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Fuller RN, Morcos A, Bustillos JG, Molina DC, Wall NR. Small non-coding RNAs and pancreatic ductal adenocarcinoma: Linking diagnosis, pathogenesis, drug resistance, and therapeutic potential. Biochim Biophys Acta Rev Cancer 2024; 1879:189153. [PMID: 38986720 DOI: 10.1016/j.bbcan.2024.189153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 07/03/2024] [Accepted: 07/05/2024] [Indexed: 07/12/2024]
Abstract
This review comprehensively investigates the intricate interplay between small non-coding RNAs (sncRNAs) and pancreatic ductal adenocarcinoma (PDAC), a devastating malignancy with limited therapeutic options. Our analysis reveals the pivotal roles of sncRNAs in various facets of PDAC biology, spanning diagnosis, pathogenesis, drug resistance, and therapeutic strategies. sncRNAs have emerged as promising biomarkers for PDAC, demonstrating distinct expression profiles in diseased tissues. sncRNA differential expression patterns, often detectable in bodily fluids, hold potential for early and minimally invasive diagnostic approaches. Furthermore, sncRNAs exhibit intricate involvement in PDAC pathogenesis, regulating critical cellular processes such as proliferation, apoptosis, and metastasis. Additionally, mechanistic insights into sncRNA-mediated pathogenic pathways illuminate novel therapeutic targets and interventions. A significant focus of this review is dedicated to unraveling sncRNA mechanisms underlying drug resistance in PDAC. Understanding these mechanisms at the molecular level is imperative for devising strategies to overcome drug resistance. Exploring the therapeutic landscape, we discuss the potential of sncRNAs as therapeutic agents themselves as their ability to modulate gene expression with high specificity renders them attractive candidates for targeted therapy. In summary, this review integrates current knowledge on sncRNAs in PDAC, offering a holistic perspective on their diagnostic, pathogenic, and therapeutic relevance. By elucidating the roles of sncRNAs in PDAC biology, this review provides valuable insights for the development of novel diagnostic tools and targeted therapeutic approaches, crucial for improving the prognosis of PDAC patients.
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Affiliation(s)
- Ryan N Fuller
- Department of Basic Science, Division of Biochemistry, Center for Health Disparity and Mol. Med., Loma Linda University, Loma Linda, CA 92350, USA; Department of Radiation Medicine, James M. Slater, MD Proton Treatment and Research Center, Loma Linda University, Loma Linda, CA 92350, USA
| | - Ann Morcos
- Department of Basic Science, Division of Biochemistry, Center for Health Disparity and Mol. Med., Loma Linda University, Loma Linda, CA 92350, USA; Department of Radiation Medicine, James M. Slater, MD Proton Treatment and Research Center, Loma Linda University, Loma Linda, CA 92350, USA
| | - Joab Galvan Bustillos
- Department of Basic Science, Division of Biochemistry, Center for Health Disparity and Mol. Med., Loma Linda University, Loma Linda, CA 92350, USA; Division of Surgical Oncology, Department of Surgery, Loma Linda University, Loma Linda, CA 92350, USA
| | - David Caba Molina
- Division of Surgical Oncology, Department of Surgery, Loma Linda University, Loma Linda, CA 92350, USA
| | - Nathan R Wall
- Department of Basic Science, Division of Biochemistry, Center for Health Disparity and Mol. Med., Loma Linda University, Loma Linda, CA 92350, USA; Department of Radiation Medicine, James M. Slater, MD Proton Treatment and Research Center, Loma Linda University, Loma Linda, CA 92350, USA.
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Wang L, Chen X, Yan C. Ferroptosis: An emerging therapeutic opportunity for cancer. Genes Dis 2022; 9:334-346. [PMID: 35224150 PMCID: PMC8843872 DOI: 10.1016/j.gendis.2020.09.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/16/2020] [Accepted: 09/21/2020] [Indexed: 01/17/2023] Open
Abstract
Ferroptosis, a new form of non-apoptotic, regulated cell death characterized by iron dependency and lipid peroxidation, is involved in many pathological conditions such as neurodegenerative diseases, heart ischemia/reperfusion injury, acute renal failure, and cancer. While metabolic dysfunctions can lead to excessive lipid peroxidation culminating in ferroptotic cell death, glutathione peroxidase 4 (GPX4) resides in the center of a network that functions to prevent lipid hydroperoxides from accumulation, thereby suppressing ferroptosis. Indeed, RSL3 and other small-molecule GPX4 inhibitors can induce ferroptosis in not only cultured cancer cells but also tumor xenografts implanted in mice. Similarly, erastin and other system Xc- inhibitors can deplete intracellular glutathione required for GPX4 function, leading to lipid peroxidation and ferroptosis. As therapy-resistant cancer cells are sensitive to GPX4-targeted therapeutic regimens, the agents capable of inducing ferroptosis hold great promises to improve current cancer therapy. This review will outline the molecular basis of ferroptosis, but focus on the strategies and the agents developed in recent years for therapeutic induction of ferroptosis. The potentials of these ferroptosis-inducing agents, which include system Xc- inhibitors, GPX4 inhibitors, and iron-based nanoparticles, in cancer therapy will be subsequently discussed.
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Affiliation(s)
- Liyuan Wang
- Georgia Cancer Center, Augusta University, Augusta, GA 30912, USA
- Department of Pharmacology, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100050, China
- Department of Pharmacy, Peking University Third Hospital, Beijing 100191, China
| | - Xiaoguang Chen
- Department of Pharmacology, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100050, China
| | - Chunhong Yan
- Georgia Cancer Center, Augusta University, Augusta, GA 30912, USA
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
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ATF3 promotes erastin-induced ferroptosis by suppressing system Xc .. Cell Death Differ 2019; 27:662-675. [PMID: 31273299 PMCID: PMC7206049 DOI: 10.1038/s41418-019-0380-z] [Citation(s) in RCA: 394] [Impact Index Per Article: 78.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 06/15/2019] [Accepted: 06/18/2019] [Indexed: 12/11/2022] Open
Abstract
The amino acid antiporter system Xc− is important for the synthesis of glutathione (GSH) that functions to prevent lipid peroxidation and protect cells from nonapoptotic, iron-dependent death (i.e., ferroptosis). While the activity of system Xc− often positively correlates with the expression level of its light chain encoded by SLC7A11, inhibition of system Xc− activity by small molecules (e.g., erastin) causes a decrease in the intracellular GSH level, leading to ferroptotic cell death. How system Xc− is regulated during ferroptosis remains largely unknown. Here we report that activating transcription factor 3 (ATF3), a common stress sensor, can promote ferroptosis induced by erastin. ATF3 suppressed system Xc−, depleted intracellular GSH, and thereby promoted lipid peroxidation induced by erastin. ATF3 achieved this activity through binding to the SLC7A11 promoter and repressing SLC7A11 expression in a p53-independent manner. These findings thus add ATF3 to a short list of proteins that can regulate system Xc− and promote ferroptosis repressed by this antiporter.
