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Johnson AN. Myotube Guidance: Shaping up the Musculoskeletal System. J Dev Biol 2024; 12:25. [PMID: 39311120 PMCID: PMC11417883 DOI: 10.3390/jdb12030025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 07/20/2024] [Accepted: 09/12/2024] [Indexed: 09/26/2024] Open
Abstract
Myofibers are highly specialized contractile cells of skeletal muscles, and dysregulation of myofiber morphogenesis is emerging as a contributing cause of myopathies and structural birth defects. Myotubes are the myofiber precursors and undergo a dramatic morphological transition into long bipolar myofibers that are attached to tendons on two ends. Similar to axon growth cones, myotube leading edges navigate toward target cells and form cell-cell connections. The process of myotube guidance connects myotubes with the correct tendons, orients myofiber morphology with the overall body plan, and generates a functional musculoskeletal system. Navigational signaling, addition of mass and volume, and identification of target cells are common events in myotube guidance and axon guidance, but surprisingly, the mechanisms regulating these events are not completely overlapping in myotubes and axons. This review summarizes the strategies that have evolved to direct myotube leading edges to predetermined tendon cells and highlights key differences between myotube guidance and axon guidance. The association of myotube guidance pathways with developmental disorders is also discussed.
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Affiliation(s)
- Aaron N Johnson
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
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2
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Srivastava P, Rai A, Kumar M. Expression profile of diagnostic genes in oral submucous fibrosis. Pathol Res Pract 2024; 260:155416. [PMID: 38944023 DOI: 10.1016/j.prp.2024.155416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 06/09/2024] [Accepted: 06/19/2024] [Indexed: 07/01/2024]
Abstract
Oral Submucous Fibrosis (OSMF) is a chronic precancerous disorder of the oral mucosa caused by chewing of areca nut and its other variants. Chewing of areca nuts leads to dysregulated expression of specific genes, leading to various premalignant or malignant disorders. This study aimed to determine the differential expression of the diagnostic genes (MYH6, TNNT3, MYL1, and TPM2) in healthy controls and OSMF patients using saliva and tissue samples, determining the histopathological grade of the clinical samples. A total of 20 patients were included in the study and were divided into two groups: Group I consisted of 10 healthy patients (control group) and Group II consisted of 10 OSMF patients. Unstimulated whole saliva samples were collected from both groups, and the tissue samples were divided into two parts: one for RT-qPCR analysis and the other for histopathological assay. The expression profile of genes concerning OSMF saliva and tissue samples was significantly upregulated compared to the healthy control, and all the clinical samples of the study were categorized into histopathological grade 1. The findings of this study concluded that these genes can be referred to as diagnostic genes for OSMF in early and very early clinical samples, and saliva can be used as a promising diagnostic tool for early OSMF studies.
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Affiliation(s)
- Prerna Srivastava
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, India
| | - Arpita Rai
- Dental Institute, Rajendra Institute of Medical Sciences, Ranchi 834009, India
| | - Manish Kumar
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, India.
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3
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Pollard LW, Boczkowska M, Dominguez R, Ostap EM. Myosin-1C differentially displaces tropomyosin isoforms altering their inhibition of motility. J Biol Chem 2024; 300:107539. [PMID: 38971309 PMCID: PMC11338116 DOI: 10.1016/j.jbc.2024.107539] [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: 05/15/2024] [Revised: 06/25/2024] [Accepted: 06/27/2024] [Indexed: 07/08/2024] Open
Abstract
Force generation and motility by actomyosin in nonmuscle cells are spatially regulated by ∼40 tropomyosin (Tpm) isoforms. The means by which Tpms are targeted to specific cellular regions and the mechanisms that result in differential activity of myosin paralogs are unknown. We show that Tpm3.1 and Tpm1.7 inhibit Myosin-IC (Myo1C), with Tpm1.7 more effectively reducing the number of gliding filaments than Tpm3.1. Strikingly, cosedimentation and fluorescence microscopy assays revealed that Tpm3.1 is displaced from actin by Myo1C and not by myosin-II. In contrast, Tpm1.7 is only weakly displaced by Myo1C. Unlike other characterized myosins, Myo1C motility is inhibited by Tpm when the Tpm-actin filament is activated by myosin-II. These results point to a mechanism for the exclusion of myosin-I paralogs from cellular Tpm-decorated actin filaments that are activated by other myosins. Additionally, our results suggest a potential mechanism for myosin-induced Tpm sorting in cells.
