51
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Glyakina AV, Surin AK, Grishin SY, Selivanova OM, Suvorina MY, Bobyleva LG, Vikhlyantsev IM, Galzitskaya OV. New Model for Stacking Monomers in Filamentous Actin from Skeletal Muscles of Oryctolagus cuniculus. Int J Mol Sci 2020; 21:ijms21218319. [PMID: 33171915 PMCID: PMC7664232 DOI: 10.3390/ijms21218319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/23/2020] [Accepted: 11/03/2020] [Indexed: 12/27/2022] Open
Abstract
To date, some scientific evidence (limited proteolysis, mass spectrometry analysis, electron microscopy (EM)) has accumulated, which indicates that the generally accepted model of double-stranded of filamentous actin (F-actin) organization in eukaryotic cells is not the only one. This entails an ambiguous understanding of many of the key cellular processes in which F-actin is involved. For a detailed understanding of the mechanism of F-actin assembly and actin interaction with its partners, it is necessary to take into account the polymorphism of the structural organization of F-actin at the molecular level. Using electron microscopy, limited proteolysis, mass spectrometry, X-ray diffraction, and structural modeling we demonstrated that F-actin presented in the EM images has no double-stranded organization, the regions of protease resistance are accessible for action of proteases in F-actin models. Based on all data, a new spatial model of filamentous actin is proposed, and the F-actin polymorphism is discussed.
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Affiliation(s)
- Anna V. Glyakina
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (A.V.G.); (A.K.S.); (S.Y.G.); (O.M.S.); (M.Y.S.)
- Institute of Mathematical Problems of Biology, Russian Academy of Sciences, Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
| | - Alexey K. Surin
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (A.V.G.); (A.K.S.); (S.Y.G.); (O.M.S.); (M.Y.S.)
- The Branch of the Institute of Bioorganic Chemistry, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
- State Research Center for Applied Microbiology and Biotechnology, 142279 Obolensk, Moscow Region, Russia
| | - Sergei Yu. Grishin
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (A.V.G.); (A.K.S.); (S.Y.G.); (O.M.S.); (M.Y.S.)
| | - Olga M. Selivanova
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (A.V.G.); (A.K.S.); (S.Y.G.); (O.M.S.); (M.Y.S.)
| | - Mariya Yu. Suvorina
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (A.V.G.); (A.K.S.); (S.Y.G.); (O.M.S.); (M.Y.S.)
| | - Liya G. Bobyleva
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (L.G.B.); (I.M.V.)
| | - Ivan M. Vikhlyantsev
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (L.G.B.); (I.M.V.)
| | - Oxana V. Galzitskaya
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (A.V.G.); (A.K.S.); (S.Y.G.); (O.M.S.); (M.Y.S.)
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (L.G.B.); (I.M.V.)
- Correspondence: ; Tel.: +7-903-675-0156
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52
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Pathak S, Parkar H, Tripathi S, Kale A. Ofloxacin as a Disruptor of Actin Aggresome "Hirano Bodies": A Potential Repurposed Drug for the Treatment of Neurodegenerative Diseases. Front Aging Neurosci 2020; 12:591579. [PMID: 33132905 PMCID: PMC7573105 DOI: 10.3389/fnagi.2020.591579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 09/09/2020] [Indexed: 01/27/2023] Open
Abstract
There is a growing number of aging populations that are more prone to the prevalence of neuropathological disorders. Two major diseases that show a late onset of the symptoms include Alzheimer’s disorder (AD) and Parkinson’s disorder (PD), which are causing an unexpected social and economic impact on the families. A large number of researches in the last decade have focused upon the role of amyloid precursor protein, Aβ-plaque, and intraneuronal neurofibrillary tangles (tau-proteins). However, there is very few understanding of actin-associated paracrystalline structures formed in the hippocampus region of the brain and are called Hirano bodies. These actin-rich inclusion bodies are known to modulate the synaptic plasticity and employ conspicuous effects on long-term potentiation and paired-pulse paradigms. Since the currently known drugs have very little effect in controlling the progression of these diseases, there is a need to develop therapeutic agents, which can have improved efficacy and bioavailability, and can transport across the blood–brain barrier. Moreover, finding novel targets involving compound screening is both laborious and is an expensive process in itself followed by equally tedious Food and Drug Administration (FDA) approval exercise. Finding alternative functions to the already existing FDA-approved molecules for reversing the progression of age-related proteinopathies is of utmost importance. In the current study, we decipher the role of a broad-spectrum general antibiotic (Ofloxacin) on actin polymerization dynamics using various biophysical techniques like right-angle light scattering, dynamic light scattering, circular dichroism spectrometry, isothermal titration calorimetry, scanning electron microscopy, etc. We have also performed in silico docking studies to deduce a plausible mechanism of the drug binding to the actin. We report that actin gets disrupted upon binding to Ofloxacin in a concentration-dependent manner. We have inferred that Ofloxacin, when attached to a drug delivery system, can act as a good candidate for the treatment of neuropathological diseases.
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Affiliation(s)
- Samridhi Pathak
- School of Chemical Sciences, University of Mumbai - Department of Atomic Energy Center for Excellence in Basic Sciences, University of Mumbai, Vidyanagari Campus, Mumbai, India
| | - Haifa Parkar
- School of Chemical Sciences, University of Mumbai - Department of Atomic Energy Center for Excellence in Basic Sciences, University of Mumbai, Vidyanagari Campus, Mumbai, India
| | - Sarita Tripathi
- School of Chemical Sciences, University of Mumbai - Department of Atomic Energy Center for Excellence in Basic Sciences, University of Mumbai, Vidyanagari Campus, Mumbai, India
| | - Avinash Kale
- School of Chemical Sciences, University of Mumbai - Department of Atomic Energy Center for Excellence in Basic Sciences, University of Mumbai, Vidyanagari Campus, Mumbai, India
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53
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Predictive assembling model reveals the self-adaptive elastic properties of lamellipodial actin networks for cell migration. Commun Biol 2020; 3:616. [PMID: 33106551 PMCID: PMC7588425 DOI: 10.1038/s42003-020-01335-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 09/30/2020] [Indexed: 12/14/2022] Open
Abstract
Branched actin network supports cell migration through extracellular microenvironments. However, it is unknown how intracellular proteins adapt the elastic properties of the network to the highly varying extracellular resistance. Here we develop a three-dimensional assembling model to simulate the realistic self-assembling process of the network by encompassing intracellular proteins and their dynamic interactions. Combining this multiscale model with finite element method, we reveal that the network can not only sense the variation of extracellular resistance but also self-adapt its elastic properties through remodeling with intracellular proteins. Such resistance-adaptive elastic behaviours are versatile and essential in supporting cell migration through varying extracellular microenvironments. The bending deformation mechanism and anisotropic Poisson's ratios determine why lamellipodia persistently evolve into sheet-like structures. Our predictions are confirmed by published experiments. The revealed self-adaptive elastic properties of the networks are also applicable to the endocytosis, phagocytosis, vesicle trafficking, intracellular pathogen transport and dendritic spine formation.
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54
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Rust MB, Khudayberdiev S, Pelucchi S, Marcello E. CAPt'n of Actin Dynamics: Recent Advances in the Molecular, Developmental and Physiological Functions of Cyclase-Associated Protein (CAP). Front Cell Dev Biol 2020; 8:586631. [PMID: 33072768 PMCID: PMC7543520 DOI: 10.3389/fcell.2020.586631] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 08/26/2020] [Indexed: 12/11/2022] Open
Abstract
Cyclase-associated protein (CAP) has been discovered three decades ago in budding yeast as a protein that associates with the cyclic adenosine monophosphate (cAMP)-producing adenylyl cyclase and that suppresses a hyperactive RAS2 variant. Since that time, CAP has been identified in all eukaryotic species examined and it became evident that the activity in RAS-cAMP signaling is restricted to a limited number of species. Instead, its actin binding activity is conserved among eukaryotes and actin cytoskeleton regulation emerged as its primary function. However, for many years, the molecular functions as well as the developmental and physiological relevance of CAP remained unknown. In the present article, we will compile important recent progress on its molecular functions that identified CAP as a novel key regulator of actin dynamics, i.e., the spatiotemporally controlled assembly and disassembly of actin filaments (F-actin). These studies unraveled a cooperation with ADF/Cofilin and Twinfilin in F-actin disassembly, a nucleotide exchange activity on globular actin monomers (G-actin) that is required for F-actin assembly and an inhibitory function towards the F-actin assembly factor INF2. Moreover, by focusing on selected model organisms, we will review current literature on its developmental and physiological functions, and we will present studies implicating CAP in human pathologies. Together, this review article summarizes and discusses recent achievements in understanding the molecular, developmental and physiological functions of CAP, which led this protein emerge as a novel CAPt'n of actin dynamics.
