401
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Gasilina A, Vitali T, Luo R, Jian X, Randazzo PA. The ArfGAP ASAP1 Controls Actin Stress Fiber Organization via Its N-BAR Domain. iScience 2019; 22:166-180. [PMID: 31785555 PMCID: PMC6889188 DOI: 10.1016/j.isci.2019.11.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/30/2019] [Accepted: 11/06/2019] [Indexed: 12/11/2022] Open
Abstract
ASAP1 is a multi-domain ArfGAP that controls cell migration, spreading, and focal adhesion dynamics. Although its GAP activity contributes to remodeling of the actin cytoskeleton, it does not fully explain all cellular functions of ASAP1. Here we find that ASAP1 regulates actin filament assembly directly through its N-BAR domain and controls stress fiber maintenance. ASAP1 depletion caused defects in stress fiber organization. Conversely, overexpression of ASAP1 enhanced actin remodeling. The BAR-PH fragment was sufficient to affect actin. ASAP1 with the BAR domain replaced with the BAR domain of the related ACAP1 did not affect actin. The BAR-PH tandem of ASAP1 bound and bundled actin filaments directly, whereas the presence of the ArfGAP and the C-terminal linker/SH3 domain reduced binding and bundling of filaments by BAR-PH. Together these data provide evidence that ASAP1 may regulate the actin cytoskeleton through direct interaction of the BAR-PH domain with actin filaments.
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Affiliation(s)
- Anjelika Gasilina
- Section on Regulation of Ras Superfamily, Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bldg. 37, Rm. 2042, Bethesda, MD 20892, USA; Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC 20007, USA
| | - Teresa Vitali
- Section on Regulation of Ras Superfamily, Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bldg. 37, Rm. 2042, Bethesda, MD 20892, USA
| | - Ruibai Luo
- Section on Regulation of Ras Superfamily, Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bldg. 37, Rm. 2042, Bethesda, MD 20892, USA
| | - Xiaoying Jian
- Section on Regulation of Ras Superfamily, Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bldg. 37, Rm. 2042, Bethesda, MD 20892, USA
| | - Paul A Randazzo
- Section on Regulation of Ras Superfamily, Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bldg. 37, Rm. 2042, Bethesda, MD 20892, USA.
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402
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Dialynas G, Delabaere L, Chiolo I. Arp2/3 and Unc45 maintain heterochromatin stability in Drosophila polytene chromosomes. Exp Biol Med (Maywood) 2019; 244:1362-1371. [PMID: 31364400 PMCID: PMC6880141 DOI: 10.1177/1535370219862282] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 06/18/2019] [Indexed: 12/31/2022] Open
Abstract
Repairing DNA double-strand breaks is particularly challenging in pericentromeric heterochromatin, where the abundance of repeated sequences exacerbates the risk of ectopic recombination. In Drosophila Kc cells, accurate homologous recombination repair of heterochromatic double-strand breaks relies on the relocalization of repair sites to the nuclear periphery before Rad51 recruitment and strand invasion. This movement is driven by Arp2/3-dependent nuclear actin filaments and myosins’ ability to walk along them. Conserved mechanisms enable the relocalization of heterochromatic repair sites in mouse cells, and defects in these pathways lead to massive ectopic recombination in heterochromatin and chromosome rearrangements. In Drosophila polytene chromosomes, extensive DNA movement is blocked by a stiff structure of chromosome bundles. Repair pathways in this context are poorly characterized, and whether heterochromatic double-strand breaks relocalize in these cells is unknown. Here, we show that damage in heterochromatin results in relaxation of the heterochromatic chromocenter, consistent with a dynamic response. Arp2/3, the Arp2/3 activator Scar, and the myosin activator Unc45, are required for heterochromatin stability in polytene cells, suggesting that relocalization enables heterochromatin repair also in this tissue. Together, these studies reveal critical roles for actin polymerization and myosin motors in heterochromatin repair and genome stability across different organisms and tissue types.
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Affiliation(s)
- George Dialynas
- Department of Molecular and Computational Biology,
University
of Southern California, Los Angeles
90089, USA
| | - Laetitia Delabaere
- Department of Molecular and Computational Biology,
University
of Southern California, Los Angeles
90089, USA
| | - Irene Chiolo
- Department of Molecular and Computational Biology,
University
of Southern California, Los Angeles
90089, USA
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403
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Argentati C, Morena F, Tortorella I, Bazzucchi M, Porcellati S, Emiliani C, Martino S. Insight into Mechanobiology: How Stem Cells Feel Mechanical Forces and Orchestrate Biological Functions. Int J Mol Sci 2019; 20:E5337. [PMID: 31717803 PMCID: PMC6862138 DOI: 10.3390/ijms20215337] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 10/23/2019] [Accepted: 10/25/2019] [Indexed: 12/12/2022] Open
Abstract
The cross-talk between stem cells and their microenvironment has been shown to have a direct impact on stem cells' decisions about proliferation, growth, migration, and differentiation. It is well known that stem cells, tissues, organs, and whole organisms change their internal architecture and composition in response to external physical stimuli, thanks to cells' ability to sense mechanical signals and elicit selected biological functions. Likewise, stem cells play an active role in governing the composition and the architecture of their microenvironment. Is now being documented that, thanks to this dynamic relationship, stemness identity and stem cell functions are maintained. In this work, we review the current knowledge in mechanobiology on stem cells. We start with the description of theoretical basis of mechanobiology, continue with the effects of mechanical cues on stem cells, development, pathology, and regenerative medicine, and emphasize the contribution in the field of the development of ex-vivo mechanobiology modelling and computational tools, which allow for evaluating the role of forces on stem cell biology.
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Affiliation(s)
- Chiara Argentati
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via del Giochetto, 06126 Perugia, Italy; (C.A.); (F.M.); (I.T.); (M.B.); (S.P.); (C.E.)
| | - Francesco Morena
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via del Giochetto, 06126 Perugia, Italy; (C.A.); (F.M.); (I.T.); (M.B.); (S.P.); (C.E.)
| | - Ilaria Tortorella
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via del Giochetto, 06126 Perugia, Italy; (C.A.); (F.M.); (I.T.); (M.B.); (S.P.); (C.E.)
| | - Martina Bazzucchi
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via del Giochetto, 06126 Perugia, Italy; (C.A.); (F.M.); (I.T.); (M.B.); (S.P.); (C.E.)
| | - Serena Porcellati
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via del Giochetto, 06126 Perugia, Italy; (C.A.); (F.M.); (I.T.); (M.B.); (S.P.); (C.E.)
| | - Carla Emiliani
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via del Giochetto, 06126 Perugia, Italy; (C.A.); (F.M.); (I.T.); (M.B.); (S.P.); (C.E.)
- CEMIN, Center of Excellence on Nanostructured Innovative Materials, Via del Giochetto, 06126 Perugia, Italy
| | - Sabata Martino
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via del Giochetto, 06126 Perugia, Italy; (C.A.); (F.M.); (I.T.); (M.B.); (S.P.); (C.E.)
- CEMIN, Center of Excellence on Nanostructured Innovative Materials, Via del Giochetto, 06126 Perugia, Italy
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404
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Bryce NS, Failes TW, Stehn JR, Baker K, Zahler S, Arzhaeva Y, Bischof L, Lyons C, Dedova I, Arndt GM, Gaus K, Goult BT, Hardeman EC, Gunning PW, Lock JG. High-Content Imaging of Unbiased Chemical Perturbations Reveals that the Phenotypic Plasticity of the Actin Cytoskeleton Is Constrained. Cell Syst 2019; 9:496-507.e5. [PMID: 31606369 DOI: 10.1016/j.cels.2019.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 07/08/2019] [Accepted: 09/06/2019] [Indexed: 12/27/2022]
Abstract
Although F-actin has a large number of binding partners and regulators, the number of phenotypic states available to the actin cytoskeleton is unknown. Here, we quantified 74 features defining filamentous actin (F-actin) and cellular morphology in >25 million cells after treatment with a library of 114,400 structurally diverse compounds. After reducing the dimensionality of these data, only ∼25 recurrent F-actin phenotypes emerged, each defined by distinct quantitative features that could be machine learned. We identified 2,003 unknown compounds as inducers of actin-related phenotypes, including two that directly bind the focal adhesion protein, talin. Moreover, we observed that compounds with distinct molecular mechanisms could induce equivalent phenotypes and that initially divergent cellular responses could converge over time. These findings suggest a conceptual parallel between the actin cytoskeleton and gene regulatory networks, where the theoretical plasticity of interactions is nearly infinite, yet phenotypes in vivo are constrained into a limited subset of practicable configurations.
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Affiliation(s)
- Nicole S Bryce
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Tim W Failes
- Australian Cancer Research Foundation Drug Discovery Centre, Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Justine R Stehn
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Karen Baker
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
| | - Stefan Zahler
- Department of Pharmacy, Ludwig-Maximilians-University, Munich, Germany
| | - Yulia Arzhaeva
- Quantitative Imaging Research Team, CSIRO Data 61, Marsfield, NSW, Australia
| | - Leanne Bischof
- Quantitative Imaging Research Team, CSIRO Data 61, Marsfield, NSW, Australia
| | - Ciaran Lyons
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Irina Dedova
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Greg M Arndt
- Australian Cancer Research Foundation Drug Discovery Centre, Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Katharina Gaus
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; EMBL Australia Node in Single Molecule Science, UNSW Sydney, Sydney, NSW 2052, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Benjamin T Goult
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
| | - Edna C Hardeman
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Peter W Gunning
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - John G Lock
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia.
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405
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Unusual dynamics of the divergent malaria parasite PfAct1 actin filament. Proc Natl Acad Sci U S A 2019; 116:20418-20427. [PMID: 31548388 DOI: 10.1073/pnas.1906600116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Gliding motility and host cell invasion by the apicomplexan parasite Plasmodium falciparum (Pf), the causative agent of malaria, is powered by a macromolecular complex called the glideosome that lies between the parasite plasma membrane and the inner membrane complex. The glideosome core consists of a single-headed class XIV myosin PfMyoA and a divergent actin PfAct1. Here we use total internal reflection fluorescence microscopy to visualize growth of individual unstabilized PfAct1 filaments as a function of time, an approach not previously used with this actin isoform. Although PfAct1 was thought to be incapable of forming long filaments, filaments grew as long as 30 µm. Polymerization occurs via a nucleation-elongation mechanism, but with an ∼4 µM critical concentration, an order-of-magnitude higher than for skeletal actin. Protomers disassembled from both the barbed and pointed ends of the actin filament with similar fast kinetics of 10 to 15 subunits/s. Rapid treadmilling, where the barbed end of the filament grows and the pointed end shrinks while maintaining an approximately constant filament length, was visualized near the critical concentration. Once ATP has been hydrolyzed to ADP, the filament becomes very unstable, resulting in total dissolution in <40 min. Dynamics at the filament ends are suppressed in the presence of inorganic phosphate or more efficiently by BeFX A chimeric PfAct1 with a mammalian actin D-loop forms a more stable filament. These unusual dynamic properties distinguish PfAct1 from more canonical actins, and likely contribute to the difficultly in visualizing PfAct1 filaments in the parasite.
