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Peng F, Zhou Y, Wang J, Guo B, Wei Y, Deng H, Wu Z, Zhang C, Shi K, Li Y, Wang X, Shore P, Zhao S, Deng W. The transcription factor Sp1 modulates RNA polymerase III gene transcription by controlling BRF1 and GTF3C2 expression in human cells. J Biol Chem 2020; 295:4617-4630. [PMID: 32115405 DOI: 10.1074/jbc.ra119.011555] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/16/2020] [Indexed: 01/10/2023] Open
Abstract
Specificity protein 1 (Sp1) is an important transcription factor implicated in numerous cellular processes. However, whether Sp1 is involved in the regulation of RNA polymerase III (Pol III)-directed gene transcription in human cells remains unknown. Here, we first show that filamin A (FLNA) represses Sp1 expression as well as expression of TFIIB-related factor 1 (BRF1) and general transcription factor III C subunit 2 (GTF3C2) in HeLa, 293T, and SaOS2 cell lines stably expressing FLNA-silencing shRNAs. Both BRF1 promoter 4 (BRF1P4) and GTF3C2 promoter 2 (GTF3C2P2) contain putative Sp1-binding sites, suggesting that Sp1 affects Pol III gene transcription by regulating BRF1 and GTF3C2 expression. We demonstrate that Sp1 knockdown inhibits Pol III gene transcription, BRF1 and GTF3C2 expression, and the proliferation of 293T and HeLa cells, whereas Sp1 overexpression enhances these activities. We obtained a comparable result in a cell line in which both FLNA and Sp1 were depleted. These results indicate that Sp1 is involved in the regulation of Pol III gene transcription independently of FLNA expression. Reporter gene assays showed that alteration of Sp1 expression affects BRF1P4 and GTF3C2P2 activation, suggesting that Sp1 modulates Pol III-mediated gene transcription by controlling BRF1 and GTF3C2 gene expression. Further analysis revealed that Sp1 interacts with and thereby promotes the occupancies of TATA box-binding protein, TFIIAα, and p300 at both BRF1P4 and GTF3C2P2. These findings indicate that Sp1 controls Pol III-directed transcription and shed light on how Sp1 regulates cancer cell proliferation.
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Affiliation(s)
- Feixia Peng
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Ying Zhou
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Juan Wang
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Baoqiang Guo
- Centre for Bioscience, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester M1 5GD, United Kingdom
| | - Yun Wei
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Huan Deng
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Zihui Wu
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Cheng Zhang
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Kaituo Shi
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Yuan Li
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Xin Wang
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Paul Shore
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Shasha Zhao
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Wensheng Deng
- College of Life Science and Health, Wuhan University of Science and Technology, Wuhan 430065, China
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Cabarcas S, Schramm L. RNA polymerase III transcription in cancer: the BRF2 connection. Mol Cancer 2011; 10:47. [PMID: 21518452 PMCID: PMC3098206 DOI: 10.1186/1476-4598-10-47] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 04/25/2011] [Indexed: 12/13/2022] Open
Abstract
RNA polymerase (pol) III transcription is responsible for the transcription of small, untranslated RNAs involved in fundamental metabolic processes such mRNA processing (U6 snRNA) and translation (tRNAs). RNA pol III transcription contributes to the regulation of the biosynthetic capacity of a cell and a direct link exists between cancer cell proliferation and deregulation of RNA pol III transcription. Accurate transcription by RNA pol III requires TFIIIB, a known target of regulation by oncogenes and tumor suppressors. There have been significant advances in our understanding of how TFIIIB-mediated transcription is deregulated in a variety of cancers. Recently, BRF2, a component of TFIIIB required for gene external RNA pol III transcription, was identified as an oncogene in squamous cell carcinomas of the lung through integrative genomic analysis. In this review, we focus on recent advances demonstrating how BRF2-TFIIIB mediated transcription is regulated by tumor suppressors and oncogenes. Additionally, we present novel data further confirming the role of BRF2 as an oncogene, extracted from the Oncomine database, a cancer microarray database containing datasets derived from patient samples, providing evidence that BRF2 has the potential to be used as a biomarker for patients at risk for metastasis. This data further supports the idea that BRF2 may serve as a potential therapeutic target in a variety of cancers.
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Affiliation(s)
- Stephanie Cabarcas
- National Cancer Institute, Laboratory of Cancer Prevention, Cancer Stem Cell Section, 1050 Boyles Street, Building 560, Room 21-81, Frederick, MD 21702, USA
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Mahoney SJ, Dempsey JM, Blenis J. Cell signaling in protein synthesis ribosome biogenesis and translation initiation and elongation. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 90:53-107. [PMID: 20374739 DOI: 10.1016/s1877-1173(09)90002-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Protein synthesis is a highly energy-consuming process that must be tightly regulated. Signal transduction cascades respond to extracellular and intracellular cues to phosphorylate proteins involved in ribosomal biogenesis and translation initiation and elongation. These phosphorylation events regulate the timing and rate of translation of both specific and total mRNAs. Alterations in this regulation can result in dysfunction and disease. While many signaling pathways intersect to control protein synthesis, the mTOR and MAPK pathways appear to be key players. This chapter briefly reviews the mTOR and MAPK pathways and then focuses on individual phosphorylation events that directly control ribosome biogenesis and translation.
