice consisting of actin and spectrin seems to pervade not only the whole axon, but also dendrites and even the necks of dendritic spines. Apart from that striking feature, patches of F-actin and deep actin filament bundles have been described along the lengths of neurites. So far, research has been focused on the specific roles of actin in the axon, while it is becoming more and more apparent that in the dendrite, actin is not only confined to dendritic spines, but serves many additional and important functions. In this review, we focus on recent developments regarding the role of actin in dendrite morphology, the regulation of actin dynamics by internal and external factors, and the role of F-actin in dendritic protein trafficking.
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Affiliation(s)
- Anja Konietzny
- DFG Emmy Noether Group 'Neuronal Protein Transport,' Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Julia Bär
- DFG Emmy Noether Group 'Neuronal Protein Transport,' Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Marina Mikhaylova
- DFG Emmy Noether Group 'Neuronal Protein Transport,' Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-EppendorfHamburg, Germany
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16
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Welz T, Kerkhoff E. Exploring the iceberg: Prospects of coordinated myosin V and actin assembly functions in transport processes. Small GTPases 2017; 10:111-121. [PMID: 28394692 DOI: 10.1080/21541248.2017.1281863] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Spir actin nucleators and myosin V motor proteins were recently discovered to coexist in a protein complex. The direct interaction allows the coordinated activation of actin motor proteins and actin filament track generation at vesicle membranes. By now the cooperation of myosin V (MyoV) motors and Spir actin nucleation function has only been shown in the exocytic transport of Rab11 vesicles in metaphase mouse oocytes. Next to Rab11, myosin V motors however interact with a variety of Rab GTPases including Rab3, Rab8 and Rab10. As a common theme most of the MyoV interacting Rab GTPases function at different steps along the exocytic transport routes. We here summarize the different transport functions of class V myosins and provide as proof of principle data showing a colocalization of Spir actin nucleators and MyoVa at Rab8a vesicles. This suggests that besides Rab11/MyoV transport also the Rab8/MyoV and possibly other MyoV transport processes recruit Spir actin filament nucleation function.
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Affiliation(s)
- Tobias Welz
- a University Hospital Regensburg, Department of Neurology , Molecular Cell Biology Laboratory , Regensburg , Germany
| | - Eugen Kerkhoff
- a University Hospital Regensburg, Department of Neurology , Molecular Cell Biology Laboratory , Regensburg , Germany
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17
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Pylypenko O, Welz T, Tittel J, Kollmar M, Chardon F, Malherbe G, Weiss S, Michel CIL, Samol-Wolf A, Grasskamp AT, Hume A, Goud B, Baron B, England P, Titus MA, Schwille P, Weidemann T, Houdusse A, Kerkhoff E. Coordinated recruitment of Spir actin nucleators and myosin V motors to Rab11 vesicle membranes. eLife 2016; 5. [PMID: 27623148 PMCID: PMC5021521 DOI: 10.7554/elife.17523] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/18/2016] [Indexed: 12/22/2022] Open
Abstract
There is growing evidence for a coupling of actin assembly and myosin motor activity in cells. However, mechanisms for recruitment of actin nucleators and motors on specific membrane compartments remain unclear. Here we report how Spir actin nucleators and myosin V motors coordinate their specific membrane recruitment. The myosin V globular tail domain (MyoV-GTD) interacts directly with an evolutionarily conserved Spir sequence motif. We determined crystal structures of MyoVa-GTD bound either to the Spir-2 motif or to Rab11 and show that a Spir-2:MyoVa:Rab11 complex can form. The ternary complex architecture explains how Rab11 vesicles support coordinated F-actin nucleation and myosin force generation for vesicle transport and tethering. New insights are also provided into how myosin activation can be coupled with the generation of actin tracks. Since MyoV binds several Rab GTPases, synchronized nucleator and motor targeting could provide a common mechanism to control force generation and motility in different cellular processes.
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Affiliation(s)
- Olena Pylypenko
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
| | - Tobias Welz
- University Hospital Regensburg, Regensburg, Germany
| | - Janine Tittel
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Martin Kollmar
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Florian Chardon
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
| | - Gilles Malherbe
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
| | - Sabine Weiss
- University Hospital Regensburg, Regensburg, Germany
| | | | | | | | - Alistair Hume
- University of Nottingham, Nottingham, United Kingdom
| | - Bruno Goud
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
| | - Bruno Baron
- Institut Pasteur, Biophysics of Macromolecules and their Interactions, Paris, France.,CNRS, UMR 3528, Paris, France
| | - Patrick England
- Institut Pasteur, Biophysics of Macromolecules and their Interactions, Paris, France.,CNRS, UMR 3528, Paris, France
| | - Margaret A Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, United States
| | - Petra Schwille
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | | | - Anne Houdusse
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
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18
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Namgoong S, Kim NH. Roles of actin binding proteins in mammalian oocyte maturation and beyond. Cell Cycle 2016; 15:1830-43. [PMID: 27152960 DOI: 10.1080/15384101.2016.1181239] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Actin nucleation factors, which promote the formation of new actin filaments, have emerged in the last decade as key regulatory factors controlling asymmetric division in mammalian oocytes. Actin nucleators such as formin-2, spire, and the ARP2/3 complex have been found to be important regulators of actin remodeling during oocyte maturation. Another class of actin-binding proteins including cofilin, tropomyosin, myosin motors, capping proteins, tropomodulin, and Ezrin-Radixin-Moesin proteins are thought to control actin cytoskeleton dynamics at various steps of oocyte maturation. In addition, actin dynamics controlling asymmetric-symmetric transitions after fertilization is a new area of investigation. Taken together, defining the mechanisms by which actin-binding proteins regulate actin cytoskeletons is crucial for understanding the basic biology of mammalian gamete formation and pre-implantation development.
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Affiliation(s)
- Suk Namgoong
- a Department of Animal Sciences , Chungbuk National University , Cheong-Ju , ChungChungBuk-do , Republic of Korea
| | - Nam-Hyung Kim
- a Department of Animal Sciences , Chungbuk National University , Cheong-Ju , ChungChungBuk-do , Republic of Korea
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19
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The WH2 Domain and Actin Nucleation: Necessary but Insufficient. Trends Biochem Sci 2016; 41:478-490. [PMID: 27068179 DOI: 10.1016/j.tibs.2016.03.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/18/2016] [Accepted: 03/11/2016] [Indexed: 11/22/2022]
Abstract
Two types of sequences, proline-rich domains (PRDs) and the WASP-homology 2 (WH2) domain, are found in most actin filament nucleation and elongation factors discovered thus far. PRDs serve as a platform for protein-protein interactions, often mediating the binding of profilin-actin. The WH2 domain is an abundant actin monomer-binding motif comprising ∼17 amino acids. It frequently occurs in tandem repeats, and functions in nucleation by recruiting actin subunits to form the polymerization nucleus. It is found in Spire, Cordon Bleu (Cobl), Leiomodin (Lmod), Arp2/3 complex activators (WASP, WHAMM, WAVE, etc.), the bacterial nucleators VopL/VopF and Sca2, and some formins. Yet, it is argued here that the WH2 domain plays only an auxiliary role in nucleation, always synergizing with other domains or proteins for this activity.