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Affiliation(s)
- Luther W Pollard
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
| | - Malgorzata Boczkowska
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Roberto Dominguez
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - E Michael Ostap
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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4
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Lapshina KK, Nefedova VV, Nabiev SR, Roman SG, Shchepkin DV, Kopylova GV, Kochurova AM, Beldiia EA, Kleymenov SY, Levitsky DI, Matyushenko AM. Functional and Structural Properties of Cytoplasmic Tropomyosin Isoforms Tpm1.8 and Tpm1.9. Int J Mol Sci 2024; 25:6873. [PMID: 38999987 PMCID: PMC11240984 DOI: 10.3390/ijms25136873] [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: 05/14/2024] [Revised: 06/11/2024] [Accepted: 06/19/2024] [Indexed: 07/14/2024] Open
Abstract
The actin cytoskeleton is one of the most important players in cell motility, adhesion, division, and functioning. The regulation of specific microfilament formation largely determines cellular functions. The main actin-binding protein in animal cells is tropomyosin (Tpm). The unique structural and functional diversity of microfilaments is achieved through the diversity of Tpm isoforms. In our work, we studied the properties of the cytoplasmic isoforms Tpm1.8 and Tpm1.9. The results showed that these isoforms are highly thermostable and differ in the stability of their central and C-terminal fragments. The properties of these isoforms were largely determined by the 6th exons. Thus, the strength of the end-to-end interactions, as well as the affinity of the Tpm molecule for F-actin, differed between the Tpm1.8 and Tpm1.9 isoforms. They were determined by whether an alternative internal exon, 6a or 6b, was included in the Tpm isoform structure. The strong interactions of the Tpm1.8 and Tpm1.9 isoforms with F-actin led to the formation of rigid actin filaments, the stiffness of which was measured using an optical trap. It is quite possible that the structural and functional features of the Tpm isoforms largely determine the appearance of these isoforms in the rigid actin structures of the cell cortex.
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Affiliation(s)
- Ksenia K. Lapshina
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (K.K.L.); (V.V.N.); (S.G.R.); (S.Y.K.); (D.I.L.)
- Department of Biophysics, Faculty of Physics, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Victoria V. Nefedova
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (K.K.L.); (V.V.N.); (S.G.R.); (S.Y.K.); (D.I.L.)
| | - Salavat R. Nabiev
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049 Yekaterinburg, Russia; (S.R.N.); (D.V.S.); (G.V.K.); (A.M.K.); (E.A.B.)
| | - Svetlana G. Roman
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (K.K.L.); (V.V.N.); (S.G.R.); (S.Y.K.); (D.I.L.)
| | - Daniil V. Shchepkin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049 Yekaterinburg, Russia; (S.R.N.); (D.V.S.); (G.V.K.); (A.M.K.); (E.A.B.)
| | - Galina V. Kopylova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049 Yekaterinburg, Russia; (S.R.N.); (D.V.S.); (G.V.K.); (A.M.K.); (E.A.B.)
| | - Anastasia M. Kochurova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049 Yekaterinburg, Russia; (S.R.N.); (D.V.S.); (G.V.K.); (A.M.K.); (E.A.B.)
| | - Evgenia A. Beldiia
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049 Yekaterinburg, Russia; (S.R.N.); (D.V.S.); (G.V.K.); (A.M.K.); (E.A.B.)
| | - Sergey Y. Kleymenov
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (K.K.L.); (V.V.N.); (S.G.R.); (S.Y.K.); (D.I.L.)
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Dmitrii I. Levitsky
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (K.K.L.); (V.V.N.); (S.G.R.); (S.Y.K.); (D.I.L.)
| | - Alexander M. Matyushenko
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (K.K.L.); (V.V.N.); (S.G.R.); (S.Y.K.); (D.I.L.)
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5
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Cagigas ML, Ariotti N, Hook J, Rae J, Parton RG, Bryce NS, Gunning PW, Hardeman EC. Single molecule visualization of tropomyosin isoform organization in the mammalian actin cytoskeleton. Cytoskeleton (Hoboken) 2024. [PMID: 38872463 DOI: 10.1002/cm.21883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 04/22/2024] [Accepted: 05/29/2024] [Indexed: 06/15/2024]
Abstract
The actin cytoskeleton is composed of both branched and unbranched actin filaments. In mammals, the unbranched actin filaments are primarily copolymers of actin and tropomyosin. Biochemical and imaging studies indicate that different tropomyosin isoforms are segregated to different actin filament populations in cells and tissues, providing isoform-specific functionality to the actin filament. Intrinsic to this model is the prediction that single-molecule imaging of tropomyosin isoforms would confirm homopolymer formation along the length of single actin filaments, a knowledge gap that remains unaddressed in the cellular environment. We combined chemical labeling of genetically engineered tropomyosin isoforms with electron tomography to locate individual tropomyosin molecules in fibroblasts. We find that the organization of two non-muscle tropomyosins, Tpm3.1 with Tpm4.2, can be distinguished from each other using light and electron microscopy. Visualization of single tropomyosin molecules associated with actin filaments supports the hypothesis that tropomyosins form continuous homopolymers, instead of heteropolymers, in the presence of all physiologically native actin-binding proteins. This is true for both isoforms tested. Furthermore, the data suggest that the tropomyosin molecules on one side of an actin filament may not be in register with those on the opposite side, indicating that each tropomyosin polymer may assembly independently.
