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Transcriptomic mapping uncovers Purkinje neuron plasticity driving learning. Nature 2022; 605:722-727. [PMID: 35545673 PMCID: PMC9887520 DOI: 10.1038/s41586-022-04711-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 03/31/2022] [Indexed: 02/03/2023]
Abstract
Cellular diversification is critical for specialized functions of the brain including learning and memory1. Single-cell RNA sequencing facilitates transcriptomic profiling of distinct major types of neuron2-4, but the divergence of transcriptomic profiles within a neuronal population and their link to function remain poorly understood. Here we isolate nuclei tagged5 in specific cell types followed by single-nucleus RNA sequencing to profile Purkinje neurons and map their responses to motor activity and learning. We find that two major subpopulations of Purkinje neurons, identified by expression of the genes Aldoc and Plcb4, bear distinct transcriptomic features. Plcb4+, but not Aldoc+, Purkinje neurons exhibit robust plasticity of gene expression in mice subjected to sensorimotor and learning experience. In vivo calcium imaging and optogenetic perturbation reveal that Plcb4+ Purkinje neurons have a crucial role in associative learning. Integrating single-nucleus RNA sequencing datasets with weighted gene co-expression network analysis uncovers a learning gene module that includes components of FGFR2 signalling in Plcb4+ Purkinje neurons. Knockout of Fgfr2 in Plcb4+ Purkinje neurons in mice using CRISPR disrupts motor learning. Our findings define how diversification of Purkinje neurons is linked to their responses in motor learning and provide a foundation for understanding their differential vulnerability to neurological disorders.
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2
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Wang B, Guo H, Yu H, Chen Y, Xu H, Zhao G. The Role of the Transcription Factor EGR1 in Cancer. Front Oncol 2021; 11:642547. [PMID: 33842351 PMCID: PMC8024650 DOI: 10.3389/fonc.2021.642547] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/25/2021] [Indexed: 12/12/2022] Open
Abstract
Early growth response factor 1 (EGR1) is a transcription factor that is mainly involved in the processes of tissue injury, immune responses, and fibrosis. Recent studies have shown that EGR1 is closely related to the initiation and progression of cancer and may participate in tumor cell proliferation, invasion, and metastasis and in tumor angiogenesis. Nonetheless, the specific mechanism whereby EGR1 modulates these processes remains to be elucidated. This review article summarizes possible mechanisms of action of EGR1 in tumorigenesis and tumor progression and may serve as a reference for clinical efficacy predictions and for the discovery of new therapeutic targets.
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Affiliation(s)
- Bin Wang
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun, China
| | - Hanfei Guo
- Cancer Center, The First Hospital of Jilin University, Changchun, China
| | - Hongquan Yu
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun, China
| | - Yong Chen
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun, China
| | - Haiyang Xu
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun, China
| | - Gang Zhao
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun, China
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3
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Li TT, Liu MR, Pei DS. Friend or foe, the role of EGR-1 in cancer. Med Oncol 2019; 37:7. [PMID: 31748910 DOI: 10.1007/s12032-019-1333-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 11/11/2019] [Indexed: 12/18/2022]
Abstract
Early growth response-1 (EGR-1), also termed NEFI-A and Krox-24, as a multi-domain protein is implicated in several vital physiological processes, including development, metabolism, cell growth and proliferation. Previous studies have implied that EGR-1 was producing in response to the tissue injury, immune response and fibrosis. Meanwhile, emerging studies stressed the pronounced correlation of EGR-1 and human cancers. Nevertheless, the intricate mechanisms of cancer-reduce EGR-1 alteration still poorly characterized. In the review, we evaluated the effects of EGR-1 in tumor cell proliferation, apoptosis, migration, invasion and tumor microenvironment, and then, we dwell on the intricate signaling pathways that EGR-1 involved in. The aberrantly expressed of EGR-1 in cancers are expected to provide a new cancer therapy strategy or a new marker for assessing treatment efficacy.
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Affiliation(s)
- Tong-Tong Li
- Department of Pathology, Xuzhou Medical University, 209 Tong-shan Road, Xuzhou, 221004, Jiangsu, People's Republic of China
| | - Man-Ru Liu
- Department of Pathology, Xuzhou Medical University, 209 Tong-shan Road, Xuzhou, 221004, Jiangsu, People's Republic of China
| | - Dong-Sheng Pei
- Department of Pathology, Xuzhou Medical University, 209 Tong-shan Road, Xuzhou, 221004, Jiangsu, People's Republic of China.