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20
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Montaville P, Kühn S, Compper C, Carlier MF. Role of the C-terminal Extension of Formin 2 in Its Activation by Spire Protein and Processive Assembly of Actin Filaments. J Biol Chem 2015; 291:3302-18. [PMID: 26668326 DOI: 10.1074/jbc.m115.681379] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Indexed: 11/06/2022] Open
Abstract
Formin 2 (Fmn2), a member of the FMN family of formins, plays an important role in early development. This formin cooperates with profilin and Spire, a WASP homology domain 2 (WH2) repeat protein, to stimulate assembly of a dynamic cytoplasmic actin meshwork that facilitates translocation of the meiotic spindle in asymmetric division of mouse oocytes. The kinase-like non-catalytic domain (KIND) of Spire directly interacts with the C-terminal extension of the formin homology domain 2 (FH2) domain of Fmn2, called FSI. This direct interaction is required for the synergy between the two proteins in actin assembly. We have recently demonstrated how Spire, which caps barbed ends via its WH2 domains, activates Fmn2. Fmn2 by itself associates very poorly to filament barbed ends but is rapidly recruited to Spire-capped barbed ends via the KIND domain, and it subsequently displaces Spire from the barbed end to elicit rapid processive assembly from profilin·actin. Here, we address the mechanism by which Spire and Fmn2 compete at barbed ends and the role of FSI in orchestrating this competition as well as in the processivity of Fmn2. We have combined microcalorimetric, fluorescence, and hydrodynamic binding assays, as well as bulk solution and single filament measurements of actin assembly, to show that removal of FSI converts Fmn2 into a Capping Protein. This activity is mimicked by association of KIND to Fmn2. In addition, FSI binds actin at filament barbed ends as a weak capper and plays a role in displacing the WH2 domains of Spire from actin, thus allowing the association of actin-binding regions of FH2 to the barbed end.
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Affiliation(s)
- Pierre Montaville
- From the Cytoskeleton Dynamics and Motility, Institut de Biologie Intégrative de la Cellule, CNRS, 91198 Gif-sur-Yvette, France
| | - Sonja Kühn
- From the Cytoskeleton Dynamics and Motility, Institut de Biologie Intégrative de la Cellule, CNRS, 91198 Gif-sur-Yvette, France
| | - Christel Compper
- From the Cytoskeleton Dynamics and Motility, Institut de Biologie Intégrative de la Cellule, CNRS, 91198 Gif-sur-Yvette, France
| | - Marie-France Carlier
- From the Cytoskeleton Dynamics and Motility, Institut de Biologie Intégrative de la Cellule, CNRS, 91198 Gif-sur-Yvette, France
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21
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Manor U, Bartholomew S, Golani G, Christenson E, Kozlov M, Higgs H, Spudich J, Lippincott-Schwartz J. A mitochondria-anchored isoform of the actin-nucleating spire protein regulates mitochondrial division. eLife 2015; 4:e08828. [PMID: 26305500 PMCID: PMC4574297 DOI: 10.7554/elife.08828] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 08/24/2015] [Indexed: 12/18/2022] Open
Abstract
Mitochondrial division, essential for survival in mammals, is enhanced by an inter-organellar process involving ER tubules encircling and constricting mitochondria. The force for constriction is thought to involve actin polymerization by the ER-anchored isoform of the formin protein inverted formin 2 (INF2). Unknown is the mechanism triggering INF2-mediated actin polymerization at ER-mitochondria intersections. We show that a novel isoform of the formin-binding, actin-nucleating protein Spire, Spire1C, localizes to mitochondria and directly links mitochondria to the actin cytoskeleton and the ER. Spire1C binds INF2 and promotes actin assembly on mitochondrial surfaces. Disrupting either Spire1C actin- or formin-binding activities reduces mitochondrial constriction and division. We propose Spire1C cooperates with INF2 to regulate actin assembly at ER-mitochondrial contacts. Simulations support this model's feasibility and demonstrate polymerizing actin filaments can induce mitochondrial constriction. Thus, Spire1C is optimally positioned to serve as a molecular hub that links mitochondria to actin and the ER for regulation of mitochondrial division.
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Affiliation(s)
- Uri Manor
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, United States
| | - Sadie Bartholomew
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
| | - Gonen Golani
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv, Israel
| | - Eric Christenson
- Unit on Structural and Chemical Biology of Membrane Proteins, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, United States
| | - Michael Kozlov
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv, Israel
| | - Henry Higgs
- Department of Biochemistry, Geisel School of Medicine, Hanover, United States
| | - James Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
| | - Jennifer Lippincott-Schwartz
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, United States
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22
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Park E, Graziano BR, Zheng W, Garabedian M, Goode BL, Eck MJ. Structure of a Bud6/Actin Complex Reveals a Novel WH2-like Actin Monomer Recruitment Motif. Structure 2015; 23:1492-1499. [PMID: 26118535 DOI: 10.1016/j.str.2015.05.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 04/22/2015] [Accepted: 05/11/2015] [Indexed: 10/23/2022]
Abstract
In budding yeast, the actin-binding protein Bud6 cooperates with formins Bni1 and Bnr1 to catalyze the assembly of actin filaments. The nucleation-enhancing activity of Bud6 requires both a "core" domain that binds to the formin and a "flank" domain that binds monomeric actin. Here, we describe the structure of the Bud6 flank domain in complex with actin. Two helices in Bud6(flank) interact with actin; one binds in a groove at the barbed end of the actin monomer in a manner closely resembling the helix of WH2 domains, a motif found in many actin nucleation factors. The second helix rises along the face of actin. Mutational analysis verifies the importance of these Bud6-actin contacts for nucleation-enhancing activity. The Bud6 binding site on actin overlaps with that of the formin FH2 domain and is also incompatible with inter-subunit contacts in F-actin, suggesting that Bud6 interacts only transiently with actin monomers during filament nucleation.
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Affiliation(s)
- Eunyoung Park
- Department of Cancer Biology, Dana-Farber Cancer Institute, SM1036, 450 Brookline Avenue, Boston, MA 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Brian R Graziano
- Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA
| | - Wei Zheng
- Department of Cancer Biology, Dana-Farber Cancer Institute, SM1036, 450 Brookline Avenue, Boston, MA 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Mikael Garabedian
- Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA
| | - Bruce L Goode
- Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA
| | - Michael J Eck
- Department of Cancer Biology, Dana-Farber Cancer Institute, SM1036, 450 Brookline Avenue, Boston, MA 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA.
