1
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Pimm ML, Haarer BK, Nobles AD, Haney LM, Marcin AG, Alcaide Eligio M, Henty-Ridilla JL. Coordination of actin plus-end dynamics by IQGAP1, formin, and capping protein. J Cell Biol 2024; 223:e202305065. [PMID: 38787349 PMCID: PMC11117073 DOI: 10.1083/jcb.202305065] [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: 05/16/2023] [Revised: 04/01/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024] Open
Abstract
Cell processes require precise regulation of actin polymerization that is mediated by plus-end regulatory proteins. Detailed mechanisms that explain plus-end dynamics involve regulators with opposing roles, including factors that enhance assembly, e.g., the formin mDia1, and others that stop growth (capping protein, CP). We explore IQGAP1's roles in regulating actin filament plus-ends and the consequences of perturbing its activity in cells. We confirm that IQGAP1 pauses elongation and interacts with plus ends through two residues (C756 and C781). We directly visualize the dynamic interplay between IQGAP1 and mDia1, revealing that IQGAP1 displaces the formin to influence actin assembly. Using four-color TIRF, we show that IQGAP1's displacement activity extends to formin-CP "decision complexes," promoting end-binding protein turnover at plus-ends. Loss of IQGAP1 or its plus-end activities disrupts morphology and migration, emphasizing its essential role. These results reveal a new role for IQGAP1 in promoting protein turnover on filament ends and provide new insights into how plus-end actin assembly is regulated in cells.
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Affiliation(s)
- Morgan L. Pimm
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Brian K. Haarer
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Alexander D. Nobles
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Laura M. Haney
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Alexandra G. Marcin
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Marcela Alcaide Eligio
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Jessica L. Henty-Ridilla
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA
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2
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Lee ST, Kuboki T, Kidoaki S, Aida Y, Arima Y, Tamada K. A plasmonic metasurface reveals differential motility of breast cancer cell lines at initial phase of adhesion. Colloids Surf B Biointerfaces 2024; 238:113876. [PMID: 38555764 DOI: 10.1016/j.colsurfb.2024.113876] [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: 01/31/2024] [Revised: 03/17/2024] [Accepted: 03/23/2024] [Indexed: 04/02/2024]
Abstract
A plasmonic metasurface composed of a self-assembled monolayer of gold nanoparticles allows for fluorescence imaging with high spatial resolution, owing to the collective excitation of localized surface plasmon resonance. Taking advantage of fluorescence imaging confined to the nano-interface, we examined actin organization in breast cancer cell lines with different metastatic potentials during cell adhesion. Live-cell fluorescence imaging confined within tens of nanometers from the substrate shows a high actin density spanning < 1 μm from the cell edge. Live-cell imaging revealed that the breast cancer cell lines exhibited different actin patterns during the initial phase of cell adhesion (∼ 1 h). Non-tumorous MCF10A cells exhibited symmetric actin localization at the cell edge, whereas highly metastatic MDA-MB-231 cells showed asymmetric actin localization, demonstrating rapid polarization of MDA-MB-231 cells upon adhesion. The rapid actin organization observed by our plasmonic metasurface-based fluorescence imaging provides information on how quickly cancer cells sense the underlying substrate.
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Affiliation(s)
- Shi Ting Lee
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Thasaneeya Kuboki
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Satoru Kidoaki
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yukiko Aida
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yusuke Arima
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
| | - Kaoru Tamada
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
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3
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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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4
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Yang Z, Peng Y, Wang Y, Yang P, Huang Z, Quan T, Xu X, Sun P, Sun Y, Lv J, Wei D, Zhou GQ. KLF5 regulates actin remodeling to enhance the metastasis of nasopharyngeal carcinoma. Oncogene 2024; 43:1779-1795. [PMID: 38649438 DOI: 10.1038/s41388-024-03033-0] [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: 09/26/2023] [Revised: 04/10/2024] [Accepted: 04/11/2024] [Indexed: 04/25/2024]
Abstract
Transcription factors (TFs) engage in various cellular essential processes including differentiation, growth and migration. However, the master TF involved in distant metastasis of nasopharyngeal carcinoma (NPC) remains largely unclear. Here we show that KLF5 regulates actin remodeling to enhance NPC metastasis. We analyzed the msVIPER algorithm-generated transcriptional regulatory networks and identified KLF5 as a master TF of metastatic NPC linked to poor clinical outcomes. KLF5 regulates actin remodeling and lamellipodia formation to promote the metastasis of NPC cells in vitro and in vivo. Mechanistically, KLF5 preferentially occupies distal enhancer regions of ACTN4 to activate its transcription, whereby decoding the informative DNA sequences. ACTN4, extensively localized within actin cytoskeleton, facilitates dense and branched actin networks and lamellipodia formation at the cell leading edge, empowering cells to migrate faster. Collectively, our findings reveal that KLF5 controls robust transcription program of ACTN4 to modulate actin remodeling and augment cell motility which enhances NPC metastasis, and provide new potential biomarkers and therapeutic interventions for NPC.
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Affiliation(s)
- Zhenyu Yang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China
| | - Yanfu Peng
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China
| | - Yaqin Wang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China
| | - Panyang Yang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China
| | - Zhuohui Huang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China
| | - Tingqiu Quan
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China
| | - Xudong Xu
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China
| | - Peng Sun
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Department of Medical Oncology, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China
| | - Ying Sun
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China
| | - Jiawei Lv
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China.
| | - Denghui Wei
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China.
| | - Guan-Qun Zhou
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, 510060, PR China.
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5
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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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6
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Pimm ML, Haarer BK, Nobles AD, Haney LM, Marcin AG, Marcela Alcaide Eligio, Henty-Ridilla JL. Coordination of actin plus-end dynamics by IQGAP1, formin, and capping protein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.04.539490. [PMID: 37205555 PMCID: PMC10187324 DOI: 10.1101/2023.05.04.539490] [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: 05/21/2023]
Abstract
Cell processes require precise regulation of actin polymerization that is mediated by plus-end regulatory proteins. Detailed mechanisms that explain plus-end dynamics involve regulators with opposing roles, including factors that enhance assembly, e.g., the formin mDia1, and others that stop growth (Capping Protein, CPz). We explore IQGAP1's roles regulating actin filament plus-ends and the consequences of perturbing its activity in cells. We confirm that IQGAP1 pauses elongation and interacts with plus ends through two residues (C756 and C781). We directly visualize the dynamic interplay between IQGAP1 and mDia1, revealing that IQGAP1 displaces the formin to influence actin assembly. Using four-color TIRF we show that IQGAP1's displacement activity extends to formin-CPz 'decision complexes', promoting end-binding protein turnover at plus-ends. Loss of IQGAP1 or its plus-end activities disrupts morphology and migration, emphasizing its essential role. These results reveal a new role for IQGAP1 in promoting protein turnover on filament ends and provide new insights into how plus-end actin assembly is regulated in cells.
