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Dehghani A, Khajepour F, Dehghani M, Razmara E, Zangouey M, Abadi MFS, Nezhad RBA, Dabiri S, Garshasbi M. Hsa-miR-194-5p and hsa-miR-195-5p are down-regulated expressed in high dysplasia HPV-positive Pap smear samples compared to normal cytology HPV-positive Pap smear samples. BMC Infect Dis 2024; 24:182. [PMID: 38342922 PMCID: PMC10860252 DOI: 10.1186/s12879-023-08942-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 12/20/2023] [Indexed: 02/13/2024] Open
Abstract
BACKGROUND The human papillomavirus (HPV) infection may affect the miRNA expression pattern during cervical cancer (CC) development. To demonstrate the association between high-risk HPVs and the development of cervix dysplasia, we examined the expression patterns of hsa-miR-194-5p and hsa-miR-195-5p in Pap smear samples from southeast Iranian women. We compared samples that were HPV-positive but showed no abnormality in the cytological examination to samples that were HPV-positive and had severe dysplasia. METHODS Pap smear samples were obtained from 60 HPV-positive (HPV-16/18) patients with histologically confirmed severe dysplasia (cervical intra-epithelial neoplasia (CIN 3) or carcinoma in situ) and the normal cytology group. The expression of hsa-miR-194-5p and hsa-miR-195-5p was analyzed by real-time quantitative PCR, using specific stem-loop primers and U6 snRNA as the internal reference gene. Clinicopathological features were associated with miRNA expression levels. Furthermore, functional enrichment analysis was conducted using in silico tools. The Kaplan-Meier survival method was also obtained to discriminate survival-significant candidate miRNAs in CC, and receiver operating characteristic (ROC) curves were constructed to assess the diagnostic value. RESULTS Compared to HPV-positive cytologically normal Pap smear samples, hsa-miR-194-5p and hsa-miR-195-5p relative expression decreased significantly in HPV-positive patients with a severe dysplasia Pap smear. Kaplan-Meier analysis indicated a significant association between the miR-194 decrease and poor CC survival. In essence, ROC curve analysis showed that miR-194-5p and miR-195-5p could serve as valuable markers for the development of cervix dysplasia in individuals who are positive for high-risk HPVs. CONCLUSIONS This study revealed that hsa-miR-194-5p and hsa-miR-195-5p may possess tumor suppressor capabilities in the context of cervical dysplasia progression. However, it remains uncertain whether these microRNAs are implicated in the transition of patients with high dysplasia to cervical cancer. We also showed the potential capability of candidate miRNAs as novel diagnostic biomarkers related to cervical dysplasia progression.
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Affiliation(s)
- Ali Dehghani
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Fardin Khajepour
- Department of Immunology, Afzalipour Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohammad Dehghani
- Pathology and Stem Cell Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Ehsan Razmara
- Australian Regenerative Medicine Institute, Monash University, Melbourne, Australia
| | - Mohammadreza Zangouey
- Pathology and Stem Cell Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | | | - Reza Bahram Abadi Nezhad
- Department of Microbiology, School of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Shahriar Dabiri
- Pathology and Stem Cell Research Center, Kerman University of Medical Sciences, Kerman, Iran.
| | - Masoud Garshasbi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
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Del Vecchio A, Mulé P, Fernández-Pérez D, Amato S, Lattanzi G, Zanotti M, Rustichelli S, Pivetti S, Oldani P, Mariani A, Iommazzo F, Koseki H, Facciotti F, Tamburri S, Ferrari KJ, Pasini D. PCGF6 controls murine Tuft cell differentiation via H3K9me2 modification independently of Polycomb repression. Dev Cell 2024; 59:368-383.e7. [PMID: 38228142 DOI: 10.1016/j.devcel.2023.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 10/01/2023] [Accepted: 12/21/2023] [Indexed: 01/18/2024]
Abstract
Cell fate is determined by specific transcription programs that are essential for tissue homeostasis and regeneration. The E3-ligases RING1A and B represent the core activity of the Polycomb repressive complex 1 (PRC1) that deposits repressive histone H2AK119 mono-ubiquitination (H2AK119ub1), which is essential for mouse intestinal homeostasis by preserving stem cell functions. However, the specific role of different PRC1 forms, which are defined by the six distinct PCGF1-6 paralogs, remains largely unexplored in vivo. We report that PCGF6 regulates mouse intestinal Tuft cell differentiation independently of H2AK119ub1 deposition. We show that PCGF6 chromatin occupancy expands outside Polycomb repressive domains, associating with unique promoter and distal regulatory elements. This occurs in the absence of RING1A/B and involves MGA-mediated E-BOX recognition and specific H3K9me2 promoter deposition. PCGF6 inactivation induces an epithelial autonomous accumulation of Tuft cells that was not phenocopied by RING1A/B loss. This involves direct PCGF6 association with a Tuft cell differentiation program that identified Polycomb-independent properties of PCGF6 in adult tissues homeostasis.