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Affiliation(s)
- Maria L Cagigas
- School of Biomedical Sciences, UNSW Sydney, Sydney, Australia
| | - Nicholas Ariotti
- School of Biomedical Sciences, UNSW Sydney, Sydney, Australia
- Electron Microscope Unit, UNSW, Sydney, Australia
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Jeff Hook
- School of Biomedical Sciences, UNSW Sydney, Sydney, Australia
| | - James Rae
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Robert G Parton
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Australia
| | - Nicole S Bryce
- School of Biomedical Sciences, UNSW Sydney, Sydney, Australia
| | - Peter W Gunning
- School of Biomedical Sciences, UNSW Sydney, Sydney, Australia
| | - Edna C Hardeman
- School of Biomedical Sciences, UNSW Sydney, Sydney, Australia
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6
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Ceron RH, Báez-Cruz FA, Palmer NJ, Carman PJ, Boczkowska M, Heuckeroth RO, Ostap EM, Dominguez R. Molecular mechanisms linking missense ACTG2 mutations to visceral myopathy. SCIENCE ADVANCES 2024; 10:eadn6615. [PMID: 38820162 PMCID: PMC11141634 DOI: 10.1126/sciadv.adn6615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 04/29/2024] [Indexed: 06/02/2024]
Abstract
Visceral myopathy is a life-threatening disease characterized by muscle weakness in the bowel, bladder, and uterus. Mutations in smooth muscle γ-actin (ACTG2) are the most common cause of the disease, but the mechanisms by which the mutations alter muscle function are unknown. Here, we examined four prevalent ACTG2 mutations (R40C, R148C, R178C, and R257C) that cause different disease severity and are spread throughout the actin fold. R178C displayed premature degradation, R148C disrupted interactions with actin-binding proteins, R40C inhibited polymerization, and R257C destabilized filaments. Because these mutations are heterozygous, we also analyzed 50/50 mixtures with wild-type (WT) ACTG2. The WT/R40C mixture impaired filament nucleation by leiomodin 1, and WT/R257C produced filaments that were easily fragmented by smooth muscle myosin. Smooth muscle tropomyosin isoform Tpm1.4 partially rescued the defects of R40C and R257C. Cryo-electron microscopy structures of filaments formed by R40C and R257C revealed disrupted intersubunit contacts. The biochemical and structural properties of the mutants correlate with their genotype-specific disease severity.
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Affiliation(s)
- Rachel H. Ceron
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- The Children’s Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Faviolla A. Báez-Cruz
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nicholas J. Palmer
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Peter J. Carman
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Malgorzata Boczkowska
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Robert O. Heuckeroth
- The Children’s Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - E. Michael Ostap
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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7
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Abdul Manap AS, Wisham AA, Wong FW, Ahmad Najmi HR, Ng ZF, Diba RS. Mapping the function of MicroRNAs as a critical regulator of tumor-immune cell communication in breast cancer and potential treatment strategies. Front Cell Dev Biol 2024; 12:1390704. [PMID: 38726321 PMCID: PMC11079208 DOI: 10.3389/fcell.2024.1390704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 04/09/2024] [Indexed: 05/12/2024] Open
Abstract
Among women, breast cancer ranks as the most prevalent form of cancer, and the presence of metastases significantly reduces prognosis and diminishes overall survival rates. Gaining insights into the biological mechanisms governing the conversion of cancer cells, their subsequent spread to other areas of the body, and the immune system's monitoring of tumor growth will contribute to the advancement of more efficient and targeted therapies. MicroRNAs (miRNAs) play a critical role in the interaction between tumor cells and immune cells, facilitating tumor cells' evasion of the immune system and promoting cancer progression. Additionally, miRNAs also influence metastasis formation, including the establishment of metastatic sites and the transformation of tumor cells into migratory phenotypes. Specifically, dysregulated expression of these genes has been associated with abnormal expression of oncogenes and tumor suppressor genes, thereby facilitating tumor development. This study aims to provide a concise overview of the significance and function of miRNAs in breast cancer, focusing on their involvement as tumor suppressors in the antitumor immune response and as oncogenes in metastasis formation. Furthermore, miRNAs hold tremendous potential as targets for gene therapy due to their ability to modulate specific pathways that can either promote or suppress carcinogenesis. This perspective highlights the latest strategies developed for miRNA-based therapies.
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Affiliation(s)
- Aimi Syamima Abdul Manap
- Department of Biomedical Science, College of Veterinary Medicine, King Faisal University, Al-Ahsa, Saudi Arabia
| | | | - Fei Wen Wong
- Faculty of Biosciences, MAHSA University, Kuala Langat, Selangor, Malaysia
| | | | - Zhi Fei Ng
- Faculty of Biosciences, MAHSA University, Kuala Langat, Selangor, Malaysia
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8
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Xu T, Verhagen MP, Teeuwssen M, Sun W, Joosten R, Sacchetti A, Ewing-Graham PC, Jansen MPHM, Boere IA, Bryce NS, Zeng J, Treutlein HR, Hook J, Hardeman EC, Gunning PW, Fodde R. Tropomyosin1 isoforms underlie epithelial to mesenchymal plasticity, metastatic dissemination, and resistance to chemotherapy in high-grade serous ovarian cancer. Cell Death Differ 2024; 31:360-377. [PMID: 38365970 PMCID: PMC10923901 DOI: 10.1038/s41418-024-01267-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 02/01/2024] [Accepted: 02/06/2024] [Indexed: 02/18/2024] Open
Abstract
Phenotypic plasticity, defined as the ability of individual cells with stable genotypes to exert different phenotypes upon exposure to specific environmental cues, represent the quintessential hallmark of the cancer cell en route from the primary lesion to distant organ sites where metastatic colonization will occur. Phenotypic plasticity is driven by a broad spectrum of epigenetic mechanisms that allow for the reversibility of epithelial-to-mesenchymal and mesenchymal-to-epithelial transitions (EMT/MET). By taking advantage of the co-existence of epithelial and quasi-mesenchymal cells within immortalized cancer cell lines, we have analyzed the role of EMT-related gene isoforms in the regulation of epithelial mesenchymal plasticity (EMP) in high grade serous ovarian cancer. When compared with colon cancer, a distinct spectrum of downstream targets characterizes quasi-mesenchymal ovarian cancer cells, likely to reflect the different modalities of metastasis formation between these two types of malignancy, i.e. hematogenous in colon and transcoelomic in ovarian cancer. Moreover, upstream RNA-binding proteins differentially expressed between epithelial and quasi-mesenchymal subpopulations of ovarian cancer cells were identified that underlie differential regulation of EMT-related isoforms. In particular, the up- and down-regulation of RBM24 and ESRP1, respectively, represent a main regulator of EMT in ovarian cancer cells. To validate the functional and clinical relevance of our approach, we selected and functionally analyzed the Tropomyosin 1 gene (TPM1), encoding for a protein that specifies the functional characteristics of individual actin filaments in contractile cells, among the ovarian-specific downstream AS targets. The low-molecular weight Tpm1.8/9 isoforms are specifically expressed in patient-derived ascites and promote invasion through activation of EMT and Wnt signaling, together with a broad spectrum of inflammation-related pathways. Moreover, Tpm1.8/9 expression confers resistance to taxane- and platinum-based chemotherapy. Small molecule inhibitors that target the Tpm1 isoforms support targeting Tpm1.8/9 as therapeutic targets for the development of future tailor-made clinical interventions.
