1
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Towsif EM, Miller BA, Ulrichs H, Shekhar S. Multicomponent depolymerization of actin filament pointed ends by cofilin and cyclase-associated protein depends upon filament age. Eur J Cell Biol 2024; 103:151423. [PMID: 38796920 DOI: 10.1016/j.ejcb.2024.151423] [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: 10/02/2023] [Revised: 05/18/2024] [Accepted: 05/19/2024] [Indexed: 05/29/2024] Open
Abstract
Intracellular actin networks assemble through the addition of ATP-actin subunits at the growing barbed ends of actin filaments. This is followed by "aging" of the filament via ATP hydrolysis and subsequent phosphate release. Aged ADP-actin subunits thus "treadmill" through the filament before being released back into the cytoplasmic monomer pool as a result of depolymerization at filament pointed ends. The necessity for aging before filament disassembly is reinforced by preferential binding of cofilin to aged ADP-actin subunits over newly-assembled ADP-Pi actin subunits in the filament. Consequently, investigations into how cofilin influences pointed-end depolymerization have, thus far, focused exclusively on aged ADP-actin filaments. Using microfluidics-assisted Total Internal Reflection Fluorescence (mf-TIRF) microscopy, we reveal that, similar to their effects on ADP filaments, cofilin and cyclase-associated protein (CAP) also promote pointed-end depolymerization of ADP-Pi filaments. Interestingly, the maximal rates of ADP-Pi filament depolymerization by CAP and cofilin together remain approximately 20-40 times lower than for ADP filaments. Further, we find that the promotion of ADP-Pi pointed-end depolymerization is conserved for all three mammalian cofilin isoforms. Taken together, the mechanisms presented here open the possibility of newly-assembled actin filaments being directly disassembled from their pointed-ends, thus bypassing the slow step of Pi release in the aging process.
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Affiliation(s)
- Ekram M Towsif
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322, USA
| | - Blake Andrew Miller
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322, USA
| | - Heidi Ulrichs
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322, USA
| | - Shashank Shekhar
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322, USA.
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2
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Ma Q, Surya W, He D, Yang H, Han X, Nai MH, Lim CT, Torres J, Miao Y. Spa2 remodels ADP-actin via molecular condensation under glucose starvation. Nat Commun 2024; 15:4491. [PMID: 38802374 PMCID: PMC11130202 DOI: 10.1038/s41467-024-48863-4] [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: 02/15/2023] [Accepted: 05/15/2024] [Indexed: 05/29/2024] Open
Abstract
Actin nucleotide-dependent actin remodeling is essential to orchestrate signal transduction and cell adaptation. Rapid energy starvation requires accurate and timely reorganization of the actin network. Despite distinct treadmilling mechanisms of ADP- and ATP-actin filaments, their filament structures are nearly identical. How other actin-binding proteins regulate ADP-actin filament assembly is unclear. Here, we show that Spa2 which is the polarisome scaffold protein specifically remodels ADP-actin upon energy starvation in budding yeast. Spa2 triggers ADP-actin monomer nucleation rapidly through a dimeric core of Spa2 (aa 281-535). Concurrently, the intrinsically disordered region (IDR, aa 1-281) guides Spa2 undergoing phase separation and wetting on the surface of ADP-G-actin-derived F-actin and bundles the filaments. Both ADP-actin-specific nucleation and bundling activities of Spa2 are actin D-loop dependent. The IDR and nucleation core of Spa2 are evolutionarily conserved by coexistence in the fungus kingdom, suggesting a universal adaptation mechanism in the fungal kingdom in response to glucose starvation, regulating ADP-G-actin and ADP-F-actin with high nucleotide homogeneity.
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Affiliation(s)
- Qianqian Ma
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Wahyu Surya
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Danxia He
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Hanmeng Yang
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Xiao Han
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Mui Hoon Nai
- Department of Biomedical Engineering, National University of Singapore, 117583, Singapore, Singapore
| | - Chwee Teck Lim
- Department of Biomedical Engineering, National University of Singapore, 117583, Singapore, Singapore
- Institute for Health Innovation and Technology (iHealthtech), National University of Singapore, 119276, Singapore, Singapore
| | - Jaume Torres
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore.
- Institute for Digital Molecular Analytics and Science, Nanyang Technological University, 636921, Singapore, Singapore.
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3
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Heissler SM, Chinthalapudi K. Structural and functional mechanisms of actin isoforms. FEBS J 2024. [PMID: 38779987 DOI: 10.1111/febs.17153] [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: 01/06/2024] [Revised: 04/01/2024] [Accepted: 04/23/2024] [Indexed: 05/25/2024]
Abstract
Actin is a highly conserved and fundamental protein in eukaryotes and participates in a broad spectrum of cellular functions. Cells maintain a conserved ratio of actin isoforms, with muscle and non-muscle actins representing the main actin isoforms in muscle and non-muscle cells, respectively. Actin isoforms have specific and redundant functional roles and display different biochemistries, cellular localization, and interactions with myosins and actin-binding proteins. Understanding the specific roles of actin isoforms from the structural and functional perspective is crucial for elucidating the intricacies of cytoskeletal dynamics and regulation and their implications in health and disease. Here, we review how the structure contributes to the functional mechanisms of actin isoforms with a special emphasis on the questions of how post-translational modifications and disease-linked mutations affect actin isoforms biochemistry, function, and interaction with actin-binding proteins and myosin motors.
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Affiliation(s)
- Sarah M Heissler
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Krishna Chinthalapudi
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA
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4
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Towsif EM, Miller BA, Ulrichs H, Shekhar S. Multicomponent depolymerization of actin filament pointed ends by cofilin and cyclase-associated protein depends upon filament age. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.15.589566. [PMID: 38659736 PMCID: PMC11042253 DOI: 10.1101/2024.04.15.589566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Intracellular actin networks assemble through the addition of ATP-actin subunits at the growing barbed ends of actin filaments. This is followed by "aging" of the filament via ATP hydrolysis and subsequent phosphate release. Aged ADP-actin subunits thus "treadmill" through the filament before being released back into the cytoplasmic monomer pool as a result of depolymerization at filament pointed ends. The necessity for aging before filament disassembly is reinforced by preferential binding of cofilin to aged ADP-actin subunits over newly-assembled ADP-Pi actin subunits in the filament. Consequently, investigations into how cofilin influences pointed-end depolymerization have, thus far, focused exclusively on aged ADP-actin filaments. Using microfluidics-assisted Total Internal Reflection Fluorescence (mf-TIRF) microscopy, we reveal that, similar to their effects on ADP filaments, cofilin and cyclase-associated protein (CAP) also promote pointed-end depolymerization of ADP-Pi filaments. Interestingly, the maximal rates of ADP-Pi filament depolymerization by CAP and cofilin together remain approximately 20-40 times lower than for ADP filaments. Further, we find that the promotion of ADP-Pi pointed-end depolymerization is conserved for all three mammalian cofilin isoforms. Taken together, the mechanisms presented here open the possibility of newly-assembled actin filaments being directly disassembled from their pointed-ends, thus bypassing the slow step of Pi release in the aging process.
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Affiliation(s)
- Ekram M. Towsif
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322
| | - Blake Andrew Miller
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322
| | - Heidi Ulrichs
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322
| | - Shashank Shekhar
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322
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5
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Tajvidi Safa B, Huang C, Kabla A, Yang R. Active viscoelastic models for cell and tissue mechanics. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231074. [PMID: 38660600 PMCID: PMC11040246 DOI: 10.1098/rsos.231074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 02/01/2024] [Accepted: 02/25/2024] [Indexed: 04/26/2024]
Abstract
Living cells are out of equilibrium active materials. Cell-generated forces are transmitted across the cytoskeleton network and to the extracellular environment. These active force interactions shape cellular mechanical behaviour, trigger mechano-sensing, regulate cell adaptation to the microenvironment and can affect disease outcomes. In recent years, the mechanobiology community has witnessed the emergence of many experimental and theoretical approaches to study cells as mechanically active materials. In this review, we highlight recent advancements in incorporating active characteristics of cellular behaviour at different length scales into classic viscoelastic models by either adding an active tension-generating element or adjusting the resting length of an elastic element in the model. Summarizing the two groups of approaches, we will review the formulation and application of these models to understand cellular adaptation mechanisms in response to various types of mechanical stimuli, such as the effect of extracellular matrix properties and external loadings or deformations.
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Affiliation(s)
- Bahareh Tajvidi Safa
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE68588, USA
| | - Changjin Huang
- School of Mechanical & Aerospace Engineering, Nanyang Technological University, Singapore639798, Singapore
| | - Alexandre Kabla
- Department of Engineering, University of Cambridge, CambridgeCB2 1PZ, UK
| | - Ruiguo Yang
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE68588, USA
- Department of Biomedical Engineering, Michigan State University, East Lansing, MI48824, USA
- Institute for Quantitative Health Science and Engineering (IQ), Michigan State University, East Lansing, MI48824, USA
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6
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Xu L, Cao L, Li J, Staiger CJ. Cooperative actin filament nucleation by the Arp2/3 complex and formins maintains the homeostatic cortical array in Arabidopsis epidermal cells. THE PLANT CELL 2024; 36:764-789. [PMID: 38057163 PMCID: PMC10896301 DOI: 10.1093/plcell/koad301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/17/2023] [Accepted: 11/19/2023] [Indexed: 12/08/2023]
Abstract
Precise control over how and where actin filaments are created leads to the construction of unique cytoskeletal arrays within a common cytoplasm. Actin filament nucleators are key players in this activity and include the conserved actin-related protein 2/3 (Arp2/3) complex as well as a large family of formins. In some eukaryotic cells, these nucleators compete for a common pool of actin monomers and loss of one favors the activity of the other. To test whether this mechanism is conserved, we combined the ability to image single filament dynamics in the homeostatic cortical actin array of living Arabidopsis (Arabidopsis thaliana) epidermal cells with genetic and/or small molecule inhibitor approaches to stably or acutely disrupt nucleator activity. We found that Arp2/3 mutants or acute CK-666 treatment markedly reduced the frequency of side-branched nucleation events as well as overall actin filament abundance. We also confirmed that plant formins contribute to side-branched filament nucleation in vivo. Surprisingly, simultaneous inhibition of both classes of nucleator increased overall actin filament abundance and enhanced the frequency of de novo nucleation events by an unknown mechanism. Collectively, our findings suggest that multiple actin nucleation mechanisms cooperate to generate and maintain the homeostatic cortical array of plant epidermal cells.
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Affiliation(s)
- Liyuan Xu
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Lingyan Cao
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Jiejie Li
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Christopher J Staiger
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
- EMBRIO Institute, Purdue University, West Lafayette, IN 47907, USA
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7
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Zhang Y, Xu R, Wu J, Zhang Z, Wang Y, Yang H, Zhang S. Nanopore-related cellular death through cytoskeleton depolymerization by drug-induced ROS. Talanta 2024; 268:125355. [PMID: 37952317 DOI: 10.1016/j.talanta.2023.125355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 10/12/2023] [Accepted: 10/26/2023] [Indexed: 11/14/2023]
Abstract
Prostate cancer (PCa) is a malignant tumor with a very high incidence which ranks second after lung cancer. Although there are many drugs available for the treatment of PCa, their effectiveness and anti-cancer mechanisms still need to be explored. Atomic force microscopy (AFM) could characterize minor morphological changes on cell surfaces, which provides an effective method to explore the interaction between drugs and cells at the nanometer level and further investigate the mechanisms for treating PCa. In our research, AFM visualized pore-like structures in the PC3M cell membrane after treatment with the eminent anticancer agent paclitaxel (PTX). The diameter, depth and number of these pores were in a concentration and time-dependent manner. Reactive oxygen species (ROS) was shown to depolymerize the actin cytoskeleton and make the membrane more sensitive to oxidative damage, thus inducing pore information. After pretreatment with a ROS scavenger, pore formation was prevented. AFM imaging technology provides a new evaluation method for drug-targeted therapy for cancer.