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4
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Genomic Instability in Human Pluripotent Stem Cells Arises from Replicative Stress and Chromosome Condensation Defects. Cell Stem Cell 2015; 18:253-61. [PMID: 26669899 DOI: 10.1016/j.stem.2015.11.003] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 08/31/2015] [Accepted: 11/05/2015] [Indexed: 12/27/2022]
Abstract
Human pluripotent stem cells (hPSCs) frequently acquire chromosomal aberrations such as aneuploidy in culture. These aberrations progressively increase over time and may compromise the properties and clinical utility of the cells. The underlying mechanisms that drive initial genomic instability and its continued progression are largely unknown. Here, we show that aneuploid hPSCs undergo DNA replication stress, resulting in defective chromosome condensation and segregation. Aneuploid hPSCs show altered levels of actin cytoskeletal genes controlled by the transcription factor SRF, and overexpression of SRF rescues impaired chromosome condensation and segregation defects in aneuploid hPSCs. Furthermore, SRF downregulation in diploid hPSCs induces replication stress and perturbed condensation similar to that seen in aneuploid cells. Together, these results suggest that decreased SRF expression induces replicative stress and chromosomal condensation defects that underlie the ongoing chromosomal instability seen in aneuploid hPSCs. A similar mechanism may also operate during initiation of instability in diploid cells.
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5
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Lee SM, Vasishtha M, Prywes R. Activation and repression of cellular immediate early genes by serum response factor cofactors. J Biol Chem 2010; 285:22036-49. [PMID: 20466732 DOI: 10.1074/jbc.m110.108878] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The induction of expression of many cellular immediate early genes (IEG) involves the transcription factor serum response factor (SRF). Two families of SRF coactivators have also been implicated in IEG induction, the ternary complex factors (TCFs), ELK1, Sap1, and Net, and the myocardin-related factors, MKL1 and MKL2. We found that serum induction of some SRF target genes is preferentially regulated by MKL1/2, whereas others are redundantly activated by both TCFs and MKL1/2. Yet ELK1 can also repress transcription. Binding of ELK1 and MKL1 to SRF has been found to be mutually exclusive in vitro, suggesting that ELK1 could repress expression of IEGs by blocking MKL1 binding. We characterized the in vivo binding of MKL1 and ELK1 to target genes and found an inverse relationship of serum-induced MKL1 binding and serum-decreased ELK1 binding. However, experiments with short hairpin RNA-mediated MKL1/2 depletion and expression of a nuclear MKL1 (N100) variant in stably transfected cells failed to alter ELK1 binding, suggesting that ELK1 binding to target genes is regulated independently of MKL1/2. Nevertheless, we found that short interfering RNA-mediated depletion of TCFs increased target gene expression in cells containing the N100 MKL1 activator, most notably in cells under continuous growth conditions. These results indicate that the TCFs can function both as activators and repressors of target gene expression depending upon the cellular growth conditions.
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Affiliation(s)
- Seung-Min Lee
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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6
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Major ML, Cheung HS, Misra RP. Basic calcium phosphate crystals activate c-fos expression through a Ras/ERK dependent signaling mechanism. Biochem Biophys Res Commun 2007; 355:654-60. [PMID: 17307136 PMCID: PMC1855205 DOI: 10.1016/j.bbrc.2007.01.177] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Accepted: 01/31/2007] [Indexed: 10/23/2022]
Abstract
Diseases caused by calcium pyrophosphate dihydrate (CPPD) and basic calcium phosphate (BCP) crystals occur frequently in osteoarthritic joints. Both crystals induce mitogenesis, metalloproteinase synthesis and secretion by fibroblasts and chondrocytes, promoting degradation of articular tissue. We investigated the mechanism by which BCP activates the c-fos proto-oncogene, which has been shown to activate various matrix metalloproteinases (MMPs). We demonstrate that BCP crystals induce c-fos expression primarily through a Ras/ERK-dependent signaling mechanism targeting two highly conserved regulatory binding sites, the serum response element (SRE) and the cAMP response element (CRE). These results establish a calcium crystal induced, calcium/calmodulin independent, signaling pathway in which BCP crystals activate Ras/MAPK, which can directly target an SRF-containing transcription factor complex, to induce fibroblasts to secrete metalloproteinases.