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Affiliation(s)
- Morgan L Pimm
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Brian K Haarer
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Alexander D Nobles
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Laura M Haney
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Alexandra G Marcin
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Marcela Alcaide Eligio
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Jessica L Henty-Ridilla
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
- Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
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7
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Kumari R, Ven K, Chastney M, Kokate SB, Peränen J, Aaron J, Kogan K, Almeida-Souza L, Kremneva E, Poincloux R, Chew TL, Gunning PW, Ivaska J, Lappalainen P. Focal adhesions contain three specialized actin nanoscale layers. Nat Commun 2024; 15:2547. [PMID: 38514695 PMCID: PMC10957975 DOI: 10.1038/s41467-024-46868-7] [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: 01/25/2024] [Accepted: 03/13/2024] [Indexed: 03/23/2024] Open
Abstract
Focal adhesions (FAs) connect inner workings of cell to the extracellular matrix to control cell adhesion, migration and mechanosensing. Previous studies demonstrated that FAs contain three vertical layers, which connect extracellular matrix to the cytoskeleton. By using super-resolution iPALM microscopy, we identify two additional nanoscale layers within FAs, specified by actin filaments bound to tropomyosin isoforms Tpm1.6 and Tpm3.2. The Tpm1.6-actin filaments, beneath the previously identified α-actinin cross-linked actin filaments, appear critical for adhesion maturation and controlled cell motility, whereas the adjacent Tpm3.2-actin filament layer beneath seems to facilitate adhesion disassembly. Mechanistically, Tpm3.2 stabilizes ACF-7/MACF1 and KANK-family proteins at adhesions, and hence targets microtubule plus-ends to FAs to catalyse their disassembly. Tpm3.2 depletion leads to disorganized microtubule network, abnormally stable FAs, and defects in tail retraction during migration. Thus, FAs are composed of distinct actin filament layers, and each may have specific roles in coupling adhesions to the cytoskeleton, or in controlling adhesion dynamics.
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Affiliation(s)
- Reena Kumari
- HiLIFE Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland
| | - Katharina Ven
- HiLIFE Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland
| | - Megan Chastney
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, FI-20520, Turku, Finland
| | - Shrikant B Kokate
- HiLIFE Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland
| | - Johan Peränen
- HiLIFE Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland
| | - Jesse Aaron
- Advanced Imaging Center, HHMI Janelia Research Campus, Ashburn, VA, 20147, USA
| | - Konstantin Kogan
- HiLIFE Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland
| | - Leonardo Almeida-Souza
- HiLIFE Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Elena Kremneva
- HiLIFE Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland
| | - Renaud Poincloux
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Teng-Leong Chew
- Advanced Imaging Center, HHMI Janelia Research Campus, Ashburn, VA, 20147, USA
| | - Peter W Gunning
- School of Biomedical Sciences, UNSW Sydney, Wallace Wurth Building, Sydney, NSW 2052, Australia
| | - Johanna Ivaska
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, FI-20520, Turku, Finland
- Department of Life Technologies, University of Turku, FI-20520, Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, Turku, Finland
- Foundation for the Finnish Cancer Institute, Tukholmankatu 8, FI-00014, Helsinki, Finland
| | - Pekka Lappalainen
- HiLIFE Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland.
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
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8
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Hummel DR, Hakala M, Toret CP, Kaksonen M. Bsp1, a fungal CPI motif protein, regulates actin filament capping in endocytosis and cytokinesis. Mol Biol Cell 2024; 35:br6. [PMID: 38088874 PMCID: PMC10881157 DOI: 10.1091/mbc.e23-10-0391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/28/2023] [Accepted: 12/07/2023] [Indexed: 01/14/2024] Open
Abstract
The capping of barbed filament ends is a fundamental mechanism for actin regulation. Capping protein controls filament growth and actin turnover in cells by binding to the barbed ends of the filaments with high affinity and slow off-rate. The interaction between capping protein and actin is regulated by capping protein interaction (CPI) motif proteins. We identified a novel CPI motif protein, Bsp1, which is involved in cytokinesis and endocytosis in budding yeast. We demonstrate that Bsp1 is an actin binding protein with a high affinity for capping protein via its CPI motif. In cells, Bsp1 regulates capping protein at endocytic sites and is a major recruiter of capping protein to the cytokinetic actin ring. Lastly, we define Bsp1-related proteins as a distinct fungi-specific CPI protein group. Our results suggest that Bsp1 promotes actin filament capping by the capping protein. This study establishes Bsp1 as a new capping protein regulator and promising candidate to regulate actin networks in fungi.
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Affiliation(s)
- Daniel R. Hummel
- Department of Biochemistry, University of Geneva, 1205 Geneva, Switzerland
| | - Markku Hakala
- Department of Biochemistry, University of Geneva, 1205 Geneva, Switzerland
| | | | - Marko Kaksonen
- Department of Biochemistry, University of Geneva, 1205 Geneva, Switzerland
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9
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Lamb AK, Fernandez AN, Eadaim A, Johnson K, Di Pietro SM. Mechanism of actin capping protein recruitment and turnover during clathrin-mediated endocytosis. J Cell Biol 2024; 223:e202306154. [PMID: 37966720 PMCID: PMC10651396 DOI: 10.1083/jcb.202306154] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/11/2023] [Accepted: 11/01/2023] [Indexed: 11/16/2023] Open
Abstract
Clathrin-mediated endocytosis depends on polymerization of a branched actin network to provide force for membrane invagination. A key regulator in branched actin network formation is actin capping protein (CP), which binds to the barbed end of actin filaments to prevent the addition or loss of actin subunits. CP was thought to stochastically bind actin filaments, but recent evidence shows CP is regulated by a group of proteins containing CP-interacting (CPI) motifs. Importantly, how CPI motif proteins function together to regulate CP is poorly understood. Here, we show Aim21 and Bsp1 work synergistically to recruit CP to the endocytic actin network in budding yeast through their CPI motifs, which also allosterically modulate capping strength. In contrast, twinfilin works downstream of CP recruitment, regulating the turnover of CP through its CPI motif and a non-allosteric mechanism. Collectively, our findings reveal how three CPI motif proteins work together to regulate CP in a stepwise fashion during endocytosis.
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Affiliation(s)
- Andrew K. Lamb
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Andres N. Fernandez
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Abdunaser Eadaim
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Katelyn Johnson
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Santiago M. Di Pietro
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
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10
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Cooper JA. Capping protein regulators of actin assembly in budding yeast. J Cell Biol 2024; 223:e202312031. [PMID: 38085573 PMCID: PMC10716226 DOI: 10.1083/jcb.202312031] [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] [Indexed: 12/18/2023] Open
Abstract
Cellular functions of actin capping protein (CP) regulators are poorly understood. Di Pietro and colleagues (https://doi.org/10.1083/jcb.202306154) shed unprecedented light on this topic using budding yeast. Two proteins with CPI (capping protein interacting) motifs recruit CP to sites of actin assembly, while a third contributes to CP turnover.