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Affiliation(s)
- Yan Zhang
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou, 350007, China
| | - Renfeng Xu
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou, 350007, China
| | - Jingjing Wu
- Department of Pathology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, 350005, China
| | - Zhenghong Zhang
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou, 350007, China
| | - Yuhuang Wang
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou, 350007, China
| | - Hongqin Yang
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou, 350007, China.
| | - Sheng Zhang
- Department of Pathology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, 350005, China.
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8
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Phillips TA, Marcotti S, Cox S, Parsons M. Imaging actin organisation and dynamics in 3D. J Cell Sci 2024; 137:jcs261389. [PMID: 38236161 PMCID: PMC10906668 DOI: 10.1242/jcs.261389] [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] [Indexed: 01/19/2024] Open
Abstract
The actin cytoskeleton plays a critical role in cell architecture and the control of fundamental processes including cell division, migration and survival. The dynamics and organisation of F-actin have been widely studied in a breadth of cell types on classical two-dimensional (2D) surfaces. Recent advances in optical microscopy have enabled interrogation of these cytoskeletal networks in cells within three-dimensional (3D) scaffolds, tissues and in vivo. Emerging studies indicate that the dimensionality experienced by cells has a profound impact on the structure and function of the cytoskeleton, with cells in 3D environments exhibiting cytoskeletal arrangements that differ to cells in 2D environments. However, the addition of a third (and fourth, with time) dimension leads to challenges in sample preparation, imaging and analysis, necessitating additional considerations to achieve the required signal-to-noise ratio and spatial and temporal resolution. Here, we summarise the current tools for imaging actin in a 3D context and highlight examples of the importance of this in understanding cytoskeletal biology and the challenges and opportunities in this domain.
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Affiliation(s)
- Thomas A. Phillips
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunts House, Guys Campus, London SE1 1UL, UK
| | - Stefania Marcotti
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunts House, Guys Campus, London SE1 1UL, UK
- Microscopy Innovation Centre, King's College London, Guys Campus, London SE1 1UL, UK
| | - Susan Cox
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunts House, Guys Campus, London SE1 1UL, UK
| | - Maddy Parsons
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunts House, Guys Campus, London SE1 1UL, UK
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9
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Chen X, Arciola JM, Lee YI, Wong PHP, Yin H, Tao Q, Jin Y, Qin X, Sweeney HL, Park H. Myo10 tail is crucial for promoting long filopodia. J Biol Chem 2024; 300:105523. [PMID: 38043799 PMCID: PMC10790087 DOI: 10.1016/j.jbc.2023.105523] [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: 07/03/2023] [Revised: 11/22/2023] [Accepted: 11/24/2023] [Indexed: 12/05/2023] Open
Abstract
Filopodia are slender cellular protrusions containing parallel actin bundles involved in environmental sensing and signaling, cell adhesion and migration, and growth cone guidance and extension. Myosin 10 (Myo10), an unconventional actin-based motor protein, was reported to induce filopodial initiation with its motor domain. However, the roles of the multifunctional tail domain of Myo10 in filopodial formation and elongation remain elusive. Herein, we generated several constructs of Myo10-full-length Myo10, Myo10 with a truncated tail (Myo10 HMM), and Myo10 containing four mutations to disrupt its coiled-coil domain (Myo10 CC mutant). We found that the truncation of the tail domain decreased filopodial formation and filopodial length, while four mutations in the coiled-coil domain disrupted the motion of Myo10 toward filopodial tips and the elongation of filopodia. Furthermore, we found that filopodia elongated through multiple elongation cycles, which was supported by the Myo10 tail. These findings suggest that Myo10 tail is crucial for promoting long filopodia.
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Affiliation(s)
- Xingxiang Chen
- Division of Life Science, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
| | | | - Young Il Lee
- Department of Pharmacology & Therapeutics, University of Florida College of Medicine, Gainesville, USA
| | - Pak Hung Philip Wong
- Department of Physics, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
| | - Haoran Yin
- Division of Life Science, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
| | - Quanqing Tao
- Department of Physics, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
| | - Yuqi Jin
- Department of Physics, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
| | - Xianan Qin
- Department of Physics, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
| | - H Lee Sweeney
- Department of Pharmacology & Therapeutics, University of Florida College of Medicine, Gainesville, USA; Myology Institute, University of Florida College of Medicine, Gainesville, Florida, USA.
| | - Hyokeun Park
- Division of Life Science, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China; Department of Physics, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China.
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10
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Goode BL, Eskin J, Shekhar S. Mechanisms of actin disassembly and turnover. J Cell Biol 2023; 222:e202309021. [PMID: 37948068 PMCID: PMC10638096 DOI: 10.1083/jcb.202309021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 10/21/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023] Open
Abstract
Cellular actin networks exhibit a wide range of sizes, shapes, and architectures tailored to their biological roles. Once assembled, these filamentous networks are either maintained in a state of polarized turnover or induced to undergo net disassembly. Further, the rates at which the networks are turned over and/or dismantled can vary greatly, from seconds to minutes to hours or even days. Here, we review the molecular machinery and mechanisms employed in cells to drive the disassembly and turnover of actin networks. In particular, we highlight recent discoveries showing that specific combinations of conserved actin disassembly-promoting proteins (cofilin, GMF, twinfilin, Srv2/CAP, coronin, AIP1, capping protein, and profilin) work in concert to debranch, sever, cap, and depolymerize actin filaments, and to recharge actin monomers for new rounds of assembly.
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Affiliation(s)
- Bruce L. Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Julian Eskin
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Shashank Shekhar
- Departments of Physics, Cell Biology and Biochemistry, Emory University, Atlanta, GA, USA
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11
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Gonzalez Rodriguez S, Wirshing AC, Goodman AL, Goode BL. Cytosolic concentrations of actin binding proteins and the implications for in vivo F-actin turnover. J Cell Biol 2023; 222:e202306036. [PMID: 37801069 PMCID: PMC10558290 DOI: 10.1083/jcb.202306036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/31/2023] [Accepted: 09/21/2023] [Indexed: 10/07/2023] Open
Abstract
Understanding how numerous actin-binding proteins (ABPs) work in concert to control the assembly, organization, and turnover of the actin cytoskeleton requires quantitative information about the levels of each component. Here, we measured the cellular concentrations of actin and the majority of the conserved ABPs in Saccharomyces cerevisiae, as well as the free (cytosolic) fractions of each ABP. The cellular concentration of actin is estimated to be 13.2 µM, with approximately two-thirds in the F-actin form and one-third in the G-actin form. Cellular concentrations of ABPs range from 12.4 to 0.85 µM (Tpm1> Pfy1> Cof1> Abp1> Srv2> Abp140> Tpm2> Aip1> Cap1/2> Crn1> Sac6> Twf1> Arp2/3> Scp1). The cytosolic fractions of all ABPs are unexpectedly high (0.6-0.9) and remain so throughout the cell cycle. Based on these numbers, we speculate that F-actin binding sites are limited in vivo, which leads to high cytosolic levels of ABPs, and in turn helps drive the rapid assembly and turnover of cellular F-actin structures.
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Affiliation(s)
- Sofia Gonzalez Rodriguez
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Alison C.E. Wirshing
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Anya L. Goodman
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
- Department of Chemistry and Biochemistry, California Polytechnic State University SLO, San Luis Obispo, CA, USA
| | - Bruce L. Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
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12
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Towsif EM, Shekhar S. Cyclase-associated protein is a pro-formin anti-capping processive depolymerase of actin barbed and pointed ends. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.30.569482. [PMID: 38076850 PMCID: PMC10705416 DOI: 10.1101/2023.11.30.569482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Cellular actin networks display distinct assembly and disassembly dynamics resulting from multicomponent reactions occurring primarily at the two ends and the sides of actin filaments [1-3]. While barbed ends are considered the hotspot of actin assembly [4], disassembly is thought to primarily occur via reactions on filament sides and pointed ends [3, 5-11]. Cyclase-associated protein (CAP) has emerged as the main protagonist of actin disassembly and remodeling - it collaborates with cofilin to increase pointed-end depolymerization by 300-fold [6, 7], promotes filament "coalescence" in presence of Abp1 [12], and accelerates nucleotide exchange to regenerate monomers for new rounds of assembly [13-15]. CAP has also been reported to enhance cofilin-mediated severing [16, 17], but these claims have since been challenged [7]. Using microfluidics-assisted three-color single-molecule imaging, we now reveal that CAP also has important functions at filament barbed ends. We reveal that CAP is a processive barbed-end depolymerase capable of tracking both ends of the filament. Each CAP binding event leads to removal of about 5,175 and 620 subunits from the barbed and pointed ends respectively. We find that the WH2 domain is essential, and the CARP domain is dispensable for barbed-end depolymerization. We show that CAP co-localizes with barbed-end bound formin and capping protein, in the process increasing residence time of formin by 10-fold and promoting dissociation of CP by 4-fold. Our barbed-end observations combined with previously reported activities of CAP at pointed ends and sides, firmly establish CAP as a key player in actin dynamics.
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Affiliation(s)
- Ekram M. Towsif
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322, USA
| | - Shashank Shekhar
- Departments of Physics, Cell biology and Biochemistry, Emory University, Atlanta, GA 30322, USA
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13
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Alimov N, Hoeprich GJ, Padrick SB, Goode BL. Cyclase-associated protein interacts with actin filament barbed ends to promote depolymerization and formin displacement. J Biol Chem 2023; 299:105367. [PMID: 37863260 PMCID: PMC10692737 DOI: 10.1016/j.jbc.2023.105367] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 10/04/2023] [Accepted: 10/12/2023] [Indexed: 10/22/2023] Open
Abstract
Cyclase-associated protein (CAP) has emerged as a central player in cellular actin turnover, but its molecular mechanisms of action are not yet fully understood. Recent studies revealed that the N terminus of CAP interacts with the pointed ends of actin filaments to accelerate depolymerization in conjunction with cofilin. Here, we use in vitro microfluidics-assisted TIRF microscopy to show that the C terminus of CAP promotes depolymerization at the opposite (barbed) ends of actin filaments. In the absence of actin monomers, full-length mouse CAP1 and C-terminal halves of CAP1 (C-CAP1) and CAP2 (C-CAP2) accelerate barbed end depolymerization. Using mutagenesis and structural modeling, we show that these activities are mediated by the WH2 and CARP domains of CAP. In addition, we observe that CAP collaborates with profilin to accelerate barbed end depolymerization and that these effects depend on their direct interaction, providing the first known example of CAP-profilin collaborative effects in regulating actin. In the presence of actin monomers, CAP1 attenuates barbed end growth and promotes formin dissociation. Overall, these findings demonstrate that CAP uses distinct domains and mechanisms to interact with opposite ends of actin filaments and drive turnover. Further, they contribute to the emerging view of actin barbed ends as sites of dynamic molecular regulation, where numerous proteins compete and cooperate with each other to tune polymer dynamics, similar to the rich complexity seen at microtubule ends.