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Affiliation(s)
| | - Herman S. Cheung
- Geriatric Research Education and Clinical Center, VA Medical Center and Department of Medicine, University of Miami School of Medicine, Miami, FL 33101
| | - Ravi P. Misra
- *To whom correspondence should be addressed: Tel. # 414-456-8433, Fax # 414-456-6510, Internet:
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7
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Chen Y, Leal AD, Patel S, Gorski DH. The homeobox gene GAX activates p21WAF1/CIP1 expression in vascular endothelial cells through direct interaction with upstream AT-rich sequences. J Biol Chem 2007; 282:507-17. [PMID: 17074759 PMCID: PMC1865102 DOI: 10.1074/jbc.m606604200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Tumors secrete pro-angiogenic factors to induce the ingrowth of blood vessels from the surrounding stroma, the end targets of which are vascular endothelial cells (ECs). The homeobox gene GAX inhibits angiogenesis and induces p21(WAF1/CIP1) expression in vascular ECs. To elucidate the mechanism through which GAX activates p21(WAF1/CIP1) expression, we constructed GAX cDNAs with deletions of the N-terminal domain, the homeodomain, or the C-terminal domain and then assessed these constructs for their ability to activate p21(WAF1/CIP1). There was an absolute requirement for the homeodomain, whereas deleting the C-terminal domain decreased but did not abolish transactivation of the p21(WAF1/CIP1) promoter by GAX. Deleting the N-terminal domain did abolish transactivation. Next, we performed chromatin immunoprecipitation and found, approximately 15 kb upstream of the p21(WAF1/CIP1) ATG codon, an ATTA-containing GAX-binding site (designated A6) with a sequence similar to that of other homeodomain-binding sites. GAX was able to bind to A6 in a homeodomain-dependent manner and thereby activate the expression of a reporter gene coupled to this sequence, and this activation was abolished by mutating specific residues in this sequence. On the basis of the sequence of A6, we were then able to locate other ATTA-containing sequences that also bound GAX and activated transcription in reporter constructs. Finally, we found that the ability of these GAX deletions to induce G(0)/G(1) arrest correlates with their ability to transactivate the p21(WAF1/CIP1) promoter. We conclude that GAX activates p21(WAF1/CIP1) through multiple upstream AT-rich sequences. Given the multiple biological activities of GAX in regulating EC function, identification of a putative GAX-binding site will allow the study of how GAX activates or represses other downstream targets to inhibit angiogenesis.
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Affiliation(s)
- Yun Chen
- From the Division of Surgical Oncology, UMDNJ-Robert Wood Johnson Medical School, The Cancer Institute of New Jersey, New Brunswick, NJ 088901
| | - Alejandro D. Leal
- From the Division of Surgical Oncology, UMDNJ-Robert Wood Johnson Medical School, The Cancer Institute of New Jersey, New Brunswick, NJ 088901
| | - Sejal Patel
- From the Division of Surgical Oncology, UMDNJ-Robert Wood Johnson Medical School, The Cancer Institute of New Jersey, New Brunswick, NJ 088901
| | - David H. Gorski
- From the Division of Surgical Oncology, UMDNJ-Robert Wood Johnson Medical School, The Cancer Institute of New Jersey, New Brunswick, NJ 088901
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8
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Shin SY, Bahk YY, Ko J, Chung IY, Lee YS, Downward J, Eibel H, Sharma PM, Olefsky JM, Kim YH, Lee B, Lee YH. Suppression of Egr-1 transcription through targeting of the serum response factor by oncogenic H-Ras. EMBO J 2006; 25:1093-103. [PMID: 16456537 PMCID: PMC1409727 DOI: 10.1038/sj.emboj.7600987] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 01/16/2006] [Indexed: 11/09/2022] Open
Abstract
The transcription factor Egr-1 functions as a key regulator in cellular growth, differentiation, and apoptosis. The loss of Egr-1 expression is closely associated with tumor development, although the molecular mechanism behind the suppression of Egr-1 is largely unknown. In this report, we show that growth factor-induced transcriptional activation of Egr-1 gene is downregulated by chronic expression of oncogenic H-Ras in NIH3T3 fibroblasts. Our results demonstrate that phosphoinositide 3-kinase (PI3K) signaling is necessary for oncogenic H-Ras-mediated reduction of Egr-1 gene expression. Aberrant activation of PI3K signaling by oncogenic Ras decreased the level of serum response factor (SRF) protein through the acceleration of proteolysis, which resulted in decreased SRF binding to the serum response element (SRE) sites within the Egr-1 promoter, leading to the suppression of Egr-1 transcription. Inhibition of PI3K signaling restored the downregulation of SRF and Egr-1 expression caused by oncogenic Ras. Our findings suggest a novel signaling mechanism by which prolonged activation of oncogenic H-Ras can trigger the loss of tumor suppressor Egr-1 through the PI3K pathway in NIH3T3 fibroblast model cell lines.