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Affiliation(s)
- Marco B Rust
- Molecular Neurobiology Group, Institute of Physiological Chemistry, University of Marburg, Marburg, Germany.,DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, University of Marburg, Marburg, Germany.,Center for Mind, Brain and Behavior, University of Marburg and Justus-Liebig-University Giessen, Giessen, Germany
| | - Sharof Khudayberdiev
- Molecular Neurobiology Group, Institute of Physiological Chemistry, University of Marburg, Marburg, Germany
| | - Silvia Pelucchi
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Elena Marcello
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
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Cheng Y, Felix B, Othmer HG. The Roles of Signaling in Cytoskeletal Changes, Random Movement, Direction-Sensing and Polarization of Eukaryotic Cells. Cells 2020; 9:E1437. [PMID: 32531876 PMCID: PMC7348768 DOI: 10.3390/cells9061437] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/28/2020] [Accepted: 05/29/2020] [Indexed: 12/21/2022] Open
Abstract
Movement of cells and tissues is essential at various stages during the lifetime of an organism, including morphogenesis in early development, in the immune response to pathogens, and during wound-healing and tissue regeneration. Individual cells are able to move in a variety of microenvironments (MEs) (A glossary of the acronyms used herein is given at the end) by suitably adapting both their shape and how they transmit force to the ME, but how cells translate environmental signals into the forces that shape them and enable them to move is poorly understood. While many of the networks involved in signal detection, transduction and movement have been characterized, how intracellular signals control re-building of the cyctoskeleton to enable movement is not understood. In this review we discuss recent advances in our understanding of signal transduction networks related to direction-sensing and movement, and some of the problems that remain to be solved.
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Affiliation(s)
- Yougan Cheng
- Bristol Myers Squibb, Route 206 & Province Line Road, Princeton, NJ 08543, USA;
| | - Bryan Felix
- School of Mathematics, University of Minnesota, Minneapolis, MN 55445, USA;
| | - Hans G. Othmer
- School of Mathematics, University of Minnesota, Minneapolis, MN 55445, USA;
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56
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Gallop J. Filopodia and their links with membrane traffic and cell adhesion. Semin Cell Dev Biol 2020; 102:81-89. [DOI: 10.1016/j.semcdb.2019.11.017] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 11/14/2019] [Accepted: 11/28/2019] [Indexed: 01/24/2023]
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57
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Malek N, Mrówczyńska E, Michrowska A, Mazurkiewicz E, Pavlyk I, Mazur AJ. Knockout of ACTB and ACTG1 with CRISPR/Cas9(D10A) Technique Shows that Non-Muscle β and γ Actin Are Not Equal in Relation to Human Melanoma Cells' Motility and Focal Adhesion Formation. Int J Mol Sci 2020; 21:ijms21082746. [PMID: 32326615 PMCID: PMC7216121 DOI: 10.3390/ijms21082746] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/10/2020] [Accepted: 04/10/2020] [Indexed: 12/12/2022] Open
Abstract
Non-muscle actins have been studied for many decades; however, the reason for the existence of both isoforms is still unclear. Here we show, for the first time, a successful inactivation of the ACTB (CRISPR clones with inactivated ACTB, CR-ACTB) and ACTG1 (CRISPR clones with inactivated ACTG1, CR-ACTG1) genes in human melanoma cells (A375) via the RNA-guided D10A mutated Cas9 nuclease gene editing [CRISPR/Cas9(D10A)] technique. This approach allowed us to evaluate how melanoma cell motility was impacted by the lack of either β actin coded by ACTB or γ actin coded by ACTG1. First, we observed different distributions of β and γ actin in the cells, and the absence of one actin isoform was compensated for via increased expression of the other isoform. Moreover, we noted that γ actin knockout had more severe consequences on cell migration and invasion than β actin knockout. Next, we observed that the formation rate of bundled stress fibers in CR-ACTG1 cells was increased, but lamellipodial activity in these cells was impaired, compared to controls. Finally, we discovered that the formation rate of focal adhesions (FAs) and, subsequently, FA-dependent signaling were altered in both the CR-ACTB and CR-ACTG1 clones; however, a more detrimental effect was observed for γ actin-deficient cells. Our research shows that both non-muscle actins play distinctive roles in melanoma cells’ FA formation and motility.
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58
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Bleicher P, Sciortino A, Bausch AR. The dynamics of actin network turnover is self-organized by a growth-depletion feedback. Sci Rep 2020; 10:6215. [PMID: 32277095 PMCID: PMC7148320 DOI: 10.1038/s41598-020-62942-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 02/24/2020] [Indexed: 01/22/2023] Open
Abstract
The dynamics of actin networks is modulated by a machinery consisting of actin binding proteins that control the turnover of filaments in space and time. To study this complex orchestration, in vitro reconstitution approaches strive to project actin dynamics in ideal, minimal systems. To this extent we reconstitute a self-supplying, dense network of globally treadmilling filaments. In this system we analyze growth and intrinsic turnover by means of FRAP measurements and thereby demonstrate how the depletion of monomers and actin binding partners modulate the dynamics in active actin networks. The described effects occur only in dense networks, as single filament dynamics are unable to produce depletion effects to this extent. Furthermore, we demonstrate a synergistic relationship between the nucleators formin and Arp2/3 when branched networks and formin-induced networks are colocalized. As a result, the formin-enhanced filament turnover depletes cofilin at the surface and thus protects the dense, Arp2/3 polymerized network from debranching. Ultimately, these results may be key for understanding the maintenance of the two contradicting requirements of network stability and dynamics in cells.
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Affiliation(s)
- P Bleicher
- Lehrstuhl für Biophysik E27, Physik-Department, Technische Universität München, Garching, Germany
| | - A Sciortino
- Lehrstuhl für Biophysik E27, Physik-Department, Technische Universität München, Garching, Germany
| | - A R Bausch
- Lehrstuhl für Biophysik E27, Physik-Department, Technische Universität München, Garching, Germany.
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59
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Dalaka E, Kronenberg NM, Liehm P, Segall JE, Prystowsky MB, Gather MC. Direct measurement of vertical forces shows correlation between mechanical activity and proteolytic ability of invadopodia. SCIENCE ADVANCES 2020; 6:eaax6912. [PMID: 32195338 PMCID: PMC7065877 DOI: 10.1126/sciadv.aax6912] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 12/17/2019] [Indexed: 05/03/2023]
Abstract
Mechanobiology plays a prominent role in cancer invasion and metastasis. The ability of a cancer to degrade extracellular matrix (ECM) is likely connected to its invasiveness. Many cancer cells form invadopodia-micrometer-sized cellular protrusions that promote invasion through matrix degradation (proteolysis). Although it has been hypothesized that invadopodia exert mechanical force that is implicated in cancer invasion, direct measurements remain elusive. Here, we use a recently developed interferometric force imaging technique that provides piconewton resolution to quantify invadopodial forces in cells of head and neck squamous carcinoma and to monitor their temporal dynamics. We compare the force exerted by individual protrusions to their ability to degrade ECM and investigate the mechanical effects of inhibiting invadopodia through overexpression of microRNA-375. By connecting the biophysical and biochemical characteristics of invadopodia, our study provides a new perspective on cancer invasion that, in the future, may help to identify biomechanical targets for cancer therapy.
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Affiliation(s)
- E. Dalaka
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - N. M. Kronenberg
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - P. Liehm
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - J. E. Segall
- Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | | | - M. C. Gather
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
- Corresponding author.