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Affiliation(s)
- Nikita Alimov
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts, USA
| | - Gregory J Hoeprich
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts, USA
| | - Shae B Padrick
- Department of Biochemistry and Molecular Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Bruce L Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts, USA.
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14
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Kandiyoth FB, Michelot A. Reconstitution of actin-based cellular processes: Why encapsulation changes the rules. Eur J Cell Biol 2023; 102:151368. [PMID: 37922812 DOI: 10.1016/j.ejcb.2023.151368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 10/02/2023] [Accepted: 10/20/2023] [Indexed: 11/07/2023] Open
Abstract
While in vitro reconstitution of cellular processes is progressing rapidly, the encapsulation of biomimetic systems to reproduce the cellular environment is a major challenge. Here we review the difficulties, using reconstitution of processes dependent on actin polymerization as an example. Some of the problems are purely technical, due to the need for engineering strategies to encapsulate concentrated solutions in micrometer-sized compartments. However, other significant issues arise from the reduction of experimental volumes, which alters the chemical evolution of these non-equilibrium systems. Important parameters to consider for successful reconstitutions are the amount of each component, their consumption and renewal rates to guarantee their continuous availability.
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Affiliation(s)
| | - Alphée Michelot
- Aix Marseille Univ, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France.
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15
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Park J, Bird JE. The actin cytoskeleton in hair bundle development and hearing loss. Hear Res 2023; 436:108817. [PMID: 37300948 PMCID: PMC10408727 DOI: 10.1016/j.heares.2023.108817] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/18/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023]
Abstract
Inner ear hair cells assemble mechanosensitive hair bundles on their apical surface that transduce sounds and accelerations. Each hair bundle is comprised of ∼ 100 individual stereocilia that are arranged into rows of increasing height and width; their specific and precise architecture being necessary for mechanoelectrical transduction (MET). The actin cytoskeleton is fundamental to establishing this architecture, not only by forming the structural scaffold shaping each stereocilium, but also by composing rootlets and the cuticular plate that together provide a stable foundation supporting each stereocilium. In concert with the actin cytoskeleton, a large assortment of actin-binding proteins (ABPs) function to cross-link actin filaments into specific topologies, as well as control actin filament growth, severing, and capping. These processes are individually critical for sensory transduction and are all disrupted in hereditary forms of human hearing loss. In this review, we provide an overview of actin-based structures in the hair bundle and the molecules contributing to their assembly and functional properties. We also highlight recent advances in mechanisms driving stereocilia elongation and how these processes are tuned by MET.
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Affiliation(s)
- Jinho Park
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States.
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16
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Ulrichs H, Gaska I, Shekhar S. Multicomponent regulation of actin barbed end assembly by twinfilin, formin and capping protein. Nat Commun 2023; 14:3981. [PMID: 37414761 PMCID: PMC10326068 DOI: 10.1038/s41467-023-39655-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 06/22/2023] [Indexed: 07/08/2023] Open
Abstract
Cells control actin assembly by regulating reactions at actin filament barbed ends. Formins accelerate elongation, capping protein (CP) arrests growth and twinfilin promotes depolymerization at barbed ends. How these distinct activities get integrated within a shared cytoplasm is unclear. Using microfluidics-assisted TIRF microscopy, we find that formin, CP and twinfilin can simultaneously bind filament barbed ends. Three‑color, single-molecule experiments reveal that twinfilin cannot bind barbed ends occupied by formin unless CP is present. This trimeric complex is short-lived (~1 s), and results in dissociation of CP by twinfilin, promoting formin-based elongation. Thus, the depolymerase twinfilin acts as a pro-formin pro-polymerization factor when both CP and formin are present. While one twinfilin binding event is sufficient to displace CP from the barbed-end trimeric complex, ~31 twinfilin binding events are required to remove CP from a CP-capped barbed end. Our findings establish a paradigm where polymerases, depolymerases and cappers together tune actin assembly.
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Affiliation(s)
- Heidi Ulrichs
- Department of Physics, Emory University, Atlanta, GA, 30322, USA
- Department of Cell Biology, Emory University, Atlanta, GA, 30322, USA
| | - Ignas Gaska
- Department of Physics, Emory University, Atlanta, GA, 30322, USA
- Department of Cell Biology, Emory University, Atlanta, GA, 30322, USA
| | - Shashank Shekhar
- Department of Physics, Emory University, Atlanta, GA, 30322, USA.
- Department of Cell Biology, Emory University, Atlanta, GA, 30322, USA.
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17
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Salem D, Fecek RJ. Role of microtubule actin crosslinking factor 1 (MACF1) in bipolar disorder pathophysiology and potential in lithium therapeutic mechanism. Transl Psychiatry 2023; 13:221. [PMID: 37353479 DOI: 10.1038/s41398-023-02483-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 05/05/2023] [Accepted: 05/23/2023] [Indexed: 06/25/2023] Open
Abstract
Bipolar affective disorder (BPAD) are life-long disorders that account for significant morbidity in afflicted patients. The etiology of BPAD is complex, combining genetic and environmental factors to increase the risk of disease. Genetic studies have pointed toward cytoskeletal dysfunction as a potential molecular mechanism through which BPAD may arise and have implicated proteins that regulate the cytoskeleton as risk factors. Microtubule actin crosslinking factor 1 (MACF1) is a giant cytoskeletal crosslinking protein that can coordinate the different aspects of the mammalian cytoskeleton with a wide variety of actions. In this review, we seek to highlight the functions of MACF1 in the nervous system and the molecular mechanisms leading to BPAD pathogenesis. We also offer a brief perspective on MACF1 and the role it may be playing in lithium's mechanism of action in treating BPAD.
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Affiliation(s)
- Deepak Salem
- Lake Erie College of Osteopathic Medicine at Seton Hill, Department of Microbiology, Greensburg, USA
- University of Maryland Medical Center/Sheppard Pratt Psychiatry Residency Program, Baltimore, USA
| | - Ronald J Fecek
- Lake Erie College of Osteopathic Medicine at Seton Hill, Department of Microbiology, Greensburg, USA.
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18
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Li M, Peng D, Cao H, Yang X, Li S, Qiu HJ, Li LF. The Host Cytoskeleton Functions as a Pleiotropic Scaffold: Orchestrating Regulation of the Viral Life Cycle and Mediating Host Antiviral Innate Immune Responses. Viruses 2023; 15:1354. [PMID: 37376653 DOI: 10.3390/v15061354] [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: 05/16/2023] [Revised: 06/08/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Viruses are obligate intracellular parasites that critically depend on their hosts to initiate infection, complete replication cycles, and generate new progeny virions. To achieve these goals, viruses have evolved numerous elegant strategies to subvert and utilize different cellular machinery. The cytoskeleton is often one of the first components to be hijacked as it provides a convenient transport system for viruses to enter the cell and reach the site of replication. The cytoskeleton is an intricate network involved in controlling the cell shape, cargo transport, signal transduction, and cell division. The host cytoskeleton has complex interactions with viruses during the viral life cycle, as well as cell-to-cell transmission once the life cycle is completed. Additionally, the host also develops unique, cytoskeleton-mediated antiviral innate immune responses. These processes are also involved in pathological damages, although the comprehensive mechanisms remain elusive. In this review, we briefly summarize the functions of some prominent viruses in inducing or hijacking cytoskeletal structures and the related antiviral responses in order to provide new insights into the crosstalk between the cytoskeleton and viruses, which may contribute to the design of novel antivirals targeting the cytoskeleton.
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Affiliation(s)
- Meilin Li
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Dingkun Peng
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Hongwei Cao
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Xiaoke Yang
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Su Li
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Hua-Ji Qiu
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Lian-Feng Li
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
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19
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Ulrichs H, Gaska I, Shekhar S. Multicomponent regulation of actin barbed end assembly by twinfilin, formin and capping protein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.24.538010. [PMID: 37163095 PMCID: PMC10168238 DOI: 10.1101/2023.04.24.538010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Living cells assemble their actin networks by regulating reactions at the barbed end of actin filaments. Formins accelerate elongation, capping protein (CP) arrests growth and twinfilin promotes depolymerization at barbed ends. How cells integrate these disparate activities within a shared cytoplasm to produce diverse actin networks, each with distinct morphologies and finely tuned assembly kinetics, is unclear. We used microfluidics-assisted TIRF microscopy to investigate how formin mDia1, CP and twinfilin influence the elongation of actin filament barbed ends. We discovered that the three proteins can simultaneously bind a barbed end in a multiprotein complex. Three-color single molecule experiments showed that twinfilin cannot bind actin filament ends occupied by formin mDia1 unless CP is present. The trimeric complex is short-lived (∼1s) and results in rapid dissociation of CP by twinfilin causing resumption of rapid formin- based elongation. Thus, the depolymerase twinfilin acts as a pro-formin factor that promotes polymerization when both CP and formin are present. While a single twinfilin binding event is sufficient to displace CP from the trimeric complex, it takes about 30 independent twinfilin binding events to remove capping protein from CP-bound barbed end. Our findings establish a new paradigm in which polymerases, depolymerases and cappers work in concert to tune cellular actin assembly.
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Affiliation(s)
- Heidi Ulrichs
- Department of Physics, Emory University, Atlanta, GA 30322
- Department of Cell Biology, Emory University, Atlanta, GA 30322
| | - Ignas Gaska
- Department of Physics, Emory University, Atlanta, GA 30322
- Department of Cell Biology, Emory University, Atlanta, GA 30322
| | - Shashank Shekhar
- Department of Physics, Emory University, Atlanta, GA 30322
- Department of Cell Biology, Emory University, Atlanta, GA 30322
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20
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Jeruzalska E, Mazur AJ. The Role of non-muscle actin paralogs in cell cycle progression and proliferation. Eur J Cell Biol 2023; 102:151315. [PMID: 37099935 DOI: 10.1016/j.ejcb.2023.151315] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 04/14/2023] [Accepted: 04/17/2023] [Indexed: 04/28/2023] Open
Abstract
Uncontrolled cell proliferation leads to several pathologies, including cancer. Thus, this process must be tightly regulated. The cell cycle accounts for cell proliferation, and its progression is coordinated with changes in cell shape, for which cytoskeleton reorganization is responsible. Rearrangement of the cytoskeleton allows for its participation in the precise division of genetic material and cytokinesis. One of the main cytoskeletal components is filamentous actin-based structures. Mammalian cells have at least six actin paralogs, four of which are muscle-specific, while two, named β- and γ-actin, are abundantly present in all types of cells. This review summarizes the findings that establish the role of non-muscle actin paralogs in regulating cell cycle progression and proliferation. We discuss studies showing that the level of a given non-muscle actin paralog in a cell influences the cell's ability to progress through the cell cycle and, thus, proliferation. Moreover, we elaborate on the non-muscle actins' role in regulating gene transcription, interactions of actin paralogs with proteins involved in controlling cell proliferation, and the contribution of non-muscle actins to different structures in a dividing cell. The data cited in this review show that non-muscle actins regulate the cell cycle and proliferation through varying mechanisms. We point to the need for further studies addressing these mechanisms.
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Affiliation(s)
- Estera Jeruzalska
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Poland
| | - Antonina J Mazur
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Poland.
