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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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Leveraging cellular mechano-responsiveness for cancer therapy. Trends Mol Med 2021; 28:155-169. [PMID: 34973934 DOI: 10.1016/j.molmed.2021.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/30/2021] [Accepted: 11/30/2021] [Indexed: 12/21/2022]
Abstract
Cells sense the biophysical properties of the tumor microenvironment (TME) and adopt these signals in their development, progression, and metastatic dissemination. Recent work highlights the mechano-responsiveness of cells in tumors and the underlying mechanisms. Furthermore, approaches to mechano-modulating diverse types of cell have emerged aiming to inhibit tumor growth and metastasis. These include targeting mechanosensitive machineries in cancer cells to induce apoptosis, intervening matrix stiffening incurred by cancer-associated fibroblasts (CAFs) in both primary and metastatic tumor sites, and modulating matrix mechanics to improve immune cell therapeutic efficacy. This review is envisaged to help scientists and clinicians in cancer research to advance understanding of the cellular mechano-responsiveness in TME, and to harness these concepts for cancer mechanotherapies.
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Amer M, Shi L, Wolfenson H. The 'Yin and Yang' of Cancer Cell Growth and Mechanosensing. Cancers (Basel) 2021; 13:4754. [PMID: 34638240 PMCID: PMC8507527 DOI: 10.3390/cancers13194754] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/07/2021] [Accepted: 09/16/2021] [Indexed: 01/06/2023] Open
Abstract
In cancer, two unique and seemingly contradictory behaviors are evident: on the one hand, tumors are typically stiffer than the tissues in which they grow, and this high stiffness promotes their malignant progression; on the other hand, cancer cells are anchorage-independent-namely, they can survive and grow in soft environments that do not support cell attachment. How can these two features be consolidated? Recent findings on the mechanisms by which cells test the mechanical properties of their environment provide insight into the role of aberrant mechanosensing in cancer progression. In this review article, we focus on the role of high stiffness on cancer progression, with particular emphasis on tumor growth; we discuss the mechanisms of mechanosensing and mechanotransduction, and their dysregulation in cancerous cells; and we propose that a 'yin and yang' type phenomenon exists in the mechanobiology of cancer, whereby a switch in the type of interaction with the extracellular matrix dictates the outcome of the cancer cells.
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Affiliation(s)
- Malak Amer
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Lidan Shi
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Haguy Wolfenson
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
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Saikia M, Paul S, Chakraborty S. Role of microRNA in forming breast carcinoma. Life Sci 2020; 259:118256. [DOI: 10.1016/j.lfs.2020.118256] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/31/2020] [Accepted: 08/08/2020] [Indexed: 12/19/2022]
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Liu W, Cai T, Li L, Chen H, Chen R, Zhang M, Zhang W, Zhao L, Xiong H, Qin P, Gao X, Jiang Q. MiR-200a Regulates Nasopharyngeal Carcinoma Cell Migration and Invasion by Targeting MYH10. J Cancer 2020; 11:3052-3060. [PMID: 32226520 PMCID: PMC7086266 DOI: 10.7150/jca.40438] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/04/2020] [Indexed: 12/17/2022] Open
Abstract
Nasopharyngeal carcinoma (NPC), is one of the most common malignant tumor in southern China and southeast Asia. MYH10 is a coding gene of the NMMHC-IIB protein. Previous studies have shown that MYH10 expression was up-regulated in breast cancer, glioma and meningioma. Moreover, it was targeted by miR200 family. However, no relevant studies have been found in NPC. In present study, we found in 48 NPC specimens, MYH10 level was lower in most cancer areas than that in the adjacent normal tissue. Moreover, the depletion of MYH10 can promote the migration and invasion of NPC. In addition, we demonstrated that miR-200a has the strongest regulation to MYH10 among miR-200 family. miR-200a mimics could decrease MYH10 expression, while miR-200a inhibitor increase MYH10 expression. Next, we found that miR-200a bound directly to MYH10 using Dual-luciferase reporter. Finally, it was demonstrated that siMYH10 could reverse the effect of miR-200a inhibitor on NPC cell migration and invasion. Taken together, it can be concluded that MYH10 is lowly expressed in NPC compared with adjacent tissues, and the loss of MYH10 can promote the migration and invasion of NPC cells; Among the miR-200 family, miR-200a has the strongest regulatory effect on MYH10; MYH10 is a direct target gene of miR200a, and miR200a targets MYH10 to regulate the migration and invasion of NPC cells.
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Affiliation(s)
- Wenya Liu
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150.,Department of Pathology, the First Affiliated Hospital, Anhui Medical University, Hefei, China 230022
| | - Tonghui Cai
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
| | - Lingjun Li
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
| | - Hui Chen
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
| | - Ruichao Chen
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
| | - Minfen Zhang
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
| | - Wei Zhang
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
| | - Li Zhao
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
| | - Hanzhen Xiong
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
| | - Ping Qin
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
| | - Xingcheng Gao
- The First Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 511436
| | - Qingping Jiang
- Department of Pathology, the Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, China 510150
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Impact of the actin cytoskeleton on cell development and function mediated via tropomyosin isoforms. Semin Cell Dev Biol 2019; 102:122-131. [PMID: 31630997 DOI: 10.1016/j.semcdb.2019.10.004] [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: 06/21/2019] [Revised: 10/03/2019] [Accepted: 10/04/2019] [Indexed: 01/07/2023]
Abstract
The physiological function of actin filaments is challenging to dissect because of the pleiotropic impact of global disruption of the actin cytoskeleton. Tropomyosin isoforms have provided a unique opportunity to address this issue. A substantial fraction of actin filaments in animal cells consist of co-polymers of actin with specific tropomyosin isoforms which determine the functional capacity of the filament. Genetic manipulation of the tropomyosins has revealed isoform specific roles and identified the physiological function of the different actin filament types based on their tropomyosin isoform composition. Surprisingly, there is remarkably little redundancy between the tropomyosins resulting in highly penetrant impacts of both ectopic overexpression and knockout of isoforms. The physiological roles of the tropomyosins cover a broad range from development and morphogenesis to cell migration and specialised tissue function and human diseases.
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Changes in lncRNAs and related genes in β-thalassemia minor and β-thalassemia major. Front Med 2017; 11:74-86. [DOI: 10.1007/s11684-017-0503-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 11/24/2016] [Indexed: 12/15/2022]
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Panzetta V, De Menna M, Musella I, Pugliese M, Quarto M, Netti PA, Fusco S. X-rays effects on cytoskeleton mechanics of healthy and tumor cells. Cytoskeleton (Hoboken) 2016; 74:40-52. [DOI: 10.1002/cm.21334] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 08/09/2016] [Accepted: 08/15/2016] [Indexed: 12/15/2022]
Affiliation(s)
- Valeria Panzetta
- Center for Advanced Biomaterials for Health Care@CRIB - Istituto Italiano di Tecnologia; Largo Barsanti e Matteucci n. 53 Napoli 80125 Italy
| | - Marta De Menna
- Department of Experimental and Clinic Medicine; University of Catanzaro Magna Graecia; Catanzaro Italy
| | - Ida Musella
- Center for Advanced Biomaterials for Health Care@CRIB - Istituto Italiano di Tecnologia; Largo Barsanti e Matteucci n. 53 Napoli 80125 Italy
| | - Mariagabriella Pugliese
- Dipartimento di Fisica; Università Federico II and INFN-Sezione di Napoli; Monte S. Angelo, Via Cintia Napoli 80126 Italy
| | - Maria Quarto
- Dipartimento di Fisica; Università Federico II and INFN-Sezione di Napoli; Monte S. Angelo, Via Cintia Napoli 80126 Italy
| | - Paolo A. Netti
- Center for Advanced Biomaterials for Health Care@CRIB - Istituto Italiano di Tecnologia; Largo Barsanti e Matteucci n. 53 Napoli 80125 Italy
- Interdisciplinary Research Centre on Biomaterials (CRIB), University of Napoli Federico II; P.le Tecchio 80 Napoli 80125 Italy
| | - Sabato Fusco
- Center for Advanced Biomaterials for Health Care@CRIB - Istituto Italiano di Tecnologia; Largo Barsanti e Matteucci n. 53 Napoli 80125 Italy
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Glass JJ, Phillips PA, Gunning PW, Stehn JR. Hypoxia alters the recruitment of tropomyosins into the actin stress fibres of neuroblastoma cells. BMC Cancer 2015; 15:712. [PMID: 26475688 PMCID: PMC4608101 DOI: 10.1186/s12885-015-1741-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/09/2015] [Indexed: 01/27/2023] Open
Abstract
Background Neuroblastoma is the most common extracranial solid tumor of childhood. The heterogeneous microenvironment of solid tumors contains hypoxic regions associated with poor prognosis and chemoresistance. Hypoxia implicates the actin cytoskeleton through its essential roles in motility, invasion and proliferation. However, hypoxia-induced changes in the actin cytoskeleton have only recently been observed in human cells. Tropomyosins are key regulators of the actin cytoskeleton and we hypothesized that tropomyosins may mediate hypoxic phenotypes. Methods Neuroblastoma (SH-EP) cells were incubated ± hypoxia (1 % O2, 5 % CO2) for up to 144 h, before examining the cytoskeleton by confocal microscopy and Western blotting. Results Hypoxic cells were characterized by a more organized actin cytoskeleton and a reduced ability to degrade gelatin substrates. Hypoxia significantly increased mean actin filament bundle width (72 h) and actin filament length (72–96 h). This correlated with increased hypoxic expression and filamentous organization of stabilizing tropomyosins Tm1 and Tm2. However, isoform specific changes in tropomyosin expression were more evident at 96 h. Conclusions This study demonstrates hypoxia-induced changes in the recruitment of high molecular weight tropomyosins into the actin stress fibres of a human cancer. While hypoxia induced clear changes in actin organization compared with parallel normoxic cultures of neuroblastoma, the precise role of tropomyosins in this hypoxic actin reorganization remains to be determined. Electronic supplementary material The online version of this article (doi:10.1186/s12885-015-1741-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joshua J Glass
- Oncology Research Unit, School of Medical Sciences, UNSW Australia, Room 229, Wallace Wurth Building, Sydney, NSW, 2052, Australia. .,Current address: ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and Department of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, 3010, Australia.