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60
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Bugyi B, Kellermayer M. The discovery of actin: "to see what everyone else has seen, and to think what nobody has thought". J Muscle Res Cell Motil 2020; 41:3-9. [PMID: 31093826 PMCID: PMC7109165 DOI: 10.1007/s10974-019-09515-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 05/03/2019] [Indexed: 12/12/2022]
Abstract
Actin is among the most highly abundant and ubiquitous proteins in eukaryotic cells. The structure, dynamics and functional diversity of actin have continued to mesmerise cell and molecular biologists, biophysicists and physiologists for more than three quarters of a century. The discovery and initial characterization of actin, which took place in the laboratory of Albert Szent-Györgyi by Ilona Banga and Brúnó F. Straub during the second world war in Hungary, is a remarkable and inspiring moment in the history of science. Many of the early thoughts and ideas on the properties and functions of actin and particularly actomyosin, which are referred to in this short historical overview, resonate freshly even today.
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Affiliation(s)
- Beáta Bugyi
- Department of Biophysics, Medical School, University of Pécs, Szigeti str. 12, Pécs, 7624, Hungary.
| | - Miklós Kellermayer
- Department of Biophysics and Radiation Biology, Faculty of Medicine, Semmelweis University, Tűzoltó str. 37-47, Budapest, IX, 1428, Hungary.
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61
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Abstract
Supramolecular polymers are non-covalent assemblies of unimeric building blocks connected by secondary interactions and hold great promises due to their dynamic nature.
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Affiliation(s)
| | | | - Sebastien Perrier
- Department of Chemistry
- University of Warwick
- Coventry CV4 7AL
- UK
- Faculty of Pharmacy and Pharmaceutical Sciences
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62
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Antoine M, Patrick KL, Soret J, Duc P, Rage F, Cacciottolo R, Nissen KE, Cauchi RJ, Krogan NJ, Guthrie C, Gachet Y, Bordonné R. Splicing Defects of the Profilin Gene Alter Actin Dynamics in an S. pombe SMN Mutant. iScience 2019; 23:100809. [PMID: 31927482 PMCID: PMC6957872 DOI: 10.1016/j.isci.2019.100809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 09/13/2019] [Accepted: 12/23/2019] [Indexed: 12/18/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating motor neuron disorder caused by mutations in the survival motor neuron (SMN) gene. It remains unclear how SMN deficiency leads to the loss of motor neurons. By screening Schizosaccharomyces pombe, we found that the growth defect of an SMN mutant can be alleviated by deletion of the actin-capping protein subunit gene acp1+. We show that SMN mutated cells have splicing defects in the profilin gene, which thus directly hinder actin cytoskeleton homeostasis including endocytosis and cytokinesis. We conclude that deletion of acp1+ in an SMN mutant background compensates for actin cytoskeleton alterations by restoring redistribution of actin monomers between different types of cellular actin networks. Our data reveal a direct correlation between an impaired function of SMN in snRNP assembly and defects in actin dynamics. They also point to important common features in the pathogenic mechanism of SMA and ALS. Splicing defects in the profilin gene in an S. pombe SMN mutant SMN mutant contains excessively polymerized actin Altered actin dynamics in the SMN mutant hinders endocytosis and cytokinesis Deletion of the acp1 subunit restores actin dynamics in the SMN mutant
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Affiliation(s)
- Marie Antoine
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | | | - Johann Soret
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Pauline Duc
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Florence Rage
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Rebecca Cacciottolo
- Department of Physiology and Biochemistry, University of Malta, Msida, Malta
| | | | - Ruben J Cauchi
- Department of Physiology and Biochemistry, University of Malta, Msida, Malta
| | | | | | - Yannick Gachet
- Centre de Biologie Integrative, University of Toulouse, CNRS, Toulouse, France
| | - Rémy Bordonné
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France.
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63
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The Cytoskeleton as Regulator of Cell Signaling Pathways. Trends Biochem Sci 2019; 45:96-107. [PMID: 31812462 DOI: 10.1016/j.tibs.2019.11.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 11/04/2019] [Accepted: 11/07/2019] [Indexed: 02/06/2023]
Abstract
During interphase, filamentous actin, microtubules, and intermediate filaments regulate cell shape, motility, transport, and interactions with the environment. These activities rely on signaling events that control cytoskeleton properties. Recent studies uncovered mechanisms that go far beyond this one-directional flow of information. Thus, the three branches of the cytoskeleton impinge on signaling pathways to determine their activities. We propose that this regulatory role of the cytoskeleton provides sophisticated mechanisms to control the spatiotemporal output and the intensity of signaling events. Specific examples emphasize these emerging contributions of the cytoskeleton to cell physiology. In our opinion, further exploration of these pathways will uncover new concepts of cellular communication that originate from the cytoskeleton.
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64
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Shekhar S, Chung J, Kondev J, Gelles J, Goode BL. Synergy between Cyclase-associated protein and Cofilin accelerates actin filament depolymerization by two orders of magnitude. Nat Commun 2019; 10:5319. [PMID: 31757952 PMCID: PMC6876572 DOI: 10.1038/s41467-019-13268-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 10/29/2019] [Indexed: 11/29/2022] Open
Abstract
Cellular actin networks can be rapidly disassembled and remodeled in a few seconds, yet in vitro actin filaments depolymerize slowly over minutes. The cellular mechanisms enabling actin to depolymerize this fast have so far remained obscure. Using microfluidics-assisted TIRF, we show that Cyclase-associated protein (CAP) and Cofilin synergize to processively depolymerize actin filament pointed ends at a rate 330-fold faster than spontaneous depolymerization. Single molecule imaging further reveals that hexameric CAP molecules interact with the pointed ends of Cofilin-decorated filaments for several seconds at a time, removing approximately 100 actin subunits per binding event. These findings establish a paradigm, in which a filament end-binding protein and a side-binding protein work in concert to control actin dynamics, and help explain how rapid actin network depolymerization is achieved in cells.
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Affiliation(s)
- Shashank Shekhar
- Department of Biology, Brandeis University, Waltham, MA, 02454, USA
- Department of Physics, Brandeis University, Waltham, MA, 02454, USA
- Department of Biochemistry, Brandeis University, Waltham, MA, 02454, USA
| | - Johnson Chung
- Department of Biochemistry, Brandeis University, Waltham, MA, 02454, USA
| | - Jane Kondev
- Department of Physics, Brandeis University, Waltham, MA, 02454, USA
| | - Jeff Gelles
- Department of Biochemistry, Brandeis University, Waltham, MA, 02454, USA.
| | - Bruce L Goode
- Department of Biology, Brandeis University, Waltham, MA, 02454, USA.
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65
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Thomason EJ, Escalante M, Osterhout DJ, Fuss B. The oligodendrocyte growth cone and its actin cytoskeleton: A fundamental element for progenitor cell migration and CNS myelination. Glia 2019; 68:1329-1346. [PMID: 31696982 DOI: 10.1002/glia.23735] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/26/2019] [Accepted: 10/01/2019] [Indexed: 01/06/2023]
Abstract
Cells of the oligodendrocyte (OLG) lineage engage in highly motile behaviors that are crucial for effective central nervous system (CNS) myelination. These behaviors include the guided migration of OLG progenitor cells (OPCs), the surveying of local environments by cellular processes extending from differentiating and pre-myelinating OLGs, and during the process of active myelin wrapping, the forward movement of the leading edge of the myelin sheath's inner tongue along the axon. Almost all of these motile behaviors are driven by actin cytoskeletal dynamics initiated within a lamellipodial structure that is located at the tip of cellular OLG/OPC processes and is structurally as well as functionally similar to the neuronal growth cone. Accordingly, coordinated stoichiometries of actin filament (F-actin) assembly and disassembly at these OLG/OPC growth cones have been implicated in directing process outgrowth and guidance, and the initiation of myelination. Nonetheless, the functional importance of the OLG/OPC growth cone still remains to be fully understood, and, as a unique aspect of actin cytoskeletal dynamics, F-actin depolymerization and disassembly start to predominate at the transition from myelination initiation to myelin wrapping. This review provides an overview of the current knowledge about OLG/OPC growth cones, and it proposes a model in which actin cytoskeletal dynamics in OLG/OPC growth cones are a main driver for morphological transformations and motile behaviors. Remarkably, these activities, at least at the later stages of OLG maturation, may be regulated independently from the transcriptional gene expression changes typically associated with CNS myelination.
