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Lindamood HL, Liu TM, Read TA, Vitriol EA. Using ALS to understand profilin 1's diverse roles in cellular physiology. Cytoskeleton (Hoboken) 2024. [PMID: 39056295 DOI: 10.1002/cm.21896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 07/03/2024] [Accepted: 07/10/2024] [Indexed: 07/28/2024]
Abstract
Profilin is an actin monomer-binding protein whose role in actin polymerization has been studied for nearly 50 years. While its principal biochemical features are now well understood, many questions remain about how profilin controls diverse processes within the cell. Dysregulation of profilin has been implicated in a broad range of human diseases, including neurodegeneration, inflammatory disorders, cardiac disease, and cancer. For example, mutations in the profilin 1 gene (PFN1) can cause amyotrophic lateral sclerosis (ALS), although the precise mechanisms that drive neurodegeneration remain unclear. While initial work suggested proteostasis and actin cytoskeleton defects as the main pathological pathways, multiple novel functions for PFN1 have since been discovered that may also contribute to ALS, including the regulation of nucleocytoplasmic transport, stress granules, mitochondria, and microtubules. Here, we will review these newly discovered roles for PFN1, speculate on their contribution to ALS, and discuss how defects in actin can contribute to these processes. By understanding profilin 1's involvement in ALS pathogenesis, we hope to gain insight into this functionally complex protein with significant influence over cellular physiology.
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Affiliation(s)
- Halli L Lindamood
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia, USA
| | - Tatiana M Liu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia, USA
| | - Tracy-Ann Read
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia, USA
| | - Eric A Vitriol
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia, USA
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2
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Chua XL, Tong CS, Su M, Xǔ XJ, Xiao S, Wu X, Wu M. Competition and synergy of Arp2/3 and formins in nucleating actin waves. Cell Rep 2024; 43:114423. [PMID: 38968072 PMCID: PMC11378572 DOI: 10.1016/j.celrep.2024.114423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 04/23/2024] [Accepted: 06/14/2024] [Indexed: 07/07/2024] Open
Abstract
Actin assembly and dynamics are crucial for maintaining cell structure and changing physiological states. The broad impact of actin on various cellular processes makes it challenging to dissect the specific role of actin regulatory proteins. Using actin waves that propagate on the cortex of mast cells as a model, we discovered that formins (FMNL1 and mDia3) are recruited before the Arp2/3 complex in actin waves. GTPase Cdc42 interactions drive FMNL1 oscillations, with active Cdc42 and the constitutively active mutant of FMNL1 capable of forming waves on the plasma membrane independently of actin waves. Additionally, the delayed recruitment of Arp2/3 antagonizes FMNL1 and active Cdc42. This antagonism is not due to competition for monomeric actin but rather for their common upstream regulator, active Cdc42, whose levels are negatively regulated by Arp2/3 via SHIP1 recruitment. Collectively, our study highlights the complex feedback loops in the dynamic control of the actin cytoskeletal network.
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Affiliation(s)
- Xiang Le Chua
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA; Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557, Singapore
| | - Chee San Tong
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA; Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557, Singapore
| | - Maohan Su
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA; Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557, Singapore; Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - X J Xǔ
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA; Department of Physics, Yale University, New Haven, CT 06511, USA
| | - Shengping Xiao
- Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557, Singapore
| | - Xudong Wu
- School of Life Sciences, Westlake University, Hangzhou 310024, China
| | - Min Wu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA; Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557, Singapore; Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.
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3
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Yang J, Zhou S, Yang Z, Shi X, Liu H, Yang Z, Peng D, Ding Z, Ye S. Silencing of the T-type voltage-gated calcium channel α 1 subunit by fungus-mediated RNAi altered the structure of F-actin and caused defective behaviors in Ditylenchus destructor. Mol Biol Rep 2024; 51:673. [PMID: 38787479 DOI: 10.1007/s11033-024-09626-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024]
Abstract
BACKGROUND T-type calcium channels, characterized as low-voltage activated (LVA) calcium channels, play crucial physiological roles across a wide range of tissues, including both the neuronal and nonneuronal systems. Using in situ hybridization and RNA interference (RNAi) techniques in vitro, we previously identified the tissue distribution and physiological function of the T-type calcium channel α1 subunit (DdCα1G) in the plant-parasitic nematode Ditylenchus destructor. METHODS AND RESULTS To further characterize the functional role of DdCα1G, we employed a combination of immunohistochemistry and fungus-mediated RNAi and found that DdCα1G was clearly distributed in stylet-related tissue, oesophageal gland-related tissue, secretory-excretory duct-related tissue and male spicule-related tissue. Silencing DdCα1G led to impairments in the locomotion, feeding, reproductive ability and protein secretion of nematodes. To confirm the defects in behavior, we used phalloidin staining to examine muscle changes in DdCα1G-RNAi nematodes. Our observations demonstrated that defective behaviors are associated with related muscular atrophy. CONCLUSION Our findings provide a deeper understanding of the physiological functions of T-type calcium channels in plant-parasitic nematodes. The T-type calcium channel can be considered a promising target for sustainable nematode management practices.
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Affiliation(s)
- Jiahao Yang
- College of Plant Protection, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Siyu Zhou
- College of Plant Protection, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Ziqi Yang
- College of Plant Protection, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Xuqi Shi
- College of Plant Protection, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Haoran Liu
- College of Plant Protection, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Zhuhong Yang
- College of Plant Protection, Hunan Agricultural University, Changsha, Hunan, 410128, China
- Hunan Provincial Engineering & Technology Research Center for Biopesticide and Formulation Processing, Changsha, Hunan, 410128, China
| | - Deliang Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Zhong Ding
- College of Plant Protection, Hunan Agricultural University, Changsha, Hunan, 410128, China.
- Hunan Provincial Engineering & Technology Research Center for Biopesticide and Formulation Processing, Changsha, Hunan, 410128, China.
| | - Shan Ye
- College of Plant Protection, Hunan Agricultural University, Changsha, Hunan, 410128, China.
- Hunan Provincial Engineering & Technology Research Center for Biopesticide and Formulation Processing, Changsha, Hunan, 410128, China.
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4
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Olejárová S, Horváth D, Huntošová V. The Remodulation of Actin Bundles during the Stimulation of Mitochondria in Adult Human Fibroblasts in Response to Light. Pharmaceutics 2023; 16:20. [PMID: 38258031 PMCID: PMC10818370 DOI: 10.3390/pharmaceutics16010020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/12/2023] [Accepted: 12/15/2023] [Indexed: 01/24/2024] Open
Abstract
β-actin belongs to cytoskeletal structures that change dynamically in cells according to various stimuli. Human skin can be considered as an organ that is very frequently exposed to various stress factors, of which light plays an important role. The present study focuses on adult human fibroblasts exposed to two types of light stress. Orange light with a wavelength of 590 nm was used here to stimulate the photosensitizer localized in the cells as a residual dose of photodynamic therapy (PDT). On the other hand, near-infrared light with a wavelength of 808 nm was considered for photobiomodulation (PBM), which is often used in healing processes. Confocal fluorescence microscopy was used to observe changes in intercellular communication, mitochondrial structures, and cytoskeletal dynamics defined by the remodulation of β-actin of fibroblasts. The number of β-actin bundles forming spherical structures was detected after light exposure. These structures as β-actin oligomers were confirmed with super-resolution microscopy. While PDT led to the disintegration of actin oligomers, PBM increased their number. The interaction of β-actin with mitochondria was observed. The combination of PDT and PBM treatments is important to minimize the side effects of cancer treatment with PDT on healthy cells, as shown by the cell metabolism assay in this work. In this work, β-actin is presented as an important parameter that changes and is involved in the response of cells to PDT and PBM.