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Affiliation(s)
- John A. Cooper
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
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11
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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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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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Fung TS, Chakrabarti R, Higgs HN. The multiple links between actin and mitochondria. Nat Rev Mol Cell Biol 2023; 24:651-667. [PMID: 37277471 PMCID: PMC10528321 DOI: 10.1038/s41580-023-00613-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2023] [Indexed: 06/07/2023]
Abstract
Actin plays many well-known roles in cells, and understanding any specific role is often confounded by the overlap of multiple actin-based structures in space and time. Here, we review our rapidly expanding understanding of actin in mitochondrial biology, where actin plays multiple distinct roles, exemplifying the versatility of actin and its functions in cell biology. One well-studied role of actin in mitochondrial biology is its role in mitochondrial fission, where actin polymerization from the endoplasmic reticulum through the formin INF2 has been shown to stimulate two distinct steps. However, roles for actin during other types of mitochondrial fission, dependent on the Arp2/3 complex, have also been described. In addition, actin performs functions independent of mitochondrial fission. During mitochondrial dysfunction, two distinct phases of Arp2/3 complex-mediated actin polymerization can be triggered. First, within 5 min of dysfunction, rapid actin assembly around mitochondria serves to suppress mitochondrial shape changes and to stimulate glycolysis. At a later time point, at more than 1 h post-dysfunction, a second round of actin polymerization prepares mitochondria for mitophagy. Finally, actin can both stimulate and inhibit mitochondrial motility depending on the context. These motility effects can either be through the polymerization of actin itself or through myosin-based processes, with myosin 19 being an important mitochondrially attached myosin. Overall, distinct actin structures assemble in response to diverse stimuli to affect specific changes to mitochondria.
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Affiliation(s)
- Tak Shun Fung
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA
- Department of Cancer Biology and Genetics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Rajarshi Chakrabarti
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA
- MitoCare Center, Department of Pathology and Genomic Medicine, Thomas Jefferson University, Philadelphia, PA, USA
| | - Henry N Higgs
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA.
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15
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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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16
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Carman PJ, Barrie KR, Rebowski G, Dominguez R. Structures of the free and capped ends of the actin filament. Science 2023; 380:1287-1292. [PMID: 37228182 PMCID: PMC10880383 DOI: 10.1126/science.adg6812] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 05/17/2023] [Indexed: 05/27/2023]
Abstract
The barbed and pointed ends of the actin filament (F-actin) are the sites of growth and shrinkage and the targets of capping proteins that block subunit exchange, including CapZ at the barbed end and tropomodulin at the pointed end. We describe cryo-electron microscopy structures of the free and capped ends of F-actin. Terminal subunits at the free barbed end adopt a "flat" F-actin conformation. CapZ binds with minor changes to the barbed end but with major changes to itself. By contrast, subunits at the free pointed end adopt a "twisted" monomeric actin (G-actin) conformation. Tropomodulin binding forces the second subunit into an F-actin conformation. The structures reveal how the ends differ from the middle in F-actin and how these differences control subunit addition, dissociation, capping, and interactions with end-binding proteins.
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Affiliation(s)
- Peter J. Carman
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
| | - Kyle R. Barrie
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
| | - Grzegorz Rebowski
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
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17
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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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18
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Nguyen MT, Lee W. Induction of miR-665-3p Impairs the Differentiation of Myogenic Progenitor Cells by Regulating the TWF1-YAP1 Axis. Cells 2023; 12:cells12081114. [PMID: 37190023 DOI: 10.3390/cells12081114] [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: 03/10/2023] [Revised: 04/03/2023] [Accepted: 04/06/2023] [Indexed: 05/17/2023] Open
Abstract
Actin dynamics are known to orchestrate various myogenic processes in progenitor cells. Twinfilin-1 (TWF1) is an actin-depolymerizing factor that plays a crucial role in the differentiation of myogenic progenitor cells. However, little is known about the mechanisms underlying the epigenetic regulation of TWF1 expression and impaired myogenic differentiation in the background of muscle wasting. This study investigated how miR-665-3p affects TWF1 expression, actin filaments' modulation, proliferation, and myogenic differentiation in progenitor cells. Palmitic acid, the most prevalent saturated fatty acid (SFA) in food, suppressed TWF1 expression and inhibited the myogenic differentiation of C2C12 cells while increasing the level of miR-665-3p expression. Interestingly, miR-665-3p inhibited TWF1 expression by targeting TWF1 3'UTR directly. In addition, miR-665-3p accumulated filamentous actin (F-actin) and enhanced the nuclear translocation of Yes-associated protein 1 (YAP1), consequently promoting cell cycle progression and proliferation. Furthermore, miR-665-3p suppressed the expressions of myogenic factors, i.e., MyoD, MyoG, and MyHC, and consequently impaired myoblast differentiation. In conclusion, this study suggests that SFA-inducible miR-665-3p suppresses TWF1 expression epigenetically and inhibits myogenic differentiation by facilitating myoblast proliferation via the F-actin/YAP1 axis.
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Affiliation(s)
- Mai Thi Nguyen
- Department of Biochemistry, Dongguk University College of Medicine, 123 Dongdae-ro, Gyeongju 38066, Republic of Korea
| | - Wan Lee
- Department of Biochemistry, Dongguk University College of Medicine, 123 Dongdae-ro, Gyeongju 38066, Republic of Korea
- Channelopathy Research Center, Dongguk University College of Medicine, 32 Dongguk-ro, Ilsan Dong-gu, Goyang 10326, Republic of Korea
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19
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Nguyen MT, Lee W. Mir-302a/TWF1 Axis Impairs the Myogenic Differentiation of Progenitor Cells through F-Actin-Mediated YAP1 Activation. Int J Mol Sci 2023; 24:ijms24076341. [PMID: 37047312 PMCID: PMC10094299 DOI: 10.3390/ijms24076341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 03/17/2023] [Accepted: 03/21/2023] [Indexed: 03/30/2023] Open
Abstract
Actin cytoskeleton dynamics have been found to regulate myogenesis in various progenitor cells, and twinfilin-1 (TWF1), an actin-depolymerizing factor, plays a vital role in actin dynamics and myoblast differentiation. Nevertheless, the molecular mechanisms underlying the epigenetic regulation and biological significance of TWF1 in obesity and muscle wasting have not been explored. Here, we investigated the roles of miR-302a in TWF1 expression, actin filament modulation, proliferation, and myogenic differentiation in C2C12 progenitor cells. Palmitic acid, the most prevalent saturated fatty acid (SFA) in the diet, decreased the expression of TWF1 and impeded myogenic differentiation while increasing the miR-302a levels in C2C12 myoblasts. Interestingly, miR-302a inhibited TWF1 expression directly by targeting its 3′UTR. Furthermore, ectopic expression of miR-302a promoted cell cycle progression and proliferation by increasing the filamentous actin (F-actin) accumulation, which facilitated the nuclear translocation of Yes-associated protein 1 (YAP1). Consequently, by suppressing the expressions of myogenic factors, i.e., MyoD, MyoG, and MyHC, miR-302a impaired myoblast differentiation. Hence, this study demonstrated that SFA-inducible miR-302a suppresses TWF1 expression epigenetically and impairs myogenic differentiation by facilitating myoblast proliferation via F-actin-mediated YAP1 activation.
