151
|
Higgs HN. A fruitful tree: developing the dendritic nucleation model of actin-based cell motility. Mol Biol Cell 2018. [PMCID: PMC6333179 DOI: 10.1091/mbc.e18-07-0426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
A fundamental question in cell biology concerns how cells move, and this has been the subject of intense research for decades. In the 1990s, a major leap forward was made in our understanding of cell motility, with the proposal of the dendritic nucleation model. This essay describes the events leading to the development of the model, including findings from many laboratories and scientific disciplines. The story is an excellent example of the scientific process in action, with the combination of multiple perspectives leading to robust conclusions.
Collapse
Affiliation(s)
- Henry N. Higgs
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| |
Collapse
|
152
|
Gagat M, Hałas-Wiśniewska M, Zielińska W, Izdebska M, Grzanka D, Grzanka A. The effect of piperlongumine on endothelial and lung adenocarcinoma cells with regulated expression of profilin-1. Onco Targets Ther 2018; 11:8275-8292. [PMID: 30538497 PMCID: PMC6255113 DOI: 10.2147/ott.s183191] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose The aim of the study was to evaluate the effect of piperlongumine (2 and 4 µM) on endothelial EA.hy926 and lung adenocarcinoma A549 cells with regulated expression of profilin-1 (PFN1). Material and methods The cytotoxicity of alkaloid was evaluated by MTT assay, while cell death was assessed using double staining with annexin V and propidium iodide. Subsequently, the level of PFN1 1) upregulation in EA.hy926 endothelial cells and 2) downregulation in A549 lung adenocarcinoma cells. The next step was the analysis of the effect of PFN1 manipulation on cytoskeletal proteins. Results The results showed that piperlongumine may inhibit proliferation of EA.hy926 and A549 cell lines and also induce cell death in a dose-dependent manner. Furthermore, endothelial cells with PFN1 overexpression showed lower sensitivity to alkaloid and strengthening of cell-cell interactions. In the case of A549 cells, loss of PFN1 expression resulted in a lower percentage of early apoptotic cells, reorganization of F-actin and vimentin network, and reduction of migratory potential. Conclusion We suggest that upregulation of PFN1 in endothelial cell line may stabilize the cell junctions. In turn, PFN1 downregulation in A549 cells probably suppresses cell migration and sensitizes cells to anticancer agents.
Collapse
Affiliation(s)
- Maciej Gagat
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
| | - Marta Hałas-Wiśniewska
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
| | - Wioletta Zielińska
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
| | - Magdalena Izdebska
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
| | - Dariusz Grzanka
- Department of Clinical Pathomorphology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland
| | - Alina Grzanka
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
| |
Collapse
|
153
|
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.
Collapse
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.
| |
Collapse
|
154
|
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.
Collapse
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.
| |
Collapse
|
155
|
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.
Collapse
|
156
|
The Mechanobiology of the Actin Cytoskeleton in Stem Cells during Differentiation and Interaction with Biomaterials. Stem Cells Int 2018; 2018:2891957. [PMID: 30402108 PMCID: PMC6196919 DOI: 10.1155/2018/2891957] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 08/03/2018] [Accepted: 08/16/2018] [Indexed: 12/27/2022] Open
Abstract
An understanding of the cytoskeleton's importance in stem cells is essential for their manipulation and further clinical application. The cytoskeleton is crucial in stem cell biology and depends on physical and chemicals signals to define its structure. Additionally, cell culture conditions will be important in the proper maintenance of stemness, lineage commitment, and differentiation. This review focuses on the following areas: the role of the actin cytoskeleton of stem cells during differentiation, the significance of cellular morphology, signaling pathways involved in cytoskeletal rearrangement in stem cells, and the mechanobiology and mechanotransduction processes implicated in the interactions of stem cells with different surfaces of biomaterials, such as nanotopography, which is a physical cue influencing the differentiation of stem cells. Also, cancer stem cells are included since it is necessary to understand the role of their mechanical properties to develop new strategies to treat cancer. In this context, to study the stem cells requires integrated disciplines, including molecular and cellular biology, chemistry, physics, and immunology, as well as mechanobiology. Finally, since one of the purposes of studying stem cells is for their application in regenerative medicine, the deepest understanding is necessary in order to establish safety protocols and effective cell-based therapies.
Collapse
|
157
|
Lipchinsky A. Electromechanics of polarized cell growth. Biosystems 2018; 173:114-132. [PMID: 30300677 DOI: 10.1016/j.biosystems.2018.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/30/2018] [Accepted: 10/04/2018] [Indexed: 10/28/2022]
Abstract
One of the most challenging questions in cell and developmental biology is how molecular signals are translated into mechanical forces that ultimately drive cell growth and motility. Despite an impressive body of literature demonstrating the importance of cytoskeletal and motor proteins as well as osmotic stresses for cell developmental mechanics, a host of dissenting evidence strongly suggests that these factors per se cannot explain growth mechanics even at the level of a single tip-growing cell. The present study addresses this issue by exploring fundamental interrelations between electrical and mechanical fields operating in cells. In the first instance, we employ a simplified but instructive model of a quiescent cell to demonstrate that even in a quasi-equilibrium state, ion transport processes are conditioned principally by mechanical tenets. Then we inquire into the electromechanical conjugacy in growing pollen tubes as biologically relevant and physically tractable developmental systems owing to their extensively characterized growth-associated ionic fluxes and strikingly polarized growth and morphology. A comprehensive analysis of the multifold stress pattern in the growing apices of pollen tubes suggests that tip-focused ionic fluxes passing through the polyelectrolyte-rich apical cytoplasm give rise to electrokinetic flows that actualize otherwise isotropic intracellular turgor into anisotropic stress field. The stress anisotropy can be then imparted from the apical cytoplasm to the abutting frontal cell wall to induce its local extension and directional cell growth. Converging lines of evidence explored in the concluding sections attest that tip-focused ionic fluxes and associated interfacial transport phenomena are not specific for pollen tubes but are also employed by a vast variety of algal, plant, fungal and animal cells, rendering their cytoplasmic stress fields essentially anisotropic and ultimately instrumental in cell shaping, growth and motility.
Collapse
Affiliation(s)
- Andrei Lipchinsky
- Department of Plant Physiology and Biochemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg, 199034, Russia.
| |
Collapse
|
158
|
Klages-Mundt NL, Kumar A, Zhang Y, Kapoor P, Shen X. The Nature of Actin-Family Proteins in Chromatin-Modifying Complexes. Front Genet 2018; 9:398. [PMID: 30319687 PMCID: PMC6167448 DOI: 10.3389/fgene.2018.00398] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/31/2018] [Indexed: 01/25/2023] Open
Abstract
Actin is not only one of the most abundant proteins in eukaryotic cells, but also one of the most versatile. In addition to its familiar involvement in enabling contraction and establishing cellular motility and scaffolding in the cytosol, actin has well-documented roles in a variety of processes within the confines of the nucleus, such as transcriptional regulation and DNA repair. Interestingly, monomeric actin as well as actin-related proteins (Arps) are found as stoichiometric subunits of a variety of chromatin remodeling complexes and histone acetyltransferases, raising the question of precisely what roles they serve in these contexts. Actin and Arps are present in unique combinations in chromatin modifiers, helping to establish structural integrity of the complex and enabling a wide range of functions, such as recruiting the complex to nucleosomes to facilitate chromatin remodeling and promoting ATPase activity of the catalytic subunit. Actin and Arps are also thought to help modulate chromatin dynamics and maintain higher-order chromatin structure. Moreover, the presence of actin and Arps in several chromatin modifiers is necessary for promoting genomic integrity and an effective DNA damage response. In this review, we discuss the involvement of actin and Arps in these nuclear complexes that control chromatin remodeling and histone modifications, while also considering avenues for future study to further shed light on their functional importance.
Collapse
Affiliation(s)
- Naeh L Klages-Mundt
- Science Park Research Division, Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, United States.,Program in Genetics & Epigenetics, The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
| | - Ashok Kumar
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, United States
| | - Yuexuan Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Prabodh Kapoor
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, United States
| | - Xuetong Shen
- Science Park Research Division, Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, United States.,Program in Genetics & Epigenetics, The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
| |
Collapse
|
159
|
Tsai FC, Bertin A, Bousquet H, Manzi J, Senju Y, Tsai MC, Picas L, Miserey-Lenkei S, Lappalainen P, Lemichez E, Coudrier E, Bassereau P. Ezrin enrichment on curved membranes requires a specific conformation or interaction with a curvature-sensitive partner. eLife 2018; 7:37262. [PMID: 30234483 PMCID: PMC6167055 DOI: 10.7554/elife.37262] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 09/14/2018] [Indexed: 01/12/2023] Open
Abstract
One challenge in cell biology is to decipher the biophysical mechanisms governing protein enrichment on curved membranes and the resulting membrane deformation. The ERM protein ezrin is abundant and associated with cellular membranes that are flat, positively or negatively curved. Using in vitro and cell biology approaches, we assess mechanisms of ezrin’s enrichment on curved membranes. We evidence that wild-type ezrin (ezrinWT) and its phosphomimetic mutant T567D (ezrinTD) do not deform membranes but self-assemble anti-parallelly, zipping adjacent membranes. EzrinTD’s specific conformation reduces intermolecular interactions, allows binding to actin filaments, which reduces membrane tethering, and promotes ezrin binding to positively-curved membranes. While neither ezrinTD nor ezrinWT senses negative curvature alone, we demonstrate that interacting with curvature-sensing I-BAR-domain proteins facilitates ezrin enrichment in negatively-curved membrane protrusions. Overall, our work demonstrates that ezrin can tether membranes, or be targeted to curved membranes, depending on conformations and interactions with actin and curvature-sensing binding partners.
Collapse
Affiliation(s)
- Feng-Ching Tsai
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| | - Aurelie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| | - Hugo Bousquet
- Sorbonne Université, Paris, France.,Compartimentation et dynamique cellulaire, Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - John Manzi
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| | - Yosuke Senju
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Meng-Chen Tsai
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France.,Département de Microbiologie, Unité des Toxines Bactériennes, Université Paris Descartes, Institut Pasteur, Paris, France
| | - Laura Picas
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR 9004, Montpellier, France
| | - Stephanie Miserey-Lenkei
- Sorbonne Université, Paris, France.,Compartimentation et dynamique cellulaire, Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - Pekka Lappalainen
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Emmanuel Lemichez
- Département de Microbiologie, Unité des Toxines Bactériennes, Université Paris Descartes, Institut Pasteur, Paris, France
| | - Evelyne Coudrier
- Sorbonne Université, Paris, France.,Compartimentation et dynamique cellulaire, Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - Patricia Bassereau
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| |
Collapse
|
160
|
Wu H, de León MAP, Othmer HG. Getting in shape and swimming: the role of cortical forces and membrane heterogeneity in eukaryotic cells. J Math Biol 2018; 77:595-626. [PMID: 29480329 PMCID: PMC6109630 DOI: 10.1007/s00285-018-1223-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 02/12/2018] [Indexed: 12/14/2022]
Abstract
Recent research has shown that motile cells can adapt their mode of propulsion to the mechanical properties of the environment in which they find themselves-crawling in some environments while swimming in others. The latter can involve movement by blebbing or other cyclic shape changes, and both highly-simplified and more realistic models of these modes have been studied previously. Herein we study swimming that is driven by membrane tension gradients that arise from flows in the actin cortex underlying the membrane, and does not involve imposed cyclic shape changes. Such gradients can lead to a number of different characteristic cell shapes, and our first objective is to understand how different distributions of membrane tension influence the shape of cells in an inviscid quiescent fluid. We then analyze the effects of spatial variation in other membrane properties, and how they interact with tension gradients to determine the shape. We also study the effect of fluid-cell interactions and show how tension leads to cell movement, how the balance between tension gradients and a variable bending modulus determine the shape and direction of movement, and how the efficiency of movement depends on the properties of the fluid and the distribution of tension and bending modulus in the membrane.