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Affiliation(s)
- Soňa Olejárová
- Department of Biophysics, Institute of Physics, Faculty of Science, P.J. Šafárik University in Košice, Jesenná 5, 041 54 Kosice, Slovakia;
| | - Denis Horváth
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, P.J. Šafárik University in Košice, Jesenná 5, 041 54 Košice, Slovakia;
| | - Veronika Huntošová
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, P.J. Šafárik University in Košice, Jesenná 5, 041 54 Košice, Slovakia;
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5
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Le Chua X, Tong CS, Xǔ XJ, Su M, Xiao S, Wu X, Wu M. Competition and Synergy of Arp2/3 and Formins in Nucleating Actin Waves. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.13.557508. [PMID: 37745345 PMCID: PMC10515902 DOI: 10.1101/2023.09.13.557508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The assembly and disassembly of actin filaments and their regulatory proteins are crucial for maintaining cell structure or changing physiological state. However, because of the tremendous global impact of actin on diverse cellular processes, dissecting the specific role of actin regulatory proteins remains challenging. In this study, we employ actin waves that propagate on the cortex of mast cell to investigate the interplay between formins and the Arp2/3 complex in the nucleating and turnover of cortical actin. Our findings reveal that the recruitment of FMNL1 and mDia3 precedes the Arp2/3 complex in cortical actin waves. Membrane and GTPase-interaction can drive oscillations of FMNL1 in an actin-dependent manner, but active Cdc42 waves or constitutively-active FMNL1 mutant can form without actin waves. In addition to the apparent coordinated assembly of formins and Arp2/3, we further reveal their antagonism, where inhibition of Arp2/3 complex by CK-666 led to a transient increase in the recruitment of formins and actin polymerization. Our analysis suggest that the antagonism could not be explained for the competition between FMNL1 and Arp2/3 for monomeric actin. Rather, it is regulated by a limited pool of their common upstream regulator, Cdc42, whose level is negatively regulated by Arp2/3. Collectively, our study highlights the multifaceted interactions, cooperative or competitive, between formins and Arp2/3 complex, in the intricate and dynamic control of actin cytoskeletal network.
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Affiliation(s)
- Xiang Le Chua
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557
| | - Chee San Tong
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557
| | - X J Xǔ
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Physics, Yale University, New Haven, CT 06511, USA
| | - Maohan Su
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557
- Mechanobiology Institute, National University of Singapore, Singapore 117411
| | - Shengping Xiao
- Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557
| | - Xudong Wu
- School of Life Sciences, Westlake University, Hangzhou, China 310024
| | - Min Wu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Biological Sciences, Centre for Bioimaging Sciences, Singapore 117557
- Department of Physics, Yale University, New Haven, CT 06511, USA
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6
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Romero MD, Carabeo RA. Distinct roles of the Chlamydia trachomatis effectors TarP and TmeA in the regulation of formin and Arp2/3 during entry. J Cell Sci 2022; 135:jcs260185. [PMID: 36093837 PMCID: PMC9659389 DOI: 10.1242/jcs.260185] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 09/05/2022] [Indexed: 12/13/2022] Open
Abstract
The obligate intracellular pathogen Chlamydia trachomatis manipulates the host actin cytoskeleton to assemble actin-rich structures that drive pathogen entry. The recent discovery of TmeA, which, like TarP, is an invasion-associated type III effector implicated in actin remodeling, raised questions regarding the nature of their functional interaction. Quantitative live-cell imaging of actin remodeling at invasion sites revealed differences in recruitment and turnover kinetics associated with the TarP and TmeA pathways, with the former accounting for most of the robust actin dynamics at invasion sites. TarP-mediated recruitment of actin nucleators, i.e. formins and the Arp2/3 complex, was crucial for rapid actin kinetics, generating a collaborative positive feedback loop that enhanced their respective actin-nucleating activities within invasion sites. In contrast, the formin Fmn1 was not recruited to invasion sites and did not collaborate with Arp2/3 within the context of TmeA-associated actin recruitment. Although the TarP-Fmn1-Arp2/3 signaling axis is responsible for the majority of actin dynamics, its inhibition had similar effects as the deletion of TmeA on invasion efficiency, consistent with the proposed model that TarP and TmeA act on different stages of the same invasion pathway.
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Affiliation(s)
- Matthew D. Romero
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, NE 68198-5900, USA
| | - Rey A. Carabeo
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, NE 68198-5900, USA
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7
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Huang Y, Winklbauer R. Cell cortex regulation by the planar cell polarity protein Prickle1. J Cell Biol 2022; 221:e202008116. [PMID: 35512799 PMCID: PMC9082893 DOI: 10.1083/jcb.202008116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 01/18/2022] [Accepted: 04/09/2022] [Indexed: 01/07/2023] Open
Abstract
The planar cell polarity pathway regulates cell polarity, adhesion, and rearrangement. Its cytoplasmic core components Prickle (Pk) and Dishevelled (Dvl) often localize as dense puncta at cell membranes to form antagonizing complexes and establish cell asymmetry. In vertebrates, Pk and Dvl have been implicated in actomyosin cortex regulation, but the mechanism of how these proteins control cell mechanics is unclear. Here we demonstrate that in Xenopus prechordal mesoderm cells, diffusely distributed, cytoplasmic Pk1 up-regulates the F-actin content of the cortex. This counteracts cortex down-regulation by Dvl2. Both factors act upstream of casein kinase II to increase or decrease cortical tension. Thus, cortex modulation by Pk1 and Dvl2 is translated into mechanical force and affects cell migration and rearrangement during radial intercalation in the prechordal mesoderm. Pk1 also forms puncta and plaques, which are associated with localized depletion of cortical F-actin, suggesting opposite roles for diffuse and punctate Pk1.
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Affiliation(s)
- Yunyun Huang
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Rudolf Winklbauer
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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8
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García-Padilla C, Muñoz-Gallardo MDM, Lozano-Velasco E, Castillo-Casas JM, Caño-Carrillo S, García-López V, Aránega A, Franco D, García-Martínez V, López-Sánchez C. New Insights into the Roles of lncRNAs as Modulators of Cytoskeleton Architecture and Their Implications in Cellular Homeostasis and in Tumorigenesis. Noncoding RNA 2022; 8:ncrna8020028. [PMID: 35447891 PMCID: PMC9033079 DOI: 10.3390/ncrna8020028] [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] [Received: 02/16/2022] [Revised: 03/31/2022] [Accepted: 04/09/2022] [Indexed: 11/20/2022] Open
Abstract
The importance of the cytoskeleton not only in cell architecture but also as a pivotal element in the transduction of signals that mediate multiple biological processes has recently been highlighted. Broadly, the cytoskeleton consists of three types of structural proteins: (1) actin filaments, involved in establishing and maintaining cell shape and movement; (2) microtubules, necessary to support the different organelles and distribution of chromosomes during cell cycle; and (3) intermediate filaments, which have a mainly structural function showing specificity for the cell type where they are expressed. Interaction between these protein structures is essential for the cytoskeletal mesh to be functional. Furthermore, the cytoskeleton is subject to intense spatio-temporal regulation mediated by the assembly and disassembly of its components. Loss of cytoskeleton homeostasis and integrity of cell focal adhesion are hallmarks of several cancer types. Recently, many reports have pointed out that lncRNAs could be critical mediators in cellular homeostasis controlling dynamic structure and stability of the network formed by cytoskeletal structures, specifically in different types of carcinomas. In this review, we summarize current information available about the roles of lncRNAs as modulators of actin dependent cytoskeleton and their impact on cancer pathogenesis. Finally, we explore other examples of cytoskeletal lncRNAs currently unrelated to tumorigenesis, to illustrate knowledge about them.
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Affiliation(s)
- Carlos García-Padilla
- Department of Human Anatomy and Embryology, Faculty of Medicine, Institute of Molecular Pathology Biomarkers, University of Extremadura, 06006 Badajoz, Spain; (E.L.-V.); (V.G.-L.); (V.G.-M.)
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (M.d.M.M.-G.); (J.M.C.-C.); (S.C.-C.); (A.A.); (D.F.)