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Affiliation(s)
- Tong Xu
- Department of Pathology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Mathijs P Verhagen
- Department of Pathology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Miriam Teeuwssen
- Department of Pathology, Erasmus University Medical Center, Rotterdam, The Netherlands
- Elisabeth-TweeSteden Ziekenhuis (ETZ), Tilburg, The Netherlands
| | - Wenjie Sun
- Institut Curie, Laboratory of Genetics and Developmental Biology, Paris, France
| | - Rosalie Joosten
- Department of Pathology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Andrea Sacchetti
- Department of Pathology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | | | - Maurice P H M Jansen
- Department of Medical Oncology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ingrid A Boere
- Department of Medical Oncology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Nicole S Bryce
- School of Biomedical Sciences, Faculty of Medicine and Health, The University of New South Wales, Sydney, New South Wales, Australia
- The Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Jun Zeng
- Computist Bio-NanoTech, Scoresby, VIC, 3179, Australia
| | - Herbert R Treutlein
- Computist Bio-NanoTech, Scoresby, VIC, 3179, Australia
- Sanoosa Pty. Ltd, Moonee Ponds, VIC, 3039, Australia
| | - Jeff Hook
- School of Biomedical Sciences, Faculty of Medicine and Health, The University of New South Wales, Sydney, New South Wales, Australia
| | - Edna C Hardeman
- School of Biomedical Sciences, Faculty of Medicine and Health, The University of New South Wales, Sydney, New South Wales, Australia
| | - Peter W Gunning
- School of Biomedical Sciences, Faculty of Medicine and Health, The University of New South Wales, Sydney, New South Wales, Australia
| | - Riccardo Fodde
- Department of Pathology, Erasmus University Medical Center, Rotterdam, The Netherlands.
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9
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Martin JL, Khan A, Grintsevich EE. Actin Isoform Composition and Binding Factors Fine-Tune Regulatory Impact of Mical Enzymes. Int J Mol Sci 2023; 24:16651. [PMID: 38068973 PMCID: PMC10705957 DOI: 10.3390/ijms242316651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/20/2023] [Accepted: 11/20/2023] [Indexed: 12/18/2023] Open
Abstract
Mical family enzymes are unusual actin regulators that prime filaments (F-actin) for disassembly via the site-specific oxidation of M44/M47. Filamentous actin acts as a substrate of Mical enzymes, as well as an activator of their NADPH oxidase activity, which leads to hydrogen peroxide generation. Mical enzymes are required for cytokinesis, muscle and heart development, dendritic pruning, and axonal guidance, among other processes. Thus, it is critical to understand how this family of actin regulators functions in different cell types. Vertebrates express six actin isoforms in a cell-specific manner, but MICALs' impact on their intrinsic properties has never been systematically investigated. Our data reveal the differences in the intrinsic dynamics of Mical-oxidized actin isoforms. Furthermore, our results connect the intrinsic dynamics of actin isoforms and their redox state with the patterns of hydrogen peroxide (H2O2) generation by MICALs. We documented that the differential properties of actin isoforms translate into the distinct patterns of hydrogen peroxide generation in Mical/NADPH-containing systems. Moreover, our results establish a conceptual link between actin stabilization by interacting factors and its ability to activate MICALs' NADPH oxidase activity. Altogether, our results suggest that the regulatory impact of MICALs may differ depending on the isoform-related identities of local actin networks.