| | - Phoebe A Phillips
- Pancreatic Cancer Translational Research Group, Lowy Cancer Research Centre, UNSW Australia, Sydney, NSW, 2052, Australia.
| | - Peter W Gunning
- Oncology Research Unit, School of Medical Sciences, UNSW Australia, Room 229, Wallace Wurth Building, Sydney, NSW, 2052, Australia.
| | - Justine R Stehn
- Oncology Research Unit, School of Medical Sciences, UNSW Australia, Room 229, Wallace Wurth Building, Sydney, NSW, 2052, Australia.
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Gunning PW, Hardeman EC, Lappalainen P, Mulvihill DP. Tropomyosin - master regulator of actin filament function in the cytoskeleton. J Cell Sci 2015; 128:2965-74. [PMID: 26240174 DOI: 10.1242/jcs.172502] [Citation(s) in RCA: 169] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Tropomyosin (Tpm) isoforms are the master regulators of the functions of individual actin filaments in fungi and metazoans. Tpms are coiled-coil parallel dimers that form a head-to-tail polymer along the length of actin filaments. Yeast only has two Tpm isoforms, whereas mammals have over 40. Each cytoskeletal actin filament contains a homopolymer of Tpm homodimers, resulting in a filament of uniform Tpm composition along its length. Evidence for this 'master regulator' role is based on four core sets of observation. First, spatially and functionally distinct actin filaments contain different Tpm isoforms, and recent data suggest that members of the formin family of actin filament nucleators can specify which Tpm isoform is added to the growing actin filament. Second, Tpms regulate whole-organism physiology in terms of morphogenesis, cell proliferation, vesicle trafficking, biomechanics, glucose metabolism and organ size in an isoform-specific manner. Third, Tpms achieve these functional outputs by regulating the interaction of actin filaments with myosin motors and actin-binding proteins in an isoform-specific manner. Last, the assembly of complex structures, such as stress fibers and podosomes involves the collaboration of multiple types of actin filament specified by their Tpm composition. This allows the cell to specify actin filament function in time and space by simply specifying their Tpm isoform composition.
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Affiliation(s)
- Peter W Gunning
- School of Medical Sciences, UNSW Australia, Sydney 2052, Australia
| | - Edna C Hardeman
- School of Medical Sciences, UNSW Australia, Sydney 2052, Australia
| | - Pekka Lappalainen
- Institute of Biotechnology, University of Helsinki, Helsinki, 00014, Finland
| | - Daniel P Mulvihill
- School of Biosciences, Stacey Building, University of Kent, Canterbury, Kent CT2 7NJ, UK
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PANZETTA VALERIA, DE MENNA MARTA, BUCCI DEBORA, GIOVANNINI VITTORIA, PUGLIESE MARIAGABRIELLA, QUARTO MARIA, FUSCO SABATO, NETTI PAOLO. X-RAY IRRADIATION AFFECTS MORPHOLOGY, PROLIFERATION AND MIGRATION RATE OF HEALTHY AND CANCER CELLS. J MECH MED BIOL 2015. [DOI: 10.1142/s0219519415400229] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cytoskeleton plays a central role in many cellular processes, such as migration, adhesion and proliferation. Alterations of its structural properties are commonly associated with different diseases (malignancy, cardiac hypertrophy, etc.). In this work, we studied the effects of X-radiations on cytoskeleton architecture of two cell lines: BALBc/3T3 and Simian virus 40-transformed BALBc/3T3 (SVT2) cells. In agreement with the current literature, we observed reduced adhesion and increased motility of SVT2 cells respect to non-transformed BALBc/3T3. In addition, we showed that two different doses of X-rays (1 and 2 Gy) increased cell-dish adhesiveness and reduced cell proliferation and cell motility of transformed cells, whereas minor effects were measured on the normal counterpart. These results suggested that low doses or fractioning of X-rays may have a normalization effect on the investigated parameters for the transformed cell phenotype.
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Affiliation(s)
- VALERIA PANZETTA
- Center for Advanced Biomaterials for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci, 53, 80125 Napoli, Italy
| | - MARTA DE MENNA
- Interdisciplinary Research Centre on Biomaterials, Federico II University of Naples, Piazzale Tecchio, 80, 80126, Napoli, Italy
| | - DEBORA BUCCI
- Interdisciplinary Research Centre on Biomaterials, Federico II University of Naples, Piazzale Tecchio, 80, 80126, Napoli, Italy
| | - VITTORIA GIOVANNINI
- Interdisciplinary Research Centre on Biomaterials, Federico II University of Naples, Piazzale Tecchio, 80, 80126, Napoli, Italy
| | - MARIAGABRIELLA PUGLIESE
- Dipartimento di Fisica, Università Federico II and INFN-Sezione di Napoli, Monte S. Angelo, Via Cintia, 80126 Napoli, Italy
| | - MARIA QUARTO
- Dipartimento di Fisica, Università Federico II and INFN-Sezione di Napoli, Monte S. Angelo, Via Cintia, 80126 Napoli, Italy
| | - SABATO FUSCO
- Center for Advanced Biomaterials for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci, 53, 80125 Napoli, Italy
| | - PAOLO NETTI
- Center for Advanced Biomaterials for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci, 53, 80125 Napoli, Italy
- Interdisciplinary Research Centre on Biomaterials, Federico II University of Naples, Piazzale Tecchio, 80, 80126, Napoli, Italy
- Dipartimento di Ingegneria dei Materiali e della Produzione, Universita di Napoli Federico II, 'Piazzale Tecchio 80, 80126, Napoli, Italy
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Regulation of breast cancer and bone metastasis by microRNAs. DISEASE MARKERS 2013; 35:369-87. [PMID: 24191129 PMCID: PMC3809754 DOI: 10.1155/2013/451248] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/17/2013] [Accepted: 08/27/2013] [Indexed: 01/05/2023]
Abstract
Breast cancer progression including bone metastasis is a complex process involving numerous changes in gene expression and function. MicroRNAs (miRNAs) are small endogenous noncoding RNAs that regulate gene expression by targeting protein-coding mRNAs posttranscriptionally, often affecting a number of gene targets simultaneously. Alteration in expression of miRNAs is common in human breast cancer, possessing with either oncogenic or tumor suppressive activity. The expression and the functional role of several miRNAs (miR-206, miR-31, miR-27a/b, miR-21, miR-92a, miR-205, miR-125a/b, miR-10b, miR-155, miR-146a/b, miR-335, miR-204, miR-211, miR-7, miR-22, miR-126, and miR-17) in breast cancer has been identified. In this review we summarize the experimentally validated targets of up- and downregulated miRNAs and their regulation in breast cancer and bone metastasis for diagnostic and therapeutic purposes.
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Abstract
In order to metastasize away from the primary tumor site and migrate into adjacent tissues, cancer cells will stimulate cellular motility through the regulation of their cytoskeletal structures. Through the coordinated polymerization of actin filaments, these cells will control the geometry of distinct structures, namely lamella, lamellipodia and filopodia, as well as the more recently characterized invadopodia. Because actin binding proteins play fundamental functions in regulating the dynamics of actin polymerization, they have been at the forefront of cancer research. This review focuses on a subset of actin binding proteins involved in the regulation of these cellular structures and protrusions, and presents some general principles summarizing how these proteins may remodel the structure of actin. The main body of this review aims to provide new insights into how the expression of these actin binding proteins is regulated during carcinogenesis and highlights new mechanisms that may be initiated by the metastatic cells to induce aberrant expression of such proteins.
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Affiliation(s)
- Stephane R Gross
- School of Life and Health Sciences, Aston University, Birmingham, UK.