- Correspondence: (C.G.-P.); (C.L.-S.)
| | - María del Mar Muñoz-Gallardo
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (M.d.M.M.-G.); (J.M.C.-C.); (S.C.-C.); (A.A.); (D.F.)
| | - Estefanía Lozano-Velasco
- Department of Human Anatomy and Embryology, Faculty of Medicine, Institute of Molecular Pathology Biomarkers, University of Extremadura, 06006 Badajoz, Spain; (E.L.-V.); (V.G.-L.); (V.G.-M.)
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (M.d.M.M.-G.); (J.M.C.-C.); (S.C.-C.); (A.A.); (D.F.)
- Fundación Medina, 18016 Granada, Spain
| | - Juan Manuel Castillo-Casas
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (M.d.M.M.-G.); (J.M.C.-C.); (S.C.-C.); (A.A.); (D.F.)
| | - Sheila Caño-Carrillo
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (M.d.M.M.-G.); (J.M.C.-C.); (S.C.-C.); (A.A.); (D.F.)
| | - Virginio García-López
- Department of Human Anatomy and Embryology, Faculty of Medicine, Institute of Molecular Pathology Biomarkers, University of Extremadura, 06006 Badajoz, Spain; (E.L.-V.); (V.G.-L.); (V.G.-M.)
| | - Amelia Aránega
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (M.d.M.M.-G.); (J.M.C.-C.); (S.C.-C.); (A.A.); (D.F.)
- Fundación Medina, 18016 Granada, Spain
| | - Diego Franco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (M.d.M.M.-G.); (J.M.C.-C.); (S.C.-C.); (A.A.); (D.F.)
- Fundación Medina, 18016 Granada, Spain
| | - Virginio García-Martínez
- Department of Human Anatomy and Embryology, Faculty of Medicine, Institute of Molecular Pathology Biomarkers, University of Extremadura, 06006 Badajoz, Spain; (E.L.-V.); (V.G.-L.); (V.G.-M.)
| | - Carmen López-Sánchez
- Department of Human Anatomy and Embryology, Faculty of Medicine, Institute of Molecular Pathology Biomarkers, University of Extremadura, 06006 Badajoz, Spain; (E.L.-V.); (V.G.-L.); (V.G.-M.)
- Correspondence: (C.G.-P.); (C.L.-S.)
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9
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Das S, Zhang Z, Kalvakota S, Soto R, Phillips ML, Terman JR, Reisler E. Parallel actin monomers in the 8S complex of actin-INF2. J Biomol Struct Dyn 2022; 41:3295-3304. [PMID: 35343388 PMCID: PMC10368088 DOI: 10.1080/07391102.2022.2050947] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Polymerization and depolymerization of actin play an essential role in eukaryotic cells. Actin exists in cells in both monomeric (G-actin) and filamentous (polymer, F-actin) forms. Actin binding proteins (ABPs) facilitate the transition between these two states, and their interactions with these two states of actin are critical for actin-based cellular processes. Rapid depolymerization of actin is assisted in the brain and/or other cells by its oxidation by the enzyme Mical (yielding Mox-actin), and/or by the binding of Inverted Formin 2 (INF2) - which can also accelerate filaments formation. At their stoichiometric molar ratio INF2 and actin yield the 8S complex (consisting of 4 actin monomers: 2 INF2 dimer molecules). Using biochemical and biophysical methods, we investigate the structural arrangement of actin in the 8S particles and the interaction of INF2 with actin and Mox-actin. To that end, we show 2 D class averages of 8S particles obtained by negative staining electron microscopy. We also show that: (i) 8S particles can seed rapid actin assembly; (ii) Mox-actin and INF2 form 8S particles at proteins ratios similar to those of unoxidized actin; (iii) chemical crosslinkings suggest that actin monomers are in a parallel orientation in the 8S particles of both actin and Mox-actin; and (iv) INF2 accelerates the disassembly of Mox-F-actin. Our results provide better understanding of actin's arrangement in the 8S particles formed during actin depolymerization and in the early polymerization stages of both actin and Mox-actin.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Sanchaita Das
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Zixin Zhang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Saichandra Kalvakota
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Raul Soto
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Martin L Phillips
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Jonathan R Terman
- Departments of Neuroscience and Pharmacology, The University of Texas of Southwestern Medical Center, Dallas, TX, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA.,Molecular Biology Institute, University of California, Los Angeles, CA, USA
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Gibieža P, Petrikaitė V. The regulation of actin dynamics during cell division and malignancy. Am J Cancer Res 2021; 11:4050-4069. [PMID: 34659876 PMCID: PMC8493394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/29/2021] [Indexed: 06/13/2023] Open
Abstract
Actin is the most abundant protein in almost all the eukaryotic cells. Actin amino acid sequences are highly conserved and have not changed a lot during the progress of evolution, varying by no more than 20% in the completely different species, such as humans and algae. The network of actin filaments plays a crucial role in regulating cells' cytoskeleton that needs to undergo dynamic tuning and structural changes in order for various functional processes, such as cell motility, migration, adhesion, polarity establishment, cell growth and cell division, to take place in live cells. Owing to its fundamental role in the cell, actin is a prominent regulator of cell division, a process, whose success directly depends on morphological changes of actin cytoskeleton and correct segregation of duplicated chromosomes. Disorganization of actin framework during the last stage of cell division, known as cytokinesis, can lead to multinucleation and formation of polyploidy in post-mitotic cells, eventually developing into cancer. In this review, we will cover the principles of actin regulation during cell division and discuss how the control of actin dynamics is altered during the state of malignancy.
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Affiliation(s)
- Paulius Gibieža
- Laboratory of Drug Targets Histopathology, Institute of Cardiology, Lithuanian University of Health Sciences Kaunas, LT-50162, Lithuania
| | - Vilma Petrikaitė
- Laboratory of Drug Targets Histopathology, Institute of Cardiology, Lithuanian University of Health Sciences Kaunas, LT-50162, Lithuania
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11
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Zaatri A, Perry JA, Maddox AS. Septins and a formin have distinct functions in anaphase chiral cortical rotation in the Caenorhabditis elegans zygote. Mol Biol Cell 2021; 32:1283-1292. [PMID: 34010018 PMCID: PMC8351551 DOI: 10.1091/mbc.e20-09-0576] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Many cells and tissues exhibit chirality that stems from the chirality of proteins and polymers. In the Caenorhabditis elegans zygote, actomyosin contractility drives chiral rotation of the entire cortex circumferentially around the division plane during anaphase. How contractility is translated to cell-scale chirality, and what dictates handedness, are unknown. Septins are candidate contributors to cell-scale chirality because they anchor and cross-link the actomyosin cytoskeleton. We report that septins are required for anaphase cortical rotation. In contrast, the formin CYK-1, which we found to be enriched in the posterior in early anaphase, is not required for cortical rotation but contributes to its chirality. Simultaneous loss of septin and CYK-1 function led to abnormal and often reversed cortical rotation. Our results suggest that anaphase contractility leads to chiral rotation by releasing torsional stress generated during formin-based polymerization, which is polarized along the cell anterior–posterior axis and which accumulates due to actomyosin network connectivity. Our findings shed light on the molecular and physical bases for cellular chirality in the C. elegans zygote. We also identify conditions in which chiral rotation fails but animals are developmentally viable, opening avenues for future work on the relationship between early embryonic cellular chirality and animal body plan.