Collapse
Affiliation(s)
- Hao Wu
- School of Mathematics, University of Minnesota, 270A Vincent Hall, Minneapolis, MN, USA
| | | | - Hans G Othmer
- School of Mathematics, University of Minnesota, 270A Vincent Hall, Minneapolis, MN, USA.
| |
Collapse
|
161
|
Conformational changes in Arp2/3 complex induced by ATP, WASp-VCA, and actin filaments. Proc Natl Acad Sci U S A 2018; 115:E8642-E8651. [PMID: 30150414 DOI: 10.1073/pnas.1717594115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
We used fluorescence spectroscopy and EM to determine how binding of ATP, nucleation-promoting factors, actin monomers, and actin filaments changes the conformation of Arp2/3 complex during the process that nucleates an actin filament branch. We mutated subunits of Schizosaccharomyces pombe Arp2/3 complex for labeling with fluorescent dyes at either the C termini of Arp2 and Arp3 or ArpC1 and ArpC3. We measured Förster resonance energy transfer (FRET) efficiency (ETeff) between the dyes in the presence of the various ligands. We also computed class averages from electron micrographs of negatively stained specimens. ATP binding made small conformational changes of the nucleotide-binding cleft of the Arp2 subunit. WASp-VCA, WASp-CA, and WASp-actin-VCA changed the ETeff between the dyes on the Arp2 and Arp3 subunits much more than between dyes on ArpC1 and ArpC3. Ensemble FRET detected an additional structural change that brought ArpC1 and ArpC3 closer together when Arp2/3 complex bound actin filaments. VCA binding to Arp2/3 complex causes a conformational change that favors binding to the side of an actin filament, which allows further changes required to nucleate a daughter filament.
Collapse
|
162
|
Plastino J, Blanchoin L. Dynamic stability of the actin ecosystem. J Cell Sci 2018; 132:132/4/jcs219832. [PMID: 30104258 DOI: 10.1242/jcs.219832] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
In cells, actin filaments continuously assemble and disassemble while maintaining an apparently constant network structure. This suggests a perfect balance between dynamic processes. Such behavior, operating far out of equilibrium by the hydrolysis of ATP, is called a dynamic steady state. This dynamic steady state confers a high degree of plasticity to cytoskeleton networks that allows them to adapt and optimize their architecture in response to external changes on short time-scales, thus permitting cells to adjust to their environment. In this Review, we summarize what is known about the cellular actin steady state, and what gaps remain in our understanding of this fundamental dynamic process that balances the different forms of actin organization in a cell. We focus on the minimal steps to achieve a steady state, discuss the potential feedback mechanisms at play to balance this steady state and conclude with an outlook on what is needed to fully understand its molecular nature.
Collapse
Affiliation(s)
- Julie Plastino
- Institut Curie, PSL Research University, CNRS, 75005 Paris, France .,Sorbonne Université, 75005 Paris, France
| | - Laurent Blanchoin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054 Grenoble, France .,CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hématologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, 75010 Paris, France
| |
Collapse
|
163
|
Boyer NP, Gupton SL. Revisiting Netrin-1: One Who Guides (Axons). Front Cell Neurosci 2018; 12:221. [PMID: 30108487 PMCID: PMC6080411 DOI: 10.3389/fncel.2018.00221] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 07/09/2018] [Indexed: 12/28/2022] Open
Abstract
Proper patterning of the nervous system requires that developing axons find appropriate postsynaptic partners; this entails microns to meters of extension through an extracellular milieu exhibiting a wide range of mechanical and chemical properties. Thus, the elaborate networks of fiber tracts and non-fasciculated axons evident in mature organisms are formed via complex pathfinding. The macroscopic structures of axon projections are highly stereotyped across members of the same species, indicating precise mechanisms guide their formation. The developing axon exhibits directionally biased growth toward or away from external guidance cues. One of the most studied guidance cues is netrin-1, however, its presentation in vivo remains debated. Guidance cues can be secreted to form soluble or chemotactic gradients or presented bound to cells or the extracellular matrix to form haptotactic gradients. The growth cone, a highly specialized dynamic structure at the end of the extending axon, detects these guidance cues via transmembrane receptors, such as the netrin-1 receptors deleted in colorectal cancer (DCC) and UNC5. These receptors orchestrate remodeling of the cytoskeleton and cell membrane through both chemical and mechanotransductive pathways, which result in traction forces generated by the cytoskeleton against the extracellular environment and translocation of the growth cone. Through intracellular signaling responses, netrin-1 can trigger either attraction or repulsion of the axon. Here we review the mechanisms by which the classical guidance cue netrin-1 regulates intracellular effectors to respond to the extracellular environment in the context of axon guidance during development of the central nervous system and discuss recent findings that demonstrate the critical importance of mechanical forces in this process.
Collapse
Affiliation(s)
- Nicholas P. Boyer
- Neurobiology Curriculum, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Stephanie L. Gupton
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| |
Collapse
|
164
|
The homeostatic ensemble for cells. Biomech Model Mechanobiol 2018; 17:1631-1662. [PMID: 29987699 DOI: 10.1007/s10237-018-1048-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 06/26/2018] [Indexed: 12/12/2022]
Abstract
Cells are quintessential examples of out-of-equilibrium systems, but they maintain a homeostatic state over a timescale of hours to days. As a consequence, the statistics of all observables is remarkably consistent. Here, we develop a statistical mechanics framework for living cells by including the homeostatic constraint that exists over the interphase period of the cell cycle. The consequence is the introduction of the concept of a homeostatic ensemble and an associated homeostatic temperature, along with a formalism for the (dynamic) homeostatic equilibrium that intervenes to allow living cells to evade thermodynamic decay. As a first application, the framework is shown to accurately predict the observed effect of the mechanical environment on the in vitro response of smooth muscle cells. This includes predictions that both the mean values and diversity/variability in the measured values of observables such as cell area, shape and tractions decrease with decreasing stiffness of the environment. Thus, we argue that the observed variabilities are inherent to the entropic nature of the homeostatic equilibrium of cells and not a result of in vitro experimental errors.
Collapse
|
165
|
Demirörs AF, Akan MT, Poloni E, Studart AR. Active cargo transport with Janus colloidal shuttles using electric and magnetic fields. SOFT MATTER 2018; 14:4741-4749. [PMID: 29799053 DOI: 10.1039/c8sm00513c] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Active colloids show non-equilibrium behavior that departs from classical Brownian motion, thus providing a platform for novel fundamental phenomena and for enticing possible applications ranging from water treatment to medicine and microrobotics. Although the physics, motion mechanisms and guidance have been extensively investigated, active colloids are rarely exploited to simultaneously guide and transport micron-sized objects in a controllable and reversible manner. Here, we use autonomous active Janus particles as colloidal shuttles to controllably transport cargo at the microscale using external electric and magnetic fields. The active motion arises from the metallodielectric characteristics of the Janus particles, which allows them to also trap, transport and release cargo particles through dielectrophoretic interactions induced by an AC electric field. The ferromagnetic nature of the nickel layer that forms the metallic hemisphere of the Janus colloids provides an additional mechanism to direct the motion of the shuttle using an external magnetic field. With this highly programmable colloidal system, we are able to harness active colloid motion and use it to transport cargo particles to specific destinations through a pre-defined route. A simple analytical model is derived to successfully describe the motion of the shuttle-cargo assembly in response to the applied electrical field. The high level of control on cargo pick-up, transport and release leads to a powerful delivery tool, which could eventually be used in microactuators, microfluidics or for controlled delivery within organ-on-a-chip devices.
Collapse
Affiliation(s)
- Ahmet F Demirörs
- Complex Materials, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
| | | | | | | |
Collapse
|
166
|
Extracellular Galectin-3 Induces Accelerated Oligodendroglial Differentiation Through Changes in Signaling Pathways and Cytoskeleton Dynamics. Mol Neurobiol 2018; 56:336-349. [DOI: 10.1007/s12035-018-1089-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 04/16/2018] [Indexed: 02/01/2023]
|
167
|
Unzue A, Cribiú R, Hoffman MM, Knehans T, Lafleur K, Caflisch A, Nevado C. Iriomoteolides: novel chemical tools to study actin dynamics. Chem Sci 2018; 9:3793-3802. [PMID: 29780512 PMCID: PMC5939837 DOI: 10.1039/c7sc04286h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 03/10/2018] [Indexed: 01/25/2023] Open
Abstract
Despite its promising biological profile, the cellular targets of iriomoteolide-3a, a novel 15-membered macrolide isolated from Amphidinium sp., have remained unknown. A small library of non-natural iriomoteolide-3a analogues is presented here as a result of a novel, highly convergent, catalysis-based scaffold-diversification campaign, which revealed the suitable sites for chemical editing in the original core. We provide compelling experimental evidence for actin as one of iriomoteolides' primary cellular targets, establishing the ability of these secondary metabolites to inhibit cell migration, induce severe morphological changes in cells and cause a reversible cytoplasmic retraction and reduction of F-actin fibers in a time and dose dependent manner. These results are interpreted in light of the ability of iriomoteolides to stabilize F-actin filaments. Molecular dynamics simulations provide evidence for iriomoteolide-3a binding to the barbed end of G-actin. These results showcase iriomoteolides as novel and easily tunable chemical probes for the in vitro study of actin dynamics in the context of cell motility processes including cell invasion and division.
