1
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Courtemanche N, Henty-Ridilla JL. Actin filament dynamics at barbed ends: New structures, new insights. Curr Opin Cell Biol 2024; 90:102419. [PMID: 39178734 PMCID: PMC11492572 DOI: 10.1016/j.ceb.2024.102419] [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: 05/01/2024] [Revised: 06/30/2024] [Accepted: 07/31/2024] [Indexed: 08/26/2024]
Abstract
The dynamic actin cytoskeleton contributes to many critical biological processes by providing the structural support underlying the morphology of most cells, facilitating intracellular transport, and generating forces required for cell motility and division. To execute many of these functions, actin monomers polymerize into polarized filaments that display different structural and biochemical properties at each end. Filament dynamics are regulated by diverse regulatory proteins which collaborate to dictate rates of elongation and disassembly, particularly at the fast-growing barbed (plus) end. This review highlights the biochemical mechanisms of six barbed end regulatory proteins: formin, profilin, capping protein, IQGAP1, cyclase-associated protein, and twinfilin. We discuss how individual proteins influence actin dynamics and how several intriguing complex assemblies influence the polymerization fate of actin filaments. Understanding these mechanisms offers insights into how actin is regulated in essential cell processes and dysregulated in disease.
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Affiliation(s)
- Naomi Courtemanche
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Jessica L Henty-Ridilla
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
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2
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Li XM, Xu K, Wang JY, Guo JY, Wang XH, Zeng L, Wan B, Wang J, Chu BB, Yang GY, Pan JJ, Hao WB. The actin cytoskeleton is important for pseudorabies virus infection. Virology 2024; 600:110233. [PMID: 39255726 DOI: 10.1016/j.virol.2024.110233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 08/06/2024] [Accepted: 09/05/2024] [Indexed: 09/12/2024]
Abstract
Viruses are dependent on the host factors for their replication and survival. Therefore, identification of host factors that druggable for antiviral development is crucial. The actin cytoskeleton plays an important role in the virus infection. The dynamics change of actin and its function are regulated by multiple actin-associated proteins (AAPs). However, the role and mechanism of various AAPs in the life cycle of virus are still enigmatic. In this study, we analyzed the roles of actin and AAPs in the replication of pseudorabies virus (PRV). Using a library of compounds targeting AAPs, our data found that multiple AAPs, such as Rho-GTPases, Rock, Myosin and Formin were involved in PRV infection. Besides, our result demonstrated that the actin-binding protein Drebrin was also participated in PRV infection. Further studies are necessary to elucidate the molecular mechanism of AAPs in the virus life cycle, in the hope of mining host factors for antiviral developments.
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Affiliation(s)
- Xin-Man Li
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China
| | - Kun Xu
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China
| | - Jin-Yuan Wang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China
| | - Jie-Yuan Guo
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China
| | - Xiao-Han Wang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China
| | - Lei Zeng
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China
| | - Bo Wan
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Ministry of Education Key Laboratory for Animal Pathogens and Biosafety, Zhengzhou 450046, China
| | - Jiang Wang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China; Ministry of Education Key Laboratory for Animal Pathogens and Biosafety, Zhengzhou 450046, China
| | - Bei-Bei Chu
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China; Ministry of Education Key Laboratory for Animal Pathogens and Biosafety, Zhengzhou 450046, China
| | - Guo-Yu Yang
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China; Henan University of Animal Husbandry and Economy, Zhengzhou, 450047, China
| | - Jia-Jia Pan
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, 450046, China; Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, 450046, China; Ministry of Education Key Laboratory for Animal Pathogens and Biosafety, Zhengzhou 450046, China.
| | - Wen-Bo Hao
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China.
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3
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Ma Q, Surya W, He D, Yang H, Han X, Nai MH, Lim CT, Torres J, Miao Y. Spa2 remodels ADP-actin via molecular condensation under glucose starvation. Nat Commun 2024; 15:4491. [PMID: 38802374 PMCID: PMC11130202 DOI: 10.1038/s41467-024-48863-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 05/15/2024] [Indexed: 05/29/2024] Open
Abstract
Actin nucleotide-dependent actin remodeling is essential to orchestrate signal transduction and cell adaptation. Rapid energy starvation requires accurate and timely reorganization of the actin network. Despite distinct treadmilling mechanisms of ADP- and ATP-actin filaments, their filament structures are nearly identical. How other actin-binding proteins regulate ADP-actin filament assembly is unclear. Here, we show that Spa2 which is the polarisome scaffold protein specifically remodels ADP-actin upon energy starvation in budding yeast. Spa2 triggers ADP-actin monomer nucleation rapidly through a dimeric core of Spa2 (aa 281-535). Concurrently, the intrinsically disordered region (IDR, aa 1-281) guides Spa2 undergoing phase separation and wetting on the surface of ADP-G-actin-derived F-actin and bundles the filaments. Both ADP-actin-specific nucleation and bundling activities of Spa2 are actin D-loop dependent. The IDR and nucleation core of Spa2 are evolutionarily conserved by coexistence in the fungus kingdom, suggesting a universal adaptation mechanism in the fungal kingdom in response to glucose starvation, regulating ADP-G-actin and ADP-F-actin with high nucleotide homogeneity.
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Affiliation(s)
- Qianqian Ma
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Wahyu Surya
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Danxia He
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Hanmeng Yang
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Xiao Han
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Mui Hoon Nai
- Department of Biomedical Engineering, National University of Singapore, 117583, Singapore, Singapore
| | - Chwee Teck Lim
- Department of Biomedical Engineering, National University of Singapore, 117583, Singapore, Singapore
- Institute for Health Innovation and Technology (iHealthtech), National University of Singapore, 119276, Singapore, Singapore
| | - Jaume Torres
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore.
- Institute for Digital Molecular Analytics and Science, Nanyang Technological University, 636921, Singapore, Singapore.
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4
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Mahin A, Chikmagalur Ravindra S, Ramesh P, Naik P, Raju R, Keshava Prasad TS, Abhinand CS. Unveiling Actin Cytoskeleton Role in Mediating Chikungunya-Associated Arthritis: An Integrative Proteome-Metabolome Study. Vector Borne Zoonotic Dis 2024. [PMID: 38717066 DOI: 10.1089/vbz.2024.0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024] Open
Abstract
Background: Chikungunya is a zoonotic disease caused by the Chikungunya virus (CHIKV), primarily transmitted to humans through infected Aedes mosquitoes. The infection is characterized by symptoms such as high fever, musculoskeletal pain, polyarthritis, and a rash, which can lead to severe complications such as encephalitis, meningitis, and even fatalities. While many disease manifestations resemble those of other viral infections, chronic arthritis caused by CHIKV is unique, and its molecular mechanisms remain ill-defined. Materials and Methods: Proteomics data from both cellular and patient levels of CHIKV infection were curated from PubMed and screened using inclusion and exclusion criteria. Patient serum proteomics data obtained from P RIDE underwent reanalysis using Proteome Discoverer 2.2. Enrichment and protein-protein interaction network analysis were conducted on differentially expressed proteins from both serum and cellular datasets. Metabolite data from CHIKV-infected patients were further retrieved, and their protein binding partners were identified using BindingDB. The protein-metabolite interaction pathway was further developed using MetaboAnalyst. Results: The proteomics data analysis revealed differential expression of proteins involved in critical host mechanisms, such as cholesterol metabolism and mRNA splicing, during CHIKV infection. Consistent upregulation of two actin cytoskeleton proteins, TAGLN2 and PFN1, was noted in both serum and cellular datasets, and their upregulations are associated with arthritis. Furthermore, alterations in purine metabolism were observed in the integrative proteome-metabolome analysis, correlating with cytoskeletal remodelling. Conclusion: Collectively, this integrative view sheds light on the involvement of actin cytoskeleton remodeling proteins and purine metabolic pathways in the development of arthritis during CHIKV infection.
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Affiliation(s)
- Althaf Mahin
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Center, Yenepoya (Deemed to Be University), Mangalore, India
| | - Sourav Chikmagalur Ravindra
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Center, Yenepoya (Deemed to Be University), Mangalore, India
- Department of Biosciences, Mangalore University, Mangalore, India
| | - Poornima Ramesh
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Center, Yenepoya (Deemed to Be University), Mangalore, India
| | - Prashantha Naik
- Department of Biosciences, Mangalore University, Mangalore, India
| | - Rajesh Raju
- Centre for Integrative Omics Data Science (CIODS), Yenepoya (Deemed to Be University), Mangalore, India
| | | | - Chandran S Abhinand
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Center, Yenepoya (Deemed to Be University), Mangalore, India
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5
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Oosterheert W, Boiero Sanders M, Funk J, Prumbaum D, Raunser S, Bieling P. Molecular mechanism of actin filament elongation by formins. Science 2024; 384:eadn9560. [PMID: 38603491 DOI: 10.1126/science.adn9560] [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: 01/09/2024] [Accepted: 03/05/2024] [Indexed: 04/13/2024]
Abstract
Formins control the assembly of actin filaments (F-actin) that drive cell morphogenesis and motility in eukaryotes. However, their molecular interaction with F-actin and their mechanism of action remain unclear. In this work, we present high-resolution cryo-electron microscopy structures of F-actin barbed ends bound by three distinct formins, revealing a common asymmetric formin conformation imposed by the filament. Formation of new intersubunit contacts during actin polymerization sterically displaces formin and triggers its translocation. This "undock-and-lock" mechanism explains how actin-filament growth is coordinated with formin movement. Filament elongation speeds are controlled by the positioning and stability of actin-formin interfaces, which distinguish fast and slow formins. Furthermore, we provide a structure of the actin-formin-profilin ring complex, which resolves how profilin is rapidly released from the barbed end during filament elongation.
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Affiliation(s)
- Wout Oosterheert
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Micaela Boiero Sanders
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Johanna Funk
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Daniel Prumbaum
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
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6
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Ono S. Segregated localization of two calponin-related proteins within sarcomeric thin filaments in Caenorhabditis elegans striated muscle. Cytoskeleton (Hoboken) 2024; 81:127-140. [PMID: 37792405 PMCID: PMC11249056 DOI: 10.1002/cm.21794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 09/14/2023] [Accepted: 09/15/2023] [Indexed: 10/05/2023]
Abstract
The calponin family proteins are expressed in both muscle and non-muscle cells and involved in the regulation of cytoskeletal dynamics and cell contractility. In the nematode Caenorhabditis elegans, UNC-87 and CLIK-1 are calponin-related proteins with 42% identical amino acid sequences containing seven calponin-like motifs. Genetic studies demonstrated that UNC-87 and CLIK-1 have partially redundant function in regulating actin cytoskeletal organization in striated and non-striated muscle cells. However, biochemical studies showed that UNC-87 and CLIK-1 are different in their ability to bundle actin filaments. In this study, I extended comparison between UNC-87 and CLIK-1 and found additional differences in vitro and in vivo. Although UNC-87 and CLIK-1 bound to actin filaments similarly, UNC-87, but not CLIK-1, bound to myosin and inhibited actomyosin ATPase in vitro. In striated muscle, UNC-87 and CLIK-1 were segregated into different subregions within sarcomeric actin filaments. CLIK-1 was concentrated near the actin pointed ends, whereas UNC-87 was enriched toward the actin barbed ends. Restricted localization of UNC-87 was not altered in a clik-1-null mutant, suggesting that their segregated localization is not due to competition between the two related proteins. These results suggest that the two calponin-related proteins have both common and distinct roles in regulating actin filaments.