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Affiliation(s)
- Mai Thi Nguyen
- Department of Biochemistry, Dongguk University College of Medicine, 123 Dongdae-ro, Gyeongju 38066, Republic of Korea
| | - Wan Lee
- Department of Biochemistry, Dongguk University College of Medicine, 123 Dongdae-ro, Gyeongju 38066, Republic of Korea
- Channelopathy Research Center, Dongguk University College of Medicine, 32 Dongguk-ro, Ilsan Dong-gu, Goyang 10326, Republic of Korea
- Correspondence: ; Tel.: +82-54-770-2409
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20
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Ray S, Agarwal P, Nitzan A, Nédélec F, Zaidel-Bar R. Actin-capping protein regulates actomyosin contractility to maintain germline architecture in C. elegans. Development 2023; 150:dev201099. [PMID: 36897576 PMCID: PMC10112912 DOI: 10.1242/dev.201099] [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: 07/12/2022] [Accepted: 02/22/2023] [Indexed: 03/11/2023]
Abstract
Actin dynamics play an important role in tissue morphogenesis, yet the control of actin filament growth takes place at the molecular level. A challenge in the field is to link the molecular function of actin regulators with their physiological function. Here, we report an in vivo role of the actin-capping protein CAP-1 in the Caenorhabditis elegans germline. We show that CAP-1 is associated with actomyosin structures in the cortex and rachis, and its depletion or overexpression led to severe structural defects in the syncytial germline and oocytes. A 60% reduction in the level of CAP-1 caused a twofold increase in F-actin and non-muscle myosin II activity, and laser incision experiments revealed an increase in rachis contractility. Cytosim simulations pointed to increased myosin as the main driver of increased contractility following loss of actin-capping protein. Double depletion of CAP-1 and myosin or Rho kinase demonstrated that the rachis architecture defects associated with CAP-1 depletion require contractility of the rachis actomyosin corset. Thus, we uncovered a physiological role for actin-capping protein in regulating actomyosin contractility to maintain reproductive tissue architecture.
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Affiliation(s)
- Shinjini Ray
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, 6997801 Tel Aviv, Israel
- Graduate Program, Mechanobiology Institute, National University of Singapore,117411, Singapore
| | - Priti Agarwal
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, 6997801 Tel Aviv, Israel
| | - Anat Nitzan
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, 6997801 Tel Aviv, Israel
| | - François Nédélec
- Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1LR, UK
| | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, 6997801 Tel Aviv, Israel
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21
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Rajan S, Kudryashov DS, Reisler E. Actin Bundles Dynamics and Architecture. Biomolecules 2023; 13:450. [PMID: 36979385 PMCID: PMC10046292 DOI: 10.3390/biom13030450] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/04/2023] Open
Abstract
Cells use the actin cytoskeleton for many of their functions, including their division, adhesion, mechanosensing, endo- and phagocytosis, migration, and invasion. Actin bundles are the main constituent of actin-rich structures involved in these processes. An ever-increasing number of proteins that crosslink actin into bundles or regulate their morphology is being identified in cells. With recent advances in high-resolution microscopy and imaging techniques, the complex process of bundles formation and the multiple forms of physiological bundles are beginning to be better understood. Here, we review the physiochemical and biological properties of four families of highly conserved and abundant actin-bundling proteins, namely, α-actinin, fimbrin/plastin, fascin, and espin. We describe the similarities and differences between these proteins, their role in the formation of physiological actin bundles, and their properties-both related and unrelated to their bundling abilities. We also review some aspects of the general mechanism of actin bundles formation, which are known from the available information on the activity of the key actin partners involved in this process.
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Affiliation(s)
- Sudeepa Rajan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Dmitri S. Kudryashov
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
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22
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Wirshing AC, Rodriguez SG, Goode BL. Evolutionary tuning of barbed end competition allows simultaneous construction of architecturally distinct actin structures. J Cell Biol 2023; 222:213854. [PMID: 36729023 PMCID: PMC9929936 DOI: 10.1083/jcb.202209105] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/01/2022] [Accepted: 01/13/2023] [Indexed: 02/03/2023] Open
Abstract
How cells simultaneously assemble actin structures of distinct sizes, shapes, and filamentous architectures is still not well understood. Here, we used budding yeast as a model to investigate how competition for the barbed ends of actin filaments might influence this process. We found that while vertebrate capping protein (CapZ) and formins can simultaneously associate with barbed ends and catalyze each other's displacement, yeast capping protein (Cap1/2) poorly displaces both yeast and vertebrate formins. Consistent with these biochemical differences, in vivo formin-mediated actin cable assembly was strongly attenuated by the overexpression of CapZ but not Cap1/2. Multiwavelength live cell imaging further revealed that actin patches in cap2∆ cells acquire cable-like features over time, including recruitment of formins and tropomyosin. Together, our results suggest that the activities of S. cerevisiae Cap1/2 have been tuned across evolution to allow robust cable assembly by formins in the presence of high cytosolic levels of Cap1/2, which conversely limit patch growth and shield patches from formins.
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Affiliation(s)
- Alison C.E. Wirshing
- https://ror.org/05abbep66Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Sofia Gonzalez Rodriguez
- https://ror.org/05abbep66Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Bruce L. Goode
- https://ror.org/05abbep66Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA,Correspondence to Bruce L. Goode:
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23
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Yang Z, Zhou L, Si T, Chen S, Liu C, Ng KK, Wang Z, Chen Z, Qiu C, Liu G, Wang Q, Zhou X, Zhang L, Yao Z, He S, Yang M, Zhou Z. Lysyl hydroxylase LH1 promotes confined migration and metastasis of cancer cells by stabilizing Septin2 to enhance actin network. Mol Cancer 2023; 22:21. [PMID: 36721170 PMCID: PMC9887875 DOI: 10.1186/s12943-023-01727-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 01/22/2023] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Excessive extracellular matrix deposition and increased stiffness are typical features of solid tumors such as hepatocellular carcinoma (HCC) and pancreatic ductal adenocarcinoma (PDAC). These conditions create confined spaces for tumor cell migration and metastasis. The regulatory mechanism of confined migration remains unclear. METHODS LC-MS was applied to determine the differentially expressed proteins between HCC tissues and corresponding adjacent tissue. Collective migration and single cell migration microfluidic devices with 6 μm-high confined channels were designed and fabricated to mimic the in vivo confined space. 3D invasion assay was created by Matrigel and Collagen I mixture treat to adherent cells. 3D spheroid formation under various stiffness environment was developed by different substitution percentage GelMA. Immunoprecipitation was performed to pull down the LH1-binding proteins, which were identified by LC-MS. Immunofluorescent staining, FRET, RT-PCR, Western blotting, FRAP, CCK-8, transwell cell migration, wound healing, orthotopic liver injection mouse model and in vivo imaging were used to evaluate the target expression and cellular phenotype. RESULTS Lysyl hydroxylase 1 (LH1) promoted the confined migration of cancer cells at both collective and single cell levels. In addition, LH1 enhanced cell invasion in a 3D biomimetic model and spheroid formation in stiffer environments. High LH1 expression correlated with poor prognosis of both HCC and PDAC patients, while it also promoted in vivo metastasis. Mechanistically, LH1 bound and stabilized Septin2 (SEPT2) to enhance actin polymerization, depending on the hydroxylase domain. Finally, the subpopulation with high expression of both LH1 and SEPT2 had the poorest prognosis. CONCLUSIONS LH1 promotes the confined migration and metastasis of cancer cells by stabilizing SEPT2 and thus facilitating actin polymerization.