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406
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Törnroth-Horsefield S. Phosphorylation of human AQP2 and its role in trafficking. VITAMINS AND HORMONES 2019; 112:95-117. [PMID: 32061351 DOI: 10.1016/bs.vh.2019.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Human Aquaporin 2 (AQP2) is a membrane-bound water channel found in the kidney collecting duct whose regulation by trafficking plays a key role in regulating urine volume. AQP2 trafficking is tightly controlled by the pituitary hormone arginine vasopressin (AVP), which stimulates translocation of AQP2 residing in storage vesicles to the apical membrane. The AVP-dependent translocation of AQP2 to and from the apical membrane is controlled by multiple phosphorylation sites in the AQP2 C-terminus, the phosphorylation of which alters its affinity to proteins within the cellular membrane protein trafficking machinery. The aim of this chapter is to provide a summary of what is currently known about AVP-mediated AQP2 trafficking, dissecting the roles of individual phosphorylation sites, kinases and phosphatases and interacting proteins. From this, the picture of an immensely complex process emerges, of which many structural and molecular details remains to be elucidated.
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407
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Hansson B, Morén B, Fryklund C, Vliex L, Wasserstrom S, Albinsson S, Berger K, Stenkula KG. Adipose cell size changes are associated with a drastic actin remodeling. Sci Rep 2019; 9:12941. [PMID: 31506540 PMCID: PMC6736966 DOI: 10.1038/s41598-019-49418-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 08/23/2019] [Indexed: 12/21/2022] Open
Abstract
Adipose tissue plays a major role in regulating whole-body insulin sensitivity and energy metabolism. To accommodate surplus energy, the tissue rapidly expands by increasing adipose cell size (hypertrophy) and cell number (hyperplasia). Previous studies have shown that enlarged, hypertrophic adipocytes are less responsive to insulin, and that adipocyte size could serve as a predictor for the development of type 2 diabetes. In the present study, we demonstrate that changes in adipocyte size correlate with a drastic remodeling of the actin cytoskeleton. Expansion of primary adipocytes following 2 weeks of high-fat diet (HFD)-feeding in C57BL6/J mice was associated with a drastic increase in filamentous (F)-actin as assessed by fluorescence microscopy, increased Rho-kinase activity, and changed expression of actin-regulating proteins, favoring actin polymerization. At the same time, increased cell size was associated with impaired insulin response, while the interaction between the cytoskeletal scaffolding protein IQGAP1 and insulin receptor substrate (IRS)-1 remained intact. Reversed feeding from HFD to chow restored cell size, insulin response, expression of actin-regulatory proteins and decreased the amount of F-actin filaments. Together, we report a drastic cytoskeletal remodeling during adipocyte expansion, a process which could contribute to deteriorating adipocyte function.
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Affiliation(s)
- Björn Hansson
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Björn Morén
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Claes Fryklund
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Lars Vliex
- Lund University, Department of Experimental Medical Science, Lund, Sweden.,Maastricht University, Faculty of Health, Medicine and Life Sciences, Maastricht, The Netherlands
| | | | | | - Karin Berger
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Karin G Stenkula
- Lund University, Department of Experimental Medical Science, Lund, Sweden.
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408
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Lee M, Kang EH. Molecular dynamics study of interactions between polymorphic actin filaments and gelsolin segment-1. Proteins 2019; 88:385-392. [PMID: 31498927 DOI: 10.1002/prot.25813] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 08/22/2019] [Accepted: 09/04/2019] [Indexed: 11/08/2022]
Abstract
The assembly of protein actin into double-helical filaments promotes many eukaryotic cellular processes that are regulated by actin-binding proteins (ABPs). Actin filaments can adopt multiple conformations, known as structural polymorphism, which possibly influences the interaction between filaments and ABPs. Gelsolin is a Ca2+ -regulated ABP that severs and caps actin filaments. Gelsolin binding modulates filament structure; however, it is not known how polymorphic actin filament structures influence an interaction of gelsolin S1 with the barbed-end of filament. Herein, we investigated how polymorphic structures of actin filaments affect the interactions near interfaces between the gelsolin segment 1 (S1) domain and the filament barbed-end. Using all-atom molecular dynamics simulations, we demonstrate that different tilted states of subunits modulate gelsolin S1 interactions with the barbed-end of polymorphic filaments. Hydrogen bonding and interaction energy at the filament-gelsolin S1 interface indicate distinct conformations of filament barbed ends, resulting in different interactions of gelsolin S1. This study demonstrates that filament's structural multiplicity plays important roles in the interactions of actin with ABPs.
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Affiliation(s)
- Myeongsang Lee
- NanoScience Technology Center, University of Central Florida, Orlando, Florida
| | - Ellen H Kang
- NanoScience Technology Center, University of Central Florida, Orlando, Florida.,Department of Physics, University of Central Florida, Orlando, Florida.,Department of Materials Science and Engineering, University of Central Florida, Orlando, Florida
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409
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Shrivastava S, Sarkar P, Preira P, Salomé L, Chattopadhyay A. Role of Actin Cytoskeleton in Dynamics and Function of the Serotonin 1A Receptor. Biophys J 2019; 118:944-956. [PMID: 31606121 DOI: 10.1016/j.bpj.2019.08.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/13/2019] [Accepted: 08/29/2019] [Indexed: 12/19/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are important membrane proteins in higher eukaryotes that carry out a vast array of cellular signaling and act as major drug targets. The serotonin1A receptor is a prototypical member of the GPCR family and is implicated in neuropsychiatric disorders such as anxiety and depression, besides serving as an important drug target. With an overall goal of exploring the functional consequence of altered receptor dynamics, in this work, we probed the role of the actin cytoskeleton in the dynamics, ligand binding, and signaling of the serotonin1A receptor. We monitored receptor dynamics utilizing single particle tracking, which provides information on relative distribution of receptors in various diffusion modes in addition to diffusion coefficient. We show here that the short-term diffusion coefficient of the receptor increases upon actin destabilization by cytochalasin D. In addition, analysis of individual trajectories shows that there are changes in relative populations of receptors undergoing various types of diffusion upon actin destabilization. The release of dynamic constraint was evident by an increase in the radius of confinement of the receptor upon actin destabilization. The functional implication of such actin destabilization was manifested as an increase in specific agonist binding and downstream signaling, monitored by measuring reduction in cellular cAMP levels. These results bring out the interdependence of GPCR dynamics with cellular signaling.
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Affiliation(s)
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Pascal Preira
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Laurence Salomé
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France.
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410
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Caridi CP, Plessner M, Grosse R, Chiolo I. Nuclear actin filaments in DNA repair dynamics. Nat Cell Biol 2019; 21:1068-1077. [PMID: 31481797 PMCID: PMC6736642 DOI: 10.1038/s41556-019-0379-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 07/24/2019] [Indexed: 02/06/2023]
Abstract
Recent development of innovative tools for live imaging of actin filaments (F-actin) enabled the detection of surprising nuclear structures responding to various stimuli, challenging previous models that actin is substantially monomeric in the nucleus. We review these discoveries, focusing on double-strand break (DSB) repair responses. These studies revealed a remarkable network of nuclear filaments and regulatory mechanisms coordinating chromatin dynamics with repair progression and led to a paradigm shift by uncovering the directed movement of repair sites.
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Affiliation(s)
| | - Matthias Plessner
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg im Breisgau, Germany
- CIBSS - Centre for Integrative Biological Signaling Studies, University of Freiburg, Freiburg im Breisgau, Germany
| | - Robert Grosse
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg im Breisgau, Germany
- CIBSS - Centre for Integrative Biological Signaling Studies, University of Freiburg, Freiburg im Breisgau, Germany
| | - Irene Chiolo
- Molecular and Computational Biology Department, University of Southern California, Los Angeles, CA, USA.
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411
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D'Amore C, Salizzato V, Borgo C, Cesaro L, Pinna LA, Salvi M. A Journey through the Cytoskeleton with Protein Kinase CK2. Curr Protein Pept Sci 2019; 20:547-562. [PMID: 30659536 DOI: 10.2174/1389203720666190119124846] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/21/2018] [Accepted: 01/09/2019] [Indexed: 01/15/2023]
Abstract
Substrate pleiotropicity, a very acidic phosphorylation consensus sequence, and an apparent uncontrolled activity, are the main features of CK2, a Ser/Thr protein kinase that is required for a plethora of cell functions. Not surprisingly, CK2 appears to affect cytoskeletal structures and correlated functions such as cell shape, mechanical integrity, cell movement and division. This review outlines our current knowledge of how CK2 regulates cytoskeletal structures, and discusses involved pathways and molecular mechanisms.
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Affiliation(s)
- Claudio D'Amore
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
| | - Valentina Salizzato
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy.,CNR Institute of Neurosciences, Via U. Bassi 58/B, Padova, Italy
| | - Christian Borgo
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
| | - Luca Cesaro
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
| | - Lorenzo A Pinna
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy.,CNR Institute of Neurosciences, Via U. Bassi 58/B, Padova, Italy
| | - Mauro Salvi
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
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412
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The Cytoskeleton of the Retinal Pigment Epithelium: from Normal Aging to Age-Related Macular Degeneration. Int J Mol Sci 2019; 20:ijms20143578. [PMID: 31336621 PMCID: PMC6678077 DOI: 10.3390/ijms20143578] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/15/2019] [Accepted: 07/18/2019] [Indexed: 12/15/2022] Open
Abstract
The retinal pigment epithelium (RPE) is a unique epithelium, with major roles which are essential in the visual cycle and homeostasis of the outer retina. The RPE is a monolayer of polygonal and pigmented cells strategically placed between the neuroretina and Bruch membrane, adjacent to the fenestrated capillaries of the choriocapillaris. It shows strong apical (towards photoreceptors) to basal/basolateral (towards Bruch membrane) polarization. Multiple functions are bound to a complex structure of highly organized and polarized intracellular components: the cytoskeleton. A strong connection between the intracellular cytoskeleton and extracellular matrix is indispensable to maintaining the function of the RPE and thus, the photoreceptors. Impairments of these intracellular structures and the regular architecture they maintain often result in a disrupted cytoskeleton, which can be found in many retinal diseases, including age-related macular degeneration (AMD). This review article will give an overview of current knowledge on the molecules and proteins involved in cytoskeleton formation in cells, including RPE and how the cytoskeleton is affected under stress conditions—especially in AMD.