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Affiliation(s)
- Shoichiro Ono
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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7
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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: 23] [Impact Index Per Article: 23.0] [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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8
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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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9
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Rajan S, Terman JR, Reisler E. MICAL-mediated oxidation of actin and its effects on cytoskeletal and cellular dynamics. Front Cell Dev Biol 2023; 11:1124202. [PMID: 36875759 PMCID: PMC9982024 DOI: 10.3389/fcell.2023.1124202] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 02/02/2023] [Indexed: 02/19/2023] Open
Abstract
Actin and its dynamic structural remodelings are involved in multiple cellular functions, including maintaining cell shape and integrity, cytokinesis, motility, navigation, and muscle contraction. Many actin-binding proteins regulate the cytoskeleton to facilitate these functions. Recently, actin's post-translational modifications (PTMs) and their importance to actin functions have gained increasing recognition. The MICAL family of proteins has emerged as important actin regulatory oxidation-reduction (Redox) enzymes, influencing actin's properties both in vitro and in vivo. MICALs specifically bind to actin filaments and selectively oxidize actin's methionine residues 44 and 47, which perturbs filaments' structure and leads to their disassembly. This review provides an overview of the MICALs and the impact of MICAL-mediated oxidation on actin's properties, including its assembly and disassembly, effects on other actin-binding proteins, and on cells and tissue systems.
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Affiliation(s)
- Sudeepa Rajan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, United States
| | - Jonathan R. Terman
- Departments of Neuroscience and Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, United States
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
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10
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Pimm ML, Liu X, Tuli F, Heritz J, Lojko A, Henty-Ridilla JL. Visualizing molecules of functional human profilin. eLife 2022; 11:e76485. [PMID: 35666129 PMCID: PMC9249392 DOI: 10.7554/elife.76485] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 06/06/2022] [Indexed: 11/20/2022] Open
Abstract
Profilin-1 (PFN1) is a cytoskeletal protein that regulates the dynamics of actin and microtubule assembly. Thus, PFN1 is essential for the normal division, motility, and morphology of cells. Unfortunately, conventional fusion and direct labeling strategies compromise different facets of PFN1 function. As a consequence, the only methods used to determine known PFN1 functions have been indirect and often deduced in cell-free biochemical assays. We engineered and characterized two genetically encoded versions of tagged PFN1 that behave identical to each other and the tag-free protein. In biochemical assays purified proteins bind to phosphoinositide lipids, catalyze nucleotide exchange on actin monomers, stimulate formin-mediated actin filament assembly, and bound tubulin dimers (kD = 1.89 µM) to impact microtubule dynamics. In PFN1-deficient mammalian cells, Halo-PFN1 or mApple-PFN1 (mAp-PEN1) restored morphological and cytoskeletal functions. Titrations of self-labeling Halo-ligands were used to visualize molecules of PFN1. This approach combined with specific function-disrupting point-mutants (Y6D and R88E) revealed PFN1 bound to microtubules in live cells. Cells expressing the ALS-associated G118V disease variant did not associate with actin filaments or microtubules. Thus, these tagged PFN1s are reliable tools for studying the dynamic interactions of PFN1 with actin or microtubules in vitro as well as in important cell processes or disease-states.
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Affiliation(s)
- Morgan L Pimm
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical UniversitySyracuseUnited States
| | - Xinbei Liu
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical UniversitySyracuseUnited States
| | - Farzana Tuli
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical UniversitySyracuseUnited States
| | - Jennifer Heritz
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical UniversitySyracuseUnited States
| | - Ashley Lojko
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical UniversitySyracuseUnited States
| | - Jessica L Henty-Ridilla
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical UniversitySyracuseUnited States
- Department of Neuroscience and Physiology, SUNY Upstate Medical UniversitySyracuseUnited States
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11
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Tilburg J, Becker IC, Italiano JE. Don't you forget about me(gakaryocytes). Blood 2022; 139:3245-3254. [PMID: 34582554 PMCID: PMC9164737 DOI: 10.1182/blood.2020009302] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/08/2021] [Indexed: 11/20/2022] Open
Abstract
Platelets (small, anucleate cell fragments) derive from large precursor cells, megakaryocytes (MKs), that reside in the bone marrow. MKs emerge from hematopoietic stem cells in a complex differentiation process that involves cytoplasmic maturation, including the formation of the demarcation membrane system, and polyploidization. The main function of MKs is the generation of platelets, which predominantly occurs through the release of long, microtubule-rich proplatelets into vessel sinusoids. However, the idea of a 1-dimensional role of MKs as platelet precursors is currently being questioned because of advances in high-resolution microscopy and single-cell omics. On the one hand, recent findings suggest that proplatelet formation from bone marrow-derived MKs is not the only mechanism of platelet production, but that it may also occur through budding of the plasma membrane and in distant organs such as lung or liver. On the other hand, novel evidence suggests that MKs not only maintain physiological platelet levels but further contribute to bone marrow homeostasis through the release of extracellular vesicles or cytokines, such as transforming growth factor β1 or platelet factor 4. The notion of multitasking MKs was reinforced in recent studies by using single-cell RNA sequencing approaches on MKs derived from adult and fetal bone marrow and lungs, leading to the identification of different MK subsets that appeared to exhibit immunomodulatory or secretory roles. In the following article, novel insights into the mechanisms leading to proplatelet formation in vitro and in vivo will be reviewed and the hypothesis of MKs as immunoregulatory cells will be critically discussed.
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Affiliation(s)
- Julia Tilburg
- Vascular Biology Program, Boston Children's Hospital, Boston, MA
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12
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Banerjee DS, Banerjee S. Emergence and maintenance of variable-length actin filaments in a limiting pool of building blocks. Biophys J 2022; 121:2436-2448. [PMID: 35598045 DOI: 10.1016/j.bpj.2022.05.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 04/10/2022] [Accepted: 05/13/2022] [Indexed: 11/16/2022] Open
Abstract
Actin is one of the key structural components of the eukaryotic cytoskeleton that regulates cellular architecture and mechanical properties. Dynamic regulation of actin filament length and organization is essential for the control of many physiological processes including cell adhesion, motility and division. While previous studies have mostly focused on the mechanisms controlling the mean length of individual actin filaments, it remains poorly understood how distinct actin filament populations in cells maintain different lengths using the same set of molecular building blocks. Here we develop a theoretical model for the length regulation of multiple actin filaments by nucleation and growth rate modulation by actin binding proteins in a limiting pool of monomers. We first show that spontaneous nucleation of actin filaments naturally leads to heterogeneities in filament length distribution. We then investigate the effects of filament growth inhibition by capping proteins and growth promotion by formin proteins on filament length distribution. We find that filament length heterogeneity can be increased by growth inhibition, whereas growth promoters do not significantly affect length heterogeneity. Interestingly, a competition between filament growth inhibitors and growth promoters can give rise to bimodal filament length distribution as well as a highly heterogeneous length distribution with large statistical dispersion. We quantitatively predict how heterogeneity in actin filament length can be modulated by tuning F-actin nucleation and growth rates in order to create distinct filament subpopulations with different lengths. SIGNIFICANCE: Actin filaments organize into different functional network architectures within eukaryotic cells. To maintain distinct actin network architectures, it is essential to regulate the lengths of actin filaments. While the mechanisms controlling the lengths of individual actin filaments have been extensively studied, the regulation of length heterogeneity in actin filament populations is not well understood. Here we show that the modulation of actin filament growth and nucleation rates by actin binding proteins can regulate actin length distribution and create distinct sub-populations with different lengths. In particular, by tuning concentrations of formin, profilin and capping proteins, various aspects of actin filament length distribution can be controlled. Insights gained from our results may have significant implications for the regulation of actin filament length heterogeneity and architecture within a cell.
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Affiliation(s)
- Deb Sankar Banerjee
- Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213, USA
| | - Shiladitya Banerjee
- Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213, USA
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13
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Gao J, Nakamura F. Actin-Associated Proteins and Small Molecules Targeting the Actin Cytoskeleton. Int J Mol Sci 2022; 23:2118. [PMID: 35216237 PMCID: PMC8880164 DOI: 10.3390/ijms23042118] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 02/06/2023] Open
Abstract
Actin-associated proteins (AAPs) act on monomeric globular actin (G-actin) and polymerized filamentous actin (F-actin) to regulate their dynamics and architectures which ultimately control cell movement, shape change, division; organelle localization and trafficking. Actin-binding proteins (ABPs) are a subset of AAPs. Since actin was discovered as a myosin-activating protein (hence named actin) in 1942, the protein has also been found to be expressed in non-muscle cells, and numerous AAPs continue to be discovered. This review article lists all of the AAPs discovered so far while also allowing readers to sort the list based on the names, sizes, functions, related human diseases, and the dates of discovery. The list also contains links to the UniProt and Protein Atlas databases for accessing further, related details such as protein structures, associated proteins, subcellular localization, the expression levels in cells and tissues, mutations, and pathology. Because the actin cytoskeleton is involved in many pathological processes such as tumorigenesis, invasion, and developmental diseases, small molecules that target actin and AAPs which hold potential to treat these diseases are also listed.
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Affiliation(s)
| | - Fumihiko Nakamura
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China;
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14
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Liu X, Pimm ML, Haarer B, Brawner AT, Henty-Ridilla JL. Biochemical characterization of actin assembly mechanisms with ALS-associated profilin variants. Eur J Cell Biol 2022; 101:151212. [PMID: 35248815 PMCID: PMC10163920 DOI: 10.1016/j.ejcb.2022.151212] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 12/26/2022] Open
Abstract
Eight separate mutations in the actin-binding protein profilin-1 have been identified as a rare cause of amyotrophic lateral sclerosis (ALS). Profilin is essential for many neuronal cell processes through its regulation of lipids, nuclear signals, and cytoskeletal dynamics, including actin filament assembly. Direct interactions between profilin and actin monomers inhibit actin filament polymerization. In contrast, profilin can also stimulate polymerization by simultaneously binding actin monomers and proline-rich tracts found in other proteins. Whether the ALS-associated mutations in profilin compromise these actin assembly functions is unclear. We performed a quantitative biochemical comparison of the direct and formin mediated impact for the eight ALS-associated profilin variants on actin assembly using classic protein-binding and single-filament microscopy assays. We determined that the binding constant of each profilin for actin monomers generally correlates with the actin nucleation strength associated with each ALS-related profilin. In the presence of formin, the A20T, R136W, Q139L, and C71G variants failed to activate the elongation phase of actin assembly. This diverse range of formin-activities is not fully explained through profilin-poly-L-proline (PLP) interactions, as all ALS-associated variants bind a formin-derived PLP peptide with similar affinities. However, chemical denaturation experiments suggest that the folding stability of these profilins impact some of these effects on actin assembly. Thus, changes in profilin protein stability and alterations in actin filament polymerization may both contribute to the profilin-mediated actin disruptions in ALS.