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Affiliation(s)
- Adhham Zaatri
- Department of Biology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599
| | - Jenna A Perry
- Department of Biology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599
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12
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Rey-Suarez I, Rogers N, Kerr S, Shroff H, Upadhyaya A. Actomyosin dynamics modulate microtubule deformation and growth during T-cell activation. Mol Biol Cell 2021; 32:1641-1653. [PMID: 33826369 PMCID: PMC8684730 DOI: 10.1091/mbc.e20-10-0685] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Activation of T-cells leads to the formation of immune synapses (ISs) with antigen-presenting cells. This requires T-cell polarization and coordination between the actomyosin and microtubule cytoskeletons. The interactions between these two cytoskeletal components during T-cell activation are not well understood. Here, we elucidate the interactions between microtubules and actin at the IS with high-resolution fluorescence microscopy. We show that microtubule growth dynamics in the peripheral actin-rich region is distinct from that in the central actin-free region. We further demonstrate that these differences arise from differential involvement of Arp2/3- and formin-nucleated actin structures. Formin inhibition results in a moderate decrease in microtubule growth rates, which is amplified in the presence of integrin engagement. In contrast, Arp2/3 inhibition leads to an increase in microtubule growth rates. We find that microtubule filaments are more deformed and exhibit greater shape fluctuations in the periphery of the IS than at the center. Using small molecule inhibitors, we show that actin dynamics and actomyosin contractility play key roles in defining microtubule deformations and shape fluctuations. Our results indicate a mechanical coupling between the actomyosin and microtubule systems during T-cell activation, whereby different actin structures influence microtubule dynamics in distinct ways.
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Affiliation(s)
- Ivan Rey-Suarez
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742
| | - Nate Rogers
- Department of Physics, University of Maryland, College Park, MD 20742
| | - Sarah Kerr
- Department of Physics, University of Colorado, Boulder, CO 80302
| | - Hari Shroff
- National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
| | - Arpita Upadhyaya
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742.,Department of Physics, University of Maryland, College Park, MD 20742
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13
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Xu K, Zhang Z, Chen M, Moqbel SAA, He Y, Ma C, Jiang L, Xiong Y, Wu L. Nesfatin-1 Promotes the Osteogenic Differentiation of Tendon-Derived Stem Cells and the Pathogenesis of Heterotopic Ossification in Rat Tendons via the mTOR Pathway. Front Cell Dev Biol 2020; 8:547342. [PMID: 33344440 PMCID: PMC7744791 DOI: 10.3389/fcell.2020.547342] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 11/13/2020] [Indexed: 12/11/2022] Open
Abstract
Heterotopic ossification (HO) is a pathological condition involved in tendinopathy. Adipokines are known to play a key role in HO of tendinopathy. Nesfatin-1, an 82-amino acid adipokine is closely reportedly associated with diabetes mellitus (DM), which, in turn, is closely related to tendinopathy. In the present study, we aimed to investigate the effects of nesfatin-1 on the osteogenic differentiation of tendon-derived stem cells (TDSCs) and the pathogenesis of tendinopathy in rats. In vitro, TDSCs were incubated in osteogenic induction medium for 14 days with different nesfatin-1 concentration. In vivo, Sprague Dawley rats underwent Achilles tenotomy to evaluate the effect of nesfatin-1 on tendinopathy. Our results showed that the expression of nesfatin-1 expression in tendinopathy patients was significantly higher than that in healthy subjects. Nesfatin-1 affected the cytoskeleton and reduced the migration ability of TDSCs in vitro. Furthermore, nesfatin-1 inhibited the expression of Scx, Mkx, and Tnmd and promoted the expression of osteogenic genes, such as COL1a1, ALP, and RUNX2; these results suggested that nesfatin-1 inhibits cell migration, adversely impacts tendon phenotype, promotes osteogenic differentiation of TDSCs and the pathogenesis of HO in rat tendons. Moreover, we observed that nesfatin-1 suppressed autophagy and activated the mammalian target of rapamycin (mTOR) pathway both in vitro and in vivo. The suppression of the mTOR pathway alleviated nesfatin-1-induced HO development in rat tendons. Thus, nesfatin-1 promotes the osteogenic differentiation of TDSC and the pathogenesis of HO in rat tendons via the mTOR pathway; these findings highlight a new potential therapeutic target for tendinopathy.
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Affiliation(s)
- Kai Xu
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Zhanfeng Zhang
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Department of Orthopedic Surgery, The First People's Hospital of Huzhou, Huzhou, China
| | - Mengyao Chen
- Department of Medical Oncology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Safwat Adel Abdo Moqbel
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yuzhe He
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Chiyuan Ma
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lifeng Jiang
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yan Xiong
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lidong Wu
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
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14
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van Loon AP, Erofeev IS, Maryshev IV, Goryachev AB, Sagasti A. Cortical contraction drives the 3D patterning of epithelial cell surfaces. J Cell Biol 2020; 219:133677. [PMID: 32003768 PMCID: PMC7054995 DOI: 10.1083/jcb.201904144] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 09/16/2019] [Accepted: 12/17/2019] [Indexed: 12/20/2022] Open
Abstract
Cellular protrusions create complex cell surface topographies, but biomechanical mechanisms regulating their formation and arrangement are largely unknown. To study how protrusions form, we focused on the morphogenesis of microridges, elongated actin-based structures that are arranged in maze-like patterns on the apical surfaces of zebrafish skin cells. Microridges form by accreting simple finger-like precursors. Live imaging demonstrated that microridge morphogenesis is linked to apical constriction. A nonmuscle myosin II (NMII) reporter revealed pulsatile contractions of the actomyosin cortex, and inhibiting NMII blocked apical constriction and microridge formation. A biomechanical model suggested that contraction reduces surface tension to permit the fusion of precursors into microridges. Indeed, reducing surface tension with hyperosmolar media promoted microridge formation. In anisotropically stretched cells, microridges formed by precursor fusion along the stretch axis, which computational modeling explained as a consequence of stretch-induced cortical flow. Collectively, our results demonstrate how contraction within the 2D plane of the cortex can pattern 3D cell surfaces.
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Affiliation(s)
- Aaron P van Loon
- Department of Molecular, Cell and Developmental Biology and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA
| | - Ivan S Erofeev
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Ivan V Maryshev
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Andrew B Goryachev
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Alvaro Sagasti
- Department of Molecular, Cell and Developmental Biology and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA
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15
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Copos C, Mogilner A. A hybrid stochastic-deterministic mechanochemical model of cell polarization. Mol Biol Cell 2020; 31:1637-1649. [PMID: 32459563 PMCID: PMC7521800 DOI: 10.1091/mbc.e19-09-0549] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 05/11/2020] [Accepted: 05/20/2020] [Indexed: 12/15/2022] Open
Abstract
Polarization is a crucial component in cell differentiation, development, and motility, but its details are not yet well understood. At the onset of cell locomotion, cells break symmetry to form well-defined cell fronts and rears. This polarity establishment varies across cell types: in Dictyostelium discoideum cells, it is mediated by biochemical signaling pathways and can function in the absence of a cytoskeleton, while in keratocytes, it is tightly connected to cytoskeletal dynamics and mechanics. Theoretical models that have been developed to understand the onset of polarization have explored either signaling or mechanical pathways, yet few have explored mechanochemical mechanisms. However, many motile cells rely on both signaling modules and actin cytoskeleton to break symmetry and achieve a stable polarized state. We propose a general mechanochemical polarization model based on coupling between a stochastic model for the segregation of signaling molecules and a simplified mechanical model for actin cytoskeleton network competition. We find that local linear coupling between minimally nonlinear signaling and cytoskeletal systems, separately not supporting stable polarization, yields a robustly polarized cell state. The model captures the essence of spontaneous polarization of neutrophils, which has been proposed to emerge due to the competition between frontness and backness pathways.