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21
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Actin polymerisation and crosslinking drive left-right asymmetry in single cell and cell collectives. Nat Commun 2023; 14:776. [PMID: 36774346 PMCID: PMC9922260 DOI: 10.1038/s41467-023-35918-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/06/2023] [Indexed: 02/13/2023] Open
Abstract
Deviations from mirror symmetry in the development of bilateral organisms are common but the mechanisms of initial symmetry breaking are insufficiently understood. The actin cytoskeleton of individual cells self-organises in a chiral manner, but the molecular players involved remain essentially unidentified and the relationship between chirality of an individual cell and cell collectives is unclear. Here, we analysed self-organisation of the chiral actin cytoskeleton in individual cells on circular or elliptical patterns, and collective cell alignment in confined microcultures. Screening based on deep-learning analysis of actin patterns identified actin polymerisation regulators, depletion of which suppresses chirality (mDia1) or reverses chirality direction (profilin1 and CapZβ). The reversed chirality is mDia1-independent but requires the function of actin-crosslinker α-actinin1. A robust correlation between the effects of a variety of actin assembly regulators on chirality of individual cells and cell collectives is revealed. Thus, actin-driven cell chirality may underlie tissue and organ asymmetry.
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22
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Aufderhorst-Roberts A, Staykova M. Scratching beyond the surface - minimal actin assemblies as tools to elucidate mechanical reinforcement and shape change. Emerg Top Life Sci 2022; 6:ETLS20220052. [PMID: 36541184 PMCID: PMC9788373 DOI: 10.1042/etls20220052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022]
Abstract
The interaction between the actin cytoskeleton and the plasma membrane in eukaryotic cells is integral to a large number of functions such as shape change, mechanical reinforcement and contraction. These phenomena are driven by the architectural regulation of a thin actin network, directly beneath the membrane through interactions with a variety of binding proteins, membrane anchoring proteins and molecular motors. An increasingly common approach to understanding the mechanisms that drive these processes is to build model systems from reconstituted lipids, actin filaments and associated actin-binding proteins. Here we review recent progress in this field, with a particular emphasis on how the actin cytoskeleton provides mechanical reinforcement, drives shape change and induces contraction. Finally, we discuss potential future developments in the field, which would allow the extension of these techniques to more complex cellular processes.
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Affiliation(s)
| | - Margarita Staykova
- Centre for Materials Physics, Department of Physics, Durham University, Durham DH1 3LE, U.K
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23
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Wang L, Lin Z, Carli J, Gladala‐Kostarz A, Davies JM, Franklin‐Tong VE, Bosch M. Depletion plays a pivotal role in self-incompatibility, revealing a link between cellular energy status, cytosolic acidification and actin remodelling in pollen tubes. THE NEW PHYTOLOGIST 2022; 236:1691-1707. [PMID: 35775998 PMCID: PMC9796540 DOI: 10.1111/nph.18350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 06/15/2022] [Indexed: 06/08/2023]
Abstract
Self-incompatibility (SI) involves specific interactions during pollination to reject incompatible ('self') pollen, preventing inbreeding in angiosperms. A key event observed in pollen undergoing the Papaver rhoeas SI response is the formation of punctate F-actin foci. Pollen tube growth is heavily energy-dependent, yet ATP levels in pollen tubes have not been directly measured during SI. Here we used transgenic Arabidopsis lines expressing the Papaver pollen S-determinant to investigate a possible link between ATP levels, cytosolic pH ([pH]cyt ) and alterations to the actin cytoskeleton. We identify for the first time that SI triggers a rapid and significant ATP depletion in pollen tubes. Artificial depletion of ATP triggered cytosolic acidification and formation of actin aggregates. We also identify in vivo, evidence for a threshold [pH]cyt of 5.8 for actin foci formation. Imaging revealed that SI stimulates acidic cytosolic patches adjacent to the plasma membrane. In conclusion, this study provides evidence that ATP depletion plays a pivotal role in SI upstream of programmed cell death and reveals a link between the cellular energy status, cytosolic acidification and alterations to the actin cytoskeleton in regulating Papaver SI in pollen tubes.
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Affiliation(s)
- Ludi Wang
- Institute of Biological, Environmental and Rural Sciences (IBERS)Aberystwyth UniversityPlas GogerddanAberystwythSY23 3EEUK
| | - Zongcheng Lin
- Key Laboratory of Horticultural Plant BiologyHuazhong Agricultural UniversityWuhan430070China
| | - José Carli
- Institute of Biological, Environmental and Rural Sciences (IBERS)Aberystwyth UniversityPlas GogerddanAberystwythSY23 3EEUK
| | - Agnieszka Gladala‐Kostarz
- Institute of Biological, Environmental and Rural Sciences (IBERS)Aberystwyth UniversityPlas GogerddanAberystwythSY23 3EEUK
| | - Julia M. Davies
- Department of Plant SciencesUniversity of CambridgeCambridgeCB2 3EAUK
| | - Vernonica E. Franklin‐Tong
- School of Biosciences, College of Life and Environmental SciencesUniversity of BirminghamEdgbastonBirminghamB15 2TTUK
| | - Maurice Bosch
- Institute of Biological, Environmental and Rural Sciences (IBERS)Aberystwyth UniversityPlas GogerddanAberystwythSY23 3EEUK
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24
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Molina-Pelayo C, Olguin P, Mlodzik M, Glavic A. The conserved Pelado/ZSWIM8 protein regulates actin dynamics by promoting linear actin filament polymerization. Life Sci Alliance 2022; 5:5/12/e202201484. [PMID: 35940847 PMCID: PMC9375228 DOI: 10.26508/lsa.202201484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/15/2022] [Accepted: 07/18/2022] [Indexed: 11/24/2022] Open
Abstract
Actin filament polymerization can be branched or linear, which depends on the associated regulatory proteins. Competition for actin monomers occurs between proteins that induce branched or linear actin polymerization. Cell specialization requires the regulation of actin filaments to allow the formation of cell type-specific structures, like cuticular hairs in Drosophila, formed by linear actin filaments. Here, we report the functional analysis of CG34401/pelado, a gene encoding a SWIM domain-containing protein, conserved throughout the animal kingdom, called ZSWIM8 in mammals. Mutant pelado epithelial cells display actin hair elongation defects. This phenotype is reversed by increasing actin monomer levels or by either pushing linear actin polymerization or reducing branched actin polymerization. Similarly, in hemocytes, Pelado is essential to induce filopodia, a linear actin-based structure. We further show that this function of Pelado/ZSWIM8 is conserved in human cells, where Pelado inhibits branched actin polymerization in a cell migration context. In summary, our data indicate that the function of Pelado/ZSWIM8 in regulating actin cytoskeletal dynamics is conserved, favoring linear actin polymerization at the expense of branched filaments.
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Affiliation(s)
- Claudia Molina-Pelayo
- Department of Cell, Developmental, and Regenerative Biology, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Departamento de Biología, Centro FONDAP de Regulación del Genoma, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Patricio Olguin
- Department of Cell, Developmental, and Regenerative Biology, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA .,Departamento de Neurociencia, Programa de Genética Humana, Instituto de Ciencias Biomédicas, Instituto de Neurociencia Biomédica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Marek Mlodzik
- Department of Cell, Developmental, and Regenerative Biology, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Alvaro Glavic
- Departamento de Biología, Centro FONDAP de Regulación del Genoma, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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25
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Chen B, Wang M, Qiu J, Liao K, Zhang W, Lv Q, Ma C, Qian Z, Shi Z, Liang R, Lin Y, Ye J, Qiu Y, Lin Y. Cleavage of tropomodulin-3 by asparagine endopeptidase promotes cancer malignancy by actin remodeling and SND1/RhoA signaling. J Exp Clin Cancer Res 2022; 41:209. [PMID: 35765111 PMCID: PMC9238189 DOI: 10.1186/s13046-022-02411-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 06/07/2022] [Indexed: 12/12/2022] Open
Abstract
Abstract
Background
Abnormal proliferation and migration of cells are hallmarks of cancer initiation and malignancy. Asparagine endopeptidase (AEP) has specific substrate cleavage ability and plays a pro-cancer role in a variety of cancers. However, the underlying mechanism of AEP in cancer proliferation and migration still remains unclear.
Methods
Co-immunoprecipitation and following mass spectrometry were used to identify the substrate of AEP. Western blotting was applied to measure the expression of proteins. Single cell/nuclear-sequences were done to detect the heterogeneous expression of Tmod3 in tumor tissues. CCK-8 assay, flow cytometry assays, colony formation assay, Transwell assay and scratch wound-healing assay were performed as cellular functional experiments. Mouse intracranial xenograft tumors were studied in in vivo experiments.
Results
Here we showed that AEP cleaved a ubiquitous cytoskeleton regulatory protein, tropomodulin-3 (Tmod3) at asparagine 157 (N157) and produced two functional truncations (tTmod3-N and tTmod3-C). Truncated Tmod3 was detected in diverse tumors and was found to be associated with poor prognosis of high-grade glioma. Functional studies showed that tTmod3-N and tTmod3-C enhanced cancer cell migration and proliferation, respectively. Animal models further revealed the tumor-promoting effects of AEP truncated Tmod3 in vivo. Mechanistically, tTmod3-N was enriched in the cell cortex and competitively inhibited the pointed-end capping effect of wild-type Tmod3 on filamentous actin (F-actin), leading to actin remodeling. tTmod3-C translocated to the nucleus, where it interacted with Staphylococcal Nuclease And Tudor Domain Containing 1 (SND1), facilitating the transcription of Ras Homolog Family Member A/Cyclin Dependent Kinases (RhoA/CDKs).
Conclusion
The newly identified AEP-Tmod3 protease signaling axis is a novel “dual-regulation” mechanism of tumor cell proliferation and migration. Our work provides new clues to the underlying mechanisms of cancer proliferation and invasive progression and evidence for targeting AEP or Tmod3 for therapy.
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26
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Schutt CE, Karlén M, Karlsson R. A structural model of the profilin-formin pacemaker system for actin filament elongation. Sci Rep 2022; 12:20515. [PMID: 36443454 PMCID: PMC9705415 DOI: 10.1038/s41598-022-25011-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
The formins constitute a large class of multi-domain polymerases that catalyze the localization and growth of unbranched actin filaments in cells from yeast to mammals. The conserved FH2 domains form dimers that bind actin at the barbed end of growing filaments and remain attached as new subunits are added. Profilin-actin is recruited and delivered to the barbed end by formin FH1 domains via the binding of profilin to interspersed tracts of poly-L-proline. We present a structural model showing that profilin-actin can bind the FH2 dimer at the barbed end stabilizing a state where profilin prevents its associated actin subunit from directly joining the barbed end. It is only with the dissociation of profilin from the polymerase that an actin subunit rotates and docks into its helical position, consistent with observations that under physiological conditions optimal elongation rates depend on the dissociation rate of profilin, independently of cellular concentrations of actin subunits.
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Affiliation(s)
- Clarence E. Schutt
- grid.16750.350000 0001 2097 5006Department of Chemistry, Princeton University, Princeton, NJ USA
| | | | - Roger Karlsson
- Department of Molecular Biosciences, WGI, Stockholm University, Stockholm, Sweden.
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27
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Kudryashova E, Ankita, Ulrichs H, Shekhar S, Kudryashov DS. Pointed-end processive elongation of actin filaments by Vibrio effectors VopF and VopL. SCIENCE ADVANCES 2022; 8:eadc9239. [PMID: 36399577 PMCID: PMC9674292 DOI: 10.1126/sciadv.adc9239] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/03/2022] [Indexed: 07/20/2023]
Abstract
According to the cellular actin dynamics paradigm, filaments grow at their barbed ends and depolymerize predominantly from their pointed ends to form polar structures and do productive work. We show that actin can elongate at the pointed end when assisted by Vibrio VopF/L toxins, which act as processive polymerases. In cells, processively moving VopF/L speckles are inhibited by factors blocking the pointed but not barbed ends. Multispectral single-molecule imaging confirmed that VopF molecules associate with the pointed end, actively promoting its elongation even in the presence of profilin. Consequently, VopF/L can break the actin cytoskeleton's polarity by compromising actin-based cellular processes. Therefore, actin filament design allows processive growth at both ends, which suggests unforeseen possibilities for cellular actin organization, particularly in specialized cells and compartments.