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Affiliation(s)
- Xinbei Liu
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Morgan L Pimm
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Brian Haarer
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Andrew T Brawner
- Department of Neuroscience & Physiology, 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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15
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Zweifel ME, Sherer LA, Mahanta B, Courtemanche N. Nucleation limits the lengths of actin filaments assembled by formin. Biophys J 2021; 120:4442-4456. [PMID: 34506773 DOI: 10.1016/j.bpj.2021.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/06/2021] [Accepted: 09/02/2021] [Indexed: 10/24/2022] Open
Abstract
Formins stimulate actin polymerization by promoting both filament nucleation and elongation. Because nucleation and elongation draw upon a common pool of actin monomers, the rate at which each reaction proceeds influences the other. This interdependent mechanism determines the number of filaments assembled over the course of a polymerization reaction, as well as their equilibrium lengths. In this study, we used kinetic modeling and in vitro polymerization reactions to dissect the contributions of filament nucleation and elongation to the process of formin-mediated actin assembly. We found that the rates of nucleation and elongation evolve over the course of a polymerization reaction. The period over which each process occurs is a key determinant of the total number of filaments that are assembled, as well as their average lengths at equilibrium. Inclusion of formin in polymerization reactions speeds filament nucleation, thus increasing the number and shortening the lengths of filaments that are assembled over the course of the reaction. Modulation of the elongation rate produces modest changes in the equilibrium lengths of formin-bound filaments. However, the dependence of filament length on the elongation rate is limited by the number of filament ends generated via formin's nucleation activity. Sustained elongation of small numbers of formin-bound filaments, therefore, requires inhibition of nucleation via monomer sequestration and a low concentration of activated formin. Our results underscore the mechanistic advantage for keeping formin's nucleation efficiency relatively low in cells, where unregulated actin assembly would produce deleterious effects on cytoskeletal dynamics. Under these conditions, differences in the elongation rates mediated by formin isoforms are most likely to impact the kinetics of actin assembly.
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Affiliation(s)
- Mark E Zweifel
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota
| | - Laura A Sherer
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota
| | - Biswaprakash Mahanta
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota
| | - Naomi Courtemanche
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota.
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16
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Grintsevich EE, Ahmed G, Ginosyan AA, Wu H, Rich SK, Reisler E, Terman JR. Profilin and Mical combine to impair F-actin assembly and promote disassembly and remodeling. Nat Commun 2021; 12:5542. [PMID: 34545088 PMCID: PMC8452626 DOI: 10.1038/s41467-021-25781-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 08/24/2021] [Indexed: 11/30/2022] Open
Abstract
Cellular events require the spatiotemporal interplay between actin assembly and actin disassembly. Yet, how different factors promote the integration of these two opposing processes is unclear. In particular, cellular monomeric (G)-actin is complexed with profilin, which inhibits spontaneous actin nucleation but fuels actin filament (F-actin) assembly by elongation-promoting factors (formins, Ena/VASP). In contrast, site-specific F-actin oxidation by Mical promotes F-actin disassembly and release of polymerization-impaired Mical-oxidized (Mox)-G-actin. Here we find that these two opposing processes connect with one another to orchestrate actin/cellular remodeling. Specifically, we find that profilin binds Mox-G-actin, yet these complexes do not fuel elongation factors’-mediated F-actin assembly, but instead inhibit polymerization and promote further Mox-F-actin disassembly. Using Drosophila as a model system, we show that similar profilin–Mical connections occur in vivo – where they underlie F-actin/cellular remodeling that accompanies Semaphorin–Plexin cellular/axon repulsion. Thus, profilin and Mical combine to impair F-actin assembly and promote F-actin disassembly, while concomitantly facilitating cellular remodeling and plasticity. Actin-based structures in cells and tissues are built and maintained through a poorly understood balance between assembly and disassembly. Here, our findings provide insights into how factors known to promote these opposing effects dynamically integrate to shape cells and tissue systems.
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Affiliation(s)
- Elena E Grintsevich
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA. .,Department of Chemistry and Biochemistry, California State University, Long Beach (CSULB), Long Beach, CA, 90840, USA.
| | - Giasuddin Ahmed
- Departments of Neuroscience and Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Anush A Ginosyan
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Heng Wu
- Departments of Neuroscience and Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Shannon K Rich
- Departments of Neuroscience and Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA. .,Molecular Biology Institute, UCLA, Los Angeles, CA, 90095, USA.
| | - Jonathan R Terman
- Departments of Neuroscience and Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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17
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Gibieža P, Petrikaitė V. The regulation of actin dynamics during cell division and malignancy. Am J Cancer Res 2021; 11:4050-4069. [PMID: 34659876 PMCID: PMC8493394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/29/2021] [Indexed: 06/13/2023] Open
Abstract
Actin is the most abundant protein in almost all the eukaryotic cells. Actin amino acid sequences are highly conserved and have not changed a lot during the progress of evolution, varying by no more than 20% in the completely different species, such as humans and algae. The network of actin filaments plays a crucial role in regulating cells' cytoskeleton that needs to undergo dynamic tuning and structural changes in order for various functional processes, such as cell motility, migration, adhesion, polarity establishment, cell growth and cell division, to take place in live cells. Owing to its fundamental role in the cell, actin is a prominent regulator of cell division, a process, whose success directly depends on morphological changes of actin cytoskeleton and correct segregation of duplicated chromosomes. Disorganization of actin framework during the last stage of cell division, known as cytokinesis, can lead to multinucleation and formation of polyploidy in post-mitotic cells, eventually developing into cancer. In this review, we will cover the principles of actin regulation during cell division and discuss how the control of actin dynamics is altered during the state of malignancy.
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Affiliation(s)
- Paulius Gibieža
- Laboratory of Drug Targets Histopathology, Institute of Cardiology, Lithuanian University of Health Sciences Kaunas, LT-50162, Lithuania
| | - Vilma Petrikaitė
- Laboratory of Drug Targets Histopathology, Institute of Cardiology, Lithuanian University of Health Sciences Kaunas, LT-50162, Lithuania
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18
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Murk K, Ornaghi M, Schiweck J. Profilin Isoforms in Health and Disease - All the Same but Different. Front Cell Dev Biol 2021; 9:681122. [PMID: 34458253 PMCID: PMC8387879 DOI: 10.3389/fcell.2021.681122] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 07/12/2021] [Indexed: 12/11/2022] Open
Abstract
Profilins are small actin binding proteins, which are structurally conserved throughout evolution. They are probably best known to promote and direct actin polymerization. However, they also participate in numerous cell biological processes beyond the roles typically ascribed to the actin cytoskeleton. Moreover, most complex organisms express several profilin isoforms. Their cellular functions are far from being understood, whereas a growing number of publications indicate that profilin isoforms are involved in the pathogenesis of various diseases. In this review, we will provide an overview of the profilin family and "typical" profilin properties including the control of actin dynamics. We will then discuss the profilin isoforms of higher animals in detail. In terms of cellular functions, we will focus on the role of Profilin 1 (PFN1) and Profilin 2a (PFN2a), which are co-expressed in the central nervous system. Finally, we will discuss recent findings that link PFN1 and PFN2a to neurological diseases, such as amyotrophic lateral sclerosis (ALS), Fragile X syndrome (FXS), Huntington's disease and spinal muscular atrophy (SMA).
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Affiliation(s)
- Kai Murk
- Institute of Biochemistry, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Marta Ornaghi
- Institute of Biochemistry, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Juliane Schiweck
- Institute of Biochemistry, Charité Universitätsmedizin Berlin, Berlin, Germany
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19
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Application of proteomic to investigate the different degrees of meat tenderness in Nellore breed. J Proteomics 2021; 248:104331. [PMID: 34303863 DOI: 10.1016/j.jprot.2021.104331] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 06/02/2021] [Accepted: 07/11/2021] [Indexed: 12/23/2022]
Abstract
This study describes the association between meat tenderness and abundance of soluble muscle proteins in Nellore bulls (Bos indicus) using a proteomic approach. We evaluated shear force (SF) of Longissimus thoracis muscle 24 h after slaughter and selected three experimental groups of animals with moderately tender (TE; SF = 3.9 ± 0.7 kg), moderately tough (TO; SF = 5.6 ± 0.7 kg) and very tough meat (TO+; SF = 7.9 ± 1.4 kg). Proteome was investigated by two-dimensional electrophoresis (2D-PAGE) in combination with electrospray ionization-tandem mass spectrometry (ESI-MS/MS). The metabolic proteins triosephosphate isomerase (TPI1) and phosphoglucomutase 1 (PGM1), the structural protein profilin 1 (PFN1), and cytosol aminopeptidase (LAP3) were up-regulated (P < 0.05) in the TE meat group when compared to the TO and TO+ groups. Actin structural proteins (ACTA1, ACTB, and ACTG1), the oxidative stress protein peroxiredoxin (PRDX6, PRDX2, PRDX1, and PARK7), heat shock protein isoforms, and co-chaperones (CDC37 and STIP1) were up-regulated (P < 0.05) in the TO and TO+ meat groups. In addition, we also identified proteins PFN1, LAP3, PRDX1, PRDX2, HSPD1, and ARHGDIA to be associated with beef tenderness. The results reported herein demonstrated that meat tenderness in Nellore cattle depends on the modulation and expression of a set of proteins involved in different biological pathways. SIGNIFICANCE: The manuscript entitled "Application of proteomic to investigate the different degrees of meat tenderness in Nellore breed" describes a classical proteomics work using two-dimensional gel electrophoresis (2D-PAGE), followed by mass spectrometry coupled to electrospray ionization ion trap (ESI-MS/MS) in order to understand the biochemical engineering involved in the process of meat tenderness. We evaluated shear force (SF) of Longissimus thoracis muscle samples of Nellore cattle (n = 90) and select three experimental groups of animals with moderately tender (TE; SF = 3.9 ± 0.7), moderately tough (TO; SF = 5.6 ± 0.7) and very tough meat (TO+; SF = 7.9 ± 1.4). The proteomic approach allowed observing that meat tenderness is influenced by structural proteins (ACTA1, ACTG1, ACTB, MYL1 and PFN1), co-chaperones (CDC37 and STIP1), heat shock proteins (HSP90AA1, HSP90AB1, HSPD1, HSPA1L, HSPA1A and HSPB1), regulatory protein (ARHGDIA), metabolic proteins (TPI1 and PGM1) and oxidative stress proteins (PRDX1, PRDX2, PRDX6, PARK7). Our results suggest that meat tenderness in Nellore depends on the modulation and expression of a set of proteins involved in different biological pathways.
