1
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Actomyosin and the MRTF-SRF pathway downregulate FGFR1 in mesenchymal stromal cells. Commun Biol 2020; 3:576. [PMID: 33067523 PMCID: PMC7567845 DOI: 10.1038/s42003-020-01309-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 08/25/2020] [Indexed: 12/14/2022] Open
Abstract
Both biological and mechanical signals are known to influence cell proliferation. However, biological signals are mostly studied in two-dimensions (2D) and the interplay between these different pathways is largely unstudied. Here, we investigated the influence of the cell culture environment on the response to bFGF, a widely studied and important proliferation growth factor. We observed that human mesenchymal stromal cells (hMSCs), but not fibroblasts, lose the ability to respond to soluble or covalently bound bFGF when cultured on microfibrillar substrates. This behavior correlated with a downregulation of FGF receptor 1 (FGFR1) expression of hMSCs on microfibrillar substrates. Inhibition of actomyosin or the MRTF/SRF pathway decreased FGFR1 expression in hMSCs, fibroblasts and MG63 cells. To our knowledge, this is the first time FGFR1 expression is shown to be regulated through a mechanosensitive pathway in hMSCs. These results add to the sparse literature on FGFR1 regulation and potentially aid designing tissue engineering constructs that better control cell proliferation.
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2
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Dou Q, Hao F, Sun L, Xu X, Cui MZ. CRE and SRE mediate LPA-induced CCN1 transcription in mouse aortic smooth muscle cells. Can J Physiol Pharmacol 2016; 95:275-280. [PMID: 28157379 DOI: 10.1139/cjpp-2016-0559] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lysophosphatidic acid (LPA), one component of oxidized low-density lipoprotein (ox-LDL), is a potent bioactive phospholipid. Our recent data reveal that LPA induces matricellular protein CCN1 (also known as Cyr61) expression in aortic smooth muscle cells (SMCs) and that CCN1 bridges LPA and integrin signaling pathways leading to SMC migration. Whether and how LPA regulates the transcriptional machinery of the CCN1 gene are unknown. In this study, we found that LPA markedly induces CCN1 mRNA expression in SMCs. Using deleting mutation and reporter gene strategies, we demonstrated regions from -2038 to -1787 and from -101 to +63 of the CCN1 promoter contain the essential regulatory elements. The serum response element (SRE) and cyclic AMP-response element (CRE) are located in these regions. LPA induced time-dependent phosphorylation of serum response factor (SRF) and CRE-binding protein (CREB) in mouse SMCs. Luciferase assays of a series of deleted, mutated CCN1 promoter-reporter gene constructs and dominant negative construct revealed the distal SRE and the proximal CRE in the CCN1 promoter are required for LPA-induced CCN1 gene expression. Our results imply that elevated LPA levels may trigger SMC migration and exacerbate restenosis and atherosclerotic lesions through the induced CCN1, which communicates with a set of plasma membrane proteins and intracellular kinases.
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Affiliation(s)
- Quanlin Dou
- a Department of Biomedical & Diagnostic Sciences, University of Tennessee, Knoxville, Tennessee, USA.,b State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, China 810016
| | - Feng Hao
- a Department of Biomedical & Diagnostic Sciences, University of Tennessee, Knoxville, Tennessee, USA
| | - Longsheng Sun
- a Department of Biomedical & Diagnostic Sciences, University of Tennessee, Knoxville, Tennessee, USA.,c College of Animal Science and Technology, Yangzhou University, China 225009
| | - Xuemin Xu
- a Department of Biomedical & Diagnostic Sciences, University of Tennessee, Knoxville, Tennessee, USA
| | - Mei-Zhen Cui
- a Department of Biomedical & Diagnostic Sciences, University of Tennessee, Knoxville, Tennessee, USA
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3
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Yap LF, Lai SL, Patmanathan SN, Gokulan R, Robinson CM, White JB, Chai SJ, Rajadurai P, Prepageran N, Liew YT, Lopes V, Wei W, Hollows RJ, Murray PG, Lambert DW, Hunter KD, Paterson IC. HOPX functions as a tumour suppressor in head and neck cancer. Sci Rep 2016; 6:38758. [PMID: 27934959 PMCID: PMC5146930 DOI: 10.1038/srep38758] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 11/14/2016] [Indexed: 11/08/2022] Open
Abstract
Head and neck squamous cell carcinoma (HNSCC) is generalized term that encompasses a diverse group of cancers that includes tumours of the oral cavity (OSCC), oropharynx (OPSCC) and nasopharynx (NPC). Genetic alterations that are common to all HNSCC types are likely to be important for squamous carcinogenesis. In this study, we have investigated the role of the homeodomain-only homeobox gene, HOPX, in the pathogenesis of HNSCC. We show that HOPX mRNA levels are reduced in OSCC and NPC cell lines and tissues and there is a general reduction of HOPX protein expression in these tumours and OPSCCs. HOPX promoter methylation was observed in a subset of HNSCCs and was associated with a worse overall survival in HPV negative tumours. RNAseq analysis of OSCC cells transfected with HOPX revealed a widespread deregulation of the transcription of genes related to epithelial homeostasis and ectopic over-expression of HOPX in OSCC and NPC cells inhibited cell proliferation, plating efficiency and migration, and enhanced sensitivity to UVA-induced apoptosis. Our results demonstrate that HOPX functions as a tumour suppressor in HNSCC and suggest a central role for HOPX in suppressing epithelial carcinogenesis.
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Affiliation(s)
- Lee Fah Yap
- Department of Oral and Craniofacial Sciences and Oral Cancer Research and Coordinating Centre, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Sook Ling Lai
- Department of Oral and Craniofacial Sciences and Oral Cancer Research and Coordinating Centre, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Sathya Narayanan Patmanathan
- Department of Oral and Craniofacial Sciences and Oral Cancer Research and Coordinating Centre, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Ravindran Gokulan
- Department of Oral and Craniofacial Sciences and Oral Cancer Research and Coordinating Centre, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - C. Max Robinson
- Centre for Oral Health Research, Newcastle University, Newcastle, NE2 4BW, United Kingdom
| | - Joe B. White
- Unit of Oral and Maxillofacial Pathology, School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, Unite Kingdom
| | - San Jiun Chai
- Cancer Research Malaysia, Selangor, 47500 Subang Jaya, Malaysia
| | | | - Narayanan Prepageran
- Department of Otorhinolaryngology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Yew Toong Liew
- Department of Otorhinolaryngology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Victor Lopes
- Department of Oral surgery, Edinburgh Postgraduate Dental Institute, University of Edinburgh, Edinburgh, EH3 9HA, United Kingdom
| | - Wenbin Wei
- Institute of Cancer and Genomic Studies, University of Birmingham, Birmingham, B15 2TT, United Kingdom
- Sheffield Institute of Translational Neuroscience, University of Sheffield, Sheffield, S10 2HQ, United Kingdom
| | - Robert J. Hollows
- Institute of Cancer and Genomic Studies, University of Birmingham, Birmingham, B15 2TT, United Kingdom
| | - Paul G. Murray
- Institute of Cancer and Genomic Studies, University of Birmingham, Birmingham, B15 2TT, United Kingdom
| | - Daniel W. Lambert
- Unit of Oral and Maxillofacial Pathology, School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, Unite Kingdom
| | - Keith D. Hunter
- Unit of Oral and Maxillofacial Pathology, School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, Unite Kingdom
| | - Ian C. Paterson
- Department of Oral and Craniofacial Sciences and Oral Cancer Research and Coordinating Centre, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
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4
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Lee MY, Park C, Berent RM, Park PJ, Fuchs R, Syn H, Chin A, Townsend J, Benson CC, Redelman D, Shen TW, Park JK, Miano JM, Sanders KM, Ro S. Smooth Muscle Cell Genome Browser: Enabling the Identification of Novel Serum Response Factor Target Genes. PLoS One 2015; 10:e0133751. [PMID: 26241044 PMCID: PMC4524680 DOI: 10.1371/journal.pone.0133751] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 06/30/2015] [Indexed: 11/18/2022] Open
Abstract
Genome-scale expression data on the absolute numbers of gene isoforms offers essential clues in cellular functions and biological processes. Smooth muscle cells (SMCs) perform a unique contractile function through expression of specific genes controlled by serum response factor (SRF), a transcription factor that binds to DNA sites known as the CArG boxes. To identify SRF-regulated genes specifically expressed in SMCs, we isolated SMC populations from mouse small intestine and colon, obtained their transcriptomes, and constructed an interactive SMC genome and CArGome browser. To our knowledge, this is the first online resource that provides a comprehensive library of all genetic transcripts expressed in primary SMCs. The browser also serves as the first genome-wide map of SRF binding sites. The browser analysis revealed novel SMC-specific transcriptional variants and SRF target genes, which provided new and unique insights into the cellular and biological functions of the cells in gastrointestinal (GI) physiology. The SRF target genes in SMCs, which were discovered in silico, were confirmed by proteomic analysis of SMC-specific Srf knockout mice. Our genome browser offers a new perspective into the alternative expression of genes in the context of SRF binding sites in SMCs and provides a valuable reference for future functional studies.