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413
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Schrank B, Gautier J. Assembling nuclear domains: Lessons from DNA repair. J Cell Biol 2019; 218:2444-2455. [PMID: 31324649 PMCID: PMC6683749 DOI: 10.1083/jcb.201904202] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/24/2019] [Accepted: 06/27/2019] [Indexed: 12/14/2022] Open
Abstract
Schrank and Gautier discuss the generation and function of nuclear domains during DNA repair with a special focus on nuclear actin polymerization. Eukaryotic nuclei are organized into nuclear domains that unite loci sharing a common function. These domains are essential for diverse processes including (1) the formation of topologically associated domains (TADs) that coordinate replication and transcription, (2) the formation of specialized transcription and splicing factories, and (3) the clustering of DNA double-strand breaks (DSBs), which concentrates damaged DNA for repair. The generation of nuclear domains requires forces that are beginning to be identified. In the case of DNA DSBs, DNA movement and clustering are driven by actin filament nucleators. Furthermore, RNAs and low-complexity protein domains such as RNA-binding proteins also accumulate around sites of transcription and repair. The link between liquid–liquid phase separation and actin nucleation in the formation of nuclear domains is still unknown. This review discusses DSB repair domain formation as a model for functional nuclear domains in other genomic contexts.
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Affiliation(s)
- Benjamin Schrank
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, NY
| | - Jean Gautier
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, NY
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414
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Abstract
DNA double-strand breaks (DSBs) are particularly challenging to repair in pericentromeric heterochromatin because of the increased risk of aberrant recombination in highly repetitive sequences. Recent studies have identified specialized mechanisms enabling 'safe' homologous recombination (HR) repair in heterochromatin. These include striking nuclear actin filaments (F-actin) and myosins that drive the directed motion of repair sites to the nuclear periphery for 'safe' repair. Here, we summarize our current understanding of the mechanisms involved, and propose how they might operate in the context of a phase-separated environment.
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415
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Vidaud C, Robert M, Paredes E, Ortega R, Avazeri E, Jing L, Guigonis JM, Bresson C, Malard V. Deciphering the uranium target proteins in human dopaminergic SH-SY5Y cells. Arch Toxicol 2019; 93:2141-2154. [DOI: 10.1007/s00204-019-02497-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 06/17/2019] [Indexed: 12/11/2022]
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416
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Kumpula EP, Lopez AJ, Tajedin L, Han H, Kursula I. Atomic view into Plasmodium actin polymerization, ATP hydrolysis, and fragmentation. PLoS Biol 2019; 17:e3000315. [PMID: 31199804 PMCID: PMC6599135 DOI: 10.1371/journal.pbio.3000315] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 06/28/2019] [Accepted: 05/23/2019] [Indexed: 11/18/2022] Open
Abstract
Plasmodium actins form very short filaments and have a noncanonical link between ATP hydrolysis and polymerization. Long filaments are detrimental to the parasites, but the structural factors constraining Plasmodium microfilament lengths have remained unknown. Using high-resolution crystallography, we show that magnesium binding causes a slight flattening of the Plasmodium actin I monomer, and subsequent phosphate release results in a more twisted conformation. Thus, the Mg-bound monomer is closer in conformation to filamentous (F) actin than the Ca form, and this likely facilitates polymerization. A coordinated potassium ion resides in the active site during hydrolysis and leaves together with the phosphate, a process governed by the position of the Arg178/Asp180-containing A loop. Asp180 interacts with either Lys270 or His74, depending on the protonation state of the histidine, while Arg178 links the inner and outer domains (ID and OD) of the actin protomer. Hence, the A loop acts as a switch between stable and unstable filament conformations, the latter leading to fragmentation. Our data provide a comprehensive model for polymerization, ATP hydrolysis and phosphate release, and fragmentation of parasite microfilaments. Similar mechanisms may well exist in canonical actins, although fragmentation is much less favorable due to several subtle sequence differences as well as the methylation of His73, which is absent on the corresponding His74 in Plasmodium actin I. A detailed mechanistic study of malaria parasite actins reveals at the atomic level how they polymerize, hydrolyze ATP, and are fragmented to keep actin filament lengths short enough for parasite survival.
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Affiliation(s)
- Esa-Pekka Kumpula
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Andrea J. Lopez
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Leila Tajedin
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Huijong Han
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
- European XFEL GmbH, Schenefeld, Germany
| | - Inari Kursula
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
- Department of Biomedicine, University of Bergen, Bergen, Norway
- European XFEL GmbH, Schenefeld, Germany
- * E-mail:
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417
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Abstract
The shape of most animal cells is controlled by the actin cortex, a thin network of dynamic actin filaments (F-actin) situated just beneath the plasma membrane. The cortex is held far from equilibrium by both active stresses and polymer turnover: Molecular motors drive deformations required for cell morphogenesis, while actin-filament disassembly dynamics relax stress and facilitate cortical remodeling. While many aspects of actin-cortex mechanics are well characterized, a mechanistic understanding of how nonequilibrium actin turnover contributes to stress relaxation is still lacking. To address this, we developed a reconstituted in vitro system of entangled F-actin, wherein the steady-state length and turnover rate of F-actin are controlled by the actin regulatory proteins cofilin, profilin, and formin, which sever, recycle, and assemble filaments, respectively. Cofilin-mediated severing accelerates the turnover and spatial reorganization of F-actin, without significant changes to filament length. We demonstrate that cofilin-mediated severing is a single-timescale mode of stress relaxation that tunes the low-frequency viscosity over two orders of magnitude. These findings serve as the foundation for understanding the mechanics of more physiological F-actin networks with turnover and inform an updated microscopic model of single-filament turnover. They also demonstrate that polymer activity, in the form of ATP hydrolysis on F-actin coupled to nucleotide-dependent cofilin binding, is sufficient to generate a form of active matter wherein asymmetric filament disassembly preserves filament number despite sustained severing.
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418
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Sizes of actin networks sharing a common environment are determined by the relative rates of assembly. PLoS Biol 2019; 17:e3000317. [PMID: 31181075 PMCID: PMC6586355 DOI: 10.1371/journal.pbio.3000317] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 06/20/2019] [Accepted: 05/28/2019] [Indexed: 12/31/2022] Open
Abstract
Within the cytoplasm of a single cell, several actin networks can coexist with distinct sizes, geometries, and protein compositions. These actin networks assemble in competition for a limited pool of proteins present in a common cellular environment. To predict how two distinct networks of actin filaments control this balance, the simultaneous assembly of actin-related protein 2/3 (Arp2/3)-branched networks and formin-linear networks of actin filaments around polystyrene microbeads was investigated with a range of actin accessory proteins (profilin, capping protein, actin-depolymerizing factor [ADF]/cofilin, and tropomyosin). Accessory proteins generally affected actin assembly rates for the distinct networks differently. These effects at the scale of individual actin networks were surprisingly not always correlated with corresponding loss-of-function phenotypes in cells. However, our observations agreed with a global interpretation, which compared relative actin assembly rates of individual actin networks. This work supports a general model in which the size of distinct actin networks is determined by their relative capacity to assemble in a common and competing environment. A biomimetic assay using polystyrene beads compares the rates of actin assembly on linear and branched networks, revealing how the size of rival actin networks in cells is regulated by their relative capacity to assemble in a common environment.
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419
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Zhang R, Qu X, Zhang M, Jiang Y, Dai A, Zhao W, Cao D, Lan Y, Yu R, Wang H, Huang S. The Balance between Actin-Bundling Factors Controls Actin Architecture in Pollen Tubes. iScience 2019; 16:162-176. [PMID: 31181400 PMCID: PMC6556835 DOI: 10.1016/j.isci.2019.05.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/29/2019] [Accepted: 05/21/2019] [Indexed: 11/19/2022] Open
Abstract
How actin-bundling factors cooperatively regulate shank-localized actin bundles remains largely unexplored. Here we demonstrate that FIM5 and PLIM2a/PLIM2b decorate shank-localized actin bundles and that loss of function of PLIM2a and/or PLIM2b suppresses phenotypes associated with fim5 mutants. Specifically, knockout of PLIM2a and/or PLIM2b partially suppresses the disorganized actin bundle and intracellular trafficking phenotype in fim5 pollen tubes. PLIM2a/PLIM2b generates thick but loosely packed actin bundles, whereas FIM5 generates thin but tight actin bundles that tend to be cross-linked into networks in vitro. Furthermore, PLIM2a/PLIM2b and FIM5 compete for binding to actin filaments in vitro, and PLIM2a/PLIM2b decorate disorganized actin bundles in fim5 pollen tubes. These data together suggest that the disorganized actin bundles in fim5 mutants are at least partially due to gain of function of PLIM2a/PLIM2b. Our data suggest that the balance between FIM5 and PLIM2a/PLIM2b is crucial for the normal bundling and organization of shank-localized actin bundles in pollen tubes. The transcription of PLIM2a and PLIM2b is upregulated in fim5 pollen tubes Downregulation of PLIM2a and/or PLIM2b suppresses the defects in fim5 pollen tubes Both FIM5 and PLIM2a/PLIM2b decorate shank-localized actin filaments FIM5 can inhibit the binding of PLIM2a and PLIM2b to actin filaments
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Affiliation(s)
- Ruihui Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaolu Qu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Meng Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yuxiang Jiang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Anbang Dai
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wanying Zhao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Dai Cao
- School of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yaxian Lan
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Rong Yu
- School of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hongwei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
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420
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Wurzer H, Hoffmann C, Al Absi A, Thomas C. Actin Cytoskeleton Straddling the Immunological Synapse between Cytotoxic Lymphocytes and Cancer Cells. Cells 2019; 8:cells8050463. [PMID: 31100864 PMCID: PMC6563383 DOI: 10.3390/cells8050463] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/08/2019] [Accepted: 05/13/2019] [Indexed: 02/06/2023] Open
Abstract
The immune system is a fundamental part of the tumor microenvironment. In particular, cytotoxic lymphocytes, such as cytolytic T cells and natural killer cells, control tumor growth and disease progression by interacting and eliminating tumor cells. The actin cytoskeleton of cytotoxic lymphocytes engaged in an immunological synapse has received considerable research attention. It has been recognized as a central mediator of the formation and maturation of the immunological synapse, and its signaling and cytolytic activities. In comparison, fewer studies have explored the organization and function of actin filaments on the target cancer cell side of the immunological synapse. However, there is growing evidence that the actin cytoskeleton of cancer cells also undergoes extensive remodeling upon cytotoxic lymphocyte attack, and that such remodeling can alter physical and functional interactions at the immunological synapse. In this article, we review the current knowledge of actin organization and functions at both sides of the immunological synapse between cytotoxic lymphocytes and cancer cells, with particular focus on synapse formation, signaling and cytolytic activity, and immune evasion.
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Affiliation(s)
- Hannah Wurzer
- Cytoskeleton and Cancer Progression; Laboratory of Experimental Cancer Research, Department of Oncology 84 Val Fleuri, L-1526 Luxembourg City, Luxembourg.