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Affiliation(s)
- Zihan Yang
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.35030.350000 0004 1792 6846Department of Precision Diagnostic and Therapeutic Technology, City University of Hong Kong Futian Research Institute, Shenzhen, Guangdong China
| | - Li Zhou
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.412461.40000 0004 9334 6536Department of Gastroenterology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Tongxu Si
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.35030.350000 0004 1792 6846Department of Precision Diagnostic and Therapeutic Technology, City University of Hong Kong Futian Research Institute, Shenzhen, Guangdong China
| | - Siyuan Chen
- grid.412461.40000 0004 9334 6536Department of Gastroenterology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Chengxi Liu
- grid.16890.360000 0004 1764 6123State Key Laboratory of Chemical Biology and Drug Discovery, Research Institute for Future Food and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Kelvin Kaki Ng
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.35030.350000 0004 1792 6846Department of Precision Diagnostic and Therapeutic Technology, City University of Hong Kong Futian Research Institute, Shenzhen, Guangdong China
| | - Zesheng Wang
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.35030.350000 0004 1792 6846Department of Precision Diagnostic and Therapeutic Technology, City University of Hong Kong Futian Research Institute, Shenzhen, Guangdong China
| | - Zhiji Chen
- grid.412461.40000 0004 9334 6536Department of Gastroenterology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Chan Qiu
- grid.412461.40000 0004 9334 6536Department of Gastroenterology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Guopan Liu
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.35030.350000 0004 1792 6846Department of Precision Diagnostic and Therapeutic Technology, City University of Hong Kong Futian Research Institute, Shenzhen, Guangdong China
| | - Qingliang Wang
- grid.412461.40000 0004 9334 6536Department of Pathology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xiaoyu Zhou
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.35030.350000 0004 1792 6846Department of Precision Diagnostic and Therapeutic Technology, City University of Hong Kong Futian Research Institute, Shenzhen, Guangdong China
| | - Liang Zhang
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.35030.350000 0004 1792 6846Department of Precision Diagnostic and Therapeutic Technology, City University of Hong Kong Futian Research Institute, Shenzhen, Guangdong China
| | - Zhongping Yao
- grid.16890.360000 0004 1764 6123State Key Laboratory of Chemical Biology and Drug Discovery, Research Institute for Future Food and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Song He
- grid.412461.40000 0004 9334 6536Department of Gastroenterology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Mengsu Yang
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.35030.350000 0004 1792 6846Department of Precision Diagnostic and Therapeutic Technology, City University of Hong Kong Futian Research Institute, Shenzhen, Guangdong China
| | - Zhihang Zhou
- grid.35030.350000 0004 1792 6846Department of Biomedical Sciences, and Tung Biomedical Sciences Center, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, People’s Republic of China ,grid.412461.40000 0004 9334 6536Department of Gastroenterology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
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Fäßler F, Javoor MG, Datler J, Döring H, Hofer FW, Dimchev G, Hodirnau VV, Faix J, Rottner K, Schur FK. ArpC5 isoforms regulate Arp2/3 complex-dependent protrusion through differential Ena/VASP positioning. SCIENCE ADVANCES 2023; 9:eadd6495. [PMID: 36662867 PMCID: PMC9858492 DOI: 10.1126/sciadv.add6495] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 12/20/2022] [Indexed: 05/10/2023]
Abstract
Regulation of the Arp2/3 complex is required for productive nucleation of branched actin networks. An emerging aspect of regulation is the incorporation of subunit isoforms into the Arp2/3 complex. Specifically, both ArpC5 subunit isoforms, ArpC5 and ArpC5L, have been reported to fine-tune nucleation activity and branch junction stability. We have combined reverse genetics and cellular structural biology to describe how ArpC5 and ArpC5L differentially affect cell migration. Both define the structural stability of ArpC1 in branch junctions and, in turn, by determining protrusion characteristics, affect protein dynamics and actin network ultrastructure. ArpC5 isoforms also affect the positioning of members of the Ena/Vasodilator-stimulated phosphoprotein (VASP) family of actin filament elongators, which mediate ArpC5 isoform-specific effects on the actin assembly level. Our results suggest that ArpC5 and Ena/VASP proteins are part of a signaling pathway enhancing cell migration.
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Affiliation(s)
- Florian Fäßler
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | | | - Julia Datler
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Hermann Döring
- Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
- Department of Cell Biology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Florian W. Hofer
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Georgi Dimchev
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | | | - Jan Faix
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Klemens Rottner
- Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
- Department of Cell Biology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Florian K.M. Schur
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
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25
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Lappalainen P, Kotila T, Jégou A, Romet-Lemonne G. Biochemical and mechanical regulation of actin dynamics. Nat Rev Mol Cell Biol 2022; 23:836-852. [PMID: 35918536 DOI: 10.1038/s41580-022-00508-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2022] [Indexed: 12/30/2022]
Abstract
Polymerization of actin filaments against membranes produces force for numerous cellular processes, such as migration, morphogenesis, endocytosis, phagocytosis and organelle dynamics. Consequently, aberrant actin cytoskeleton dynamics are linked to various diseases, including cancer, as well as immunological and neurological disorders. Understanding how actin filaments generate forces in cells, how force production is regulated by the interplay between actin-binding proteins and how the actin-regulatory machinery responds to mechanical load are at the heart of many cellular, developmental and pathological processes. During the past few years, our understanding of the mechanisms controlling actin filament assembly and disassembly has evolved substantially. It has also become evident that the activities of key actin-binding proteins are not regulated solely by biochemical signalling pathways, as mechanical regulation is critical for these proteins. Indeed, the architecture and dynamics of the actin cytoskeleton are directly tuned by mechanical load. Here we discuss the general mechanisms by which key actin regulators, often in synergy with each other, control actin filament assembly, disassembly, and monomer recycling. By using an updated view of actin dynamics as a framework, we discuss how the mechanics and geometry of actin networks control actin-binding proteins, and how this translates into force production in endocytosis and mesenchymal cell migration.
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Affiliation(s)
- Pekka Lappalainen
- Institute of Biotechnology and Helsinki Institute of Life Sciences, University of Helsinki, Helsinki, Finland.
| | - Tommi Kotila
- Institute of Biotechnology and Helsinki Institute of Life Sciences, University of Helsinki, Helsinki, Finland
| | - Antoine Jégou
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
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26
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Myers KR, Fan Y, McConnell P, Cooper JA, Zheng JQ. Actin capping protein regulates postsynaptic spine development through CPI-motif interactions. Front Mol Neurosci 2022; 15:1020949. [PMID: 36245917 PMCID: PMC9557104 DOI: 10.3389/fnmol.2022.1020949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 09/12/2022] [Indexed: 12/02/2022] Open
Abstract
Dendritic spines are small actin-rich protrusions essential for the formation of functional circuits in the mammalian brain. During development, spines begin as dynamic filopodia-like protrusions that are then replaced by relatively stable spines containing an expanded head. Remodeling of the actin cytoskeleton plays a key role in the formation and modification of spine morphology, however many of the underlying regulatory mechanisms remain unclear. Capping protein (CP) is a major actin regulating protein that caps the barbed ends of actin filaments, and promotes the formation of dense branched actin networks. Knockdown of CP impairs the formation of mature spines, leading to an increase in the number of filopodia-like protrusions and defects in synaptic transmission. Here, we show that CP promotes the stabilization of dendritic protrusions, leading to the formation of stable mature spines. However, the localization and function of CP in dendritic spines requires interactions with proteins containing a capping protein interaction (CPI) motif. We found that the CPI motif-containing protein Twinfilin-1 (Twf1) also localizes to spines where it plays a role in CP spine enrichment. The knockdown of Twf1 leads to an increase in the density of filopodia-like protrusions and a decrease in the stability of dendritic protrusions, similar to CP knockdown. Finally, we show that CP directly interacts with Shank and regulates its spine accumulation. These results suggest that spatiotemporal regulation of CP in spines not only controls the actin dynamics underlying the formation of stable postsynaptic spine structures, but also plays an important role in the assembly of the postsynaptic apparatus underlying synaptic function.