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Affiliation(s)
- Soon Young Shin
- Division of Molecular & Life Science, College of Science & Technology, Hanyang University, Ansan, Korea
| | - Young Yil Bahk
- Protein Network Research Center, Yonsei University, Seoul, Korea
| | - Jesang Ko
- School of Life Sciences and Biotechnology, Korea University, Seoul, Korea
| | - Il-Yup Chung
- Division of Molecular & Life Science, College of Science & Technology, Hanyang University, Ansan, Korea
| | - Young Seek Lee
- Division of Molecular & Life Science, College of Science & Technology, Hanyang University, Ansan, Korea
| | | | | | - Prem M Sharma
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, CA, USA
| | - Jerrold M Olefsky
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, CA, USA
| | - Young-Ho Kim
- Department of Microbiology, Kyungpook National University, Daegu, Korea
| | - Bonghee Lee
- Department of Anatomy and Neurobiology, College of Medicine, Institute of Medical Science, Cheju National University, Jeju, Korea
| | - Young Han Lee
- Division of Molecular & Life Science, College of Science & Technology, Hanyang University, Ansan, Korea
- Division of Molecular & Life Science, College of Science & Technology, Hanyang University, Ansan 426-791, Korea. Tel.: +82 31 400 5517; Fax: +82 31 416 9781; E-mail:
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9
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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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Shao RX, Otsuka M, Kato N, Taniguchi H, Hoshida Y, Moriyama M, Kawabe T, Omata M. Acyclic retinoid inhibits human hepatoma cell growth by suppressing fibroblast growth factor-mediated signaling pathways. Gastroenterology 2005; 128:86-95. [PMID: 15633126 DOI: 10.1053/j.gastro.2004.09.077] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND & AIMS Hepatocellular carcinoma (HCC) is one of the most common human malignancies. Its high mortality rate is mainly a result of high intrahepatic recurrence. The novel synthetic retinoid acyclic retinoid (ACR) has been reported to prevent the recurrence of human HCC after surgical resection of primary tumors, but the molecular mechanisms underlying its effects remain to be elucidated. In this study, we clarified the molecular targets of ACR. METHODS The inhibitory effects by ACR on growth were examined. Intracellular signaling induced by ACR was comprehensively studied by a reporter assay. Gene expression changes by ACR were examined using a microarray. From these results, a candidate signaling pathway modulated by ACR was determined and whether antagonizing this pathway reverses the effect was examined. RESULTS We show that ACR inhibits the growth of HCC cells through the down-regulation of fibroblast growth factor (FGF) receptor 3 expression and FGF-mediated signaling, which in turn suppresses the activity of Rho and serum response factor-mediated transcription. Conversely, overexpression of the active form of FGF receptor 3 or the addition of FGF reverses the ACR-mediated inhibition of growth. In addition, silencing the FGF receptor 3 gene by RNA interference inhibits cell growth. CONCLUSIONS These studies show that ACR is a potent inhibitor of FGF signaling and that selective blocking of the FGF-mediated pathway could be a promising therapeutic approach for the management of patients with HCC.
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Affiliation(s)
- Run-Xuan Shao
- Department of Gastroenterology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
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11
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Kasza A, O'Donnell A, Gascoigne K, Zeef LAH, Hayes A, Sharrocks AD. The ETS domain transcription factor Elk-1 regulates the expression of its partner protein, SRF. J Biol Chem 2004; 280:1149-55. [PMID: 15531578 DOI: 10.1074/jbc.m411161200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ternary complex factors (TCF) are a subfamily of ETS domain transcription factors that bind and activate serum response elements (SREs) in the promoters of target genes in a ternary complex with a second transcription factor, serum response factor (SRF). Here, we have identified the SRF gene as a target for the TCFs, thereby providing a positive feedback loop whereby TCF activation leads to the enhancement of the expression of its partner protein SRF. The binding of the TCF Elk-1 to the SRF promoter and subsequent regulation of SRF expression occurs in a ternary complex-dependent manner. Our data therefore reveal that SRF is an important target for the ERK and Rho signaling pathways that converge on a ternary TCF-SRF complex at the SRE on the SRF promoter.