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Carew NT, Nelson AM, Liang Z, Smith SM, Milcarek C. Linking Endoplasmic Reticular Stress and Alternative Splicing. Int J Mol Sci 2018; 19:ijms19123919. [PMID: 30544499 PMCID: PMC6321306 DOI: 10.3390/ijms19123919] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 12/16/2022] Open
Abstract
RNA splicing patterns in antibody-secreting cells are shaped by endoplasmic reticulum stress, ELL2 (eleven-nineteen lysine-rich leukemia gene 2) induction, and changes in the levels of snRNAs. Endoplasmic reticulum stress induces the unfolded protein response comprising a highly conserved set of genes crucial for cell survival; among these is Ire1, whose auto-phosphorylation drives it to acquire a regulated mRNA decay activity. The mRNA-modifying function of phosphorylated Ire1 non-canonically splices Xbp1 mRNA and yet degrades other cellular mRNAs with related motifs. Naïve splenic B cells will activate Ire1 phosphorylation early on after lipopolysaccharide (LPS) stimulation, within 18 h; large-scale changes in mRNA content and splicing patterns result. Inhibition of the mRNA-degradation function of Ire1 is correlated with further differences in the splicing patterns and a reduction in the mRNA factors for snRNA transcription. Some of the >4000 splicing changes seen at 18 h after LPS stimulation persist into the late stages of antibody secretion, up to 72 h. Meanwhile some early splicing changes are supplanted by new splicing changes introduced by the up-regulation of ELL2, a transcription elongation factor. ELL2 is necessary for immunoglobulin secretion and does this by changing mRNA processing patterns of immunoglobulin heavy chain and >5000 other genes.
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Affiliation(s)
- Nolan T Carew
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
| | - Ashley M Nelson
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
| | - Zhitao Liang
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
| | - Sage M Smith
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
| | - Christine Milcarek
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
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Schulten HJ, Bangash M, Karim S, Dallol A, Hussein D, Merdad A, Al-Thoubaity FK, Al-Maghrabi J, Jamal A, Al-Ghamdi F, Choudhry H, Baeesa SS, Chaudhary AG, Al-Qahtani MH. Comprehensive molecular biomarker identification in breast cancer brain metastases. J Transl Med 2017; 15:269. [PMID: 29287594 PMCID: PMC5747948 DOI: 10.1186/s12967-017-1370-x] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 12/18/2017] [Indexed: 01/09/2023] Open
Abstract
Background Breast cancer brain metastases (BCBM) develop in about 20–30% of breast cancer (BC) patients. BCBM are associated with dismal prognosis not at least due to lack of valuable molecular therapeutic targets. The aim of the study was to identify new molecular biomarkers and targets in BCBM by using complementary state-of-the-art techniques. Methods We compared array expression profiles of three BCBM with 16 non-brain metastatic BC and 16 primary brain tumors (prBT) using a false discovery rate (FDR) p < 0.05 and fold change (FC) > 2. Biofunctional analysis was conducted on the differentially expressed probe sets. High-density arrays were employed to detect copy number variations (CNVs) and whole exome sequencing (WES) with paired-end reads of 150 bp was utilized to detect gene mutations in the three BCBM. Results The top 370 probe sets that were differentially expressed between BCBM and both BC and prBT were in the majority comparably overexpressed in BCBM and included, e.g. the coding genes BCL3, BNIP3, BNIP3P1, BRIP1, CASP14, CDC25A, DMBT1, IDH2, E2F1, MYCN, RAD51, RAD54L, and VDR. A number of small nucleolar RNAs (snoRNAs) were comparably overexpressed in BCBM and included SNORA1, SNORA2A, SNORA9, SNORA10, SNORA22, SNORA24, SNORA30, SNORA37, SNORA38, SNORA52, SNORA71A, SNORA71B, SNORA71C, SNORD13P2, SNORD15A, SNORD34, SNORD35A, SNORD41, SNORD53, and SCARNA22. The top canonical pathway was entitled, role of BRCA1 in DNA damage response. Network analysis revealed key nodes as Akt, ERK1/2, NFkB, and Ras in a predicted activation stage. Downregulated genes in a data set that was shared between BCBM and prBT comprised, e.g. BC cell line invasion markers JUN, MMP3, TFF1, and HAS2. Important cancer genes affected by CNVs included TP53, BRCA1, BRCA2, ERBB2, IDH1, and IDH2. WES detected numerous mutations, some of which affecting BC associated genes as CDH1, HEPACAM, and LOXHD1. Conclusions Using complementary molecular genetic techniques, this study identified shared and unshared molecular events in three highly aberrant BCBM emphasizing the challenge to detect new molecular biomarkers and targets with translational implications. Among new findings with the capacity to gain clinical relevance is the detection of overexpressed snoRNAs known to regulate some critical cellular functions as ribosome biogenesis. Electronic supplementary material The online version of this article (10.1186/s12967-017-1370-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hans-Juergen Schulten
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia.