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Affiliation(s)
- Moon Young Lee
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
- Department of Physiology, Wonkwang Digestive Disease Research Institute and Institute of Wonkwang Medical Science, School of Medicine, Wonkwang University, Iksan, Jeollabuk-do, Korea
| | - Chanjae Park
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Robyn M. Berent
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Paul J. Park
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Robert Fuchs
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Hannah Syn
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Albert Chin
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Jared Townsend
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Craig C. Benson
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Doug Redelman
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Tsai-wei Shen
- LC Sciences, 2575 West Bellfort Street Suite 270, Houston, Texas, United States of America
| | - Jong Kun Park
- Division of Biological Science, Wonkwang University, Iksan, Jeollabuk-do, South Korea
| | - Joseph M. Miano
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Kenton M. Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Seungil Ro
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
- * E-mail:
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Chen C, Wang Y, Yang S, Li H, Zhao G, Wang F, Yang L, Wang DW. MiR-320a contributes to atherogenesis by augmenting multiple risk factors and down-regulating SRF. J Cell Mol Med 2015; 19:970-85. [PMID: 25728840 PMCID: PMC4420600 DOI: 10.1111/jcmm.12483] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 10/07/2014] [Indexed: 01/29/2023] Open
Abstract
Atherosclerosis progress is regulated by a variety of factors. Here, we show that miR-320a, an intergenic miRNA, is markedly elevated in the peripheral blood of coronary heart disease patients and high-risk patients. Microarray analysis and qRT-PCR assays showed that circulating miRNA-320a was highly expressed in coronary artery disease patients. In vivo study showed that overexpression of miR-320a resulted in significant increase in levels of plasma lipid (total cholesterol, Triglyceride and low-density lipoprotein) and serum inflammatory cytokines (IL-6, MCP-1, sICAM, pSelectin, TNF-α and fibrinogen). In ApoE(-/-) mice, miR-320a expression attenuates endothelium cell function and promotes atherogenesis. Bioinformatics analysis identified serum response factor as a potential target for miR-320a, which was validated by luciferase reporter activity assay and western-blot in vitro and in vivo. Moreover, miR-320a expression inhibits human-derived endothelium cell proliferation and induces apoptosis. We also found that SP1 transcriptionally up-regulates hsa-miR-320a expression. Our observations indicate that miR-320a is a key regulator contributing to multiple aspects of atherogenesis.
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Affiliation(s)
- Chen Chen
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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6
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Brennan-Laun SE, Li XL, Ezelle HJ, Venkataraman T, Blackshear PJ, Wilson GM, Hassel BA. RNase L attenuates mitogen-stimulated gene expression via transcriptional and post-transcriptional mechanisms to limit the proliferative response. J Biol Chem 2014; 289:33629-43. [PMID: 25301952 DOI: 10.1074/jbc.m114.589556] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cellular response to mitogens is tightly regulated via transcriptional and post-transcriptional mechanisms to rapidly induce genes that promote proliferation and efficiently attenuate their expression to prevent malignant growth. RNase L is an endoribonuclease that mediates diverse antiproliferative activities, and tristetraprolin (TTP) is a mitogen-induced RNA-binding protein that directs the decay of proliferation-stimulatory mRNAs. In light of their roles as endogenous proliferative constraints, we examined the mechanisms and functional interactions of RNase L and TTP to attenuate a mitogenic response. Mitogen stimulation of RNase L-deficient cells significantly increased TTP transcription and the induction of other mitogen-induced mRNAs. This regulation corresponded with elevated expression of serum-response factor (SRF), a master regulator of mitogen-induced transcription. RNase L destabilized the SRF transcript and formed a complex with SRF mRNA in cells providing a mechanism by which RNase L down-regulates SRF-induced genes. TTP and RNase L proteins interacted in cells suggesting that RNase L is directed to cleave TTP-bound RNAs as a mechanism of substrate specificity. Consistent with their concerted function in RNA turnover, the absence of either RNase L or TTP stabilized SRF mRNA, and a subset of established TTP targets was also regulated by RNase L. RNase L deficiency enhanced mitogen-induced proliferation demonstrating its functional role in limiting the mitogenic response. Our findings support a model of feedback regulation in which RNase L and TTP target SRF mRNA and SRF-induced transcripts. Accordingly, meta-analysis revealed an enrichment of RNase L and TTP targets among SRF-regulated genes suggesting that the RNase L/TTP axis represents a viable target to inhibit SRF-driven proliferation in neoplastic diseases.
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Affiliation(s)
- Sarah E Brennan-Laun
- From the Marlene and Stewart Greenebaum Cancer Center, Departments of Microbiology and Immunology and
| | - Xiao-Ling Li
- the Genetics Branch, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Heather J Ezelle
- From the Marlene and Stewart Greenebaum Cancer Center, Departments of Microbiology and Immunology and the Research Services, Baltimore Veterans Affairs Medical Center, Baltimore, Maryland 21201, and
| | | | - Perry J Blackshear
- the Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
| | - Gerald M Wilson
- From the Marlene and Stewart Greenebaum Cancer Center, Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Bret A Hassel
- From the Marlene and Stewart Greenebaum Cancer Center, Departments of Microbiology and Immunology and the Research Services, Baltimore Veterans Affairs Medical Center, Baltimore, Maryland 21201, and
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7
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Schwartz B, Marks M, Wittler L, Werber M, Währisch S, Nordheim A, Herrmann BG, Grote P. SRF is essential for mesodermal cell migration during elongation of the embryonic body axis. Mech Dev 2014; 133:23-35. [PMID: 25020278 DOI: 10.1016/j.mod.2014.07.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 07/01/2014] [Accepted: 07/03/2014] [Indexed: 12/22/2022]
Abstract
Mesoderm formation in the mouse embryo initiates around E6.5 at the primitive streak and continues until the end of axis extension at E12.5. It requires the process of epithelial-to-mesenchymal transition (EMT), wherein cells detach from the epithelium, adopt mesenchymal cell morphology, and gain competence to migrate. It was shown previously that, prior to mesoderm formation, the transcription factor SRF (Serum Response Factor) is essential for the formation of the primitive streak. To elucidate the role of murine Srf in mesoderm formation during axis extension we conditionally inactivated Srf in nascent mesoderm using the T(s)::Cre driver mouse. Defects in mutant embryos became apparent at E8.75 in the heart and in the allantois. From E9.0 onwards body axis elongation was arrested. Using genome-wide expression analysis, combined with SRF occupancy data from ChIP-seq analysis, we identified a set of direct SRF target genes acting in posterior nascent mesoderm which are enriched for transcripts associated with migratory function. We further show that cell migration is impaired in Srf mutant embryos. Thus, the primary role for SRF in the nascent mesoderm during elongation of the embryonic body axis is the activation of a migratory program, which is a prerequisite for axis extension.
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Affiliation(s)
- Benedikt Schwartz
- Max Planck Institute for Molecular Genetics, Department of Developmental Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany; Free University Berlin, Dept. of Biology, Chemistry and Pharmacy, Takustrasse 3, 14195 Berlin, Germany
| | - Matthias Marks
- Max Planck Institute for Molecular Genetics, Department of Developmental Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Lars Wittler
- Max Planck Institute for Molecular Genetics, Department of Developmental Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Martin Werber
- Max Planck Institute for Molecular Genetics, Department of Developmental Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Sandra Währisch
- Max Planck Institute for Molecular Genetics, Department of Developmental Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Alfred Nordheim
- Department of Molecular Biology, Interfaculty Institute for Cell Biology, University of Tübingen, 72076 Tübingen, Germany
| | - Bernhard G Herrmann
- Max Planck Institute for Molecular Genetics, Department of Developmental Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Phillip Grote
- Max Planck Institute for Molecular Genetics, Department of Developmental Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany.