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Affiliation(s)
- Aneta Kasza
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, United Kingdom
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12
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Chai J, Jones MK, Tarnawski AS. Serum response factor is a critical requirement for VEGF signaling in endothelial cells and VEGF-induced angiogenesis. FASEB J 2004; 18:1264-6. [PMID: 15180964 DOI: 10.1096/fj.03-1232fje] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Angiogenesis, new capillary blood vessel formation, is essential for embryonic development, wound healing, and cancer growth. Vascular endothelial growth factor (VEGF) induces angiogenesis by activating endothelial cell migration and proliferation. Serum response factor (SRF) is a transcription factor important for embryonic development and activation of immediate early gene expression. The roles of SRF in endothelial cell biology and angiogenesis have not been explored. Here we demonstrate that SRF is a downstream mediator of VEGF signaling in endothelial cells and a critical requirement for VEGF-induced angiogenesis. Knockdown of SRF protein levels in human and rat endothelial cells abolished VEGF-induced in vitro angiogenesis, impaired endothelial cell migration and proliferation, and inhibited VEGF-induced actin polymerization and immediate early gene expression. Injection of SRF antisense expression plasmid into gastric ulcers in rats significantly inhibited in vivo angiogenesis in granulation tissue. Mechanistically, this study also revealed that VEGF promotes SRF expression and nuclear translocation and increases SRF binding activity to DNA in endothelial cells through both Rho-actin and MEK-ERK dependent signaling pathways. These findings have potential therapeutic implications, e.g., local anti-SRF treatment may inhibit angiogenesis crucial for tumor growth.
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MESH Headings
- Acetic Acid/toxicity
- Actins/analysis
- Animals
- Cell Division/drug effects
- Cell Movement/drug effects
- Cells, Cultured/cytology
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Cells, Cultured/physiology
- Collagen
- Culture Media, Serum-Free
- DNA, Recombinant/administration & dosage
- DNA, Recombinant/therapeutic use
- Drug Combinations
- Endothelial Cells/cytology
- Endothelial Cells/drug effects
- Endothelial Cells/metabolism
- Endothelial Cells/physiology
- Endothelium, Vascular/cytology
- Genetic Therapy
- Humans
- Injections, Intralesional
- Laminin
- Neovascularization, Physiologic/drug effects
- Neovascularization, Physiologic/physiology
- Oligodeoxyribonucleotides, Antisense/pharmacology
- Proteoglycans
- Rats
- Recombinant Proteins/pharmacology
- Serum Response Factor/antagonists & inhibitors
- Serum Response Factor/biosynthesis
- Serum Response Factor/genetics
- Serum Response Factor/physiology
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Stomach/blood supply
- Stomach Ulcer/chemically induced
- Stomach Ulcer/metabolism
- Stomach Ulcer/therapy
- Umbilical Veins
- Vascular Endothelial Growth Factor A/pharmacology
- Vascular Endothelial Growth Factor A/physiology
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Affiliation(s)
- Jianyuan Chai
- Department of Medicine/Gastroenterology, VA Medical Center, Long Beach, California 90822, USA
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13
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Jackson TA, Koterwas DM, Morgan MA, Bradford AP. Fibroblast growth factors regulate prolactin transcription via an atypical Rac-dependent signaling pathway. Mol Endocrinol 2003; 17:1921-30. [PMID: 12843210 DOI: 10.1210/me.2003-0167] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Fibroblast growth factors (FGFs) play a critical role in pituitary development and in pituitary tumor formation and progression. We have previously characterized FGF signal transduction and regulation of the tissue-specific rat prolactin (rPRL) promoter in GH4 pituitary cells. FGF induction of rPRL transcription is independent of Ras, but mediated by a protein kinase C-delta (PKCdelta)-dependent activation of MAPK (ERK). Here we demonstrate a functional role for the Rho family monomeric G protein, Rac1, in FGF regulation of PRL gene expression via an atypical signaling pathway. Expression of dominant negative Rac, but not RhoA or Cdc42, selectively inhibited FGF-induced rPRL promoter activity. Moreover, expression of dominant negative Rac also attenuated FGF-2 and FGF-4 stimulation of MAPK (ERK). However, in contrast to other Rac-dependent signaling pathways, FGF activation of rPRL promoter activity was independent of the c-Jun N-terminal kinase (JNK) and phosphoinositide 3-kinase/Akt cascades. FGFs failed to activate JNK1 or JNK2, and expression of dominant negative JNK or Akt constructs did not block FGF-induced PRL transcription. Consistent with the role of PKCdelta in FGF regulation of PRL gene expression, activation of the rPRL promoter was blocked by an inhibitor of phospholipase Cgamma (PLCgamma) activity. FGF treatment also induced rapid tyrosine phosphorylation of PLCgamma in a Rac-dependent manner. These results suggest that FGF-2 and FGF-4 activate PRL gene expression via a novel Rac1, PLCgamma, PKCdelta, and ERK cascade, independent of phosphoinositol-3-kinase and JNK.