Collapse
Affiliation(s)
- A Unzue
- Department of Chemistry , University of Zürich , Winterthurerstrasse 190 , CH-8057 , Zürich , Switzerland .
| | - R Cribiú
- Department of Chemistry , University of Zürich , Winterthurerstrasse 190 , CH-8057 , Zürich , Switzerland .
| | - M M Hoffman
- Department of Chemistry , University of Zürich , Winterthurerstrasse 190 , CH-8057 , Zürich , Switzerland .
| | - T Knehans
- Department of Biochemistry , University of Zürich , Winterthurerstrasse 190 , CH-8057 , Zürich , Switzerland .
| | - K Lafleur
- Department of Chemistry , University of Zürich , Winterthurerstrasse 190 , CH-8057 , Zürich , Switzerland .
| | - A Caflisch
- Department of Biochemistry , University of Zürich , Winterthurerstrasse 190 , CH-8057 , Zürich , Switzerland .
| | - C Nevado
- Department of Chemistry , University of Zürich , Winterthurerstrasse 190 , CH-8057 , Zürich , Switzerland .
| |
Collapse
|
168
|
Huang S, Chi Y, Qin Y, Wang Z, Xiu B, Su Y, Guo R, Guo L, Sun H, Zeng C, Zhou S, Hu X, Liu S, Shao Z, Wu Z, Jin W, Wu J. CAPG enhances breast cancer metastasis by competing with PRMT5 to modulate STC-1 transcription. Theranostics 2018; 8:2549-2564. [PMID: 29721098 PMCID: PMC5928908 DOI: 10.7150/thno.22523] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 02/22/2018] [Indexed: 11/20/2022] Open
Abstract
Macrophage-capping protein (CAPG) has been shown to promote cancer cell metastasis, although the mechanism remains poorly understood. Methods: Breast cancer (BC) tissue microarray was used to test the role of CAPG in the prognosis of BC patients. Xenograft mice model was used to validate the metastasis promotion role of CAPG in vivo. Gene expression array, chromatin immunoprecipitation and luciferase report assay were performed to search for the target genes of CAPG. Protein immunoprecipitation, MS/MS analysis, tissue microarray and histone methyltransferase assay were used to explore the mechanism of CAPG regulating stanniocalcin 1 (STC-1) transcription. Results: We demonstrate a novel mechanism by which CAPG enhances BC metastasis via promoting the transcription of the pro-metastatic gene STC-1, contributing to increased metastasis in BC. Mechanistically, CAPG competes with the transcriptional repressor arginine methyltransferase 5 (PRMT5) for binding to the STC-1 promoter, leading to reduced histone H4R3 methylation and enhanced STC-1 transcription. Our study also indicates that both CAPG and PRMT5 are independent prognostic factors for BC patient survival. High CAPG level is associated with poor survival, while high PRMT5 expression favors a better prognosis in BC patients. Conclusion: Our findings identify a novel role of CAPG in the promotion of BC metastasis by epigenetically enhancing STC-1 transcription.
Collapse
|
169
|
Wu Z, Su M, Tong C, Wu M, Liu J. Membrane shape-mediated wave propagation of cortical protein dynamics. Nat Commun 2018; 9:136. [PMID: 29321558 PMCID: PMC5762918 DOI: 10.1038/s41467-017-02469-1] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 12/01/2017] [Indexed: 11/15/2022] Open
Abstract
Immune cells exhibit stimulation-dependent traveling waves in the cortex, much faster than typical cortical actin waves. These waves reflect rhythmic assembly of both actin machinery and peripheral membrane proteins such as F-BAR domain-containing proteins. Combining theory and experiments, we develop a mechanochemical feedback model involving membrane shape changes and F-BAR proteins that render the cortex an interesting dynamical system. We show that such cortical dynamics manifests itself as ultrafast traveling waves of cortical proteins, in which the curvature sensitivity-driven feedback always constrains protein lateral diffusion in wave propagation. The resulting protein wave propagation mainly reflects the spatial gradient in the timing of local protein recruitment from cytoplasm. We provide evidence that membrane undulations accompany these protein waves and potentiate their propagation. Therefore, membrane shape change and protein curvature sensitivity may have underappreciated roles in setting high-speed cortical signal transduction rhythms. Traveling waves in the cell cortex can propagate much faster than actin waves, and the mechanism is unknown. Here the authors propose a mechanochemical feedback model for traveling waves that incorporates membrane shape changes and recruitment of F-BAR proteins that enables fast wave propagation.
Collapse
Affiliation(s)
- Zhanghan Wu
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Maohan Su
- Department of Biological Sciences, Centre for Bioimaging Sciences, Mechanobiology Institute, National University of Singapore, Singapore, 117557, Singapore
| | - Cheesan Tong
- Department of Biological Sciences, Centre for Bioimaging Sciences, Mechanobiology Institute, National University of Singapore, Singapore, 117557, Singapore
| | - Min Wu
- Department of Biological Sciences, Centre for Bioimaging Sciences, Mechanobiology Institute, National University of Singapore, Singapore, 117557, Singapore.
| | - Jian Liu
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| |
Collapse
|
170
|
Skruber K, Read TA, Vitriol EA. Reconsidering an active role for G-actin in cytoskeletal regulation. J Cell Sci 2018; 131:131/1/jcs203760. [PMID: 29321224 DOI: 10.1242/jcs.203760] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Globular (G)-actin, the actin monomer, assembles into polarized filaments that form networks that can provide structural support, generate force and organize the cell. Many of these structures are highly dynamic and to maintain them, the cell relies on a large reserve of monomers. Classically, the G-actin pool has been thought of as homogenous. However, recent work has shown that actin monomers can exist in distinct groups that can be targeted to specific networks, where they drive and modify filament assembly in ways that can have profound effects on cellular behavior. This Review focuses on the potential factors that could create functionally distinct pools of actin monomers in the cell, including differences between the actin isoforms and the regulation of G-actin by monomer binding proteins, such as profilin and thymosin β4. Owing to difficulties in studying and visualizing G-actin, our knowledge over the precise role that specific actin monomer pools play in regulating cellular actin dynamics remains incomplete. Here, we discuss some of these unanswered questions and also provide a summary of the methodologies currently available for the imaging of G-actin.
Collapse
Affiliation(s)
- Kristen Skruber
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
| | - Tracy-Ann Read
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
| | - Eric A Vitriol
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
| |
Collapse
|
171
|
Li Y, Ji S, Fu L, Jiang T, Wu D, Meng F. Over-expression of ARHGAP18 suppressed cell proliferation, migration, invasion, and tumor growth in gastric cancer by restraining over-activation of MAPK signaling pathways. Onco Targets Ther 2018; 11:279-290. [PMID: 29386906 PMCID: PMC5767098 DOI: 10.2147/ott.s130255] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Globally, gastric cancer is the second-greatest cause of cancer death. ARHGAP18 belongs to the Rho family of GTPases which is involved in cellular migration, invasion, and growth phases. The aim of the present study was to investigate whether ARHGAP18 could regulate cell proliferation, migration, invasion, and related molecular mechanisms in gastric cancer. Cell Counting Kit-8 (CCK-8) assay results showed that following transfection of a recombinant plasmid, over-expression of ARHGAP18 inhibited cell viability in MGC-803 and BGC823 cells. Using in vitro transwell analysis, migration and invasion abilities were significantly inhibited in cells with high ARHGAP18 expression. Phosphorylation levels of ERK, JNK, and p38 by Western blot analysis significantly declined after transfection of cells with the ARHGAP18 plasmid. Expression levels of ROCK, MTA1, and MMP-2/9 were detected by real-time polymerase chain reaction and Western blotting, and over-expression of ARHGAP18 decreased the expression levels of ROCK, MTA1, and MMP-9. A further in vivo tumor formation study in nude mice indicated that over-expression of ARHGAP18 delayed the progress of tumor formation. These results indicate that ARHGAP18 could act as a tumor suppressor and may serve as a promising therapeutic strategy for gastric cancer.
Collapse
Affiliation(s)
- Yan Li
- Department of Biotherapy, Cancer Research Institute, the First Affiliated Hospital of China Medical University, Shenyang City, People's Republic of China
| | - Shan Ji
- Department of Endocrinology, The Fifth People's Hospital of Shenyang City, Shenyang City, People's Republic of China
| | - Liye Fu
- Department of Biotherapy, Cancer Research Institute, the First Affiliated Hospital of China Medical University, Shenyang City, People's Republic of China
| | - Tao Jiang
- Department of Biotherapy, Cancer Research Institute, the First Affiliated Hospital of China Medical University, Shenyang City, People's Republic of China
| | - Di Wu
- Department of Biotherapy, Cancer Research Institute, the First Affiliated Hospital of China Medical University, Shenyang City, People's Republic of China
| | - Fandong Meng
- Department of Biotherapy, Cancer Research Institute, the First Affiliated Hospital of China Medical University, Shenyang City, People's Republic of China
| |
Collapse
|
172
|
Design of Fiber Networks for Studying Metastatic Invasion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1092:289-318. [DOI: 10.1007/978-3-319-95294-9_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
173
|
Radeva MY, Waschke J. Mind the gap: mechanisms regulating the endothelial barrier. Acta Physiol (Oxf) 2018; 222. [PMID: 28231640 DOI: 10.1111/apha.12860] [Citation(s) in RCA: 161] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/21/2016] [Accepted: 02/16/2017] [Indexed: 12/11/2022]
Abstract
The endothelial barrier consists of intercellular contacts localized in the cleft between endothelial cells, which is covered by the glycocalyx in a sievelike manner. Both types of barrier-forming junctions, i.e. the adherens junction (AJ) serving mechanical anchorage and mechanotransduction and the tight junction (TJ) sealing the intercellular space to limit paracellular permeability, are tethered to the actin cytoskeleton. Under resting conditions, the endothelium thereby builds a selective layer controlling the exchange of fluid and solutes with the surrounding tissue. However, in the situation of an inflammatory response such as in anaphylaxis or sepsis intercellular contacts disintegrate in post-capillary venules leading to intercellular gap formation. The resulting oedema can cause shock and multi-organ failure. Therefore, maintenance as well as coordinated opening and closure of interendothelial junctions is tightly regulated. The two principle underlying mechanisms comprise spatiotemporal activity control of the small GTPases Rac1 and RhoA and the balance of the phosphorylation state of AJ proteins. In the resting state, junctional Rac1 and RhoA activity is enhanced by junctional components, actin-binding proteins, cAMP signalling and extracellular cues such as sphingosine-1-phosphate (S1P) and angiopoietin-1 (Ang-1). In addition, phosphorylation of AJ components is prevented by junction-associated phosphatases including vascular endothelial protein tyrosine phosphatase (VE-PTP). In contrast, inflammatory mediators inhibiting cAMP/Rac1 signalling cause strong activation of RhoA and induce AJ phosphorylation finally leading to endocytosis and cleavage of VE-cadherin. This results in dissolution of TJs the outcome of which is endothelial barrier breakdown.