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Affiliation(s)
- Sarah J Mahoney
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Dieci G, Fiorino G, Castelnuovo M, Teichmann M, Pagano A. The expanding RNA polymerase III transcriptome. Trends Genet 2007; 23:614-22. [PMID: 17977614 DOI: 10.1016/j.tig.2007.09.001] [Citation(s) in RCA: 391] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 09/14/2007] [Accepted: 09/17/2007] [Indexed: 11/19/2022]
Abstract
The role of RNA polymerase (Pol) III in eukaryotic transcription is commonly thought of as being restricted to a small set of highly expressed, housekeeping non-protein-coding (nc)RNA genes. Recent studies, however, have remarkably expanded the set of known Pol III-synthesized ncRNAs, suggesting that gene-specific Pol III regulation is more common than previously appreciated. Newly identified Pol III transcripts include small nucleolar RNAs, microRNAs, short interspersed nuclear element-encoded or tRNA-derived RNAs and novel classes of ncRNA that can display significant sequence complementarity to protein-coding genes and might thus regulate their expression. The extent of the Pol III transcriptome, the complexity of its regulation and its influence on cell physiology, development and disease are emerging as new areas for future research.
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Affiliation(s)
- Giorgio Dieci
- Dipartimento di Biochimica e Biologia Molecolare, Università degli Studi di Parma, Viale G.P. Usberti 23/A, 43100 Parma, Italy.
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Zhou D, Zhong S, Ye JJ, Quach KM, Johnson DL, Chen S. PNRC is a unique nuclear receptor coactivator that stimulates RNA polymerase III-dependent transcription. J Mol Signal 2007; 2:5. [PMID: 17612402 PMCID: PMC1939705 DOI: 10.1186/1750-2187-2-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Accepted: 07/05/2007] [Indexed: 02/08/2023] Open
Abstract
Background PNRC transcriptionally regulates a wide range of RNA polymerase (pol) II-transcribed genes by functioning as a nuclear receptor coactivator. To search for additional PNRC-interacting proteins other than nuclear receptors, a PNRC fragment was used as bait in a yeast two-hybrid screening of a human mammary gland cDNA expression library. Results RNA pol III/RPC39 fragments were repeatedly identified as PNRC-interacting partners in two independent screenings. The interaction between these RPC39 fragments and PNRC was further confirmed in the independent yeast two-hybrid assays. The association of endogenous PNRC and RPC39 in MCF7 cells was demonstrated by co-immunoprecipitation. Furthermore, ChIP analysis detected co-recruitment of PNRC and RPC39 to tRNA and U6 RNA promoters. The biological consequence of the interaction between PNRC and RPC39 was further studied. Overexpression of PNRC, either by transient or stable transfection, increased RNA pol III-dependent transcription in MCF7 cells, while a decrease in transcription in MCF7 cells treated with PNRC/siRNA was observed. Conclusion Here, we demonstrate that human PNRC stimulates RNA pol III transcription through its interaction with the subunit RPC39 of RNA pol III. PNRC is a unique coactivator that has profound effects on many aspects of cellular function by directly influencing both RNA pol II- and RNA pol III-dependent transcription.
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Affiliation(s)
- Dujin Zhou
- Department of Surgical Research, Beckman Research Institute of City of Hope, 1450 East Duarte Road, Duarte, CA 91010, USA
| | - Shuping Zhong
- Department of Biochemistry and Molecular Biology, Keck School of Medicine and Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90033, USA
| | - Jing-Jing Ye
- Department of Surgical Research, Beckman Research Institute of City of Hope, 1450 East Duarte Road, Duarte, CA 91010, USA
| | - Keith M Quach
- Department of Surgical Research, Beckman Research Institute of City of Hope, 1450 East Duarte Road, Duarte, CA 91010, USA
| | - Deborah L Johnson
- Department of Biochemistry and Molecular Biology, Keck School of Medicine and Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90033, USA
| | - Shiuan Chen
- Department of Surgical Research, Beckman Research Institute of City of Hope, 1450 East Duarte Road, Duarte, CA 91010, USA
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Hatzfeld M. Plakophilins: Multifunctional proteins or just regulators of desmosomal adhesion? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:69-77. [PMID: 16765467 DOI: 10.1016/j.bbamcr.2006.04.009] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 04/11/2006] [Accepted: 04/19/2006] [Indexed: 01/11/2023]
Abstract
Plakophilins 1-3 are members of the p120(ctn) family of armadillo-related proteins. The plakophilins have been characterized as desmosomal proteins, whereas p120(ctn) and the closely related delta-catenin, ARVCF and p0071 associate with adherens junctions and play essential roles in stabilizing cadherin mediated adhesion. Recent evidence suggests that plakophilins are essential components of the desmosomal plaque where they interact with desmosomal cadherins as well as the cytoskeletal linker protein desmoplakin. Plakophilins stabilize desmosomal proteins at the plasma membrane and therefore may function in a manner similar to p120(ctn) in the adherens junctions. The three plakophilins reveal distinct expression patterns, and although partially redundant in their function, mediate distinct effects on desmosomal adhesion. Besides a structural role, a function in signaling has been postulated in analogy to other armadillo proteins such as beta-catenin. At least plakophilins 1 and 2 are also localized in the nucleus, and all three proteins occur in a cytoplasmic pool. This review aims to summarize the current knowledge of plakophilin function in the context of cell adhesion, signaling and their putative role in diseases.
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Affiliation(s)
- Mechthild Hatzfeld
- Institute of Pathophysiology, Division of Pathobiochemistry, University of Halle, Hollystrasse 1, 06097 Halle, Germany.
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