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Affiliation(s)
- Calina Copos
- Courant Institute, New York University, New York, NY 10012
| | - Alex Mogilner
- Courant Institute, New York University, New York, NY 10012
- Department of Biology, New York University, New York, NY 10012
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16
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Cao L, Yonis A, Vaghela M, Barriga EH, Chugh P, Smith MB, Maufront J, Lavoie G, Méant A, Ferber E, Bovellan M, Alberts A, Bertin A, Mayor R, Paluch EK, Roux PP, Jégou A, Romet-Lemonne G, Charras G. SPIN90 associates with mDia1 and the Arp2/3 complex to regulate cortical actin organization. Nat Cell Biol 2020; 22:803-814. [PMID: 32572169 DOI: 10.1038/s41556-020-0531-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 05/04/2020] [Indexed: 01/02/2023]
Abstract
Cell shape is controlled by the submembranous cortex, an actomyosin network mainly generated by two actin nucleators: the Arp2/3 complex and the formin mDia1. Changes in relative nucleator activity may alter cortical organization, mechanics and cell shape. Here we investigate how nucleation-promoting factors mediate interactions between nucleators. In vitro, the nucleation-promoting factor SPIN90 promotes formation of unbranched filaments by Arp2/3, a process thought to provide the initial filament for generation of dendritic networks. Paradoxically, in cells, SPIN90 appears to favour a formin-dominated cortex. Our in vitro experiments reveal that this feature stems mainly from two mechanisms: efficient recruitment of mDia1 to SPIN90-Arp2/3 nucleated filaments and formation of a ternary SPIN90-Arp2/3-mDia1 complex that greatly enhances filament nucleation. Both mechanisms yield rapidly elongating filaments with mDia1 at their barbed ends and SPIN90-Arp2/3 at their pointed ends. Thus, in networks, SPIN90 lowers branching densities and increases the proportion of long filaments elongated by mDia1.
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Affiliation(s)
- Luyan Cao
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Amina Yonis
- London Centre for Nanotechnology, University College London, London, UK.,Department of Cell and Developmental Biology, University College London, London, UK
| | - Malti Vaghela
- London Centre for Nanotechnology, University College London, London, UK.,Department of Physics and Astronomy, University College London, London, UK
| | - Elias H Barriga
- Department of Cell and Developmental Biology, University College London, London, UK.,Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Priyamvada Chugh
- MRC-Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Matthew B Smith
- MRC-Laboratory for Molecular Cell Biology, University College London, London, UK.,The Francis Crick institute, London, UK
| | - Julien Maufront
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Universités, Paris, France
| | - Geneviève Lavoie
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada
| | - Antoine Méant
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada
| | - Emma Ferber
- London Centre for Nanotechnology, University College London, London, UK
| | - Miia Bovellan
- London Centre for Nanotechnology, University College London, London, UK.,Department of Cell and Developmental Biology, University College London, London, UK
| | - Art Alberts
- Van Andel research institute, Grand Rapids, MI, USA
| | - Aurélie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Universités, Paris, France
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Ewa K Paluch
- MRC-Laboratory for Molecular Cell Biology, University College London, London, UK.,Institute for the Physics of Living Systems, University College London, London, UK.,Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Philippe P Roux
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada.,Department of Pathology and Cell Biology, Université de Montréal, Montréal, Canada
| | - Antoine Jégou
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France.
| | | | - Guillaume Charras
- London Centre for Nanotechnology, University College London, London, UK. .,Department of Cell and Developmental Biology, University College London, London, UK. .,Institute for the Physics of Living Systems, University College London, London, UK.
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17
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Skruber K, Warp PV, Shklyarov R, Thomas JD, Swanson MS, Henty-Ridilla JL, Read TA, Vitriol EA. Arp2/3 and Mena/VASP Require Profilin 1 for Actin Network Assembly at the Leading Edge. Curr Biol 2020; 30:2651-2664.e5. [PMID: 32470361 DOI: 10.1016/j.cub.2020.04.085] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/09/2020] [Accepted: 04/29/2020] [Indexed: 12/27/2022]
Abstract
Cells have many types of actin structures, which must assemble from a common monomer pool. Yet, it remains poorly understood how monomers are distributed to and shared between different filament networks. Simplified model systems suggest that monomers are limited and heterogeneous, which alters actin network assembly through biased polymerization and internetwork competition. However, less is known about how monomers influence complex actin structures, where different networks competing for monomers overlap and are functionally interdependent. One example is the leading edge of migrating cells, which contains filament networks generated by multiple assembly factors. The leading edge dynamically switches between the formation of different actin structures, such as lamellipodia or filopodia, by altering the balance of these assembly factors' activities. Here, we sought to determine how the monomer-binding protein profilin 1 (PFN1) controls the assembly and organization of actin in mammalian cells. Actin polymerization in PFN1 knockout cells was severely disrupted, particularly at the leading edge, where both Arp2/3 and Mena/VASP-based filament assembly was inhibited. Further studies showed that in the absence of PFN1, Arp2/3 no longer localizes to the leading edge and Mena/VASP is non-functional. Additionally, we discovered that discrete stages of internetwork competition and collaboration between Arp2/3 and Mena/VASP networks exist at different PFN1 concentrations. Low levels of PFN1 caused filopodia to form exclusively at the leading edge, while higher concentrations inhibited filopodia and favored lamellipodia and pre-filopodia bundles. These results demonstrate that dramatic changes to actin architecture can be made simply by modifying PFN1 availability.
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Affiliation(s)
- Kristen Skruber
- Department of Anatomy and Cell Biology, University of Florida, College of Medicine, Gainesville, FL 32610, USA; Center for Translational Research in Neurodegenerative Disease, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Peyton V Warp
- Department of Anatomy and Cell Biology, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Rachael Shklyarov
- Department of Anatomy and Cell Biology, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - James D Thomas
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Jessica L Henty-Ridilla
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, NY 13210, USA
| | - Tracy-Ann Read
- Department of Anatomy and Cell Biology, University of Florida, College of Medicine, Gainesville, FL 32610, USA; Center for Translational Research in Neurodegenerative Disease, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Eric A Vitriol
- Department of Anatomy and Cell Biology, University of Florida, College of Medicine, Gainesville, FL 32610, USA; Center for Translational Research in Neurodegenerative Disease, University of Florida, College of Medicine, Gainesville, FL 32610, USA.
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18
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RIAM-VASP Module Relays Integrin Complement Receptors in Outside-In Signaling Driving Particle Engulfment. Cells 2020; 9:cells9051166. [PMID: 32397169 PMCID: PMC7291270 DOI: 10.3390/cells9051166] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/27/2020] [Accepted: 05/07/2020] [Indexed: 12/12/2022] Open
Abstract
The phagocytic integrins and complement receptors αMβ2/CR3 and αXβ2/CR4 are classically associated with the phagocytosis of iC3b-opsonized particles. The activation of this receptor is dependent on signals derived from other receptors (inside-out signaling) with the crucial involvement of the Rap1-RIAM-Talin-1 pathway. Here, we analyze the implication of RIAM and its binding partner VASP in the signaling events occurring downstream of β2 integrins (outside-in) during complement-mediated phagocytosis. To this end, we used HL-60 promyelocytic cell lines deficient in RIAM or VASP or overexpressing EGFP-tagged VASP to determine VASP dynamics at phagocytic cups. Our results indicate that RIAM-deficient HL-60 cells presented impaired particle internalization and altered integrin downstream signaling during complement-dependent phagocytosis. Similarly, VASP deficiency completely blocked phagocytosis, while VASP overexpression increased the random movement of phagocytic particles at the cell surface, with reduced internalization. Moreover, the recruitment of VASP to particle contact sites, amount of pSer157-VASP and formation of actin-rich phagocytic cups were dependent on RIAM expression. Our results suggested that RIAM worked as a relay for integrin complement receptors in outside-in signaling, coordinating integrin activation and cytoskeletal rearrangements via its interaction with VASP.
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19
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STIP1/HOP Regulates the Actin Cytoskeleton through Interactions with Actin and Changes in Actin-Binding Proteins Cofilin and Profilin. Int J Mol Sci 2020; 21:ijms21093152. [PMID: 32365744 PMCID: PMC7246624 DOI: 10.3390/ijms21093152] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/26/2020] [Accepted: 04/27/2020] [Indexed: 12/13/2022] Open
Abstract
Cell migration plays a vital role in both health and disease. It is driven by reorganization of the actin cytoskeleton, which is regulated by actin-binding proteins cofilin and profilin. Stress-inducible phosphoprotein 1 (STIP1) is a well-described co-chaperone of the Hsp90 chaperone system, and our findings identify a potential regulatory role of STIP1 in actin dynamics. We show that STIP1 can be isolated in complex with actin and Hsp90 from HEK293T cells and directly interacts with actin in vitro via the C-terminal TPR2AB-DP2 domain of STIP1, potentially due to a region spanning two putative actin-binding motifs. We found that STIP1 could stimulate the in vitro ATPase activity of actin, suggesting a potential role in the modulation of F-actin formation. Interestingly, while STIP1 depletion in HEK293T cells had no major effect on total actin levels, it led to increased nuclear accumulation of actin, disorganization of F-actin structures, and an increase and decrease in cofilin and profilin levels, respectively. This study suggests that STIP1 regulates the cytoskeleton by interacting with actin, or via regulating the ratio of proteins known to affect actin dynamics.