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Affiliation(s)
- Kenneth R. Myers
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Yanjie Fan
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Patrick McConnell
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, St. Louis, MO, United States
| | - John A. Cooper
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, St. Louis, MO, United States
| | - James Q. Zheng
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, United States
- Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA, United States
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27
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Structural basis of rapid actin dynamics in the evolutionarily divergent Leishmania parasite. Nat Commun 2022; 13:3442. [PMID: 35705539 PMCID: PMC9200798 DOI: 10.1038/s41467-022-31068-y] [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: 12/03/2021] [Accepted: 06/01/2022] [Indexed: 11/08/2022] Open
Abstract
Actin polymerization generates forces for cellular processes throughout the eukaryotic kingdom, but our understanding of the ‘ancient’ actin turnover machineries is limited. We show that, despite > 1 billion years of evolution, pathogenic Leishmania major parasite and mammalian actins share the same overall fold and co-polymerize with each other. Interestingly, Leishmania harbors a simple actin-regulatory machinery that lacks cofilin ‘cofactors’, which accelerate filament disassembly in higher eukaryotes. By applying single-filament biochemistry we discovered that, compared to mammalian proteins, Leishmania actin filaments depolymerize more rapidly from both ends, and are severed > 100-fold more efficiently by cofilin. Our high-resolution cryo-EM structures of Leishmania ADP-, ADP-Pi- and cofilin-actin filaments identify specific features at actin subunit interfaces and cofilin-actin interactions that explain the unusually rapid dynamics of parasite actin filaments. Our findings reveal how divergent parasites achieve rapid actin dynamics using a remarkably simple set of actin-binding proteins, and elucidate evolution of the actin cytoskeleton. The authors report here the structure-function analysis of highly divergent actin from Leishmania parasite. The study reveals remarkably rapid dynamics of parasite actin as well as the underlying molecular basis, thus providing insight into evolution of the actin cytoskeleton.
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28
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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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29
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Nguyen MT, Won YH, Kwon TW, Lee W. Twinfilin-1 is an essential regulator of myogenic differentiation through the modulation of YAP in C2C12 myoblasts. Biochem Biophys Res Commun 2022; 599:17-23. [DOI: 10.1016/j.bbrc.2022.02.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 12/28/2022]
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30
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Rust MB, Marcello E. Disease association of cyclase-associated protein (CAP): Lessons from gene-targeted mice and human genetic studies. Eur J Cell Biol 2022; 101:151207. [PMID: 35150966 DOI: 10.1016/j.ejcb.2022.151207] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/04/2022] [Accepted: 02/07/2022] [Indexed: 11/03/2022] Open
Abstract
Cyclase-associated protein (CAP) is an actin binding protein that has been initially described as partner of the adenylyl cyclase in yeast. In all vertebrates and some invertebrate species, two orthologs, named CAP1 and CAP2, have been described. CAP1 and CAP2 are characterized by a similar multidomain structure, but different expression patterns. Several molecular studies clarified the biological function of the different CAP domains, and they shed light onto the mechanisms underlying CAP-dependent regulation of actin treadmilling. However, CAPs are crucial elements not only for the regulation of actin dynamics, but also for signal transduction pathways. During recent years, human genetic studies and the analysis of gene-targeted mice provided important novel insights into the physiological roles of CAPs and their involvement in the pathogenesis of several diseases. In the present review, we summarize and discuss recent progress in our understanding of CAPs' physiological functions, focusing on heart, skeletal muscle and central nervous system as well as their involvement in the mechanisms controlling metabolism. Remarkably, loss of CAPs or impairment of CAPs-dependent pathways can contribute to the pathogenesis of different diseases. Overall, these studies unraveled CAPs complexity highlighting their capability to orchestrate structural and signaling pathways in the cells.
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Affiliation(s)
- Marco B Rust
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus-Liebig-University Giessen, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany.
| | - Elena Marcello
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, 20133 Milan, Italy.
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31
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Abstract
The precise assembly and disassembly of actin filaments is required for several cellular processes, and their regulation has been scrutinized for decades. Twenty years ago, a handful of studies marked the advent of a new type of experiment to study actin dynamics: using optical microscopy to look at individual events, taking place on individual filaments in real time. Here, we summarize the main characteristics of this approach and how it has changed our ability to understand actin assembly dynamics. We also highlight some of its caveats and reflect on what we have learned over the past 20 years, leading us to propose a set of guidelines, which we hope will contribute to a better exploitation of this powerful tool.
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32
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Chandra A, Butler MT, Bear JE, Haugh JM. Modeling cell protrusion predicts how myosin II and actin turnover affect adhesion-based signaling. Biophys J 2022; 121:102-118. [PMID: 34861242 PMCID: PMC8758409 DOI: 10.1016/j.bpj.2021.11.2889] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 11/03/2021] [Accepted: 11/29/2021] [Indexed: 01/07/2023] Open
Abstract
Orchestration of cell migration is essential for development, tissue regeneration, and the immune response. This dynamic process integrates adhesion, signaling, and cytoskeletal subprocesses across spatial and temporal scales. In mesenchymal cells, adhesion complexes bound to extracellular matrix mediate both biochemical signal transduction and physical interaction with the F-actin cytoskeleton. Here, we present a mathematical model that offers insight into both aspects, considering spatiotemporal dynamics of nascent adhesions, active signaling molecules, mechanical clutching, actin treadmilling, and nonmuscle myosin II contractility. At the core of the model is a positive feedback loop, whereby adhesion-based signaling promotes generation of barbed ends at, and protrusion of, the cell's leading edge, which in turn promotes formation and stabilization of nascent adhesions. The model predicts a switch-like transition and optimality of membrane protrusion, determined by the balance of actin polymerization and retrograde flow, with respect to extracellular matrix density. The model, together with new experimental measurements, explains how protrusion can be modulated by mechanical effects (nonmuscle myosin II contractility and adhesive bond stiffness) and F-actin turnover.