- University of Luxembourg, Faculty of Science, Technology and Communication, 2 Avenue de l'Université, L-4365 Esch-sur-Alzette, Luxembourg.
| | - Céline Hoffmann
- Cytoskeleton and Cancer Progression; Laboratory of Experimental Cancer Research, Department of Oncology 84 Val Fleuri, L-1526 Luxembourg City, Luxembourg.
| | - Antoun Al Absi
- Cytoskeleton and Cancer Progression; Laboratory of Experimental Cancer Research, Department of Oncology 84 Val Fleuri, L-1526 Luxembourg City, Luxembourg.
- University of Strasbourg, 67081 Strasbourg, France.
| | - Clément Thomas
- Cytoskeleton and Cancer Progression; Laboratory of Experimental Cancer Research, Department of Oncology 84 Val Fleuri, L-1526 Luxembourg City, Luxembourg.
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421
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Lamson AR, Edelmaier CJ, Glaser MA, Betterton MD. Theory of Cytoskeletal Reorganization during Cross-Linker-Mediated Mitotic Spindle Assembly. Biophys J 2019; 116:1719-1731. [PMID: 31010665 PMCID: PMC6507341 DOI: 10.1016/j.bpj.2019.03.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/25/2019] [Accepted: 03/06/2019] [Indexed: 11/29/2022] Open
Abstract
Cells grow, move, and respond to outside stimuli by large-scale cytoskeletal reorganization. A prototypical example of cytoskeletal remodeling is mitotic spindle assembly, during which microtubules nucleate, undergo dynamic instability, bundle, and organize into a bipolar spindle. Key mechanisms of this process include regulated filament polymerization, cross-linking, and motor-protein activity. Remarkably, using passive cross-linkers, fission yeast can assemble a bipolar spindle in the absence of motor proteins. We develop a torque-balance model that describes this reorganization because of dynamic microtubule bundles, spindle-pole bodies, the nuclear envelope, and passive cross-linkers to predict spindle-assembly dynamics. We compare these results to those obtained with kinetic Monte Carlo-Brownian dynamics simulations, which include cross-linker-binding kinetics and other stochastic effects. Our results show that rapid cross-linker reorganization to microtubule overlaps facilitates cross-linker-driven spindle assembly, a testable prediction for future experiments. Combining these two modeling techniques, we illustrate a general method for studying cytoskeletal network reorganization.
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Affiliation(s)
- Adam R Lamson
- Department of Physics, University of Colorado, Boulder, Colorado
| | | | - Matthew A Glaser
- Department of Physics, University of Colorado, Boulder, Colorado
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422
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Malik-Garbi M, Ierushalmi N, Jansen S, Abu-Shah E, Goode BL, Mogilner A, Keren K. Scaling behaviour in steady-state contracting actomyosin networks. NATURE PHYSICS 2019; 15:509-516. [PMID: 31754369 PMCID: PMC6871652 DOI: 10.1038/s41567-018-0413-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 12/20/2018] [Indexed: 05/25/2023]
Abstract
Contractile actomyosin network flows are crucial for many cellular processes including cell division and motility, morphogenesis and transport. How local remodeling of actin architecture tunes stress production and dissipation and regulates large-scale network flows remains poorly understood. Here, we generate contracting actomyosin networks with rapid turnover in vitro, by encapsulating cytoplasmic Xenopus egg extracts into cell-sized 'water-in-oil' droplets. Within minutes, the networks reach a dynamic steady-state with continuous inward flow. The networks exhibit homogeneous, density-independent contraction for a wide range of physiological conditions, implying that the myosin-generated stress driving contraction and the effective network viscosity have similar density dependence. We further find that the contraction rate is roughly proportional to the network turnover rate, but this relation breaks down in the presence of excessive crosslinking or branching. Our findings suggest that cells use diverse biochemical mechanisms to generate robust, yet tunable, actin flows by regulating two parameters: turnover rate and network geometry.
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Affiliation(s)
- Maya Malik-Garbi
- Department of Physics, Technion- Israel Institute of Technology, Haifa 32000, Israel
| | - Niv Ierushalmi
- Department of Physics, Technion- Israel Institute of Technology, Haifa 32000, Israel
| | - Silvia Jansen
- Department of Biology, Brandeis University, Waltham, MA, USA
- Department of Cell Biology and Physiology, Washington University St. Louis, St. Louis, MO, USA
| | - Enas Abu-Shah
- Department of Physics, Technion- Israel Institute of Technology, Haifa 32000, Israel
- Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, UK
| | - Bruce L Goode
- Department of Biology, Brandeis University, Waltham, MA, USA
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York, NY 10012, USA
| | - Kinneret Keren
- Department of Physics, Technion- Israel Institute of Technology, Haifa 32000, Israel
- Network Biology Research Laboratories and Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel
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423
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Kang B, Jo S, Baek J, Nakamura F, Hwang W, Lee H. Role of mechanical flow for actin network organization. Acta Biomater 2019; 90:217-224. [PMID: 30928733 DOI: 10.1016/j.actbio.2019.03.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/28/2019] [Accepted: 03/26/2019] [Indexed: 11/30/2022]
Abstract
The major cytoskeletal protein actin forms complex networks to provide structural support and perform vital functions in cells. In vitro studies have revealed that the structure of the higher-order actin network is determined primarily by the type of actin binding protein (ABP). By comparison, there are far fewer studies about the role of the mechanical environment for the organization of the actin network. In particular, the duration over which cells reorganize their shape in response to functional demands is relatively short compared to the in vitro protein polymerization time, suggesting that such changes can influence the actin network formation. We hypothesize that mechanical flows in the cytoplasm generated by exogenous and endogenous stimulation play a key role in the spatiotemporal regulation of the actin architecture. To mimic cytoplasmic streaming, we generated a circulating flow using surface acoustic wave in a microfluidic channel and investigated its effect on the formation of networks by actin and ABPs. We found that the mechanical flow affected the orientation and thickness of actin bundles, depending on the type and concentration of ABPs. Our computational model shows that the extent of alignment and thickness of actin bundle are determined by the balance between flow-induced drag forces and the tendency of ABPs to crosslink actin filaments at given angles. These results suggest that local intracellular flows can affect the assembly dynamics and morphology of the actin cytoskeleton. STATEMENT OF SIGNIFICANCE: Spatiotemporal regulation of actin cytoskeleton structure is essential in many cellular functions. It has been shown that mechanical cues including an applied force and geometric boundary can alter the structural characteristics of actin network. However, even though the cytoplasm accounts for a large portion of the cell volume, the effect of the cytoplasmic streaming flow produced during cell dynamics on actin network organization has not been reported. In this study, we demonstrated that the mechanical flow exerted during actin network organization play an important role in determining the orientation and dimension of actin bundle network. Our result will be beneficial in understanding the mechanism of the actin network reorganization occurred during physiological and pathological processes.
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Affiliation(s)
- Byungjun Kang
- School of Mechanical Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Seunghan Jo
- School of Mechanical Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Jonghyeok Baek
- School of Mechanical Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Fumihiko Nakamura
- School of Pharmaceutical Science and Technology, Health Sciences Platform, Tianjin University, Tianjin 300072, China
| | - Wonmuk Hwang
- Departments of Biomedical Engineering, Materials Science & Engineering, and Physics & Astronomy, Texas A&M University, College Station, TX 77843, USA; School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, Republic of Korea
| | - Hyungsuk Lee
- School of Mechanical Engineering, Yonsei University, Seoul 03722, Republic of Korea.
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424
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Wang J, Nakamura F. Identification of Filamin A Mechanobinding Partner II: Fimbacin Is a Novel Actin Cross-Linking and Filamin A Binding Protein. Biochemistry 2019; 58:4737-4743. [PMID: 30990684 DOI: 10.1021/acs.biochem.9b00101] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Filamin A (FLNA), an actin cross-linking protein, acts as a mechanosensor and mechanotransducer by exposing the cryptic binding site on repeat 21 (R21) to interact with integrin. Here, we investigated if any other biological molecule interacts with the cryptic binding site. Using proteomics and an in silico screening for a FLNA-binding motif, we identified and characterized a protein termed fimbacin (filamin mechanobinding actin cross-linking protein), encoded in the LUZP1 gene, as a novel FLNA-binding partner. Fimbacin does not interact with canonical full-length FLNA, but the exposure of a cryptic integrin-binding site of FLNA R21 enables fimbacin to interact. We have identified two FLNA binding sites on fimbacin and determined critical amino acid residues for the interaction. We also found that fimbacin itself is a new actin cross-linking protein and mapped the actin-binding site on amino acid residues 400-500. Fimbacin oligomerizes (estimated as an octamer on size exclusion chromatography) through the amino-terminal domain that is predicted to be a coiled-coil to cross-link actin filaments. When expressed, fimbacin localized to actin stress fibers in tissue culture cells. Although the interaction with FLNA is not necessary for fimbacin to colocalize with F-actin, fluorescent recovery after photobleaching (FRAP) revealed that their interaction stabilizes fimbacin on the actin cytoskeleton and that inhibition of Rho-kinase, an upstream activator of myosin II, also decreases the interaction presumably due to a loss of internal mechanical stress. Taken together, these data identify fimbacin as a new actin cross-linking protein that interacts with the FLNA mechanosensing domain R21.
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Affiliation(s)
- Jiale Wang
- School of Pharmaceutical Science and Technology, Life Science Platform , Tianjin University , 92 Weijin Road, Nankai District , Tianjin , 300072 , China
| | - Fumihiko Nakamura
- School of Pharmaceutical Science and Technology, Life Science Platform , Tianjin University , 92 Weijin Road, Nankai District , Tianjin , 300072 , China
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425
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Meiring JCM, Bryce NS, Niño JLG, Gabriel A, Tay SS, Hardeman EC, Biro M, Gunning PW. Tropomyosin concentration but not formin nucleators mDia1 and mDia3 determines the level of tropomyosin incorporation into actin filaments. Sci Rep 2019; 9:6504. [PMID: 31019238 PMCID: PMC6482184 DOI: 10.1038/s41598-019-42977-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 04/11/2019] [Indexed: 12/31/2022] Open
Abstract
The majority of actin filaments in human cells exist as a co-polymer with tropomyosin, which determines the functionality of actin filaments in an isoform dependent manner. Tropomyosin isoforms are sorted to different actin filament populations and in yeast this process is determined by formins, however it remains unclear what process determines tropomyosin isoform sorting in mammalian cells. We have tested the roles of two major formin nucleators, mDia1 and mDia3, in the recruitment of specific tropomyosin isoforms in mammals. Despite observing poorer cell-cell attachments in mDia1 and mDia3 KD cells and an actin bundle organisation defect with mDia1 knock down; depletion of mDia1 and mDia3 individually and concurrently did not result in any significant impact on tropomyosin recruitment to actin filaments, as observed via immunofluorescence and measured via biochemical assays. Conversely, in the presence of excess Tpm3.1, the absolute amount of Tpm3.1-containing actin filaments is not fixed by actin filament nucleators but rather depends on the cell concentration of Tpm3.1. We conclude that mDia1 and mDia3 are not essential for tropomyosin recruitment and that tropomyosin incorporation into actin filaments is concentration dependent.