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Affiliation(s)
| | | | - Elena E. Grintsevich
- Department of Chemistry and Biochemistry, California State University, Long Beach (CSULB), Long Beach, CA 90840, USA
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10
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Ono S, Watabe E, Morisaki K, Ono K, Kuroyanagi H. Alternative splicing of a single exon causes a major impact on the affinity of Caenorhabditis elegans tropomyosin isoforms for actin filaments. Front Cell Dev Biol 2023; 11:1208913. [PMID: 37745299 PMCID: PMC10512467 DOI: 10.3389/fcell.2023.1208913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 08/29/2023] [Indexed: 09/26/2023] Open
Abstract
Tropomyosin is generally known as an actin-binding protein that regulates actomyosin interaction and actin filament stability. In metazoans, multiple tropomyosin isoforms are expressed, and some of them are involved in generating subpopulations of actin cytoskeleton in an isoform-specific manner. However, functions of many tropomyosin isoforms remain unknown. Here, we report identification of a novel alternative exon in the Caenorhabditis elegans tropomyosin gene and characterization of the effects of alternative splicing on the properties of tropomyosin isoforms. Previous studies have reported six tropomyosin isoforms encoded by the C. elegans lev-11 tropomyosin gene. We identified a seventh isoform, LEV-11U, that contained a novel alternative exon, exon 7c (E7c). LEV-11U is a low-molecular-weight tropomyosin isoform that differs from LEV-11T only at the exon 7-encoded region. In silico analyses indicated that the E7c-encoded peptide sequence was unfavorable for coiled-coil formation and distinct from other tropomyosin isoforms in the pattern of electrostatic surface potentials. In vitro, LEV-11U bound poorly to actin filaments, whereas LEV-11T bound to actin filaments in a saturable manner. When these isoforms were transgenically expressed in the C. elegans striated muscle, LEV-11U was present in the diffuse cytoplasm with tendency to form aggregates, whereas LEV-11T co-localized with sarcomeric actin filaments. Worms with a mutation in E7c showed reduced motility and brood size, suggesting that this exon is important for the optimal health. These results indicate that alternative splicing of a single exon can produce biochemically diverged tropomyosin isoforms and suggest that a tropomyosin isoform with poor actin affinity has a novel biological function.
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Affiliation(s)
- Shoichiro Ono
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
- Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, United States
| | - Eichi Watabe
- Laboratory of Gene Expression, Graduate School of Biomedical Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Keita Morisaki
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Kanako Ono
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
- Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, United States
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Graduate School of Biomedical Sciences, Tokyo Medical and Dental University, Tokyo, Japan
- Department of Biochemistry, University of the Ryukyus Graduate School of Medicine, Okinawa, Japan
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11
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Logvinov AS, Nefedova VV, Yampolskaya DS, Kleymenov SY, Levitsky DI, Matyushenko AM. Structural and Functional Properties of Tropomyosin Isoforms Tpm4.1 and Tpm2.1. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:801-809. [PMID: 37748876 DOI: 10.1134/s0006297923060081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 05/05/2023] [Accepted: 05/10/2023] [Indexed: 09/27/2023]
Abstract
Tropomyosin (Tpm) is one of the most important partners of actin filament that largely determines its properties. In animal organisms, there are different isoforms of Tpm, which are believed to be involved in the regulation of various cellular functions. However, molecular mechanisms by which various Tpm cytoplasmic regulate of the functioning of actin filaments are still poorly understood. Here, we investigated the properties of Tpm2.1 and Tpm4.1 isoforms and compared them to each other and to more extensively studied Tpm isoforms. Tpm2.1 and Tpm4.1 were very similar in their affinity to F-actin, thermal stability, and resistance to limited proteolysis by trypsin, but differed markedly in the viscosity of their solutions and thermal stability of their complexes with F-actin. The main difference of Tpm2.1 and Tpm4.1 from other Tpm isoforms (e.g., Tpm1.6 and Tpm1.7) was their extremely low thermal stability as measured by the CD and DSC methods. We suggested the possible causes of this instability based on comparing the amino acid sequences of Tpm4.1 and Tpm2.1 with the sequences of Tpm1.6 and Tpm1.7 isoforms, respectively, that have similar exon structure.
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Affiliation(s)
- Andrey S Logvinov
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Victoria V Nefedova
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Daria S Yampolskaya
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Sergey Y Kleymenov
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, 119334, Russia
| | - Dmitrii I Levitsky
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
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12
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Dong S, Zheng W, Pinkerton N, Hansen J, Tikunova SB, Davis JP, Heissler SM, Kudryashova E, Egelman EH, Kudryashov DS. Photorhabdus luminescens TccC3 Toxin Targets the Dynamic Population of F-Actin and Impairs Cell Cortex Integrity. Int J Mol Sci 2022; 23:7026. [PMID: 35806028 PMCID: PMC9266650 DOI: 10.3390/ijms23137026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/17/2022] [Accepted: 06/22/2022] [Indexed: 12/30/2022] Open
Abstract
Due to its essential role in cellular processes, actin is a common target for bacterial toxins. One such toxin, TccC3, is an effector domain of the ABC-toxin produced by entomopathogenic bacteria of Photorhabdus spp. Unlike other actin-targeting toxins, TccC3 uniquely ADP-ribosylates actin at Thr-148, resulting in the formation of actin aggregates and inhibition of phagocytosis. It has been shown that the fully modified F-actin is resistant to depolymerization by cofilin and gelsolin, but their effects on partially modified actin were not explored. We found that only F-actin unprotected by tropomyosin is the physiological TccC3 substrate. Yet, ADP-ribosylated G-actin can be produced upon cofilin-accelerated F-actin depolymerization, which was only mildly inhibited in partially modified actin. The affinity of TccC3-ADP-ribosylated G-actin for profilin and thymosin-β4 was weakened moderately but sufficiently to potentiate spontaneous polymerization in their presence. Interestingly, the Arp2/3-mediated nucleation was also potentiated by T148-ADP-ribosylation. Notably, even partially modified actin showed reduced bundling by plastins and α-actinin. In agreement with the role of these and other tandem calponin-homology domain actin organizers in the assembly of the cortical actin network, TccC3 induced intense membrane blebbing in cultured cells. Overall, our data suggest that TccC3 imposes a complex action on the cytoskeleton by affecting F-actin nucleation, recycling, and interaction with actin-binding proteins involved in the integration of actin filaments with each other and cellular elements.