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Rescue of tropomyosin deficiency in Drosophila and human cancer cells by synaptopodin reveals a role of tropomyosin α in RhoA stabilization. EMBO J 2011; 31:1028-40. [PMID: 22157816 DOI: 10.1038/emboj.2011.464] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 11/23/2011] [Indexed: 12/15/2022] Open
Abstract
Tropomyosins are widespread actin-binding proteins that influence numerous cellular functions including actin dynamics, cell migration, tumour suppression, and Drosophila oocyte development. Synaptopodin is another actin-binding protein with a more restricted expression pattern in highly dynamic cell compartments such as kidney podocyte foot processes, where it promotes RhoA signalling by blocking the Smurf1-mediated ubiquitination of RhoA. Here, we show that synaptopodin has a shorter half-life but shares functional properties with the highly stable tropomyosin. Transgenic expression of synaptopodin restores oskar mRNA localization in Drosophila oocytes mutant for TmII, thereby rescuing germline differentiation and fertility. Synaptopodin restores stress fibres in tropomyosin-deficient human MDA-MB 231 breast cancer cells and TPMα-depleted fibroblasts. Gene silencing of TPMα but not TPMβ causes loss of stress fibres by promoting Smurf1-mediated ubiquitination and proteasomal degradation of RhoA. Functionally, overexpression of synaptopodin or RhoA(K6,7R) significantly reduces MDA-MB 231 cell migration. Our findings elucidate RhoA stabilization by structurally unrelated actin-binding proteins as a conserved mechanism for regulation of stress fibre dynamics and cell motility in a cell type-specific fashion.
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Macfarlane LA, Murphy PR. MicroRNA: Biogenesis, Function and Role in Cancer. Curr Genomics 2011; 11:537-61. [PMID: 21532838 PMCID: PMC3048316 DOI: 10.2174/138920210793175895] [Citation(s) in RCA: 1190] [Impact Index Per Article: 91.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 08/23/2010] [Accepted: 09/06/2010] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs are small, highly conserved non-coding RNA molecules involved in the regulation of gene expression. MicroRNAs are transcribed by RNA polymerases II and III, generating precursors that undergo a series of cleavage events to form mature microRNA. The conventional biogenesis pathway consists of two cleavage events, one nuclear and one cytoplasmic. However, alternative biogenesis pathways exist that differ in the number of cleavage events and enzymes responsible. How microRNA precursors are sorted to the different pathways is unclear but appears to be determined by the site of origin of the microRNA, its sequence and thermodynamic stability. The regulatory functions of microRNAs are accomplished through the RNA-induced silencing complex (RISC). MicroRNA assembles into RISC, activating the complex to target messenger RNA (mRNA) specified by the microRNA. Various RISC assembly models have been proposed and research continues to explore the mechanism(s) of RISC loading and activation. The degree and nature of the complementarity between the microRNA and target determine the gene silencing mechanism, slicer-dependent mRNA degradation or slicer-independent translation inhibition. Recent evidence indicates that P-bodies are essential for microRNA-mediated gene silencing and that RISC assembly and silencing occurs primarily within P-bodies. The P-body model outlines microRNA sorting and shuttling between specialized P-body compartments that house enzymes required for slicer –dependent and –independent silencing, addressing the reversibility of these silencing mechanisms. Detailed knowledge of the microRNA pathways is essential for understanding their physiological role and the implications associated with dysfunction and dysregulation.
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Affiliation(s)
- Leigh-Ann Macfarlane
- Department of Physiology & Biophysics, Faculty of Medicine, Dalhousie University, 5850 College Street, Sir Charles Tupper Medical Building, Halifax, Nova Scotia, B3H 1X5, Canada
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Abstract
The actin cytoskeleton is indispensable for normal cellular function. In particular, several actin-based structures coordinate cellular motility, a process hijacked by tumor cells in order to facilitate their propagation to distant sites. The actin cytoskeleton, therefore, represents a point for chemotherapeutic intervention. The challenge in disrupting the actin cytoskeleton is in preserving actin-driven contraction of cardiac and skeletal muscle. By targeting actin-binding proteins with altered expression in malignancy, it may be possible to achieve tumor-specific toxicity. A number of actin-binding proteins act cooperatively and synergistically to regulate actin structures required for motility. The actin cytoskeleton is characterized by a significant degree of plasticity. Targeting specific actin-binding proteins for chemotherapy will only be successful if no other compensatory mechanisms exist.
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Assinder SJ, Au E, Dong Q, Winnick C. A novel splice variant of the beta-tropomyosin (TPM2) gene in prostate cancer. Mol Carcinog 2010; 49:525-31. [PMID: 20336778 DOI: 10.1002/mc.20626] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Decreased expression of high molecular weight isoforms of tropomyosin (Tm) is associated with oncogenic transformation and is evident in cancers, with isoform Tm1 seemingly an important tumor suppressor. Tm1 expression in prostate cancer has not previously been described. In this study, while demonstrating suppressed levels of Tm1 in the prostate cancer cell lines LNCaP, PC3, and DU-145 compared to normal prostate epithelial cell primary isolates (PrEC), a novel splice variant of the TPM2 gene was identified. Quantitative RT-PCR determined significantly greater levels of the transcript variant in all three prostate cancer cell lines than in normal prostate epithelial cells. Characterization of this novel variant demonstrated it to include exon 6b, previously thought unique to the muscle-specific beta-Tm isoform, with an exon arrangement of 1-2-3-4-5-6a-6b-7-8-10. Inclusion of exon 6b introduces a premature stop codon directly following the 6a-6b exon boundary. Western blot analysis demonstrated the presence of a truncated protein in prostate cancer cell lines that was absent in normal prostate epithelial cells. It is hypothesized that this truncated protein will result in suppression of Tm1 polymer formation required for actin filament association. The lack of Tm polymer-actin association will result in loss of the stable actin microfilament organization and stress fiber formation, a state associated with cell transformation.
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Affiliation(s)
- Stephen J Assinder
- Discipline of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney, Sydney, NSW, Australia
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Abstract
Esophageal carcinogenesis is a multi-stage process, involving a variety of changes in gene expression and physiological structure change. MicroRNAs (miRNAs) are a class of small non-coding endogenous RNA molecules. Recent innovation in miRNAs profiling technology have shed new light on the pathology of esophageal carcinoma (EC), and also heralded great potential for exploring novel biomarkers for both EC diagnosis and treatment. Frequent dysregulation of miRNA in malignancy highlights the study of molecular factors upstream of gene expression following the extensive investigation on elucidating the important role of miRNA in carcinogenesis. We herein present a thorough review of the role of miRNAs in EC, addressing miRNA functions, their putative role as oncogenes or tumor suppressors and their potential target genes. The recent progresses in discovering the quantifiable circulating cancer-associated miRNAs indicate the potential clinical use of miRNAs as novel minimally invasive biomarkers for EC and other cancers. We also discuss the potential role of miRNAs in detection, screening and surveillance of EC as miRNAs can be a potential target in personalized treatment of EC.
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Abstract
MicroRNAs (miRNAs) are small noncoding, double-stranded RNA molecules that can mediate the expression of target genes with complementary sequences. About 5,300 human genes have been implicated as targets for miRNAs, making them one of the most abundant classes of regulatory genes in humans. MiRNAs recognize their target mRNAs based on sequence complementarity and act on them to cause the inhibition of protein translation by degradation of mRNA. Besides contributing to development and normal function, microRNAs have functions in various human diseases. Given the importance of miRNAs in regulating cellular differentiation and proliferation, it is not surprising that their misregulation is linked to cancer. In cancer, miRNAs function as regulatory molecules, acting as oncogenes or tumor suppressors. Amplification or overexpression of miRNAs can down-regulate tumor suppressors or other genes involved in cell differentiation, thereby contributing to tumor formation by stimulating proliferation, angiogenesis, and invasion; i.e., they act as oncogenes. Similarly, miRNAs can down-regulate different proteins with oncogenic activity; i.e., they act as tumor suppressors. This review will highlight the recent discoveries regarding miRNAs and their importance in cancer.
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Khoshnaw SM, Green AR, Powe DG, Ellis IO. MicroRNA involvement in the pathogenesis and management of breast cancer. J Clin Pathol 2009; 62:422-8. [PMID: 19398594 DOI: 10.1136/jcp.2008.060681] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
MicroRNAs (miRNAs) are a highly abundant class of endogenous small non-coding RNAs (18-25 nucleotides in length) that regulate gene expression by targeting protein-coding mRNAs post-transcriptionally. miRNAs have been implicated in cancer development and progression. As miRNAs and their regulatory functions are further revealed, the more the importance of miRNA-directed gene regulation is emphasised. In the human genome, 695 mature miRNAs have been identified, although computational calculation predicts that this may increase to >1000. Deregulation of miRNA expression profiles is thought to be implicated in the pathogenesis of many human cancers including breast tumours. Breast cancer subtypes are observed to have deranged miRNA expression signatures, which makes miRNAs important targets for developing a novel molecular classification of breast cancer and opening avenues for more individualised treatment strategies for patients with breast cancer.
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Affiliation(s)
- S M Khoshnaw
- Department of Histopathology, School of Molecular Medical Sciences, University of Nottingham and Nottingham University Hospitals Trust, Nottingham, UK.