| | - Mohammed Bangash
- Division of Neurosurgery, Department of Surgery, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
| | - Sajjad Karim
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ashraf Dallol
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Deema Hussein
- King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Adnan Merdad
- Department of Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Fatma K Al-Thoubaity
- Department of Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Jaudah Al-Maghrabi
- Department of Pathology, Faculty of Medicine, King Abdulaziz University Hospital, Jeddah, Saudi Arabia.,Department of Pathology, King Faisal Specialist Hospital and Research Center, Jeddah, Saudi Arabia
| | - Awatif Jamal
- Department of Pathology, Faculty of Medicine, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
| | - Fahad Al-Ghamdi
- Department of Pathology, Faculty of Medicine, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
| | - Hani Choudhry
- Biochemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Saleh S Baeesa
- Division of Neurosurgery, Department of Surgery, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
| | - Adeel G Chaudhary
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mohammed H Al-Qahtani
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
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Anwar D, Takahashi H, Watanabe M, Suzuki M, Fukuda S, Hatakeyama S. p53 represses the transcription of snRNA genes by preventing the formation of little elongation complex. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:975-82. [PMID: 27268141 DOI: 10.1016/j.bbagrm.2016.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/12/2016] [Accepted: 06/02/2016] [Indexed: 12/11/2022]
Abstract
The regulation of transcription by RNA polymerase II (Pol II) is important for a variety of cellular functions. ELL/EAF-containing little elongation complex (LEC) was found to be required for transcription of Pol II-dependent small nuclear RNA (snRNA) genes. It was shown that the tumor suppressor p53 interacts with ELL and inhibits transcription elongation activity of ELL. Here, we show that p53 inhibits interaction between ELL/EAF and ICE1 in LEC and thereby p53 represses transcription of Pol II-dependent snRNA genes through inhibiting LEC function. Furthermore, induction of p53 expression by ultraviolet (UV) irradiation decreases the occupancy of ICE1 at Pol II-dependent snRNA genes. Consistent with the results, knockdown of p53 increased both the expression of snRNA genes and the occupancy of Pol II and components of LEC at snRNA genes. Our results indicate that p53 interferes with the interaction between ELL/EAF and ICE1 and represses transcription of snRNA genes by Pol II.
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Affiliation(s)
- Delnur Anwar
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan; Department of Otolaryngology, Head & Neck Surgery, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Hidehisa Takahashi
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Masashi Watanabe
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Masanobu Suzuki
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan; Department of Otolaryngology, Head & Neck Surgery, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Satoshi Fukuda
- Department of Otolaryngology, Head & Neck Surgery, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Shigetsugu Hatakeyama
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan.
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de Las Heras-Rubio A, Perucho L, Paciucci R, Vilardell J, LLeonart ME. Ribosomal proteins as novel players in tumorigenesis. Cancer Metastasis Rev 2015; 33:115-41. [PMID: 24375388 DOI: 10.1007/s10555-013-9460-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ribosome biogenesis is the most demanding energetic and metabolic expenditure of the cell. The nucleolus, a nuclear compartment, coordinates rRNA transcription, maturation, and assembly into ribosome subunits. The transcription process is highly coordinated with ribosome biogenesis. In this context, ribosomal proteins (RPs) play a crucial role. In the last decade, an increasing number of studies have associated RPs with extraribosomal functions related to proliferation. Importantly, the expression of RPs appears to be deregulated in several human disorders due, at least in part, to genetic mutations. Although the deregulation of RPs in human malignancies is commonly observed, a more complex mechanism is believed to be involved, favoring the tumorigenic process, its progression and metastasis. This review explores the roles of the most frequently mutated oncogenes and tumor suppressor genes in human cancer that modulate ribosome biogenesis, including their interaction with RPs. In this regard, we propose a new focus for novel therapies.
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Affiliation(s)
- A de Las Heras-Rubio
- Oncology and Pathology Group, Institut de Recerca Hospital Vall d'Hebron, Passeig Vall d'Hebron 119-129, 08035, Barcelona, Spain
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Liu C, Li S, Dai X, Ma J, Wan J, Jiang H, Wang P, Liu Z, Zhang H. PRC2 regulates RNA polymerase III transcribed non-translated RNA gene transcription through EZH2 and SUZ12 interaction with TFIIIC complex. Nucleic Acids Res 2015; 43:6270-84. [PMID: 26038315 PMCID: PMC4513857 DOI: 10.1093/nar/gkv574] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 05/20/2015] [Indexed: 11/12/2022] Open
Abstract
Polycomb repression complex 2 (PRC2) component EZH2 tri-methylates H3K27 and exerts epigenetic repression on target gene expression. EZH2-mediated epigenetic control of RNA polymerase II (Pol II) transcribed coding gene transcription has been well established. However, little is known about EZH2-mediated epigenetic regulation of RNA polymerase III (Pol III) transcription. Here we present a paradigm that EZH2 is involved in the repression of Pol III transcription via interaction with transcriptional factor complex IIIC (TFIIIC). EZH2 and H3K27me3 co-occupy the promoter of tRNATyr, 5S rRNA and 7SL RNA genes. Depletion of EZH2 or inhibition of EZH2 methyltransferase activity led to upregulation of Pol III target gene transcription. EZH2-mediated repression of Pol III transcribed gene expression requires presence of SUZ12. SUZ12 was able to interact with TFIIIC complex and knockdown of SUZ12 decreased occupancy of EZH2 and H3K27me3 at the promoter of Pol III target genes. Our findings pointed out a previously unidentified role of PRC2 complex in suppressing transcription of Pol III transcribed non-translated RNA genes, putting Pol III on a new layer of epigenetic regulation.