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Affiliation(s)
- Elizabeth J Thomason
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Miguel Escalante
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia.,Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, Mexico
| | - Donna J Osterhout
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Babette Fuss
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
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Funk J, Merino F, Venkova L, Heydenreich L, Kierfeld J, Vargas P, Raunser S, Piel M, Bieling P. Profilin and formin constitute a pacemaker system for robust actin filament growth. eLife 2019; 8:50963. [PMID: 31647411 PMCID: PMC6867828 DOI: 10.7554/elife.50963] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 10/24/2019] [Indexed: 12/19/2022] Open
Abstract
The actin cytoskeleton drives many essential biological processes, from cell morphogenesis to motility. Assembly of functional actin networks requires control over the speed at which actin filaments grow. How this can be achieved at the high and variable levels of soluble actin subunits found in cells is unclear. Here we reconstitute assembly of mammalian, non-muscle actin filaments from physiological concentrations of profilin-actin. We discover that under these conditions, filament growth is limited by profilin dissociating from the filament end and the speed of elongation becomes insensitive to the concentration of soluble subunits. Profilin release can be directly promoted by formin actin polymerases even at saturating profilin-actin concentrations. We demonstrate that mammalian cells indeed operate at the limit to actin filament growth imposed by profilin and formins. Our results reveal how synergy between profilin and formins generates robust filament growth rates that are resilient to changes in the soluble subunit concentration.
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Affiliation(s)
- Johanna Funk
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | | | - Jan Kierfeld
- Physics Department, TU Dortmund University, Dortmund, Germany
| | | | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
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67
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Velle KB, Fritz-Laylin LK. Diversity and evolution of actin-dependent phenotypes. Curr Opin Genet Dev 2019; 58-59:40-48. [DOI: 10.1016/j.gde.2019.07.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/19/2019] [Accepted: 07/20/2019] [Indexed: 12/20/2022]
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68
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Sakaguchi T, Takefuji M, Wettschureck N, Hamaguchi T, Amano M, Kato K, Tsuda T, Eguchi S, Ishihama S, Mori Y, Yura Y, Yoshida T, Unno K, Okumura T, Ishii H, Shimizu Y, Bando YK, Ohashi K, Ouchi N, Enomoto A, Offermanns S, Kaibuchi K, Murohara T. Protein Kinase N Promotes Stress-Induced Cardiac Dysfunction Through Phosphorylation of Myocardin-Related Transcription Factor A and Disruption of Its Interaction With Actin. Circulation 2019; 140:1737-1752. [PMID: 31564129 DOI: 10.1161/circulationaha.119.041019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Heart failure is a complex syndrome that results from structural or functional impairment of ventricular filling or blood ejection. Protein phosphorylation is a major and essential intracellular mechanism that mediates various cellular processes in cardiomyocytes in response to extracellular and intracellular signals. The RHOA-associated protein kinase (ROCK/Rho-kinase), an effector regulated by the small GTPase RHOA, causes pathological phosphorylation of proteins, resulting in cardiovascular diseases. RHOA also activates protein kinase N (PKN); however, the role of PKN in cardiovascular diseases remains unclear. METHODS To explore the role of PKNs in heart failure, we generated tamoxifen-inducible, cardiomyocyte-specific PKN1- and PKN2-knockout mice by intercrossing the αMHC-CreERT2 line with Pkn1flox/flox and Pkn2flox/flox mice and applied a mouse model of transverse aortic constriction- and angiotensin II-induced heart failure. To identify a novel substrate of PKNs, we incubated GST-tagged myocardin-related transcription factor A (MRTFA) with recombinant GST-PKN-catalytic domain or GST-ROCK-catalytic domain in the presence of radiolabeled ATP and detected radioactive GST-MRTFA as phosphorylated MRTFA. RESULTS We demonstrated that RHOA activates 2 members of the PKN family of proteins, PKN1 and PKN2, in cardiomyocytes of mice with cardiac dysfunction. Cardiomyocyte-specific deletion of the genes encoding Pkn1 and Pkn2 (cmc-PKN1/2 DKO) did not affect basal heart function but protected mice from pressure overload- and angiotensin II-induced cardiac dysfunction. Furthermore, we identified MRTFA as a novel substrate of PKN1 and PKN2 and found that MRTFA phosphorylation by PKN was considerably more effective than that by ROCK in vitro. We confirmed that endogenous MRTFA phosphorylation in the heart was induced by pressure overload- and angiotensin II-induced cardiac dysfunction in wild-type mice, whereas cmc-PKN1/2 DKO mice suppressed transverse aortic constriction- and angiotensin II-induced phosphorylation of MRTFA. Although RHOA-mediated actin polymerization accelerated MRTFA-induced gene transcription, PKN1 and PKN2 inhibited the interaction of MRTFA with globular actin by phosphorylating MRTFA, causing increased serum response factor-mediated expression of cardiac hypertrophy- and fibrosis-associated genes. CONCLUSIONS Our results indicate that PKN1 and PKN2 activation causes cardiac dysfunction and is involved in the transition to heart failure, thus providing unique targets for therapeutic intervention for heart failure.
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Affiliation(s)
- Teruhiro Sakaguchi
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Mikito Takefuji
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Nina Wettschureck
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (N.W., S.O.)
| | - Tomonari Hamaguchi
- Cell Pharmacology (T.H., M.A., Y.Y., K. Kaibuchi), Nagoya University School of Medicine, Japan
| | - Mutsuki Amano
- Cell Pharmacology (T.H., M.A., Y.Y., K. Kaibuchi), Nagoya University School of Medicine, Japan
| | - Katsuhiro Kato
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Takuma Tsuda
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Shunsuke Eguchi
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Sohta Ishihama
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Yu Mori
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Yoshimitsu Yura
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan.,Cell Pharmacology (T.H., M.A., Y.Y., K. Kaibuchi), Nagoya University School of Medicine, Japan
| | - Tatsuya Yoshida
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Kazumasa Unno
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Takahiro Okumura
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Hideki Ishii
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Yuuki Shimizu
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Yasuko K Bando
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
| | - Koji Ohashi
- Molecular Medicine and Cardiology (K.O., N.O.), Nagoya University School of Medicine, Japan
| | - Noriyuki Ouchi
- Molecular Medicine and Cardiology (K.O., N.O.), Nagoya University School of Medicine, Japan
| | - Atsushi Enomoto
- Pathology (A.E.), Nagoya University School of Medicine, Japan
| | - Stefan Offermanns
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (N.W., S.O.)
| | - Kozo Kaibuchi
- Cell Pharmacology (T.H., M.A., Y.Y., K. Kaibuchi), Nagoya University School of Medicine, Japan
| | - Toyoaki Murohara
- Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan
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Ni Q, Papoian GA. Turnover versus treadmilling in actin network assembly and remodeling. Cytoskeleton (Hoboken) 2019; 76:562-570. [PMID: 31525282 DOI: 10.1002/cm.21564] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 08/03/2019] [Accepted: 09/09/2019] [Indexed: 12/16/2022]
Abstract
Actin networks are highly dynamic cytoskeletal structures that continuously undergo structural remodeling. One prominent way to probe these processes is via Fluorescence Recovery After Photobleaching (FRAP), which can be used to estimate the rate of turnover for filamentous actin monomers. It is thought that head-to-tail treadmilling and de novo filament nucleation constitute two primary mechanisms underlying turnover kinetics. More generally, these self-assembly activities are responsible for many important cellular functions such as force generation, cellular shape dynamics, and cellular motility. In what relative proportions filament treadmilling and de novo filament nucleation contribute to actin network turnover is still not fully understood. We used an advanced stochastic reaction-diffusion model in three dimensions, MEDYAN, to study turnover dynamics of actin networks containing Arp2/3, formin and capping protein at experimentally meaningful length- and time-scales. Our results reveal that, most commonly, treadmilling of older filaments is the main contributor to actin network turnover. On the other hand, although turnover and treadmilling are often used interchangeably, we show clear instances where this assumption would not be justified, for example, finding that rapid turnover is accompanied by slow treadmilling in highly dendritic Arp2/3 networks.