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22
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S100A6 binds to annexin 2 in pancreatic cancer cells and promotes pancreatic cancer cell motility. Br J Cancer 2009; 101:1145-54. [PMID: 19724273 PMCID: PMC2768105 DOI: 10.1038/sj.bjc.6605289] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Background: High levels of S100A6 have been associated with poor outcome in pancreatic cancer patients. The functional role of S100A6 is, however, poorly understood. Methods: Immunoprecipitation followed by two-dimensional gel electrophoresis and mass spectrometry were undertaken to identify S100A6 interacting proteins in pancreatic cancer cells. Immunohistochemistry and coimmunofluorescence were performed to examine expression or colocalisation of proteins. siRNA was used to deplete specific proteins and effects on motility were measured using Boyden Chamber and wound healing assays. Results: Our proteomic screen to identify S100A6 interacting proteins revealed annexin 11, annexin 2, tropomyosin β and a candidate novel interactor lamin B1. Of these, annexin 2 was considered particularly interesting, as, like S100A6, it is expressed early in the development of pancreatic cancer and overexpression occurs with high frequency in invasive cancer. Reciprocal immunoprecipitation confirmed the interaction between annexin 2 and S100A6 and the proteins colocalised, particularly in the plasma membrane of cultured pancreatic cancer cells and primary pancreatic tumour tissue. Analysis of primary pancreatic cancer specimens (n=55) revealed a strong association between high levels of cytoplasmic S100A6 and the presence of annexin 2 in the plasma membrane of cancer cells (P=0.009). Depletion of S100A6 was accompanied by diminished levels of membrane annexin 2 and caused a pronounced reduction in the motility of pancreatic cancer cells. Conclusion: These findings point towards a functional role for S100A6 that may help explain the link between S100A6 expression in pancreatic cancer and aggressive disease.
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Abstract
microRNAs (miRNAs) are highly conserved, non-protein-coding RNAs that function to regulate gene expression. In mammals this regulation is primarily carried out by repression of translation. miRNAs play important roles in homeostatic processes such as development, cell proliferation and cell death. Recently the dysregulation of miRNAs has been linked to cancer initiation and progression, indicating that miRNAs may play roles as tumour suppressor genes or oncogenes. The role of miRNAs in apoptosis is not fully understood, however, evidence is mounting that miRNAs are important in this process. The dysregulation of miRNAs involved in apoptosis may provide a mechanism for cancer development and resistance to cancer therapy. This review examines the biosynthesis of miRNA, the mechanisms of miRNA target regulation and the involvement of miRNAs in the initiation and progression of human cancer. It will include miRNAs involved in apoptosis, specifically those miRNAs involved in the regulation of apoptotic pathways and tumour suppressor/oncogene networks. It will also consider emerging evidence supporting a role for miRNAs in modulating sensitivity to anti-cancer therapy.
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Affiliation(s)
- Niamh Lynam-Lennon
- Department of Surgery, Trinity College Dublin, Trinity Centre for Health Sciences, St. James's Hospital, Dublin 8, Ireland
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Li A, Denlinger DL. Rapid cold hardening elicits changes in brain protein profiles of the flesh fly, Sarcophaga crassipalpis. INSECT MOLECULAR BIOLOGY 2008; 17:565-572. [PMID: 18828842 DOI: 10.1111/j.1365-2583.2008.00827.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Rapid cold hardening (RCH) refers to the enhanced cold tolerance acquired by a brief exposure to a moderately low temperature. Although ecological aspects of this response have been well documented in insects, less is known about the physiological and biochemical mechanisms elicited by RCH. In this study we used two-dimensional electrophoresis to detect differences in brain protein abundance in pharate adults of the flesh fly Sarcophaga crassipalpis, in response to a 2 h RCH exposure at 0 degrees C. Fourteen high abundance proteins that responded to RCH were selected for mass spectrometric identification. Three proteins that increased in abundance during RCH included ATP synthase subunit alpha, a small heat shock protein (smHsp), and tropomyosin-1 isoforms 33/34. Eleven proteins that decreased in abundance or were missing following RCH included several proteins involved in energy metabolism, protein degradation, transcription, actin binding, and cytoskeleton organization. That several proteins increased in abundance during RCH underscores the dynamics of the RCH mechanism and suggests that more than one physiological response likely contribute to RCH. The increase in ATP synthase suggests an elevation of ATP during RCH, and the smHsp increase suggests that at least one of the Hsps is actually mobilized during RCH, rather than after RCH as previously assumed.
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Affiliation(s)
- A Li
- Department of Entomology, The Ohio State University, 318 West 12th Avenue, Columbus, OH 43210, USA
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Verghese ET, Hanby AM, Speirs V, Hughes TA. Small is beautiful: microRNAs and breast cancer-where are we now? J Pathol 2008; 215:214-21. [PMID: 18446835 DOI: 10.1002/path.2359] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
MicroRNAs are a recently discovered class of small regulatory RNAs that influence the stability and translational efficiency of target mRNAs. They have been implicated in an increasing number of biological processes, including neoplasia. Recent studies have shown an involvement for these regulatory molecules in breast cancer. For example, miRNA profiling studies have identified microRNAs that are deregulated in breast cancer. Furthermore, functional studies have uncovered their roles in breast cancer as both tumour suppressor genes (eg miR-335) and oncogenes (eg miR-21). miRNAs deregulated in breast cancer influence the translational regulation of well-established regulatory molecules, such as oestrogen receptor-alpha, which is regulated by miR-206, and novel cancer-related molecules whose functions are not yet fully understood.. Here we present an overview of our current understanding of miRNA in breast cancer.
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Abstract
MicroRNAs (miRNAs) are a class of naturally occurring small non-coding RNAs that target protein-coding mRNAs at the post-transcriptional level. Our previous studies suggest that mir-21 functions as an oncogene and has a role in tumorigenesis, in part through regulation of the tumor suppressor gene tropomyosin 1 (TPM1). Given that TPM1 has been implicated in cell migration, in this study we further investigated the role of mir-21 in cell invasion and tumor metastasis. We found that suppression of mir-21 in metastatic breast cancer MDA-MB-231 cells significantly reduced invasion and lung metastasis. Consistent with this, ectopic expression of TPM1 remarkably reduced cell invasion. Furthermore, we identified two additional direct mir-21 targets, programmed cell death 4 (PDCD4) and maspin, both of which have been implicated in invasion and metastasis. Like TPM1, PDCD4 and maspin also reduced invasiveness of MDA-MB-231 cells. Finally, the expression of PDCD4 and maspin inversely correlated with mir-21 expression in human breast tumor specimens, indicating the potential regulation of PDCD4 and maspin by mir-21 in these tumors. Taken together, the results suggest that, as an oncogenic miRNA, mir-21 has a role not only in tumor growth but also in invasion and tumor metastasis by targeting multiple tumor/metastasis suppressor genes. Therefore, suppression of mir-21 may provide a novel approach for the treatment of advanced cancers.
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The dimensions and composition of stereociliary rootlets in mammalian cochlear hair cells: comparison between high- and low-frequency cells and evidence for a connection to the lateral membrane. J Neurosci 2008; 28:6342-53. [PMID: 18562604 DOI: 10.1523/jneurosci.1154-08.2008] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The sensory bundle of vertebrate cochlear hair cells consists of actin-containing stereocilia that are thought to bend at their ankle during mechanical stimulation. Stereocilia have dense rootlets that extend through the ankle region to anchor them into the cuticular plate. Because this region may be important in bundle stiffness and durability during prolonged stimulation at high frequencies, we investigated the structure and dimensions of rootlets relative to the stereocilia in apical (low-frequency) and basal (high-frequency) regions of rodent cochleae using light and electron microscopy. Their composition was investigated using postembedding immunogold labeling of tropomyosin, spectrin, beta-actin, gamma-actin, espin, and prestin. The rootlets have a thick central core that widens at the ankle, and are embedded in a filamentous meshwork in the cuticular plate. Within a particular frequency region, rootlet length correlates with stereociliary height but between regions it changes disproportionately; apical stereocilia are, thus, approximately twice the height of basal stereocilia in equivalent rows, but rootlet lengths increase much less. Some rootlets contact the tight junctions that underlie the ends of the bundle. Rootlets contain spectrin, tropomyosin, and beta- and gamma-actin, but espin was not detected; spectrin is also evident near the apical and junctional membranes, whereas prestin is confined to the basolateral membrane below the junctions. These data suggest that rootlets strengthen the ankle region to provide durability and may contact with the lateral wall either to give additional anchoring of the stereocilia or to provide a route for interactions between the bundle and the lateral wall.