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Affiliation(s)
- Ankit Chandra
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina
| | - Mitchell T. Butler
- Department of Cell Biology and Physiology, UNC Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - James E. Bear
- Department of Cell Biology and Physiology, UNC Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Jason M. Haugh
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina,Corresponding author
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33
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Bamburg JR, Minamide LS, Wiggan O, Tahtamouni LH, Kuhn TB. Cofilin and Actin Dynamics: Multiple Modes of Regulation and Their Impacts in Neuronal Development and Degeneration. Cells 2021; 10:cells10102726. [PMID: 34685706 PMCID: PMC8534876 DOI: 10.3390/cells10102726] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/06/2021] [Accepted: 10/07/2021] [Indexed: 02/06/2023] Open
Abstract
Proteins of the actin depolymerizing factor (ADF)/cofilin family are ubiquitous among eukaryotes and are essential regulators of actin dynamics and function. Mammalian neurons express cofilin-1 as the major isoform, but ADF and cofilin-2 are also expressed. All isoforms bind preferentially and cooperatively along ADP-subunits in F-actin, affecting the filament helical rotation, and when either alone or when enhanced by other proteins, promotes filament severing and subunit turnover. Although self-regulating cofilin-mediated actin dynamics can drive motility without post-translational regulation, cells utilize many mechanisms to locally control cofilin, including cooperation/competition with other proteins. Newly identified post-translational modifications function with or are independent from the well-established phosphorylation of serine 3 and provide unexplored avenues for isoform specific regulation. Cofilin modulates actin transport and function in the nucleus as well as actin organization associated with mitochondrial fission and mitophagy. Under neuronal stress conditions, cofilin-saturated F-actin fragments can undergo oxidative cross-linking and bundle together to form cofilin-actin rods. Rods form in abundance within neurons around brain ischemic lesions and can be rapidly induced in neurites of most hippocampal and cortical neurons through energy depletion or glutamate-induced excitotoxicity. In ~20% of rodent hippocampal neurons, rods form more slowly in a receptor-mediated process triggered by factors intimately connected to disease-related dementias, e.g., amyloid-β in Alzheimer’s disease. This rod-inducing pathway requires a cellular prion protein, NADPH oxidase, and G-protein coupled receptors, e.g., CXCR4 and CCR5. Here, we will review many aspects of cofilin regulation and its contribution to synaptic loss and pathology of neurodegenerative diseases.
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Affiliation(s)
- James R. Bamburg
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
- Correspondence: ; Tel.: +1-970-988-9120; Fax: +1-970-491-0494
| | - Laurie S. Minamide
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
| | - O’Neil Wiggan
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
| | - Lubna H. Tahtamouni
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
- Department of Biology and Biotechnology, The Hashemite University, Zarqa 13115, Jordan
| | - Thomas B. Kuhn
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
- Department of Chemistry and Biochemistry, University of Alaska, Fairbanks, AK 99775, USA
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34
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Funk J, Merino F, Schaks M, Rottner K, Raunser S, Bieling P. A barbed end interference mechanism reveals how capping protein promotes nucleation in branched actin networks. Nat Commun 2021; 12:5329. [PMID: 34504078 PMCID: PMC8429771 DOI: 10.1038/s41467-021-25682-5] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 08/18/2021] [Indexed: 12/26/2022] Open
Abstract
Heterodimeric capping protein (CP/CapZ) is an essential factor for the assembly of branched actin networks, which push against cellular membranes to drive a large variety of cellular processes. Aside from terminating filament growth, CP potentiates the nucleation of actin filaments by the Arp2/3 complex in branched actin networks through an unclear mechanism. Here, we combine structural biology with in vitro reconstitution to demonstrate that CP not only terminates filament elongation, but indirectly stimulates the activity of Arp2/3 activating nucleation promoting factors (NPFs) by preventing their association to filament barbed ends. Key to this function is one of CP's C-terminal "tentacle" extensions, which sterically masks the main interaction site of the terminal actin protomer. Deletion of the β tentacle only modestly impairs capping. However, in the context of a growing branched actin network, its removal potently inhibits nucleation promoting factors by tethering them to capped filament ends. End tethering of NPFs prevents their loading with actin monomers required for activation of the Arp2/3 complex and thus strongly inhibits branched network assembly both in cells and reconstituted motility assays. Our results mechanistically explain how CP couples two opposed processes-capping and nucleation-in branched actin network assembly.
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Affiliation(s)
- Johanna Funk
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Department of Protein Evolution, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Matthias Schaks
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
| | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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35
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Devitt CC, Lee C, Cox RM, Papoulas O, Alvarado J, Shekhar S, Marcotte EM, Wallingford JB. Twinfilin1 controls lamellipodial protrusive activity and actin turnover during vertebrate gastrulation. J Cell Sci 2021; 134:jcs254011. [PMID: 34060614 PMCID: PMC8325956 DOI: 10.1242/jcs.254011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 05/12/2021] [Indexed: 11/20/2022] Open
Abstract
The dynamic control of the actin cytoskeleton is a key aspect of essentially all animal cell movements. Experiments in single migrating cells and in vitro systems have provided an exceptionally deep understanding of actin dynamics. However, we still know relatively little of how these systems are tuned in cell-type-specific ways, for example in the context of collective cell movements that sculpt the early embryo. Here, we provide an analysis of the actin-severing and depolymerization machinery during vertebrate gastrulation, with a focus on Twinfilin1 (Twf1) in Xenopus. We find that Twf1 is essential for convergent extension, and loss of Twf1 results in a disruption of lamellipodial dynamics and polarity. Moreover, Twf1 loss results in a failure to assemble polarized cytoplasmic actin cables, which are essential for convergent extension. These data provide an in vivo complement to our more-extensive understanding of Twf1 action in vitro and provide new links between the core machinery of actin regulation and the specialized cell behaviors of embryonic morphogenesis.
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Affiliation(s)
- Caitlin C. Devitt
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA
| | - Chanjae Lee
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA
| | - Rachael M. Cox
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA
| | - Ophelia Papoulas
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA
| | - José Alvarado
- Department of Physics, University of Texas, Austin, TX 78712, USA
| | - Shashank Shekhar
- Department of Physics, Emory University, Atlanta, GA 30322, USA
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA
| | - Edward M. Marcotte
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA
| | - John B. Wallingford
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA
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36
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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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Miyoshi T, Belyantseva IA, Kitajiri SI, Miyajima H, Nishio SY, Usami SI, Kim BJ, Choi BY, Omori K, Shroff H, Friedman TB. Human deafness-associated variants alter the dynamics of key molecules in hair cell stereocilia F-actin cores. Hum Genet 2021; 141:363-382. [PMID: 34232383 DOI: 10.1007/s00439-021-02304-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/15/2021] [Indexed: 12/16/2022]
Abstract
Stereocilia protrude up to 100 µm from the apical surface of vertebrate inner ear hair cells and are packed with cross-linked filamentous actin (F-actin). They function as mechanical switches to convert sound vibration into electrochemical neuronal signals transmitted to the brain. Several genes encode molecular components of stereocilia including actin monomers, actin regulatory and bundling proteins, motor proteins and the proteins of the mechanotransduction complex. A stereocilium F-actin core is a dynamic system, which is continuously being remodeled while maintaining an outwardly stable architecture under the regulation of F-actin barbed-end cappers, severing proteins and crosslinkers. The F-actin cores of stereocilia also provide a pathway for motor proteins to transport cargos including components of tip-link densities, scaffolding proteins and actin regulatory proteins. Deficiencies and mutations of stereocilia components that disturb this "dynamic equilibrium" in stereocilia can induce morphological changes and disrupt mechanotransduction causing sensorineural hearing loss, best studied in mouse and zebrafish models. Currently, at least 23 genes, associated with human syndromic and nonsyndromic hearing loss, encode proteins involved in the development and maintenance of stereocilia F-actin cores. However, it is challenging to predict how variants associated with sensorineural hearing loss segregating in families affect protein function. Here, we review the functions of several molecular components of stereocilia F-actin cores and provide new data from our experimental approach to directly evaluate the pathogenicity and functional impact of reported and novel variants of DIAPH1 in autosomal-dominant DFNA1 hearing loss using single-molecule fluorescence microscopy.