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Affiliation(s)
- Qin Ni
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland
| | - Garegin A Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland.,Institute for Physical Science and Technology, University of Maryland, College Park, Maryland
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70
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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: 24] [Impact Index Per Article: 4.8] [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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71
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Zhang XF, Ajeti V, Tsai N, Fereydooni A, Burns W, Murrell M, De La Cruz EM, Forscher P. Regulation of axon growth by myosin II-dependent mechanocatalysis of cofilin activity. J Cell Biol 2019; 218:2329-2349. [PMID: 31123185 PMCID: PMC6605792 DOI: 10.1083/jcb.201810054] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 03/26/2019] [Accepted: 05/06/2019] [Indexed: 12/24/2022] Open
Abstract
Synergism between myosin II contractility and cofilin activity modulates serotonin-dependent axon growth. Normally, cofilin-dependent decreases in actin density are compensated by increases in point contact density and traction force; however, myosin hyperactivation leads to catastrophic decreases in actin network density and neurite retraction. Serotonin (5-HT) is known to increase the rate of growth cone advance via cofilin-dependent increases in retrograde actin network flow and nonmuscle myosin II activity. We report that myosin II activity is regulated by PKC during 5-HT responses and that PKC activity is necessary for increases in traction force normally associated with these growth responses. 5-HT simultaneously induces cofilin-dependent decreases in actin network density and PKC-dependent increases in point contact density. These reciprocal effects facilitate increases in traction force production in domains exhibiting decreased actin network density. Interestingly, when PKC activity was up-regulated, 5-HT treatments resulted in myosin II hyperactivation accompanied by catastrophic cofilin-dependent decreases in actin filament density, sudden decreases in traction force, and neurite retraction. These results reveal a synergistic relationship between cofilin and myosin II that is spatiotemporally regulated in the growth cone via mechanocatalytic effects to modulate neurite growth.
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Affiliation(s)
- Xiao-Feng Zhang
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT
| | - Visar Ajeti
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT.,Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT
| | - Nicole Tsai
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT.,Department of Ophthalmology, University of California, San Francisco, California, CA
| | - Arash Fereydooni
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT
| | - William Burns
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT
| | - Michael Murrell
- Department of Biomedical Engineering, Yale University, New Haven, CT
| | - Enrique M De La Cruz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT
| | - Paul Forscher
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT
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Manhart A, Icheva TA, Guerin C, Klar T, Boujemaa-Paterski R, Thery M, Blanchoin L, Mogilner A. Quantitative regulation of the dynamic steady state of actin networks. eLife 2019; 8:42413. [PMID: 30869077 PMCID: PMC6417862 DOI: 10.7554/elife.42413] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 02/26/2019] [Indexed: 12/30/2022] Open
Abstract
Principles of regulation of actin network dimensions are fundamentally important for cell functions, yet remain unclear. Using both in vitro and in silico approaches, we studied the effect of key parameters, such as actin density, ADF/Cofilin concentration and network width on the network length. In the presence of ADF/Cofilin, networks reached equilibrium and became treadmilling. At the trailing edge, the network disintegrated into large fragments. A mathematical model predicts the network length as a function of width, actin and ADF/Cofilin concentrations. Local depletion of ADF/Cofilin by binding to actin is significant, leading to wider networks growing longer. A single rate of breaking network nodes, proportional to ADF/Cofilin density and inversely proportional to the square of the actin density, can account for the disassembly dynamics. Selective disassembly of heterogeneous networks by ADF/Cofilin controls steering during motility. Our results establish general principles on how the dynamic steady state of actin network emerges from biochemical and structural feedbacks.
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Affiliation(s)
- Angelika Manhart
- Courant Institute of Mathematical Sciences, New York University, New York, United States.,Department of Biology, New York University, New York, United States
| | - Téa Aleksandra Icheva
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Christophe Guerin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Tobbias Klar
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Rajaa Boujemaa-Paterski
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Manuel Thery
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France.,CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, Paris, France
| | - Laurent Blanchoin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France.,CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, Paris, France
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences, New York University, New York, United States.,Department of Biology, New York University, New York, United States
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73
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Isogai T, Danuser G. Discovery of functional interactions among actin regulators by analysis of image fluctuations in an unperturbed motile cell system. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0110. [PMID: 29632262 DOI: 10.1098/rstb.2017.0110] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2017] [Indexed: 01/06/2023] Open
Abstract
Cell migration is driven by propulsive forces derived from polymerizing actin that pushes and extends the plasma membrane. The underlying actin network is constantly undergoing adaptation to new mechano-chemical environments and intracellular conditions. As such, mechanisms that regulate actin dynamics inherently contain multiple feedback loops and redundant pathways. Given the highly adaptable nature of such a system, studies that use only perturbation experiments (e.g. knockdowns, overexpression, pharmacological activation/inhibition, etc.) are challenged by the nonlinearity and redundancy of the pathway. In these pathway configurations, perturbation experiments at best describe the function(s) of a molecular component in an adapting (e.g. acutely drug-treated) or fully adapted (e.g. permanent gene silenced) cell system, where the targeted component now resides in a non-native equilibrium. Here, we propose how quantitative live-cell imaging and analysis of constitutive fluctuations of molecular activities can overcome these limitations. We highlight emerging actin filament barbed-end biology as a prime example of a complex, nonlinear molecular process that requires a fluctuation analytic approach, especially in an unperturbed cellular system, to decipher functional interactions of barbed-end regulators, actin polymerization and membrane protrusion.This article is part of the theme issue 'Self-organization in cell biology'.
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Affiliation(s)
- Tadamoto Isogai
- Department of Cell Biology, Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gaudenz Danuser
- Department of Cell Biology, Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX 75390, USA
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74
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Dekraker C, Boucher E, Mandato CA. Regulation and Assembly of Actomyosin Contractile Rings in Cytokinesis and Cell Repair. Anat Rec (Hoboken) 2018; 301:2051-2066. [PMID: 30312008 DOI: 10.1002/ar.23962] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 08/24/2018] [Accepted: 08/27/2018] [Indexed: 01/17/2023]
Abstract
Cytokinesis and single-cell wound repair both involve contractile assemblies of filamentous actin (F-actin) and myosin II organized into characteristic ring-like arrays. The assembly of these actomyosin contractile rings (CRs) is specified spatially and temporally by small Rho GTPases, which trigger local actin polymerization and myosin II contractility via a variety of downstream effectors. We now have a much clearer view of the Rho GTPase signaling cascade that leads to the formation of CRs, but some factors involved in CR positioning, assembly, and function remain poorly understood. Recent studies show that this regulation is multifactorial and goes beyond the long-established Ca2+ -dependent processes. There is substantial evidence that the Ca2+ -independent changes in cell shape, tension, and plasma membrane composition that characterize cytokinesis and single-cell wound repair also regulate CR formation. Elucidating the regulation and mechanistic properties of CRs is important to our understanding of basic cell biology and holds potential for therapeutic applications in human disease. In this review, we present a primer on the factors influencing and regulating CR positioning, assembly, and contraction as they occur in a variety of cytokinetic and single-cell wound repair models. Anat Rec, 301:2051-2066, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Corina Dekraker
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Eric Boucher
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Craig A Mandato
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
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75
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Parreno J, Fowler VM. Multifunctional roles of tropomodulin-3 in regulating actin dynamics. Biophys Rev 2018; 10:1605-1615. [PMID: 30430457 DOI: 10.1007/s12551-018-0481-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/08/2018] [Indexed: 12/12/2022] Open
Abstract
Tropomodulins (Tmods) are proteins that cap the slow-growing (pointed) ends of actin filaments (F-actin). The basis for our current understanding of Tmod function comes from studies in cells with relatively stable and highly organized F-actin networks, leading to the view that Tmod capping functions principally to preserve F-actin stability. However, not only is Tmod capping dynamic, but it also can play major roles in regulating diverse cellular processes involving F-actin remodeling. Here, we highlight the multifunctional roles of Tmod with a focus on Tmod3. Like other Tmods, Tmod3 binds tropomyosin (Tpm) and actin, capping pure F-actin at submicromolar and Tpm-coated F-actin at nanomolar concentrations. Unlike other Tmods, Tmod3 can also bind actin monomers and its ability to bind actin is inhibited by phosphorylation of Tmod3 by Akt2. Tmod3 is ubiquitously expressed and is present in a diverse array of cytoskeletal structures, including contractile structures such as sarcomere-like units of actomyosin stress fibers and in the F-actin network encompassing adherens junctions. Tmod3 participates in F-actin network remodeling in lamellipodia during cell migration and in the assembly of specialized F-actin networks during exocytosis. Furthermore, Tmod3 is required for development, regulating F-actin mesh formation during meiosis I of mouse oocytes, erythroblast enucleation in definitive erythropoiesis, and megakaryocyte morphogenesis in the mouse fetal liver. Thus, Tmod3 plays vital roles in dynamic and stable F-actin networks in cell physiology and development, with further research required to delineate the mechanistic details of Tmod3 regulation in the aforementioned processes, or in other yet to be discovered processes.