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Ha HY, Kim JB, Cho IH, Joo HJ, Kim KS, Lee KW, Sunwoo H, Im JY, Lee JK, Hong JH, Han PL. Morphogenetic lung defects of JSAP1-deficient embryos proceeds via the disruptions of the normal expressions of cytoskeletal and chaperone proteins. Proteomics 2008; 8:1071-80. [PMID: 18324732 DOI: 10.1002/pmic.200700815] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Recent studies have shown that JNK/stress-activated protein kinase-associated protein 1 (JSAP1)-deficient mice die from respiratory failure shortly after birth. To understand the underlying mechanism, we investigated the histological appearances and cell type changes in developing jsap1(-/-) lungs between E12.5 and E18.5. At the light microscopic level, no overt abnormality was detected in jsap1(-/-) until E16.5. However, alveoli and airway formations that normally occur after E16.5 were poorly advanced in jsap1(-/-). Despite these morphological defects, surfactant secreting cells labeled by anti-SP-B or anti-SP-C were present in normal ranges in jsap1(-/-) lungs. Smooth muscle alpha-actin expressing cells were also developed in jsap1(-/-) lungs, although actin expression was decreased. The expressions of transcriptional factors, such as, nuclear factor Ib (Nfib), N-myc, and octamer transcriptional factor 1 (Oct-1), which play a critical role in lung morphogenesis, were found to be down-regulated, whereas signal transducer and activator of transcription 3 (Stat3), sonic hedgehog (Shh), and smoothened (Smo) were up-regulated, in jsap1(-/-) lungs at E17.5-E18.5 compared with those in jsap1(+/+) lungs. Proteomics analysis of E17.5 lung identified 39 proteins with altered expressions, which included actin, tropomyosin, myosin light chain, vimentin, heat shock protein (Hsp27), and Hsp84. These results suggest that JSAP1 is required for the normal expressions of cytoskeletal and chaperone proteins in the developing lung, and that impaired expressions of these proteins might cause morphogenetic defects observed in jsap1(-/-) lungs.
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Affiliation(s)
- Hye-Yeong Ha
- Division of Nano Sciences and Brain Disease Research Institute, Ewha Womans University, Seoul, Republic of Korea
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Modulation of miRNA activity in human cancer: a new paradigm for cancer gene therapy? Cancer Gene Ther 2008; 15:341-55. [PMID: 18369380 DOI: 10.1038/cgt.2008.8] [Citation(s) in RCA: 183] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
MicroRNAs (miRNAs) were discovered more than a decade ago as noncoding, single-stranded small RNAs (approximately 22 nucleotides) that control the timed gene expression pattern in Caenorhabditis elegans life cycle. A number of these evolutionarily conserved, endogenous miRNAs have been shown to regulate mammalian cell growth, differentiation and apoptosis. miRNAs are multispecific by nature. The individual miRNA is capable of modulating the expression of a network of mRNAs that it binds by imperfect sequence complementarity. Human cancers commonly exhibit an altered expression profile of miRNAs with oncogenic (miR-21, miR-106a and miR-155) or tumor-suppressive (let-7, miR-15a/16, miR-34a and miR-143/145) activity. As consistent with the natural function of miRNAs in specifying cellular phenotype, miRNA-based cancer gene therapy offers the theoretical appeal of targeting multiple gene networks that are controlled by a single, aberrantly expressed miRNA. Reconstitution of tumor-suppressive miRNA, or sequence-specific knockdown of oncogenic miRNAs by 'antagomirs,' has produced favorable antitumor outcomes in experimental models. We discuss pending issues that need to be resolved prior to the consideration of miRNA-based experimental cancer gene therapy. These include the need for definitive mRNA target validation, our incomplete understanding of rate-limiting cellular components that impact the efficiency of this posttranscriptional gene-silencing phenomenon, the possibility for nonspecific immune activation and the lack of a defined, optimal mode of delivery.
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Gunning P, O'Neill G, Hardeman E. Tropomyosin-based regulation of the actin cytoskeleton in time and space. Physiol Rev 2008; 88:1-35. [PMID: 18195081 DOI: 10.1152/physrev.00001.2007] [Citation(s) in RCA: 352] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Tropomyosins are rodlike coiled coil dimers that form continuous polymers along the major groove of most actin filaments. In striated muscle, tropomyosin regulates the actin-myosin interaction and, hence, contraction of muscle. Tropomyosin also contributes to most, if not all, functions of the actin cytoskeleton, and its role is essential for the viability of a wide range of organisms. The ability of tropomyosin to contribute to the many functions of the actin cytoskeleton is related to the temporal and spatial regulation of expression of tropomyosin isoforms. Qualitative and quantitative changes in tropomyosin isoform expression accompany morphogenesis in a range of cell types. The isoforms are segregated to different intracellular pools of actin filaments and confer different properties to these filaments. Mutations in tropomyosins are directly involved in cardiac and skeletal muscle diseases. Alterations in tropomyosin expression directly contribute to the growth and spread of cancer. The functional specificity of tropomyosins is related to the collaborative interactions of the isoforms with different actin binding proteins such as cofilin, gelsolin, Arp 2/3, myosin, caldesmon, and tropomodulin. It is proposed that local changes in signaling activity may be sufficient to drive the assembly of isoform-specific complexes at different intracellular sites.
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Affiliation(s)
- Peter Gunning
- Oncology Research Unit, The Children's Hospital at Westmead, and Muscle Development Unit, Children's Medical Research Institute, Westmead; New South Wales, Australia.
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31
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Gunning P. Emerging Issues for Tropomyosin Structure, Regulation, Function and Pathology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 644:293-8. [DOI: 10.1007/978-0-387-85766-4_22] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Houle F, Poirier A, Dumaresq J, Huot J. DAP kinase mediates the phosphorylation of tropomyosin-1 downstream of the ERK pathway, which regulates the formation of stress fibers in response to oxidative stress. J Cell Sci 2007; 120:3666-77. [PMID: 17895359 DOI: 10.1242/jcs.003251] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Endothelial cells are actively involved in regulating the exchanges between blood and tissues. This function is tightly dependent on actin cytoskeleton dynamics and is challenged by a wide variety of stimuli, including oxidative stress. In endothelial cells, oxidative stress quickly activates the extracellular-signal-regulated kinase (ERK) MAP kinase, which results in the phosphorylation of tropomyosin. Here, we investigated further the mechanisms of tropomyosin phosphorylation and its function in actin remodeling. We identified, for the first time, death-associated protein kinase 1 (DAP kinase 1) as the kinase that phosphorylates tropomyosin-1 in response to ERK activation by hydrogen peroxide (H(2)O(2)). We also report that the phosphorylation of tropomyosin-1 mediated by DAP kinase occurs on Ser283. Moreover, the expression of the pseudophosphorylated tropomyosin mutant Ser283Glu triggers by itself the formation of stress fibers in untreated cells, and the effect is maintained in H(2)O(2)-treated cells in which DAP kinase expression is knocked-down by siRNA. By contrast, the expression of the nonphosphorylatable tropomyosin mutant Ser283Ala is not associated with stress fibers and leads to membrane blebbing in response to H(2)O(2). Our finding that tropomyosin-1 is phosphorylated downstream of ERK and DAP kinase and that it helps regulate the formation of stress fibers will aid understanding the role of this protein in regulating the endothelial functions associated with cytoskeletal remodeling.
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Affiliation(s)
- François Houle
- Le Centre de recherche en cancérologie de l'Université Laval, 9 rue McMahon, Québec G1R 2J6, Canada
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Tropomyosins as interpreters of the signalling environment to regulate the local cytoskeleton. Semin Cancer Biol 2007; 18:35-44. [PMID: 17942320 DOI: 10.1016/j.semcancer.2007.08.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Accepted: 08/28/2007] [Indexed: 01/11/2023]
Abstract
A key regulator of cell morphology is the actin cytoskeleton and it has long been appreciated that the cytoskeleton is characteristically altered in cancer. Actin is organized into polymeric structures with distinct dynamics which in turn participate in a wide variety of cell processes including adhesion, migration, cell division and apoptosis. Despite displaying an altered actin cytoskeleton, transformed cells retain--and in many cases increase--their ability to adhere, move, divide and respond to apoptotic stimuli. Thus cancer cells maintain responsive actin cytoskeletons. Actin dynamics are regulated by numerous actin-binding proteins and chief among these are the tropomyosins which are core components of the microfilament. Recent advances in genomic and proteomic profiling confirm that Tm expression profiles are profoundly changed in transformed cells. It is therefore timely to review the role of Tms in the regulation of actin dynamics that pertain to crucial phenotypic changes in cancer. In this review we discuss how actin filaments containing different Tm isoforms respond to the activation of cell signalling pathways and consider the implications of this for cancer progression and therapy.
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34
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Orre LM, Pernemalm M, Lengqvist J, Lewensohn R, Lehtiö J. Up-regulation, modification, and translocation of S100A6 induced by exposure to ionizing radiation revealed by proteomics profiling. Mol Cell Proteomics 2007; 6:2122-31. [PMID: 17785350 DOI: 10.1074/mcp.m700202-mcp200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The cellular response to genotoxic stress is a complex cascade of events including altered protein expression, interactions, modifications, and relocalization, leading to cell cycle arrest and DNA repair or to apoptosis. p53 protein has a central role in this process, and p53 status is an important factor in the response of a tumor to genotoxic anticancer therapy. We studied p53-related changes postexposure to ionizing radiation using top-down mass spectrometry. Initially two cell lines were compared, HCT116 p53 wild type (wt) and p53(-/-), in a time course study postirradiation. In the p53 wt cell line a striking increase of a 10.2-kDa protein was detected, and this protein was identified with MS/MS analysis as S100A6. Further MS profiling led to detection of two post-translationally modified variants of S100A6, namely glutathionylated and cysteinylated forms. In p53 wt cells, a specific shift from glutathionylated to cysteinylated S100A6 occurred postirradiation. The p53 dependence of this specific change in protein level and modification pattern of S100A6 postirradiation was confirmed in a panel of four lung cancer cell lines (H23, U1810, H69, and A549) with different p53 status and using small interfering RNA against p53. Interestingly the closely related S100 family protein S100A4 showed the same changes in modification pattern post-ionizing radiation in the p53 wt lung cancer cell line, and S100A4 also showed p53-dependent expression. Using confocal microscopy, relocalization of S100A6 from nucleus to cytosol and a colocalization with tropomyosin in stress fibers was detected in A549 cells postirradiation. This relocalization coincided with the change in S100A6 modification pattern. Based on these results, we suggest that S100A6 and S100A4 are regulated via redox modifications in vivo and that these proteins are involved in the cellular response to genotoxic stress.