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23
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Tittel J, Welz T, Czogalla A, Dietrich S, Samol-Wolf A, Schulte M, Schwille P, Weidemann T, Kerkhoff E. Membrane targeting of the Spir·formin actin nucleator complex requires a sequential handshake of polar interactions. J Biol Chem 2015; 290:6428-44. [PMID: 25564607 DOI: 10.1074/jbc.m114.602672] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Spir and formin (FMN)-type actin nucleators initiate actin polymerization at vesicular membranes necessary for long range vesicular transport processes. Here we studied in detail the membrane binding properties and protein/protein interactions that govern the assembly of the membrane-associated Spir·FMN complex. Using biomimetic membrane models we show that binding of the C-terminal Spir-2 FYVE-type zinc finger involves both the presence of negatively charged lipids and hydrophobic contributions from the turret loop that intrudes the lipid bilayer. In solution, we uncovered a yet unknown intramolecular interaction between the Spir-2 FYVE-type domain and the N-terminal kinase non-catalytic C-lobe domain (KIND) that could not be detected in the membrane-bound state. Interestingly, we found that the intramolecular Spir-2 FYVE/KIND and the trans-regulatory Fmn-2-FSI/Spir-2-KIND interactions are competitive. We therefore characterized co-expressed Spir-2 and Fmn-2 fluorescent protein fusions in living cells by fluorescence cross-correlation spectroscopy. The data corroborate a model according to which Spir-2 exists in two different states, a cytosolic monomeric conformation and a membrane-bound state in which the KIND domain is released and accessible for subsequent Fmn-2 recruitment. This sequence of interactions mechanistically couples membrane binding of Spir to the recruitment of FMN, a pivotal step for initiating actin nucleation at vesicular membranes.
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Affiliation(s)
- Janine Tittel
- From the Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany, Biotechnology Center (BIOTEC), Biophysics Research Group and
| | - Tobias Welz
- Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, D-93053 Regensburg, Germany, and
| | - Aleksander Czogalla
- Paul Langerhans Institute, Technische Universität (TU) Dresden, Tatzberg 47-51, D-01307 Dresden, Germany, German Center for Diabetes Research (Deutsches Zentrum für Diabetesforschung), 85764 Neuherberg, Germany
| | - Susanne Dietrich
- Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, D-93053 Regensburg, Germany, and
| | - Annette Samol-Wolf
- Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, D-93053 Regensburg, Germany, and
| | - Markos Schulte
- Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, D-93053 Regensburg, Germany, and
| | - Petra Schwille
- From the Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany, Biotechnology Center (BIOTEC), Biophysics Research Group and
| | - Thomas Weidemann
- From the Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany, Biotechnology Center (BIOTEC), Biophysics Research Group and
| | - Eugen Kerkhoff
- Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, D-93053 Regensburg, Germany, and
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24
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Vizcarra CL, Bor B, Quinlan ME. The role of formin tails in actin nucleation, processive elongation, and filament bundling. J Biol Chem 2014; 289:30602-30613. [PMID: 25246531 DOI: 10.1074/jbc.m114.588368] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Formins are multidomain proteins that assemble actin in a wide variety of biological processes. They both nucleate and remain processively associated with growing filaments, in some cases accelerating filament growth. The well conserved formin homology 1 and 2 domains were originally thought to be solely responsible for these activities. Recently a role in nucleation was identified for the Diaphanous autoinhibitory domain (DAD), which is C-terminal to the formin homology 2 domain. The C-terminal tail of the Drosophila formin Cappuccino (Capu) is conserved among FMN formins but distinct from other formins. It does not have a DAD domain. Nevertheless, we find that Capu-tail plays a role in filament nucleation similar to that described for mDia1 and other formins. Building on this, replacement of Capu-tail with DADs from other formins tunes nucleation activity. Capu-tail has low-affinity interactions with both actin monomers and filaments. Removal of the tail reduces actin filament binding and bundling. Furthermore, when the tail is removed, we find that processivity is compromised. Despite decreased processivity, the elongation rate of filaments is unchanged. Again, replacement of Capu-tail with DADs from other formins tunes the processive association with the barbed end, indicating that this is a general role for formin tails. Our data show a role for the Capu-tail domain in assembling the actin cytoskeleton, largely mediated by electrostatic interactions. Because of its multifunctionality, the formin tail is a candidate for regulation by other proteins during cytoskeletal rearrangements.
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Affiliation(s)
- Christina L Vizcarra
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095
| | - Batbileg Bor
- Molecular Biology Interdepartmental Ph.D. Program, and University of California Los Angeles, Los Angeles, California 90095
| | - Margot E Quinlan
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095; Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095.
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25
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Spire and Formin 2 synergize and antagonize in regulating actin assembly in meiosis by a ping-pong mechanism. PLoS Biol 2014; 12:e1001795. [PMID: 24586110 PMCID: PMC3934834 DOI: 10.1371/journal.pbio.1001795] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 01/14/2014] [Indexed: 11/24/2022] Open
Abstract
An in vitro study reveals how the three actin binding proteins profilin, formin 2, and Spire functionally cooperate by a ping-pong mechanism to regulate actin assembly during reproductive cell division. In mammalian oocytes, three actin binding proteins, Formin 2 (Fmn2), Spire, and profilin, synergistically organize a dynamic cytoplasmic actin meshwork that mediates translocation of the spindle toward the cortex and is required for successful fertilization. Here we characterize Fmn2 and elucidate the molecular mechanism for this synergy, using bulk solution and individual filament kinetic measurements of actin assembly dynamics. We show that by capping filament barbed ends, Spire recruits Fmn2 and facilitates its association with barbed ends, followed by rapid processive assembly and release of Spire. In the presence of actin, profilin, Spire, and Fmn2, filaments display alternating phases of rapid processive assembly and arrested growth, driven by a “ping-pong” mechanism, in which Spire and Fmn2 alternately kick off each other from the barbed ends. The results are validated by the effects of injection of Spire, Fmn2, and their interacting moieties in mouse oocytes. This original mechanism of regulation of a Rho-GTPase–independent formin, recruited by Spire at Rab11a-positive vesicles, supports a model for modulation of a dynamic actin-vesicle meshwork in the oocyte at the origin of asymmetric positioning of the meiotic spindle. Mammalian reproduction requires successful meiosis, which consists of two strongly asymmetric cell divisions. In meiosis I, movement of the spindle (the subcellular structure that segregates chromosomes during division) toward the oocyte cortex (the outer layer of the egg) is essential for fertility. This process requires that actin filaments assemble in a dynamic mesh, driven by three actin binding proteins, profilin, formin 2, and Spire. To date the molecular mechanisms by which these three proteins cooperate are not known. We now explore this in vitro by a combination of bulk solution and single actin filament assembly assays in the presence of profilin, Spire, and formin 2. Individually, Spire binds to actin filament ends to block their growth, and by itself, formin 2 associates poorly with filament ends, promoting fast processive assembly from the profilin-actin complex. However, when present together, Spire and formin 2 interact with one another (the formin 2 C-terminal binds to the N terminal Spire KIND domain), forming transient complexes at filament ends from which each binds alternately to the filament ends to regulate actin assembly by a ping-pong mechanism. Our in vitro observations are validated by injection studies in mouse oocytes. In oocytes, the additional interaction of Spire and formin 2 with Rab11a-myosin Vb vesicles couples high actin dynamics to vesicle traffic.