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20
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Tabatabai AP, Seara DS, Tibbs J, Yadav V, Linsmeier I, Murrell MP. Detailed Balance Broken by Catch Bond Kinetics Enables Mechanical-Adaptation in Active Materials. ADVANCED FUNCTIONAL MATERIALS 2021; 31:2006745. [PMID: 34393691 PMCID: PMC8357268 DOI: 10.1002/adfm.202006745] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Indexed: 05/04/2023]
Abstract
Unlike nearly all engineered materials which contain bonds that weaken under load, biological materials contain "catch" bonds which are reinforced under load. Consequently, materials, such as the cell cytoskeleton, can adapt their mechanical properties in response to their state of internal, non-equilibrium (active) stress. However, how large-scale material properties vary with the distance from equilibrium is unknown, as are the relative roles of active stress and binding kinetics in establishing this distance. Through course-grained molecular dynamics simulations, the effect of breaking of detailed balance by catch bonds on the accumulation and dissipation of energy within a model of the actomyosin cytoskeleton is explored. It is found that the extent to which detailed balance is broken uniquely determines a large-scale fluid-solid transition with characteristic time-reversal symmetries. The transition depends critically on the strength of the catch bond, suggesting that active stress is necessary but insufficient to mount an adaptive mechanical response.
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Affiliation(s)
- Alan Pasha Tabatabai
- Department of Biomedical Engineering, Yale University, 55 Prospect Street, New Haven, CT 06511, USA; Systems Biology Institute, Yale University, 850 West Campus Drive, West Haven, CT 06516, USA
| | - Daniel S Seara
- Systems Biology Institute, Yale University, 850 West Campus Drive, West Haven, CT 06516, USA; Department of Physics, Yale University, 217 Prospect Street, New Haven, CT 06511, USA
| | - Joseph Tibbs
- Department of Physics, University of Northern Iowa, Cedar Falls, IA 50614, USA
| | - Vikrant Yadav
- Department of Biomedical Engineering, Yale University, 55 Prospect Street, New Haven, CT 06511, USA; Systems Biology Institute, Yale University, 850 West Campus Drive, West Haven, CT 06516, USA
| | - Ian Linsmeier
- Department of Biomedical Engineering, Yale University, 55 Prospect Street, New Haven, CT 06511, USA; Systems Biology Institute, Yale University, 850 West Campus Drive, West Haven, CT 06516, USA
| | - Michael P Murrell
- Department of Biomedical Engineering, Yale University, 55 Prospect Street, New Haven, CT 06511, USA; Systems Biology Institute, Yale University, 850 West Campus Drive, West Haven, CT 06516, USA; Department of Physics, Yale University, 217 Prospect Street, New Haven, CT 06511, USA
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21
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van Haastert PJM. Unified control of amoeboid pseudopod extension in multiple organisms by branched F-actin in the front and parallel F-actin/myosin in the cortex. PLoS One 2020; 15:e0243442. [PMID: 33296414 PMCID: PMC7725310 DOI: 10.1371/journal.pone.0243442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023] Open
Abstract
The trajectory of moving eukaryotic cells depends on the kinetics and direction of extending pseudopods. The direction of pseudopods has been well studied to unravel mechanisms for chemotaxis, wound healing and inflammation. However, the kinetics of pseudopod extension-when and why do pseudopods start and stop- is equally important, but is largely unknown. Here the START and STOP of about 4000 pseudopods was determined in four different species, at four conditions and in nine mutants (fast amoeboids Dictyostelium and neutrophils, slow mesenchymal stem cells, and fungus B.d. chytrid with pseudopod and a flagellum). The START of a first pseudopod is a random event with a probability that is species-specific (23%/s for neutrophils). In all species and conditions, the START of a second pseudopod is strongly inhibited by the extending first pseudopod, which depends on parallel filamentous actin/myosin in the cell cortex. Pseudopods extend at a constant rate by polymerization of branched F-actin at the pseudopod tip, which requires the Scar complex. The STOP of pseudopod extension is induced by multiple inhibitory processes that evolve during pseudopod extension and mainly depend on the increasing size of the pseudopod. Surprisingly, no differences in pseudopod kinetics are detectable between polarized, unpolarized or chemotactic cells, and also not between different species except for small differences in numerical values. This suggests that the analysis has uncovered the fundament of cell movement with distinct roles for stimulatory branched F-actin in the protrusion and inhibitory parallel F-actin in the contractile cortex.
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22
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Zweifel ME, Courtemanche N. Profilin's Affinity for Formin Regulates the Availability of Filament Ends for Actin Monomer Binding. J Mol Biol 2020; 432:166688. [PMID: 33289668 DOI: 10.1016/j.jmb.2020.10.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/05/2020] [Accepted: 10/18/2020] [Indexed: 12/20/2022]
Abstract
Nucleation-promoting proteins tightly regulate actin polymerization in cells. Whereas many of these proteins bind actin monomers directly, formins use the actin-binding protein profilin to dynamically load actin monomers onto their flexible Formin Homology 1 (FH1) domains. Following binding, FH1 domains deliver profilin-actin complexes to filament ends. To investigate profilin's role as an adaptor protein in formin-mediated elongation, we engineered a chimeric formin that binds actin monomers directly via covalent attachment of profilin to its binding site in the formin. This formin mediates slow filament elongation owing to a high probability of profilin binding at filament ends. Varying the position at which profilin is tethered to the formin alters the elongation rate by modulating profilin occupancy at the filament end. By regulating the availability of the barbed end, we propose that profilin binding establishes a secondary point of control over the rate of filament elongation mediated by formins. Profilin's differential affinities for actin monomers, barbed ends and polyproline are thus tuned to adaptively bridge actin and formins and optimize the rate of actin polymerization.
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Affiliation(s)
- Mark E Zweifel
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Naomi Courtemanche
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.
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23
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Ree R, Kind L, Kaziales A, Varland S, Dai M, Richter K, Drazic A, Arnesen T. PFN2 and NAA80 cooperate to efficiently acetylate the N-terminus of actin. J Biol Chem 2020; 295:16713-16731. [PMID: 32978259 PMCID: PMC7864067 DOI: 10.1074/jbc.ra120.015468] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/22/2020] [Indexed: 12/01/2022] Open
Abstract
The actin cytoskeleton is of profound importance to cell shape, division, and intracellular force generation. Profilins bind to globular (G-)actin and regulate actin filament formation. Although profilins are well-established actin regulators, the distinct roles of the dominant profilin, profilin 1 (PFN1), versus the less abundant profilin 2 (PFN2) remain enigmatic. In this study, we use interaction proteomics to discover that PFN2 is an interaction partner of the actin N-terminal acetyltransferase NAA80, and further confirm this by analytical ultracentrifugation. Enzyme assays with NAA80 and different profilins demonstrate that PFN2 binding specifically increases the intrinsic catalytic activity of NAA80. NAA80 binds PFN2 through a proline-rich loop, deletion of which abrogates PFN2 binding. Small-angle X-ray scattering shows that NAA80, actin, and PFN2 form a ternary complex and that NAA80 has partly disordered regions in the N-terminus and the proline-rich loop, the latter of which is partly ordered upon PFN2 binding. Furthermore, binding of PFN2 to NAA80 via the proline-rich loop promotes binding between the globular domains of actin and NAA80, and thus acetylation of actin. However, the majority of cellular NAA80 is stably bound to PFN2 and not to actin, and we propose that this complex acetylates G-actin before it is incorporated into filaments. In conclusion, we reveal a functionally specific role of PFN2 as a stable interactor and regulator of the actin N-terminal acetyltransferase NAA80, and establish the modus operandi for NAA80-mediated actin N-terminal acetylation, a modification with a major impact on cytoskeletal dynamics.
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Affiliation(s)
- Rasmus Ree
- Department of Biomedicine, University of Bergen, Bergen, Norway.
| | - Laura Kind
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Anna Kaziales
- Department of Chemistry, Technische Universität München, Garching, Germany
| | - Sylvia Varland
- Department of Biomedicine, University of Bergen, Bergen, Norway; Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Minglu Dai
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Klaus Richter
- Department of Chemistry, Technische Universität München, Garching, Germany
| | - Adrian Drazic
- Department of Biomedicine, University of Bergen, Bergen, Norway.
| | - Thomas Arnesen
- Department of Biomedicine, University of Bergen, Bergen, Norway; Department of Biological Sciences, University of Bergen, Bergen, Norway; Department of Surgery, Haukeland University Hospital, Bergen, Norway
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24
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Structural basis for polarized elongation of actin filaments. Proc Natl Acad Sci U S A 2020; 117:30458-30464. [PMID: 33199648 DOI: 10.1073/pnas.2011128117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Actin filaments elongate and shorten much faster at their barbed end than their pointed end, but the molecular basis of this difference has not been understood. We use all-atom molecular dynamics simulations to investigate the properties of subunits at both ends of the filament. The terminal subunits tend toward conformations that resemble actin monomers in solution, while contacts with neighboring subunits progressively flatten the conformation of internal subunits. At the barbed end the terminal subunit is loosely tethered by its DNase-1 loop to the third subunit, because its monomer-like conformation precludes stabilizing contacts with the penultimate subunit. The motions of the terminal subunit make the partially flattened penultimate subunit accessible for binding monomers. At the pointed end, unique contacts between the penultimate and terminal subunits are consistent with existing cryogenic electron microscopic (cryo-EM) maps, limit binding to incoming monomers, and flatten the terminal subunit, which likely promotes ATP hydrolysis and rapid phosphate release. These structures explain the distinct polymerization kinetics of the two ends.
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25
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Xie Y, Loh ZY, Xue J, Zhou F, Sun J, Qiao Z, Jin S, Deng Y, Li H, Wang Y, Lu L, Gao Y, Miao Y. Orchestrated actin nucleation by the Candida albicans polarisome complex enables filamentous growth. J Biol Chem 2020; 295:14840-14854. [PMID: 32848016 DOI: 10.1074/jbc.ra120.013890] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/09/2020] [Indexed: 12/29/2022] Open
Abstract
Candida albicans is a dimorphic fungus that converts from a yeast form to a hyphae form during infection. This switch requires the formation of actin cable to coordinate polarized cell growth. It's known that nucleation of this cable requires a multiprotein complex localized at the tip called the polarisome, but the mechanisms underpinning this process were unclear. Here, we found that C. albicans Aip5, a homolog of polarisome component ScAip5 in Saccharomyces cerevisiae that nucleates actin polymerization and synergizes with the formin ScBni1, regulates actin assembly and hyphae growth synergistically with other polarisome proteins Bni1, Bud6, and Spa2. The C terminus of Aip5 binds directly to G-actin, Bni1, and the C-terminal of Bud6, which form the core of the nucleation complex to polymerize F-actin. Based on insights from structural biology and molecular dynamic simulations, we propose a possible complex conformation of the actin nucleation core, which provides cooperative positioning and supports the synergistic actin nucleation activity of a tri-protein complex Bni1-Bud6-Aip5. Together with known interactions of Bni1 with Bud6 and Aip5 in S. cerevisiae, our findings unravel molecular mechanisms of C. albicans by which the tri-protein complex coordinates the actin nucleation in actin cable assembly and hyphal growth, which is likely a conserved mechanism in different filamentous fungi and yeast.