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Affiliation(s)
- Lukas M Orre
- Karolinska Biomics Center (KBC), Karolinska Institutet, Z5 plan 02, Karolinska University Hospital Solna, 171 76 Stockholm Sweden
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Zhu S, Si ML, Wu H, Mo YY. MicroRNA-21 targets the tumor suppressor gene tropomyosin 1 (TPM1). J Biol Chem 2007; 282:14328-36. [PMID: 17363372 DOI: 10.1074/jbc.m611393200] [Citation(s) in RCA: 806] [Impact Index Per Article: 47.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
MicroRNAs are small noncoding RNA molecules that control expression of target genes. Our previous studies show that mir-21 is overexpressed in tumor tissues compared with the matched normal tissues. Moreover, suppression of mir-21 by antisense oligonucleotides inhibits tumor cell growth both in vitro and in vivo. However, it remains largely unclear as to how mir-21 affects tumor growth, because our understanding of mir-21 targets is limited. In this study, we performed two-dimensional differentiation in-gel electrophoresis of tumors treated with anti-mir-21 and identified the tumor suppressor tropomyosin 1 (TPM1) as a potential mir-21 target. In agreement with this, there is a putative mir-21 binding site at the 3'-untranslated region (3'-UTR) of TPM1 variants V1 and V5. Thus, we cloned the 3'-UTR of TPM1 into a luciferase reporter and found that although mir-21 down-regulated the luciferase activity, anti-mir-21 up-regulated it. Moreover, deletion of the mir-21 binding site abolished the effect of mir-21 on the luciferase activity, suggesting that this mir-21 binding site is critical. Western blot with the cloned TPM1-V1 plus the 3'-UTR indicated that TPM1 protein level was also regulated by mir-21, whereas real-time quantitative reverse transcription-PCR revealed no difference at the mRNA level, suggesting translational regulation. Finally, overexpression of TPM1 in breast cancer MCF-7 cells suppressed anchorage-independent growth. Thus, down-regulation of TPM1 by mir-21 may explain, at least in part, why suppression of mir-21 can inhibit tumor growth, further supporting the notion that mir-21 functions as an oncogene.
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Affiliation(s)
- Shuomin Zhu
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL 62794, USA
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36
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Harada T, Kuramitsu Y, Makino A, Fujimoto M, Iizuka N, Hoshii Y, Takashima M, Tamesa M, Nishimura T, Takeda S, Abe T, Yoshino S, Oka M, Nakamura K. Expression of tropomyosin alpha 4 chain is increased in esophageal squamous cell carcinoma as evidenced by proteomic profiling by two-dimensional electrophoresis and liquid chromatography-mass spectrometry/mass spectrometry. Proteomics Clin Appl 2007; 1:215-23. [PMID: 21136671 DOI: 10.1002/prca.200600609] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Indexed: 01/27/2023]
Abstract
To identify proteins associated with esophageal carcinogenesis, we performed protein profiling of 16 esophageal squamous cell carcinomas (ESCCs) and paired noncancerous tissues by 2-DE and MS/MS. In cancerous tissues, three spots showed significant up-regulation in the amount of protein, while eight spots were significantly down-regulated. The identities of the spots were determined by PMF with LC-MS/MS and were confirmed by immunoblotting. The up-regulated proteins were tropomyosin alpha 4 chain, transgelin, and pyruvate kinase. The down-regulated proteins were serum albumin precursor, isoforms of annexin A1, tropomyosin beta chain, 14-3-3 protein sigma, and isoforms of serotransferrin precursor. In all 16 cases, up-regulation of the tropomyosin alpha 4 chain was confirmed by immunoblotting. Localization of the tropomyosin alpha 4 chain in ESCC cells and adjacent fibroblasts was confirmed by immunohistochemistry.
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Affiliation(s)
- Toshio Harada
- Department of Digestive Surgery and Surgical Oncology (Department of Surgery II), Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan; Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan
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Gunning PW, Schevzov G, Kee AJ, Hardeman EC. Tropomyosin isoforms: divining rods for actin cytoskeleton function. Trends Cell Biol 2006; 15:333-41. [PMID: 15953552 DOI: 10.1016/j.tcb.2005.04.007] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2004] [Revised: 04/12/2005] [Accepted: 04/26/2005] [Indexed: 01/14/2023]
Abstract
Actin filament functional diversity is paralleled by variation in the composition of isoforms of tropomyosin in these filaments. Although the role of tropomyosin is well understood in skeletal muscle, where it regulates the actin-myosin interaction, its role in the cytoskeleton has been obscure. The intracellular sorting of tropomyosin isoforms indicated a role in spatial specialization of actin filament function. Genetic manipulation and protein chemistry studies have confirmed that these isoforms are functionally distinct. Tropomyosins differ in their recruitment of myosin motors and their interaction with actin filament regulators such as ADF-cofilin. Tropomyosin isoforms have therefore provided a powerful mechanism to diversify actin filament function in different intracellular compartments.
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Affiliation(s)
- Peter W Gunning
- Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead NSW 2145, Australia.
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38
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Prasad GL. Regulation of the Expression of Tropomyosins and Actin Cytoskeleton by ras Transformation. Methods Enzymol 2006; 407:410-22. [PMID: 16757342 DOI: 10.1016/s0076-6879(05)07034-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
Neoplastic transformation by Ras proteins markedly suppresses the expression of certain isoforms of tropomyosins (TMs), which are important regulators of actin cytoskeleton. Downregulation of TMs and other actin-associated proteins is believed to result in the assembly of aberrant cytoskeleton, which in turn contributes to the malignant transformation by Ras. Oncogenic activation of ras, in addition to suppressing TMs by means of epigenetic mechanisms, also rapidly inhibits their cytoskeletal fractionation, leading to the disruption of cytoskeleton. Restoration of expression of certain isoforms of TMs reorganizes microfilaments and suppresses the malignant growth of ras-transformed cells. This chapter discusses some of the approaches to the analysis of TM isoform expression in normal and ras-transformed cells.
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Affiliation(s)
- G L Prasad
- Department of General Surgery, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
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39
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Varga AE, Stourman NV, Zheng Q, Safina AF, Quan L, Li X, Sossey-Alaoui K, Bakin AV. Silencing of the Tropomyosin-1 gene by DNA methylation alters tumor suppressor function of TGF-beta. Oncogene 2005; 24:5043-52. [PMID: 15897890 DOI: 10.1038/sj.onc.1208688] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Loss of actin stress fibers has been associated with cell transformation and metastasis. TGF-beta induction of stress fibers in epithelial cells requires high molecular weight tropomyosins encoded by TPM1 and TPM2 genes. Here, we investigated the mechanism underlying the failure of TGF-beta to induce stress fibers and inhibit cell migration in metastatic cells. RT-PCR analysis in carcinoma cell lines revealed a significant reduction in TPM1 transcripts in metastatic MDA-MB-231, MDA-MB-435 and SW620 cell lines. Treatment of these cells with demethylating agent 5-aza-2'-deoxycytidine (5-aza-dC) increased mRNA levels of TPM1 with no effect on TPM2. Importantly, 5-aza-dC treatment of MDA-MB-231 cells restored TGF-beta induction of TPM1 and formation of stress fibers. Forced expression of TPM1 by using Tet-Off system increased stress fibers in MDA-MB-231 cells and reduced cell migration. A potential CpG island spanning the TPM1 proximal promoter, exon 1, and the beginning of intron 1 was identified. Bisulfite sequencing showed significant cytosine methylation in metastatic cell lines that correlated with a reduced expression of TPM1. Together these results suggest that epigenetic suppression of TPM1 may alter TGF-beta tumor suppressor function and contribute to metastatic properties of tumor cells.
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Affiliation(s)
- Andrea E Varga
- Department of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
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40
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Schevzov G, Bryce NS, Almonte-Baldonado R, Joya J, Lin JJC, Hardeman E, Weinberger R, Gunning P. Specific features of neuronal size and shape are regulated by tropomyosin isoforms. Mol Biol Cell 2005; 16:3425-37. [PMID: 15888546 PMCID: PMC1165423 DOI: 10.1091/mbc.e04-10-0951] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Revised: 03/15/2005] [Accepted: 04/27/2005] [Indexed: 12/15/2022] Open
Abstract
Spatially distinct populations of microfilaments, characterized by different tropomyosin (Tm) isoforms, are present within a neuron. To investigate the impact of altered tropomyosin isoform expression on neuronal morphogenesis, embryonic cortical neurons from transgenic mice expressing the isoforms Tm3 and Tm5NM1, under the control of the beta-actin promoter, were cultured in vitro. Exogenously expressed Tm isoforms sorted to different subcellular compartments with Tm5NM1 enriched in filopodia and growth cones, whereas the Tm3 was more broadly localized. The Tm5NM1 neurons displayed significantly enlarged growth cones accompanied by an increase in the number of dendrites and axonal branching. In contrast, Tm3 neurons displayed inhibition of neurite outgrowth. Recruitment of Tm5a and myosin IIB was observed in the peripheral region of a significant number of Tm5NM1 growth cones. We propose that enrichment of myosin IIB increases filament stability, leading to the enlarged growth cones. Our observations support a role for different tropomyosin isoforms in regulating interactions with myosin and thereby regulating morphology in specific intracellular compartments.