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Affiliation(s)
- Annachiara Del Vecchio
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Patrizia Mulé
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Daniel Fernández-Pérez
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Simona Amato
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Georgia Lattanzi
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Marika Zanotti
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Samantha Rustichelli
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Silvia Pivetti
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Paola Oldani
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Andrea Mariani
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Fabiola Iommazzo
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Haruhiko Koseki
- RIKEN Centre for Integrative Medical Sciences, Laboratory for Developmental Genetics, 1-7-22 Suehiuro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Federica Facciotti
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy; University of Milano-Bicocca, Department of Biotechnology and Biosciences, Piazza della Scienza, 2, 20126 Milan, Italy
| | - Simone Tamburri
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy; University of Milan, Department of Health Sciences, Via A. di Rudinì 8, 20142 Milan, Italy
| | - Karin J Ferrari
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Diego Pasini
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy; University of Milan, Department of Health Sciences, Via A. di Rudinì 8, 20142 Milan, Italy.
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3
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Wu Z, Su J, Li FL, Chen T, Mayner J, Engler A, Ma S, Li Q, Guan KL. YAP silencing by RB1 mutation is essential for small-cell lung cancer metastasis. Nat Commun 2023; 14:5916. [PMID: 37739954 PMCID: PMC10516997 DOI: 10.1038/s41467-023-41585-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 09/07/2023] [Indexed: 09/24/2023] Open
Abstract
Small cell lung cancer (SCLC) is highly lethal due to its prevalent metastasis. Most SCLCs have inactivating mutations in TP53 and RB1. We find that loss of YAP expression is key for SCLC cells to acquire rapid ameboid migration and high metastatic potential. YAP functions through its target genes CCN1/CCN2 to inhibit SCLC ameboid migration. RB1 mutation contributes to YAP transcriptional silencing via E2F7, which recruits the RCOR co-repressor complex to YAP promoter. We discover that benzamide family HDAC inhibitors stimulate YAP expression by inhibiting the RCOR-HDAC complex, thereby suppressing SCLC metastasis and improving survival in a mouse model. Our study unveils the molecular and cellular basis underlying SCLC's high metastatic potential, the previously unrecognized role of YAP in suppressing ameboid migration and tumor metastasis, and the mechanism of YAP transcription regulation involving E2F7, RCOR, and Sin3 HDAC. This study reveals a therapeutic potential of benzamides for SCLC treatment.
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Affiliation(s)
- Zhengming Wu
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Junhui Su
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, 201203, China
| | - Fu-Long Li
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Tao Chen
- Endoscopy Center, Department of Gastroenterology, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, 200120, China
| | - Jaimie Mayner
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Adam Engler
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Shenghong Ma
- Wellcome Sanger Institute, Cambridge, CB10 1RQ, UK
| | - Qingquan Li
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, 201203, China.
| | - Kun-Liang Guan
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA, 92093, USA.
- School of Life Sciences, Westlake University, Hangzhou, 310030, China.
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Huang Y, Chen Z, Lu T, Bi G, Li M, Liang J, Hu Z, Zheng Y, Yin J, Xi J, Lin Z, Zhan C, Jiang W, Wang Q, Tan L. HIF-1α switches the functionality of TGF-β signaling via changing the partners of smads to drive glucose metabolic reprogramming in non-small cell lung cancer. J Exp Clin Cancer Res 2021; 40:398. [PMID: 34930376 PMCID: PMC8690885 DOI: 10.1186/s13046-021-02188-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 11/19/2021] [Indexed: 02/20/2023] Open
Abstract
BACKGROUND Most cancer cells have fundamentally different metabolic characteristics, particularly much higher glycolysis rates than normal tissues, which support the increased demand for biosynthesis and promote tumor progression. We found that transforming growth factor (TGF)-β plays a dual function in regulating glycolysis and cell proliferation in non-small cell lung cancer. METHODS We used the PET/MRI imaging system to observe the glucose metabolism of subcutaneous tumors in nude mice. Energy metabolism of non-small cell lung cancer cell lines detected by the Seahorse XFe96 cell outflow analyzer. Co-immunoprecipitation assays were used to detect the binding of Smads and HIF-1α. Western blotting and qRT-PCR were used to detect the regulatory effects of TGF-β and HIF-1α on c-MYC, PKM1/2, and cell cycle-related genes. RESULTS We discovered that TGF-β could inhibit glycolysis under normoxia while significantly promoting tumor cells' glycolysis under hypoxia in vitro and in vivo. The binding of hypoxia-inducible factor (HIF)-1α to the MH2 domain of phosphorylated Smad3 switched TGF-β function to glycolysis by changing Smad partners under hypoxia. The Smad-p107-E2F4/5 complex that initially inhibited c-Myc expression was transformed into a Smad-HIF-1α complex that promoted the expression of c-Myc. The increased expression of c-Myc promoted alternative splicing of PKM to PKM2, resulting in the metabolic reprogramming of tumor cells. In addition, the TGF-β/Smad signal lost its effect on cell cycle regulatory protein p15/p21. Furthermore, high expression of c-Myc inhibited p15/p21 and promoted the proliferation of tumor cells under hypoxia. CONCLUSIONS Our results indicated that HIF-1α functions as a critical factor in the dual role of TGF-β in tumor cells, and may be used as a biomarker or therapeutic target for TGF-β mediated cancer progression.