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Affiliation(s)
- Joyce C M Meiring
- Cellular and Genetic Medicine Unit, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Nicole S Bryce
- Cellular and Genetic Medicine Unit, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Jorge Luis Galeano Niño
- Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Antje Gabriel
- Cellular and Genetic Medicine Unit, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.,Pharmaceutical Biology, Center for Drug Research, Ludwig-Maximilians-Universität, Munich, Germany
| | - Szun S Tay
- Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Edna C Hardeman
- Cellular and Genetic Medicine Unit, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Maté Biro
- Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Peter W Gunning
- Cellular and Genetic Medicine Unit, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
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426
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The Cytoskeleton-A Complex Interacting Meshwork. Cells 2019; 8:cells8040362. [PMID: 31003495 PMCID: PMC6523135 DOI: 10.3390/cells8040362] [Citation(s) in RCA: 181] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/22/2022] Open
Abstract
The cytoskeleton of animal cells is one of the most complicated and functionally versatile structures, involved in processes such as endocytosis, cell division, intra-cellular transport, motility, force transmission, reaction to external forces, adhesion and preservation, and adaptation of cell shape. These functions are mediated by three classical cytoskeletal filament types, as follows: Actin, microtubules, and intermediate filaments. The named filaments form a network that is highly structured and dynamic, responding to external and internal cues with a quick reorganization that is orchestrated on the time scale of minutes and has to be tightly regulated. Especially in brain tumors, the cytoskeleton plays an important role in spreading and migration of tumor cells. As the cytoskeletal organization and regulation is complex and many-faceted, this review aims to summarize the findings about cytoskeletal filament types, including substructures formed by them, such as lamellipodia, stress fibers, and interactions between intermediate filaments, microtubules and actin. Additionally, crucial regulatory aspects of the cytoskeletal filaments and the formed substructures are discussed and integrated into the concepts of cell motility. Even though little is known about the impact of cytoskeletal alterations on the progress of glioma, a final point discussed will be the impact of established cytoskeletal alterations in the cellular behavior and invasion of glioma.
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427
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Sundararajan L, Stern J, Miller DM. Mechanisms that regulate morphogenesis of a highly branched neuron in C. elegans. Dev Biol 2019; 451:53-67. [PMID: 31004567 DOI: 10.1016/j.ydbio.2019.04.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 03/09/2019] [Accepted: 04/05/2019] [Indexed: 02/08/2023]
Abstract
The shape of an individual neuron is linked to its function with axons sending signals to other cells and dendrites receiving them. Although much is known of the mechanisms for axonal outgrowth, the striking complexity of dendritic architecture has hindered efforts to uncover pathways that direct dendritic branching. Here we review the results of an experimental strategy that exploits the power of genetic analysis and live cell imaging of the PVD sensory neuron in C. elegans to reveal key molecular drivers of dendrite morphogenesis.
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Affiliation(s)
- Lakshmi Sundararajan
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Jamie Stern
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - David M Miller
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA.
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428
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Dutta P, Jijumon AS, Mazumder M, Dileep D, Mukhopadhyay AK, Gourinath S, Maiti S. Presence of actin binding motif in VgrG-1 toxin of Vibrio cholerae reveals the molecular mechanism of actin cross-linking. Int J Biol Macromol 2019; 133:775-785. [PMID: 31002899 DOI: 10.1016/j.ijbiomac.2019.04.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/04/2019] [Accepted: 04/04/2019] [Indexed: 11/27/2022]
Abstract
Type VI secretion systems (T6SS) plays a crucial role in Vibrio cholerae mediated pathogenicity. Tip of T6SS is homologous to gp27/gp5 complex or tail spike of T4 bacteriophage. VgrG-1 of V. cholerae T6SS is unusual among other VgrG because its effector domain is trans-located into the cytosol of eukaryotic cells with an additional actin cross-linking domain (ACD) at its C terminal end. ACD of VgrG-1 (VgrG-1-ACD) causes T6SS dependent host cell cytotoxicity through actin cytoskeleton disruption to prevent bacterial engulfment by macrophages. ACD mediated actin cross-linking promotes survival of the bacteria in the small intestine of humans, along with other virulence factors; establishes successful infection with the onset of diarrhoea in humans. Our studies demonstrated VgrG-1-ACD can bind to actin besides actin cross-linking activity. Computational analysis of ACD revealed the presence of actin binding motif (ABM). Mutations in ABM lead to loss of actin binding in vitro. VgrG-1-ACD having the mutated ABM cannot cross-link actin efficiently in vitro and manifests less actin cytoskeleton disruption when transfected in HeLa cells.
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Affiliation(s)
- Priyanka Dutta
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India
| | - A S Jijumon
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India
| | | | - Drisya Dileep
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India
| | | | | | - Sankar Maiti
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India.
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429
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Regulation of Actin Dynamics in the C. elegans Somatic Gonad. J Dev Biol 2019; 7:jdb7010006. [PMID: 30897735 PMCID: PMC6473838 DOI: 10.3390/jdb7010006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 03/13/2019] [Accepted: 03/15/2019] [Indexed: 11/25/2022] Open
Abstract
The reproductive system of the hermaphroditic nematode C. elegans consists of a series of contractile cell types—including the gonadal sheath cells, the spermathecal cells and the spermatheca–uterine valve—that contract in a coordinated manner to regulate oocyte entry and exit of the fertilized embryo into the uterus. Contraction is driven by acto-myosin contraction and relies on the development and maintenance of specialized acto-myosin networks in each cell type. Study of this system has revealed insights into the regulation of acto-myosin network assembly and contractility in vivo.
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430
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Bryce NS, Hardeman EC, Gunning PW, Lock JG. Chemical biology approaches targeting the actin cytoskeleton through phenotypic screening. Curr Opin Chem Biol 2019; 51:40-47. [PMID: 30901618 DOI: 10.1016/j.cbpa.2019.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 02/05/2019] [Accepted: 02/12/2019] [Indexed: 12/29/2022]
Abstract
The actin cytoskeleton is dysregulated in cancer, yet this critical cellular machinery has not translated as a druggable clinical target due to cardio-toxic side-effects. Many actin regulators are also considered undruggable, being structural proteins lacking clear functional sites suitable for targeted drug design. In this review, we discuss opportunities and challenges associated with drugging the actin cytoskeleton through its structural regulators, taking tropomyosins as a target example. In particular, we highlight emerging data acquisition and analysis trends driving phenotypic, imaging-based compound screening. Finally, we consider how the confluence of these trends is now bringing functionally integral machineries such as the actin cytoskeleton, and associated structural regulatory proteins, into an expanded repertoire of druggable targets with previously unexploited clinical potential.
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Affiliation(s)
- Nicole S Bryce
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
| | - Edna C Hardeman
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
| | - Peter W Gunning
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia.
| | - John G Lock
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
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431
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Chou SZ, Pollard TD. Mechanism of actin polymerization revealed by cryo-EM structures of actin filaments with three different bound nucleotides. Proc Natl Acad Sci U S A 2019; 116:4265-4274. [PMID: 30760599 PMCID: PMC6410863 DOI: 10.1073/pnas.1807028115] [Citation(s) in RCA: 131] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We used cryo-electron microscopy (cryo-EM) to reconstruct actin filaments with bound AMPPNP (β,γ-imidoadenosine 5'-triphosphate, an ATP analog, resolution 3.1 Å), ADP-Pi (ADP with inorganic phosphate, resolution 3.1 Å), or ADP (resolution 3.6 Å). Subunits in the three filaments have similar backbone conformations, so assembly rather than ATP hydrolysis or phosphate dissociation is responsible for their flattened conformation in filaments. Polymerization increases the rate of ATP hydrolysis by changing the positions of the side chains of Q137 and H161 in the active site. Flattening during assembly also promotes interactions along both the long-pitch and short-pitch helices. In particular, conformational changes in subdomain 3 open up multiple favorable interactions with the DNase-I binding loop in subdomain 2 of the adjacent subunit. Subunits at the barbed end of the filament are likely to be in this favorable conformation, while monomers are not. This difference explains why filaments grow faster at the barbed end than the pointed end. When phosphate dissociates from ADP-Pi-actin through a backdoor channel, the conformation of the C terminus changes so it distorts the DNase binding loop, which allows cofilin binding, and a network of interactions among S14, H73, G74, N111, R177, and G158 rearranges to open the phosphate release site.
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Affiliation(s)
- Steven Z Chou
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103
| | - Thomas D Pollard
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103;
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103
- Department of Cell Biology, Yale University, New Haven, CT 06520-8103
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432
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Solís C, Russell B. CapZ integrates several signaling pathways in response to mechanical stiffness. J Gen Physiol 2019; 151:660-669. [PMID: 30808692 PMCID: PMC6504289 DOI: 10.1085/jgp.201812199] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/13/2018] [Accepted: 02/06/2019] [Indexed: 12/22/2022] Open
Abstract
Changes in mechanical load, hormones, or metabolic stress provoke remodeling of the actin-based thin filaments within muscle fibers. Solís and Russell show that several signaling pathways converge at the actin-capping protein CapZ to regulate muscle fiber growth in response to mechanical stiffness and neurohumoral signaling. Muscle adaptation is a response to physiological demand elicited by changes in mechanical load, hormones, or metabolic stress. Cytoskeletal remodeling processes in many cell types are thought to be primarily regulated by thin filament formation due to actin-binding accessory proteins, such as the actin-capping protein. Here, we hypothesize that in muscle, the actin-capping protein (named CapZ) integrates signaling by a variety of pathways, including phosphorylation and phosphatidylinositol 4,5-bisphosphate (PIP2) binding, to regulate muscle fiber growth in response to mechanical load. To test this hypothesis, we assess mechanotransduction signaling that regulates muscle growth using neonatal rat ventricular myocytes cultured on substrates with the stiffness of the healthy myocardium (10 kPa), fibrotic myocardium (100 kPa), or glass. We investigate how PIP2 signaling affects CapZ using the PIP2 sequestering agent neomycin and the effect of PKC-mediated CapZ phosphorylation using the PKC-activating drug phorbol 12-myristate 13-acetate (PMA). Molecular simulations suggest that close interactions between PIP2 and the β-tentacle of CapZ are modified by phosphorylation at T267. Fluorescence recovery after photobleaching (FRAP) demonstrates that the kinetic binding constant of CapZ to sarcomeric thin filaments in living muscle cells increases with stiffness or PMA treatment but is diminished by PIP2 reduction. Furthermore, CapZ with a deletion of the β-tentacle that lacks the phosphorylation site T267 shows increased FRAP kinetics with lack of sensitivity to PMA treatment or PIP2 reduction. Förster resonance energy transfer (FRET) probes the molecular interactions between PIP2 and CapZ, which are decreased by PIP2 availability or by the β-tentacle truncation. These data suggest that CapZ is bound to actin tightly in the idle, locked state, with little phosphorylation or PIP2 binding. However, this tight binding is loosened in growth states triggered by mechanical stimuli such as substrate stiffness, which may have relevance to fibrotic heart disease.