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Affiliation(s)
- Songyu Dong
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
| | - Weili Zheng
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22903, USA; (W.Z.); (E.H.E.)
| | - Nicholas Pinkerton
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
| | - Jacob Hansen
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
| | - Svetlana B. Tikunova
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA; (S.B.T.); (J.P.D.); (S.M.H.)
| | - Jonathan P. Davis
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA; (S.B.T.); (J.P.D.); (S.M.H.)
| | - Sarah M. Heissler
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA; (S.B.T.); (J.P.D.); (S.M.H.)
| | - Elena Kudryashova
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
| | - Edward H. Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22903, USA; (W.Z.); (E.H.E.)
| | - Dmitri S. Kudryashov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
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13
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McAdow J, Yang S, Ou T, Huang G, Dobbs MB, Gurnett CA, Greenberg MJ, Johnson AN. A pathogenic mechanism associated with myopathies and structural birth defects involves TPM2-directed myogenesis. JCI Insight 2022; 7:152466. [PMID: 35579956 PMCID: PMC9309062 DOI: 10.1172/jci.insight.152466] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 05/13/2022] [Indexed: 11/18/2022] Open
Abstract
Nemaline myopathy (NM) is the most common congenital myopathy, characterized by extreme weakness of the respiratory, limb, and facial muscles. Pathogenic variants in Tropomyosin 2 (TPM2), which encodes a skeletal muscle-specific actin binding protein essential for sarcomere function, cause a spectrum of musculoskeletal disorders that include NM as well as cap myopathy, congenital fiber type disproportion, and distal arthrogryposis (DA). The in vivo pathomechanisms underlying TPM2-related disorders are unknown, so we expressed a series of dominant, pathogenic TPM2 variants in Drosophila embryos and found 4 variants significantly affected muscle development and muscle function. Transient overexpression of the 4 variants also disrupted the morphogenesis of mouse myotubes in vitro and negatively affected zebrafish muscle development in vivo. We used transient overexpression assays in zebrafish to characterize 2 potentially novel TPM2 variants and 1 recurring variant that we identified in patients with DA (V129A, E139K, A155T, respectively) and found these variants caused musculoskeletal defects similar to those of known pathogenic variants. The consistency of musculoskeletal phenotypes in our assays correlated with the severity of clinical phenotypes observed in our patients with DA, suggesting disrupted myogenesis is a potentially novel pathomechanism of TPM2 disorders and that our myogenic assays can predict the clinical severity of TPM2 variants.
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Affiliation(s)
- Jennifer McAdow
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Shuo Yang
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Tiffany Ou
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Gary Huang
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Matthew B Dobbs
- Paley Orthopedic and Spine Institute, West Palm Beach, Florida, USA
| | - Christina A Gurnett
- Department of Neurology.,Department of Orthopedic Surgery.,Department of Pediatrics, and
| | - Michael J Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Aaron N Johnson
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, Missouri, USA
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14
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Bamburg JR, Minamide LS, Wiggan O, Tahtamouni LH, Kuhn TB. Cofilin and Actin Dynamics: Multiple Modes of Regulation and Their Impacts in Neuronal Development and Degeneration. Cells 2021; 10:cells10102726. [PMID: 34685706 PMCID: PMC8534876 DOI: 10.3390/cells10102726] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/06/2021] [Accepted: 10/07/2021] [Indexed: 02/06/2023] Open
Abstract
Proteins of the actin depolymerizing factor (ADF)/cofilin family are ubiquitous among eukaryotes and are essential regulators of actin dynamics and function. Mammalian neurons express cofilin-1 as the major isoform, but ADF and cofilin-2 are also expressed. All isoforms bind preferentially and cooperatively along ADP-subunits in F-actin, affecting the filament helical rotation, and when either alone or when enhanced by other proteins, promotes filament severing and subunit turnover. Although self-regulating cofilin-mediated actin dynamics can drive motility without post-translational regulation, cells utilize many mechanisms to locally control cofilin, including cooperation/competition with other proteins. Newly identified post-translational modifications function with or are independent from the well-established phosphorylation of serine 3 and provide unexplored avenues for isoform specific regulation. Cofilin modulates actin transport and function in the nucleus as well as actin organization associated with mitochondrial fission and mitophagy. Under neuronal stress conditions, cofilin-saturated F-actin fragments can undergo oxidative cross-linking and bundle together to form cofilin-actin rods. Rods form in abundance within neurons around brain ischemic lesions and can be rapidly induced in neurites of most hippocampal and cortical neurons through energy depletion or glutamate-induced excitotoxicity. In ~20% of rodent hippocampal neurons, rods form more slowly in a receptor-mediated process triggered by factors intimately connected to disease-related dementias, e.g., amyloid-β in Alzheimer’s disease. This rod-inducing pathway requires a cellular prion protein, NADPH oxidase, and G-protein coupled receptors, e.g., CXCR4 and CCR5. Here, we will review many aspects of cofilin regulation and its contribution to synaptic loss and pathology of neurodegenerative diseases.