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Affiliation(s)
- Twila A Jackson
- Section of Basic Reproductive Science, Department of Obstetrics & Gynecology, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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14
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Ader I, Muller C, Bonnet J, Favre G, Cohen-Jonathan E, Salles B, Toulas C. The radioprotective effect of the 24 kDa FGF-2 isoform in HeLa cells is related to an increased expression and activity of the DNA dependent protein kinase (DNA-PK) catalytic subunit. Oncogene 2002; 21:6471-9. [PMID: 12226750 DOI: 10.1038/sj.onc.1205838] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2002] [Revised: 06/05/2002] [Accepted: 06/28/2002] [Indexed: 11/09/2022]
Abstract
We previously reported that overexpression of the 24 kDa basic fibroblast factor (or FGF-2) isoform provides protection from the cytotoxic effect of ionizing radiation (IR). DNA double-strand breaks (DSB), the IR-induced lethal lesions, are mainly repaired in human cells by non-homologous end joining system (NHEJ). NHEJ reaction is dependent on the DNA-PK holoenzyme (composed of a regulatory sub-unit, Ku, and a catalytic sub-unit, DNA-PKcs) that assembles at sites of DNA damage. We demonstrated here that the activity of DNA-PK was increased by twofold in two independent radioresistant cell lines, HeLa 3A and CAPAN A3, over expressing the 24 kDa FGF-2. This increase was associated with an overexpression of the DNA-PKcs without modification of Ku expression or activity. This overexpression was due to an up-regulation of the DNA-PKcs gene transcription by the 24 kDa FGF-2 isoform. Finally, HeLa 3A cells exhibited the hallmarks of phenotypic changes associated with the overexpression of an active DNA-PKcs. Indeed, a faster repair rate of DSB and sensitization to IR by wortmannin was observed in these cells. Our results represent the characterization of a new mechanism of control of DNA repair and radioresistance in human tumor cells dependent on the overproduction of the 24 kDa FGF-2 isoform.
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Affiliation(s)
- Isabelle Ader
- Oncologie Cellulaire et Moléculaire, INSERM U563, Département d'Innovation thérapeutique et Oncologie Moléculaire, Centre de Lutte Contre le Cancer Claudius Regaud, 20-24 rue du Pont St Pierre, 31052 Toulouse Cedex France
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15
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Dalenc F, Drouet J, Ader I, Delmas C, Rochaix P, Favre G, Cohen-Jonathan E, Toulas C. Increased expression of a COOH-truncated nucleophosmin resulting from alternative splicing is associated with cellular resistance to ionizing radiation in HeLa cells. Int J Cancer 2002; 100:662-8. [PMID: 12209603 DOI: 10.1002/ijc.10558] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We previously demonstrated that transfecting HeLa cells with the 24 kDa basic fibroblast growth factor-2 (FGF-2) isoform dramatically increased cell survival after irradiation. To investigate genes implicated in this radioresistance acquisition, we compared mRNA expression between radioresistant 24 kDa FGF-2-expressing cells (HeLa 3A) and radiosensitive control HeLa PINA cells using the differential display technique. Of the 32 differentially expressed mRNAs, 1 presented a significant homology with a known gene. This 378 bp fragment presented 100% identity with exon 11 and 12 of human nucleophosmin (NPM) but differed by including a part of intron 9 in its 5' end. The differential expression of this fragment was confirmed using an RNase protection assay. We then cloned the entire corresponding mRNA and showed that it contained all the exons of NPM plus intron 9, suggesting that it was a splicing product of the NPM gene. This variant encoded for a 35-amino acid truncated NPM (NPM2). NPM2 expression was increased in HeLa 3A. To investigate NPM2's role in radioresistance acquisition, we transfected HeLa cells with NPM2 cDNA and analyzed survival after irradiation of the clones obtained. After transfection with NPM2, radiosensitive HeLa cells exhibited a dramatic increase in cell survival after irradiation. Taken together, our results demonstrate that expression of a COOH-truncated NPM form resulting from the alternative splicing of NPM mRNA is able to increase cell survival after irradiation and suggests that it might be involved in cellular response to ionizing radiation.