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Affiliation(s)
- Chang Liu
- Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China Laboratory of Molecular Cell Biology and Tumor Biology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China
| | - Shuai Li
- Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China Laboratory of Molecular Cell Biology and Tumor Biology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China
| | - Xiaoyan Dai
- Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China Laboratory of Molecular Cell Biology and Tumor Biology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China
| | - Ji Ma
- Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China Laboratory of Molecular Cell Biology and Tumor Biology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China
| | - Junhu Wan
- Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China Laboratory of Molecular Cell Biology and Tumor Biology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China
| | - Hao Jiang
- Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China Laboratory of Molecular Cell Biology and Tumor Biology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China
| | - Peng Wang
- Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China Laboratory of Molecular Cell Biology and Tumor Biology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China
| | - Zhaoli Liu
- Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China Laboratory of Molecular Cell Biology and Tumor Biology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China
| | - Hongquan Zhang
- Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China Laboratory of Molecular Cell Biology and Tumor Biology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, #38 Xue Yuan Road, Beijing 100191, China
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Rohira AD, Chen CY, Allen JR, Johnson DL. Covalent small ubiquitin-like modifier (SUMO) modification of Maf1 protein controls RNA polymerase III-dependent transcription repression. J Biol Chem 2013; 288:19288-95. [PMID: 23673667 DOI: 10.1074/jbc.m113.473744] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RNA polymerase (pol) III transcribes genes that determine biosynthetic capacity. Induction of these genes is required for oncogenic transformation. The transcriptional repressor, Maf1, plays a central role in the repression of these and other genes that promote oncogenesis. Our studies identify an important new role for SUMOylation in repressing RNA pol III-dependent transcription. We show that a key mechanism by which this occurs is through small ubiquitin-like modifier (SUMO) modification of Maf1 by both SUMO1 and SUMO2. Mutation of each lysine residue revealed that Lys-35 is the major SUMOylation site on Maf1 and that the deSUMOylase, SENP1, is responsible for controlling Maf1K35 SUMOylation. SUMOylation of Maf1 is unaffected by rapamycin inhibition of mammalian target of rapamycin (mTOR) and mTOR-dependent Maf1 phosphorylation. By preventing SUMOylation at Lys-35, Maf1 is impaired in its ability to both repress transcription and suppress colony growth. Although SUMOylation does not alter Maf1 subcellular localization, Maf1K35R is defective in its ability to associate with RNA pol III. This impairs Maf1 recruitment to tRNA gene promoters and its ability to facilitate the dissociation of RNA pol III from these promoters. These studies identify a novel role for SUMOylation in controlling Maf1 and RNA pol III-mediated transcription. Given the emerging roles of SENP1, Maf1, and RNA pol III transcription in oncogenesis, our studies support the idea that deSUMOylation of Maf1 and induction of its gene targets play a critical role in cancer development.
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Affiliation(s)
- Aarti D Rohira
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California and the Norris Comprehensive Cancer Center, Los Angeles, California 90033, USA
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10
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Requirement for SNAPC1 in transcriptional responsiveness to diverse extracellular signals. Mol Cell Biol 2012; 32:4642-50. [PMID: 22966203 DOI: 10.1128/mcb.00906-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Initiation of transcription of RNA polymerase II (RNAPII)-dependent genes requires the participation of a host of basal transcription factors. Among genes requiring RNAPII for transcription, small nuclear RNAs (snRNAs) display a further requirement for a factor known as snRNA-activating protein complex (SNAPc). The scope of the biological function of SNAPc and its requirement for transcription of protein-coding genes has not been elucidated. To determine the genome-wide occupancy of SNAPc, we performed chromatin immunoprecipitation followed by high-throughput sequencing using antibodies against SNAPC4 and SNAPC1 subunits. Interestingly, while SNAPC4 occupancy was limited to snRNA genes, SNAPC1 chromatin residence extended beyond snRNA genes to include a large number of transcriptionally active protein-coding genes. Notably, SNAPC1 occupancy on highly active genes mirrored that of elongating RNAPII extending through the bodies and 3' ends of protein-coding genes. Inhibition of transcriptional elongation resulted in the loss of SNAPC1 from the 3' ends of genes, reflecting a functional association between SNAPC1 and elongating RNAPII. Importantly, while depletion of SNAPC1 had a small effect on basal transcription, it diminished the transcriptional responsiveness of a large number of genes to two distinct extracellular stimuli, epidermal growth factor (EGF) and retinoic acid (RA). These results highlight a role for SNAPC1 as a general transcriptional coactivator that functions through elongating RNAPII.
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11
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Selvakumar T, Gjidoda A, Hovde SL, Henry RW. Regulation of human RNA polymerase III transcription by DNMT1 and DNMT3a DNA methyltransferases. J Biol Chem 2012; 287:7039-50. [PMID: 22219193 DOI: 10.1074/jbc.m111.285601] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human small nuclear RNA (snRNA) and small cytoplasmic RNA (scRNA) gene families encode diverse non-coding RNAs that influence cellular growth and division. Many snRNA and scRNA genes are related via their compact and yet powerful promoters that support RNA polymerase III transcription. We have utilized the human U6 snRNA gene family to examine the mechanism for regulated transcription of these potent transcription units. Analysis of nine U6 family members showed enriched CpG density within the promoters of actively transcribed loci relative to inert genes, implying a relationship between gene potency and DNA methylation. Indeed, both pharmacological inhibition of DNA methyltransferase (DNMT) activity and the forced diminution of DNMT-1, DNMT-3a, and DNMT-3b by siRNA targeting resulted in increased U6 levels in asynchronously growing MCF7 adenocarcinoma cells. In vitro transcription assays further showed that template methylation impedes U6 transcription by RNA polymerase III. Both DNMT-1 and DNMT-3a were detected at the U6-1 locus by chromatin immunoprecipitation directly linking these factors to RNA polymerase III regulation. Despite this association, the endogenous U6-1 locus was not substantially methylated in actively growing cells. However, both DNMT occupancy and low frequency methylation were correlated with increased Retinoblastoma tumor suppressor (RB) expression, suggesting that the RB status can influence specific epigenetic marks.
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Affiliation(s)
- Tharakeswari Selvakumar
- Cell and Molecular Biology Program, Michigan State University, East Lansing, Michigan 48824, USA
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12
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p53 Interacts with RNA polymerase II through its core domain and impairs Pol II processivity in vivo. PLoS One 2011; 6:e22183. [PMID: 21829606 PMCID: PMC3150338 DOI: 10.1371/journal.pone.0022183] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 06/20/2011] [Indexed: 11/25/2022] Open
Abstract
The tumor suppressor p53 principally functions as a gene-specific transcription factor. p53 triggers a variety of anti-proliferative programs by activating or repressing the transcription of effector genes in response to genotoxic stress. To date, much effort has been placed on understanding p53's ability to affect transcription in the context of its DNA-binding activity. How p53 regulates transcriptional output independent of DNA binding is less well understood. Here we provide evidence that human p53 can physically interact with the large subunit of RNA polymerase II (Pol II) both in in vitro interaction assays and in whole cell extracts, and that this interaction is mediated (at least in part) through p53's core DNA-binding domain and the Ser5-phosphorylated CTD of Pol II. Ectopic expression of p53, combined with mutations in transcription elongation factors or exposure to drugs that inhibit Pol II elongation, elicit sickness or lethality in yeast cells. These phenotypes are suppressed by oncogenic point mutations within p53's core domain. The growth phenotypes raise the possibility that p53 impairs Pol II elongation. Consistent with this, a p53-dependent increase in Pol II density is seen at constitutively expressed genes without a concomitant increase in transcript accumulation. Additionally, p53-expressing yeast strains exhibit reduced transcriptional processivity at an episomal reporter gene; this inhibitory activity is abolished by a core domain point mutation. Our results suggest a novel mechanism by which p53 can regulate gene transcription, and a new biological function for its core domain that is susceptible to inactivation by oncogenic point mutations.