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8
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Xie L. MKL1/2 and ELK4 co-regulate distinct serum response factor (SRF) transcription programs in macrophages. BMC Genomics 2014; 15:301. [PMID: 24758171 PMCID: PMC4023608 DOI: 10.1186/1471-2164-15-301] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 04/14/2014] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Serum response factor (SRF) is a widely expressed transcription factor involved in multiple regulatory programs. It is believed that SRF can toggle between disparate programs of gene expression through association with different cofactors. However, the direct evidence as to how these factors function on a genome-wide level is still lacking. RESULTS In the present study, I explored the functions of SRF and its representative cofactors, megakaryoblastic leukemia 1/2 (MKL1/2) and ETS-domain protein 4 (ELK4), during fungal infection challenge in macrophages. The knockdown study, combined with gene expression array analysis, revealed that MKL1/2 regulated SRF-dependent genes were related to actin cytoskeleton organization, while ELK4 regulated SRF-dependent genes were related to external stimulus responses. Subsequent chromatin immunoprecipitation coupled with massively parallel sequencing (ChIP-seq) suggested that many of these regulations were mediated directly in cis. CONCLUSIONS I conclude that SRF utilizes MKL1/2 to fulfill steady state cellular functions, including cytoskeletal organization, and utilizes ELK4 to facilitate acute responses to external infection. Together, these findings indicate that SRF, along with its two cofactors, are important players in both cellular homeostasis and stress responses in macrophages.
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Affiliation(s)
- Lan Xie
- Medical Systems Biology Research Center, Department of Biomedical Engineering, Tsinghua University School of Medicine, Beijing 100084, China.
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9
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David M, Machuca-Gayet I, Kikuta J, Ottewell P, Mima F, Leblanc R, Bonnelye E, Ribeiro J, Holen I, Vales RL, Jurdic P, Chun J, Clézardin P, Ishii M, Peyruchaud O. Lysophosphatidic acid receptor type 1 (LPA1) plays a functional role in osteoclast differentiation and bone resorption activity. J Biol Chem 2014; 289:6551-6564. [PMID: 24429286 DOI: 10.1074/jbc.m113.533232] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lysophosphatidic acid (LPA) is a natural bioactive lipid that acts through six different G protein-coupled receptors (LPA1-6) with pleiotropic activities on multiple cell types. We have previously demonstrated that LPA is necessary for successful in vitro osteoclastogenesis of bone marrow cells. Bone cells controlling bone remodeling (i.e. osteoblasts, osteoclasts, and osteocytes) express LPA1, but delineating the role of this receptor in bone remodeling is still pending. Despite Lpar1(-/-) mice displaying a low bone mass phenotype, we demonstrated that bone marrow cell-induced osteoclastogenesis was reduced in Lpar1(-/-) mice but not in Lpar2(-/-) and Lpar3(-/-) animals. Expression of LPA1 was up-regulated during osteoclastogenesis, and LPA1 antagonists (Ki16425, Debio0719, and VPC12249) inhibited osteoclast differentiation. Blocking LPA1 activity with Ki16425 inhibited expression of nuclear factor of activated T-cell cytoplasmic 1 (NFATc1) and dendritic cell-specific transmembrane protein and interfered with the fusion but not the proliferation of osteoclast precursors. Similar to wild type osteoclasts treated with Ki16425, mature Lpar1(-/-) osteoclasts had reduced podosome belt and sealing zone resulting in reduced mineralized matrix resorption. Additionally, LPA1 expression markedly increased in the bone of ovariectomized mice, which was blocked by bisphosphonate treatment. Conversely, systemic treatment with Debio0719 prevented ovariectomy-induced cancellous bone loss. Moreover, intravital multiphoton microscopy revealed that Debio0719 reduced the retention of CX3CR1-EGFP(+) osteoclast precursors in bone by increasing their mobility in the bone marrow cavity. Overall, our results demonstrate that LPA1 is essential for in vitro and in vivo osteoclast activities. Therefore, LPA1 emerges as a new target for the treatment of diseases associated with excess bone loss.
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Affiliation(s)
- Marion David
- INSERM, UMR1033, UCB Lyon 1, Faculté de Médecine Lyon Est, 69732 Lyon, France
| | - Irma Machuca-Gayet
- CNRS, UMR5242, ENS, Équipe Biologie Cellulaire et Physiopathologie Osseuse, Institut de Génomique Fonctionnelle de Lyon, UCB Lyon 1, 69007 Lyon, France
| | - Junichi Kikuta
- Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, 565-0871 Osaka, Japan; CREST, Japan Science and Technology Agency, 102-0076 Tokyo, Japan
| | - Penelope Ottewell
- Academic Unit of Clinical Oncology, University of Sheffield Medical School, Beech Hill Road, S10 2RX Sheffield, United Kingdom
| | - Fuka Mima
- Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, 565-0871 Osaka, Japan; CREST, Japan Science and Technology Agency, 102-0076 Tokyo, Japan
| | - Raphael Leblanc
- INSERM, UMR1033, UCB Lyon 1, Faculté de Médecine Lyon Est, 69732 Lyon, France
| | - Edith Bonnelye
- INSERM, UMR1033, UCB Lyon 1, Faculté de Médecine Lyon Est, 69732 Lyon, France
| | - Johnny Ribeiro
- INSERM, UMR1033, UCB Lyon 1, Faculté de Médecine Lyon Est, 69732 Lyon, France
| | - Ingunn Holen
- Academic Unit of Clinical Oncology, University of Sheffield Medical School, Beech Hill Road, S10 2RX Sheffield, United Kingdom
| | - Rùben Lopez Vales
- Grup de Neuroplasticitat i Regeneració, Unitat de Fisiologia Mèdica, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Pierre Jurdic
- CNRS, UMR5242, ENS, Équipe Biologie Cellulaire et Physiopathologie Osseuse, Institut de Génomique Fonctionnelle de Lyon, UCB Lyon 1, 69007 Lyon, France
| | - Jerold Chun
- Department of Molecular Biology, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, California 92037
| | - Philippe Clézardin
- INSERM, UMR1033, UCB Lyon 1, Faculté de Médecine Lyon Est, 69732 Lyon, France
| | - Masaru Ishii
- Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, 565-0871 Osaka, Japan; CREST, Japan Science and Technology Agency, 102-0076 Tokyo, Japan
| | - Olivier Peyruchaud
- INSERM, UMR1033, UCB Lyon 1, Faculté de Médecine Lyon Est, 69732 Lyon, France.
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10
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Saupe F, Schwenzer A, Jia Y, Gasser I, Spenlé C, Langlois B, Kammerer M, Lefebvre O, Hlushchuk R, Rupp T, Marko M, van der Heyden M, Cremel G, Arnold C, Klein A, Simon-Assmann P, Djonov V, Neuville-Méchine A, Esposito I, Slotta-Huspenina J, Janssen KP, de Wever O, Christofori G, Hussenet T, Orend G. Tenascin-C downregulates wnt inhibitor dickkopf-1, promoting tumorigenesis in a neuroendocrine tumor model. Cell Rep 2013; 5:482-92. [PMID: 24139798 DOI: 10.1016/j.celrep.2013.09.014] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 08/07/2013] [Accepted: 09/10/2013] [Indexed: 02/08/2023] Open
Abstract
The extracellular matrix molecule tenascin-C (TNC) is a major component of the cancer-specific matrix, and high TNC expression is linked to poor prognosis in several cancers. To provide a comprehensive understanding of TNC's functions in cancer, we established an immune-competent transgenic mouse model of pancreatic β-cell carcinogenesis with varying levels of TNC expression and compared stochastic neuroendocrine tumor formation in abundance or absence of TNC. We show that TNC promotes tumor cell survival, the angiogenic switch, more and leaky vessels, carcinoma progression, and lung micrometastasis. TNC downregulates Dickkopf-1 (DKK1) promoter activity through the blocking of actin stress fiber formation, activates Wnt signaling, and induces Wnt target genes in tumor and endothelial cells. Our results implicate DKK1 downregulation as an important mechanism underlying TNC-enhanced tumor progression through the provision of a proangiogenic tumor microenvironment.