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Affiliation(s)
- Christopher Solís
- Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Brenda Russell
- Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL
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433
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Lee H, Eskin SG, Ono S, Zhu C, McIntire LV. Force-history dependence and cyclic mechanical reinforcement of actin filaments at the single molecular level. J Cell Sci 2019; 132:jcs.216911. [PMID: 30659118 DOI: 10.1242/jcs.216911] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 01/03/2019] [Indexed: 01/02/2023] Open
Abstract
The actin cytoskeleton is subjected to dynamic mechanical forces over time and the history of force loading may serve as mechanical preconditioning. While the actin cytoskeleton is known to be mechanosensitive, the mechanisms underlying force regulation of actin dynamics still need to be elucidated. Here, we investigated actin depolymerization under a range of dynamic tensile forces using atomic force microscopy. Mechanical loading by cyclic tensile forces induced significantly enhanced bond lifetimes and different force-loading histories resulted in different dissociation kinetics in G-actin-G-actin and G-actin-F-actin interactions. Actin subunits at the two ends of filaments formed bonds with distinct kinetics under dynamic force, with cyclic mechanical reinforcement more effective at the pointed end compared to that at the barbed end. Our data demonstrate force-history dependent reinforcement in actin-actin bonds and polarity of the actin depolymerization kinetics under cyclic tensile forces. These properties of actin may be important clues to understanding regulatory mechanisms underlying actin-dependent mechanotransduction and mechanosensitive cytoskeletal dynamics.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Hyunjung Lee
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Suzanne G Eskin
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Shoichiro Ono
- Departments of Pathology and Cell Biology, Emory University, Atlanta, GA 30322, USA .,Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Cheng Zhu
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA .,Geroge W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Larry V McIntire
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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434
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Tang LT, Diaz-Balzac CA, Rahman M, Ramirez-Suarez NJ, Salzberg Y, Lázaro-Peña MI, Bülow HE. TIAM-1/GEF can shape somatosensory dendrites independently of its GEF activity by regulating F-actin localization. eLife 2019; 8:38949. [PMID: 30694177 PMCID: PMC6370339 DOI: 10.7554/elife.38949] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 01/28/2019] [Indexed: 12/14/2022] Open
Abstract
Dendritic arbors are crucial for nervous system assembly, but the intracellular mechanisms that govern their assembly remain incompletely understood. Here, we show that the dendrites of PVD neurons in Caenorhabditis elegans are patterned by distinct pathways downstream of the DMA-1 leucine-rich transmembrane (LRR-TM) receptor. DMA-1/LRR-TM interacts through a PDZ ligand motif with the guanine nucleotide exchange factor TIAM-1/GEF in a complex with act-4/Actin to pattern higher order 4° dendrite branches by localizing F-actin to the distal ends of developing dendrites. Surprisingly, TIAM-1/GEF appears to function independently of Rac1 guanine nucleotide exchange factor activity. A partially redundant pathway, dependent on HPO-30/Claudin, regulates formation of 2° and 3° branches, possibly by regulating membrane localization and trafficking of DMA-1/LRR-TM. Collectively, our experiments suggest that HPO-30/Claudin localizes the DMA-1/LRR-TM receptor on PVD dendrites, which in turn can control dendrite patterning by directly modulating F-actin dynamics through TIAM-1/GEF.
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Affiliation(s)
- Leo Th Tang
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Carlos A Diaz-Balzac
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Maisha Rahman
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, United States
| | | | - Yehuda Salzberg
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Maria I Lázaro-Peña
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Hannes E Bülow
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
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435
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Torsional stress generated by ADF/cofilin on cross-linked actin filaments boosts their severing. Proc Natl Acad Sci U S A 2019; 116:2595-2602. [PMID: 30692249 PMCID: PMC6377502 DOI: 10.1073/pnas.1812053116] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Actin filaments assemble into ordered networks able to exert forces and shape cells. In response, filaments are exposed to mechanical stress which can potentially modulate their interactions with regulatory proteins. We developed in vitro tools to manipulate single filaments and study the impact of mechanics on the activity of actin depolymerizing factor (ADF)/cofilin, the central player in actin disassembly. While tension has almost no effect, curvature enhances severing by ADF/cofilin. We also discovered a mechanism that boosts the severing of anchored filaments: When binding to these filaments, ADF/cofilin locally increases their natural helicity, generating a torque that accelerates filament fragmentation up to 100-fold. As a consequence, interconnected filament networks are severed far more efficiently than independent filaments. Proteins of the actin depolymerizing factor (ADF)/cofilin family are the central regulators of actin filament disassembly. A key function of ADF/cofilin is to sever actin filaments. However, how it does so in a physiological context, where filaments are interconnected and under mechanical stress, remains unclear. Here, we monitor and quantify the action of ADF/cofilin in different mechanical situations by using single-molecule, single-filament, and filament network techniques, coupled to microfluidics. We find that local curvature favors severing, while tension surprisingly has no effect on cofilin binding and weakly enhances severing. Remarkably, we observe that filament segments that are held between two anchoring points, thereby constraining their twist, experience a mechanical torque upon cofilin binding. We find that this ADF/cofilin-induced torque does not hinder ADF/cofilin binding, but dramatically enhances severing. A simple model, which faithfully recapitulates our experimental observations, indicates that the ADF/cofilin-induced torque increases the severing rate constant 100-fold. A consequence of this mechanism, which we verify experimentally, is that cross-linked filament networks are severed by cofilin far more efficiently than nonconnected filaments. We propose that this mechanochemical mechanism is critical to boost ADF/cofilin’s ability to sever highly connected filament networks in cells.
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436
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From membrane receptors to protein synthesis and actin cytoskeleton: Mechanisms underlying long lasting forms of synaptic plasticity. Semin Cell Dev Biol 2019; 95:120-129. [PMID: 30634048 DOI: 10.1016/j.semcdb.2019.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 01/07/2019] [Accepted: 01/08/2019] [Indexed: 12/13/2022]
Abstract
Synaptic plasticity, the activity dependent change in synaptic strength, forms the molecular foundation of learning and memory. Synaptic plasticity includes structural changes, with spines changing their size to accomodate insertion and removal of postynaptic receptors, which are correlated with functional changes. Of particular relevance for memory storage are the long lasting forms of synaptic plasticity which are protein synthesis dependent. Due to the importance of spine structural plasticity and protein synthesis, this review focuses on the signaling pathways that connect synaptic stimulation with regulation of protein synthesis and remodeling of the actin cytoskeleton. We also review computational models that implement novel aspects of molecular signaling in synaptic plasticity, such as the role of neuromodulators and spatial microdomains, as well as highlight the need for computational models that connect activation of memory kinases with spine actin dynamics.
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437
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Cao J, Schnittler H. Putting VE-cadherin into JAIL for junction remodeling. J Cell Sci 2019; 132:132/1/jcs222893. [DOI: 10.1242/jcs.222893] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
ABSTRACT
Junction dynamics of endothelial cells are based on the integration of signal transduction, cytoskeletal remodeling and contraction, which are necessary for the formation and maintenance of monolayer integrity, but also enable repair and regeneration. The VE-cadherin–catenin complex forms the molecular basis of the adherence junctions and cooperates closely with actin filaments. Several groups have recently described small actin-driven protrusions at the cell junctions that are controlled by the Arp2/3 complex, contributing to cell junction regulation. We identified these protrusions as the driving force for VE-cadherin dynamics, as they directly induce new VE-cadherin-mediated adhesion sites, and have accordingly referred to these structures as junction-associated intermittent lamellipodia (JAIL). JAIL extend over only a few microns and thus provide the basis for a subcellular regulation of adhesion. The local (subcellular) VE-cadherin concentration and JAIL formation are directly interdependent, which enables autoregulation. Therefore, this mechanism can contribute a subcellularly regulated adaptation of cell contact dynamics, and is therefore of great importance for monolayer integrity and relative cell migration during wound healing and angiogenesis, as well as for inflammatory responses. In this Review, we discuss the mechanisms and functions underlying these actin-driven protrusions and consider their contribution to the dynamic regulation of endothelial cell junctions.
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Affiliation(s)
- Jiahui Cao
- Institute of Anatomy and Vascular Biology, Westfälische Wilhelms-Universität Münster, Münster Germany
| | - Hans Schnittler
- Institute of Anatomy and Vascular Biology, Westfälische Wilhelms-Universität Münster, Münster Germany
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438
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Varland S, Vandekerckhove J, Drazic A. Actin Post-translational Modifications: The Cinderella of Cytoskeletal Control. Trends Biochem Sci 2019; 44:502-516. [PMID: 30611609 DOI: 10.1016/j.tibs.2018.11.010] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 11/22/2018] [Accepted: 11/27/2018] [Indexed: 11/30/2022]
Abstract
Actin is one of the most abundant proteins in eukaryotic cells and the main component of the microfilament system. It plays essential roles in numerous cellular activities, including muscle contraction, maintenance of cell integrity, and motility, as well as transcriptional regulation. Besides interacting with various actin-binding proteins (ABPs), proper actin function is regulated by post-translational modifications (PTMs), such as acetylation, arginylation, oxidation, and others. Here, we explain how actin PTMs can contribute to filament formation and stability, and may have additional actin regulatory functions, which potentially contribute to disease development.
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Affiliation(s)
- Sylvia Varland
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5020 Bergen, Norway; Department of Biological Sciences, University of Bergen, Thormøhlensgate 53 A, N-5020 Bergen, Norway; Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Joël Vandekerckhove
- Department of Biochemistry, UGent Center for Medical Biotechnology, Ghent University, Albert Baertsoenkaai 3, 9000 Gent, Belgium
| | - Adrian Drazic
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5020 Bergen, Norway.