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Affiliation(s)
- Florence Dalenc
- Laboratoire d'Oncologie Cellulaire et Moléculaire, UPRES-EA 2048, Université Paul Sabatier, Toulouse, France
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16
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Futamura M, Kamiya S, Tsukamoto M, Hirano A, Monden Y, Arakawa H, Nishimura S. Malolactomycin D, a potent inhibitor of transcription controlled by the Ras responsive element, inhibits Ras-mediated transformation activity with suppression of MMP-1 and MMP-9 in NIH3T3 cells. Oncogene 2001; 20:6724-30. [PMID: 11709707 DOI: 10.1038/sj.onc.1204878] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2001] [Revised: 07/24/2001] [Accepted: 08/01/2001] [Indexed: 01/01/2023]
Abstract
To search for anti-cancer agents, a screening system for Ras signal inhibitors was developed using a NIH3T3 cell line with an introduced reporter gene which is controlled by the Ras-responsive element (RRE). With this screening system, malolactomycin D was identified as a selective inhibitor of transcription from the RRE. This compound was found to preferentially inhibit the anchorage-independent growth rather than the anchorage-dependent growth of Ras-transformed NIH3T3 cells. The expression of matrix metalloproteinases MMP-1 and MMP-9, which have RRE in their promoters, were reduced by treatment with malolactomycin D at the translational and transcriptional levels. Analysis of the activity of mitogen-activated protein (MAP) kinases, which play important roles in transduction of the Ras signal, showed that malolactomycin D inhibits the activation of p38 MAP kinase and Jun N-terminal-kinase (JNK) but not extracellular signal-regulated kinase 1 or 2 (ERK1 or 2). These findings suggest that by inhibiting the pathway that leads to the activation of p38 MAP kinase and JNK, malolactomycin D suppresses the expression of MMPs. Since MMPs play important roles in metastasis and maintenance of the microenvironment of tumor cells, both of which facilitate tumor growth, the inhibition of MMPs by malolactomycin D is believed to contribute to its ability to inhibit Ras-mediated tumorigenesis.
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Affiliation(s)
- M Futamura
- Banyu Tsukuba Research Institute, Okubo 3, Tsukuba 300-2611, Japan
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17
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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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Spencer JA, Misra RP. Expression of the SRF gene occurs through a Ras/Sp/SRF-mediated-mechanism in response to serum growth signals. Oncogene 1999; 18:7319-27. [PMID: 10602487 DOI: 10.1038/sj.onc.1203121] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Serum Response Factor (SRF) plays a central role in the transcriptional response of mammalian cells to a variety of extracellular signals. It is a key regulator of many cellular early response genes which are believed to be involved in cell growth, differentiation, and development. The mechanism by which SRF activates transcription in response to mitogenic agents has been extensively studied, however, less is known about regulation of the SRF gene itself. Previously, we identified distinct regulatory elements in the SRF promoter that play a role in activation, including an ETS domain binding site, an overlapping Sp1/Egr-1 binding site, and two SRF binding sites. We further showed that serum induces the SRF gene by a mechanism that requires an intact SRF binding site, also termed a CArG box. In the present study we demonstrate that in response to stimulation by cells by lysophosphatidic acid (LPA) or whole serum, the SRF promoter is upregulated by a bipartite pathway that requires both an Sp1 factor binding site and the CArG motifs for maximal stimulation. The CArG box-dependent component of this pathway is targeted by Rho mediated signals, and the Sp1 binding site dependent component is targeted by Ras mediated signals.
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Affiliation(s)
- J A Spencer
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, WI 53226, USA
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Miano JM, Berk BC. NAB2: a transcriptional brake for activated gene expression in the vessel wall? THE AMERICAN JOURNAL OF PATHOLOGY 1999; 155:1009-12. [PMID: 10514380 PMCID: PMC1867014 DOI: 10.1016/s0002-9440(10)65200-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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