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Affiliation(s)
- Falk Saupe
- Inserm U1109, MN3T Team, The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
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11
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Banning A, Ockenga W, Finger F, Siebrasse P, Tikkanen R. Transcriptional regulation of flotillins by the extracellularly regulated kinases and retinoid X receptor complexes. PLoS One 2012; 7:e45514. [PMID: 23029064 PMCID: PMC3445523 DOI: 10.1371/journal.pone.0045514] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 08/21/2012] [Indexed: 11/25/2022] Open
Abstract
Flotillin-1 and flotillin-2 are important regulators of signal transduction pathways such as growth factor signaling. Flotillin expression is increased under pathological conditions such as neurodegenerative disorders and cancer. Despite their importance for signal transduction, very little is known about the transcriptional regulation of flotillins. Here, we analyzed the expression of flotillins at transcriptional level and identified flotillins as downstream targets of the mitogen activated kinases ERK1/2. The promoter activity of flotillins was increased upon growth factor stimulation in a MAPK dependent manner. Overexpression of serum response factor or early growth response gene 1 resulted in increased flotillin mRNA and protein expression. Furthermore, both promoter activity and expression of endogenous flotillins were increased upon treatment with retinoic acid or by overexpression of the retinoid X receptor and its binding partners RARα and PPARγ. Our data indicate that the expression of flotillins, which can be detected in all cultured cells, is fine-tuned in response to various external stimuli. This regulation may be critical for the outcome of signaling cascades in which flotillins are known to be involved.
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Affiliation(s)
- Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
| | - Wymke Ockenga
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
| | - Fabian Finger
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
| | - Philipp Siebrasse
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
- * E-mail:
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12
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Sandbo N, Lau A, Kach J, Ngam C, Yau D, Dulin NO. Delayed stress fiber formation mediates pulmonary myofibroblast differentiation in response to TGF-β. Am J Physiol Lung Cell Mol Physiol 2011; 301:L656-66. [PMID: 21856814 DOI: 10.1152/ajplung.00166.2011] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Myofibroblast differentiation induced by transforming growth factor-β (TGF-β) and characterized by de novo expression of smooth muscle (SM)-specific proteins is a key process in wound healing and in the pathogenesis of fibrosis. We have previously shown that TGF-β-induced expression and activation of serum response factor (SRF) is required for this process. In this study, we examined the signaling mechanism for SRF activation by TGF-β as it relates to pulmonary myofibroblast differentiation. TGF-β stimulated a profound, but delayed (18-24 h), activation of Rho kinase and formation of actin stress fibers, which paralleled SM α-actin expression. The translational inhibitor cycloheximide blocked these processes without affecting Smad-dependent gene transcription. Inhibition of Rho kinase by Y-27632 or depolymerization of actin by latrunculin B resulted in inhibition TGF-β-induced SRF activation and SM α-actin expression, having no effect on Smad signaling. Conversely, stabilization of actin stress fibers by jasplakinolide was sufficient to drive these processes in the absence of TGF-β. TGF-β promoted a delayed nuclear accumulation of the SRF coactivator megakaryoblastic leukemia-1 (MKL1)/myocardin-related transcription factor-A, which was inhibited by latrunculin B. Furthermore, TGF-β also induced MKL1 expression, which was inhibited by latrunculin B, by SRF inhibitor CCG-1423, or by SRF knockdown. Together, these data suggest a triphasic model for myofibroblast differentiation in response to TGF-β that involves 1) initial Smad-dependent expression of intermediate signaling molecules driving Rho activation and stress fiber formation, 2) nuclear accumulation of MKL1 and activation of SRF as a result of actin polymerization, and 3) SRF-dependent expression of MKL1, driving further myofibroblast differentiation.
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Affiliation(s)
- Nathan Sandbo
- Univ. of Wisconsin School of Medicine and Public Health, 5229 MFCB 1685 Highland Ave, Madison, WI 53705, USA.
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13
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Burger LL, Haisenleder DJ, Marshall JC. GnRH pulse frequency differentially regulates steroidogenic factor 1 (SF1), dosage-sensitive sex reversal-AHC critical region on the X chromosome gene 1 (DAX1), and serum response factor (SRF): potential mechanism for GnRH pulse frequency regulation of LH beta transcription in the rat. Endocrine 2011; 39:212-9. [PMID: 21409515 DOI: 10.1007/s12020-011-9440-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 01/30/2011] [Indexed: 10/18/2022]
Abstract
The issue of how rapid frequency GnRH pulses selectively stimulate LH transcription is not fully understood. The rat LHβ promoter contains two GnRH-responsive regions: the proximal region has binding elements for SF1, and the distal site contains a CArG box, which binds SRF. This study determined whether GnRH stimulates pituitary SF1, DAX1 (an endogenous SF1 inhibitor), and SRF transcription in vivo, and whether regulation is frequency dependent. Male rats were pulsed with 25 ng GnRH i.v. every 30 min or every 240 min for 1-24 h, and primary transcripts (PTs) and mRNAs were measured by real time PCR. Fast frequency GnRH pulses (every 30 min) increased SF1 PT (threefold) within 1 h, and then declined after 6 h. SF1 mRNA also increased within 1 h and remained elevated through 24 h. Fast frequency GnRH also stimulated a transient increase in DAX1 PT (twofold after 1 h) and mRNA (1.7-fold after 6 h), while SRF mRNA rose briefly at 1 h. Slow frequency pulses did not affect gene expression of SF1, DAX1, or SRF. These findings support a mechanistic link between SF1 in the frequency regulation of LHβ transcription by pulsatile GnRH.
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Affiliation(s)
- Laura L Burger
- University of Michigan, Medical Sciences Building II, Ann Arbor, MI 48109, USA.
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14
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Sandbo N, Kregel S, Taurin S, Bhorade S, Dulin NO. Critical role of serum response factor in pulmonary myofibroblast differentiation induced by TGF-beta. Am J Respir Cell Mol Biol 2009; 41:332-8. [PMID: 19151320 DOI: 10.1165/rcmb.2008-0288oc] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Transforming growth factor-beta (TGF-beta) is a cytokine implicated in wound healing and in the pathogenesis of pulmonary fibrosis. TGF-beta stimulates myofibroblast differentiation characterized by expression of contractile smooth muscle (SM)-specific proteins such as SM-alpha-actin. In the present study, we examined the role of serum response factor (SRF) in the mechanism of TGF-beta-induced pulmonary myofibroblast differentiation of human lung fibroblasts (HLF). TGF-beta stimulated SM-alpha-actin expression in HLF, which paralleled with a profound induction of SRF expression and activity. Inhibition of SRF by the pharmacologic SRF inhibitor (CCG-1423), or via adenovirus-mediated transduction of SRF short hairpin RNA (shSRF), blocked the expression of both SRF and SM-alpha-actin in response to TGF-beta without affecting Smad-mediated signaling of TGF-beta. However, forced expression of SRF on its own did not promote SM-alpha-actin expression, whereas expression of the constitutively transactivated SRF fusion protein (SRF-VP16) was sufficient to induce SM-alpha-actin expression, suggesting that both expression and transactivation of SRF are important. Activation of protein kinase A (PKA) by forskolin or iloprost resulted in a significant inhibition of SM-alpha-actin expression induced by TGF-beta, and this was associated with inhibition of both SRF expression and activity, but not of Smad-mediated gene transcription. In summary, this is the first direct demonstration that TGF-beta-induced pulmonary myofibroblast differentiation is mediated by SRF, and that inhibition of myofibroblast differentiation by PKA occurs through down-regulation of SRF expression levels and SRF activity, independent of Smad signaling.
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Affiliation(s)
- Nathan Sandbo
- Section of Pulmonary and Critical Care Medicine, University of Chicago, 5841 S. Maryland Ave., MC 6076, Chicago, IL 60618, USA.