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Pleiser S, Banchaabouchi MA, Samol-Wolf A, Farley D, Welz T, Wellbourne-Wood J, Gehring I, Linkner J, Faix J, Riemenschneider MJ, Dietrich S, Kerkhoff E. Enhanced fear expression in Spir-1 actin organizer mutant mice. Eur J Cell Biol 2013; 93:225-37. [PMID: 24345451 DOI: 10.1016/j.ejcb.2013.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 11/01/2013] [Accepted: 11/05/2013] [Indexed: 12/15/2022] Open
Abstract
Spir proteins nucleate actin filaments at vesicle membranes and facilitate intracellular transport processes. The mammalian genome encodes two Spir proteins, namely Spir-1 and Spir-2. While the mouse spir-2 gene has a rather broad expression pattern, high levels of spir-1 expression are restricted to the nervous system, oocytes, and testis. Spir-1 mutant mice generated by a gene trap method have been employed to address Spir-1 function during mouse development and in adult mouse tissues, with a specific emphasis on viability, reproduction, and the nervous system. The gene trap cassette disrupts Spir-1 expression between the N-terminal KIND domain and the WH2 domain cluster. Spir-1 mutant mice are viable and were born in a Mendelian ratio. In accordance with the redundant function of Spir-1 and Spir-2 in oocyte maturation, spir-1 mutant mice are fertile. The overall brain anatomy of spir-1 mutant mice is not altered and visual and motor functions of the mice remain normal. Microscopic analysis shows a slight reduction in the number of dendritic spines on cortical neurons. Detailed behavioral studies of the spir-1 mutant mice, however, unveiled a very specific and highly significant phenotype in terms of fear learning in male mice. In contextual and cued fear conditioning experiments the male spir-1 mutant mice display increased fear memory when compared to their control littermates. Our data point toward a particular function of the vesicle associated Spir-1 actin organizer in neuronal circuits determining fear behavior.
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Affiliation(s)
- Sandra Pleiser
- University Hospital Regensburg, Department of Neurology, Molecular Cell Biology Laboratory, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
| | - Mumna Al Banchaabouchi
- European Molecular Biology Laboratory (EMBL), Mouse Biology Unit, Via Ramarini 32, 00015 Monterotondo, Italy; Campus Vienna Biocenter, CSF - Campus Science Support Facilities GmbH, Dr. Bohr-Gasse 7, 1020 Vienna, Austria
| | - Annette Samol-Wolf
- University Hospital Regensburg, Department of Neurology, Molecular Cell Biology Laboratory, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
| | - Dominika Farley
- European Molecular Biology Laboratory (EMBL), Mouse Biology Unit, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Tobias Welz
- University Hospital Regensburg, Department of Neurology, Molecular Cell Biology Laboratory, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
| | - Joel Wellbourne-Wood
- University Hospital Regensburg, Department of Neurology, Molecular Cell Biology Laboratory, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
| | - Isabell Gehring
- University Hospital Regensburg, Department of Neurology, Molecular Cell Biology Laboratory, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
| | - Jörn Linkner
- Hannover Medical School, Institute for Biophysical Chemistry, Carl-Neuberg Straße 1, 30625 Hannover, Germany
| | - Jan Faix
- Hannover Medical School, Institute for Biophysical Chemistry, Carl-Neuberg Straße 1, 30625 Hannover, Germany
| | - Markus J Riemenschneider
- Regensburg University Hospital, Department of Neuropathology, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
| | - Susanne Dietrich
- University Hospital Regensburg, Department of Neurology, Molecular Cell Biology Laboratory, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
| | - Eugen Kerkhoff
- University Hospital Regensburg, Department of Neurology, Molecular Cell Biology Laboratory, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany.
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Sun SC, Kim NH. Molecular mechanisms of asymmetric division in oocytes. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2013; 19:883-897. [PMID: 23764118 DOI: 10.1017/s1431927613001566] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In contrast to symmetric division in mitosis, mammalian oocyte maturation is characterized by asymmetric cell division that produces a large egg and a small polar body. The asymmetry results from oocyte polarization, which includes spindle positioning, migration, and cortical reorganization, and this process is critical for fertilization and the retention of maternal components for early embryo development. Although actin dynamics are involved in this process, the molecular mechanism underlying this remained unclear until the use of confocal microscopy and live cell imaging became widespread in recent years. Information obtained through a PubMed database search of all articles published in English between 2000 and 2012 that included the phrases "oocyte, actin, spindle migration," "oocyte, actin, polar body," or "oocyte, actin, asymmetric division" was reviewed. The actin nucleation factor actin-related protein 2/3 complex and its nucleation-promoting factors, formins and Spire, and regulators such as small GTPases, partitioning-defective/protein kinase C, Fyn, microRNAs, cis-Golgi apparatus components, myosin/myosin light-chain kinase, spindle stability regulators, and spindle assembly checkpoint regulators, play critical roles in asymmetric cell division in oocytes. This review summarizes recent findings on these actin-related regulators in mammalian oocyte asymmetric division and outlines a complete signaling pathway.
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Affiliation(s)
- Shao-Chen Sun
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
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Graziano BR, Jonasson EM, Pullen JG, Gould CJ, Goode BL. Ligand-induced activation of a formin-NPF pair leads to collaborative actin nucleation. ACTA ACUST UNITED AC 2013; 201:595-611. [PMID: 23671312 PMCID: PMC3653363 DOI: 10.1083/jcb.201212059] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Formins associate with other nucleators and nucleation-promoting factors (NPFs) to stimulate collaborative actin assembly, but the mechanisms regulating these interactions have been unclear. Yeast Bud6 has an established role as an NPF for the formin Bni1, but whether it also directly regulates the formin Bnr1 has remained enigmatic. In this paper, we analyzed NPF-impaired alleles of bud6 in a bni1Δ background and found that Bud6 stimulated Bnr1 activity in vivo. Furthermore, Bud6 bound directly to Bnr1, but its NPF effects were masked by a short regulatory sequence, suggesting that additional factors may be required for activation. We isolated a novel in vivo binding partner of Bud6, Yor304c-a/Bil1, which colocalized with Bud6 and functioned in the Bnr1 pathway for actin assembly. Purified Bil1 bound to the regulatory sequence in Bud6 and triggered NPF effects on Bnr1. These observations define a new mode of formin regulation, which has important implications for understanding NPF-nucleator pairs in diverse systems.