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Affiliation(s)
- Elena Kudryashova
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Ankita
- Department of Physics, Emory University, Atlanta, GA 30322, USA
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA
| | - Heidi Ulrichs
- Department of Physics, Emory University, Atlanta, GA 30322, USA
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA
| | - Shashank Shekhar
- Department of Physics, Emory University, Atlanta, GA 30322, USA
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA
| | - Dmitri S. Kudryashov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
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28
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Fujii S. Plant physiology: ATP at the center of self-recognition. Curr Biol 2022; 32:R962-R964. [PMID: 36167047 DOI: 10.1016/j.cub.2022.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
ATP acts as the common currency of metabolic activity in all life forms. A recent study uses inter-specific transfer of the self-recognition module in plants to enable live monitoring of the cellular status in vivo, revealing the pivotal role of ATP in signaling.
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Affiliation(s)
- Sota Fujii
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan; Suntory Rising Stars Encouragement Program in Life Sciences (SunRiSE).
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29
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Wang J, Fan Y, Mittal B, Sanger JM, Sanger JW. Comparison of incorporation of wild type and mutated actins into sarcomeres in skeletal muscle cells: A fluorescence recovery after photobleaching study. Cytoskeleton (Hoboken) 2022; 79:105-115. [PMID: 36085566 DOI: 10.1002/cm.21725] [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: 06/08/2022] [Revised: 08/11/2022] [Accepted: 08/31/2022] [Indexed: 01/30/2023]
Abstract
The α-actin mutation G15R in the nucleotide-binding pocket of skeletal muscle, causes severe actin myopathy in human skeletal muscles. Expressed in cultured embryonic quail skeletal myotubes, YFP-G15R-α-actin incorporates in sarcomeres in a pattern indistinguishable from wildtype YFP-α-actin. However, patches of YFP-G15R-α-actin form, resembling those in patients. Analyses with FRAP of incorporation of YFP-G15R-α-actin showed major differences between fast-exchanging plus ends of overlapping actin filaments in Z-bands, versus slow exchanging ends of overlapping thin filaments in the middle of sarcomeres. Wildtype skeletal muscle YFP-α-actin shows a faster rate of incorporation at plus ends of F-actin than at their minus ends. Incorporation of YFP-G15R-α-actin molecules is reduced at plus ends, increased at minus ends. The same relationship of wildtype YFP-α-actin incorporation is seen in myofibrils treated with cytochalasin-D: decreased dynamics at plus ends, increased dynamics at minus ends, and F-actin aggregates. Speculation: imbalance of normal polarized assembly of F-actin creates excess monomers that form F-actin aggregates. Two other severe skeletal muscle YFP-α-actin mutations (H40Y and V163L) not in the nucleotide pocket do not affect actin dynamics, and lack F-actin aggregates. These results indicate that normal α-actin plus and minus end dynamics are needed to maintain actin filament stability, and avoid F-actin patches.
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Affiliation(s)
- Jushuo Wang
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Yingli Fan
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Balraj Mittal
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Jean M Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Joseph W Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, USA
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30
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Holz D, Hall AR, Usukura E, Yamashiro S, Watanabe N, Vavylonis D. A mechanism with severing near barbed ends andannealing explains structure and dynamics of dendriticactin networks. eLife 2022; 11:69031. [PMID: 35670664 PMCID: PMC9252579 DOI: 10.7554/elife.69031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/04/2022] [Indexed: 11/13/2022] Open
Abstract
Single molecule imaging has shown that part of actin disassembles within a few seconds after incorporation into the dendritic filament network in lamellipodia, suggestive of frequent destabilization near barbed ends. To investigate the mechanisms behind network remodeling, we created a stochastic model with polymerization, depolymerization, branching, capping, uncapping, severing, oligomer diffusion, annealing, and debranching. We find that filament severing, enhanced near barbed ends, can explain the single molecule actin lifetime distribution, if oligomer fragments reanneal to free ends with rate constants comparable to in vitro measurements. The same mechanism leads to actin networks consistent with measured filament, end, and branch concentrations. These networks undergo structural remodeling, leading to longer filaments away from the leading edge, at the +/- 35𝑜 orientation pattern. Imaging of actin speckle lifetimes at sub-second resolution verifies frequent disassembly of newly-assembled actin. We thus propose a unified mechanism that fits a diverse set of basic lamellipodia phenomenology.
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Affiliation(s)
| | | | - Eiji Usukura
- Laboratory of Single-Molecule Cell Biology, Kyoto University
| | | | - Naoki Watanabe
- Laboratory of Single-Molecule Cell Biology, Kyoto University
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31
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Moore RP, Fogerson SM, Tulu US, Yu JW, Cox AH, Sican MA, Li D, Legant WR, Weigel AV, Crawford JM, Betzig E, Kiehart DP. Super-resolution microscopy reveals actomyosin dynamics in medioapical arrays. Mol Biol Cell 2022; 33:ar94. [PMID: 35544300 DOI: 10.1091/mbc.e21-11-0537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Arrays of actin filaments (F-actin) near the apical surface of epithelial cells (medioapical arrays) contribute to apical constriction and morphogenesis throughout phylogeny. Here, super-resolution approaches (grazing incidence structured illumination, GI-SIM and lattice light sheet, LLSM) microscopy resolve individual, fluorescently labeled F-actin and bipolar myosin filaments that drive amnioserosa cell shape changes during dorsal closure in Drosophila. In expanded cells, F-actin and myosin form loose, apically domed meshworks at the plasma membrane. The arrays condense as cells contract, drawing the domes into the plane of the junctional belts. As condensation continues, individual filaments are no longer uniformly apparent. As cells expand, arrays of actomyosin are again resolved - some F-actin turnover likely occurs, but a large fraction of existing filaments rearrange. In morphologically isotropic cells, actin filaments are randomly oriented and during contraction, are drawn together but remain essentially randomly oriented. In anisotropic cells, largely parallel actin filaments are drawn closer to one another. Our images offer unparalleled resolution of F-actin in embryonic tissue show that medioapical arrays are tightly apposed to the plasma membrane, are continuous with meshworks of lamellar F-actin and thereby constitute modified cell cortex. In concert with other tagged array components, super-resolution imaging of live specimens will offer new understanding of cortical architecture and function. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text].
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Affiliation(s)
- Regan P Moore
- Biology Department, Duke University, Durham, NC, 27708, USA.,Department of Pharmacology, University of North Carolina, Chapel Hill, NC, 27599, USA.,Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, 27599, USA and North Carolina State University, Raleigh, NC, 27695, USA
| | | | - U Serdar Tulu
- Biology Department, Duke University, Durham, NC, 27708, USA
| | - Jason W Yu
- Biology Department, Duke University, Durham, NC, 27708, USA
| | - Amanda H Cox
- Biology Department, Duke University, Durham, NC, 27708, USA
| | | | - Dong Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Wesley R Legant
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, 27599, USA.,Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, 27599, USA and North Carolina State University, Raleigh, NC, 27695, USA
| | - Aubrey V Weigel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA
| | | | - Eric Betzig
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA.,Departments of Physics and Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
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32
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Sen B, Xie Z, Howard S, Styner M, van Wijnen AJ, Uzer G, Rubin J. Mechanically Induced Nuclear Shuttling of β-Catenin Requires Co-transfer of Actin. Stem Cells 2022; 40:423-434. [PMID: 35278073 PMCID: PMC9633329 DOI: 10.1093/stmcls/sxac006] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 01/27/2022] [Indexed: 11/15/2022]
Abstract
Mesenchymal stem cells (MSCs) respond to environmental forces with both cytoskeletal re-structuring and activation of protein chaperones of mechanical information, β-catenin, and yes-associated protein 1 (YAP1). To function, MSCs must differentiate between dynamic forces such as cyclic strains of extracellular matrix due to physical activity and static strains due to ECM stiffening. To delineate how MSCs recognize and respond differently to both force types, we compared effects of dynamic (200 cycles × 2%) and static (1 × 2% hold) strain on nuclear translocation of β-catenin and YAP1 at 3 hours after force application. Dynamic strain induced nuclear accumulation of β-catenin, and increased cytoskeletal actin structure and cell stiffness, but had no effect on nuclear YAP1 levels. Critically, both nuclear actin and nuclear stiffness increased along with dynamic strain-induced β-catenin transport. Augmentation of cytoskeletal structure using either static strain or lysophosphatidic acid did not increase nuclear content of β-catenin or actin, but induced robust nuclear increase in YAP1. As actin binds β-catenin, we considered whether β-catenin, which lacks a nuclear localization signal, was dependent on actin to gain entry to the nucleus. Knockdown of cofilin-1 (Cfl1) or importin-9 (Ipo9), which co-mediate nuclear transfer of G-actin, prevented dynamic strain-mediated nuclear transfer of both β-catenin and actin. In sum, dynamic strain induction of actin re-structuring promotes nuclear transport of G-actin, concurrently supporting nuclear access of β-catenin via mechanisms used for actin transport. Thus, dynamic and static strain activate alternative mechanoresponses reflected by differences in the cellular distributions of actin, β-catenin, and YAP1.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Sean Howard
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Andre J van Wijnen
- Department of Biochemistry, University of Vermont Medical School, Burlington, VT, USA
| | - Gunes Uzer
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Janet Rubin
- Corresponding author: Janet Rubin, Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA.
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33
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Romani P, Nirchio N, Arboit M, Barbieri V, Tosi A, Michielin F, Shibuya S, Benoist T, Wu D, Hindmarch CCT, Giomo M, Urciuolo A, Giamogante F, Roveri A, Chakravarty P, Montagner M, Calì T, Elvassore N, Archer SL, De Coppi P, Rosato A, Martello G, Dupont S. Mitochondrial fission links ECM mechanotransduction to metabolic redox homeostasis and metastatic chemotherapy resistance. Nat Cell Biol 2022; 24:168-180. [PMID: 35165418 PMCID: PMC7615745 DOI: 10.1038/s41556-022-00843-w] [Citation(s) in RCA: 63] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 01/06/2022] [Indexed: 01/07/2023]
Abstract
Metastatic breast cancer cells disseminate to organs with a soft microenvironment. Whether and how the mechanical properties of the local tissue influence their response to treatment remains unclear. Here we found that a soft extracellular matrix empowers redox homeostasis. Cells cultured on a soft extracellular matrix display increased peri-mitochondrial F-actin, promoted by Spire1C and Arp2/3 nucleation factors, and increased DRP1- and MIEF1/2-dependent mitochondrial fission. Changes in mitochondrial dynamics lead to increased production of mitochondrial reactive oxygen species and activate the NRF2 antioxidant transcriptional response, including increased cystine uptake and glutathione metabolism. This retrograde response endows cells with resistance to oxidative stress and reactive oxygen species-dependent chemotherapy drugs. This is relevant in a mouse model of metastatic breast cancer cells dormant in the lung soft tissue, where inhibition of DRP1 and NRF2 restored cisplatin sensitivity and prevented disseminated cancer-cell awakening. We propose that targeting this mitochondrial dynamics- and redox-based mechanotransduction pathway could open avenues to prevent metastatic relapse.