Collapse
Affiliation(s)
- M. Y. Radeva
- Institute of Anatomy and Cell Biology; Ludwig-Maximilians-Universität München; Munich Germany
| | - J. Waschke
- Institute of Anatomy and Cell Biology; Ludwig-Maximilians-Universität München; Munich Germany
| |
Collapse
|
174
|
Functional Analysis of Human Hub Proteins and Their Interactors Involved in the Intrinsic Disorder-Enriched Interactions. Int J Mol Sci 2017; 18:ijms18122761. [PMID: 29257115 PMCID: PMC5751360 DOI: 10.3390/ijms18122761] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/13/2017] [Accepted: 12/15/2017] [Indexed: 12/15/2022] Open
Abstract
Some of the intrinsically disordered proteins and protein regions are promiscuous interactors that are involved in one-to-many and many-to-one binding. Several studies have analyzed enrichment of intrinsic disorder among the promiscuous hub proteins. We extended these works by providing a detailed functional characterization of the disorder-enriched hub protein-protein interactions (PPIs), including both hubs and their interactors, and by analyzing their enrichment among disease-associated proteins. We focused on the human interactome, given its high degree of completeness and relevance to the analysis of the disease-linked proteins. We quantified and investigated numerous functional and structural characteristics of the disorder-enriched hub PPIs, including protein binding, structural stability, evolutionary conservation, several categories of functional sites, and presence of over twenty types of posttranslational modifications (PTMs). We showed that the disorder-enriched hub PPIs have a significantly enlarged number of disordered protein binding regions and long intrinsically disordered regions. They also include high numbers of targeting, catalytic, and many types of PTM sites. We empirically demonstrated that these hub PPIs are significantly enriched among 11 out of 18 considered classes of human diseases that are associated with at least 100 human proteins. Finally, we also illustrated how over a dozen specific human hubs utilize intrinsic disorder for their promiscuous PPIs.
Collapse
|
175
|
ExoY, an actin-activated nucleotidyl cyclase toxin from P. aeruginosa: A minireview. Toxicon 2017; 149:65-71. [PMID: 29258848 DOI: 10.1016/j.toxicon.2017.12.046] [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] [Received: 10/02/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 11/23/2022]
Abstract
ExoY is one of four well-characterized Pseudomonas aeruginosa type 3 secretion system (T3SS) effectors. It is a nucleotidyl cyclase toxin that is inactive inside the bacteria, but becomes potently activated once it is delivered into the eukaryotic target cells. Recently, filamentous actin was identified as the eukaryotic cofactor that stimulates specifically ExoY enzymatic activity by several orders of magnitude. In this review, we discuss recent advances in understanding the biochemistry of nucleotidyl cyclase activity of ExoY and its regulation by interaction with filamentous actin.
Collapse
|
176
|
Ryan GL, Holz D, Yamashiro S, Taniguchi D, Watanabe N, Vavylonis D. Cell protrusion and retraction driven by fluctuations in actin polymerization: A two-dimensional model. Cytoskeleton (Hoboken) 2017; 74:490-503. [PMID: 28752950 PMCID: PMC5725282 DOI: 10.1002/cm.21389] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 07/19/2017] [Accepted: 07/24/2017] [Indexed: 12/23/2022]
Abstract
Animal cells that spread onto a surface often rely on actin-rich lamellipodial extensions to execute protrusion. Many cell types recently adhered on a two-dimensional substrate exhibit protrusion and retraction of their lamellipodia, even though the cell is not translating. Travelling waves of protrusion have also been observed, similar to those observed in crawling cells. These regular patterns of protrusion and retraction allow quantitative analysis for comparison to mathematical models. The periodic fluctuations in leading edge position of XTC cells have been linked to excitable actin dynamics using a one-dimensional model of actin dynamics, as a function of arc-length along the cell. In this work we extend this earlier model of actin dynamics into two dimensions (along the arc-length and radial directions of the cell) and include a model membrane that protrudes and retracts in response to the changing number of free barbed ends of actin filaments near the membrane. We show that if the polymerization rate at the barbed ends changes in response to changes in their local concentration at the leading edge and/or the opposing force from the cell membrane, the model can reproduce the patterns of membrane protrusion and retraction seen in experiment. We investigate both Brownian ratchet and switch-like force-velocity relationships between the membrane load forces and actin polymerization rate. The switch-like polymerization dynamics recover the observed patterns of protrusion and retraction as well as the fluctuations in F-actin concentration profiles. The model generates predictions for the behavior of cells after local membrane tension perturbations.
Collapse
Affiliation(s)
- Gillian L. Ryan
- Department of Physics, Kettering University, 1700 University Avenue, Flint MI 48504, United States
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem PA 18105, United States
| | - Danielle Holz
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem PA 18105, United States
| | - Sawako Yamashiro
- Department of Pharmacology, Kyoto University Faculty of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Daisuke Taniguchi
- Department of Pharmacology, Kyoto University Faculty of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Naoki Watanabe
- Department of Pharmacology, Kyoto University Faculty of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Dimitrios Vavylonis
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem PA 18105, United States
| |
Collapse
|
177
|
Zhu L, Yang J, Bromberger T, Holly A, Lu F, Liu H, Sun K, Klapproth S, Hirbawi J, Byzova TV, Plow EF, Moser M, Qin J. Structure of Rap1b bound to talin reveals a pathway for triggering integrin activation. Nat Commun 2017; 8:1744. [PMID: 29170462 PMCID: PMC5701058 DOI: 10.1038/s41467-017-01822-8] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 10/18/2017] [Indexed: 11/17/2022] Open
Abstract
Activation of transmembrane receptor integrin by talin is essential for inducing cell adhesion. However, the pathway that recruits talin to the membrane, which critically controls talin's action, remains elusive. Membrane-anchored mammalian small GTPase Rap1 is known to bind talin-F0 domain but the binding was shown to be weak and thus hardly studied. Here we show structurally that talin-F0 binds to human Rap1b like canonical Rap1 effectors despite little sequence homology, and disruption of the binding strongly impairs integrin activation, cell adhesion, and cell spreading. Furthermore, while being weak in conventional binary binding conditions, the Rap1b/talin interaction becomes strong upon attachment of activated Rap1b to vesicular membranes that mimic the agonist-induced microenvironment. These data identify a crucial Rap1-mediated membrane-targeting mechanism for talin to activate integrin. They further broadly caution the analyses of weak protein-protein interactions that may be pivotal for function but neglected in the absence of specific cellular microenvironments.
Collapse
Affiliation(s)
- Liang Zhu
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Jun Yang
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Thomas Bromberger
- Max-Planck-Institute of Biochemistry, Department of Molecular Medicine, 82152, Martinsried, Germany
| | - Ashley Holly
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Fan Lu
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Huan Liu
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Kevin Sun
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Sarah Klapproth
- Max-Planck-Institute of Biochemistry, Department of Molecular Medicine, 82152, Martinsried, Germany
| | - Jamila Hirbawi
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Tatiana V Byzova
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Edward F Plow
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Markus Moser
- Max-Planck-Institute of Biochemistry, Department of Molecular Medicine, 82152, Martinsried, Germany.
| | - Jun Qin
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, 44106, USA.
| |
Collapse
|
178
|
Henty-Ridilla JL, Juanes MA, Goode BL. Profilin Directly Promotes Microtubule Growth through Residues Mutated in Amyotrophic Lateral Sclerosis. Curr Biol 2017; 27:3535-3543.e4. [PMID: 29129529 PMCID: PMC5772683 DOI: 10.1016/j.cub.2017.10.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/31/2017] [Accepted: 10/02/2017] [Indexed: 12/11/2022]
Abstract
Profilin is an abundant actin monomer-binding protein with critical actin regulatory roles in vivo [1, 2]. However, profilin also influences microtubule dynamics in cells, which may be mediated in part through its interactions with formins that in turn bind microtubules [3, 4]. Specific residues on human profilin-1 (PFN1) are mutated in patients with amyotrophic lateral sclerosis (ALS) [5, 6]. However, the observation that some ALS-linked PFN1 mutants fail to alter cellular actin organization or dynamics [5-8] or in vitro actin-monomer affinity [9] has been perplexing, given that profilin is best understood as an actin regulator. Here, we investigated direct effects of profilin on microtubule dynamics and whether ALS-linked mutations in PFN1 disrupt such functions. We found that human, fly, and yeast profilin homologs all directly enhance microtubule growth rate by several-fold in vitro. Microtubule stimulatory effects were unaffected by mutations in the canonical actin- or poly-proline-binding sites of profilin. Instead, microtubule activities depended on specific surface residues on profilin mutated in ALS patients. Furthermore, microtubule effects were attenuated by increasing concentrations of actin monomers, suggesting competition between actin and microtubules for binding profilin. Consistent with these biochemical observations, a 2-fold increase in the expression level of wild-type PFN1, but not the ALS-linked PFN1 mutants, increased microtubule growth rates in cells. Together, these results demonstrate that profilin directly enhances the growth rate of microtubules. They further suggest that ALS-linked mutations in PFN1 may perturb cellular microtubule dynamics and/or the coordination between the actin and microtubule cytoskeletons, leading to motor neuron degeneration.
Collapse
Affiliation(s)
| | - M Angeles Juanes
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Bruce L Goode
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
| |
Collapse
|
179
|
Bieling P, Hansen SD, Akin O, Li TD, Hayden CC, Fletcher DA, Mullins RD. WH2 and proline-rich domains of WASP-family proteins collaborate to accelerate actin filament elongation. EMBO J 2017; 37:102-121. [PMID: 29141912 PMCID: PMC5753033 DOI: 10.15252/embj.201797039] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 02/04/2023] Open
Abstract
WASP‐family proteins are known to promote assembly of branched actin networks by stimulating the filament‐nucleating activity of the Arp2/3 complex. Here, we show that WASP‐family proteins also function as polymerases that accelerate elongation of uncapped actin filaments. When clustered on a surface, WASP‐family proteins can drive branched actin networks to grow much faster than they could by direct incorporation of soluble monomers. This polymerase activity arises from the coordinated action of two regulatory sequences: (i) a WASP homology 2 (WH2) domain that binds actin, and (ii) a proline‐rich sequence that binds profilin–actin complexes. In the absence of profilin, WH2 domains are sufficient to accelerate filament elongation, but in the presence of profilin, proline‐rich sequences are required to support polymerase activity by (i) bringing polymerization‐competent actin monomers in proximity to growing filament ends, and (ii) promoting shuttling of actin monomers from profilin–actin complexes onto nearby WH2 domains. Unoccupied WH2 domains transiently associate with free filament ends, preventing their growth and dynamically tethering the branched actin network to the WASP‐family proteins that create it. Collaboration between WH2 and proline‐rich sequences thus strikes a balance between filament growth and tethering. Our work expands the number of critical roles that WASP‐family proteins play in the assembly of branched actin networks to at least three: (i) promoting dendritic nucleation; (ii) linking actin networks to membranes; and (iii) accelerating filament elongation.