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Affiliation(s)
- Brian R Graziano
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
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Jaiswal R, Stepanik V, Rankova A, Molinar O, Goode BL, McCartney BM. Drosophila homologues of adenomatous polyposis coli (APC) and the formin diaphanous collaborate by a conserved mechanism to stimulate actin filament assembly. J Biol Chem 2013; 288:13897-905. [PMID: 23558679 DOI: 10.1074/jbc.m113.462051] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Vertebrate APC collaborates with Dia through its Basic domain to assemble actin filaments. RESULTS Despite limited sequence homology between the vertebrate and Drosophila APC Basic domains, Drosophila APC1 collaborates with Dia to stimulate actin assembly in vitro. CONCLUSION The mechanism of actin assembly is highly conserved over evolution. SIGNIFICANCE APC-Dia collaborations may be crucial in a wide range of animal cells. Adenomatous polyposis coli (APC) is a large multidomain protein that regulates the cytoskeleton. Recently, it was shown that vertebrate APC through its Basic domain directly collaborates with the formin mDia1 to stimulate actin filament assembly in the presence of nucleation barriers. However, it has been unclear whether these activities extend to homologues of APC and Dia in other organisms. Drosophila APC and Dia are each required to promote actin furrow formation in the syncytial embryo, suggesting a potential collaboration in actin assembly, but low sequence homology between the Basic domains of Drosophila and vertebrate APC has left their functional and mechanistic parallels uncertain. To address this question, we purified Drosophila APC1 and Dia and determined their individual and combined effects on actin assembly using both bulk fluorescence assays and total internal reflection fluorescence microscopy. Our data show that APC1, similar to its vertebrate homologue, bound to actin monomers and nucleated and bundled filaments. Further, Drosophila Dia nucleated actin assembly and protected growing filament barbed ends from capping protein. Drosophila APC1 and Dia directly interacted and collaborated to promote actin assembly in the combined presence of profilin and capping protein. Thus, despite limited sequence homology, Drosophila and vertebrate APCs exhibit highly related activities and mechanisms and directly collaborate with formins. These results suggest that APC-Dia interactions in actin assembly are conserved and may underlie important in vivo functions in a broad range of animal phyla.
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Affiliation(s)
- Richa Jaiswal
- Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA
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Bor B, Vizcarra CL, Phillips ML, Quinlan ME. Autoinhibition of the formin Cappuccino in the absence of canonical autoinhibitory domains. Mol Biol Cell 2012; 23:3801-13. [PMID: 22875983 PMCID: PMC3459857 DOI: 10.1091/mbc.e12-04-0288] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Fmn-family formin Cappuccino does not contain classical autoihibitory domains but is autoinhibited. The N-terminus inhibits actin nucleation and competes with elongation. Formins are a conserved family of proteins known to enhance actin polymerization. Most formins are regulated by an intramolecular interaction. The Drosophila formin, Cappuccino (Capu), was believed to be an exception. Capu does not contain conserved autoinhibitory domains and can be regulated by a second protein, Spire. We report here that Capu is, in fact, autoinhibited. The N-terminal half of Capu (Capu-NT) potently inhibits nucleation and binding to the barbed end of elongating filaments by the C-terminal half of Capu (Capu-CT). Hydrodynamic analysis indicates that Capu-NT is a dimer, similar to the N-termini of other formins. These data, combined with those from circular dichroism, suggest, however, that it is structurally distinct from previously described formin inhibitory domains. Finally, we find that Capu-NT binds to a site within Capu-CT that overlaps with the Spire-binding site, the Capu-tail. We propose models for the interaction between Spire and Capu in light of the fact that Capu can be regulated by autoinhibition.
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Affiliation(s)
- Batbileg Bor
- Molecular Biology Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA 90095-1570, USA
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31
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Schevzov G, Curthoys NM, Gunning PW, Fath T. Functional diversity of actin cytoskeleton in neurons and its regulation by tropomyosin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 298:33-94. [PMID: 22878104 DOI: 10.1016/b978-0-12-394309-5.00002-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neurons comprise functionally, molecularly, and spatially distinct subcellular compartments which include the soma, dendrites, axon, branches, dendritic spines, and growth cones. In this chapter, we detail the remarkable ability of the neuronal cytoskeleton to exquisitely regulate all these cytoplasmic distinct partitions, with particular emphasis on the microfilament system and its plethora of associated proteins. Importance will be given to the family of actin-associated proteins, tropomyosin, in defining distinct actin filament populations. The ability of tropomyosin isoforms to regulate the access of actin-binding proteins to the filaments is believed to define the structural diversity and dynamics of actin filaments and ultimately be responsible for the functional outcome of these filaments.
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Affiliation(s)
- Galina Schevzov
- Oncology Research Unit, Department of Pharmacology, School of Medical Sciences, University of New South Wales, Kensington, Australia
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Stastna J, Pan X, Wang H, Kollmannsperger A, Kutscheidt S, Lohmann V, Grosse R, Fackler OT. Differing and isoform-specific roles for the formin DIAPH3 in plasma membrane blebbing and filopodia formation. Cell Res 2011; 22:728-45. [PMID: 22184005 DOI: 10.1038/cr.2011.202] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Plasma membrane (PM) blebs are dynamic actin-rich cell protrusions that occur, e.g., during cytokinesis, amoeboid cell motility and cell attachment. Using a targeted siRNA screen against 21 actin nucleation factors, we identify a novel and essential role of the human diaphanous formin DIAPH3 in PM blebbing during cell adhesion. Suppression of DIAPH3 inhibited blebbing to promote rapid cell spreading involving β1-integrin. Multiple isoforms of DIAPH3 were detected on the mRNA and protein level of which isoforms 3 and 7 were the largest and most abundant isoforms that however did not induce formation of actin-rich protrusions. Rather, PM blebbing specifically involved the low abundance isoform 1 of DIAPH3 and activation of isoform 7 by deletion of the diaphanous-autoregulatory domain caused the formation of filopodia. Dimerization and actin assembly activity were essential for induction of specific cell protrusions by DIAPH3 isoforms 1 and 7. Our data suggest that the N-terminal region comprising the GTPase-binding domain determined the subcellular localization of the formin as well as its protrusion activity between blebs and filopodia. We propose that isoform-selective actin assembly by DIAPH3 exerts specific and differentially regulated functions during cell adhesion and motility.