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Affiliation(s)
- Ying Xie
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Zhi Yang Loh
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Jiao Xue
- School of Biological Sciences, Nanyang Technological University, Singapore; College of Life Science and Technology, Jinan University, Guangzhou, China; The College of Life Sciences, Northwest University, Xi'an, China
| | - Feng Zhou
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Jialin Sun
- School of Biological Sciences, Nanyang Technological University, Singapore; Institute of Molecular and Cell Biology, A*STAR, Singapore
| | - Zhu Qiao
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Shengyang Jin
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Yinyue Deng
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Guangzhou, China
| | - Hongye Li
- College of Life Science and Technology, Jinan University, Guangzhou, China
| | - Yue Wang
- Institute of Molecular and Cell Biology, A*STAR, Singapore
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Yonggui Gao
- School of Biological Sciences, Nanyang Technological University, Singapore; Institute of Molecular and Cell Biology, A*STAR, Singapore; NTU Institute of Structural Biology, Nanyang Technological University, Nanyang Drive, Singapore
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, Singapore.
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26
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Pimm ML, Hotaling J, Henty-Ridilla JL. Profilin choreographs actin and microtubules in cells and cancer. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 355:155-204. [PMID: 32859370 PMCID: PMC7461721 DOI: 10.1016/bs.ircmb.2020.05.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Actin and microtubules play essential roles in aberrant cell processes that define and converge in cancer including: signaling, morphology, motility, and division. Actin and microtubules do not directly interact, however shared regulators coordinate these polymers. While many of the individual proteins important for regulating and choreographing actin and microtubule behaviors have been identified, the way these molecules collaborate or fail in normal or disease contexts is not fully understood. Decades of research focus on Profilin as a signaling molecule, lipid-binding protein, and canonical regulator of actin assembly. Recent reports demonstrate that Profilin also regulates microtubule dynamics and polymerization. Thus, Profilin can coordinate both actin and microtubule polymer systems. Here we reconsider the biochemical and cellular roles for Profilin with a focus on the essential cytoskeletal-based cell processes that go awry in cancer. We also explore how the use of model organisms has helped to elucidate mechanisms that underlie the regulatory essence of Profilin in vivo and in the context of disease.
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Affiliation(s)
- Morgan L Pimm
- Department of Cell and Developmental Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY, United States
| | - Jessica Hotaling
- Department of Cell and Developmental Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY, United States
| | - Jessica L Henty-Ridilla
- Department of Cell and Developmental Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY, United States; Department of Biochemistry and Molecular Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY, United States.
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27
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Le S, Yu M, Bershadsky A, Yan J. Mechanical regulation of formin-dependent actin polymerization. Semin Cell Dev Biol 2020; 102:73-80. [DOI: 10.1016/j.semcdb.2019.11.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/19/2019] [Accepted: 11/27/2019] [Indexed: 10/25/2022]
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28
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Moreau CA, Quadt KA, Piirainen H, Kumar H, Bhargav SP, Strauss L, Tolia NH, Wade RC, Spatz JP, Kursula I, Frischknecht F. A function of profilin in force generation during malaria parasite motility that is independent of actin binding. J Cell Sci 2020; 134:jcs233775. [PMID: 32034083 DOI: 10.1242/jcs.233775] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 01/06/2020] [Indexed: 01/20/2023] Open
Abstract
During transmission of malaria-causing parasites from mosquito to mammal, Plasmodium sporozoites migrate at high speed within the skin to access the bloodstream and infect the liver. This unusual gliding motility is based on retrograde flow of membrane proteins and highly dynamic actin filaments that provide short tracks for a myosin motor. Using laser tweezers and parasite mutants, we previously suggested that actin filaments form macromolecular complexes with plasma membrane-spanning adhesins to generate force during migration. Mutations in the actin-binding region of profilin, a near ubiquitous actin-binding protein, revealed that loss of actin binding also correlates with loss of force production and motility. Here, we show that different mutations in profilin, that do not affect actin binding in vitro, still generate lower force during Plasmodium sporozoite migration. Lower force generation inversely correlates with increased retrograde flow suggesting that, like in mammalian cells, the slow down of flow to generate force is the key underlying principle governing Plasmodium gliding motility.
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Affiliation(s)
- Catherine A Moreau
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Katharina A Quadt
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
- Department of Cellular Biophysics, Max Planck Institute for Medical Research and Laboratory of Biophysical Chemistry, Heidelberg University, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Henni Piirainen
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland
| | - Hirdesh Kumar
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110, USA
- Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance and Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Saligram P Bhargav
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland
| | - Léanne Strauss
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Niraj H Tolia
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Rebecca C Wade
- Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance and Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
- Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Joachim P Spatz
- Department of Cellular Biophysics, Max Planck Institute for Medical Research and Laboratory of Biophysical Chemistry, Heidelberg University, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Inari Kursula
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway
| | - Friedrich Frischknecht
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
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29
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Christensen JR, Craig EW, Glista MJ, Mueller DM, Li Y, Sees JA, Huang S, Suarez C, Mets LJ, Kovar DR, Avasthi P. Chlamydomonas reinhardtii formin FOR1 and profilin PRF1 are optimized for acute rapid actin filament assembly. Mol Biol Cell 2019; 30:3123-3135. [PMID: 31664873 PMCID: PMC6938247 DOI: 10.1091/mbc.e19-08-0463] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/10/2019] [Accepted: 10/24/2019] [Indexed: 12/18/2022] Open
Abstract
The regulated assembly of multiple filamentous actin (F-actin) networks from an actin monomer pool is important for a variety of cellular processes. Chlamydomonas reinhardtii is a unicellular green alga expressing a conventional and divergent actin that is an emerging system for investigating the complex regulation of actin polymerization. One actin network that contains exclusively conventional F-actin in Chlamydomonas is the fertilization tubule, a mating structure at the apical cell surface in gametes. In addition to two actin genes, Chlamydomonas expresses a profilin (PRF1) and four formin genes (FOR1-4), one of which (FOR1) we have characterized for the first time. We found that unlike typical profilins, PRF1 prevents unwanted actin assembly by strongly inhibiting both F-actin nucleation and barbed-end elongation at equimolar concentrations to actin. However, FOR1 stimulates the assembly of rapidly elongating actin filaments from PRF1-bound actin. Furthermore, for1 and prf1-1 mutants, as well as the small molecule formin inhibitor SMIFH2, prevent fertilization tubule formation in gametes, suggesting that polymerization of F-actin for fertilization tubule formation is a primary function of FOR1. Together, these findings indicate that FOR1 and PRF1 cooperate to selectively and rapidly assemble F-actin at the right time and place.
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Affiliation(s)
- Jenna R. Christensen
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
| | - Evan W. Craig
- Department of Anatomy and Cell Biology , University of Kansas Medical Center, Kansas City, KS 66103
| | - Michael J. Glista
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
| | - David M. Mueller
- Department of Anatomy and Cell Biology , University of Kansas Medical Center, Kansas City, KS 66103
| | - Yujie Li
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
| | - Jennifer A. Sees
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
| | - Shengping Huang
- Department of Ophthalmology, University of Kansas Medical Center, Kansas City, KS 66103
| | - Cristian Suarez
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
| | - Laurens J. Mets
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
| | - David R. Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637
| | - Prachee Avasthi
- Department of Anatomy and Cell Biology , University of Kansas Medical Center, Kansas City, KS 66103
- Department of Ophthalmology, University of Kansas Medical Center, Kansas City, KS 66103
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30
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Walter LM, Franz P, Lindner R, Tsiavaliaris G, Hensel N, Claus P. Profilin2a-phosphorylation as a regulatory mechanism for actin dynamics. FASEB J 2019; 34:2147-2160. [PMID: 31908005 DOI: 10.1096/fj.201901883r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/16/2019] [Accepted: 11/14/2019] [Indexed: 12/25/2022]
Abstract
Profilin is a major regulator of actin dynamics in multiple specific processes localized in different cellular compartments. This specificity is not only meditated by its binding to actin but also its interaction with phospholipids such as phosphatidylinositol (4,5)-bisphosphate (PIP2 ) at the membrane and a plethora of proteins containing poly-L-proline (PLP) stretches. These interactions are fine-tuned by posttranslational modifications such as phosphorylation. Several phospho-sites have already been identified for profilin1, the ubiquitously expressed isoform. However, little is known about the phosphorylation of profilin2a. Profilin2a is a neuronal isoform important for synapse function. Here, we identified several putative profilin2a phospho-sites in silico and tested recombinant phospho-mimetics with regard to their actin-, PLP-, and PIP2 -binding properties. Moreover, we assessed their impact on actin dynamics employing a pyrene-actin polymerization assay. Results indicate that distinct phospho-sites modulate specific profilin2a functions. We could identify a molecular switch site at serine residue 71 which completely abrogated actin binding-as well as other sites important for fine-tuning of different functions, for example, tyrosine 29 for PLP binding. Our findings suggest that differential profilin2a phosphorylation is a sensitive mechanism for regulating its neuronal functions. Moreover, the dysregulation of profilin2a phosphorylation may contribute to neurodegeneration.
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Affiliation(s)
- Lisa Marie Walter
- Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,Center of Systems Neuroscience, Hannover, Germany
| | - Peter Franz
- Institute of Cellular Biophysics, Hannover Medical School, Hannover, Germany
| | - Robert Lindner
- Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany
| | | | - Niko Hensel
- Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,Center of Systems Neuroscience, Hannover, Germany
| | - Peter Claus
- Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,Center of Systems Neuroscience, Hannover, Germany
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31
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Merino F, Pospich S, Raunser S. Towards a structural understanding of the remodeling of the actin cytoskeleton. Semin Cell Dev Biol 2019; 102:51-64. [PMID: 31836290 PMCID: PMC7221352 DOI: 10.1016/j.semcdb.2019.11.018] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 11/27/2019] [Accepted: 11/28/2019] [Indexed: 12/03/2022]
Abstract
Actin filaments (F-actin) are a key component of eukaryotic cells. Whether serving as a scaffold for myosin or using their polymerization to push onto cellular components, their function is always related to force generation. To control and fine-tune force production, cells have a large array of actin-binding proteins (ABPs) dedicated to control every aspect of actin polymerization, filament localization, and their overall mechanical properties. Although great advances have been made in our biochemical understanding of the remodeling of the actin cytoskeleton, the structural basis of this process is still being deciphered. In this review, we summarize our current understanding of this process. We outline how ABPs control the nucleation and disassembly, and how these processes are affected by the nucleotide state of the filaments. In addition, we highlight recent advances in the understanding of actomyosin force generation, and describe recent advances brought forward by the developments of electron cryomicroscopy.