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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: 4.1] [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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14
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One function--multiple mechanisms: the manifold activities of p53 as a transcriptional repressor. J Biomed Biotechnol 2011; 2011:464916. [PMID: 21436991 PMCID: PMC3062963 DOI: 10.1155/2011/464916] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 01/17/2011] [Indexed: 12/31/2022] Open
Abstract
Maintenance of genome integrity is a dynamic process involving complex regulation systems. Defects in one or more of these pathways could result in cancer. The most important tumor-suppressor is the transcription factor p53, and its functional inactivation is frequently observed in many tumor types. The tumor suppressive function of p53 is mainly attributed to its ability to regulate numerous target genes at the transcriptional level. While the mechanism of transcriptional induction by p53 is well characterized, p53-dependent repression is not understood in detail. Here, we review the manifold mechanisms of p53 as a transcriptional repressor. We classify two different categories of repressed genes based on the underlying mechanism, and novel mechanisms which involve regulation through noncoding RNAs are discussed. The complete elucidation of p53 functions is important for our understanding of its tumor-suppressor activity and, therefore, represents the key for the development of novel therapeutic approaches.
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15
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Boulon S, Westman BJ, Hutten S, Boisvert FM, Lamond AI. The nucleolus under stress. Mol Cell 2010; 40:216-27. [PMID: 20965417 PMCID: PMC2987465 DOI: 10.1016/j.molcel.2010.09.024] [Citation(s) in RCA: 764] [Impact Index Per Article: 54.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 08/16/2010] [Accepted: 09/22/2010] [Indexed: 12/16/2022]
Abstract
Cells typically respond quickly to stress, altering their metabolism to compensate. In mammalian cells, stress signaling usually leads to either cell-cycle arrest or apoptosis, depending on the severity of the insult and the ability of the cell to recover. Stress also often leads to reorganization of nuclear architecture, reflecting the simultaneous inhibition of major nuclear pathways (e.g., replication and transcription) and activation of specific stress responses (e.g., DNA repair). In this review, we focus on how two nuclear organelles, the nucleolus and the Cajal body, respond to stress. The nucleolus senses stress and is a central hub for coordinating the stress response. We review nucleolar function in the stress-induced regulation of p53 and the specific changes in nucleolar morphology and composition that occur upon stress. Crosstalk between nucleoli and CBs is also discussed in the context of stress responses.
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Affiliation(s)
- Séverine Boulon
- Wellcome Trust Centre for Gene Regulation and Expression, University of Dundee, Dundee DD1 5EH, UK
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16
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Abstract
Inactivation of p53 is critical for the formation of most tumors. Illumination of the key function(s) of p53 protein in protecting cells from becoming cancerous is therefore a worthy goal. Arguably p53's most important function is to act as a transcription factor that directly regulates perhaps several hundred of the cell's RNA polymerase II (RNAP II)-transcribed genes, and indirectly regulates thousands of others. Indeed p53 is the most well studied mammalian transcription factor. The p53 tetramer binds to its response element where it can recruit diverse transcriptional coregulators such as histone modifying enzymes, chromatin remodeling factors, subunits of the mediator complex, and components of general transcription machinery and preinitiation complex (PIC) to modulate RNAPII activity at target loci (Laptenko and Prives 2006). The p53 transcriptional program is regulated in a stimulus-specific fashion (Murray-Zmijewski et al. 2008; Vousden and Prives 2009), whereby distinct subsets of p53 target genes are induced in response to different p53-activating agents, likely allowing cells to tailor their response to different types of stress. How p53 is able to discriminate between these different loci is the subject of intense research. Here, we describe key aspects of the fundamentals of p53-mediated transcriptional regulation and target gene promoter selectivity.
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Affiliation(s)
- Rachel Beckerman
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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17
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Abstract
RNA transcription by all the three RNA polymerases (RNAPs) is tightly controlled, and loss of regulation can lead to, for example, cellular transformation and cancer. While most transcription factors act specifically with one polymerase, a small number have been shown to affect more than one polymerase to coordinate overall levels of transcription in cells. Here we show that TLS (translocated in liposarcoma), a protein originally identified as the product of a chromosomal translocation and which associates with both RNAP II and the spliceosome, also represses transcription by RNAP III. TLS was found to repress transcription from all three classes of RNAP III promoters in vitro and to associate with RNAP III genes in vivo, perhaps via a direct interaction with the pan-specific transcription factor TATA-binding protein (TBP). Depletion of TLS by small interfering RNA (siRNA) in HeLa cells resulted in increased steady-state levels of RNAP III transcripts as well as increased RNAP III and TBP occupancy at RNAP III-transcribed genes. Conversely, overexpression of TLS decreased accumulation of RNAP III transcripts. These unexpected findings indicate that TLS regulates both RNAPs II and III and supports the possibility that cross-regulation between RNA polymerases is important in maintaining normal cell growth.