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15
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Lee J, Hwang J, Kim HS, Kim S, Kim YH, Park SY, Kim KS, Ryoo ZY, Chang KT, Lee S. A comparison of gene expression profiles between primary human AML cells and AML cell line. Genes Genet Syst 2008; 83:339-45. [PMID: 18931459 DOI: 10.1266/ggs.83.339] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In acute myeloid leukemia (AML), hematologic malignancies are characterized by recurring chromosomal abnormalities. Chromosome translocation t(9;11)(p22;q23) is one of the most common genetic aberrations and results in the formation of the MLL-AF9 fusion gene that functions as a facilitator of cell growth directly. In order to study this type of AML, the cell lines with cytogenetically diagnosed t(9;11)(p22;q23), such as Mono Mac 6 (MM6), have been widely used. To examine whether there is any difference in gene expression between the primary human t(9;11) AML cells and MM6 cell line, genome-wide transcriptome analysis was performed on MM6 cell line using SAGE and the results were compared to the profile of primary human t(9;11) AML cells. 884 transcripts which were alternatively expressed between MM6 cells and primary human t(9;11) cells were identified through statistical analysis (P < 0.05) and 4-fold expression change. Of these transcripts, 830 (94%) matched to known genes or EST were classified by functional categories (http://david.abcc.ncifcrf.gov/). The majority of alternatively expressed genes in MM6 were involved in biosynthetic and metabolic processes, but HRAS, a protein that is known to be associated with leukemogenesis, was expressed only in MM6 cells and several other genes involved in Erk1/Erk2 MAPK pathway were also over-expressed in MM6. Therefore, since MM6 cell line has a similar expression profile to primary human t(9;11) AML in general and expresses uniquely a strong Erk1/Erk2 MAPK pathway including HRAS, it can be used as a model for HRAS-positive t(9;11) AML.
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Affiliation(s)
- Jinseok Lee
- School of Life Science and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
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16
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Zhang J, Jia Z, Li Q, Wang L, Rashid A, Zhu Z, Evans DB, Vauthey JN, Xie K, Yao JC. Elevated expression of vascular endothelial growth factor correlates with increased angiogenesis and decreased progression-free survival among patients with low-grade neuroendocrine tumors. Cancer 2007; 109:1478-86. [PMID: 17340592 DOI: 10.1002/cncr.22554] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Vascular endothelial growth factor (VEGF) is a critical proangiogenic factor in solid tumors. However, its expression and role in human neuroendocrine tumor development and progression remains unclear. METHODS Using immunohistochemistry, VEGF and Sp1 expression patterns were investigated in 50 cases of human gastrointestinal neuroendocrine tumor having various clinicopathologic characteristics. RESULTS It was found that strong VEGF expression was detected in tumor cells, whereas no or very weak VEGF expression was detected in stromal cells surrounding or within the tumors. The levels of VEGF expression directly correlated with the expression levels of Sp1 and microvessel density. Strong, weak, and negative VEGF expression was observed in 32%, 54%, and 14% of cases, respectively. Compared with the group with negative VEGF expression, VEGF (weak/strong) expression was associated with metastasis (14% versus 58%; P = .03). The median progression-free survival (PFS) durations of patients with strong and weak VEGF expression were 29 months and 81 months, respectively. With a median follow-up duration of 50 months, the median PFS duration for the group with negative VEGF expression has not been reached. Compared with the log-rank test, VEGF expression was associated with poor PFS (P = .02). Using in vitro and in vivo models, human carcinoid cell lines were treated with bevacizumab, a monoclonal antibody targeting VEGF. Bevacizumab did not inhibit the growth of carcinoid cells in vitro but significantly reduced tumor angiogenesis and impaired tumor growth in animals. CONCLUSIONS The data suggest that overexpression of VEGF promotes the growth of human neuroendocrine tumors in part through up-regulation of angiogenesis.
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MESH Headings
- Angiogenesis Inhibitors/pharmacology
- Animals
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal, Humanized
- Bevacizumab
- Biomarkers, Tumor/analysis
- Blotting, Western
- Carcinoma, Neuroendocrine/blood supply
- Carcinoma, Neuroendocrine/metabolism
- Carcinoma, Neuroendocrine/mortality
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Disease-Free Survival
- Female
- Humans
- Immunohistochemistry
- Mice
- Mice, Nude
- Neovascularization, Pathologic/metabolism
- Prognosis
- Vascular Endothelial Growth Factor A/biosynthesis
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Affiliation(s)
- Jun Zhang
- Department of Gastrointestinal Medical Oncology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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17
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Posern G, Treisman R. Actin’ together: serum response factor, its cofactors and the link to signal transduction. Trends Cell Biol 2006; 16:588-96. [DOI: 10.1016/j.tcb.2006.09.008] [Citation(s) in RCA: 416] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 08/29/2006] [Accepted: 09/25/2006] [Indexed: 11/30/2022]
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18
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Cui MZ, Laag E, Sun L, Tan M, Zhao G, Xu X. Lysophosphatidic acid induces early growth response gene 1 expression in vascular smooth muscle cells: CRE and SRE mediate the transcription. Arterioscler Thromb Vasc Biol 2006; 26:1029-35. [PMID: 16497989 DOI: 10.1161/01.atv.0000214980.90567.b5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Lysophosphatidic acid (LPA), one component of oxidized low-density lipoprotein, is a potent bioactive phospholipid. Early growth response gene-1 (Egr-1), an important transcription factor, regulates expression of an array of genes involved in vascular diseases. Whether and how LPA regulates the transcriptional machinery of Egr-1 gene is unknown and is addressed in this study. METHOD AND RESULTS We found that LPA markedly induces Egr-1 mRNA and protein in aortic smooth muscle cells (SMCs). RNA stability and nuclear run-on assays reveal that LPA-induced Egr-1 gene expression is controlled at the transcriptional level. Reporter gene analyses have shown that the -141 to +20 nt region of the Egr-1 promoter contains regulatory elements. Electrophoretic mobility shift assays reveal that the DNA-binding activities of both CREB and SRF to the CRE and SRE motifs of the Egr-1 promoter are markedly elevated in response to LPA. The increased binding activity depends on the phosphorylation of CREB and SRF. Luciferase assays of a series of deleted or mutated Egr-1 promoter-reporter gene constructs, along with dominant negative CREB transfection analysis revealed that the 2 CRE sites and the 2 proximal SRE sites in the Egr-1 promoter are required for maximal LPA-induced Egr-1 gene expression. CONCLUSIONS Our data reveal that LPA regulates Egr-1 expression via transcription factors CREB and SRF. These results establish a novel role for CREB in mediating LPA-induced gene expression. Our results imply that elevated LPA levels may, through activation of Egr-1, which regulates an array of atherogenic genes, exacerbate atheromatous lesions.
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Affiliation(s)
- Mei-Zhen Cui
- Department of Pathobiology, The University of Tennessee, Knoxville, TN, USA.
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19
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Chen Y, Guo Y, Ge X, Itoh H, Watanabe A, Fujiwara T, Kodama T, Aburatani H. Elevated expression and potential roles of human Sp5, a member of Sp transcription factor family, in human cancers. Biochem Biophys Res Commun 2005; 340:758-66. [PMID: 16380080 DOI: 10.1016/j.bbrc.2005.12.068] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Accepted: 12/03/2005] [Indexed: 11/26/2022]
Abstract
In this report, we describe the expression and function of human Sp5, a member of the Sp family of zinc finger transcription factors. Like other family members, the Sp5 protein contains a Cys2His2 zinc finger DNA binding domain at the C-terminus. Our experiments employing Gal4-Sp5 fusion proteins reveal multiple transcriptional domains, including a N-terminal activity domain, an intrinsic repressive element, and a C-terminal synergistic domain. Elevated expression of Sp5 was noted in several human tumors including hepatocellular carcinoma, gastric cancer, and colon cancer. To study the effects of the Sp5 protein on growth properties of human cancer cells and facilitate the identification of its downstream genes, we combined an inducible gene expression system with microarray analysis to screen for its transcriptional targets. Transfer of Sp5 into MCF-7 cells that expressed no detectable endogenous Sp5 protein elicited significant growth promotion activity. Several of the constitutively deregulated genes have been associated with tumorigenesis (CDC25C, CEACAM6, TMPRSS2, XBP1, MYBL1, ABHD2, and CXCL12) and Wnt/beta-Catenin signaling pathways (BAMBI, SIX1, IGFBP5, AES, and p21WAF1). This information could be utilized for further mechanistic research and for devising optimized therapeutic strategies against human cancers.