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Affiliation(s)
- Galina Schevzov
- Oncology Research Unit, The Children's Hospital at Westmead, Westmead NSW 2145, Australia
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41
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Kee AJ, Schevzov G, Nair-Shalliker V, Robinson CS, Vrhovski B, Ghoddusi M, Qiu MR, Lin JJC, Weinberger R, Gunning PW, Hardeman EC. Sorting of a nonmuscle tropomyosin to a novel cytoskeletal compartment in skeletal muscle results in muscular dystrophy. ACTA ACUST UNITED AC 2004; 166:685-96. [PMID: 15337777 PMCID: PMC2172434 DOI: 10.1083/jcb.200406181] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Tropomyosin (Tm) is a key component of the actin cytoskeleton and >40 isoforms have been described in mammals. In addition to the isoforms in the sarcomere, we now report the existence of two nonsarcomeric (NS) isoforms in skeletal muscle. These isoforms are excluded from the thin filament of the sarcomere and are localized to a novel Z-line adjacent structure. Immunostained cross sections indicate that one Tm defines a Z-line adjacent structure common to all myofibers, whereas the second Tm defines a spatially distinct structure unique to muscles that undergo chronic or repetitive contractions. When a Tm (Tm3) that is normally absent from muscle was expressed in mice it became associated with the Z-line adjacent structure. These mice display a muscular dystrophy and ragged-red fiber phenotype, suggestive of disruption of the membrane-associated cytoskeletal network. Our findings raise the possibility that mutations in these tropomyosin and these structures may underpin these types of myopathies.
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MESH Headings
- Animals
- Cell Compartmentation/genetics
- Cell Membrane/metabolism
- Cell Membrane/pathology
- Cell Membrane/ultrastructure
- Cytoskeleton/metabolism
- Cytoskeleton/pathology
- Cytoskeleton/ultrastructure
- Disease Models, Animal
- Female
- Mice
- Mice, Transgenic
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscle Fibers, Skeletal/ultrastructure
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscle, Skeletal/ultrastructure
- Muscular Dystrophy, Animal/etiology
- Muscular Dystrophy, Animal/metabolism
- Muscular Dystrophy, Animal/physiopathology
- Mutation/genetics
- Phenotype
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Protein Isoforms/ultrastructure
- Protein Transport/genetics
- Sarcomeres/metabolism
- Sarcomeres/pathology
- Sarcomeres/ultrastructure
- Tropomyosin/genetics
- Tropomyosin/metabolism
- Tropomyosin/ultrastructure
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Affiliation(s)
- Anthony J Kee
- Muscle Development Unit, Children's Medical Research Institute, Locked Bag 23, Wentworthville, New South Wales 2145, Australia
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42
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Menez J, Le Maux Chansac B, Dorothée G, Vergnon I, Jalil A, Carlier MF, Chouaib S, Mami-Chouaib F. Mutant α-actinin-4 promotes tumorigenicity and regulates cell motility of a human lung carcinoma. Oncogene 2004; 23:2630-9. [PMID: 15048094 DOI: 10.1038/sj.onc.1207347] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The precise role of alpha-actinin-4 encoding gene (ACTN4) is not very well understood. It has been reported to elicit tumor suppressor activity and to regulate cellular motility. To further assess the function of human ACTN4, we studied a lung carcinoma cell line expressing a mutated alpha-actinin-4, which is recognized as a tumor antigen by autologous CD8(+) cytotoxic T lymphocytes (CTL). Confocal immunofluorescence microscopy indicated that, while wild-type (WT) alpha-actinin-4 stains into actin cytoskeleton and cell surface ruffles, the mutated protein is only dispersed in the cytoplasm of the lung carcinoma cells. This loss of association with the cell surface did not appear to correlate with a decrease in in vitro alpha-actinin-4 crosslinking to filamentous (F)-actin. Interestingly, experiments using cell lines stably expressing ACTN4 demonstrated that as opposed to WT gene, mutant ACTN4 was unable to inhibit tumor cell growth in vitro and in vivo. Moreover, the expression of mutant alpha-actinin-4 resulted in the loss of tumor cell capacity to migrate. The identification of an inactivating mutation in ACTN4 emphasizes its role as a tumor suppressor gene and underlines the involvement of cytoskeleton alteration in tumor development and metastasis.
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Affiliation(s)
- Jeanne Menez
- Laboratoire Cytokines et Immunologie des tumeurs Humaines, U487 INSERM, Institut Fédératif de Recherche 54, Institut Gustave Roussy, F-94805 Villejuif Cedex, France
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43
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Hook J, Lemckert F, Qin H, Schevzov G, Gunning P. Gamma tropomyosin gene products are required for embryonic development. Mol Cell Biol 2004; 24:2318-23. [PMID: 14993271 PMCID: PMC355842 DOI: 10.1128/mcb.24.6.2318-2323.2004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Accepted: 11/12/2003] [Indexed: 11/20/2022] Open
Abstract
The actin filament system is essential for many cellular functions, including shape, motility, cytokinesis, intracellular trafficking, and tissue organization. Tropomyosins (Tms) are rod-like components of most actin filaments that differentially affect their stability and flexibility. The Tm gene family consists of four genes, alphaTm, betaTm, gammaTm (Tm5 NM, where "NM" indicates "nonmuscle"), and deltaTm (Tm4). Multiple isoforms of the Tm family are generated by alternative splicing of three of these genes, and their expression is highly regulated. Extensive spatial and temporal sorting of Tm isoforms into different cellular compartments has been shown to occur in several cell types. We have addressed the function of the low-molecular-weight Tms encoded by the gammaTm gene by eliminating the corresponding amino-terminal coding sequences from this gene. Heterozygous mice were generated, and subsequent intercrossing of the F1 pups did not result in any viable homozygous knockouts. Genotype analysis of day 2.5 morulae also failed to detect any homozygous knockouts. We have failed in our attempts to delete the second allele and generate in vitro double-knockout cells, although 51 clones displayed homologous recombination back into the originally targeted locus. We therefore conclude that low-molecular-weight products from the gammaTm gene are essential for both embryonic development and cell survival.
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Affiliation(s)
- J Hook
- Oncology Research Unit, The Children's Hospital at Westmead, Westmead, New South Wales 2145, Australia
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44
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Yager ML, Hughes JAI, Lovicu FJ, Gunning PW, Weinberger RP, O'Neill GM. Functional analysis of the actin-binding protein, tropomyosin 1, in neuroblastoma. Br J Cancer 2003; 89:860-3. [PMID: 12942118 PMCID: PMC2394486 DOI: 10.1038/sj.bjc.6601201] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Tropomyosin 1 (TM1) is downregulated in a number of transformed cell types, and exogenous expression of TM1 can restore actin organisation and reverse cellular transformation. We find that TM1 is also downregulated in human neuroblastoma cell lines, correlating with increasing malignancy. However, exogenous TM1 does not restore actin cytoskeleton organisation in neuroblastoma cells.
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Affiliation(s)
- M L Yager
- The Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead 2145, NSW, Australia
- Department of Anatomy and Histology, The University of Sydney, Sydney 2000, NSW, Australia
| | - J A I Hughes
- The Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead 2145, NSW, Australia
- Discipline of Paediatrics and Child Health, Faculty of Medicine, The University of Sydney, Sydney, NSW, Australia
| | - F J Lovicu
- Department of Anatomy and Histology, The University of Sydney, Sydney 2000, NSW, Australia
| | - P W Gunning
- The Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead 2145, NSW, Australia
- Discipline of Paediatrics and Child Health, Faculty of Medicine, The University of Sydney, Sydney, NSW, Australia
| | - R P Weinberger
- The Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead 2145, NSW, Australia
- Discipline of Paediatrics and Child Health, Faculty of Medicine, The University of Sydney, Sydney, NSW, Australia
| | - G M O'Neill
- The Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead 2145, NSW, Australia
- Discipline of Paediatrics and Child Health, Faculty of Medicine, The University of Sydney, Sydney, NSW, Australia
- The Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead 2145, NSW, Australia. E-mail:
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45
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Orend G, Huang W, Olayioye MA, Hynes NE, Chiquet-Ehrismann R. Tenascin-C blocks cell-cycle progression of anchorage-dependent fibroblasts on fibronectin through inhibition of syndecan-4. Oncogene 2003; 22:3917-26. [PMID: 12813465 DOI: 10.1038/sj.onc.1206618] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tenascin-C is an adhesion-modulatory extracellular matrix protein that is predominantly expressed during embryonic development, wound healing and in tumor stroma. Here we report that anchorage-dependent human, rat and mouse fibroblasts adhere poorly and fail to proliferate on pure tenascin-C. This was due to a significant reduction of cyclin-dependent kinase 2 (cdk2) activity, resulting from elevated expression and association of the cdk inhibitors (CKIs) p21Cip1 and p27Kip1. To analyse the effect of tenascin-C on fibronectin-mediated adhesion, cells were plated on a mixed fibronectin/tenascin-C substratum. Compared to fibronectin alone, cell spreading and adhesion signaling were compromised, as determined by delayed phosphorylation kinetics of focal adhesion kinase (FAK). Despite the presence of growth factors, these cells remained arrested in the G1 phase of the cell cycle. In contrast to cells plated on pure tenascin-C, cdk2 activity appeared to be inhibited independently of CKIs. Interestingly, overexpression of the transmembrane proteoglycan syndecan-4 restored cell spreading, adhesion signaling and DNA replication on the fibronectin/tenascin-C substratum. A similar rescue was observed using a recombinant peptide that spans the syndecan-4-binding site in fibronectin. This indicates that tenascin-C causes cell cycle arrest and cdk2 inactivation by interfering with fibronectin-syndecan-4 interactions. We therefore propose that syndecan-4 signaling plays a central role in the control of cellular proliferation of anchorage-dependent fibroblasts.