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18
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Mukherjee S, Manna S, Mukherjee P, Panda CK. Differential alterations in metabolic pattern of the spliceosomal uridylic acid-rich small nuclear RNAs (UsnRNAs) during malignant transformation of 20-methylcholanthrene-induced mouse CNCI-PM-20 embryonic fibroblasts. Mol Carcinog 2009; 48:773-8. [PMID: 19496104 DOI: 10.1002/mc.20556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Differential alterations of the spliceosomal Uridylic acid rich small nuclear RNAs (UsnRNAs) (U1, U2, U4, U5, and U6) are reported to be associated with cellular proliferation and development, but definitive information is scarce and also elusive. An attempt is made in this study to analyze the metabolic patterns of major spliceosomal UsnRNAs, during tumor development, in an in vitro carcinogenesis model of 20-methylcholanthrene (MCA)-transformed Swiss Mouse Embryonic Fibroblast (MEF), designated as CNCI-PM-20. MEF cells, after treatment with 20-MCA, progressed through a sequence of passages with distinct and heritable changes, finally becoming neoplastic at passage-42 (P42). A differential expression pattern of major UsnRNAs was observed during this process. The abundance of U1 was 20% below control (P1) at passage-20 (P20), followed by a gradual increase up until P42 (approximately 12% above the P1 value). The abundance of U2 was more or less constant during the cellular transformation. U4 showed a trend of increase, with above 30% abundance than control at P20, followed by a significant increase at P36 and P42 (1.5- and 2-fold, respectively, P-value <0.01). U5 also followed an identical pattern, with an increase of 70% compared to control (P-value <0.05) at P42. Interestingly, U6 gradually decreased from P20 onwards up until P42, with 22% at P20 and 67% at P42 (P-value <0.01). An overall significant quantitative alteration in abundance of U4, U5, and U6, observed in our study, contributes to the understanding of the fact that, the metabolism of major spliceosomal UsnRNAs is differentially regulated during the process of neoplastic transformation.
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Affiliation(s)
- Sudeshna Mukherjee
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, Kolkata 700026, India
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19
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Barsotti AM, Prives C. Pro-proliferative FoxM1 is a target of p53-mediated repression. Oncogene 2009; 28:4295-305. [PMID: 19749794 DOI: 10.1038/onc.2009.282] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The p53 tumor suppressor protein acts as a transcription factor to modulate cellular responses to a wide variety of stresses. In this study we show that p53 is required for the downregulation of FoxM1, an essential transcription factor that regulates many G2/M-specific genes and is overexpressed in a multitude of solid tumors. After DNA damage, p53 facilitates the repression of FoxM1 mRNA, which is accompanied by a decrease in FoxM1 protein levels. In cells with reduced p53 expression, FoxM1 is upregulated after DNA damage. Nutlin, a small-molecule activator of p53, suppresses FoxM1 levels in two cell lines in which DNA damage facilitates only mild repression. Mechanistically, p53-mediated inhibition of FoxM1 is partially p21 and retinoblastoma (Rb) family dependent, although in some cases p21-independent repression of FoxM1 was also observed. The importance of FoxM1 to cell fate was indicated by the observation that G2/M arrest follows FoxM1 ablation. Finally, our results indicate a potential contribution of p53-mediated repression of FoxM1 for maintenance of a stable G2 arrest.
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Affiliation(s)
- A M Barsotti
- Department of Biological Sciences, Columbia University, New York, NY, USA
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20
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RNA polymerases I and III, non-coding RNAs and cancer. Trends Genet 2008; 24:622-9. [PMID: 18980784 DOI: 10.1016/j.tig.2008.10.003] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 10/06/2008] [Accepted: 10/06/2008] [Indexed: 12/12/2022]
Abstract
Oncogenically transformed cells overexpress the non-coding RNAs, such as pre-ribosomal RNA (rRNA) and transfer RNA (tRNA), which are produced by RNA polymerases (Pols) I and III. Recent results indicate that levels of pre-rRNA have prognostic value and that a tRNA has oncogenic potential. Transcription by Pols I and III is restrained in healthy cells by the tumour suppressors RB, p53, ARF and PTEN. Such restraints are compromised during cell transformation and the problem is accentuated by oncogene products, such as c-Myc, that stimulate the output of Pol I and Pol III. The resultant increases in rRNA and tRNA expression might promote the generation of cancers.
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21
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Jawdekar GW, Henry RW. Transcriptional regulation of human small nuclear RNA genes. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1779:295-305. [PMID: 18442490 PMCID: PMC2684849 DOI: 10.1016/j.bbagrm.2008.04.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Revised: 04/01/2008] [Accepted: 04/02/2008] [Indexed: 01/06/2023]
Abstract
The products of human snRNA genes have been frequently described as performing housekeeping functions and their synthesis refractory to regulation. However, recent studies have emphasized that snRNA and other related non-coding RNA molecules control multiple facets of the central dogma, and their regulated expression is critical to cellular homeostasis during normal growth and in response to stress. Human snRNA genes contain compact and yet powerful promoters that are recognized by increasingly well-characterized transcription factors, thus providing a premier model system to study gene regulation. This review summarizes many recent advances deciphering the mechanism by which the transcription of human snRNA and related genes are regulated.
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Affiliation(s)
- Gauri W. Jawdekar
- Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, CA 90095
| | - R. William Henry
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824
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22
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PTEN represses RNA polymerase III-dependent transcription by targeting the TFIIIB complex. Mol Cell Biol 2008; 28:4204-14. [PMID: 18391023 DOI: 10.1128/mcb.01912-07] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
PTEN, a tumor suppressor whose function is frequently lost in human cancers, possesses a lipid phosphatase activity that represses phosphatidylinositol 3-kinase (PI3K) signaling, controlling cell growth, proliferation, and survival. The potential for PTEN to regulate the synthesis of RNA polymerase (Pol) III transcription products, including tRNAs and 5S rRNAs, was evaluated. The expression of PTEN in PTEN-deficient cells repressed RNA Pol III transcription, whereas decreased PTEN expression enhanced transcription. Transcription repression by PTEN was uncoupled from PTEN-mediated effects on the cell cycle and was independent of p53. PTEN acts through its lipid phosphatase activity, inhibiting the PI3K/Akt/mTOR/S6K pathway to decrease transcription. PTEN, through the inactivation of mTOR, targets the TFIIIB complex, disrupting the association between TATA-binding protein and Brf1. Kinetic analysis revealed that PTEN initially induces a decrease in the serine phosphorylation of Brf1, leading to a selective reduction in the occupancy of all TFIIIB subunits on tRNA(Leu) genes, whereas prolonged PTEN expression results in the enhanced serine phosphorylation of Bdp1. Together, these results demonstrate a new class of genes regulated by PTEN through its ability to repress the activation of PI3K/Akt/mTOR/S6K signaling.