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Affiliation(s)
- Jana Stastna
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
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Graziano BR, DuPage AG, Michelot A, Breitsprecher D, Moseley JB, Sagot I, Blanchoin L, Goode BL. Mechanism and cellular function of Bud6 as an actin nucleation-promoting factor. Mol Biol Cell 2011; 22:4016-28. [PMID: 21880892 PMCID: PMC3204064 DOI: 10.1091/mbc.e11-05-0404] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Bud6 functions as an actin nucleation–promoting factor (NPF) for Bni1; thus formins can depend on NPFs like the Arp2/3 complex. Unexpected parallels exist between Bud6 and WASp. Bud6 is the first nonmetazoan example of formins pairing with actin monomer–binding proteins to stimulate nucleation, akin to Spire-Capu and APC-mDia1 Formins are a conserved family of actin assembly–promoting factors with diverse biological roles, but how their activities are regulated in vivo is not well understood. In Saccharomyces cerevisiae, the formins Bni1 and Bnr1 are required for the assembly of actin cables and polarized cell growth. Proper cable assembly further requires Bud6. Previously it was shown that Bud6 enhances Bni1-mediated actin assembly in vitro, but the biochemical mechanism and in vivo role of this activity were left unclear. Here we demonstrate that Bud6 specifically stimulates the nucleation rather than the elongation phase of Bni1-mediated actin assembly, defining Bud6 as a nucleation-promoting factor (NPF) and distinguishing its effects from those of profilin. We generated alleles of Bud6 that uncouple its interactions with Bni1 and G-actin and found that both interactions are critical for NPF activity. Our data indicate that Bud6 promotes filament nucleation by recruiting actin monomers to Bni1. Genetic analysis of the same alleles showed that Bud6 regulation of formin activity is critical for normal levels of actin cable assembly in vivo. Our results raise important mechanistic parallels between Bud6 and WASP, as well as between Bud6 and other NPFs that interact with formins such as Spire.
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Affiliation(s)
- Brian R Graziano
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA
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Namgoong S, Boczkowska M, Glista MJ, Winkelman JD, Rebowski G, Kovar DR, Dominguez R. Mechanism of actin filament nucleation by Vibrio VopL and implications for tandem W domain nucleation. Nat Struct Mol Biol 2011; 18:1060-7. [PMID: 21873985 PMCID: PMC3173040 DOI: 10.1038/nsmb.2109] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 06/30/2011] [Indexed: 11/09/2022]
Abstract
Pathogen proteins targeting the actin cytoskeleton often serve as model systems to understand their more complex eukaryotic analogs. We show that the strong actin filament nucleation activity of Vibrio parahaemolyticus VopL depends on its three W domains and on its dimerization through a unique VopL C-terminal domain (VCD). The VCD shows a previously unknown all-helical fold and interacts with the pointed end of the actin nucleus, contributing to the nucleation activity directly and through duplication of the W domain repeat. VopL promotes rapid cycles of filament nucleation and detachment but generally has no effect on elongation. Profilin inhibits VopL-induced nucleation by competing for actin binding to the W domains. Combined, the results suggest that VopL stabilizes a hexameric double-stranded pointed end nucleus. Analysis of hybrid constructs of VopL and the eukaryotic nucleator Spire suggest that Spire may also function as a dimer in cells.
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Affiliation(s)
- Suk Namgoong
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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36
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Structure and function of the interacting domains of Spire and Fmn-family formins. Proc Natl Acad Sci U S A 2011; 108:11884-9. [PMID: 21730168 DOI: 10.1073/pnas.1105703108] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Evidence for cooperation between actin nucleators is growing. The WH2-containing nucleator Spire and the formin Cappuccino interact directly, and both are essential for assembly of an actin mesh during Drosophila oogenesis. Their interaction requires the kinase noncatalytic C-lobe domain (KIND) domain of Spire and the C-terminal tail of the formin. Here we describe the crystal structure of the KIND domain of human Spir1 alone and in complex with the tail of Fmn2, a mammalian ortholog of Cappuccino. The KIND domain is structurally similar to the C-lobe of protein kinases. The Fmn2 tail is coordinated in an acidic cleft at the base of the domain that appears to have evolved via deletion of a helix from the canonical kinase fold. Our functional analysis of Cappuccino reveals an unexpected requirement for its tail in actin assembly. In addition, we find that the KIND/tail interaction blocks nucleation by Cappuccino and promotes its displacement from filament barbed ends providing insight into possible modes of cooperation between Spire and Cappuccino.
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Zeth K, Pechlivanis M, Samol A, Pleiser S, Vonrhein C, Kerkhoff E. Molecular basis of actin nucleation factor cooperativity: crystal structure of the Spir-1 kinase non-catalytic C-lobe domain (KIND)•formin-2 formin SPIR interaction motif (FSI) complex. J Biol Chem 2011; 286:30732-30739. [PMID: 21705804 DOI: 10.1074/jbc.m111.257782] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The distinct actin nucleation factors of the Spir and formin subgroup families cooperate in actin nucleation. The Spir/formin cooperativity has been identified to direct two essential steps in mammalian oocyte maturation, the asymmetric spindle positioning and polar body extrusion during meiosis. Understanding the nature and regulation of the Spir/Fmn cooperation is an important requirement to comprehend mammalian reproduction. Recently we dissected the structural elements of the Spir and Fmn family proteins, which physically link the two actin nucleation factors. The trans-regulatory interaction is mediated by the Spir kinase non-catalytic C-lobe domain (KIND) and the C-terminal formin Spir interaction motif (FSI). The interaction inhibits formin nucleation activity and enhances the Spir activity. To get insights into the molecular mechanism of the Spir/Fmn interaction, we determined the crystal structure of the KIND domain alone and in complex with the C-terminal Fmn-2 FSI peptide. Together they confirm the proposed structural homology of the KIND domain to the protein kinase fold and reveal the basis of the Spir/formin interaction. The complex structure showed a large interface with conserved and positively charged residues of the Fmn FSI peptide mediating major contacts to an acidic groove on the surface of KIND. Protein interaction studies verified the electrostatic nature of the interaction. The data presented here provide the molecular basis of the Spir/formin interaction and give a first structural view into the mechanisms of actin nucleation factor cooperativity.
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Affiliation(s)
- Kornelius Zeth
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Markos Pechlivanis
- Department of Neurology, Molecular Cell Biology Laboratory, Bavarian Genome Research Network (BayGene), University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Annette Samol
- Department of Neurology, Molecular Cell Biology Laboratory, Bavarian Genome Research Network (BayGene), University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Sandra Pleiser
- Department of Neurology, Molecular Cell Biology Laboratory, Bavarian Genome Research Network (BayGene), University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Clemens Vonrhein
- Global Phasing Limited, Sheraton House, Castle Park, Cambridge CB3 0AX, United Kingdom
| | - Eugen Kerkhoff
- Department of Neurology, Molecular Cell Biology Laboratory, Bavarian Genome Research Network (BayGene), University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany.