Collapse
Affiliation(s)
- Peter Bieling
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA, USA .,Department of Bioengineering & Biophysics Program, University of California, Berkeley, CA, USA.,Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Scott D Hansen
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA, USA
| | - Orkun Akin
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA, USA
| | - Tai-De Li
- Department of Bioengineering & Biophysics Program, University of California, Berkeley, CA, USA.,Chan Zuckerberg Biohub, San Francisco, CA, USA.,Biological Systems & Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Daniel A Fletcher
- Department of Bioengineering & Biophysics Program, University of California, Berkeley, CA, USA .,Chan Zuckerberg Biohub, San Francisco, CA, USA.,Biological Systems & Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - R Dyche Mullins
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA, USA
| |
Collapse
|
180
|
Breitbart H, Finkelstein M. Actin cytoskeleton and sperm function. Biochem Biophys Res Commun 2017; 506:372-377. [PMID: 29102633 DOI: 10.1016/j.bbrc.2017.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 11/01/2017] [Indexed: 11/17/2022]
Abstract
For the acquisition of the ability to fertilize the egg, mammalian spermatozoa should undergo a series of biochemical transformations in the female reproductive tract, collectively called capacitation. The capacitated sperm can undergo the acrosomal exocytosis process near or on the oocyte, which allows the spermatozoon to penetrate and fertilize it. One of the main processes in capacitation involves dynamic cytoskeletal remodeling particularly of actin. Actin polymerization occurs during sperm capacitation and the produced F-actin should be depolymerized prior to the acrosomal exocytosis. In the present review, we describe the mechanisms that regulate F-actin formation during sperm capacitation and the F-actin dispersion prior to the acrosomal exocytosis. During sperm capacitation, the actin severing proteins gelsolin and cofilin are inactive and they undergo activation prior to the acrosomal exocytosis.
Collapse
Affiliation(s)
- Haim Breitbart
- The Mina & Everard Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel.
| | | |
Collapse
|
181
|
Abstract
Despite their fundamental importance in the regulation of cell physiology, the mechanisms that confer cell adaptability to changes in the microenvironment are poorly understood. A recent study in Cell (Mueller et al., 2017) examines the capability of branched actin networks to respond and adapt to mechanical load in vivo.
Collapse
Affiliation(s)
- Julie Plastino
- Institut Curie, PSL Research University, CNRS, UMR 168, 75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 168, 75005 Paris, France.
| | - Laurent Blanchoin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054 Grenoble, France; CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, 75010 Paris, France.
| |
Collapse
|
182
|
Kawai S, Araki S, Kodama Y. No mutual symbiosis following infection of algae-free Paramecium bursaria with symbiotic algae from Mayorella viridis. Symbiosis 2017. [DOI: 10.1007/s13199-017-0517-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
183
|
Hsu HF, Bodenschatz E, Westendorf C, Gholami A, Pumir A, Tarantola M, Beta C. Variability and Order in Cytoskeletal Dynamics of Motile Amoeboid Cells. PHYSICAL REVIEW LETTERS 2017; 119:148101. [PMID: 29053324 DOI: 10.1103/physrevlett.119.148101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Indexed: 06/07/2023]
Abstract
The chemotactic motion of eukaryotic cells such as leukocytes or metastatic cancer cells relies on membrane protrusions driven by the polymerization and depolymerization of actin. Here we show that the response of the actin system to a receptor stimulus is subject to a threshold value that varies strongly from cell to cell. Above the threshold, we observe pronounced cell-to-cell variability in the response amplitude. The polymerization time, however, is almost constant over the entire range of response amplitudes, while the depolymerization time increases with increasing amplitude. We show that cell-to-cell variability in the response amplitude correlates with the amount of Arp2/3, a protein that enhances actin polymerization. A time-delayed feedback model for the cortical actin concentration is consistent with all our observations and confirms the role of Arp2/3 in the observed cell-to-cell variability. Taken together, our observations highlight robust regulation of the actin response that enables a reliable timing of cell movement.
Collapse
Affiliation(s)
- Hsin-Fang Hsu
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
| | - Eberhard Bodenschatz
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
- Institute for Nonlinear Dynamics, University of Göttingen, D-37073 Göttingen, Germany
- Laboratory of Atomic and Solid-State Physics and Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Christian Westendorf
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
| | - Azam Gholami
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
| | - Alain Pumir
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
- Université Lyon, ENS de Lyon, Université Claude Bernard, CNRS, Laboratoire de Physique, F-69342 Lyon, France
| | - Marco Tarantola
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
| | - Carsten Beta
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
- Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam, Germany
| |
Collapse
|
184
|
Swaminathan V, Kalappurakkal JM, Mehta SB, Nordenfelt P, Moore TI, Koga N, Baker DA, Oldenbourg R, Tani T, Mayor S, Springer TA, Waterman CM. Actin retrograde flow actively aligns and orients ligand-engaged integrins in focal adhesions. Proc Natl Acad Sci U S A 2017; 114:10648-10653. [PMID: 29073038 PMCID: PMC5635867 DOI: 10.1073/pnas.1701136114] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Integrins are transmembrane receptors that, upon activation, bind extracellular ligands and link them to the actin filament (F-actin) cytoskeleton to mediate cell adhesion and migration. Cytoskeletal forces in migrating cells generated by polymerization- or contractility-driven "retrograde flow" of F-actin from the cell leading edge have been hypothesized to mediate integrin activation for ligand binding. This predicts that these forces should align and orient activated, ligand-bound integrins at the leading edge. Here, polarization-sensitive fluorescence microscopy of GFP-αVβ3 integrins in fibroblasts shows that integrins are coaligned in a specific orientation within focal adhesions (FAs) in a manner dependent on binding immobilized ligand and a talin-mediated linkage to the F-actin cytoskeleton. These findings, together with Rosetta modeling, suggest that integrins in FA are coaligned and may be highly tilted by cytoskeletal forces. Thus, the F-actin cytoskeleton sculpts an anisotropic molecular scaffold in FAs, and this feature may underlie the ability of migrating cells to sense directional extracellular cues.
Collapse
Affiliation(s)
- Vinay Swaminathan
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Physiology Course, Marine Biological Laboratory, Woods Hole, MA 02543
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20892
| | - Joseph Mathew Kalappurakkal
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Physiology Course, Marine Biological Laboratory, Woods Hole, MA 02543
- National Centre for Biological Sciences, Bangalore 560065, Karnataka, India
| | - Shalin B Mehta
- Eugene Bell Center, Marine Biological Laboratory, Woods Hole, MA 02543
| | - Pontus Nordenfelt
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Physiology Course, Marine Biological Laboratory, Woods Hole, MA 02543
- Division of Infection Medicine, Lund University, SE-221 84 Lund, Sweden
- Program in Cellular and Molecular Medicine, Children's Hospital, Boston, MA 02115
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Travis I Moore
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Program in Cellular and Molecular Medicine, Children's Hospital, Boston, MA 02115
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Nobuyasu Koga
- Department of Biochemistry, University of Washington, Seattle, WA 98195
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195
- Institute for Molecular Science, Okazaki 444-8585, Japan
| | - David A Baker
- Department of Biochemistry, University of Washington, Seattle, WA 98195
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195
| | - Rudolf Oldenbourg
- Eugene Bell Center, Marine Biological Laboratory, Woods Hole, MA 02543
| | - Tomomi Tani
- Eugene Bell Center, Marine Biological Laboratory, Woods Hole, MA 02543
| | - Satyajit Mayor
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Physiology Course, Marine Biological Laboratory, Woods Hole, MA 02543
- National Centre for Biological Sciences, Bangalore 560065, Karnataka, India
| | - Timothy A Springer
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Program in Cellular and Molecular Medicine, Children's Hospital, Boston, MA 02115
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Clare M Waterman
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543;
- Physiology Course, Marine Biological Laboratory, Woods Hole, MA 02543
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20892
| |
Collapse
|
185
|
Raz-Ben Aroush D, Ofer N, Abu-Shah E, Allard J, Krichevsky O, Mogilner A, Keren K. Actin Turnover in Lamellipodial Fragments. Curr Biol 2017; 27:2963-2973.e14. [PMID: 28966086 DOI: 10.1016/j.cub.2017.08.066] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 07/21/2017] [Accepted: 08/29/2017] [Indexed: 10/18/2022]
Abstract
Actin turnover is the central driving force underlying lamellipodial motility. The molecular components involved are largely known, and their properties have been studied extensively in vitro. However, a comprehensive picture of actin turnover in vivo is still missing. We focus on fragments from fish epithelial keratocytes, which are essentially stand-alone motile lamellipodia. The geometric simplicity of the fragments and the absence of additional actin structures allow us to characterize the spatiotemporal lamellipodial actin organization with unprecedented detail. We use fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, and extraction experiments to show that about two-thirds of the lamellipodial actin diffuses in the cytoplasm with nearly uniform density, whereas the rest forms the treadmilling polymer network. Roughly a quarter of the diffusible actin pool is in filamentous form as diffusing oligomers, indicating that severing and debranching are important steps in the disassembly process generating oligomers as intermediates. The remaining diffusible actin concentration is orders of magnitude higher than the in vitro actin monomer concentration required to support the observed polymerization rates, implying that the majority of monomers are transiently kept in a non-polymerizable "reserve" pool. The actin network disassembles and reassembles throughout the lamellipodium within seconds, so the lamellipodial network turnover is local. The diffusible actin transport, on the other hand, is global: actin subunits typically diffuse across the entire lamellipodium before reassembling into the network. This combination of local network turnover and global transport of dissociated subunits through the cytoplasm makes actin transport robust yet rapidly adaptable and amenable to regulation.
Collapse
Affiliation(s)
- Dikla Raz-Ben Aroush
- Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Noa Ofer
- Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel; Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Enas Abu-Shah
- Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel; Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Jun Allard
- Department of Mathematics, Center for Complex Biological Systems and Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA
| | - Oleg Krichevsky
- Physics Department and Ilse Kats Center for Nanoscience, Ben-Gurion University, Beer-Sheva 84105, Israel
| | - 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; Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel; Network Biology Research Laboratories, Technion-Israel Institute of Technology, Haifa 32000, Israel.
| |
Collapse
|
186
|
Li Z, Jiao Y, Fan EK, Scott MJ, Li Y, Li S, Billiar TR, Wilson MA, Shi X, Fan J. Aging-Impaired Filamentous Actin Polymerization Signaling Reduces Alveolar Macrophage Phagocytosis of Bacteria. THE JOURNAL OF IMMUNOLOGY 2017; 199:3176-3186. [PMID: 28947541 DOI: 10.4049/jimmunol.1700140] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 08/26/2017] [Indexed: 12/14/2022]
Abstract
In elderly patients, bacterial infection often causes severe complications and sepsis. Compared to younger patients, older patients are more susceptible to sepsis caused by respiratory infection. Macrophage (Mϕ) phagocytosis of bacteria plays a critical role in the clearance of pathogens and the initiation of immune responses. It has been suggested that Mϕ exhibit age-related functional alterations, including reduced chemotaxis, phagocytosis, antibacterial defense, and the ability to generate reactive oxygen species. However, the mechanisms behind these changes remain unclear. The present study sought to determine changes in bacterial phagocytosis in aging alveolar Mϕ (AMϕ) and the underlying mechanisms. We show that bacteria initiate cytoskeleton remodeling in AMϕ through interaction with macrophage receptor with collagenous structure (MARCO), a bacterial scavenger receptor. This remodeling, in turn, promotes enhanced cell surface expression of MARCO and bacterial phagocytosis. We further demonstrate that Rac1-GTP mediates MARCO signaling and activates actin-related protein-2/3 complex, an F-actin nucleator, thereby inducing F-actin polymerization, filopodia formation, and increased cell surface expression of MARCO, all of which are essential for the execution of bacteria phagocytosis. However, AMϕ isolated from aging mice exhibit suppressed Rac1 mRNA and protein expression, which resulted in decreases in Rac1-GTP levels and actin-related protein-2/3 activation, as well as subsequent attenuation of F-actin polymerization, filopodia formation, and cell surface expression of MARCO. As a result, bacterial phagocytosis in aging AMϕ is decreased. This study highlights a previously unidentified mechanism by which aging impairs Mϕ phagocytosis of bacteria. Targeting these pathways may improve outcomes of bacterial infection in elderly patients.