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Affiliation(s)
- Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Sabrina Pospich
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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32
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Abstract
Actin polymerization is essential for cells to migrate, as well as for various cell biological processes such as cytokinesis and vesicle traffic. This brief review describes the mechanisms underlying its different roles and recent advances in our understanding. Actin usually requires "nuclei"-preformed actin filaments-to start polymerizing, but, once initiated, polymerization continues constitutively. The field therefore has a strong focus on nucleators, in particular the Arp2/3 complex and formins. These have different functions, are controlled by contrasting mechanisms, and generate alternate geometries of actin networks. The Arp2/3 complex functions only when activated by nucleation-promoting factors such as WASP, Scar/WAVE, WASH, and WHAMM and when binding to a pre-existing filament. Formins can be individually active but are usually autoinhibited. Each is controlled by different mechanisms and is involved in different biological roles. We also describe the processes leading to actin disassembly and their regulation and conclude with four questions whose answers are important for understanding actin dynamics but are currently unanswered.
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Affiliation(s)
- Simona Buracco
- Institute of Cancer Sciences, University of Glasgow, Bearsden, G61 1BD, UK
| | - Sophie Claydon
- Institute of Cancer Sciences, University of Glasgow, Bearsden, G61 1BD, UK
| | - Robert Insall
- Institute of Cancer Sciences, University of Glasgow, Bearsden, G61 1BD, UK
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33
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Adeli Koudehi M, Rutkowski DM, Vavylonis D. Organization of associating or crosslinked actin filaments in confinement. Cytoskeleton (Hoboken) 2019; 76:532-548. [PMID: 31525281 DOI: 10.1002/cm.21565] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 09/09/2019] [Accepted: 09/12/2019] [Indexed: 12/13/2022]
Abstract
A key factor of actin cytoskeleton organization in cells is the interplay between the dynamical properties of actin filaments and cell geometry, which restricts, confines and directs their orientation. Crosslinking interactions among actin filaments, together with geometrical cues and regulatory proteins can give rise to contractile rings in dividing cells and actin rings in neurons. Motivated by recent in vitro experiments, in this work we performed computer simulations to study basic aspects of the interplay between confinement and attractive interactions between actin filaments. We used a spring-bead model and Brownian dynamics to simulate semiflexible actin filaments that polymerize in a confining sphere with a rate proportional to the monomer concentration. We model crosslinking, or attraction through the depletion interaction, implicitly as an attractive short-range potential between filament beads. In confining geometries smaller than the persistence length of actin filaments, we show rings can form by curving of filaments of length comparable to, or longer than the confinement diameter. Rings form for optimal ranges of attractive interactions that exist in between open bundles, irregular loops, aggregated, and unbundled morphologies. The probability of ring formation is promoted by attraction to the confining sphere boundary and decreases for large radii and initial monomer concentrations, in agreement with prior experimental data. The model reproduces ring formation along the flat plane of oblate ellipsoids.
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34
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Funk J, Merino F, Venkova L, Heydenreich L, Kierfeld J, Vargas P, Raunser S, Piel M, Bieling P. Profilin and formin constitute a pacemaker system for robust actin filament growth. eLife 2019; 8:50963. [PMID: 31647411 PMCID: PMC6867828 DOI: 10.7554/elife.50963] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 10/24/2019] [Indexed: 12/19/2022] Open
Abstract
The actin cytoskeleton drives many essential biological processes, from cell morphogenesis to motility. Assembly of functional actin networks requires control over the speed at which actin filaments grow. How this can be achieved at the high and variable levels of soluble actin subunits found in cells is unclear. Here we reconstitute assembly of mammalian, non-muscle actin filaments from physiological concentrations of profilin-actin. We discover that under these conditions, filament growth is limited by profilin dissociating from the filament end and the speed of elongation becomes insensitive to the concentration of soluble subunits. Profilin release can be directly promoted by formin actin polymerases even at saturating profilin-actin concentrations. We demonstrate that mammalian cells indeed operate at the limit to actin filament growth imposed by profilin and formins. Our results reveal how synergy between profilin and formins generates robust filament growth rates that are resilient to changes in the soluble subunit concentration.
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Affiliation(s)
- Johanna Funk
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | | | - Jan Kierfeld
- Physics Department, TU Dortmund University, Dortmund, Germany
| | | | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
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35
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Brettle M, Stefen H, Djordjevic A, Fok SYY, Chan JW, van Hummel A, van der Hoven J, Przybyla M, Volkerling A, Ke YD, Delerue F, Ittner LM, Fath T. Developmental Expression of Mutant PFN1 in Motor Neurons Impacts Neuronal Growth and Motor Performance of Young and Adult Mice. Front Mol Neurosci 2019; 12:231. [PMID: 31611772 PMCID: PMC6776973 DOI: 10.3389/fnmol.2019.00231] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 09/10/2019] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease with limited treatment and no cure. Mutations in profilin 1 were identified as a cause of familial ALS (fALS) in 2012. We investigated the functional impact of mutant profilin 1 expression in spinal cords during mouse development. We developed a novel mouse model with the expression of profilin 1 C71G under the control of the Hb9 promoter, targeting expression to α-motor neurons in the spinal cord during development. Embryos of transgenic mice showed evidence of a significant reduction of brachial nerve diameter and a loss of Mendelian inheritance. Despite the lack of transgene expression, adult mice presented with significant motor deficits. Transgenic mice had a significant reduction in the number of motor neurons in the spinal cord. Further analysis of these motor neurons in aged transgenic mice revealed reduced levels of TDP-43 and ChAT expression. Although profilin 1 C71G was only expressed during development, adult mice presented with some ALS-associated pathology and motor symptoms. This study highlights the effect of profilin 1 during neurodevelopment and the impact that this may have in later ALS.
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Affiliation(s)
- Merryn Brettle
- School of Medical Sciences, Faculty of Medicine, UNSW Sydney, Randwick, NSW, Australia.,Biomedical Imaging Facility, Mark Wainwright Analytical Centre, UNSW Sydney, Randwick, NSW, Australia
| | - Holly Stefen
- Dementia Research Centre and Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Aleksandra Djordjevic
- School of Medical Sciences, Faculty of Medicine, UNSW Sydney, Randwick, NSW, Australia
| | - Sandra Y Y Fok
- School of Medical Sciences, Faculty of Medicine, UNSW Sydney, Randwick, NSW, Australia.,Biomedical Imaging Facility, Mark Wainwright Analytical Centre, UNSW Sydney, Randwick, NSW, Australia
| | - Josephine W Chan
- School of Medical Sciences, Faculty of Medicine, UNSW Sydney, Randwick, NSW, Australia
| | - Annika van Hummel
- Dementia Research Centre and Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Julia van der Hoven
- Dementia Research Centre and Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Magdalena Przybyla
- Dementia Research Centre and Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Alexander Volkerling
- School of Medical Sciences, Faculty of Medicine, UNSW Sydney, Randwick, NSW, Australia
| | - Yazi D Ke
- Dementia Research Centre and Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Fabien Delerue
- Dementia Research Centre and Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Lars M Ittner
- Dementia Research Centre and Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Thomas Fath
- School of Medical Sciences, Faculty of Medicine, UNSW Sydney, Randwick, NSW, Australia.,Dementia Research Centre and Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
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36
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Abstract
The shape of most animal cells is controlled by the actin cortex, a thin network of dynamic actin filaments (F-actin) situated just beneath the plasma membrane. The cortex is held far from equilibrium by both active stresses and polymer turnover: Molecular motors drive deformations required for cell morphogenesis, while actin-filament disassembly dynamics relax stress and facilitate cortical remodeling. While many aspects of actin-cortex mechanics are well characterized, a mechanistic understanding of how nonequilibrium actin turnover contributes to stress relaxation is still lacking. To address this, we developed a reconstituted in vitro system of entangled F-actin, wherein the steady-state length and turnover rate of F-actin are controlled by the actin regulatory proteins cofilin, profilin, and formin, which sever, recycle, and assemble filaments, respectively. Cofilin-mediated severing accelerates the turnover and spatial reorganization of F-actin, without significant changes to filament length. We demonstrate that cofilin-mediated severing is a single-timescale mode of stress relaxation that tunes the low-frequency viscosity over two orders of magnitude. These findings serve as the foundation for understanding the mechanics of more physiological F-actin networks with turnover and inform an updated microscopic model of single-filament turnover. They also demonstrate that polymer activity, in the form of ATP hydrolysis on F-actin coupled to nucleotide-dependent cofilin binding, is sufficient to generate a form of active matter wherein asymmetric filament disassembly preserves filament number despite sustained severing.
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37
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Chou SZ, Pollard TD. Mechanism of actin polymerization revealed by cryo-EM structures of actin filaments with three different bound nucleotides. Proc Natl Acad Sci U S A 2019; 116:4265-4274. [PMID: 30760599 PMCID: PMC6410863 DOI: 10.1073/pnas.1807028115] [Citation(s) in RCA: 131] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We used cryo-electron microscopy (cryo-EM) to reconstruct actin filaments with bound AMPPNP (β,γ-imidoadenosine 5'-triphosphate, an ATP analog, resolution 3.1 Å), ADP-Pi (ADP with inorganic phosphate, resolution 3.1 Å), or ADP (resolution 3.6 Å). Subunits in the three filaments have similar backbone conformations, so assembly rather than ATP hydrolysis or phosphate dissociation is responsible for their flattened conformation in filaments. Polymerization increases the rate of ATP hydrolysis by changing the positions of the side chains of Q137 and H161 in the active site. Flattening during assembly also promotes interactions along both the long-pitch and short-pitch helices. In particular, conformational changes in subdomain 3 open up multiple favorable interactions with the DNase-I binding loop in subdomain 2 of the adjacent subunit. Subunits at the barbed end of the filament are likely to be in this favorable conformation, while monomers are not. This difference explains why filaments grow faster at the barbed end than the pointed end. When phosphate dissociates from ADP-Pi-actin through a backdoor channel, the conformation of the C terminus changes so it distorts the DNase binding loop, which allows cofilin binding, and a network of interactions among S14, H73, G74, N111, R177, and G158 rearranges to open the phosphate release site.
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Affiliation(s)
- Steven Z Chou
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103
| | - Thomas D Pollard
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103;
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103
- Department of Cell Biology, Yale University, New Haven, CT 06520-8103
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38
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Mullins RD, Bieling P, Fletcher DA. From solution to surface to filament: actin flux into branched networks. Biophys Rev 2018; 10:1537-1551. [PMID: 30470968 DOI: 10.1007/s12551-018-0469-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 10/21/2018] [Indexed: 02/05/2023] Open
Abstract
The actin cytoskeleton comprises a set of filament networks that perform essential functions in eukaryotic cells. The idea that actin filaments incorporate monomers directly from solution forms both the "textbook picture" of filament elongation and a conventional starting point for quantitative modeling of cellular actin dynamics. Recent work, however, reveals that filaments created by two major regulators, the formins and the Arp2/3 complex, incorporate monomers delivered by nearby proteins. Specifically, actin enters Arp2/3-generated networks via binding sites on nucleation-promoting factors clustered on membrane surfaces. Here, we describe three functions of this surface-associated actin monomer pool: (1) regulating network density via product inhibition of the Arp2/3 complex, (2) accelerating filament elongation as a distributive polymerase, and (3) converting profilin-actin into a substrate for the Arp2/3 complex. These linked functions control the architecture of branched networks and explain how capping protein enhances their growth.