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Affiliation(s)
- Patrizia Romani
- Department of Molecular Medicine (DMM), University of Padua, Padua, Italy
| | - Nunzia Nirchio
- Department of Molecular Medicine (DMM), University of Padua, Padua, Italy
| | - Mattia Arboit
- Department of Biology (DiBio), University of Padua, Padua, Italy
| | - Vito Barbieri
- Department of Surgery, Oncology and Gastroenterology (DiSCOG), University of Padua, Padua, Italy
- Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Anna Tosi
- Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Federica Michielin
- Institute of Child Health, NIHR Biomedical Research Centre, Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Soichi Shibuya
- Institute of Child Health, NIHR Biomedical Research Centre, Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Thomas Benoist
- Institute of Child Health, NIHR Biomedical Research Centre, Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Danchen Wu
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | | | - Monica Giomo
- Department of Industrial Engineering (DII), University of Padua, Padua, Italy
- Venetian Institute of Molecular Medicine (VIMM), Padua, Italy
| | - Anna Urciuolo
- Department of Molecular Medicine (DMM), University of Padua, Padua, Italy
- Fondazione Istituto di Ricerca Pediatrica (IRP), Città della Speranza, Padua, Italy
| | - Flavia Giamogante
- Department of Biomedical Sciences (DSB), University of Padua, Padua, Italy
| | - Antonella Roveri
- Department of Molecular Medicine (DMM), University of Padua, Padua, Italy
| | | | - Marco Montagner
- Department of Molecular Medicine (DMM), University of Padua, Padua, Italy
| | - Tito Calì
- Department of Biomedical Sciences (DSB), University of Padua, Padua, Italy
| | - Nicola Elvassore
- Institute of Child Health, NIHR Biomedical Research Centre, Great Ormond Street Institute of Child Health, UCL, London, UK
- Department of Industrial Engineering (DII), University of Padua, Padua, Italy
- Venetian Institute of Molecular Medicine (VIMM), Padua, Italy
| | - Stephen L Archer
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Paolo De Coppi
- Institute of Child Health, NIHR Biomedical Research Centre, Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Antonio Rosato
- Department of Surgery, Oncology and Gastroenterology (DiSCOG), University of Padua, Padua, Italy
- Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | | | - Sirio Dupont
- Department of Molecular Medicine (DMM), University of Padua, Padua, Italy.
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34
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Bourdais A, Dehapiot B, Halet G. Cofilin regulates actin network homeostasis and microvilli length in mouse oocytes. J Cell Sci 2021; 134:273797. [PMID: 34841429 DOI: 10.1242/jcs.259237] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/18/2021] [Indexed: 11/20/2022] Open
Abstract
How multiple actin networks coexist in a common cytoplasm while competing for a shared pool of monomers is still an ongoing question. This is exemplified by meiotic maturation in the mouse oocyte, which relies on the dynamic remodeling of distinct cortical and cytoplasmic F-actin networks. Here, we show that the conserved actin-depolymerizing factor cofilin is activated in a switch-like manner upon meiosis resumption from prophase arrest. Interfering with cofilin activation during maturation resulted in widespread elongation of microvilli, while cytoplasmic F-actin was depleted, leading to defects in spindle migration and polar body extrusion. In contrast, cofilin inactivation in metaphase II-arrested oocytes resulted in a shutdown of F-actin dynamics, along with a dramatic overgrowth of the polarized actin cap. However, inhibition of the Arp2/3 complex to promote actin cap disassembly elicited ectopic microvilli outgrowth in the polarized cortex. These data establish cofilin as a key player in actin network homeostasis in oocytes and reveal that microvilli can act as a sink for monomers upon disassembly of a competing network.
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Affiliation(s)
- Anne Bourdais
- Institut Génétique et Développement de Rennes , CNRS IGDR UMR 6290, Université de Rennes 1, F-35000 Rennes, France
| | - Benoit Dehapiot
- Institut Génétique et Développement de Rennes , CNRS IGDR UMR 6290, Université de Rennes 1, F-35000 Rennes, France
| | - Guillaume Halet
- Institut Génétique et Développement de Rennes , CNRS IGDR UMR 6290, Université de Rennes 1, F-35000 Rennes, France
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35
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Saito N, Sawai S. Three-dimensional morphodynamic simulations of macropinocytic cups. iScience 2021; 24:103087. [PMID: 34755081 PMCID: PMC8560551 DOI: 10.1016/j.isci.2021.103087] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/13/2021] [Accepted: 09/01/2021] [Indexed: 12/02/2022] Open
Abstract
Macropinocytosis refers to the non-specific uptake of extracellular fluid, which plays ubiquitous roles in cell growth, immune surveillance, and virus entry. Despite its widespread occurrence, it remains unclear how its initial cup-shaped plasma membrane extensions form without any external solid support, as opposed to the process of particle uptake during phagocytosis. Here, by developing a computational framework that describes the coupling between the bistable reaction-diffusion processes of active signaling patches and membrane deformation, we demonstrated that the protrusive force localized to the edge of the patches can give rise to a self-enclosing cup structure, without further assumptions of local bending or contraction. Efficient uptake requires a balance among the patch size, magnitude of protrusive force, and cortical tension. Furthermore, our model exhibits cyclic cup formation, coexistence of multiple cups, and cup-splitting, indicating that these complex morphologies self-organize via a common mutually-dependent process of reaction-diffusion and membrane deformation.
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Affiliation(s)
- Nen Saito
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi 444-8787, Japan
| | - Satoshi Sawai
- Department of Basic Science, University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
- Research Center for Complex Systems Biology, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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36
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Kadzik RS, Homa KE, Kovar DR. F-Actin Cytoskeleton Network Self-Organization Through Competition and Cooperation. Annu Rev Cell Dev Biol 2021; 36:35-60. [PMID: 33021819 DOI: 10.1146/annurev-cellbio-032320-094706] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many fundamental cellular processes such as division, polarization, endocytosis, and motility require the assembly, maintenance, and disassembly of filamentous actin (F-actin) networks at specific locations and times within the cell. The particular function of each network is governed by F-actin organization, size, and density as well as by its dynamics. The distinct characteristics of different F-actin networks are determined through the coordinated actions of specific sets of actin-binding proteins (ABPs). Furthermore, a cell typically assembles and uses multiple F-actin networks simultaneously within a common cytoplasm, so these networks must self-organize from a common pool of shared globular actin (G-actin) monomers and overlapping sets of ABPs. Recent advances in multicolor imaging and analysis of ABPs and their associated F-actin networks in cells, as well as the development of sophisticated in vitro reconstitutions of networks with ensembles of ABPs, have allowed the field to start uncovering the underlying principles by which cells self-organize diverse F-actin networks to execute basic cellular functions.
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Affiliation(s)
- Rachel S Kadzik
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA; , .,Department of Molecular BioSciences, Northwestern University, Evanston, Illinois 60208, USA;
| | - Kaitlin E Homa
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA; ,
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA; , .,Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, USA
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37
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Deretic N, Bolger-Munro M, Choi K, Abraham L, Gold MR. The Actin-Disassembly Protein Glia Maturation Factor γ Enhances Actin Remodeling and B Cell Antigen Receptor Signaling at the Immune Synapse. Front Cell Dev Biol 2021; 9:647063. [PMID: 34336818 PMCID: PMC8318000 DOI: 10.3389/fcell.2021.647063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
Signaling by the B cell antigen receptor (BCR) initiates actin remodeling. The assembly of branched actin networks that are nucleated by the Arp2/3 complex exert outward force on the plasma membrane, allowing B cells to form membrane protrusions that can scan the surface of antigen-presenting cells (APCs). The resulting Arp2/3 complex-dependent actin retrograde flow promotes the centripetal movement and progressive coalescence of BCR microclusters, which amplifies BCR signaling. Glia maturation factor γ (GMFγ) is an actin disassembly-protein that releases Arp2/3 complex-nucleated actin filaments from actin networks. By doing so, GMFγ could either oppose the actions of the Arp2/3 complex or support Arp2/3 complex-nucleated actin polymerization by contributing to the recycling of actin monomers and Arp2/3 complexes. We now show that reducing the levels of GMFγ in human B cell lines via transfection with a specific siRNA impairs the ability of B cells to spread on antigen-coated surfaces, decreases the velocity of actin retrograde flow, diminishes the coalescence of BCR microclusters into a central cluster at the B cell-APC contact site, and decreases APC-induced BCR signaling. These effects of depleting GMFγ are similar to what occurs when the Arp2/3 complex is inhibited. This suggests that GMFγ cooperates with the Arp2/3 complex to support BCR-induced actin remodeling and amplify BCR signaling at the immune synapse.
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Affiliation(s)
- Nikola Deretic
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Madison Bolger-Munro
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Kate Choi
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Libin Abraham
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Michael R Gold
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
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38
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Dupré L, Boztug K, Pfajfer L. Actin Dynamics at the T Cell Synapse as Revealed by Immune-Related Actinopathies. Front Cell Dev Biol 2021; 9:665519. [PMID: 34249918 PMCID: PMC8266300 DOI: 10.3389/fcell.2021.665519] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/06/2021] [Indexed: 01/21/2023] Open
Abstract
The actin cytoskeleton is composed of dynamic filament networks that build adaptable local architectures to sustain nearly all cellular activities in response to a myriad of stimuli. Although the function of numerous players that tune actin remodeling is known, the coordinated molecular orchestration of the actin cytoskeleton to guide cellular decisions is still ill defined. T lymphocytes provide a prototypical example of how a complex program of actin cytoskeleton remodeling sustains the spatio-temporal control of key cellular activities, namely antigen scanning and sensing, as well as polarized delivery of effector molecules, via the immunological synapse. We here review the unique knowledge on actin dynamics at the T lymphocyte synapse gained through the study of primary immunodeficiences caused by mutations in genes encoding actin regulatory proteins. Beyond the specific roles of individual actin remodelers, we further develop the view that these operate in a coordinated manner and are an integral part of multiple signaling pathways in T lymphocytes.
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Affiliation(s)
- Loïc Dupré
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases (LBI-RUD), Vienna, Austria.,Department of Dermatology, Medical University of Vienna, Vienna, Austria.,Toulouse Institute for Infectious and Inflammatory Diseases (INFINITy), INSERM, CNRS, Toulouse III Paul Sabatier University, Toulouse, France
| | - Kaan Boztug
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases (LBI-RUD), Vienna, Austria.,St. Anna Children's Cancer Research Institute (CCRI), Vienna, Austria.,CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.,Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.,St. Anna Children's Hospital, Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Laurène Pfajfer
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases (LBI-RUD), Vienna, Austria.,Department of Dermatology, Medical University of Vienna, Vienna, Austria.,Toulouse Institute for Infectious and Inflammatory Diseases (INFINITy), INSERM, CNRS, Toulouse III Paul Sabatier University, Toulouse, France.,St. Anna Children's Cancer Research Institute (CCRI), Vienna, Austria
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39
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Gübeli RJ, Bertoldo D, Shimada K, Gerhold CB, Hurst V, Takahashi Y, Harada K, Mothukuri GK, Wilbs J, Harata M, Gasser SM, Heinis C. In Vitro-Evolved Peptides Bind Monomeric Actin and Mimic Actin-Binding Protein Thymosin-β4. ACS Chem Biol 2021; 16:820-828. [PMID: 33843189 DOI: 10.1021/acschembio.0c00825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Actin is the most abundant protein in eukaryotic cells and is key to many cellular functions. The filamentous form of actin (F-actin) can be studied with help of natural products that specifically recognize it, as for example fluorophore-labeled probes of the bicyclic peptide phalloidin, but no synthetic probes exist for the monomeric form of actin (G-actin). Herein, we have panned a phage display library consisting of more than 10 billion bicyclic peptides against G-actin and isolated binders with low nanomolar affinity and greater than 1000-fold selectivity over F-actin. Sequence analysis revealed a strong similarity to a region of thymosin-β4, a protein that weakly binds G-actin, and competition binding experiments confirmed a common binding region at the cleft between actin subdomains 1 and 3. Together with F-actin-specific peptides that we also isolated, we evaluated the G-actin peptides as probes in pull-down, imaging, and competition binding experiments. While the F-actin peptides were applied successfully for capturing actin in cell lysates and for imaging, the G-actin peptides did not bind in the cellular context, most likely due to competition with thymosin-β4 or related endogenous proteins for the same binding site.