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Pfender S, Kuznetsov V, Pleiser S, Kerkhoff E, Schuh M. Spire-type actin nucleators cooperate with Formin-2 to drive asymmetric oocyte division. Curr Biol 2011; 21:955-60. [PMID: 21620703 PMCID: PMC3128265 DOI: 10.1016/j.cub.2011.04.029] [Citation(s) in RCA: 189] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 03/30/2011] [Accepted: 04/18/2011] [Indexed: 12/24/2022]
Abstract
Oocytes mature into eggs by extruding half of their chromosomes in a small cell termed the polar body. Asymmetric oocyte division is essential for fertility [1], but despite its importance, little is known about its mechanism. In mammals, the meiotic spindle initially forms close to the center of the oocyte. Thus, two steps are required for asymmetric meiotic division: first, asymmetric spindle positioning and second, polar body extrusion. Here, we identify Spire1 and Spire2 as new key factors in asymmetric division of mouse oocytes. Spire proteins are novel types of actin nucleators that drive nucleation of actin filaments with their four WH2 actin-binding domains [2–6]. We show that Spire1 and Spire2 first mediate asymmetric spindle positioning by assembling an actin network that serves as a substrate for spindle movement. Second, they drive polar body extrusion by promoting assembly of the cleavage furrow. Our data suggest that Spire1 and Spire2 cooperate with Formin-2 (Fmn2) to nucleate actin filaments in mouse oocytes and that both types of nucleators act as a functional unit. This study not only reveals how Spire1 and Spire2 drive two critical steps of asymmetric oocyte division, but it also uncovers the first physiological function of Spire-type actin nucleators in vertebrates.
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Affiliation(s)
- Sybille Pfender
- Medical Research Council, Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
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39
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Human spire interacts with the barbed end of the actin filament. J Mol Biol 2011; 408:18-25. [PMID: 21315084 DOI: 10.1016/j.jmb.2010.12.045] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 12/15/2010] [Accepted: 12/23/2010] [Indexed: 12/24/2022]
Abstract
Spire is an actin nucleator that initiates actin polymerization at a specific place in the cell. Similar to the Arp2/3 complex, spire was initially considered to bind to the pointed end of the actin filament when it generates a new actin filament. Subsequently, spire was reported to be associated with the barbed end (B-end); thus, there is still no consensus regarding the end with which spire interacts. Here, we report direct evidence that spire binds to the B-end of the actin filament, under conditions where spire accelerates actin polymerization. Using electron microscopy, we visualized the location of spire bound to the filament by gold nanoparticle labeling of the histidine-tagged spire, and the polarity of the actin filament was determined by image analysis. In addition, our results suggest that multiple spires, linked through one gold nanoparticle, enhance the acceleration of actin polymerization. The B-end binding of spire provides the basis for understanding its functional mechanism in the cell.
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Carlier MF, Husson C, Renault L, Didry D. Control of Actin Assembly by the WH2 Domains and Their Multifunctional Tandem Repeats in Spire and Cordon-Bleu. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 290:55-85. [DOI: 10.1016/b978-0-12-386037-8.00005-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Kerkhoff E. Actin dynamics at intracellular membranes: the Spir/formin nucleator complex. Eur J Cell Biol 2010; 90:922-5. [PMID: 21129813 DOI: 10.1016/j.ejcb.2010.10.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 10/20/2010] [Accepted: 10/20/2010] [Indexed: 01/09/2023] Open
Abstract
The assembly of actin monomers into filaments is a highly regulated basic cellular function. The structural organization of a cell, morphological changes or cell motility is dependent on actin filament dynamics. While within the last decade substantial knowledge has been acquired about actin dynamics at the cell membrane, today only little is known about the actin cytoskeleton and its functions at intracellular endosomal and organelle membranes. The Spir actin nucleators are specifically targeted towards endosomal membranes by a FYVE zinc finger membrane localization domain, and provide an important link to study the role of actin dynamics in the regulation of intracellular membrane transport. Spir proteins are the founding members of a novel class of actin nucleation factors, which initiate actin polymerization by binding of actin monomers to one or multiple Wiskott-Aldrich syndrome protein (WASp) homology 2 (WH2) domains. Although Spir proteins can nucleate actin polymerization in vitro by themselves, they form a regulatory complex with the distinct actin nucleators of the formin subgroup (Fmn) of formins. A cooperative mechanism in actin nucleation has been proposed. Ongoing studies on the function and regulation of the Spir proteins in vesicle transport processes will reveal important insights into actin dynamics at intracellular membranes and how this regulates the highly directed and controlled routes of intracellular membrane trafficking.
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Affiliation(s)
- Eugen Kerkhoff
- Bavarian Genome Research Network (BayGene), Molecular Cell Biology Laboratory, Department of Neurology, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, D-93053 Regensburg, Germany.
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Gorelik R, Yang C, Kameswaran V, Dominguez R, Svitkina T. Mechanisms of plasma membrane targeting of formin mDia2 through its amino terminal domains. Mol Biol Cell 2010; 22:189-201. [PMID: 21119010 PMCID: PMC3020915 DOI: 10.1091/mbc.e10-03-0256] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
We investigated the poorly understood mechanism of plasma membrane targeting of formin mDia2 and found that its N terminus plays important roles in this process by binding acidic phospholipids through its N-terminal basic domain and by binding small GTPase Rif through direct interaction with the GTPase binding region and the diaphanous inhibitory domain. The formin mDia2 mediates the formation of lamellipodia and filopodia during cell locomotion. The subcellular localization of activated mDia2 depends on interactions with actin filaments and the plasma membrane. We investigated the poorly understood mechanism of plasma membrane targeting of mDia2 and found that the entire N-terminal region of mDia2 preceding the actin-polymerizing formin homology domains 1 and 2 (FH1–FH2) module was potently targeted to the membrane. This localization was enhanced by Rif, but not by other tested small GTPases, and depended on a positively charged N-terminal basic domain (BD). The BD bound acidic phospholipids in vitro, suggesting that in vivo it may associate with the plasma membrane through electrostatic interactions. Unexpectedly, a fragment consisting of the GTPase-binding region and the diaphanous inhibitory domain (G-DID), thought to mediate the interaction with GTPases, was not targeted to the plasma membrane even in the presence of constitutively active Rif. Addition of the BD or dimerization/coiled coil domains to G-DID rescued plasma membrane targeting in cells. Direct binding of Rif to mDia2 N terminus required the presence of both G and DID. These results suggest that the entire N terminus of mDia2 serves as a coincidence detection module, directing mDia2 to the plasma membrane through interactions with phospholipids and activated Rif.