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23
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Gu L, Husain-Ponnampalam R, Hoffmann-Benning S, Henry RW. The protein kinase CK2 phosphorylates SNAP190 to negatively regulate SNAPC DNA binding and human U6 transcription by RNA polymerase III. J Biol Chem 2007; 282:27887-96. [PMID: 17670747 DOI: 10.1074/jbc.m702269200] [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] [Indexed: 11/06/2022] Open
Abstract
Human U6 small nuclear RNA gene transcription by RNA polymerase III requires the general transcription factor SNAP(C), which binds to human small nuclear RNA core promoter elements and nucleates pre-initiation complex assembly with the Brf2-TFIIIB complex. Multiple components in this pathway are phosphorylated by the protein kinase CK2, including the Bdp1 subunit of the Brf2-TFIIIB complex, and RNA polymerase III, with negative and positive outcomes for U6 transcription, respectively. However, a role for CK2 phosphorylation of SNAP(C) in U6 transcription has not been defined. In this report, we investigated the role of CK2 in modulating the transcriptional properties of SNAP(C) and demonstrate that within SNAP(C), CK2 phosphorylates the N-terminal half of the SNAP190 subunit at two regions (amino acids 20-63 and 514-545) that each contain multiple CK2 consensus sites. SNAP190 phosphorylation by CK2 inhibits both SNAP(C) DNA binding and U6 transcription activity. Mutational analyses of SNAP190 support a model wherein CK2 phosphorylation triggers an allosteric inhibition of the SNAP190 Myb DNA binding domain.
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Affiliation(s)
- Liping Gu
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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24
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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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25
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Laptenko O, Prives C. Transcriptional regulation by p53: one protein, many possibilities. Cell Death Differ 2007; 13:951-61. [PMID: 16575405 DOI: 10.1038/sj.cdd.4401916] [Citation(s) in RCA: 371] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The p53 tumor suppressor protein is a DNA sequence-specific transcriptional regulator that, in response to various forms of cellular stress, controls the expression of numerous genes involved in cellular outcomes including among others, cell cycle arrest and cell death. Two key features of the p53 protein are required for its transcriptional activities: its ability to recognize and bind specific DNA sequences and to recruit both general and specialized transcriptional co-regulators. In fact, multiple interactions with co-activators and co-repressors as well as with the components of the general transcriptional machinery allow p53 to either promote or inhibit transcription of different target genes. This review focuses on some of the salient features of the interactions of p53 with DNA and with factors that regulate transcription. We discuss as well the complexities of the functional domains of p53 with respect to these interactions.
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Affiliation(s)
- O Laptenko
- Department of Biological Sciences, Columbia University, 530 120th Street, New York, NY 10027, USA
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26
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Morton JP, Kantidakis T, White RJ. RNA polymerase III transcription is repressed in response to the tumour suppressor ARF. Nucleic Acids Res 2007; 35:3046-52. [PMID: 17439968 PMCID: PMC1888803 DOI: 10.1093/nar/gkm208] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The tumour suppressor protein ARF provides a defence mechanism against hyperproliferative stresses that can result from the aberrant activation of oncogenes. Accordingly, ARF is silenced or deleted in many human cancers. Activation of ARF can arrest growth and cell cycle progression, or trigger apoptosis. A principle mediator of these effects is p53, which ARF stabilizes by binding and inhibiting MDM2. However, ARF has additional targets and remains able to block growth in the absence of p53, albeit less efficiently. For example, ARF can suppress rRNA production in a p53-independent manner. We have found that the synthesis of tRNA by RNA polymerase III is also inhibited in response to ARF. However, in contrast to its effects on rRNA synthesis, ARF is unable to inhibit tRNA gene transcription when p53 is ablated. These results add to the growing list of cellular changes that can be triggered by ARF induction.
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Affiliation(s)
- Jennifer P. Morton
- Institute of Biomedical and Life Sciences, Division of Biochemistry and Molecular Biology, University of Glasgow, Glasgow G12 8QQ and Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Theodoros Kantidakis
- Institute of Biomedical and Life Sciences, Division of Biochemistry and Molecular Biology, University of Glasgow, Glasgow G12 8QQ and Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Robert J. White
- Institute of Biomedical and Life Sciences, Division of Biochemistry and Molecular Biology, University of Glasgow, Glasgow G12 8QQ and Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- *To whom correspondence should be addressed. +44 141 330 3953+44 141 942 6521
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27
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Manna S, Banerjee S, Mukherjee S, Das S, Panda CK. Epigallocatechin gallate induced apoptosis in Sarcoma180 cells in vivo: mediated by p53 pathway and inhibition in U1B, U4-U6 UsnRNAs expression. Apoptosis 2007; 11:2267-76. [PMID: 17041754 DOI: 10.1007/s10495-006-0198-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The aim of this study was to understand the mode of action of tea polyphenol epigallocatechin gallate (EGCG) in vivo. Swiss albino mice were treated i.p. with EGCG at two different doses i.e. 12-mg/kg body weight and 15-mg/kg body weight, for 7 days prior to inoculation of Sarcoma180 (S180) cells and continued for another 7 days. The growth of the S180, harvested 7 days after inoculation, was significantly reduced due to treatment with EGCG. The flowcytometric analysis of S180 cells, showed significant increase in apoptosis and reduction in the number of cells in G2/M phase of cell cycle due to treatment with EGCG. The induction of apoptosis has also been confirmed by the TUNEL and DNA fragmentation assays. Both RT-PCR and Western blot analysis showed significant up-regulation of p53 and bax, and down-regulation of bcl-2 and c-myc due to EGCG treatment. No changes in the expression pattern of p21, p27, bcl-xl, mdm2 and cyclin D1 were seen. Interestingly, there was significant down-regulation of spliceosomal uridylic acid rich small nuclear RNAs (UsnRNAs) U1B and U4-U6 due to EGCG treatment. This indicates that these UsnRNAs may be involved in the apoptosis process. Taken together, our study suggests that in vivo EGCG could induce apoptosis in S180 cells through alteration in G2/M phase of the cell cycle by up-regulation of p53, bax and down-regulation of c-myc, bcl-2 and U1B, U4-U6 UsnRNAs.