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Affiliation(s)
- Gertraud Orend
- Friedrich Miescher Institute for Biomedical Research, Novartis Forschungsstiftung, PO Box 2543, CH-4002 Basel, Switzerland.
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46
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Janssen RAJ, Kim PN, Mier JW, Morrison DK. Overexpression of kinase suppressor of Ras upregulates the high-molecular-weight tropomyosin isoforms in ras-transformed NIH 3T3 fibroblasts. Mol Cell Biol 2003; 23:1786-97. [PMID: 12588996 PMCID: PMC151698 DOI: 10.1128/mcb.23.5.1786-1797.2003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2002] [Revised: 10/10/2002] [Accepted: 12/12/2002] [Indexed: 01/08/2023] Open
Abstract
The down-regulation of the high-molecular-weight isoforms of tropomyosin (TM) is considered to be an essential event in cellular transformation. In ras-transformed fibroblasts, the suppression of TM is dependent on the activity of the Raf-1 kinase; however, the requirement for other downstream effectors of Ras, such as MEK and ERK, is less clear. In this study, we have utilized the mitogen-activated protein kinase scaffolding protein Kinase Suppressor of Ras (KSR) to further investigate the regulation of TM and to clarify the importance of MEK/ERK signaling in this process. Here, we report that overexpression of wild-type KSR1 in ras-transformed fibroblasts restores TM expression and induces cell flattening and stress fiber formation. Moreover, we find that the transcriptional activity of a TM-alpha promoter is decreased in ras-transformed cells and that the restoration of TM by KSR1 coincides with increased transcription from this promoter. Although ERK activity was suppressed in cells overexpressing KSR1, ERK inhibition alone was insufficient to upregulate TM expression. The KSR1-mediated effects on stress fiber formation and TM transcription required the activity of the ROCK kinase, because these effects could be suppressed by the ROCK inhibitor, Y27632. Overexpression of KSR1 did not directly regulate ROCK activity, but did permit the recoupling of ROCK to the actin polymerization machinery. Finally, all of the KSR1-induced effects were mediated by the C-terminal domain of KSR1 and were dependent on the KSR-MEK interaction.
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Affiliation(s)
- Richard A J Janssen
- Regulation of Cell Growth Laboratory, National Cancer Institute-Frederick, Frederick, Maryland 21702, USA.
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47
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Breen EC, Tang K. Calcyclin (S100A6) regulates pulmonary fibroblast proliferation, morphology, and cytoskeletal organization in vitro. J Cell Biochem 2003; 88:848-54. [PMID: 12577318 DOI: 10.1002/jcb.10398] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Calcyclin (S100A6) is a member of the S100A family of calcium binding proteins. While the precise function of calcyclin is unknown, calcyclin expression is associated with cell proliferation and calcyclin is expressed in several types of cancer phenotypes. In the present study, the functional role of calcyclin was further elucidated in pulmonary fibroblasts. Antisense S100A6 RNA expression inhibited serum and mechanical strain-induced fibroblast proliferation. This attenuated proliferative response was accompanied by a flattened, spread cell morphology, and disruption of tropomyosin labeled microfilaments. Changes in cytoskeletal organization did not correspond with a decrease in tropomyosin levels. These observations suggest a role for calcyclin in modulating calcium dependent signaling events that regulate progression through the cell cycle. J. Cell. Biochem. 88: 848-854, 2003.
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Affiliation(s)
- Ellen C Breen
- Division of Physiology, Department of Medicine, University of California, San Diego, La Jolla, California, USA.
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48
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Abstract
Carcinogenesis - the process of cancer formation - is commonly discussed in terms of genetic alterations that lead to deregulation of cell growth. Recently, there has been a resurgence of interest in epigenetic factors and, in particular, the role of the stromal microenvironment and angiogenesis in tumor formation. In this article, cancer is presented as a disease of the developmental processes that govern how cells organize into tissues and tissues into organs. This histogenetic perspective raises the possibility that epithelial-mesenchymal interactions and the extracellular matrix (basement membrane) that is deposited through these interactions may actively contribute to the carcinogenic process. Experimental work is reviewed that confirms that extracellular matrix plays a key role in normal histodifferentiation during both epitheliogenesis and angiogenesis, and that epigenetic deregulation of cell-matrix interactions may actively promote tumor initiation and progression. The contributions of integrins, cytoskeleton, tensegrity and local variations in extracellular matrix mechanics to these processes are discussed, as are the implications of this work for future studies on cancer formation.
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Affiliation(s)
- Donald E Ingber
- Department of Pathology and Surgery, Harvard Medical School and Children's Hospital, Boston, MA 02115, USA.
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49
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Spinner BJ, Zajdel RW, McLean MD, Denz CR, Dube S, Mehta S, Choudhury A, Nakatsugawa M, Dobbins N, Lemanski LF, Dube DK. Characterization of a TM-4 type tropomyosin that is essential for myofibrillogenesis and contractile activity in embryonic hearts of the Mexican axolotl. J Cell Biochem 2002; 85:747-61. [PMID: 11968015 DOI: 10.1002/jcb.10178] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A striated muscle isoform of a Tropomyosin (TM-4) gene was characterized and found to be necessary for contractile function in embryonic heart. The full-length clone of this isoform was isolated from the Mexican axolotl (Ambystoma mexicanum) and named Axolotl Tropomyosin Cardiac-3 (ATmC-3). The gene encoded a cardiac-specific tropomyosin protein with 284 amino acid residues that demonstrated high homology to the Xenopus cardiac TM-4 type tropomyosin. Northern blot analysis indicates a transcript of approximately 1.25 kb in size. RT-PCR and in situ hybridization demonstrated that this isoform is predominantly in cardiac tissue. Our laboratory uses an animal model that carries a cardiac lethal mutation (gene c), this mutation results in a greatly diminished level of tropomyosin protein in the ventricle. Transfection of ATmC-3 DNA into mutant hearts increased tropomyosin levels and promoted myofibrillogenesis. ATmC-3 expression was blocked in normal hearts by transfection of exon-specific anti-sense oligonucleotide (AS-ODN). RT-PCR confirmed lower transcript expression of ATmC-3 and in vitro analysis confirmed the specificity of the ATmC-3 exon 2 anti-sense oligonucleotide. These AS-ODN treated hearts also had a disruption of myofibril organization and disruption of synchronous contractions. These results demonstrated that a striated muscle isoform of the TM-4 gene was expressed embryonically and was necessary for normal structure and function of the ventricle.
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Affiliation(s)
- Belinda J Spinner
- Department of Cell and Developmental Biology, Upstate Medical University, 750 East Adams Street, Syracuse, New York 13210, USA
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50
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Gordon SR. Microfilament disruption in a noncycling organized tissue, the corneal endothelium, initiates mitosis. Exp Cell Res 2002; 272:127-34. [PMID: 11777337 DOI: 10.1006/excr.2001.5407] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The adult corneal endothelium represents a noncycling cell population that resides as a monolayer on its basement membrane, Descemet's membrane. Evidence is presented for the first time, showing that mitotic regulation in this organized tissue, residing on its natural basement membrane, is coupled to microfilament integrity. When mitotically quiescent rat corneal endothelia are organ cultured in medium containing serum and cytochalasin B, low levels of mitosis are initiated. Supplementing the culture medium with either insulin or IGF-2 augments this response and results in increased cell density within the tissue monolayer. Fluorescence microscopy of actin using TRITC-conjugated phalloidin revealed that cellular circumferential microfilament bundles appear unaffected by cytochalasin B treatment, whereas the cytoplasmic microfilaments appear to be completely disrupted. These results suggest the possibility that the actin cytoskeleton is involved with the regulation of cell growth in the corneal endothelium.
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Affiliation(s)
- Sheldon R Gordon
- Department of Biological Sciences, Oakland University, Rochester, Michigan 48309-4476, USA.
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