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Affiliation(s)
- R Dyche Mullins
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, UCSF School of Medicine, San Francisco, CA, USA.
| | - Peter Bieling
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Daniel A Fletcher
- Department of Bioengineering, University of California, Berkeley, CA, USA
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39
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Courtemanche N. Mechanisms of formin-mediated actin assembly and dynamics. Biophys Rev 2018; 10:1553-1569. [PMID: 30392063 DOI: 10.1007/s12551-018-0468-6] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 10/18/2018] [Indexed: 12/14/2022] Open
Abstract
Cellular viability requires tight regulation of actin cytoskeletal dynamics. Distinct families of nucleation-promoting factors enable the rapid assembly of filament nuclei that elongate and are incorporated into diverse and specialized actin-based structures. In addition to promoting filament nucleation, the formin family of proteins directs the elongation of unbranched actin filaments. Processive association of formins with growing filament ends is achieved through continuous barbed end binding of the highly conserved, dimeric formin homology (FH) 2 domain. In cooperation with the FH1 domain and C-terminal tail region, FH2 dimers mediate actin subunit addition at speeds that can dramatically exceed the rate of spontaneous assembly. Here, I review recent biophysical, structural, and computational studies that have provided insight into the mechanisms of formin-mediated actin assembly and dynamics.
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Affiliation(s)
- Naomi Courtemanche
- Department of Genetics, Cell and Developmental Biology, University of Minnesota, 420 Washington Ave SE, 6-130 MCB, Minneapolis, MN, 55455, USA.
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40
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Genomes of Asgard archaea encode profilins that regulate actin. Nature 2018; 562:439-443. [DOI: 10.1038/s41586-018-0548-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 08/23/2018] [Indexed: 11/08/2022]
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41
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Fujiwara I, Zweifel ME, Courtemanche N, Pollard TD. Latrunculin A Accelerates Actin Filament Depolymerization in Addition to Sequestering Actin Monomers. Curr Biol 2018; 28:3183-3192.e2. [PMID: 30270183 DOI: 10.1016/j.cub.2018.07.082] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 04/30/2018] [Accepted: 07/31/2018] [Indexed: 11/16/2022]
Abstract
Latrunculin A (LatA), a toxin from the red sea sponge Latrunculia magnifica, is the most widely used reagent to depolymerize actin filaments in experiments on live cells. LatA binds actin monomers and sequesters them from polymerization [1, 2]. Low concentrations of LatA result in rapid (tens of seconds) disassembly of actin filaments in animal [3] and yeast cells [2]. Depolymerization is usually assumed to result from sequestration of actin monomers. Our observations of single-muscle actin filaments by TIRF microscopy showed that LatA bound ATP-actin monomers with a higher affinity (Kd = 0.1 μM) than ADP-Pi-actin (Kd = 0.4 μM) or ADP-actin (Kd = 4.7 μM). LatA also slowly severed filaments and increased the depolymerization rate at both ends of filaments freshly assembled from ATP-actin to the rates of ADP-actin. This rate plateaued at LatA concentrations >60 μM. LatA did not change the depolymerization rates of ADP- actin filaments or ADP-Pi-actin filaments generated with 160 mM phosphate in the buffer. LatA did not increase the rate of phosphate release from bulk samples of filaments assembled from ATP-actin. Thermodynamic analysis showed that LatA binds weakly to actin filaments with a Kd >100 μM. We propose that concentrations of LatA much lower than this Kd promote phosphate dissociation only from both ends of filaments, resulting in depolymerization limited by the rate of ADP-actin dissociation. Thus, one must consider both rapid actin depolymerization and severing in addition to sequestering actin monomers when interpreting the effects of LatA on cells.
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Affiliation(s)
- Ikuko Fujiwara
- Frontier Research Institute for Materials Science, Nagoya Institute of Technology, Gokiso, Showa-ku, Nagoya 466-8555, Japan; Department of Molecular Cellular and Developmental Biology, Yale University, PO Box 208103, New Haven, CT 06520, USA.
| | - Mark E Zweifel
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Naomi Courtemanche
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Thomas D Pollard
- Department of Molecular Cellular and Developmental Biology, Yale University, PO Box 208103, New Haven, CT 06520, USA; Departments of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA; Department of Cell Biology, Yale University, New Haven, CT 06520, USA
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42
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Yu M, Le S, Efremov AK, Zeng X, Bershadsky A, Yan J. Effects of Mechanical Stimuli on Profilin- and Formin-Mediated Actin Polymerization. NANO LETTERS 2018; 18:5239-5247. [PMID: 29976069 DOI: 10.1021/acs.nanolett.8b02211] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Self-assembling actin filaments not only form the basis of the cytoskeleton network in cells but also are utilized as nanosized building blocks to make novel active matter in which the dynamic polymerization and depolymerization of actin filaments play a key role. Formins belong to a main family of actin nucleation factors that bind to the barbed end of actin filaments and regulate actin polymerization through an interaction with profilin. Due to actomyosin contractility and relative rotation between formin and actin filaments, formin-dependent actin polymerization is subject to force and rotation constraints. However, it remains unclear how force and rotation constraints affect formin-dependent actin polymerization in the presence of profilin. Here, we show that for rotation-unconstrained actin filaments, elongation is accelerated by both force and profilin. The combined effect leads to surprisingly fast actin elongation that can approach the diffusion-limited rate at forces of a few piconewtons. The elongation of rotation-constrained filaments is also accelerated by profilin but is insensitive to applied force. We show that FH2, the main actin binding domain, plays the primary mechanosensing role. Together, the findings not only significantly advance our understanding of the mechanochemical regulation of formin-mediated actin polymerization in cells but also can potentially be utilized to make novel actin-based active matter.
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Affiliation(s)
- Miao Yu
- Mechanobiology Institute, National University of Singapore , Singapore 117411
- Department of Physics , National University of Singapore , Singapore 117542
| | - Shimin Le
- Mechanobiology Institute, National University of Singapore , Singapore 117411
- Department of Physics , National University of Singapore , Singapore 117542
| | - Artem K Efremov
- Mechanobiology Institute, National University of Singapore , Singapore 117411
- Centre for Bioimaging Sciences , National University of Singapore , Singapore 117546
| | - Xiangjun Zeng
- Department of Physics , National University of Singapore , Singapore 117542
| | - Alexander Bershadsky
- Mechanobiology Institute, National University of Singapore , Singapore 117411
- Department of Molecular Cell Biology , Weizmann Institute of Science , Rehovot 76100 , Israel
| | - Jie Yan
- Mechanobiology Institute, National University of Singapore , Singapore 117411
- Department of Physics , National University of Singapore , Singapore 117542
- Centre for Bioimaging Sciences , National University of Singapore , Singapore 117546
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43
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Scherer AN, Anand NS, Koleske AJ. Cortactin stabilization of actin requires actin-binding repeats and linker, is disrupted by specific substitutions, and is independent of nucleotide state. J Biol Chem 2018; 293:13022-13032. [PMID: 29929984 DOI: 10.1074/jbc.ra118.004068] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 06/13/2018] [Indexed: 11/06/2022] Open
Abstract
The actin-binding protein cortactin promotes the formation and maintenance of actin-rich structures, including lamellipodial protrusions in fibroblasts and neuronal dendritic spines. Cortactin cellular functions have been attributed to its activation of the Arp2/3 complex, which stimulates actin branch nucleation, and to its recruitment of Rho family GTPase regulators. Cortactin also binds actin filaments and significantly slows filament depolymerization, but the mechanism by which it does so and the relationship between actin binding and stabilization are unclear. Here we elucidated the cortactin regions that are necessary and sufficient for actin filament binding and stabilization. Using actin cosedimentation assays, we found that the cortactin repeat region binds actin but that the adjacent linker region is required for binding with the same affinity as full-length cortactin. Using total internal reflection fluorescence microscopy to measure the rates of single filament actin depolymerization, we observed that cortactin-actin interactions are sufficient to stabilize actin filaments. Moreover, conserved charged residues in repeat 4 were necessary for high-affinity actin binding, and substitution of these residues significantly impaired cortactin-mediated actin stabilization. Cortactin bound actin with higher affinity than did its paralog, hematopoietic cell-specific Lyn substrate 1 (HS1), and the effects on actin stability were specific to cortactin. Finally, cortactin stabilized ADP-actin filaments, indicating that the stabilization mechanism does not depend on the actin nucleotide state. Together, these results indicate that cortactin binding to actin is necessary and sufficient to stabilize filaments in a concentration-dependent manner, specific to conserved residues in the cortactin repeats, and independent of the actin nucleotide state.
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Affiliation(s)
| | | | - Anthony J Koleske
- Molecular Biophysics and Biochemistry, and .,Neuroscience, Yale University, New Haven, Connecticut 06520
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44
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Structural transitions of F-actin upon ATP hydrolysis at near-atomic resolution revealed by cryo-EM. Nat Struct Mol Biol 2018; 25:528-537. [PMID: 29867215 DOI: 10.1038/s41594-018-0074-0] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 05/02/2018] [Indexed: 11/08/2022]
Abstract
The function of actin is coupled to the nucleotide bound to its active site. ATP hydrolysis is activated during polymerization; a delay between hydrolysis and inorganic phosphate (Pi) release results in a gradient of ATP, ADP-Pi and ADP along actin filaments (F-actin). Actin-binding proteins can recognize F-actin's nucleotide state, using it as a local 'age' tag. The underlying mechanism is complex and poorly understood. Here we report six high-resolution cryo-EM structures of F-actin from rabbit skeletal muscle in different nucleotide states. The structures reveal that actin polymerization repositions the proposed catalytic base, His161, closer to the γ-phosphate. Nucleotide hydrolysis and Pi release modulate the conformational ensemble at the periphery of the filament, thus resulting in open and closed states, which can be sensed by coronin-1B. The drug-like toxin jasplakinolide locks F-actin in an open state. Our results demonstrate in detail how ATP hydrolysis links to F-actin's conformational dynamics and protein interaction.
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45
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Frantzi M, Klimou Z, Makridakis M, Zoidakis J, Latosinska A, Borràs DM, Janssen B, Giannopoulou I, Lygirou V, Lazaris AC, Anagnou NP, Mischak H, Roubelakis MG, Vlahou A. Silencing of Profilin-1 suppresses cell adhesion and tumor growth via predicted alterations in integrin and Ca2+ signaling in T24M-based bladder cancer models. Oncotarget 2018; 7:70750-70768. [PMID: 27683119 PMCID: PMC5342587 DOI: 10.18632/oncotarget.12218] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 09/13/2016] [Indexed: 12/14/2022] Open
Abstract
Bladder cancer (BC) is the second most common malignancy of the genitourinary system, characterized by the highest recurrence rate of all cancers. Treatment options are limited; thus a thorough understanding of the underlying molecular mechanisms is needed to guide the discovery of novel therapeutic targets. Profilins are actin binding proteins with attributed pleiotropic functions to cytoskeletal remodeling, cell adhesion, motility, even transcriptional regulation, not fully characterized yet. Earlier studies from our laboratory revealed that decreased tissue levels of Profilin-1 (PFN1) are correlated with BC progression to muscle invasive disease. Herein, we describe a comprehensive analysis of PFN1 silencing via shRNA, in vitro (by employing T24M cells) and in vivo [(with T24M xenografts in non-obese diabetic severe combined immunodeficient mice (NOD/SCID) mice]. A combination of phenotypic and molecular assays, including migration, proliferation, adhesion assays, flow cytometry and total mRNA sequencing, as well as immunohistochemistry for investigation of selected findings in human specimens were applied. A decrease in BC cell adhesion and tumor growth in vivo following PFN downregulation are observed, likely associated with the concomitant downregulation of Fibronectin receptor, Endothelin-1, and Actin polymerization. A decrease in the levels of multiple key members of the non-canonical Wnt/Ca2+ signaling pathway is also detected following PFN1 suppression, providing the groundwork for future studies, addressing the specific role of PFN1 in Ca2+ signaling, particularly in the muscle invasive disease.