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Affiliation(s)
- Justin Parreno
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Velia M Fowler
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA, 92037, USA.
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76
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Holz D, Vavylonis D. Building a dendritic actin filament network branch by branch: models of filament orientation pattern and force generation in lamellipodia. Biophys Rev 2018; 10:1577-1585. [PMID: 30421277 DOI: 10.1007/s12551-018-0475-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 10/21/2018] [Indexed: 01/02/2023] Open
Abstract
We review mathematical and computational models of the structure, dynamics, and force generation properties of dendritic actin networks. These models have been motivated by the dendritic nucleation model, which provided a mechanistic picture of how the actin cytoskeleton system powers cell motility. We describe how they aimed to explain the self-organization of the branched network into a bimodal distribution of filament orientations peaked at 35° and - 35° with respect to the direction of membrane protrusion, as well as other patterns. Concave and convex force-velocity relationships were derived, depending on network organization, filament, and membrane elasticity and accounting for actin polymerization at the barbed end as a Brownian ratchet. This review also describes models that considered the kinetics and transport of actin and diffuse regulators and mechanical coupling to a substrate, together with explicit modeling of dendritic networks.
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Affiliation(s)
- Danielle Holz
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, PA, 18105, USA
| | - Dimitrios Vavylonis
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, PA, 18105, USA.
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77
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Assembling actin filaments for protrusion. Curr Opin Cell Biol 2018; 56:53-63. [PMID: 30278304 DOI: 10.1016/j.ceb.2018.09.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/10/2018] [Accepted: 09/17/2018] [Indexed: 12/31/2022]
Abstract
Cell migration entails a plethora of activities combining the productive exertion of protrusive and contractile forces to allow cells to push and squeeze themselves through cell clumps, interstitial tissues or tissue borders. All these activities require the generation and turnover of actin filaments that arrange into specific, subcellular structures. The most prominent structures mediating the protrusion at the leading edges of cells include lamellipodia and filopodia as well as plasma membrane blebs. Moreover, in cells migrating on planar substratum, mechanical support is being provided by an additional, more proximally located structure termed the lamella. Here, we systematically dissect the literature concerning the mechanisms driving actin filament nucleation and elongation in the best-studied protrusive structure, the lamellipodium. Recent work has shed light on open questions in lamellipodium protrusion, including the relative contributions of nucleation versus elongation to the assembly of both individual filaments and the lamellipodial network as a whole. However, much remains to be learned concerning the specificity and relevance of individual factors, their cooperation and their site-specific functions relative to the importance of global actin monomer and filament homeostasis.
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78
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Abstract
Fascia is a cacophony of functions and information, a completely adaptable entropy complex. The fascial system has a solid and a liquid component, acting in a perfect symbiotic synchrony. Each cell communicates with the other cells by sending and receiving signals; this concept is a part of quantum physics and it is known as quantum entanglement: a physical system cannot be described individually, but only as a juxtaposition of multiple systems, where the measurement of a quantity determines the value for other systems. Fascial continuum serves as a target for different manual approaches, such as physiotherapy, osteopathy and chiropractic. Cellular behaviour and the inclusion of quantum physics background are hardly being considered to find out what happens between the operator and the patient during a manual physical contact. The article examines these topics. According to the authors' knowledge, this is the first scientific text to offer manual operators’ new perspectives to understand what happens during palpatory contact. A fascial cell has not only memory but also the awareness of the mechanometabolic information it feels, and it has the anticipatory predisposition in preparing itself for alteration of its natural environment.
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Affiliation(s)
- Bruno Bordoni
- Cardiology, Foundation Don Carlo Gnocchi / (IRCCS) Institute of Hospitalization and Care, Milano, ITA
| | - Marta Simonelli
- Osteopathy, (SOFI) School of French-Italian Osteopathy, Pisa, ITA
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79
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Abstract
A buffer reaction actively resists changes to the concentration of a chemical species. Typically, buffering reactions have only been able to regulate the concentration of hydronium (i.e., pH) and other ions. Here, we develop a new class of buffers that regulate the concentrations of short sequences of DNA (i.e., oligonucleotides). A buffer's behavior is determined by its set point concentration, capacity to resist disturbances, and response time after a disturbance. We provide simple mathematical formulas for selecting rate constants to tune each of these properties and show how to design DNA sequences and concentrations to implement the desired rate constants. We demonstrate several oligonucleotide buffers that maintain oligonucleotide set point concentrations between 10 and 80 nM in the presence of disturbances of 50 to 500 nM, with response times of less than 10 min to 1.5 h. Multiple buffers can regulate different sequences of DNA in parallel without crosstalk. Oligonucleotide buffers could stabilize and restore reactant concentrations in DNA circuits or in self-assembly processes, allowing such systems to operate reliably for extended durations. These buffers might also be coupled to other reactions to buffer molecules other than DNA. In general, an oligonucleotide buffer can be viewed as a chemical "battery" that maintains the total chemical potential of a buffered species in a closed system.
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80
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Quinlan RA, Schwarz N, Windoffer R, Richardson C, Hawkins T, Broussard JA, Green KJ, Leube RE. A rim-and-spoke hypothesis to explain the biomechanical roles for cytoplasmic intermediate filament networks. J Cell Sci 2018; 130:3437-3445. [PMID: 29032358 DOI: 10.1242/jcs.202168] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 08/02/2017] [Indexed: 12/17/2022] Open
Abstract
Textbook images of keratin intermediate filament (IF) networks in epithelial cells and the functional compromization of the epidermis by keratin mutations promulgate a mechanical role for this important cytoskeletal component. In stratified epithelia, keratin filaments form prominent radial spokes that are focused onto cell-cell contact sites, i.e. the desmosomes. In this Hypothesis, we draw attention to a subset of keratin filaments that are apposed to the plasma membrane. They form a rim of filaments interconnecting the desmosomes in a circumferential network. We hypothesize that they are part of a rim-and-spoke arrangement of IFs in epithelia. From our review of the literature, we extend this functional role for the subplasmalemmal rim of IFs to any cell, in which plasma membrane support is required, provided these filaments connect directly or indirectly to the plasma membrane. Furthermore, cytoplasmic IF networks physically link the outer nuclear and plasma membranes, but their participation in mechanotransduction processes remain largely unconsidered. Therefore, we also discuss the potential biomechanical and mechanosensory role(s) of the cytoplasmic IF network in terms of such a rim (i.e. subplasmalemmal)-and-spoke arrangement for cytoplasmic IF networks.