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Affiliation(s)
- Yongxin Chen
- Genome Science Division, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Japan
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20
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MacLean JA, Rao MK, Doyle KMH, Richards JS, Wilkinson MF. Regulation of the Rhox5 Homeobox Gene in Primary Granulosa Cells: Preovulatory Expression and Dependence on SP1/SP3 and GABP1. Biol Reprod 2005; 73:1126-34. [PMID: 16093360 DOI: 10.1095/biolreprod.105.042747] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Homeobox genes encode transcription factors that regulate embryonic development and postnatal events. Rhox5 (previously called Pem), the founding member of a homeobox gene cluster that we recently identified on the X chromosome, is selectively expressed in granulosa cells in the ovary and other somatic-cell types in other reproductive organs. In this report, we investigate its regulation in granulosa cells in the rat ovary. We found that Rhox5 expression in the ovary is governed by the Rhox5 distal promoter and is expressed at least as early as Day 5 postpartum. Rhox5 mRNA levels are regulated during the ovarian cycle, peaking before ovulation. Deletion analysis revealed a 25-nt element essential for distal promoter transcription in primary granulosa cells. This distal promoter element contains two ETS and one SP1 transcription-factor family binding sites that mutagenesis analysis indicated were essential for high-level transcription. This element was both necessary and sufficient for transcription, because it activated transcription when placed upstream of a heterologous minimal promoter. Cold competition and electrophoretic mobility shift assay studies demonstrated that SP1, SP3, and the ETS family transcription factor GABP bound this element. Dominant-negative forms of GABP and SP3 repressed distal promoter expression in primary rat granulosa, showing that these factors are crucial for Rhox5 expression. Cotransfection of dominant-negative mutants indicated that Rhox5 expression in granulosa cells is regulated by the c-Jun N-terminal protein kinase (JNK, MAPK8) and RAS pathways, which are known to be upstream of ETS family transcription factors. The discovery that Rhox5 expression in granulosa cells is regulated by MAPK pathways and ETS and SP1 family members provides an opportunity to understand how these regulatory pathways and factors collaborate to regulate gene expression during the ovarian cycle.
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Affiliation(s)
- James A MacLean
- Department of Immunology, The University of Texas, M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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21
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Dieterich C, Grossmann S, Tanzer A, Röpcke S, Arndt PF, Stadler PF, Vingron M. Comparative promoter region analysis powered by CORG. BMC Genomics 2005; 6:24. [PMID: 15723697 PMCID: PMC555765 DOI: 10.1186/1471-2164-6-24] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Accepted: 02/21/2005] [Indexed: 11/10/2022] Open
Abstract
Background Promoters are key players in gene regulation. They receive signals from various sources (e.g. cell surface receptors) and control the level of transcription initiation, which largely determines gene expression. In vertebrates, transcription start sites and surrounding regulatory elements are often poorly defined. To support promoter analysis, we present CORG , a framework for studying upstream regions including untranslated exons (5' UTR). Description The automated annotation of promoter regions integrates information of two kinds. First, statistically significant cross-species conservation within upstream regions of orthologous genes is detected. Pairwise as well as multiple sequence comparisons are computed. Second, binding site descriptions (position-weight matrices) are employed to predict conserved regulatory elements with a novel approach. Assembled EST sequences and verified transcription start sites are incorporated to distinguish exonic from other sequences. As of now, we have included 5 species in our analysis pipeline (man, mouse, rat, fugu and zebrafish). We characterized promoter regions of 16,127 groups of orthologous genes. All data are presented in an intuitive way via our web site. Users are free to export data for single genes or access larger data sets via our DAS server . The benefits of our framework are exemplarily shown in the context of phylogenetic profiling of transcription factor binding sites and detection of microRNAs close to transcription start sites of our gene set. Conclusion The CORG platform is a versatile tool to support analyses of gene regulation in vertebrate promoter regions. Applications for CORG cover a broad range from studying evolution of DNA binding sites and promoter constitution to the discovery of new regulatory sequence elements (e.g. microRNAs and binding sites).
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Affiliation(s)
- Christoph Dieterich
- Computational Molecular Biology Department, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
| | - Steffen Grossmann
- Computational Molecular Biology Department, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
| | - Andrea Tanzer
- Institute for Theoretical Chemistry and Structural Biology, University of Vienna, Währingerstrasse 17, A-1090 Wien, Austria
- Bioinformatics Group, Department of Computer Science, University of Leipzig, Kreuzstraße 7b, D-04103 Leipzig, Germany
| | - Stefan Röpcke
- Computational Molecular Biology Department, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
| | - Peter F Arndt
- Computational Molecular Biology Department, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
| | - Peter F Stadler
- Institute for Theoretical Chemistry and Structural Biology, University of Vienna, Währingerstrasse 17, A-1090 Wien, Austria
- Bioinformatics Group, Department of Computer Science, University of Leipzig, Kreuzstraße 7b, D-04103 Leipzig, Germany
| | - Martin Vingron
- Computational Molecular Biology Department, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
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Bloomfield KL, Osborne SA, Kennedy DD, Clarke FM, Tonissen KF. Thioredoxin-mediated redox control of the transcription factor Sp1 and regulation of the thioredoxin gene promoter. Gene 2004; 319:107-16. [PMID: 14597176 DOI: 10.1016/s0378-1119(03)00799-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In recent years, redox control has emerged as a fundamental mechanism of gene regulation through transcriptional control. Thioredoxin (Trx) is a dithiol-reducing enzyme known to be involved in the redox regulation of a number of transcription factors, and in this study, we have investigated the redox-dependent regulation of the DNA binding activity of Sp1 by thioredoxin. Electrophoretic mobility shift assays were used to show that both recombinant Sp1 produced in Escherichia coli and endogenous Sp1 expressed by MDA-MB-231 breast cancer cells is subject to redox regulation. We found that thioredoxin alone or in conjunction with the full thioredoxin system (comprising thioredoxin, thioredoxin reductase [TR], and alpha-nicotinamide adenine dinucleotide phosphate [NADPH]) can increase Sp1 DNA binding activity in vitro to an oligonucleotide containing the Sp1 consensus sequence. Furthermore, we have provided evidence that recombinant Sp1 can bind to Sp1 consensus sequences within a 330-base pair (bp) thioredoxin promoter fragment and that this interaction can also be enhanced by the presence of thioredoxin. Luciferase reporter assays using this same minimal thioredoxin promoter region demonstrated that both Sp1 and Sp3 can bind to the promoter and act to enhance transcription. When the three identified Sp1 consensus sequences within the reporter construct were deleted, there was a loss of basal promoter activity, showing that these closely positioned sites are important for regulation of thioredoxin gene expression.
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Affiliation(s)
- Kelly L Bloomfield
- School of Biomolecular and Biomedical Science, Griffith University, Nathan, Qld, 4111, Australia.
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Zhang X, Azhar G, Furr MC, Zhong Y, Wei JY. Model of functional cardiac aging: young adult mice with mild overexpression of serum response factor. Am J Physiol Regul Integr Comp Physiol 2003; 285:R552-60. [PMID: 12909581 DOI: 10.1152/ajpregu.00631.2002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Serum response factor (SRF) is an important transcription factor that may have a role in the maintenance of cardiac structure and function. The level of SRF mRNA expression increases approximately 16% in the hearts of mice during adult aging. To model the effect of mild SRF elevation in the aging heart, transgenic mice with low levels of SRF overexpression were generated. By 6 mo of age, the transgenic mice had a 19% increase of heart-to-body weight ratio compared with nontransgenic mice. In addition, they had a 12% increase in myocyte size, a 6.7% increase in collagen deposition, and altered gene expression of a number of muscle-specific and cardiac genes. Doppler echocardiography revealed that these transgenic mice had increased left ventricular wall thickness and decreased left ventricular (LV) volumes, increased LV stiffness with 20% reduction in early diastolic LV filling (peak E), and 35% decline in peak E-to-peak A (late diastolic filling) ratio. The observed changes, especially those in the E/A ratio, are similar to those seen clinically in late life as a part of human adult myocardial aging.
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Affiliation(s)
- Xiaomin Zhang
- Reynolds Center on Aging, Dept. of Geriatrics, Univ. of Arkansas for Medical Science, 4301 West Markham Ave., Slot 748, Little Rock, AR 72205, USA.