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Affiliation(s)
- Yiwei Huang
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Zhencong Chen
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Tao Lu
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Guoshu Bi
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Ming Li
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Jiaqi Liang
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Zhengyang Hu
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Yuansheng Zheng
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Jiacheng Yin
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Junjie Xi
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Zongwu Lin
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Cheng Zhan
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China.
| | - Wei Jiang
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China.
| | - Qun Wang
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
| | - Lijie Tan
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, 200032, Shanghai, China
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Identification and characterization of distinct cell cycle stages in cardiomyocytes using the FUCCI transgenic system. Exp Cell Res 2021; 408:112880. [PMID: 34655601 DOI: 10.1016/j.yexcr.2021.112880] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/07/2021] [Accepted: 10/10/2021] [Indexed: 11/20/2022]
Abstract
Understanding the regulatory mechanism by which cardiomyocyte proliferation transitions to endoreplication and cell cycle arrest during the neonatal period is crucial for identifying proproliferative factors and developing regenerative therapies. We used a transgenic mouse model based on the fluorescent ubiquitination-based cell cycle indicator (FUCCI) system to isolate and characterize cycling cardiomyocytes at different cell cycle stages at a single-cell resolution. Single-cell transcriptome analysis of cycling and noncycling cardiomyocytes was performed at postnatal days 0 (P0) and 7 (P7). The FUCCI system proved to be efficient for the identification of cycling cardiomyocytes with the highest mitotic activity at birth, followed by a gradual decline in the number of cycling and mitotic cardiomyocytes during the neonatal period. Cardiomyocytes showed premature cell cycle exit at G1/S shortly after birth and delayed G1/S progression during endoreplication at P7. Single-cell RNA-seq confirmed previously described signaling pathways involved in cardiomyocyte proliferation (Erbb2 and Hippo/YAP), and maturation-related transcriptional changes during postnatal development, including the metabolic switch from glycolysis to fatty acid oxidation in cardiomyocytes. Importantly, we generated transcriptional profiles specific to cell division and endoreplication in cardiomyocytes at different developmental stages that may facilitate the identification of genes important for adult cardiomyocyte proliferation and heart regeneration. In conclusion, the FUCCI mouse provides a valuable system to study cardiomyocyte cell cycle activity at single cell resolution that can help to decipher the switch from cardiomyocyte proliferation to endoreplication, and to revert this process to facilitate endogenous repair.
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6
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Jing T, Wang B, Yang Z, Liu Y, Xu G, Xu X, Jiao K, Chen Z, Xiang L, Zhang L, Liu Y. Deubiquitination of the repressor E2F6 by USP22 facilitates AKT activation and tumor growth in hepatocellular carcinoma. Cancer Lett 2021; 518:266-277. [PMID: 34339800 DOI: 10.1016/j.canlet.2021.07.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 07/16/2021] [Accepted: 07/28/2021] [Indexed: 01/20/2023]
Abstract
Dysregulated ubiquitination of tumor-related proteins plays a critical role in tumor development and progression. The deubiquitinase USP22 is aberrantly expressed in certain types of cancer and contributes to aggressive tumor progression. However, the precise mechanism underlying the pro-tumorigenic function of USP22 in hepatocellular carcinoma (HCC) remains unclear. Here, we report that E2F6, a pocket protein-independent transcription repressor, is essential for HCC cell growth, and that its activities are controlled by USP22-mediated deubiquitination. USP22 interacts with and stabilizes E2F6, resulting in the transcriptional repression of phosphatase DUSP1. Moreover, the process involving DUSP1 repression by E2F6 strengthens AKT activation in HCC cells. Therefore, these findings provide mechanistic insights into the USP22-mediated control of oncogenic AKT signaling, emphasizing the importance of USP22-E2F6 regulation in HCC development.