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Affiliation(s)
- Roy A Quinlan
- Department of Biosciences, University of Durham, Upper Mountjoy, Stockton Road, Durham DH1 3LE, UK .,Biophysical Sciences Institute, University of Durham, Upper Mountjoy, Stockton Road, Durham DH1 3LE, UK
| | - Nicole Schwarz
- RWTH Aachen University, Institute of Molecular and Cellular Anatomy, Wendlingweg 2, 52074 Aachen, Germany
| | - Reinhard Windoffer
- RWTH Aachen University, Institute of Molecular and Cellular Anatomy, Wendlingweg 2, 52074 Aachen, Germany
| | - Christine Richardson
- Department of Biosciences, University of Durham, Upper Mountjoy, Stockton Road, Durham DH1 3LE, UK
| | - Tim Hawkins
- Department of Biosciences, University of Durham, Upper Mountjoy, Stockton Road, Durham DH1 3LE, UK
| | - Joshua A Broussard
- Dept. of Pathology W127, Tarry Bldg, Room 3-735, Northwestern University, Feinberg School of Medicine, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | - Kathleen J Green
- Dept. of Pathology W127, Tarry Bldg, Room 3-735, Northwestern University, Feinberg School of Medicine, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | - Rudolf E Leube
- RWTH Aachen University, Institute of Molecular and Cellular Anatomy, Wendlingweg 2, 52074 Aachen, Germany
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81
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Kotila T, Kogan K, Enkavi G, Guo S, Vattulainen I, Goode BL, Lappalainen P. Structural basis of actin monomer re-charging by cyclase-associated protein. Nat Commun 2018; 9:1892. [PMID: 29760438 PMCID: PMC5951797 DOI: 10.1038/s41467-018-04231-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 04/13/2018] [Indexed: 11/10/2022] Open
Abstract
Actin polymerization powers key cellular processes, including motility, morphogenesis, and endocytosis. The actin turnover cycle depends critically on "re-charging" of ADP-actin monomers with ATP, but whether this reaction requires dedicated proteins in cells, and the underlying mechanism, have remained elusive. Here we report that nucleotide exchange catalyzed by the ubiquitous cytoskeletal regulator cyclase-associated protein (CAP) is critical for actin-based processes in vivo. We determine the structure of the CAP-actin complex, which reveals that nucleotide exchange occurs in a compact, sandwich-like complex formed between the dimeric actin-binding domain of CAP and two ADP-actin monomers. In the crystal structure, the C-terminal tail of CAP associates with the nucleotide-sensing region of actin, and this interaction is required for rapid re-charging of actin by both yeast and mammalian CAPs. These data uncover the conserved structural basis and biological role of protein-catalyzed re-charging of actin monomers.
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Affiliation(s)
- Tommi Kotila
- Institute of Biotechnology, University of Helsinki, 00014, Helsinki, Finland
| | - Konstantin Kogan
- Institute of Biotechnology, University of Helsinki, 00014, Helsinki, Finland
| | - Giray Enkavi
- Department of Physics, University of Helsinki, 00014, Helsinki, Finland
| | - Siyang Guo
- Department of Biology, Brandeis University, Waltham, MA, 02453, USA
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, 00014, Helsinki, Finland
- Laboratory of Physics, Tampere University of Technology, 33101, Tampere, Finland
| | - Bruce L Goode
- Department of Biology, Brandeis University, Waltham, MA, 02453, USA
| | - Pekka Lappalainen
- Institute of Biotechnology, University of Helsinki, 00014, Helsinki, Finland.
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82
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Abstract
How do the cells in our body reconfigure their shape to achieve complex tasks like migration and mitosis, yet maintain their shape in response to forces exerted by, for instance, blood flow and muscle action? Cell shape control is defined by a delicate mechanical balance between active force generation and passive material properties of the plasma membrane and the cytoskeleton. The cytoskeleton forms a space-spanning fibrous network comprising three subsystems: actin, microtubules and intermediate filaments. Bottom-up reconstitution of minimal synthetic cells where these cytoskeletal subsystems are encapsulated inside a lipid vesicle provides a powerful avenue to dissect the force balance that governs cell shape control. Although encapsulation is technically demanding, a steady stream of advances in this technique has made the reconstitution of shape-changing minimal cells increasingly feasible. In this topical review we provide a route-map of the recent advances in cytoskeletal encapsulation techniques and outline recent reports that demonstrate shape change phenomena in simple biomimetic vesicle systems. We end with an outlook toward the next steps required to achieve more complex shape changes with the ultimate aim of building a fully functional synthetic cell with the capability to autonomously grow, divide and move.
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Affiliation(s)
- Yuval Mulla
- These authors contributed equally to this work
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83
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Wille C, Eiseler T, Langenberger ST, Richter J, Mizuno K, Radermacher P, Knippschild U, Huber-Lang M, Seufferlein T, Paschke S. PKD regulates actin polymerization, neutrophil deformability, and transendothelial migration in response to fMLP and trauma. J Leukoc Biol 2018; 104:615-630. [PMID: 29656400 DOI: 10.1002/jlb.4a0617-251rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 02/20/2018] [Accepted: 03/19/2018] [Indexed: 12/17/2022] Open
Abstract
Neutrophils are important mediators of the innate immune defense and of the host response to a physical trauma. Because aberrant infiltration of injured sites by neutrophils was shown to cause adverse effects after trauma, we investigated how neutrophil infiltration could be modulated at the cellular level. Our data indicate that protein kinase D (PKD) is a vital regulator of neutrophil transmigration. PKD phosphorylates the Cofilin-phosphatase Slingshot-2L (SSH-2L). SSH-2L in turn dynamically regulates Cofilin activity and actin polymerization in response to a chemotactic stimulus for neutrophils, for example, fMLP. Here, we show that inhibition of PKD by two specific small molecule inhibitors results in broad, unrestricted activation of Cofilin and strongly increases the F-actin content of neutrophils even under basal conditions. This phenotype correlates with a significantly impaired neutrophil deformability as determined by optical stretcher analysis. Consequently, inhibition of PKD impaired chemotaxis as shown by reduced extravasation of neutrophils. Consequently, we demonstrate that transendothelial passage of both, neutrophil-like NB4 cells and primary PMNs recovered from a hemorrhagic shock trauma model was significantly reduced. Thus, inhibition of PKD may represent a promising modulator of the neutrophil response to trauma.
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Affiliation(s)
- Christoph Wille
- Department of Internal Medicine I, Ulm University, Ulm, Germany
| | - Tim Eiseler
- Department of Internal Medicine I, Ulm University, Ulm, Germany
| | | | - Julia Richter
- Department of General and Visceral Surgery, Ulm University, Ulm, Germany
| | - Kensaku Mizuno
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Peter Radermacher
- Institute of Anesthesiological Pathophysiology and Process Engineering, University Hospital, Ulm, Germany
| | - Uwe Knippschild
- Department of General and Visceral Surgery, Ulm University, Ulm, Germany
| | - Markus Huber-Lang
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital, Ulm, Germany
| | | | - Stephan Paschke
- Department of General and Visceral Surgery, Ulm University, Ulm, Germany
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84
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Ozdemir ES, Jang H, Gursoy A, Keskin O, Li Z, Sacks DB, Nussinov R. Unraveling the molecular mechanism of interactions of the Rho GTPases Cdc42 and Rac1 with the scaffolding protein IQGAP2. J Biol Chem 2018; 293:3685-3699. [PMID: 29358323 PMCID: PMC5846150 DOI: 10.1074/jbc.ra117.001596] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 01/12/2018] [Indexed: 12/22/2022] Open
Abstract
IQ motif-containing GTPase-activating proteins (IQGAPs) are scaffolding proteins playing central roles in cell-cell adhesion, polarity, and motility. The Rho GTPases Cdc42 and Rac1, in their GTP-bound active forms, interact with all three human IQGAPs. The IQGAP-Cdc42 interaction promotes metastasis by enhancing actin polymerization. However, despite their high sequence identity, Cdc42 and Rac1 differ in their interactions with IQGAP. Two Cdc42 molecules can bind to the Ex-domain and the RasGAP site of the GTPase-activating protein (GAP)-related domain (GRD) of IQGAP and promote IQGAP dimerization. Only one Rac1 molecule might bind to the RasGAP site of GRD and may not facilitate the dimerization, and the exact mechanism of Cdc42 and Rac1 binding to IQGAP is unclear. Using all-atom molecular dynamics simulations, site-directed mutagenesis, and Western blotting, we unraveled the detailed mechanisms of Cdc42 and Rac1 interactions with IQGAP2. We observed that Cdc42 binding to the Ex-domain of GRD of IQGAP2 (GRD2) releases the Ex-domain at the C-terminal region of GRD2, facilitating IQGAP2 dimerization. Cdc42 binding to the Ex-domain promoted allosteric changes in the RasGAP site, providing a binding site for the second Cdc42 in the RasGAP site. Of note, the Cdc42 "insert loop" was important for the interaction of the first Cdc42 with the Ex-domain. By contrast, differences in Rac1 insert-loop sequence and structure precluded its interaction with the Ex-domain. Rac1 could bind only to the RasGAP site of apo-GRD2 and could not facilitate IQGAP2 dimerization. Our detailed mechanistic insights help decipher how Cdc42 can stimulate actin polymerization in metastasis.