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24
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Liu HW, Halayko AJ, Fernandes DJ, Harmon GS, McCauley JA, Kocieniewski P, McConville J, Fu Y, Forsythe SM, Kogut P, Bellam S, Dowell M, Churchill J, Lesso H, Kassiri K, Mitchell RW, Hershenson MB, Camoretti-Mercado B, Solway J. The RhoA/Rho kinase pathway regulates nuclear localization of serum response factor. Am J Respir Cell Mol Biol 2003; 29:39-47. [PMID: 12600823 DOI: 10.1165/rcmb.2002-0206oc] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
RhoA and its downstream target Rho kinase regulate serum response factor (SRF)-dependent skeletal and smooth muscle gene expression. We previously reported that long-term serum deprivation reduces transcription of smooth muscle contractile apparatus encoding genes, by redistributing SRF out of the nucleus. Because serum components stimulate RhoA activity, these observations suggest the hypothesis that the RhoA/Rho kinase pathway regulates SRF-dependent smooth muscle gene transcription in part by controlling SRF subcellular localization. Our present results support this hypothesis: cotransfection of cultured airway myocytes with a plasmid expressing constitutively active RhoAV14 selectively enhanced transcription from the SM22 and smooth muscle myosin heavy chain promoters and from a purely SRF-dependent promoter, but had no effect on transcription from the MSV-LTR promoter or from an AP2-dependent promoter. Conversely, inhibition of the RhoA/Rho kinase pathway by cotransfection with a plasmid expressing dominant negative RhoAN19, by cotransfection with a plasmid expressing Clostridial C3 toxin, or by incubation with the Rho kinase inhibitor, Y-27632, all selectively reduced SRF-dependent smooth muscle promoter activity. Furthermore, treatment with Y-27632 selectively reduced binding of SRF from nuclear extracts to its consensus DNA target, selectively reduced nuclear SRF protein content, and partially redistributed SRF from nucleus to cytoplasm, as revealed by quantitative immunocytochemistry. Treatment of cultured airway myocytes with latrunculin B, which reduces actin polymerization, also caused partial redistribution of SRF into the cytoplasm. Together, these results demonstrate for the first time that the RhoA/Rho kinase pathway controls smooth muscle gene transcription in differentiated smooth muscle cells, in part by regulating the subcellular localization of SRF. It is conceivable that the RhoA/Rho kinase pathway influences SRF localization through its effect on actin polymerization dynamics.
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Affiliation(s)
- Hong Wei Liu
- Departments of Medicine and Pediatrics, University of Chicago, Chicago, IL 60637, USA
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25
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Scott SD, Joiner MC, Marples B. Optimizing radiation-responsive gene promoters for radiogenetic cancer therapy. Gene Ther 2002; 9:1396-402. [PMID: 12365005 DOI: 10.1038/sj.gt.3301822] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2002] [Accepted: 05/23/2002] [Indexed: 11/08/2022]
Abstract
We have been developing synthetic gene promoters responsive to clinical doses of ionizing radiation (IR) for use in suicide gene therapy vectors. The crucial DNA sequences utilized are units with the consensus motif CC(A/T)(6)GG, known as CArG elements, derived from the IR-responsive Egr1 gene. In this study we have investigated the parameters needed to enhance promoter activation to radiation. A series of plasmid vectors containing different enhancer/promoters were constructed, transiently transfected into tumor cells (MCF-7 breast adenocarcinoma and U-373MG glioblastoma) and expression of a downstream reporter assayed. Results revealed that increasing the number of CArG elements, up to a certain level, increased promoter radiation-response; from a fold-induction of 1.95 +/- 0.17 for four elements to 2.74 +/- 0.17 for nine CArGs of the same sequence (for MCF-7 cells). Specific alteration of the core A/T sequences caused an even greater positive response, with fold-inductions of 1.71 +/- 0.23 for six elements of prototype sequence compared with 2.96 +/- 0.52 for one of the new sequences following irradiation. Alteration of spacing (from six to 18 nucleotides) between elements had little effect, as did the addition of an adjacent Sp1 binding site. Combining the optimum number and sequence of CArG elements in an additional enhancer was found to produce the best IR induction levels. Furthermore, the improved enhancers also performed better than the previously reported prototype when used in in vitro and in vivo experimental GDEPT. We envisage such enhancers will be used to drive suicide gene expression from vectors delivered to a tumor within an irradiated field. The modest, but tight expression described in the present study could be amplified using a molecular 'switch' system as previously described using Cre/LoxP. In combination with targeted delivery, this strategy has great potential for significantly improving the efficacy of cancer treatment in the large number of cases where radiotherapy is currently employed.
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Affiliation(s)
- S D Scott
- Department of Experimental Radiation Oncology, Gray Cancer Institute, Northwood, Middlesex, UK
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26
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Lavelin I, Meiri N, Einat M, Genina O, Pines M. Mechanical strain regulation of the chicken glypican-4 gene expression in the avian eggshell gland. Am J Physiol Regul Integr Comp Physiol 2002; 283:R853-61. [PMID: 12228054 DOI: 10.1152/ajpregu.00088.2002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Comparison of RNA fingerprinting of the avian eggshell gland (ESG) without and with an egg revealed upregulation of a 382-bp cDNA fragment that showed high homology to the mammalian glypican 4 (GPC-4). The gene sequence revealed a conserved glypican signature, a glycosyl phosphatidyl inositol-anchorage site, and cystein residues, most of which were conserved. GPC-4 was expressed in the ESG in a circadian fashion only during the period of eggshell calcification, when maximal mechanical strain was imposed. Removal of the egg just before to its entry into the ESG, with consequent elimination of the mechanical strain, caused reduction in the gene expression. Artificial application of the mechanical strain induced expression of the GPC-4 gene that was related to the level of the strain. GPC-4 expression was strain dependent in other parts of the oviduct. In the ESG, GPC-4 was expressed exclusively by the glandular epithelium and not by the pseudostratified epithelium facing the lumen. In summary, we cloned the avian homologue of GPC-4, established its pattern of expression in the avian ESG, and demonstrated for the first time that this gene is regulated by mechanical strain.
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Affiliation(s)
- Irena Lavelin
- Institute of Animal Science, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
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27
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Psichari E, Balmain A, Plows D, Zoumpourlis V, Pintzas A. High activity of serum response factor in the mesenchymal transition of epithelial tumor cells is regulated by RhoA signaling. J Biol Chem 2002; 277:29490-5. [PMID: 12039949 DOI: 10.1074/jbc.m112368200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serum response factor (SRF) regulates the transcription of target genes by binding to serum response elements in dimeric form and by interacting with ternary complex factors. In this study, we have analyzed the role of the serum response factor and mechanisms that regulate its activity in tumor progression utilizing a multistage model of mouse skin carcinogenesis. We demonstrate elevated SRF DNA binding activity only in the cell lines that have undergone an epithelial to mesenchymal transition and have increased actin stress fiber formation. Transient transfection experiments of activated or dominant negative forms of RhoA showed that the high activity of SRF and the induced formation of actin stress fibers in cells with spindle morphology were mediated by RhoA signaling. A dominant negative form of SRF inhibited RhoA-induced actin polymerization and stress fiber formation. The DNA binding activity of SRF in mesenchymal tumor cells was also correlated with elevated expression of SRF target genes, similar to SRF itself, actin, and vinculin. These observations suggest for the first time that SRF may play an important role in tumor progression, specifically at the transition to an invasive metastatic stage of carcinogenesis.