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Affiliation(s)
- Takushi Miyoshi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA. .,Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA
| | - Shin-Ichiro Kitajiri
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Hiroki Miyajima
- Department of Otolaryngology, Shinshu University School of Medicine, Matsumoto, 390-8621, Japan.,Department of Otolaryngology, Aizawa Hospital, Matsumoto, 390-8510, Japan
| | - Shin-Ya Nishio
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Shin-Ichi Usami
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Bong Jik Kim
- Department of Otolaryngology-Head and Neck Surgery, Chungnam National University College of Medicine, Chungnam National University Sejong Hospital, Sejong, 30099, South Korea.,Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, South Korea
| | - Byung Yoon Choi
- Department of Otorhinolaryngology, Seoul National University Bundang Hospital, Seongnam, 13620, South Korea
| | - Koichi Omori
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Hari Shroff
- Laboratory of High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA
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38
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Lamb AK, Fernandez AN, Peersen OB, Di Pietro SM. The dynein light chain protein Tda2 functions as a dimerization engine to regulate actin capping protein during endocytosis. Mol Biol Cell 2021; 32:1459-1473. [PMID: 34081539 PMCID: PMC8351736 DOI: 10.1091/mbc.e21-01-0032] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Clathrin- and actin-mediated endocytosis is a fundamental process in eukaryotic cells. Previously, we discovered Tda2 as a new yeast dynein light chain (DLC) that works with Aim21 to regulate actin assembly during endocytosis. Here we show Tda2 functions as a dimerization engine bringing two Aim21 molecules together using a novel binding surface different than the canonical DLC ligand binding groove. Point mutations on either protein that diminish the Tda2-Aim21 interaction in vitro cause the same in vivo phenotype as TDA2 deletion showing reduced actin capping protein (CP) recruitment and increased filamentous actin at endocytic sites. Remarkably, chemically induced dimerization of Aim21 rescues the endocytic phenotype of TDA2 deletion. We also uncovered a CP interacting motif in Aim21, expanding its function to a fundamental cellular pathway and showing such motif exists outside mammalian cells. Furthermore, specific disruption of this motif causes the same deficit of actin CP recruitment and increased filamentous actin at endocytic sites as AIM21 deletion. Thus, the data indicate the Tda2-Aim21 complex functions in actin assembly primarily through CP regulation. Collectively, our results provide a mechanistic view of the Tda2-Aim21 complex and its function in actin network regulation at endocytic sites.
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Affiliation(s)
- Andrew K Lamb
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870
| | - Andres N Fernandez
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870
| | - Olve B Peersen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870
| | - Santiago M Di Pietro
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870
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39
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Abstract
The turnover of actin filament networks in cells has long been considered to reflect the treadmilling behavior of pure actin filaments in vitro, where only the pointed ends depolymerize. Newly discovered molecular mechanisms challenge this notion, as they provide evidence of situations in which growing and depolymerizing barbed ends coexist.
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Affiliation(s)
- Guillaume Romet-Lemonne
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
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40
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Articular Chondrocyte Phenotype Regulation through the Cytoskeleton and the Signaling Processes That Originate from or Converge on the Cytoskeleton: Towards a Novel Understanding of the Intersection between Actin Dynamics and Chondrogenic Function. Int J Mol Sci 2021; 22:ijms22063279. [PMID: 33807043 PMCID: PMC8004672 DOI: 10.3390/ijms22063279] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 02/08/2023] Open
Abstract
Numerous studies have assembled a complex picture, in which extracellular stimuli and intracellular signaling pathways modulate the chondrocyte phenotype. Because many diseases are mechanobiology-related, this review asked to what extent phenotype regulators control chondrocyte function through the cytoskeleton and cytoskeleton-regulating signaling processes. Such information would generate leverage for advanced articular cartilage repair. Serial passaging, pro-inflammatory cytokine signaling (TNF-α, IL-1α, IL-1β, IL-6, and IL-8), growth factors (TGF-α), and osteoarthritis not only induce dedifferentiation but also converge on RhoA/ROCK/Rac1/mDia1/mDia2/Cdc42 to promote actin polymerization/crosslinking for stress fiber (SF) formation. SF formation takes center stage in phenotype control, as both SF formation and SOX9 phosphorylation for COL2 expression are ROCK activity-dependent. Explaining how it is molecularly possible that dedifferentiation induces low COL2 expression but high SF formation, this review theorized that, in chondrocyte SOX9, phosphorylation by ROCK might effectively be sidelined in favor of other SF-promoting ROCK substrates, based on a differential ROCK affinity. In turn, actin depolymerization for redifferentiation would “free-up” ROCK to increase COL2 expression. Moreover, the actin cytoskeleton regulates COL1 expression, modulates COL2/aggrecan fragment generation, and mediates a fibrogenic/catabolic expression profile, highlighting that actin dynamics-regulating processes decisively control the chondrocyte phenotype. This suggests modulating the balance between actin polymerization/depolymerization for therapeutically controlling the chondrocyte phenotype.
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Takeda S, Koike R, Fujiwara I, Narita A, Miyata M, Ota M, Maéda Y. Structural Insights into the Regulation of Actin Capping Protein by Twinfilin C-terminal Tail. J Mol Biol 2021; 433:166891. [PMID: 33639213 DOI: 10.1016/j.jmb.2021.166891] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/17/2021] [Accepted: 02/17/2021] [Indexed: 12/19/2022]
Abstract
Twinfilin is a conserved actin regulator that interacts with actin capping protein (CP) via C terminus residues (TWtail) that exhibits sequence similarity with the CP interaction (CPI) motif of CARMIL. Here we report the crystal structure of TWtail in complex with CP. Our structure showed that although TWtail and CARMIL CPI bind CP to an overlapping surface via their middle regions, they exhibit different CP-binding modes at both termini. Consequently, TWtail and CARMIL CPI restrict the CP in distinct conformations of open and closed forms, respectively. Interestingly, V-1, which targets CP away from the TWtail binding site, also favors the open-form CP. Consistently, TWtail forms a stable ternary complex with CP and V-1, a striking contrast to CARMIL CPI, which rapidly dissociates V-1 from CP. Our results demonstrate that TWtail is a unique CP-binding motif that regulates CP in a manner distinct from CARMIL CPI.
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Affiliation(s)
- Shuichi Takeda
- Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan.
| | - Ryotaro Koike
- Graduate School of Informatics, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Ikuko Fujiwara
- Graduate School of Science, Osaka City University, Osaka, Osaka 558-8585, Japan
| | - Akihiro Narita
- Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Makoto Miyata
- Graduate School of Science, Osaka City University, Osaka, Osaka 558-8585, Japan; The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, Osaka, Osaka 558-8585, Japan
| | - Motonori Ota
- Graduate School of Informatics, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Yuichiro Maéda
- Graduate School of Informatics, Nagoya University, Nagoya, Aichi 464-8601, Japan
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