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Affiliation(s)
- E Sila Ozdemir
- From the Departments of Chemical and Biological Engineering and
| | - Hyunbum Jang
- the Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, NCI-Frederick, Frederick, Maryland 21702
| | - Attila Gursoy
- Computer Engineering, Koc University, Istanbul 34450, Turkey,
| | - Ozlem Keskin
- From the Departments of Chemical and Biological Engineering and
| | - Zhigang Li
- the Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892, and
| | - David B Sacks
- the Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Ruth Nussinov
- the Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, NCI-Frederick, Frederick, Maryland 21702,
- the Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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85
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Shekhar S. Microfluidics-Assisted TIRF Imaging to Study Single Actin Filament Dynamics. ACTA ACUST UNITED AC 2017; 77:12.13.1-12.13.24. [PMID: 29227552 DOI: 10.1002/cpcb.31] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Dynamic assembly of actin filaments is essential for many cellular processes. The rates of assembly and disassembly of actin filaments are intricately controlled by regulatory proteins that interact with the ends and the sides of filaments and with actin monomers. TIRF-based single-filament imaging techniques have proven instrumental in uncovering mechanisms of actin regulation. In this unit, novel single-filament approaches using microfluidics-assisted TIRF imaging are described. These methods can be used to grow anchored actin filaments aligned in a flow, thus making the analysis much easier as compared to open flow cell approaches. The microfluidic nature of the system also enables rapid change of biochemical conditions and allows simultaneous imaging of a large number of actin filaments. Support protocols for preparing microfluidic chambers and purifying spectrin-actin seeds used for nucleating anchored filaments are also described. © 2017 by John Wiley & Sons, Inc.
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Affiliation(s)
- Shashank Shekhar
- Department of Biochemistry, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts
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86
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Kikumoto M, Oosawa F. Thermodynamic measurements of actin polymerization with various cation species. Cytoskeleton (Hoboken) 2017; 74:465-471. [PMID: 29080281 DOI: 10.1002/cm.21416] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 09/26/2017] [Accepted: 10/13/2017] [Indexed: 12/28/2022]
Abstract
We measured the critical concentration of actin polymerized with different polymerization ions and bound divalent cations at low temperatures and estimated thermodynamic parameters. The entropy and enthalpy changes of actin polymerization were 36-55 (cal/mol K) and 2-8 (kcal/mol), respectively, with some exceptions. Both the entropy and enthalpy changes of the polymerization of Ca2+ -actin were sensitive to the polymerization ion (K+ or Na+ ): ΔS = 39 or 36 (cal/mol K), ΔΗ= 3.9 or 2.7 (kcal/mol). The entropy and enthalpy changes (cal/mol K, kcal/mol) of Mg2+ -actin were also sensitive to the polymerization ion in the following order: Mg2+ (55, 7.6) > K+ (46, 5.3) > Na+ (38, 2.4). Those values largely decreased and became even negative in the presence of a high concentration (0.1 M) of K+ , which was likely caused by the charge screening effect of that ion.
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Affiliation(s)
- Mahito Kikumoto
- Structural Biology Research Center, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Fumio Oosawa
- Graduate School of Science, Nagoya University, Professor Emeritus of Nagoya University, Nagoya/Graduate School of Engineering Science, Osaka University, Professor Emeritus of Osaka University, Suita, Japan
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87
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Sonn-Segev A, Bernheim-Groswasser A, Roichman Y. Scale dependence of the mechanics of active gels with increasing motor concentration. SOFT MATTER 2017; 13:7352-7359. [PMID: 28951910 DOI: 10.1039/c7sm01391d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Actin is a protein that plays an essential role in maintaining the mechanical integrity of cells. In response to strong external stresses, it can assemble into large bundles, but it grows into a fine branched network to induce cell motion. In some cases, the self-organization of actin fibers and networks involves the action of bipolar filaments of the molecular motor myosin. Such self-organization processes mediated by large myosin bipolar filaments have been studied extensively in vitro. Here we create active gels, composed of single actin filaments and small myosin bipolar filaments. The active steady state in these gels persists long enough to enable the characterization of their mechanical properties using one and two point microrheology. We study the effect of myosin concentration on the mechanical properties of this model system for active matter, for two different motor assembly sizes. In contrast to previous studies of networks with large motor assemblies, we find that the fluctuations of tracer particles embedded in the network decrease in amplitude as motor concentration increases. Nonetheless, we show that myosin motors stiffen the actin networks, in accordance with bulk rheology measurements of networks containing larger motor assemblies. This implies that such stiffening is of universal nature and may be relevant to a wider range of cytoskeleton-based structures.
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Affiliation(s)
- Adar Sonn-Segev
- Raymond & Beverly Sackler School of Chemistry, Tel Aviv University, Tel Aviv 6997801, Israel.
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88
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Shekhar S, Carlier MF. Enhanced Depolymerization of Actin Filaments by ADF/Cofilin and Monomer Funneling by Capping Protein Cooperate to Accelerate Barbed-End Growth. Curr Biol 2017. [PMID: 28625780 PMCID: PMC5505869 DOI: 10.1016/j.cub.2017.05.036] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A living cell’s ability to assemble actin filaments in intracellular motile processes is directly dependent on the availability of polymerizable actin monomers, which feed polarized filament growth [1, 2]. Continued generation of the monomer pool by filament disassembly is therefore crucial. Disassemblers like actin depolymerizing factor (ADF)/cofilin and filament cappers like capping protein (CP) are essential agonists of motility [3, 4, 5, 6, 7, 8], but the exact molecular mechanisms by which they accelerate actin polymerization at the leading edge and filament turnover has been debated for over two decades [9, 10, 11, 12]. Whereas filament fragmentation by ADF/cofilin has long been demonstrated by total internal reflection fluorescence (TIRF) [13, 14], filament depolymerization was only inferred from bulk solution assays [15]. Using microfluidics-assisted TIRF microscopy, we provide the first direct visual evidence of ADF’s simultaneous severing and rapid depolymerization of individual filaments. Using a conceptually novel assay to directly visualize ADF’s effect on a population of pre-assembled filaments, we demonstrate how ADF’s enhanced pointed-end depolymerization causes an increase in polymerizable actin monomers, thus promoting faster barbed-end growth. We further reveal that ADF-enhanced depolymerization synergizes with CP’s long-predicted “monomer funneling” [16] and leads to skyrocketing of filament growth rates, close to estimated lamellipodial rates. The “funneling model” hypothesized, on thermodynamic grounds, that at high enough extent of capping, the few non-capped filaments transiently grow much faster [15], an effect proposed to be very important for motility. We provide the first direct microscopic evidence of monomer funneling at the scale of individual filaments. These results significantly enhance our understanding of the turnover of cellular actin networks. ADF enhances barbed- and pointed-end depolymerization of actin filaments Capping protein funnels monomers from all pointed ends to the few non-capped barbed ends ADF and capping protein synergy leads to skyrocketing of filament elongation rates
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Affiliation(s)
- Shashank Shekhar
- Cytoskeleton Dynamics and Cell Motility, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris Saclay, 91198 Gif-sur-Yvette Cedex, France.
| | - Marie-France Carlier
- Cytoskeleton Dynamics and Cell Motility, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris Saclay, 91198 Gif-sur-Yvette Cedex, France.
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