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Affiliation(s)
- Eleni Psichari
- Laboratory of Signal Mediated Gene Expression, Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, 48, Vasileos Constantinou Avenue, 116 35 Athens, Greece
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28
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Rao MK, Maiti S, Ananthaswamy HN, Wilkinson MF. A highly active homeobox gene promoter regulated by Ets and Sp1 family members in normal granulosa cells and diverse tumor cell types. J Biol Chem 2002; 277:26036-45. [PMID: 11986330 DOI: 10.1074/jbc.m203374200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One mechanism by which normal cells become converted to tumor cells involves the aberrant transcriptional activation of genes that are normally silent. We characterize a promoter that normally exhibits highly tissue- and stage-specific expression but displays ubiquitous expression when cells become immortalized or malignant, regardless of their lineage or tissue origin. This promoter normally drives the expression of the Pem homeobox gene in specific cell types in ovary and placenta but is aberrantly expressed in lymphomas, neuroblastomas, retinoblastomas, carcinomas, and sarcomas. By deletion analysis we identified a region between nucleotides -80 and -104 that was absolutely critical for the expression from this distal Pem promoter (Pem Pd). Site-specific mutagenesis and transfection studies revealed that this region contains two consensus Ets sites and a single Sp1 site that were necessary for Pem Pd expression. Gel shift analysis showed that Ets and Sp1 family members bound to these sites. Transfection studies demonstrated that the Ets family members Elf1 and Gabp and the Sp1 family members Sp1 and Sp3 transactivated the Pem Pd. Surprisingly, we found that Sp3 was a more potent activator of the Pem Pd than was Sp1; this is unusual, because Sp3 is either a weak activator or a repressor of most other promoters. Activation by either Elf1 or Gabp required an intact Sp1 family member binding site, suggesting that Ets and Sp1 family members cooperate to activate Pem Pd transcription. Expression from the Pem Pd (either transiently transfected or endogenous) depended on the Ras pathway, which could explain both its Ets- and Sp1-dependent expression in normal cells and its aberrant expression in tumor cells, in which ras protooncogenes are frequently mutated. We suggest that the Pem Pd may be a useful model system to understand the molecular mechanism by which a tissue-specific promoter can be corrupted in tumor cells.
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Affiliation(s)
- Manjeet K Rao
- Department of Immunology, the University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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29
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Zhang X, Chai J, Azhar G, Sheridan P, Borras AM, Furr MC, Khrapko K, Lawitts J, Misra RP, Wei JY. Early postnatal cardiac changes and premature death in transgenic mice overexpressing a mutant form of serum response factor. J Biol Chem 2001; 276:40033-40. [PMID: 11514558 DOI: 10.1074/jbc.m104934200] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Serum response factor (SRF) is a key regulator of a number of extracellular signal-regulated genes important for cell growth and differentiation. A form of the SRF gene with a double mutation (dmSRF) was generated. This mutation reduced the binding activity of SRF protein to the serum response element and reduced the capability of SRF to activate the atrial natriuretic factor promoter that contains the serum response element. Cardiac-specific overexpression of dmSRF attenuated the total SRF binding activity and resulted in remarkable morphologic changes in the heart of the transgenic mice. These mice had dilated atrial and ventricular chambers, and their ventricular wall thicknesses were only 1/2 to 1/3 the thickness of that of nontransgenic mice. Also these mice had smaller cardiac myocytes and had less myofibrils in their myocytes relative to nontransgenic mice. Altered gene expression and slight interstitial fibrosis were observed in the myocardium of the transgenic mice. All the transgenic mice died within the first 12 days after birth, because of the early onset of severe, dilated cardiomyopathy. These results indicate that dmSRF overexpression in the heart apparently alters cardiac gene expression and blocks normal postnatal cardiac growth and development.
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Affiliation(s)
- X Zhang
- Department of Medicine, Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, MA 02215, USA
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30
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Black AR, Black JD, Azizkhan-Clifford J. Sp1 and krüppel-like factor family of transcription factors in cell growth regulation and cancer. J Cell Physiol 2001; 188:143-60. [PMID: 11424081 DOI: 10.1002/jcp.1111] [Citation(s) in RCA: 819] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Sp/KLF family contains at least twenty identified members which include Sp1-4 and numerous krüppel-like factors. Members of the family bind with varying affinities to sequences designated as 'Sp1 sites' (e.g., GC-boxes, CACCC-boxes, and basic transcription elements). Family members have different transcriptional properties and can modulate each other's activity by a variety of mechanisms. Since cells can express multiple family members, Sp/KLF factors are likely to make up a transcriptional network through which gene expression can be fine-tuned. 'Sp1 site'-dependent transcription can be growth-regulated, and the activity, expression, and/or post-translational modification of multiple family members is altered with cell growth. Furthermore, Sp/KLF factors are involved in many growth-related signal transduction pathways and their overexpression can have positive or negative effects on proliferation. In addition to growth control, Sp/KLF factors have been implicated in apoptosis and angiogenesis; thus, the family is involved in several aspects of tumorigenesis. Consistent with a role in cancer, Sp/KLF factors interact with oncogenes and tumor suppressors, they can be oncogenic themselves, and altered expression of family members has been detected in tumors. Effects of changes in Sp/KLF factors are context-dependent and can appear contradictory. Since these factors act within a network, this diversity of effects may arise from differences in the expression profile of family members in various cells. Thus, it is likely that the properties of the overall network of Sp/KLF factors play a determining role in regulation of cell growth and tumor progression.
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Affiliation(s)
- A R Black
- Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.
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31
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Gineitis D, Treisman R. Differential usage of signal transduction pathways defines two types of serum response factor target gene. J Biol Chem 2001; 276:24531-9. [PMID: 11342553 DOI: 10.1074/jbc.m102678200] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of the transcription factor serum response factor (SRF) is dependent on Rho-controlled changes in actin dynamics. We used pathway-specific inhibitors to compare the roles of actin dynamics, extracellular signal-regulated kinase (ERK) signaling, and phosphatidylinositol 3-kinase in signaling either to SRF itself or to four cellular SRF target genes. Serum, lysophosphatidic acid, platelet-derived growth factor, and phorbol 12-myristate 13-acetate (PMA) each activated transcription of a stably integrated SRF reporter gene dependent on functional RhoA GTPase. Inhibition of mitogen-activated protein kinase-ERK kinase (MEK) signalling reduced activation of the SRF reporter by all stimuli by about 50%, except for PMA, which was effectively blocked. Inhibition of phosphatidylinositol 3-kinase slightly reduced reporter activation by serum and lysophosphatidic acid but substantially inhibited activation by platelet-derived growth factor and PMA. Reporter induction by all stimuli was absolutely dependent on actin dynamics. Regulation of the SRF (srf) and vinculin (vcl) genes was similar to that of the SRF reporter gene; activation by all stimuli was Rho-dependent and required actin dynamics but was largely independent of MEK activity. In contrast, activation of fos and egr1 occurred independently of RhoA and actin polymerization but was almost completely dependent on MEK activation. These results show that at least two classes of SRF target genes can be distinguished on the basis of their relative sensitivity to RhoA-actin and MEK-ERK signaling pathways.
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Affiliation(s)
- D Gineitis
- Transcription Laboratory, Imperial Cancer Research Fund Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom
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Shah V, Bharadwaj S, Kaibuchi K, Prasad GL. Cytoskeletal organization in tropomyosin-mediated reversion of ras-transformation: Evidence for Rho kinase pathway. Oncogene 2001; 20:2112-21. [PMID: 11360195 DOI: 10.1038/sj.onc.1204291] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2000] [Revised: 01/19/2001] [Accepted: 01/23/2001] [Indexed: 01/08/2023]
Abstract
Tropomyosin (TM) family of cytoskeletal proteins is implicated in stabilizing actin microfilaments. Many TM isoforms, including tropomyosin-1 (TM1), are down-regulated in transformed cells. Previously we demonstrated that TM1 is a suppressor of the malignant transformation, and that TM1 reorganizes microfilaments in the transformed cells. To investigate how TM1 induces microfilament organization in transformed cells, we utilized ras-transformed NIH3T3 (DT) cells, and those transduced to express TM1, and/or TM2. Enhanced expression of TM1 alone, but not TM2, results in re-emergence of microfilaments; TM1, together with TM2 remarkably improves microfilament architecture. TM1 induced cytoskeletal reorganization involves an enhanced expression of caldesmon, but not vinculin, alpha-actinin, or gelsolin. In addition, TM1-induced cytoskeletal reorganization and the revertant phenotype appears to involve re-activation of RhoA controlled pathways in DT cells. RhoA expression, which is suppressed in DT cells, is significantly increased in TM1-expressing cells, without detectable changes in the expression of Rac or Cdc42. Furthermore, expression of a dominant negative Rho kinase, or treatment with Y-27632 disassembled microfilaments in normal NIH3T3 and in TM1 expressing cells. These data suggest that reactivation of Rho kinase directed pathways are critical for TM1-mediated microfilament assemblies.
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Affiliation(s)
- V Shah
- Wistar Institute of Anatomy and Cell Biology, Philadelphia, Pennsylvania, USA
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