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20
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Blumenthal D, Burkhardt JK. Multiple actin networks coordinate mechanotransduction at the immunological synapse. J Cell Biol 2020; 219:e201911058. [PMID: 31977034 PMCID: PMC7041673 DOI: 10.1083/jcb.201911058] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/31/2019] [Accepted: 01/02/2020] [Indexed: 12/26/2022] Open
Abstract
Activation of naive T cells by antigen-presenting cells (APCs) is an essential step in mounting an adaptive immune response. It is known that antigen recognition and T cell receptor (TCR) signaling depend on forces applied by the T cell actin cytoskeleton, but until recently, the underlying mechanisms have been poorly defined. Here, we review recent advances in the field, which show that specific actin-dependent structures contribute to the process in distinct ways. In essence, T cell priming involves a tug-of-war between the cytoskeletons of the T cell and the APC, where the actin cytoskeleton serves as a mechanical intermediate that integrates force-dependent signals. We consider each of the relevant actin-rich T cell structures separately and address how they work together at the topologically and temporally complex cell-cell interface. In addition, we address how this mechanobiology can be incorporated into canonical immunological models to improve how these models explain T cell sensitivity and antigenic specificity.
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Affiliation(s)
| | - Janis K. Burkhardt
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia Research Institute and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
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21
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Abstract
Actin polymerization is essential for cells to migrate, as well as for various cell biological processes such as cytokinesis and vesicle traffic. This brief review describes the mechanisms underlying its different roles and recent advances in our understanding. Actin usually requires "nuclei"-preformed actin filaments-to start polymerizing, but, once initiated, polymerization continues constitutively. The field therefore has a strong focus on nucleators, in particular the Arp2/3 complex and formins. These have different functions, are controlled by contrasting mechanisms, and generate alternate geometries of actin networks. The Arp2/3 complex functions only when activated by nucleation-promoting factors such as WASP, Scar/WAVE, WASH, and WHAMM and when binding to a pre-existing filament. Formins can be individually active but are usually autoinhibited. Each is controlled by different mechanisms and is involved in different biological roles. We also describe the processes leading to actin disassembly and their regulation and conclude with four questions whose answers are important for understanding actin dynamics but are currently unanswered.
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Affiliation(s)
- Simona Buracco
- Institute of Cancer Sciences, University of Glasgow, Bearsden, G61 1BD, UK
| | - Sophie Claydon
- Institute of Cancer Sciences, University of Glasgow, Bearsden, G61 1BD, UK
| | - Robert Insall
- Institute of Cancer Sciences, University of Glasgow, Bearsden, G61 1BD, UK
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22
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The Cytoskeleton of the Retinal Pigment Epithelium: from Normal Aging to Age-Related Macular Degeneration. Int J Mol Sci 2019; 20:ijms20143578. [PMID: 31336621 PMCID: PMC6678077 DOI: 10.3390/ijms20143578] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/15/2019] [Accepted: 07/18/2019] [Indexed: 12/15/2022] Open
Abstract
The retinal pigment epithelium (RPE) is a unique epithelium, with major roles which are essential in the visual cycle and homeostasis of the outer retina. The RPE is a monolayer of polygonal and pigmented cells strategically placed between the neuroretina and Bruch membrane, adjacent to the fenestrated capillaries of the choriocapillaris. It shows strong apical (towards photoreceptors) to basal/basolateral (towards Bruch membrane) polarization. Multiple functions are bound to a complex structure of highly organized and polarized intracellular components: the cytoskeleton. A strong connection between the intracellular cytoskeleton and extracellular matrix is indispensable to maintaining the function of the RPE and thus, the photoreceptors. Impairments of these intracellular structures and the regular architecture they maintain often result in a disrupted cytoskeleton, which can be found in many retinal diseases, including age-related macular degeneration (AMD). This review article will give an overview of current knowledge on the molecules and proteins involved in cytoskeleton formation in cells, including RPE and how the cytoskeleton is affected under stress conditions—especially in AMD.
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23
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The Architecture of Traveling Actin Waves Revealed by Cryo-Electron Tomography. Structure 2019; 27:1211-1223.e5. [PMID: 31230946 DOI: 10.1016/j.str.2019.05.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 04/12/2019] [Accepted: 05/17/2019] [Indexed: 02/06/2023]
Abstract
Actin waves are dynamic supramolecular structures involved in cell migration, cytokinesis, adhesion, and neurogenesis. Although wave-like propagation of actin networks is a widespread phenomenon, the actin architecture underlying wave propagation remained unknown. In situ cryo-electron tomography of Dictyostelium cells unveils the wave architecture and provides evidence for wave progression by de novo actin nucleation. Subtomogram averaging reveals the structure of Arp2/3 complex-mediated branch junctions in their native state, and enables quantitative analysis of the 3D organization of branching within the waves. We find an excess of branches directed toward the substrate-attached membrane, and tent-like structures at sites of branch clustering. Fluorescence imaging shows that Arp2/3 clusters follow accumulation of the elongation factor VASP. We propose that filament growth toward the membrane lifts up the actin network as the wave propagates, until depolymerization of oblique filaments at the back causes the collapse of horizontal filaments into a compact layer.
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24
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The Cytoskeleton-A Complex Interacting Meshwork. Cells 2019; 8:cells8040362. [PMID: 31003495 PMCID: PMC6523135 DOI: 10.3390/cells8040362] [Citation(s) in RCA: 181] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/22/2022] Open
Abstract
The cytoskeleton of animal cells is one of the most complicated and functionally versatile structures, involved in processes such as endocytosis, cell division, intra-cellular transport, motility, force transmission, reaction to external forces, adhesion and preservation, and adaptation of cell shape. These functions are mediated by three classical cytoskeletal filament types, as follows: Actin, microtubules, and intermediate filaments. The named filaments form a network that is highly structured and dynamic, responding to external and internal cues with a quick reorganization that is orchestrated on the time scale of minutes and has to be tightly regulated. Especially in brain tumors, the cytoskeleton plays an important role in spreading and migration of tumor cells. As the cytoskeletal organization and regulation is complex and many-faceted, this review aims to summarize the findings about cytoskeletal filament types, including substructures formed by them, such as lamellipodia, stress fibers, and interactions between intermediate filaments, microtubules and actin. Additionally, crucial regulatory aspects of the cytoskeletal filaments and the formed substructures are discussed and integrated into the concepts of cell motility. Even though little is known about the impact of cytoskeletal alterations on the progress of glioma, a final point discussed will be the impact of established cytoskeletal alterations in the cellular behavior and invasion of glioma.