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Affiliation(s)
- James R. Bamburg
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
- Correspondence: ; Tel.: +1-970-988-9120; Fax: +1-970-491-0494
| | - Laurie S. Minamide
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
| | - O’Neil Wiggan
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
| | - Lubna H. Tahtamouni
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
- Department of Biology and Biotechnology, The Hashemite University, Zarqa 13115, Jordan
| | - Thomas B. Kuhn
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA; (L.S.M.); (O.W.); (L.H.T.); (T.B.K.)
- Department of Chemistry and Biochemistry, University of Alaska, Fairbanks, AK 99775, USA
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15
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Cancer type-specific alterations in actin genes: Worth a closer look? INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 360:133-184. [PMID: 33962749 DOI: 10.1016/bs.ircmb.2021.02.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Actins form a strongly conserved family of proteins that are central to the functioning of the actin cytoskeleton partaking in natural processes such as cell division, adhesion, contraction and migration. These processes, however, also occur during the various phases of cancer progression. Yet, surprisingly, alterations in the six human actin genes in cancer studies have received little attention and the focus was mostly on deregulated expression levels of actins and even more so of actin-binding or regulatory proteins. Starting from the early mutation work in the 1980s, we propose based on reviewing literature and data from patient cancer genomes that alterations in actin genes are different in distinct cancer subtypes, suggesting some specificity. These actin gene alterations include (missense) mutations, gene fusions and copy number alterations (deletions and amplifications) and we illustrate their occurrence for a limited number of examples including actin mutations in lymphoid cancers and nonmelanoma skin cancer and actin gene copy number alterations for breast, prostate and liver cancers. A challenge in the future will be to further sort out the specificity per actin gene, alteration type and cancer subtype. Even more challenging is (experimentally) distinguishing between cause and consequence: which alterations are passengers and which are involved in tumor progression of particular cancer subtypes?
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16
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Profiling NSD3-dependent neural crest gene expression reveals known and novel candidate regulatory factors. Dev Biol 2021; 475:118-130. [PMID: 33705737 DOI: 10.1016/j.ydbio.2021.02.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/17/2021] [Accepted: 02/21/2021] [Indexed: 12/17/2022]
Abstract
The lysine methyltransferase NSD3 is required for the expression of key neural crest transcription factors and the migration of neural crest cells. Nevertheless, a complete view of the genes dependent upon NSD3 for expression and the developmental processes impacted by NSD3 in the neural crest was lacking. We used RNA sequencing (RNA-seq) to profile transcripts differentially expressed after NSD3 knockdown in chick premigratory neural crest cells, identifying 674 genes. Gene Ontology and gene set enrichment analyses further support a requirement for NSD3 during neural crest development and show that NSD3 knockdown also upregulates ribosome biogenesis. To validate our results, we selected three genes not previously associated with neural crest development, Astrotactin 1 (Astn1), Dispatched 3 (Disp3), and Tropomyosin 1 (Tpm1). Using whole mount in situ hybridization, we show that premigratory neural crest cells express these genes and that NSD3 knockdown downregulates (Astn1 and Disp3) and upregulates (Tpm1) their expression, consistent with RNA-seq results. Altogether, this study identifies novel putative regulators of neural crest development and provides insight into the transcriptional consequences of NSD3 in the neural crest, with implications for cancer.
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17
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Parreno J, Amadeo MB, Kwon EH, Fowler VM. Tropomyosin 3.1 Association With Actin Stress Fibers is Required for Lens Epithelial to Mesenchymal Transition. Invest Ophthalmol Vis Sci 2021; 61:2. [PMID: 32492110 PMCID: PMC7415280 DOI: 10.1167/iovs.61.6.2] [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] [Indexed: 01/06/2023] Open
Abstract
Purpose Epithelial to mesenchymal transition (EMT) is a cause of anterior and posterior subcapsular cataracts. Central to EMT is the formation of actin stress fibers. Selective targeting of actin stress fiber-associated tropomyosin (Tpm) in epithelial cells may be a means to prevent stress fiber formation and repress lens EMT. Methods We identified Tpm isoforms in mouse immortalized lens epithelial cells and epithelial and fiber cells from whole lenses by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) followed Sanger sequencing. We focused on the role of one particular tropomyosin isoform, Tpm3.1, in EMT. To induce EMT, we treated cells or native lenses with TGFβ2. To test the function of Tpm3.1, we exposed cells or whole lenses to a Tpm3.1-specific chemical inhibitor, TR100, as well as investigated lenses from Tpm3.1 knockout mice. We examined stress fiber formation by confocal microscopy and assessed EMT progression by analysis of alpha-smooth muscle actin (αSMA) mRNA (real-time RT-PCR), and protein (Western immunoassay [WES]). Results Lens epithelial cells express eight Tpm isoforms. Cell culture studies showed that TGFβ2 treatment results in the upregulation of Tpm3.1, which associates with actin in stress fibers. TR100 prevents stress fiber formation and reduces αSMA in TGFβ2-treated cells. Using an ex vivo lens culture model, TGFβ2 treatment results in stress fiber formation at the basal regions of the epithelial cells. Genetic knockout of Tpm3.1 or treatment of lenses with TR100 prevents basal stress fiber formation and reduces epithelial αSMA levels. Conclusions Targeting specific stress fiber associated tropomyosin isoform, Tpm3.1, is a means to repress lens EMT.