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Affiliation(s)
- Roman Gorelik
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Kessels MM, Schwintzer L, Schlobinski D, Qualmann B. Controlling actin cytoskeletal organization and dynamics during neuronal morphogenesis. Eur J Cell Biol 2010; 90:926-33. [PMID: 20965607 DOI: 10.1016/j.ejcb.2010.08.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 08/27/2010] [Accepted: 08/27/2010] [Indexed: 11/26/2022] Open
Abstract
Coordinated functions of the actin cytoskeleton and microtubules, which need to be carefully controlled in time and space, are required for the drastic alterations of neuronal morphology during neuromorphogenesis and neuronal network formation. A key process in neuronal actin dynamics is filament formation by actin nucleators, such as the Arp2/3 complex, formins and the brain-enriched, novel WH2 domain-based nucleators Spire and cordon-bleu (Cobl). We here discuss in detail the currently available data on the roles of these actin nucleators during neuromorphogenesis and highlight how their required control at the plasma membrane may be brought about. The Arp2/3 complex was found to be especially important for proper growth cone translocation and axon development. The underlying molecular mechanisms for Arp2/3 complex activation at the neuronal plasma membrane include a recruitment and an activation of N-WASP by lipid- and F-actin-binding adaptor proteins, Cdc42 and phosphatidyl-inositol-(4,5)-bisphosphate (PIP(2)). Together, these components upstream of N-WASP and the Arp2/3 complex ensure fine-control of N-WASP-mediated Arp2/3 complex activation and control distinct functions during axon development. They are counteracted by Arp2/3 complex inhibitors, such as PICK, which likewise play an important role in neuromorphogenesis. In contrast to the crucial role of the Arp2/3 complex in proper axon development, dendrite formation and dendritic arborization was revealed to critically involve the newly identified actin nucleator Cobl. Cobl is a brain-enriched protein and uses three Wiskott-Aldrich syndrome protein homology 2 (WH2) domains for actin binding and for promoting the formation of non-bundled, unbranched filaments. Thus, cells use different actin nucleators to steer the complex remodeling processes underlying cell morphogenesis, the formation of cellular networks and the development of complex body plans.
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Affiliation(s)
- Michael Manfred Kessels
- Institute for Biochemistry I, University Hospital Jena - Friedrich-Schiller-University Jena, Nonnenplan 2, 07743 Jena, Germany.
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Pleiser S, Rock R, Wellmann J, Gessler M, Kerkhoff E. Expression patterns of the mouse Spir-2 actin nucleator. Gene Expr Patterns 2010; 10:345-50. [DOI: 10.1016/j.gep.2010.08.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 07/30/2010] [Accepted: 08/09/2010] [Indexed: 12/22/2022]
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Structures of actin-bound Wiskott-Aldrich syndrome protein homology 2 (WH2) domains of Spire and the implication for filament nucleation. Proc Natl Acad Sci U S A 2010; 107:11757-62. [PMID: 20538977 DOI: 10.1073/pnas.1005347107] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Three classes of proteins are known to nucleate new filaments: the Arp2/3 complex, formins, and the third group of proteins that contain ca. 25 amino acid long actin-binding Wiskott-Aldrich syndrome protein homology 2 domains, called the WH2 repeats. Crystal structures of the complexes between the actin-binding WH2 repeats of the Spire protein and actin were determined for the Spire single WH2 domain D, the double (SpirCD), triple (SpirBCD), quadruple (SpirABCD) domains, and an artificial Spire WH2 construct comprising three identical D repeats (SpirDDD). SpirCD represents the minimal functional core of Spire that can nucleate actin filaments. Packing in the crystals of the actin complexes with SpirCD, SpirBCD, SpirABCD, and SpirDDD shows the presence of two types of assemblies, "side-to-side" and "straight-longitudinal," which can serve as actin filament nuclei. The principal feature of these structures is their loose, open conformations, in which the sides of actins that normally constitute the inner interface core of a filament are flipped inside out. These Spire structures are distant from those seen in the filamentous nuclei of Arp2/3, formins, and in the F-actin filament.
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Abstract
For over a decade, the actin-related protein 2/3 (ARP2/3) complex, a handful of nucleation-promoting factors and formins were the only molecules known to directly nucleate actin filament formation de novo. However, the past several years have seen a surge in the discovery of mammalian proteins with roles in actin nucleation and dynamics. Newly recognized nucleation-promoting factors, such as WASP and SCAR homologue (WASH), WASP homologue associated with actin, membranes and microtubules (WHAMM), and junction-mediating regulatory protein (JMY), stimulate ARP2/3 activity at distinct cellular locations. Formin nucleators with additional biochemical and cellular activities have also been uncovered. Finally, the Spire, cordon-bleu and leiomodin nucleators have revealed new ways of overcoming the kinetic barriers to actin polymerization.
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Schönichen A, Geyer M. Fifteen formins for an actin filament: a molecular view on the regulation of human formins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:152-63. [PMID: 20102729 DOI: 10.1016/j.bbamcr.2010.01.014] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Revised: 12/24/2009] [Accepted: 01/11/2010] [Indexed: 10/19/2022]
Abstract
The regulation of the actin cytoskeleton is a key process for the stability and motility of eukaryotic cells. Besides the Arp2/3 complex and its nucleation promoting factors, WH2 domain-containing proteins and a diverse family of formin proteins have recently been recognized as actin nucleators and potent polymerization factors of actin filaments. Formins are defined by the presence of a catalytic formin homology 2 (FH2) domain, yet, the modular domain architecture appears significantly different for the eight formin families identified in humans. A diverse picture of protein localization, interaction partners and cell specific regulation emerged, suggesting various functions of formins in the building and maintenance of actin filaments. This review focuses on the domain architecture of human formins, the regulation mechanisms of their activation and the diversity in formin cellular functions.
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Affiliation(s)
- André Schönichen
- Max-Planck-Institut für Molekulare Physiologie, Abteilung Physikalische Biochemie, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
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Chesarone MA, DuPage AG, Goode BL. Unleashing formins to remodel the actin and microtubule cytoskeletons. Nat Rev Mol Cell Biol 2009; 11:62-74. [PMID: 19997130 DOI: 10.1038/nrm2816] [Citation(s) in RCA: 394] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Formins are highly conserved proteins that have essential roles in remodelling the actin and microtubule cytoskeletons to influence eukaryotic cell shape and behaviour. Recent work has identified numerous cellular factors that locally recruit, activate or inactivate formins to bridle and unleash their potent effects on actin nucleation and elongation. The effects of formins on microtubules have also begun to be described, which places formins in a prime position to coordinate actin and microtubule dynamics. The emerging complexity in the mechanisms governing formins mirrors the wide range of essential functions that they perform in cell motility, cell division and cell and tissue morphogenesis.
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Affiliation(s)
- Melissa A Chesarone
- Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
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