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Affiliation(s)
- Sugata Manna
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata, 700026, India
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Reina JH, Azzouz TN, Hernandez N. Maf1, a new player in the regulation of human RNA polymerase III transcription. PLoS One 2006; 1:e134. [PMID: 17205138 PMCID: PMC1762419 DOI: 10.1371/journal.pone.0000134] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 12/05/2006] [Indexed: 11/18/2022] Open
Abstract
Background Human RNA polymerase III (pol III) transcription is regulated by several factors, including the tumor suppressors P53 and Rb, and the proto-oncogene c-Myc. In yeast, which lacks these proteins, a central regulator of pol III transcription, called Maf1, has been described. Maf1 is required for repression of pol III transcription in response to several signal transduction pathways and is broadly conserved in eukaryotes. Methodology/Principal Findings We show that human endogenous Maf1 can be co-immunoprecipitated with pol III and associates in vitro with two pol III subunits, the largest subunit RPC1 and the α-like subunit RPAC2. Maf1 represses pol III transcription in vitro and in vivo and is required for maximal pol III repression after exposure to MMS or rapamycin, treatments that both lead to Maf1 dephosphorylation. Conclusions/Significance These data suggest that Maf1 is a major regulator of pol III transcription in human cells.
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29
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Manna S, Banerjee S, Saha P, Roy A, Das S, Panda CK. Differential Alterations in Metabolic Pattern of the Spliceosomal UsnRNAs during Pre-Malignant Lung Lesions Induced by Benzo(a)pyrene: Modulation by Tea Polyphenols. Mol Cell Biochem 2006; 289:149-57. [PMID: 16718374 DOI: 10.1007/s11010-006-9158-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Accepted: 02/14/2006] [Indexed: 10/24/2022]
Abstract
The differential alterations of the spliceosomal UsnRNAs (U1, U2, U4, U5, and U6) were reported to be associated with cellular proliferation and development. The attempt was made in this study to analyze the metabolic pattern of the spliceosomal UsnRNAs during the development of pre-malignant lung lesions induced in experimental mice model system by benzo(a)pyrene (BP) and also to see how tea polyphenols, epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), modulate the metabolism of these UsnRNAs during the lung carcinogenesis. No significant changes in the level of the UsnRNAs were seen in the inflammatory lung lesions at 9th week due to treatment of BP. However, there was significant increase in the level of U1 ( approximately 2.5 fold) and U5 ( approximately 47%) in the hyperplastic lung lesions at 17th week. But in the mild dysplastic lung lesions at 26th week, the level of UsnRNAs did not change significantly. Whereas, in the dysplastic lung lesions at 36th week there was significant increase in the level of the U2 ( approximately 2 fold), U4 ( approximately 2.5 fold) and U5 ( approximately 2 fold). Due to the EGCG and ECG treatment the lung lesions at 9th week appeared normal and in the 17th, 26th, and 36th week it appeared as hyperplasia. The level of the UsnRNAs was significantly low in the lung lesions at 9th week (only U2 and U4 by EGCG), at 17th week (only U1 by EGCG/ECG), at 26th week (U1 by ECG; U2, U4 and U5 by EGCG/ECG) and at 36th week (U1 by ECG, U2 and U4 by EGCG/ECG). Whereas, there was significant increase in the level of U5 (by EGCG/ECG) and U6 (by EGCG only) in the lung lesions at 36th and 26th week respectively. This indicates that the metabolism of the spliceosomal UsnRNAs differentially altered during the development of pre-malignant lung lesions by BP as well as during the modulation of the lung lesions by the tea polyphenols.
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Affiliation(s)
- Sugata Manna
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata 700026, India
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Hanzlowsky A, Jelencic B, Jawdekar G, Hinkley CS, Geiger JH, Henry RW. Co-expression of multiple subunits enables recombinant SNAPC assembly and function for transcription by human RNA polymerases II and III. Protein Expr Purif 2006; 48:215-23. [PMID: 16603380 PMCID: PMC2714255 DOI: 10.1016/j.pep.2006.02.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 02/07/2006] [Accepted: 02/19/2006] [Indexed: 11/21/2022]
Abstract
Human small nuclear (sn) RNA genes are transcribed by either RNA polymerase II or III depending upon the arrangement of their core promoter elements. Regardless of polymerase specificity, these genes share a requirement for a general transcription factor called the snRNA activating protein complex or SNAP(C). This multi-subunit complex recognizes the proximal sequence element (PSE) commonly found in the upstream promoters of human snRNA genes. SNAP(C) consists of five subunits: SNAP190, SNAP50, SNAP45, SNAP43, and SNAP19. Previous studies have shown that a partial SNAP(C) composed of SNAP190 (1-514), SNAP50, and SNAP43 expressed in baculovirus is capable of PSE-specific DNA binding and transcription of human snRNA genes by RNA polymerases II and III. Expression in a baculovirus system yields active complex but the concentration of such material is insufficient for many bio-analytical methods. Herein, we describe the co-expression in Escherichia coli of a partial SNAP(C) containing SNAP190 (1-505), SNAP50, SNAP43, and SNAP19. The co-expressed complex binds DNA specifically and recruits TBP to U6 promoter DNA. Importantly, this partial complex functions in reconstituted transcription of both human U1 and U6 snRNA genes by RNA polymerases II and III, respectively. This co-expression system will facilitate the functional characterization of this unusual multi-protein transcription factor that plays an important early role for transcription by two different polymerases.
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Affiliation(s)
- Andrej Hanzlowsky
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Blanka Jelencic
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Gauri Jawdekar
- Department of Microbiology and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Craig S. Hinkley
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - James H. Geiger
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
- Corresponding authors. Fax: +1 517 353 9334. E-mail addresses: (J.H. Geiger), (R.W. Henry)
| | - R. William Henry
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
- Corresponding authors. Fax: +1 517 353 9334. E-mail addresses: (J.H. Geiger), (R.W. Henry)
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