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18
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Boiero Sanders M, Antkowiak A, Michelot A. Diversity from similarity: cellular strategies for assigning particular identities to actin filaments and networks. Open Biol 2020; 10:200157. [PMID: 32873155 PMCID: PMC7536088 DOI: 10.1098/rsob.200157] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The actin cytoskeleton has the particularity of being assembled into many functionally distinct filamentous networks from a common reservoir of monomeric actin. Each of these networks has its own geometrical, dynamical and mechanical properties, because they are capable of recruiting specific families of actin-binding proteins (ABPs), while excluding the others. This review discusses our current understanding of the underlying molecular mechanisms that cells have developed over the course of evolution to segregate ABPs to appropriate actin networks. Segregation of ABPs requires the ability to distinguish actin networks as different substrates for ABPs, which is regulated in three different ways: (1) by the geometrical organization of actin filaments within networks, which promotes or inhibits the accumulation of ABPs; (2) by the identity of the networks' filaments, which results from the decoration of actin filaments with additional proteins such as tropomyosin, from the use of different actin isoforms or from covalent modifications of actin; (3) by the existence of collaborative or competitive binding to actin filaments between two or multiple ABPs. This review highlights that all these effects need to be taken into account to understand the proper localization of ABPs in cells, and discusses what remains to be understood in this field of research.
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Affiliation(s)
- Micaela Boiero Sanders
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Adrien Antkowiak
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Alphée Michelot
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
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19
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Janco M, Dedova I, Bryce NS, Hardeman EC, Gunning PW. Visualizing the in vitro assembly of tropomyosin/actin filaments using TIRF microscopy. Biophys Rev 2020; 12:879-885. [PMID: 32638329 PMCID: PMC7429660 DOI: 10.1007/s12551-020-00720-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/02/2020] [Indexed: 12/23/2022] Open
Abstract
Tropomyosins are elongated alpha-helical proteins that form co-polymers with most actin filaments within a cell and play important roles in the structural and functional diversification of the actin cytoskeleton. How the assembly of tropomyosins along an actin filament is regulated and the kinetics of tropomyosin association with an actin filament is yet to be fully determined. A recent series of publications have used total internal reflection fluorescence (TIRF) microscopy in combination with advanced surface and protein chemistry to visualise the molecular assembly of actin/tropomyosin filaments in vitro. Here, we review the use of the in vitro TIRF assay in the determination of kinetic data on tropomyosin filament assembly. This sophisticated approach has enabled generation of real-time single-molecule data to fill the gap between in vitro bulk assays and in vivo assays of tropomyosin function. The in vitro TIRF assays provide a new foundation for future studies involving multiple actin-binding proteins that will more accurately reflect the physiological protein-protein interactions in cells.
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Affiliation(s)
- Miro Janco
- School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Irina Dedova
- School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Nicole S Bryce
- School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Edna C Hardeman
- School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Peter W Gunning
- School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
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20
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Ostrowska-Podhorodecka Z, Śliwinska M, Reisler E, Moraczewska J. Tropomyosin isoforms regulate cofilin 1 activity by modulating actin filament conformation. Arch Biochem Biophys 2020; 682:108280. [PMID: 31996302 DOI: 10.1016/j.abb.2020.108280] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/22/2020] [Accepted: 01/23/2020] [Indexed: 12/20/2022]
Abstract
Tropomyosin and cofilin are involved in the regulation of actin filament dynamic polymerization and depolymerization. Binding of cofilin changes actin filaments structure, leading to their severing and depolymerization. Non-muscle tropomyosin isoforms were shown before to differentially regulate the activity of cofilin 1; products of TPM1 gene stabilized actin filaments, but products of TPM3 gene promoted cofilin-dependent severing and depolymerization. Here, conformational changes at the longitudinal and lateral interface between actin subunits resulting from tropomyosin and cofilin 1 binding were studied using skeletal actin and yeast wild type and mutant Q41C and S265C actins. Cross-linking of F-actin and fluorescence changes in F-actin labeled with acrylodan at Cys41 (in D-loop) or Cys265 (in H-loop) showed that tropomyosin isoforms differentially regulated cofilin-induced conformational rearrangements at longitudinal and lateral filament interfaces. Tryptic digestion of F-Mg-actin confirmed the differences between tropomyosin isoforms in their regulation of cofilin-dependent changes at actin-actin interfaces. Changes in the fluorescence of AEDANS attached to C-terminal Cys of actin, as well as FRET between Trp residues in actin subdomain 1 and AEDANS, did not show differences in the conformation of the C-terminal segment of F-actin in the presence of different tropomyosins ± cofilin 1. Therefore, actin's D- and H-loop are the sites involved in regulation of cofilin activity by tropomyosin isoforms.
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Affiliation(s)
- Zofia Ostrowska-Podhorodecka
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Poland; Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Małgorzata Śliwinska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Poland
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
; Department of Molecular Biology Institute, University of California, Los Angeles, USA
| | - Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Poland.
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