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25
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Liu L, Zhang L, Zhao S, Zhao XY, Min PX, Ma YD, Wang YY, Chen Y, Tang SJ, Zhang YJ, Du J, Gu L. Non-canonical Notch Signaling Regulates Actin Remodeling in Cell Migration by Activating PI3K/AKT/Cdc42 Pathway. Front Pharmacol 2019; 10:370. [PMID: 31057403 PMCID: PMC6477508 DOI: 10.3389/fphar.2019.00370] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 03/26/2019] [Indexed: 12/31/2022] Open
Abstract
Tumor cell migration is a critical step in cancer metastasis. Over-activated Notch pathway can promote the migration of cancer cells, especially in the breast cancer. However, the underlying mechanism of non-canonical Notch signaling in modulating the migration has not yet been clearly characterized. Here we demonstrated that DAPT, a gamma secretase inhibitor, inhibited protrusion formation and cell motility, and then reduced the migration of triple-negative breast cancer cells, through increasing the activity of Cdc42 by non-canonical Notch pathway. Phosphorylation of AKT on S473 was surprisingly increased when Notch signaling was inhibited by DAPT. Inhibition of PI3K and AKT by LY294002 and MK2206, respectively, or knockdown of AKT expression by siRNA blocked DAPT-induced activation of Cdc42. Moreover, immunofluorescence staining further showed that DAPT treatment reduced the formation of lamellipodia and induced actin cytoskeleton remodeling. Taken together, these results indicated that DAPT inhibited Notch signaling and consequently activated PI3K/AKT/Cdc42 signaling by non-canonical pathway, facilitated the formation of filopodia and inhibited the assembly of lamellipodia, and finally resulted in the decrease of migration activity of breast cancer cells.
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Affiliation(s)
- Lei Liu
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, China.,Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.,Department of Physiology, Xuzhou Medical University, Xuzhou, China
| | - Lin Zhang
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, China.,Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China
| | - Shuo Zhao
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Xu-Yang Zhao
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, China.,Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China
| | - Peng-Xiang Min
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Ya-Dong Ma
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Yue-Yuan Wang
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Yan Chen
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, China.,Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China
| | - Si-Jie Tang
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Yu-Jie Zhang
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.,Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Jun Du
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.,Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Luo Gu
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.,Department of Physiology, Nanjing Medical University, Nanjing, China
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26
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Fernández-Calleja V, Fernández-Nestosa MJ, Hernández P, Schvartzman JB, Krimer DB. CRISPR/Cas9-mediated deletion of the Wiskott-Aldrich syndrome locus causes actin cytoskeleton disorganization in murine erythroleukemia cells. PeerJ 2019; 7:e6284. [PMID: 30671311 PMCID: PMC6339507 DOI: 10.7717/peerj.6284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 12/14/2018] [Indexed: 01/18/2023] Open
Abstract
Wiskott-Aldrich syndrome (WAS) is a recessive X-linked inmmunodeficiency caused by loss-of-function mutations in the gene encoding the WAS protein (WASp). WASp plays an important role in the polymerization of the actin cytoskeleton in hematopoietic cells through activation of the Arp2/3 complex. In a previous study, we found that actin cytoskeleton proteins, including WASp, were silenced in murine erythroleukemia cells defective in differentiation. Here, we designed a CRISPR/Cas9 strategy to delete a 9.5-kb genomic region encompassing the Was gene in the X chromosome of murine erythroleukemia (MEL) cells. We show that Was-deficient MEL cells have a poor organization of the actin cytoskeleton that can be recovered by restoring Was expression. We found that whereas the total amount of actin protein was similar between wild-type and Was knockout MEL cells, the latter exhibited an altered ratio of monomeric G-actin to polymeric F-actin. We also demonstrate that Was overexpression can mediate the activation of Bruton’s tyrosine kinase. Overall, these findings support the role of WASp as a key regulator of F-actin in erythroid cells.
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Affiliation(s)
- Vanessa Fernández-Calleja
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Spanish National Research Council (CSIC), Madrid, Spain
| | | | - Pablo Hernández
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Spanish National Research Council (CSIC), Madrid, Spain
| | - Jorge B Schvartzman
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Spanish National Research Council (CSIC), Madrid, Spain
| | - Dora B Krimer
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Spanish National Research Council (CSIC), Madrid, Spain
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27
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Roy NH, Burkhardt JK. The Actin Cytoskeleton: A Mechanical Intermediate for Signal Integration at the Immunological Synapse. Front Cell Dev Biol 2018; 6:116. [PMID: 30283780 PMCID: PMC6156151 DOI: 10.3389/fcell.2018.00116] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 08/27/2018] [Indexed: 12/22/2022] Open
Abstract
The immunological synapse (IS) is a specialized structure that serves as a platform for cell-cell communication between a T cell and an antigen-presenting cell (APC). Engagement of the T cell receptor (TCR) with cognate peptide-MHC complexes on the APC activates the T cell and instructs its differentiation. Proper T cell activation also requires engagement of additional receptor-ligand pairs, which promote sustained adhesion and deliver costimulatory signals. These events are orchestrated by T cell actin dynamics, which organize IS components and facilitate their signaling. The actin network flows from the edge of the cell inward, driving the centralization of TCR microclusters and providing the force to activate the integrin LFA-1. We recently showed that engagement of LFA-1 slows actin flow, and that this affects TCR signaling. This study highlights the physical nature of the IS, and contributes to a growing appreciation in the field that mechanosensing and mechanotransduction are essential for IS function. Additionally, it is becoming clear that there are multiple types of actin structures at the IS that promote signaling in distinct ways. How the different actin structures contribute to force production and mechanotransduction is just beginning to be explored. In this Perspective, we will feature recent work from our lab and others, that collectively points toward a model in which actin dynamics drive mechanical signaling and receptor crosstalk during T cell activation.
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Affiliation(s)
- Nathan H Roy
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA, United States
| | - Janis K Burkhardt
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA, United States.,Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
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28
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Verboon JM, Decker JR, Nakamura M, Parkhurst SM. Wash exhibits context-dependent phenotypes and, along with the WASH regulatory complex, regulates Drosophila oogenesis. J Cell Sci 2018; 131:jcs.211573. [PMID: 29549166 DOI: 10.1242/jcs.211573] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 03/12/2018] [Indexed: 12/12/2022] Open
Abstract
WASH, a Wiskott-Aldrich syndrome (WAS) family protein, has many cell and developmental roles related to its function as a branched actin nucleation factor. Similar to mammalian WASHC1, which is embryonic lethal, Drosophila Wash was found to be essential for oogenesis and larval development. Recently, however, Drosophila wash was reported to be homozygous viable. Here, we verify that the original wash null allele harbors an unrelated lethal background mutation; however, this unrelated lethal mutation does not contribute to any Wash oogenesis phenotypes. Significantly, we find that: (1) the homozygous wash null allele retains partial lethality, leading to non-Mendelian inheritance; (2) the allele's functions are subject to its specific genetic background; and (3) the homozygous stock rapidly accumulates modifications that allow it to become robust. Together, these results suggest that Wash plays an important role in oogenesis via the WASH regulatory complex. Finally, we show that another WAS family protein, SCAR/WAVE, plays a similar role in oogenesis and that it is upregulated as one of the modifications that allows the wash allele to survive in the homozygous state.
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Affiliation(s)
- Jeffrey M Verboon
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA 98109
| | - Jacob R Decker
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA 98109
| | - Mitsutoshi Nakamura
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA 98109
| | - Susan M Parkhurst
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA 98109
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29
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Baudier J, Jenkins ZA, Robertson SP. The filamin-B–refilin axis – spatiotemporal regulators of the actin-cytoskeleton in development and disease. J Cell Sci 2018; 131:131/8/jcs213959. [DOI: 10.1242/jcs.213959] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
ABSTRACT
During development, cycles of spatiotemporal remodeling of higher-order networks of actin filaments contribute to control cell fate specification and differentiation. Programs for controlling these dynamics are hard-wired into actin-regulatory proteins. The filamin family of actin-binding proteins exert crucial mechanotransduction and signaling functions in tissue morphogenesis. Filamin-B (FLNB) is a key player in chondrocyte progenitor differentiation for endochondral ossification. Biallelic loss-of-function mutations or gain-of-function mutations in FLNB cause two groups of skeletal disorders that can be attributed to either the loss of repressive function on TGF-β signaling or a disruption in mechanosensory properties, respectively. In this Review, we highlight a unique family of vertebrate-specific short-lived filamin-binding proteins, the refilins (refilin-A and refilin-B), that modulate filamin-dependent actin crosslinking properties. Refilins are downstream TGF-β effectors in epithelial cells. Double knockout of both refilin-A and refilin-B in mice results in precocious ossification of some axial skeletal elements, leading to malformations that are similar to those seen in FLNB-deficient mice. Based on these findings, we present a model summarizing the role of refilins in regulating the mechanosensory functions of FLNB during skeletal development. We also discuss the possible contribution of refilins to FLNB-related skeletal pathologies that are associated with gain-of-function mutations.