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439
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Zhang Y, Cao F, Zhou Y, Feng Z, Sit B, Krendel M, Yu CH. Tail domains of myosin-1e regulate phosphatidylinositol signaling and F-actin polymerization at the ventral layer of podosomes. Mol Biol Cell 2019; 30:622-635. [PMID: 30601698 PMCID: PMC6589698 DOI: 10.1091/mbc.e18-06-0398] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
During podosome formation, distinct phosphatidylinositol 3,4,5-trisphosphate lipid (PI(3,4,5)P3) production and F-actin polymerization take place at integrin-mediated adhesions. Membrane-associated actin regulation factors, such as myosin-1, serve as key molecules to link phosphatidylinositol signals to podosome assembly. Here, we report that long-tailed myosin-1e (Myo1e) is enriched at the ventral layer of the podosome core in a PI(3,4,5)P3-dependent manner. The combination of TH1 and TH2 (TH12) of Myo1e tail domains contains the essential motif for PI(3,4,5)P3-dependent membrane association and ventral localization at the podosome. TH12 KR2A (K772A and R782A) becomes dissociated from the plasma membrane. While F-actin polymerizations are initialized from the ventral layer of the podosome, TH12 precedes the recruitment of N-WASP and Arp2/3 in the initial phase of podosome formation. Overexpression of TH12, not TH12 KR2A, impedes PI(3,4,5)P3 signaling, restrains F-actin polymerization, and inhibits podosome formation. TH12 also suppresses gelatin degradation and migration speed of invadopodia-forming A375 melanoma cells. Thus, TH12 domain of Myo1e serves as a regulatory component to connect phosphatidylinositol signaling to F-actin polymerization at the podosome.
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Affiliation(s)
- Yage Zhang
- School of Biomedical Sciences, Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Fakun Cao
- School of Biomedical Sciences, Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Yuhuan Zhou
- School of Biomedical Sciences, Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Zhen Feng
- School of Biomedical Sciences, Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Brian Sit
- School of Biomedical Sciences, Faculty of Medicine, University of Hong Kong, Hong Kong.,Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London WC2R 2LS, United Kingdom
| | - Mira Krendel
- SUNY Upstate Medical University, Syracuse, NY 13210
| | - Cheng-Han Yu
- School of Biomedical Sciences, Faculty of Medicine, University of Hong Kong, Hong Kong
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440
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Bouillon R, Schuit F, Antonio L, Rastinejad F. Vitamin D Binding Protein: A Historic Overview. Front Endocrinol (Lausanne) 2019; 10:910. [PMID: 31998239 PMCID: PMC6965021 DOI: 10.3389/fendo.2019.00910] [Citation(s) in RCA: 160] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 12/13/2019] [Indexed: 02/06/2023] Open
Abstract
Vitamin D and all its metabolites are bound to a specific vitamin D binding protein, DBP. This protein was originally first discovered by its worldwide polymorphism and called Group-specific Component (GC). We now know that DBP and GC are the same protein and appeared early in the evolution of vertebrates. DBP is genetically the oldest member of the albuminoid family (including albumin, α-fetoprotein and afamin, all involved in transport of fatty acids or hormones). DBP has a single binding site for all vitamin D metabolites and has a high affinity for 25OHD and 1,25(OH)2D, thereby creating a large pool of circulating 25OHD, which prevents rapid vitamin D deficiency. DBP of higher vertebrates (not amphibians or reptiles) binds with very high affinity actin, thereby preventing the formation of polymeric actin fibrils in the circulation after tissue damage. Megalin is a cargo receptor and is together with cubilin needed to reabsorb DBP or the DBP-25OHD complex, thereby preventing the urinary loss of these proteins and 25OHD. The total concentrations of 25OHD and 1,25(OH)2D in DBP null mice or humans are extremely low but calcium and bone homeostasis remain normal. This is the strongest argument for claiming that the "free hormone hypothesis" also applies to the vitamin D hormone, 1,25(OH)2D. DBP also transports fatty acids, and can play a role in the immune system. DBP is genetically very polymorphic with three frequent alleles (DBP/GC 1f, 1s, and 2) but in total more than 120 different variants but its health consequences, if any, are not understood. A standardization of DBP assays is essential to further explore the role of DBP in physiology and diseases.
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Affiliation(s)
- Roger Bouillon
- Laboratory of Clinical and Experimental Endocrinology, Department of Chronic Diseases, Metabolism and Ageing, KU Leuven, Leuven, Belgium
- *Correspondence: Roger Bouillon
| | - Frans Schuit
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Leen Antonio
- Laboratory of Clinical and Experimental Endocrinology, Department of Chronic Diseases, Metabolism and Ageing, KU Leuven, Leuven, Belgium
- Department of Endocrinology, University Hospitals Leuven, Leuven, Belgium
| | - Fraydoon Rastinejad
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford, United Kingdom
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441
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Sun H, Luo Y, Miao Y. Purification of Globular Actin from Rabbit Muscle and Pyrene Fluorescent Assays to Investigate Actin Dynamics in vitro. Bio Protoc 2018; 8:e3102. [PMID: 34532548 DOI: 10.21769/bioprotoc.3102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 12/17/2017] [Accepted: 12/25/2017] [Indexed: 11/02/2022] Open
Abstract
Pyrene Fluorescent Assay is established to monitor the dynamic actin nucleation, elongation, capping and disassembly in vitro. This technique provides an easy handle procedure and straightforward visual data analysis. By coupling actin purification and polymerization assays in this protocol, the readers could quickly get the affordable and straightforward assays to study actin dynamics.
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Affiliation(s)
- He Sun
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Yuanyuan Luo
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore
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442
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Gegenfurtner FA, Zisis T, Al Danaf N, Schrimpf W, Kliesmete Z, Ziegenhain C, Enard W, Kazmaier U, Lamb DC, Vollmar AM, Zahler S. Transcriptional effects of actin-binding compounds: the cytoplasm sets the tone. Cell Mol Life Sci 2018; 75:4539-4555. [PMID: 30206640 PMCID: PMC11105542 DOI: 10.1007/s00018-018-2919-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/19/2018] [Accepted: 08/14/2018] [Indexed: 12/23/2022]
Abstract
Actin has emerged as a versatile regulator of gene transcription. Cytoplasmatic actin regulates mechanosensitive-signaling pathways such as MRTF-SRF and Hippo-YAP/TAZ. In the nucleus, both polymerized and monomeric actin directly interfere with transcription-associated molecular machineries. Natural actin-binding compounds are frequently used tools to study actin-related processes in cell biology. However, their influence on transcriptional regulation and intranuclear actin polymerization is poorly understood to date. Here, we analyze the effects of two representative actin-binding compounds, Miuraenamide A (polymerizing properties) and Latrunculin B (depolymerizing properties), on transcriptional regulation in primary cells. We find that actin stabilizing and destabilizing compounds inversely shift nuclear actin levels without a direct influence on polymerization state and intranuclear aspects of transcriptional regulation. Furthermore, we identify Miuraenamide A as a potent inducer of G-actin-dependent SRF target gene expression. In contrast, the F-actin-regulated Hippo-YAP/TAZ axis remains largely unaffected by compound-induced actin aggregation. This is due to the inability of AMOTp130 to bind to the amorphous actin aggregates resulting from treatment with miuraenamide. We conclude that actin-binding compounds predominantly regulate transcription via their influence on cytoplasmatic G-actin levels, while transcriptional processes relying on intranuclear actin polymerization or functional F-actin networks are not targeted by these compounds at tolerable doses.
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Affiliation(s)
- Florian A Gegenfurtner
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Themistoklis Zisis
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Nader Al Danaf
- Department of Chemistry, Munich Center for Integrated Protein Science, Nanosystems Initiative Munich and Centre for Nanoscience, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Waldemar Schrimpf
- Department of Chemistry, Munich Center for Integrated Protein Science, Nanosystems Initiative Munich and Centre for Nanoscience, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Zane Kliesmete
- Department Biology II, Anthropology and Human Genomics, Ludwig-Maximilians-University Munich, 82152, Martinsried, Germany
| | - Christoph Ziegenhain
- Department Biology II, Anthropology and Human Genomics, Ludwig-Maximilians-University Munich, 82152, Martinsried, Germany
| | - Wolfgang Enard
- Department Biology II, Anthropology and Human Genomics, Ludwig-Maximilians-University Munich, 82152, Martinsried, Germany
| | - Uli Kazmaier
- Institute of Organic Chemistry, Saarland University, 66041, Saarbrücken, Germany
| | - Don C Lamb
- Department of Chemistry, Munich Center for Integrated Protein Science, Nanosystems Initiative Munich and Centre for Nanoscience, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Angelika M Vollmar
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Stefan Zahler
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-University Munich, 81377, Munich, Germany.