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Affiliation(s)
- Raphael J. Gübeli
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Davide Bertoldo
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Kenji Shimada
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Christian B. Gerhold
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Verena Hurst
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- Faculty of Natural Sciences, University of Basel, 4056 Basel, Switzerland
| | - Yuichiro Takahashi
- Laboratory of Molecular Biology, Tohoku University, Tsutsumidori-Amamiyamachi 1-1, Aoba-ku, Sendai 981-8555, Japan
| | - Kai Harada
- Laboratory of Molecular Biology, Tohoku University, Tsutsumidori-Amamiyamachi 1-1, Aoba-ku, Sendai 981-8555, Japan
| | - Ganesh K. Mothukuri
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Jonas Wilbs
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Masahiko Harata
- Laboratory of Molecular Biology, Tohoku University, Tsutsumidori-Amamiyamachi 1-1, Aoba-ku, Sendai 981-8555, Japan
| | - Susan M. Gasser
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- Faculty of Natural Sciences, University of Basel, 4056 Basel, Switzerland
| | - Christian Heinis
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Actin/microtubule crosstalk during platelet biogenesis in mice is critically regulated by Twinfilin1 and Cofilin1. Blood Adv 2021; 4:2124-2134. [PMID: 32407474 DOI: 10.1182/bloodadvances.2019001303] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/13/2020] [Indexed: 01/24/2023] Open
Abstract
Rearrangements of the microtubule (MT) and actin cytoskeleton are pivotal for platelet biogenesis. Hence, defects in actin- or MT-regulatory proteins are associated with platelet disorders in humans and mice. Previous studies in mice revealed that loss of the actin-depolymerizing factor homology (ADF-H) protein Cofilin1 (Cof1) in megakaryocytes (MKs) results in a moderate macrothrombocytopenia but normal MK numbers, whereas deficiency in another ADF-H protein, Twinfilin1 (Twf1), does not affect platelet production or function. However, recent studies in yeast have indicated a critical synergism between Twf1 and Cof1 in the regulation of actin dynamics. We therefore investigated platelet biogenesis and function in mice lacking both Twf1 and Cof1 in the MK lineage. In contrast to single deficiency in either protein, Twf1/Cof1 double deficiency (DKO) resulted in a severe macrothrombocytopenia and dramatically increased MK numbers in bone marrow and spleen. DKO MKs exhibited defective proplatelet formation in vitro and in vivo as well as impaired spreading and altered assembly of podosome-like structures on collagen and fibrinogen in vitro. These defects were associated with aberrant F-actin accumulation and, remarkably, the formation of hyperstable MT, which appears to be caused by dysregulation of the actin- and MT-binding proteins mDia1 and adenomatous polyposis coli. Surprisingly, the mild functional defects described for Cof1-deficient platelets were only slightly aggravated in DKO platelets suggesting that both proteins are largely dispensable for platelet function in the peripheral blood. In summary, these findings reveal critical redundant functions of Cof1 and Twf1 in ensuring balanced actin/microtubule crosstalk during thrombopoiesis in mice and possibly humans.
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Abstract
In this report, we describe how endothelial cells, the cells lining the interior of blood vessels, invade into tissues to form new vessels through sprouting angiogenesis. We found that endothelial cells use a specific lamellipodia-related membrane protrusion for invasion, which we termed dactylopodia. These protrusions have a special morphology, originate from filopodia, are linked to membrane-ruffling activity, and are specialized in invading into avascular extracellular matrix. Our work lays the foundations for drug discovery targeting sprouting angiogenesis. Sprouting angiogenesis is fundamental for development and contributes to cancer, diabetic retinopathy, and cardiovascular diseases. Sprouting angiogenesis depends on the invasive properties of endothelial tip cells. However, there is very limited knowledge on how tip cells invade into tissues. Here, we show that endothelial tip cells use dactylopodia as the main cellular protrusion for invasion into nonvascular extracellular matrix. We show that dactylopodia and filopodia protrusions are balanced by myosin IIA (NMIIA) and actin-related protein 2/3 (Arp2/3) activity. Endothelial cell-autonomous ablation of NMIIA promotes excessive dactylopodia formation in detriment of filopodia. Conversely, endothelial cell-autonomous ablation of Arp2/3 prevents dactylopodia development and leads to excessive filopodia formation. We further show that NMIIA inhibits Rac1-dependent activation of Arp2/3 by regulating the maturation state of focal adhesions. Our discoveries establish a comprehensive model of how endothelial tip cells regulate its protrusive activity and will pave the way toward strategies to block invasive tip cells during sprouting angiogenesis.
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Bolger-Munro M, Choi K, Cheung F, Liu YT, Dang-Lawson M, Deretic N, Keane C, Gold MR. The Wdr1-LIMK-Cofilin Axis Controls B Cell Antigen Receptor-Induced Actin Remodeling and Signaling at the Immune Synapse. Front Cell Dev Biol 2021; 9:649433. [PMID: 33928084 PMCID: PMC8076898 DOI: 10.3389/fcell.2021.649433] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 03/12/2021] [Indexed: 12/27/2022] Open
Abstract
When B cells encounter membrane-bound antigens, the formation and coalescence of B cell antigen receptor (BCR) microclusters amplifies BCR signaling. The ability of B cells to probe the surface of antigen-presenting cells (APCs) and respond to APC-bound antigens requires remodeling of the actin cytoskeleton. Initial BCR signaling stimulates actin-related protein (Arp) 2/3 complex-dependent actin polymerization, which drives B cell spreading as well as the centripetal movement and coalescence of BCR microclusters at the B cell-APC synapse. Sustained actin polymerization depends on concomitant actin filament depolymerization, which enables the recycling of actin monomers and Arp2/3 complexes. Cofilin-mediated severing of actin filaments is a rate-limiting step in the morphological changes that occur during immune synapse formation. Hence, regulators of cofilin activity such as WD repeat-containing protein 1 (Wdr1), LIM domain kinase (LIMK), and coactosin-like 1 (Cotl1) may also be essential for actin-dependent processes in B cells. Wdr1 enhances cofilin-mediated actin disassembly. Conversely, Cotl1 competes with cofilin for binding to actin and LIMK phosphorylates cofilin and prevents it from binding to actin filaments. We now show that Wdr1 and LIMK have distinct roles in BCR-induced assembly of the peripheral actin structures that drive B cell spreading, and that cofilin, Wdr1, and LIMK all contribute to the actin-dependent amplification of BCR signaling at the immune synapse. Depleting Cotl1 had no effect on these processes. Thus, the Wdr1-LIMK-cofilin axis is critical for BCR-induced actin remodeling and for B cell responses to APC-bound antigens.
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Affiliation(s)
- Madison Bolger-Munro
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Kate Choi
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Faith Cheung
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Yi Tian Liu
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - May Dang-Lawson
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Nikola Deretic
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Connor Keane
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Michael R Gold
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
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Karlsson R, Dráber P. Profilin-A master coordinator of actin and microtubule organization in mammalian cells. J Cell Physiol 2021; 236:7256-7265. [PMID: 33821475 DOI: 10.1002/jcp.30379] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/08/2021] [Accepted: 03/12/2021] [Indexed: 12/17/2022]
Abstract
The last two decades have witnessed a tremendous increase in cell biology data. Not least is this true for studies of the dynamic organization of the microfilament and microtubule systems in animal cells where analyses of the molecular components and their interaction patterns have deepened our understanding of these complex force-generating machineries. Previous observations of a molecular cross-talk between the two systems have now led to the realization of the existence of several intricate mechanisms operating to maintain their coordinated cellular organization. In this short review, we relate to this development by discussing new results concerning the function of the actin regulator profilin 1 as a control component of microfilament-microtubule cross-talk.
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Affiliation(s)
- Roger Karlsson
- Department of Molecular Biosciences, WGI, Stockholm University, Stockholm, Sweden
| | - Pavel Dráber
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
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Malek N, Michrowska A, Mazurkiewicz E, Mrówczyńska E, Mackiewicz P, Mazur AJ. The origin of the expressed retrotransposed gene ACTBL2 and its influence on human melanoma cells' motility and focal adhesion formation. Sci Rep 2021; 11:3329. [PMID: 33558623 PMCID: PMC7870945 DOI: 10.1038/s41598-021-82074-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/08/2021] [Indexed: 01/30/2023] Open
Abstract
We have recently found that β-actin-like protein 2 (actbl2) forms complexes with gelsolin in human melanoma cells and can polymerize. Phylogenetic and bioinformatic analyses showed that actbl2 has a common origin with two non-muscle actins, which share a separate history from the muscle actins. The actin groups' divergence started at the beginning of vertebrate evolution, and actbl2 actins are characterized by the largest number of non-conserved amino acid substitutions of all actins. We also discovered that ACTBL2 is expressed at a very low level in several melanoma cell lines, but a small subset of cells exhibited a high ACTBL2 expression. We found that clones with knocked-out ACTBL2 (CR-ACTBL2) or overexpressing actbl2 (OE-ACTBL2) differ from control cells in the invasion, focal adhesion formation, and actin polymerization ratio, as well as in the formation of lamellipodia and stress fibers. Thus, we postulate that actbl2 is the seventh actin isoform and is essential for cell motility.
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Affiliation(s)
- Natalia Malek
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, ul. Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Aleksandra Michrowska
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, ul. Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Ewa Mazurkiewicz
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, ul. Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Ewa Mrówczyńska
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, ul. Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Paweł Mackiewicz
- Department of Bioinformatics and Genomics, Faculty of Biotechnology, University of Wroclaw, ul. Joliot-Curie 14a, Wroclaw, 50-383, Poland
| | - Antonina J Mazur
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, ul. Joliot-Curie 14a, 50-383, Wroclaw, Poland.
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Shekhar S, Hoeprich GJ, Gelles J, Goode BL. Twinfilin bypasses assembly conditions and actin filament aging to drive barbed end depolymerization. J Cell Biol 2021; 220:e202006022. [PMID: 33226418 PMCID: PMC7686915 DOI: 10.1083/jcb.202006022] [Citation(s) in RCA: 23] [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: 06/03/2020] [Revised: 10/06/2020] [Accepted: 10/29/2020] [Indexed: 01/15/2023] Open
Abstract
Cellular actin networks grow by ATP-actin addition at filament barbed ends and have long been presumed to depolymerize at their pointed ends, primarily after filaments undergo "aging" (ATP hydrolysis and Pi release). The cytosol contains high levels of actin monomers, which favors assembly over disassembly, and barbed ends are enriched in ADP-Pi actin. For these reasons, the potential for a barbed end depolymerization mechanism in cells has received little attention. Here, using microfluidics-assisted TIRF microscopy, we show that mouse twinfilin, a member of the ADF-homology family, induces depolymerization of ADP-Pi barbed ends even under assembly-promoting conditions. Indeed, we observe in single reactions containing micromolar concentrations of actin monomers the simultaneous rapid elongation of formin-bound barbed ends and twinfilin-induced depolymerization of free barbed ends. The data show that twinfilin catalyzes dissociation of subunits from ADP-Pi barbed ends and thereby bypasses filament aging prerequisites to disassemble newly polymerized actin filaments.