Collapse
Affiliation(s)
- Zhigang Li
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213.,Research and Development, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA 15240
| | - Yang Jiao
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213.,Department of Anesthesiology, Shanghai Xinhua Hospital, Jiaotong University School of Medicine, Shanghai 200092, China
| | - Erica K Fan
- University of Pittsburgh School of Arts and Science, Pittsburgh, PA 15213
| | - Melanie J Scott
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
| | - Yuehua Li
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213.,Research and Development, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA 15240
| | - Song Li
- Center for Pharmacogenetics, Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA 15261; and
| | - Timothy R Billiar
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213.,McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219
| | - Mark A Wilson
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213.,Research and Development, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA 15240
| | - Xueyin Shi
- Department of Anesthesiology, Shanghai Xinhua Hospital, Jiaotong University School of Medicine, Shanghai 200092, China;
| | - Jie Fan
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213; .,Research and Development, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA 15240.,McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219
| |
Collapse
|
187
|
He SW, Xu BH, Liu Y, Wang YL, Chen MH, Xu L, Liao BQ, Lui R, Li FP, Lin YH, Fu XP, Fu BB, Hong ZW, Liu YX, Qi ZQ, Wang HL. SKAP2 regulates Arp2/3 complex for actin-mediated asymmetric cytokinesis by interacting with WAVE2 in mouse oocytes. Cell Cycle 2017; 16:2272-2281. [PMID: 28933599 PMCID: PMC5788478 DOI: 10.1080/15384101.2017.1380126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
SKAP2 (Src kinase-associated phosphoprotein 2), a substrate of Src family kinases, has been suggested to be involved in actin-mediated cellular processes. However, little is known about its role in mouse oocyte maturation. In this study, we thus investigated the expression, localization, and functions of SKAP2 during mouse oocyte asymmetric division. SKAP2 protein expression was detected at all developmental stages in mouse oocytes. Immunofluorescent staining showed that SKAP2 was mainly distributed at the cortex of the oocytes during maturation. Treatment with cytochalasin B in oocytes confirmed that SKAP2 was co-localized with actin. Depletion of SKAP2 by injection with specific short interfering RNA caused failure of spindle migration, polar body extrusion, and cytokinesis defects. Meanwhile, the staining of actin filaments at the oocyte membrane and in the cytoplasm was significantly reduced after these treatments. SKAP2 depletion also disrupted actin cap and cortical granule-free domain formation, and arrested a large proportion of oocytes at the telophase stage. Moreover, Arp2/3 complex and WAVE2 expression was decreased after the depletion of SKAP2 activity. Our results indicate that SKAP2 regulates the Arp2/3 complex and is essential for actin-mediated asymmetric cytokinesis by interacting with WAVE2 in mouse oocytes.
Collapse
Affiliation(s)
- Shu-Wen He
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Bai-Hui Xu
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,g Department of Workshop 25, Shangdong new time Pharmaceutical Company Limited , Shangdong , China
| | - Yu Liu
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Ya-Long Wang
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Ming-Huang Chen
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China.,c Department of Gynaecology and Obstetrics , Zhongshan Hospital , Xiamen, Fujian , China
| | - Lin Xu
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Bao-Qiong Liao
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Rui Lui
- c Department of Gynaecology and Obstetrics , Zhongshan Hospital , Xiamen, Fujian , China.,d Department of Gynaecology and Obstetrics , Zhongxin Hospital , Qingdao, Shangdong , China
| | - Fei-Ping Li
- b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China.,f Department of Life Science, Biological College, Southwest Forestry University , Kunming , China
| | - Yan-Hong Lin
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,e Department of Gynaecology and Obstetrics , the First Clinical Medical College, Fujian Medical University , Fuzhou , China
| | - Xian-Pei Fu
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Bin-Bin Fu
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Zi-Wei Hong
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Yu-Xin Liu
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Zhong-Quan Qi
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| | - Hai-Long Wang
- a Organ Transplantation Institute, Medical College, Xiamen University , Xiamen, Fujian , China.,b Fujian Key Laboratory of Organ and Tissue Regeneration , Xiamen, Fujian , China
| |
Collapse
|
188
|
Boujemaa-Paterski R, Suarez C, Klar T, Zhu J, Guérin C, Mogilner A, Théry M, Blanchoin L. Network heterogeneity regulates steering in actin-based motility. Nat Commun 2017; 8:655. [PMID: 28935896 PMCID: PMC5608943 DOI: 10.1038/s41467-017-00455-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 06/29/2017] [Indexed: 11/10/2022] Open
Abstract
The growth of branched actin networks powers cell-edge protrusions and motility. A heterogeneous density of actin, which yields to a tunable cellular response, characterizes these dynamic structures. We study how actin organization controls both the rate and the steering during lamellipodium growth. We use a high-resolution surface structuration assay combined with mathematical modeling to describe the growth of a reconstituted lamellipodium. We demonstrate that local monomer depletion at the site of assembly negatively impacts the network growth rate. At the same time, network architecture tunes the protrusion efficiency, and regulates the rate of growth. One consequence of this interdependence between monomer depletion and network architecture effects is the ability of heterogeneous network to impose steering during motility. Therefore, we have established that the general principle, by which the cell can modulate the rate and the direction of a protrusion, is by varying both density and architecture of its actin network. Protrusive cellular structures contain a heterogeneous density of actin, but whether this influences motility is not known. Using an in vitro system and modelling, here the authors show that local actin monomer depletion and network architecture can tune the rate of network growth to impose steering during motility.
Collapse
Affiliation(s)
- Rajaa Boujemaa-Paterski
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France
| | - Cristian Suarez
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France
| | - Tobias Klar
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France
| | - Jie Zhu
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York, NY, 10012, USA
| | - Christophe Guérin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York, NY, 10012, USA.
| | - Manuel Théry
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France. .,CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, 75010, Paris, France.
| | - Laurent Blanchoin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France. .,CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, 75010, Paris, France.
| |
Collapse
|
189
|
Ahn CS, Kim JG, Bae YA, Kim SH, Shin JH, Yang Y, Kang I, Kong Y. Fasciclin-calcareous corpuscle binary complex mediated protein-protein interactions in Taenia solium metacestode. Parasit Vectors 2017; 10:438. [PMID: 28931431 PMCID: PMC5606126 DOI: 10.1186/s13071-017-2359-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 08/31/2017] [Indexed: 01/30/2023] Open
Abstract
Background Neurocysticercosis (NC) caused by Taenia solium metacestode (TsM) is a serious neurological disease of global concern. Diverse bioactive molecules involved in the long-term survival of TsM might contribute to disease progression. Fasciclin (Fas) is an extracellular protein that mediates adhesion, migration and differentiation of cells by interacting with other molecules. We hypothesized that TsMFas might bind to calcareous corpuscle (CC) through its adhesive property and participate in crucial protein-protein interactions, thus contributing to the creation of a symbiotic interactome network. Methods Two paralogous TsMFas (TsMFas1 and TsMFas2) were isolated, and their molecular properties were characterized. The co-localization pattern of TsMFas1 and TsMFas2 with CC was determined. CC-TsMFas binary complex was generated by incubating CC with recombinant proteins (rTsMFas1 and 2). In vitro binding assay of CC-rTsMFas1 or CC-rTsMFas2 binary complex with TsM cellular proteins extracted from scolex and neck was conducted. Their binding partners were identified through proteomic analysis. Integrated protein-protein interaction networks were established. Results TsMFas1 (6072 bp long) was composed of 15 exons (841 amino acid polypeptide) interrupted by 14 introns. TsMFas2 (5201 bp long) comprised of 11 exons (597 amino acids) and 10 intervening introns. These proteins displayed 22% amino acid sequence identity to each other, but tightly conserved Fas-related domains. Several isoforms of Fas1 and Fas2 proteins might have been expressed through post-translational modifications. They showed adhesion activity with other cells. TsMFas proteins were largely distributed in parenchymal regions of the scolex and bladder wall. These molecules were co-localized with CC, a unique organelle found in platyhelminths. Subsequent proteome analysis of CC-Fas binary complex mediated protein-protein interactions revealed seven protein ligands in the TsM cellular proteins. Their functions were mainly segregated into carbohydrate metabolism (enolase, phosphoenolpyruvate carboxykinase, phosphoglycerate kinase and glyceraldehyde 3-phosphate dehydrogenase) and cytoskeleton/cellular motility (actin, paramyosin and innexin nuc-9). Those proteins had direct (physical) and/or indirect (functional) relationships along with their biochemical properties and biological roles. Conclusion Protein repertoires strongly suggest that TsMFas and CC may symbiotically mediate protein-protein interactions during biological processes to maintain efficacious homeostatic functions and ensure the prolonged survival of TsM in the host. Electronic supplementary material The online version of this article (10.1186/s13071-017-2359-2) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Chun-Seob Ahn
- Department of Molecular Parasitology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, 16419, South Korea
| | - Jeong-Geun Kim
- Department of Molecular Parasitology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, 16419, South Korea
| | - Young-An Bae
- Department of Microbiology, Gachon University College of Medicine, Incheon, 21936, South Korea
| | - Seon-Hee Kim
- Department of Microbiology, Gachon University College of Medicine, Incheon, 21936, South Korea
| | - Joo-Ho Shin
- Division of Pharmacology, Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, 16419, South Korea
| | - Yichao Yang
- Guangxi Centers for Disease Prevention and Control, Nanning, Guangxi, 53002, China
| | - Insug Kang
- Department of Molecular Biology and Biochemistry, School of Medicine, Kyung Hee University, Seoul, 02447, South Korea
| | - Yoon Kong
- Department of Molecular Parasitology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, 16419, South Korea.
| |
Collapse
|
190
|
Jacobsen MM, Tokareva OS, Ebrahimi D, Huang W, Ling S, Dinjaski N, Li D, Simon M, Staii C, Buehler MJ, Kaplan DL, Wong JY. Effect of Terminal Modification on the Molecular Assembly and Mechanical Properties of Protein-Based Block Copolymers. Macromol Biosci 2017; 17:10.1002/mabi.201700095. [PMID: 28665510 PMCID: PMC5600892 DOI: 10.1002/mabi.201700095] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/03/2017] [Indexed: 01/13/2023]
Abstract
Accurate prediction and validation of the assembly of bioinspired peptide sequences into fibers with defined mechanical characteristics would aid significantly in designing and creating materials with desired properties. This process may also be utilized to provide insight into how the molecular architecture of many natural protein fibers is assembled. In this work, computational modeling and experimentation are used in tandem to determine how peptide terminal modification affects a fiber-forming core domain. Modeling shows that increased terminal molecular weight and hydrophilicity improve peptide chain alignment under shearing conditions and promote consolidation of semicrystalline domains. Mechanical analysis shows acute improvements to strength and elasticity, but significantly reduced extensibility and overall toughness. These results highlight an important entropic function that terminal domains of fiber-forming peptides exhibit as chain alignment promoters, which ultimately has notable consequences on the mechanical behavior of the final fiber products.