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443
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Kelpsch DJ, Tootle TL. Nuclear Actin: From Discovery to Function. Anat Rec (Hoboken) 2018; 301:1999-2013. [PMID: 30312531 PMCID: PMC6289869 DOI: 10.1002/ar.23959] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 04/20/2018] [Accepted: 05/14/2018] [Indexed: 01/02/2023]
Abstract
While actin was discovered in the nucleus over 50 years ago, research lagged for decades due to strong skepticism. The revitalization of research into nuclear actin occurred after it was found that cellular stresses induce the nuclear localization and alter the structure of actin. These studies provided the first hints that actin has a nuclear function. Subsequently, it was established that the nuclear import and export of actin is highly regulated. While the structures of nuclear actin remain unclear, it can function as monomers, polymers, and even rods. Furthermore, even within a given structure, distinct pools of nuclear actin that can be differentially labeled have been identified. Numerous mechanistic studies have uncovered an array of functions for nuclear actin. It regulates the activity of RNA polymerases, as well as specific transcription factors. Actin also modulates the activity of several chromatin remodeling complexes and histone deacetylases, to ultimately impinge on transcriptional programing and DNA damage repair. Further, nuclear actin mediates chromatin movement and organization. It has roles in meiosis and mitosis, and these functions may be functionally conserved from ancient bacterial actin homologs. The structure and integrity of the nuclear envelope and sub-nuclear compartments are also regulated by nuclear actin. Furthermore, nuclear actin contributes to human diseases like cancer, neurodegeneration, and myopathies. Here, we explore the early discovery of actin in the nucleus and discuss the forms and functions of nuclear actin in both normal and disease contexts. Anat Rec, 301:1999-2013, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Daniel J. Kelpsch
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, 51 Newton Rd, 1-500 BSB, Iowa City, IA 52242
| | - Tina L. Tootle
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, 51 Newton Rd, 1-500 BSB, Iowa City, IA 52242
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444
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Rodriguez A, Kashina A. Posttranscriptional and Posttranslational Regulation of Actin. Anat Rec (Hoboken) 2018; 301:1991-1998. [PMID: 30312009 DOI: 10.1002/ar.23958] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 04/12/2018] [Accepted: 04/14/2018] [Indexed: 12/14/2022]
Abstract
Actin is one of the most abundant intracellular proteins, essential in every eukaryotic cell type. Actin plays key roles in tissue morphogenesis, cell adhesion, muscle contraction, and developmental reprogramming. Most actin studies have focused on its regulation at the protein level, either directly or through differential interactions with over a hundred intracellular binding partners. However, numerous studies emerging in recent years demonstrate specific types of nucleotide-level regulation that strongly affect non-muscle actins during cell migration and adhesion and are potentially applicable to other members of the actin family. This regulation involves zipcode-mediated actin mRNA targeting to the cell periphery, proposed to mediate local synthesis of actin at the cell leading edge, as well as the recently discovered N-terminal arginylation that specifically targets non-muscle β-actin via a nucleotide-dependent mechanism. Moreover, a study published this year suggests that actin's essential roles at the organismal level may be entirely nucleotide-dependent. This review summarizes the emerging data on actin's nucleotide-level regulation. Anat Rec, 301:1991-1998, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Alexis Rodriguez
- Department of Biological Sciences, Rutgers University, Newark, New Jersey
| | - Anna Kashina
- Department of Biomedical Sciences, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, Pennsylvania
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445
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Pfajfer L, Mair NK, Jiménez-Heredia R, Genel F, Gulez N, Ardeniz Ö, Hoeger B, Bal SK, Madritsch C, Kalinichenko A, Chandra Ardy R, Gerçeker B, Rey-Barroso J, Ijspeert H, Tangye SG, Simonitsch-Klupp I, Huppa JB, van der Burg M, Dupré L, Boztug K. Mutations affecting the actin regulator WD repeat–containing protein 1 lead to aberrant lymphoid immunity. J Allergy Clin Immunol 2018; 142:1589-1604.e11. [DOI: 10.1016/j.jaci.2018.04.023] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 03/12/2018] [Accepted: 04/06/2018] [Indexed: 11/28/2022]
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446
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Aksnes H, Marie M, Arnesen T, Drazic A. Actin polymerization and cell motility are affected by NAA80-mediated posttranslational N-terminal acetylation of actin. Commun Integr Biol 2018; 11:e1526572. [PMID: 30534344 PMCID: PMC6284563 DOI: 10.1080/19420889.2018.1526572] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/01/2018] [Accepted: 09/08/2018] [Indexed: 10/30/2022] Open
Abstract
Actin is the most abundant protein in our cells, and also one of the most studied. Nevertheless, an important modifier of actin, the N-terminal acetyltransferase (NAT) for actin, remained unknown until now. The recent identification of the enzyme that catalyzes actin acetylation, has opened up for functional studies of unacetylated actin using knockout cells. This enzyme, called NAA80 (Nα-acetyltransferase 80) or NatH, belongs to the NAT family of enzymes, which together provides N-terminal acetylation for around 80 % of the human proteome. In many cases, N-terminal acetylation is essential. In the case of actin, the acetyl group that NAA80 attaches to actin plays an important role in actin's polymerization properties as well as in actin's function in cell migration.
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Affiliation(s)
| | - Michael Marie
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Thomas Arnesen
- Department of Biomedicine, University of Bergen, Bergen, Norway.,Department of Biological Sciences, University of Bergen, Bergen, Norway.,Department of Surgery, Haukeland University Hospital, Bergen, Norway
| | - Adrian Drazic
- Department of Biomedicine, University of Bergen, Bergen, Norway
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447
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Abstract
The pulmonary endothelial cell forms a critical semi-permeable barrier between the vascular and interstitial space. As part of the blood-gas barrier in the lung, the endothelium plays a key role in normal physiologic function and pathologic disease. Changes in endothelial cell shape, defined by its plasma membrane, determine barrier integrity. A number of key cytoskeletal regulatory and effector proteins including non-muscle myosin light chain kinase, cortactin, and Arp 2/3 mediate actin rearrangements to form cortical and membrane associated structures in response to barrier enhancing stimuli. These actin formations support and interact with junctional complexes and exert forces to protrude the lipid membrane to and close gaps between individual cells. The current knowledge of these cytoskeletal processes and regulatory proteins are the subject of this review. In addition, we explore novel advancements in cellular imaging that are poised to shed light on the complex nature of pulmonary endothelial permeability.
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448
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Iwamoto DV, Huehn A, Simon B, Huet-Calderwood C, Baldassarre M, Sindelar CV, Calderwood DA. Structural basis of the filamin A actin-binding domain interaction with F-actin. Nat Struct Mol Biol 2018; 25:918-927. [PMID: 30224736 PMCID: PMC6173970 DOI: 10.1038/s41594-018-0128-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 08/03/2018] [Indexed: 11/23/2022]
Abstract
Actin-cross-linking proteins assemble actin filaments into higher-order structures essential for orchestrating cell shape, adhesion, and motility. Missense mutations in the tandem calponin homology domains of their actin-binding domains (ABDs) underlie numerous genetic diseases, but a molecular understanding of these pathologies is hampered by the lack of high-resolution structures of any actin-cross-linking protein bound to F-actin. Here, taking advantage of a high-affinity, disease-associated mutant of the human filamin A (FLNa) ABD, we combine cryo-electron microscopy and functional studies to reveal at near-atomic resolution how the first calponin homology domain (CH1) and residues immediately N-terminal to it engage actin. We further show that reorientation of CH2 relative to CH1 is required to avoid clashes with actin and to expose F-actin-binding residues on CH1. Our data explain localization of disease-associated loss-of-function mutations to FLNaCH1 and gain-of-function mutations to the regulatory FLNaCH2. Sequence conservation argues that this provides a general model for ABD-F-actin binding.
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Affiliation(s)
| | - Andrew Huehn
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Bertrand Simon
- Department of Pharmacology, Yale University, New Haven, CT, USA
| | | | - Massimiliano Baldassarre
- Department of Pharmacology, Yale University, New Haven, CT, USA
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, UK
| | - Charles V Sindelar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.
| | - David A Calderwood
- Department of Pharmacology, Yale University, New Haven, CT, USA.
- Department of Cell Biology, Yale University, New Haven, CT, USA.
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449
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Kulkarni SS, Griffin JN, Date PP, Liem KF, Khokha MK. WDR5 Stabilizes Actin Architecture to Promote Multiciliated Cell Formation. Dev Cell 2018; 46:595-610.e3. [PMID: 30205038 PMCID: PMC6177229 DOI: 10.1016/j.devcel.2018.08.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 06/18/2018] [Accepted: 08/11/2018] [Indexed: 12/16/2022]
Abstract
The actin cytoskeleton is critical to shape cells and pattern intracellular organelles, which collectively drives tissue morphogenesis. In multiciliated cells (MCCs), apical actin drives expansion of the cell surface necessary to host hundreds of cilia. The apical actin also forms a lattice to uniformly distribute basal bodies. This apical actin network is dynamically remodeled, but the molecules that regulate its architecture remain poorly understood. We identify the chromatin modifier, WDR5, as a regulator of apical F-actin in MCCs. Unexpectedly in MCCs, WDR5 has a function independent of chromatin modification. We discover a scaffolding role for WDR5 between the basal body and F-actin. Specifically, WDR5 binds to basal bodies and migrates apically, where F-actin organizes around WDR5. Using a monomer trap for G-actin, we show that WDR5 stabilizes F-actin to maintain lattice architecture. In summary, we identify a non-chromatin role for WDR5 in stabilizing F-actin in MCCs.
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Affiliation(s)
- Saurabh S Kulkarni
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - John N Griffin
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Priya P Date
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Karel F Liem
- Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Mustafa K Khokha
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
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450
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Douglas RG, Nandekar P, Aktories JE, Kumar H, Weber R, Sattler JM, Singer M, Lepper S, Sadiq SK, Wade RC, Frischknecht F. Inter-subunit interactions drive divergent dynamics in mammalian and Plasmodium actin filaments. PLoS Biol 2018; 16:e2005345. [PMID: 30011270 PMCID: PMC6055528 DOI: 10.1371/journal.pbio.2005345] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 06/13/2018] [Indexed: 01/01/2023] Open
Abstract
Cell motility is essential for protozoan and metazoan organisms and typically relies on the dynamic turnover of actin filaments. In metazoans, monomeric actin polymerises into usually long and stable filaments, while some protozoans form only short and highly dynamic actin filaments. These different dynamics are partly due to the different sets of actin regulatory proteins and partly due to the sequence of actin itself. Here we probe the interactions of actin subunits within divergent actin filaments using a comparative dynamic molecular model and explore their functions using Plasmodium, the protozoan causing malaria, and mouse melanoma derived B16-F1 cells as model systems. Parasite actin tagged to a fluorescent protein (FP) did not incorporate into mammalian actin filaments, and rabbit actin-FP did not incorporate into parasite actin filaments. However, exchanging the most divergent region of actin subdomain 3 allowed such reciprocal incorporation. The exchange of a single amino acid residue in subdomain 2 (N41H) of Plasmodium actin markedly improved incorporation into mammalian filaments. In the parasite, modification of most subunit–subunit interaction sites was lethal, whereas changes in actin subdomains 1 and 4 reduced efficient parasite motility and hence mosquito organ penetration. The strong penetration defects could be rescued by overexpression of the actin filament regulator coronin. Through these comparative approaches we identified an essential and common contributor, subdomain 3, which drives the differential dynamic behaviour of two highly divergent eukaryotic actins in motile cells. Actin is one of the most abundant and conserved proteins across eukaryotes. Its ability to assemble from individual monomers into dynamic polymers is essential for many cellular functions, including division and motility. In most cells, actin is able to form long and stable filaments. However, an actin of the malaria-causing parasite Plasmodium, while having a very similar monomer structure to actins from other eukaryotes, forms only short and unstable filaments. These short and dynamic filaments are crucial in allowing the parasite to move very rapidly in tissue. Here we investigated the basis of these differences. We used molecular dynamics simulations of actin filaments to investigate the actin–actin interfaces in filaments from Plasmodium and rabbit. We next engineered parasites to express chimeric actins that contained different parts of rabbit and parasite actin and thereby identified actin residues important for parasite viability and progression across the life cycle. We could rescue the most prominent defect specifically with overexpression of the actin binding protein coronin. This suggests that the more stable actin harms the parasite and that coronin helps in recycling filaments. By screening the effects of actin chimeras in mammalian cells, we also identified regions that allow these different actins to efficiently interact with each other. Taken together, our results improve our understanding of the interactions required for actin to incorporate into filaments across divergent eukaryotes.
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Affiliation(s)
- Ross G. Douglas
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Prajwal Nandekar
- Molecular and Cellular Modeling, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
- Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Julia-Elisabeth Aktories
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Hirdesh Kumar
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
- Molecular and Cellular Modeling, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
| | - Rebekka Weber
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Julia M. Sattler
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Mirko Singer
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Simone Lepper
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - S. Kashif Sadiq
- Molecular and Cellular Modeling, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
| | - Rebecca C. Wade
- Molecular and Cellular Modeling, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
- Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg, Germany
- * E-mail: (FF); (RCW)
| | - Friedrich Frischknecht
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
- * E-mail: (FF); (RCW)
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