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Affiliation(s)
- Shashank Shekhar
- Department of Biology, Brandeis University, Waltham, MA
- Department of Biochemistry, Brandeis University, Waltham, MA
| | | | - Jeff Gelles
- Department of Biochemistry, Brandeis University, Waltham, MA
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Leite SC, Pinto-Costa R, Sousa MM. Actin dynamics in the growth cone: a key player in axon regeneration. Curr Opin Neurobiol 2020; 69:11-18. [PMID: 33359956 DOI: 10.1016/j.conb.2020.11.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 01/01/2023]
Abstract
Neuronal development, maintenance and function depends on the tight regulation of cytoskeleton organization and dynamics. Following injury, adult central nervous system neurons have a limited ability to regenerate and to recapitulate their robust developmental axon growth. This decreased regenerative capacity is set by their inability to establish regeneration-competent growth cones. Growth cones are actin-enriched structures that regulate axon extension rate and direction. During neuronal development, increasing actin dynamics in the growth cone through the regulation of the activity of specific actin-binding proteins leads to increased axon elongation. Here, we will focus on recent findings showing that enhanced axon regeneration in the adult nervous system can be achieved by promoting actin dynamics, or by decreasing actomyosin contraction in the growth cone. These discoveries underscore the importance of actin organization in the growth cone as a key factor to promote axon (re)growth that should be further explored in the future.
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Affiliation(s)
- Sérgio Carvalho Leite
- Institute of Psychiatry and Neurosciences of Paris, INSERM U1266, Université de Paris, 75014 Paris, France
| | - Rita Pinto-Costa
- Nerve Regeneration Group, i3S- Instituto de Investigação e Inovação em Saúde and IBMC- Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal
| | - Monica Mendes Sousa
- Nerve Regeneration Group, i3S- Instituto de Investigação e Inovação em Saúde and IBMC- Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
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Vemula V, Huber T, Ušaj M, Bugyi B, Månsson A. Myosin and gelsolin cooperate in actin filament severing and actomyosin motor activity. J Biol Chem 2020; 296:100181. [PMID: 33303625 PMCID: PMC7948409 DOI: 10.1074/jbc.ra120.015863] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/05/2020] [Accepted: 12/10/2020] [Indexed: 01/06/2023] Open
Abstract
Actin is a major intracellular protein with key functions in cellular motility, signaling, and structural rearrangements. Its dynamic behavior, such as polymerization and depolymerization of actin filaments in response to intracellular and extracellular cues, is regulated by an abundance of actin binding proteins. Out of these, gelsolin is one of the most potent for filament severing. However, myosin motor activity also fragments actin filaments through motor-induced forces, suggesting that these two proteins could cooperate to regulate filament dynamics and motility. To test this idea, we used an in vitro motility assay, where actin filaments are propelled by surface-adsorbed heavy meromyosin (HMM) motor fragments. This allows studies of both motility and filament dynamics using isolated proteins. Gelsolin, at both nanomolar and micromolar Ca2+ concentration, appreciably enhanced actin filament severing caused by HMM-induced forces at 1 mM MgATP, an effect that was increased at higher HMM motor density. This finding is consistent with cooperativity between actin filament severing by myosin-induced forces and by gelsolin. We also observed reduced sliding velocity of the HMM-propelled filaments in the presence of gelsolin, providing further support of myosin-gelsolin cooperativity. Total internal reflection fluorescence microscopy–based single molecule studies corroborated that the velocity reduction was a direct effect of gelsolin binding to the filament and revealed different filament severing pattern of stationary and HMM propelled filaments. Overall, the results corroborate cooperative effects between gelsolin-induced alterations in the actin filaments and changes due to myosin motor activity leading to enhanced F-actin severing of possible physiological relevance.
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Affiliation(s)
- Venukumar Vemula
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Tamás Huber
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Marko Ušaj
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Beáta Bugyi
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary.
| | - Alf Månsson
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden.
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48
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Tian F, Wang X, Ni H, Feng X, Yuan X, Huang Q. The ginsenoside metabolite compound K stimulates glucagon-like peptide-1 secretion in NCI-H716 cells by regulating the RhoA/ROCKs/YAP signaling pathway and cytoskeleton formation. J Pharmacol Sci 2020; 145:88-96. [PMID: 33357784 DOI: 10.1016/j.jphs.2020.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 10/30/2020] [Accepted: 11/09/2020] [Indexed: 02/08/2023] Open
Abstract
Ginsenoside Rb1 has been shown to have antidiabetic and anti-inflammatory effects. Its major metabolite, compound K (CK), can stimulate the secretion of glucagon-like peptide-1 (GLP1), a gastrointestinal hormone that plays a vital role in regulating glucose metabolism. However, the mechanism underlying the regulation of GLP1 secretion by compound K has not been fully explored. This study was designed to investigate whether CK ameliorates incretin impairment by regulating the RhoA/ROCKs/YAP signaling pathway and cytoskeleton formation in NCI-H716 cells. Using NCI-H716 cells as a model cell line for GLP1 secretion, we analyzed the effect of CK on the expression of RhoA/ROCK/YAP pathway components. Our results suggest that the effect of CK on GLP1 secretion depends on the anti-inflammatory effect of CK. We also demonstrated that CK can affect the RhoA/ROCK/YAP pathway, which is downstream of transforming growth factor β1 (TGFβ1), by maintaining the capacity of intestinal differentiation. In addition, this effect was mediated by regulating F/G-actin dynamics. These results provide not only the mechanistic insight for the effect of CK on intestinal L cells but also the molecular basis for the further development of CK as a potential therapeutic agent to treat type 2 diabetes mellitus (T2D).
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Affiliation(s)
- Fengyuan Tian
- Department of Endocrinology, The First Affiliated Hospital of Zhejiang Chinese Medicine University, Hangzhou, 310006, PR China.
| | - Xi Wang
- Central Laboratory, The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, 310006, PR China.
| | - Haixiang Ni
- Department of Endocrinology, The First Affiliated Hospital of Zhejiang Chinese Medicine University, Hangzhou, 310006, PR China.
| | - Xiaohong Feng
- Department of Endocrinology, The First Affiliated Hospital of Zhejiang Chinese Medicine University, Hangzhou, 310006, PR China.
| | - Xiao Yuan
- Department of Endocrinology, The First Affiliated Hospital of Zhejiang Chinese Medicine University, Hangzhou, 310006, PR China.
| | - Qi Huang
- Department of Endocrinology, The First Affiliated Hospital of Zhejiang Chinese Medicine University, Hangzhou, 310006, PR China.
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Fan T, Qu R, Jiang X, Yang Y, Sun B, Huang X, Zhou Z, Ouyang J, Zhong S, Dai J. Spatial organization and crosstalk of vimentin and actin stress fibers regulate the osteogenic differentiation of human adipose-derived stem cells. FASEB J 2020; 35:e21175. [PMID: 33205555 DOI: 10.1096/fj.202000378rr] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 10/10/2020] [Accepted: 10/26/2020] [Indexed: 12/12/2022]
Abstract
Human adipose-derived stem cells (hASCs) are ideal seed cells for tissue engineering due to their multidirectional differentiation potential. Microfilaments, microtubules, and intermediate filaments are responsible for supporting the intracellular space. Vimentin, a type III intermediate filament protein that is specifically expressed in cells of mesenchymal origin, can function as a scaffold and endow cells with tension and shear stress resistance. Actin stress fibers (ASF) act as an important physical device in stress signal transduction, providing stiffness for cells, and promoting osteogenesis. Through direct physical contact, cross-linkers, and spatial interactions, vimentin and actin networks exist as intersecting entities. Spatial interactions occur in the overlapping area of cytoskeleton subsystems, which could affect cell morphology, cell mechanics, and cell fate. However, how does the spatial organization between the cytoskeletal subsystems changed during osteogenesis, especially between vimentin and ASF, is still not understood, and its mechanism effect on cell fate remains unclear. In our study, WB experiment was used to detect the expression changes in Vimentin, ASF, and other proteins. Cells were reconstructed by three-dimensional scanning with fluorescence microscope, and the spatial thickness of vimentin and ASF cytoskeletons and the thickness of the overlapping area between them were calculated, respectively, so as to observe the spatial reorganization of vimentin and ASF in cells. Cytochalasin D (an inhibitor of actin polymerization) and vimentin upregulated/downregulated cells were used to verify the change in the spatial organization between vimentin and ASF and its influence on osteogenesis. Then, heat shock protein 27 (HSP27) was downregulated to illuminate the regulatory mechanisms of spatial organization between vimentin and ASF during osteogenesis. The amounts and the spatial positions of vimentin and actin stress fiber exhibited opposite trends during osteogenesis. Through controlling the anchor sites on the nucleus, intermediate filaments vimentin can reduce the spatial proportion of actin stress fibers, which can be regulated by HSP27. In addition, depolymerization of actin stress fibers lead to lower osteogenic differentiation ability, resulting in osteogenesis and lipogenesis existed simultaneously, that can be resisted by vimentin. Our data indicate that the spatial reorganization of vimentin and actin stress fibers is a key factor in the regulation of the differentiation state of hASCs. And their spatial overlapping area is detrimental to hASCs osteogenesis, providing a new perspective for further exploring the mechanism underlying hASCs osteogenesis.
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Affiliation(s)
- Tingyu Fan
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Rongmei Qu
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Xin Jiang
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Yuchao Yang
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China.,Central Laboratory, Southern Medical University, Guangzhou, China
| | - Bing Sun
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China.,Central Laboratory, Southern Medical University, Guangzhou, China
| | - Xiaolan Huang
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China.,Central Laboratory, Southern Medical University, Guangzhou, China
| | - Zhitao Zhou
- Central Laboratory, Southern Medical University, Guangzhou, China
| | - Jun Ouyang
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Shizhen Zhong
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Jingxing Dai
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
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50
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Nejedlá M, Klebanovych A, Sulimenko V, Sulimenko T, Dráberová E, Dráber P, Karlsson R. The actin regulator profilin 1 is functionally associated with the mammalian centrosome. Life Sci Alliance 2020; 4:4/1/e202000655. [PMID: 33184056 PMCID: PMC7668531 DOI: 10.26508/lsa.202000655] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 12/16/2022] Open
Abstract
The actin regulator profilin 1 recently shown to control microtubule elongation at the cell periphery is found to interact with the γ-tubulin ring complex and tune centrosomal microtubule nucleation. Profilin 1 is a crucial actin regulator, interacting with monomeric actin and several actin-binding proteins controlling actin polymerization. Recently, it has become evident that this profilin isoform associates with microtubules via formins and interferes with microtubule elongation at the cell periphery. Recruitment of microtubule-associated profilin upon extensive actin polymerizations, for example, at the cell edge, enhances microtubule growth, indicating that profilin contributes to the coordination of actin and microtubule organization. Here, we provide further evidence for the profilin-microtubule connection by demonstrating that it also functions in centrosomes where it impacts on microtubule nucleation.
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Affiliation(s)
- Michaela Nejedlá
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Anastasiya Klebanovych
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Vadym Sulimenko
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Tetyana Sulimenko
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Eduarda Dráberová
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Pavel Dráber
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Roger Karlsson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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