Collapse
Affiliation(s)
- Matthew M Jacobsen
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Olena S Tokareva
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Davoud Ebrahimi
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Wenwen Huang
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Shengjie Ling
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Nina Dinjaski
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - David Li
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Marc Simon
- Department of Physics and Astronomy, Center for Nanoscopic Physics, Tufts University, Medford, MA, 02155, USA
| | - Cristian Staii
- Department of Physics and Astronomy, Center for Nanoscopic Physics, Tufts University, Medford, MA, 02155, USA
| | - Markus J Buehler
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Joyce Y Wong
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
- Division of Materials Science and Engineering, Boston University, Boston, MA, 02215, USA
| |
Collapse
|
191
|
Role of G Protein-Coupled Receptors in the Regulation of Structural Plasticity and Cognitive Function. Molecules 2017; 22:molecules22071239. [PMID: 28737723 PMCID: PMC6152405 DOI: 10.3390/molecules22071239] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 07/14/2017] [Indexed: 12/26/2022] Open
Abstract
Cognition and other higher brain functions are known to be intricately associated with the capacity of neural circuits to undergo structural reorganization. Structural remodelling of neural circuits, or structural plasticity, in the hippocampus plays a major role in learning and memory. Dynamic modifications of neuronal connectivity in the form of dendritic spine morphology alteration, as well as synapse formation and elimination, often result in the strengthening or weakening of specific neural circuits that determine synaptic plasticity. Changes in dendritic complexity and synapse number are mediated by cellular processes that are regulated by extracellular signals such as neurotransmitters and neurotrophic factors. As many neurotransmitters act on G protein-coupled receptors (GPCRs), it has become increasingly apparent that GPCRs can regulate structural plasticity through a myriad of G protein-dependent pathways and non-canonical signals. A thorough understanding of how GPCRs exert their regulatory influence on dendritic spine morphogenesis may provide new insights for treating cognitive impairment and decline in various age-related diseases. In this article, we review the evidence of GPCR-mediated regulation of structural plasticity, with a special emphasis on the involvement of common as well as distinct signalling pathways that are regulated by major neurotransmitters.
Collapse
|
192
|
Sui Z, Gokhin DS, Nowak RB, Guo X, An X, Fowler VM. Stabilization of F-actin by tropomyosin isoforms regulates the morphology and mechanical behavior of red blood cells. Mol Biol Cell 2017; 28:2531-2542. [PMID: 28720661 PMCID: PMC5597325 DOI: 10.1091/mbc.e16-10-0699] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 07/14/2017] [Accepted: 07/14/2017] [Indexed: 01/17/2023] Open
Abstract
The absence of Tpm3.1 in red blood cells (RBCs) induces a compensatory increase in Tpm1.9 and abnormally stable F-actin in the membrane skeleton, with reduced association of Band 3 and glycophorin A, leading to a compensated hemolytic anemia with abnormal RBC shapes and mechanical properties. The short F-actins in the red blood cell (RBC) membrane skeleton are coated along their lengths by an equimolar combination of two tropomyosin isoforms, Tpm1.9 and Tpm3.1. We hypothesized that tropomyosin’s ability to stabilize F-actin regulates RBC morphology and mechanical properties. To test this, we examined mice with a targeted deletion in alternatively spliced exon 9d of Tpm3 (Tpm3/9d–/–), which leads to absence of Tpm3.1 in RBCs along with a compensatory increase in Tpm1.9 of sufficient magnitude to maintain normal total tropomyosin content. The isoform switch from Tpm1.9/Tpm3.1 to exclusively Tpm1.9 does not affect membrane skeleton composition but causes RBC F-actins to become hyperstable, based on decreased vulnerability to latrunculin-A–induced depolymerization. Unexpectedly, this isoform switch also leads to decreased association of Band 3 and glycophorin A with the membrane skeleton, suggesting that tropomyosin isoforms regulate the strength of F-actin-to-membrane linkages. Tpm3/9d–/– mice display a mild compensated anemia, in which RBCs have spherocytic morphology with increased osmotic fragility, reduced membrane deformability, and increased membrane stability. We conclude that RBC tropomyosin isoforms directly influence RBC physiology by regulating 1) the stability of the short F-actins in the membrane skeleton and 2) the strength of linkages between the membrane skeleton and transmembrane glycoproteins.
Collapse
Affiliation(s)
- Zhenhua Sui
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - David S Gokhin
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Roberta B Nowak
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Xinhua Guo
- Laboratory of Membrane Biology, New York Blood Center, New York, NY 10065
| | - Xiuli An
- Laboratory of Membrane Biology, New York Blood Center, New York, NY 10065.,School of Life Science, Zhengzhou University, Henan, Zhengzhou 450001, China
| | - Velia M Fowler
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
| |
Collapse
|
193
|
Sun M, Spill F, Zaman MH. A Computational Model of YAP/TAZ Mechanosensing. Biophys J 2017; 110:2540-2550. [PMID: 27276271 DOI: 10.1016/j.bpj.2016.04.040] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/24/2016] [Accepted: 04/12/2016] [Indexed: 12/15/2022] Open
Abstract
In cell proliferation, stem cell differentiation, chemoresistance, and tissue organization, the ubiquitous role of YAP/TAZ continues to impact our fundamental understanding in numerous physiological and disease systems. YAP/TAZ is an important signaling nexus integrating diverse mechanical and biochemical signals, such as ECM stiffness, adhesion ligand density, or cell-cell contacts, and thus strongly influences cell fate. Recent studies show that YAP/TAZ mechanical sensing is dependent on RhoA-regulated stress fibers. However, current understanding of YAP/TAZ remains limited due to the unknown interaction between the canonical Hippo pathway and cell tension. Furthermore, the multiscale relationship connecting adhesion signaling to YAP/TAZ activity through cytoskeleton dynamics remains poorly understood. To identify the roles of key signaling molecules in mechanical signal sensing and transduction, we present a, to our knowledge, novel computational model of the YAP/TAZ signaling pathway. This model converts extracellular-matrix mechanical properties to biochemical signals via adhesion, and integrates intracellular signaling cascades associated with cytoskeleton dynamics. We perform perturbations of molecular levels and sensitivity analyses to predict how various signaling molecules affect YAP/TAZ activity. Adhesion molecules, such as FAK, are predicted to rescue YAP/TAZ activity in soft environments via the RhoA pathway. We also found that changes of molecule concentrations result in different patterns of YAP/TAZ stiffness response. We also investigate the sensitivity of YAP/TAZ activity to ECM stiffness, and compare with that of SRF/MAL, which is another important regulator of differentiation. In addition, the model shows that the unresolved synergistic effect of YAP/TAZ activity between the mechanosensing and the Hippo pathways can be explained by the interaction of LIM-kinase and LATS. Overall, our model provides a, to our knowledge, novel platform for studying YAP/TAZ activity in the context of integrating different signaling pathways. This platform can be used to gain, to our knowledge, new fundamental insights into roles of key molecular and mechanical regulators on development, tissue engineering, or tumor progression.
Collapse
Affiliation(s)
- Meng Sun
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | - Fabian Spill
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.
| | - Muhammad H Zaman
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts; Howard Hughes Medical Institute, Boston University, Boston, Massachusetts.
| |
Collapse
|
194
|
Lei W, Myers KR, Rui Y, Hladyshau S, Tsygankov D, Zheng JQ. Phosphoinositide-dependent enrichment of actin monomers in dendritic spines regulates synapse development and plasticity. J Cell Biol 2017; 216:2551-2564. [PMID: 28659327 PMCID: PMC5551708 DOI: 10.1083/jcb.201612042] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 04/03/2017] [Accepted: 05/18/2017] [Indexed: 12/17/2022] Open
Abstract
Dendritic spines are small actin–based protrusions that serve as the postsynaptic platform for most excitatory synapses in the vertebrate brain. This study reveals a novel mechanism by which activity-dependent local enrichment of G-actin in dendritic spines regulates the remodeling of the actin cytoskeleton underlying synapse development and plasticity. Dendritic spines are small postsynaptic compartments of excitatory synapses in the vertebrate brain that are modified during learning, aging, and neurological disorders. The formation and modification of dendritic spines depend on rapid assembly and dynamic remodeling of the actin cytoskeleton in this highly compartmentalized space, but the precise mechanisms remain to be fully elucidated. In this study, we report that spatiotemporal enrichment of actin monomers (G-actin) in dendritic spines regulates spine development and plasticity. We first show that dendritic spines contain a locally enriched pool of G-actin that can be regulated by synaptic activity. We further find that this G-actin pool functions in spine development and its modification during synaptic plasticity. Mechanistically, the relatively immobile G-actin pool in spines depends on the phosphoinositide PI(3,4,5)P3 and involves the actin monomer–binding protein profilin. Together, our results have revealed a novel mechanism by which dynamic enrichment of G-actin in spines regulates the actin remodeling underlying synapse development and plasticity.