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Affiliation(s)
- Maria Frantzi
- Proteomics Laboratory, Biotechnology Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.,Research and Development Department, Mosaiques Diagnostics GmbH, Hannover, Germany
| | - Zoi Klimou
- Laboratory of Biology, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.,Cell and Gene Therapy Laboratory, Biomedical Research Foundation of The Academy of Athens, Athens, Greece
| | - Manousos Makridakis
- Proteomics Laboratory, Biotechnology Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Jerome Zoidakis
- Proteomics Laboratory, Biotechnology Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Agnieszka Latosinska
- Proteomics Laboratory, Biotechnology Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Daniel M Borràs
- Research and Development Department, GenomeScan B.V., Leiden, The Netherlands
| | - Bart Janssen
- Research and Development Department, GenomeScan B.V., Leiden, The Netherlands
| | - Ioanna Giannopoulou
- First Department of Pathology, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Vasiliki Lygirou
- Proteomics Laboratory, Biotechnology Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Andreas C Lazaris
- First Department of Pathology, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Nicholas P Anagnou
- Laboratory of Biology, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.,Cell and Gene Therapy Laboratory, Biomedical Research Foundation of The Academy of Athens, Athens, Greece
| | - Harald Mischak
- Research and Development Department, Mosaiques Diagnostics GmbH, Hannover, Germany
| | - Maria G Roubelakis
- Laboratory of Biology, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.,Cell and Gene Therapy Laboratory, Biomedical Research Foundation of The Academy of Athens, Athens, Greece
| | - Antonia Vlahou
- Proteomics Laboratory, Biotechnology Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
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46
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mDia1 senses both force and torque during F-actin filament polymerization. Nat Commun 2017; 8:1650. [PMID: 29162803 PMCID: PMC5698482 DOI: 10.1038/s41467-017-01745-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 10/12/2017] [Indexed: 11/08/2022] Open
Abstract
Formins, an important family of force-bearing actin-polymerizing factors, function as homodimers that bind with the barbed end of actin filaments through a ring-like structure assembled from dimerized FH2 domains. It has been hypothesized that force applied to formin may facilitate transition of the FH2 ring from an inhibitory closed conformation to a permissive open conformation, speeding up actin polymerization. We confirm this hypothesis for mDia1 dependent actin polymerization by stretching a single-actin filament in the absence of profilin using magnetic tweezers, and observe that increasing force from 0.5 to 10 pN can drastically speed up the actin polymerization rate. Further, we find that this force-promoted actin polymerization requires torsionally unconstrained actin filament, suggesting that mDia1 also senses torque. As actin filaments are subject to complex mechanical constraints in living cells, these results provide important insights into how formin senses these mechanical constraints and regulates actin organization accordingly.
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47
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Schoppmeyer R, Zhao R, Cheng H, Hamed M, Liu C, Zhou X, Schwarz EC, Zhou Y, Knörck A, Schwär G, Ji S, Liu L, Long J, Helms V, Hoth M, Yu X, Qu B. Human profilin 1 is a negative regulator of CTL mediated cell-killing and migration. Eur J Immunol 2017; 47:1562-1572. [PMID: 28688208 DOI: 10.1002/eji.201747124] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 05/12/2017] [Accepted: 07/05/2017] [Indexed: 12/30/2022]
Abstract
The actin-binding protein profilin1 (PFN1) plays a central role in actin dynamics, which is essential for cytotoxic T lymphocyte (CTL) functions. The functional role of PFN1 in CTLs, however still remains elusive. Here, we identify PFN1 as the only member of the profilin family expressed in primary human CD8+ T cells. Using in vitro assays, we find that PFN1 is a negative regulator of CTL-mediated elimination of target cells. Furthermore, PFN1 is involved in activation-induced lytic granule (LG) release, CTL migration and modulation of actin structures at the immunological synapse (IS). During CTL migration, PFN1 modulates the velocity, protrusion formation patterns and protrusion sustainability. In contrast, PFN1 does not significantly affect migration persistence and the rates of protrusion emergence and retraction. Under in vitro conditions mimicking a tumor microenvironment, we show that PFN1 downregulation promotes CTL invasion into a 3D matrix, without affecting the viability of CTLs in a hydrogen peroxide-enriched microenvironment. Highlighting its potential relevance in cancer, we find that in pancreatic cancer patients, PFN1 expression is substantially decreased in peripheral CD8+ T cells. Taken together, we conclude that PFN1 is a negative regulator for CTL-mediated cytotoxicity and may have an impact on CTL functionality in a tumor-related context.
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Affiliation(s)
- Rouven Schoppmeyer
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Renping Zhao
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - He Cheng
- Department of Pancreatic and Hepatobiliary Surgery, Fudan University Shanghai Cancer Center, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, P.R. China.,Pancreatic Cancer Institute, Fudan University, Shanghai, P.R. China
| | - Mohamed Hamed
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany.,Institute for Biostatistics and Informatics in Medicine and Ageing Research, Rostock University Medical Centre, Rostock, Germany
| | - Chen Liu
- Department of Pancreatic and Hepatobiliary Surgery, Fudan University Shanghai Cancer Center, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, P.R. China.,Pancreatic Cancer Institute, Fudan University, Shanghai, P.R. China
| | - Xiao Zhou
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Eva C Schwarz
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Yan Zhou
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Arne Knörck
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Gertrud Schwär
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Shunrong Ji
- Department of Pancreatic and Hepatobiliary Surgery, Fudan University Shanghai Cancer Center, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, P.R. China.,Pancreatic Cancer Institute, Fudan University, Shanghai, P.R. China
| | - Liang Liu
- Department of Pancreatic and Hepatobiliary Surgery, Fudan University Shanghai Cancer Center, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, P.R. China.,Pancreatic Cancer Institute, Fudan University, Shanghai, P.R. China
| | - Jiang Long
- Department of Pancreatic and Hepatobiliary Surgery, Fudan University Shanghai Cancer Center, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, P.R. China.,Pancreatic Cancer Institute, Fudan University, Shanghai, P.R. China
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Markus Hoth
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Xianjun Yu
- Department of Pancreatic and Hepatobiliary Surgery, Fudan University Shanghai Cancer Center, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, P.R. China.,Pancreatic Cancer Institute, Fudan University, Shanghai, P.R. China
| | - Bin Qu
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
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48
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Sun T, Li S, Ren H. OsFH15, a class I formin, interacts with microfilaments and microtubules to regulate grain size via affecting cell expansion in rice. Sci Rep 2017; 7:6538. [PMID: 28747699 PMCID: PMC5529588 DOI: 10.1038/s41598-017-06431-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 06/13/2017] [Indexed: 11/23/2022] Open
Abstract
Grain size is an important agronomic trait determining rice yield and is mainly restricted by spikelet hull size. However, it remains largely unknown how the spikelet hull size is regulated. In this study, OsFH15, a class I formin protein in Oryza sativa, was found to be able to regulate the size of cells and spikelet hull. OsFH15-Cas9 and OsFH15-RNAi mutants had decreased grain size with reduced cell length, cell width and cell area of inner epidermal cells of the lemma compared with wild-type plants. By contrast, OsFH15-overexpressed plants had increased grain size with larger cells, as well as more abundant microtubules (MTs) and actin filaments (AFs) arrays. OsFH15 was mainly expressed in shoot apical meristem (SAM), spikelets, spikelet hulls and seeds in rice. In vitro biochemical experiments showed that OsFH15 can efficiently nucleate actin polymerization with or without profilin, can cap the barbed end of AFs, and can bind and bundle both AFs and MTs. OsFH15 can also crosslink AFs with MTs, and preferentially bind MTs to AFs. These results demonstrated that OsFH15 played an important role in grain-size control by affecting cell expansion through regulating AFs and MTs.
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Affiliation(s)
- Tiantian Sun
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Shanwei Li
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Haiyun Ren
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing, 100875, China.
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49
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STK16 regulates actin dynamics to control Golgi organization and cell cycle. Sci Rep 2017; 7:44607. [PMID: 28294156 PMCID: PMC5353726 DOI: 10.1038/srep44607] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/09/2017] [Indexed: 11/30/2022] Open
Abstract
STK16 is a ubiquitously expressed, myristoylated, and palmitoylated serine/threonine protein kinase with underexplored functions. Recently, it was shown to be involved in cell division but the mechanism remains unclear. Here we found that human STK16 localizes to the Golgi complex throughout the cell cycle and plays important roles in Golgi structure regulation. STK16 knockdown or kinase inhibition disrupts actin polymers and causes fragmented Golgi in cells. In vitro assays show that STK16 directly binds to actin and regulates actin dynamics in a concentration- and kinase activity-dependent way. In addition, STK16 knockdown or kinase inhibition not only delays mitotic entry and prolongs mitosis, but also causes prometaphase and cytokinesis arrest. Therefore, we revealed STK16 as a novel actin binding protein that resides in the Golgi, which regulates actin dynamics to control Golgi structure and participate in cell cycle progression.
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50
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Shekhar S, Carlier MF. Single-filament kinetic studies provide novel insights into regulation of actin-based motility. Mol Biol Cell 2016; 27:1-6. [PMID: 26715420 PMCID: PMC4694749 DOI: 10.1091/mbc.e15-06-0352] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Polarized assembly of actin filaments forms the basis of actin-based motility and is regulated both spatially and temporally. Cells use a variety of mechanisms by which intrinsically slower processes are accelerated, and faster ones decelerated, to match rates observed in vivo. Here we discuss how kinetic studies of individual reactions and cycles that drive actin remodeling have provided a mechanistic and quantitative understanding of such processes. We specifically consider key barbed-end regulators such as capping protein and formins as illustrative examples. We compare and contrast different kinetic approaches, such as the traditional pyrene-polymerization bulk assays, as well as more recently developed single-filament and single-molecule imaging approaches. Recent development of novel biophysical methods for sensing and applying forces will in future allow us to address the very important relationship between mechanical stimulus and kinetics of actin-based motility.
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Affiliation(s)
- Shashank Shekhar
- Cytoskeleton Dynamics and Cell Motility, Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette, France
| | - Marie-France Carlier
- Cytoskeleton Dynamics and Cell Motility, Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette, France
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