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Affiliation(s)
- Jacques Baudier
- Aix Marseille Université, CNRS, IBDM, 13284 Marseille Cedex 07, France
- Institut de Biologie du Développement de Marseille-UMR CNRS 7288, Campus de Luminy-Case 907, 13288 Marseille Cedex 9, France
| | - Zandra A. Jenkins
- Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Stephen P. Robertson
- Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
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30
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Davidson AJ, Amato C, Thomason PA, Insall RH. WASP family proteins and formins compete in pseudopod- and bleb-based migration. J Cell Biol 2018; 217:701-714. [PMID: 29191847 PMCID: PMC5800805 DOI: 10.1083/jcb.201705160] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 10/03/2017] [Accepted: 11/06/2017] [Indexed: 11/24/2022] Open
Abstract
Actin pseudopods induced by SCAR/WAVE drive normal migration and chemotaxis in eukaryotic cells. Cells can also migrate using blebs, in which the edge is driven forward by hydrostatic pressure instead of actin. In Dictyostelium discoideum, loss of SCAR is compensated by WASP moving to the leading edge to generate morphologically normal pseudopods. Here we use an inducible double knockout to show that cells lacking both SCAR and WASP are unable to grow, make pseudopods or, unexpectedly, migrate using blebs. Remarkably, amounts and dynamics of actin polymerization are normal. Pseudopods are replaced in double SCAR/WASP mutants by aberrant filopods, induced by the formin dDia2. Further disruption of the gene for dDia2 restores cells' ability to initiate blebs and thus migrate, though pseudopods are still lost. Triple knockout cells still contain near-normal F-actin levels. This work shows that SCAR, WASP, and dDia2 compete for actin. Loss of SCAR and WASP causes excessive dDia2 activity, maintaining F-actin levels but blocking pseudopod and bleb formation and migration.
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Affiliation(s)
| | - Clelia Amato
- Cancer Research UK Beatson Institute, Glasgow, Scotland, UK
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31
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Carlier MF, Shekhar S. Global treadmilling coordinates actin turnover and controls the size of actin networks. Nat Rev Mol Cell Biol 2017. [PMID: 28248322 DOI: 10.1038/nrm.(2016)172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Various cellular processes (including cell motility) are driven by the regulated, polarized assembly of actin filaments into distinct force-producing arrays of defined size and architecture. Branched, linear, contractile and cytosolic arrays coexist in vivo, and cells intricately control the number, length and assembly rate of filaments in these arrays. Recent in vitro and in vivo studies have revealed novel molecular mechanisms that regulate the number of filament barbed and pointed ends and their respective assembly and disassembly rates, thus defining classes of dynamically different filaments, which coexist in the same cell. We propose that a global treadmilling process, in which a steady-state amount of polymerizable actin monomers is established by the dynamics of each network, is responsible for defining the size and turnover of coexisting actin networks. Furthermore, signal-induced changes in the partitioning of actin to distinct arrays (mediated by RHO GTPases) result in the establishment of various steady-state concentrations of polymerizable monomers, thereby globally influencing the growth rate of actin filaments.
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Affiliation(s)
- Marie-France Carlier
- Institute for Integrative Biology of the Cell (I2BC), CNRS, Gif-sur-Yvette, Paris 91190, France
| | - Shashank Shekhar
- Institute for Integrative Biology of the Cell (I2BC), CNRS, Gif-sur-Yvette, Paris 91190, France
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32
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Carlier MF, Shekhar S. Global treadmilling coordinates actin turnover and controls the size of actin networks. Nat Rev Mol Cell Biol 2017; 18:389-401. [DOI: 10.1038/nrm.2016.172] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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33
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Hatch AL, Ji WK, Merrill RA, Strack S, Higgs HN. Actin filaments as dynamic reservoirs for Drp1 recruitment. Mol Biol Cell 2016; 27:3109-3121. [PMID: 27559132 PMCID: PMC5063618 DOI: 10.1091/mbc.e16-03-0193] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 08/19/2016] [Indexed: 11/11/2022] Open
Abstract
Drp1 is a dynamin-family GTPase recruited to mitochondria and peroxisomes, where it oligomerizes and drives membrane fission. Regulation of mitochondrial Drp1 recruitment is not fully understood. We previously showed that Drp1 binds actin filaments directly, and actin polymerization is necessary for mitochondrial Drp1 oligomerization in mammals. Here we show the Drp1/actin interaction displays unusual properties that are influenced by several factors. At saturation, only a fraction Drp1 binds actin filaments, and the off-rate of actin-bound Drp1 is significantly increased by unbound Drp1. GDP and GTP accelerate and decelerate Drp1/actin binding dynamics, respectively. Actin has a biphasic effect on Drp1 GTP hydrolysis, increasing at low actin:Drp1 ratio but returning to baseline at high ratio. Drp1 also bundles filaments. Bundles have reduced dynamics but follow the same trends as single filaments. Drp1 preferentially incorporates into bundles at higher ionic strength. We measure Drp1 concentration to be ∼0.5 μM in U2OS cell cytosol, suggesting the actin-binding affinity measured here (Kd = 0.6 μM) is in the physiologically relevant range. The ability of Drp1 to bind actin filaments in a highly dynamic manner provides potential for actin filaments to serve as reservoirs of oligomerization-competent Drp1 that can be accessed for mitochondrial fission.
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Affiliation(s)
- Anna L Hatch
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755
| | - Wei-Ke Ji
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755
| | - Ronald A Merrill
- Department of Pharmacology, Carver School of Medicine, University of Iowa, Iowa City, IA 52242
| | - Stefan Strack
- Department of Pharmacology, Carver School of Medicine, University of Iowa, Iowa City, IA 52242
| | - Henry N Higgs
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755
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34
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Davidson AJ, Wood W. Unravelling the Actin Cytoskeleton: A New Competitive Edge? Trends Cell Biol 2016; 26:569-576. [PMID: 27133808 PMCID: PMC4961066 DOI: 10.1016/j.tcb.2016.04.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 03/31/2016] [Accepted: 04/04/2016] [Indexed: 12/27/2022]
Abstract
Dynamic rearrangements in the actin cytoskeleton underlie a wide range of cell behaviours, which in turn contribute to many aspects of human health including embryogenesis, cancer metastasis, wound healing, and inflammation. Precise control of the actin cytoskeleton requires the coordinated activity of a diverse set of different actin regulators. However, our current understanding of the actin cytoskeleton has focused on how individual actin regulatory pathways function in isolation from one another. Recently, competition has emerged as a means by which different actin assembly factors can influence each other's activity at the cellular level. Here such findings will be used to explore the possibility that competition within the actin cytoskeleton confers cellular plasticity and the ability to prioritise multiple conflicting stimuli. Cells maintain a dynamic actin cytoskeleton by carefully balancing the activities of a diverse collection of actin regulators. Recent findings suggest that key actin assembly factors limit one another through competition over a finite pool of G-actin. Increasing or decreasing cellular G-actin influences the type of F-actin network generated. The actin monomer binding protein profilin is responsible for proportioning how much G-actin is available to each assembly factor. Cytoskeletal competition appears universally conserved from yeast to human. Competition ensures cytoskeletal homeostasis and integration/coordination between the different actin regulatory pathways to support dynamic cell behaviour.
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Affiliation(s)
- Andrew J Davidson
- School of Cellular and Molecular Medicine, Faculty of Biomedical Sciences, Biomedical Science Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Will Wood
- School of Cellular and Molecular Medicine, Faculty of Biomedical Sciences, Biomedical Science Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK.
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