Collapse
Affiliation(s)
- Wenliang Lei
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA.,Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA
| | - Kenneth R Myers
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA.,Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA
| | - Yanfang Rui
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA.,Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA
| | - Siarhei Hladyshau
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA
| | - Denis Tsygankov
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA
| | - James Q Zheng
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA .,Department of Neurology, Emory University School of Medicine, Atlanta, GA.,Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA
| |
Collapse
|
195
|
Cheng B, Lin M, Li Y, Huang G, Yang H, Genin GM, Deshpande VS, Lu TJ, Xu F. An Integrated Stochastic Model of Matrix-Stiffness-Dependent Filopodial Dynamics. Biophys J 2017; 111:2051-2061. [PMID: 27806285 DOI: 10.1016/j.bpj.2016.09.026] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/18/2016] [Accepted: 09/19/2016] [Indexed: 11/25/2022] Open
Abstract
The ways that living cells regulate their behavior in response to their local mechanical environment underlie growth, development, and healing and are important to critical pathologies such as metastasis and fibrosis. Although extensive experimental evidence supports the hypothesis that this regulation is governed by the dependence of filopodial dynamics upon extracellular matrix stiffness, the pathways for this dependence are unclear. We therefore developed a model to relate filopodial focal adhesion dynamics to integrin-mediated Rho signaling kinetics. Results showed that focal adhesion maturation, i.e., focal adhesion links reinforcement and integrin clustering, dominates over filopodial dynamics. Downregulated focal adhesion maturation leads to the biphasic relationship between extracellular matrix stiffness and retrograde flow that has been observed in embryonic chick forebrain neurons, whereas upregulated maturation leads to the monotonically decreasing relationship that has been observed in mouse embryonic fibroblasts. When integrin-mediated Rho activation and stress-dependent focal adhesion maturation are combined, the model shows how filopodial dynamics endows cells with exquisite mechanosensing. Taken together, the results support the hypothesis that mechanical and structural factors combine with signaling kinetics to enable cells to probe their environments via filopodial dynamics.
Collapse
Affiliation(s)
- Bo Cheng
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
| | - Min Lin
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
| | - Yuhui Li
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
| | - Guoyou Huang
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
| | - Hui Yang
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China
| | - Guy M Genin
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
| | - Vikram S Deshpande
- Department of Engineering, University of Cambridge, Cambridge, United Kingdom
| | - Tian Jian Lu
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
| | - Feng Xu
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China.
| |
Collapse
|
196
|
Steric Effects Induce Geometric Remodeling of Actin Bundles in Filopodia. Biophys J 2017; 110:2066-75. [PMID: 27166814 PMCID: PMC4939473 DOI: 10.1016/j.bpj.2016.03.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 11/20/2022] Open
Abstract
Filopodia are ubiquitous fingerlike protrusions, spawned by many eukaryotic cells, to probe and interact with their environments. Polymerization dynamics of actin filaments, comprising the structural core of filopodia, largely determine their instantaneous lengths and overall lifetimes. The polymerization reactions at the filopodial tip require transport of G-actin, which enter the filopodial tube from the filopodial base and diffuse toward the filament barbed ends near the tip. Actin filaments are mechanically coupled into a tight bundle by cross-linker proteins. Interestingly, many of these proteins are relatively short, restricting the free diffusion of cytosolic G-actin throughout the bundle and, in particular, its penetration into the bundle core. To investigate the effect of steric restrictions on G-actin diffusion by the porous structure of filopodial actin filament bundle, we used a particle-based stochastic simulation approach. We discovered that excluded volume interactions result in partial and then full collapse of central filaments in the bundle, leading to a hollowed-out structure. The latter may further collapse radially due to the activity of cross-linking proteins, hence producing conical-shaped filament bundles. Interestingly, electron microscopy experiments on mature filopodia indeed frequently reveal actin bundles that are narrow at the tip and wider at the base. Overall, our work demonstrates that excluded volume effects in the context of reaction-diffusion processes in porous networks may lead to unexpected geometric growth patterns and complicated, history-dependent dynamics of intermediate metastable configurations.
Collapse
|
197
|
Mierzwa BE, Chiaruttini N, Redondo-Morata L, von Filseck JM, König J, Larios J, Poser I, Müller-Reichert T, Scheuring S, Roux A, Gerlich DW. Dynamic subunit turnover in ESCRT-III assemblies is regulated by Vps4 to mediate membrane remodelling during cytokinesis. Nat Cell Biol 2017; 19:787-798. [PMID: 28604678 PMCID: PMC5493987 DOI: 10.1038/ncb3559] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 05/19/2017] [Indexed: 02/07/2023]
Abstract
The Endosomal Sorting Complex Required for Transport (ESCRT)-III mediates membrane fission in fundamental cellular processes, including cytokinesis. ESCRT-III is thought to form persistent filaments that over time increase their curvature to constrict membranes. Unexpectedly, we found that ESCRT-III at the midbody of human cells rapidly turns over subunits with cytoplasmic pools while gradually forming larger assemblies. ESCRT-III turnover depended on the ATPase VPS4, which accumulated at the midbody simultaneously with ESCRT-III subunits, and was required for assembly of functional ESCRT-III structures. In vitro, the Vps2/Vps24 subunits of ESCRT-III formed side-by-side filaments with Snf7 and inhibited further polymerization, but the growth inhibition was alleviated by the addition of Vps4 and ATP. High-speed atomic force microscopy further revealed highly dynamic arrays of growing and shrinking ESCRT-III spirals in presence of Vps4. Continuous ESCRT-III remodeling by subunit turnover might facilitate shape adaptions to variable membrane geometries, with broad implications for diverse cellular processes.
Collapse
Affiliation(s)
- Beata E Mierzwa
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), AT-1030 Vienna, Austria
| | - Nicolas Chiaruttini
- Department of Biochemistry, University of Geneva, CH-1211 Geneva, Switzerland
| | | | | | - Julia König
- Experimental Center, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, D-01307 Dresden, Germany
| | - Jorge Larios
- Department of Biochemistry, University of Geneva, CH-1211 Geneva, Switzerland
| | - Ina Poser
- Max Planck Institute of Molecular Cell Biology and Genetics, D-01307 Dresden, Germany
| | - Thomas Müller-Reichert
- Experimental Center, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, D-01307 Dresden, Germany
| | - Simon Scheuring
- U1006 INSERM, Aix-Marseille Université, 13009 Marseille, France
| | - Aurélien Roux
- Department of Biochemistry, University of Geneva, CH-1211 Geneva, Switzerland.,Swiss National Centre for Competence in Research Programme Chemical Biology, CH-1211 Geneva, Switzerland
| | - Daniel W Gerlich
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), AT-1030 Vienna, Austria
| |
Collapse
|
198
|
Stretch-induced actomyosin contraction in epithelial tubes: Mechanotransduction pathways for tubular homeostasis. Semin Cell Dev Biol 2017; 71:146-152. [PMID: 28610943 DOI: 10.1016/j.semcdb.2017.05.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 05/24/2017] [Indexed: 02/08/2023]
Abstract
Many tissues in our body have a tubular shape and are constantly exposed to various stresses. Luminal pressure imposes tension on the epithelial and myoepithelial or smooth muscle cells surrounding the lumen of the tubes. Contractile forces generated by actomyosin assemblies within these cells oppose the luminal pressure and must be calibrated to maintain tube diameter homeostasis and tissue integrity. In this review, we discuss mechanotransduction pathways that can lead from sensation of cell stretch to activation of actomyosin contractility, providing rapid mechanochemical feedback for proper tubular tissue function.
Collapse
|
199
|
Schierbaum N, Rheinlaender J, Schäffer TE. Viscoelastic properties of normal and cancerous human breast cells are affected differently by contact to adjacent cells. Acta Biomater 2017; 55:239-248. [PMID: 28396292 DOI: 10.1016/j.actbio.2017.04.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/14/2017] [Accepted: 04/05/2017] [Indexed: 01/07/2023]
Abstract
Malignant transformation drastically alters the mechanical properties of the cell and its response to the surrounding cellular environment. We studied the influence of the physical contact between adjacent cells in an epithelial monolayer on the viscoelastic behavior of normal MCF10A, non-invasive cancerous MCF7, and invasive cancerous MDA-MB-231 human breast cells. Using an atomic force microscopy (AFM) imaging technique termed force clamp force mapping (FCFM) to record images of the viscoelastic material properties, we found that normal MCF10A cells are stiffer and have a lower fluidity at confluent than at sparse density. Contrarily, cancerous MCF7 and MDA-MB-231 cells do not stiffen and do not decrease their fluidity when progressing from sparse to confluent density. The behavior of normal MCF10A cells appears to be governed by the formation of stable cell-cell contacts, because their disruption with a calcium-chelator (EGTA) causes the stiffness and fluidity values to return to those at sparse density. In contrast, EGTA-treatment of MCF7 and MDA-MB-231 cells does not change their viscoelastic properties. Confocal fluorescence microscopy showed that the change of the viscoelastic behavior in MCF10A cells when going from sparse to confluent density is accompanied by a remodeling of the actin cytoskeleton into thick stress fiber bundles, while in MCF7 and MDA-MB-231 cells the actin cytoskeleton is only composed of thin and short fibers, regardless of cell density. While the observed behavior of normal MCF10A cells might be crucial for providing mechanical stability and thus in turn integrity of the epithelial monolayer, the dysregulation of this behavior in cancerous MCF7 and MDA-MB-231 cells is possibly a central aspect of cancer progression in the epithelium. STATEMENT OF SIGNIFICANCE We measured the viscoelastic properties of normal and cancerous human breast epithelial cells in different states of confluency using atomic force microscopy. We found that confluent normal cells are stiffer and have lower fluidity than sparse normal cells, which appears to be governed by the formation of cell-cell contacts. Contrarily, confluent cancer cells do not stiffen and not have a decreased fluidity compared to sparse cancer cells and their viscoelastic properties are independent of cell-cell contact formation. While the observed behavior of normal cells appears to be crucial for providing the mechanical stability and therefore the integrity of the epithelial monolayer, the dysregulation of this behavior in cancer cells might be a central aspect of early stage cancer progression and metastasis in the epithelium.
Collapse
Affiliation(s)
- Nicolas Schierbaum
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Johannes Rheinlaender
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Tilman E Schäffer
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| |
Collapse
|
200
|
Pathogenic Variant in ACTB, p.Arg183Trp, Causes Juvenile-Onset Dystonia, Hearing Loss, and Developmental Delay without Midline Malformation. Case Rep Genet 2017; 2017:9184265. [PMID: 28487785 PMCID: PMC5405358 DOI: 10.1155/2017/9184265] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 03/25/2017] [Accepted: 03/30/2017] [Indexed: 11/17/2022] Open
Abstract
ACTB encodes the β-actin, and pathogenic variations in this gene have typically been associated with Baraitser-Winter cerebrofrontofacial syndrome, a congenital malformation syndrome characterized by short stature, craniofacial anomalies, and cerebral anomalies. Here, we describe the third case with the p.Arg183Trp variant in ACTB causing juvenile-onset dystonia. Our patient has severe, intractable dystonia, developmental delay, and sensorineural hearing loss, besides hyperintensities in the caudate nuclei and putamen on the brain MRI, which is a distinct but overlapping phenotype with the previously reported case of identical twins with the same alteration in ACTB.
Collapse
|