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Affiliation(s)
- Tiantian Jing
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200240, China
| | - Boshi Wang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200240, China
| | - Zhaojuan Yang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200240, China
| | - Yun Liu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200240, China
| | - Guiqin Xu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200240, China
| | - Xiaoli Xu
- Shanghai Jiao Tong University School of Biomedical Engineering, Shanghai, 200030, China
| | - Kun Jiao
- Shanghai Jiao Tong University School of Biomedical Engineering, Shanghai, 200030, China
| | - Zehong Chen
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200240, China
| | - Lvzhu Xiang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200240, China
| | - Li Zhang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200240, China.
| | - Yongzhong Liu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200240, China.
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Zheng B, Zhang S, Cai W, Wang J, Wang T, Tang N, Shi Y, Luo X, Yan W. Identification of Novel Fusion Transcripts in Undifferentiated Pleomorphic Sarcomas by Transcriptome Sequencing. Cancer Genomics Proteomics 2020; 16:399-408. [PMID: 31467233 DOI: 10.21873/cgp.20144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/03/2019] [Accepted: 07/04/2019] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND/AIM Undifferentiated pleomorphic sarcoma (UPS) is an aggressive mesenchymal neoplasm characterized by chromosomal instability. The aim of this study was to identify fusion events involved in UPS. MATERIALS AND METHODS Transcriptome sequencing was performed to search for new fusion genes in 19 UPS samples, including two paired recurrent (R) and re-recurrent (RR) samples. RESULTS A total of 66 fusion genes were detected. Among them, 10 novel fusion genes were further confirmed by reverse transcription polymerase chain reaction (RT-PCR) and Sanger sequencing. Retinoblastoma (RB1) fusions (2 cases) were the most recurrent fusion genes. The gene fusions RB1-RNASEH2B, RB1-FGF14-AS1, and E2F6-FKBP4 were correlated with the Rb/E2F pathway. Pseudogenes were involved in the formation of the gene fusions CIC-DUX4L8 and EIF2AK4-ANXA2P2. Importantly, targetable gene fusions (PDGFRA-MACROD2 and NCOR1-MAP2K1) were detected in UPS. CONCLUSION Screening for the presence of fusion transcripts will provide vital clues to the understanding of genetic alterations and the finding of new targeted therapies for UPS.
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Affiliation(s)
- Biqiang Zheng
- Department of Musculoskeletal Cancer Surgery, Fudan University Shanghai Cancer Center, Shanghai, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China
| | | | - Weiluo Cai
- Department of Musculoskeletal Cancer Surgery, Fudan University Shanghai Cancer Center, Shanghai, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China
| | - Jian Wang
- Department of Musculoskeletal Cancer Surgery, Fudan University Shanghai Cancer Center, Shanghai, P.R. China.,Department of Pathology, Fudan University Shanghai Cancer Center, Shanghai, P.R. China
| | - Ting Wang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, P.R. China
| | - Ning Tang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, P.R. China
| | - Yingqiang Shi
- Department of Musculoskeletal Cancer Surgery, Fudan University Shanghai Cancer Center, Shanghai, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China
| | - Xiaoying Luo
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, P.R. China
| | - Wangjun Yan
- Department of Musculoskeletal Cancer Surgery, Fudan University Shanghai Cancer Center, Shanghai, P.R. China .,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China
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Lafta IJ. E2F6 is essential for cell viability in breast cancer cells during replication stress. ACTA ACUST UNITED AC 2019; 43:293-304. [PMID: 31768102 PMCID: PMC6823915 DOI: 10.3906/biy-1905-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
E2F6 is a member of the E2F family of transcription factors involved in regulation of a wide variety of genes through both activation and repression. E2F6 has been reported as overexpressed in breast cancers but whether or not this is important for tumor development is unclear. We first checked E2F6 expression in tumor cDNAs and the protein level in a range of breast cancer cell lines. RNA interference-mediated depletion was then used to assess the importance of E2F6 expression in cell lines with regard to cell cycle profile using fluorescence-activated cell sorting and a cell survival assay using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The overexpression of E2F6 was confirmed in breast tumor cDNA samples and breast cancer cell lines. Depletion of E2F6 in the breast cancer cells reduced cell viability in MCF-7, T-47D, and MDA-MB-231 cells. There was little effect in the nontumor breast cell line MCF-10A. The deleterious effect on cancer cells was greater during replication stress, leading to an increase in the proportion of breast cancer cells with sub-G1 DNA content. These results suggest that E2F6 might be essential for the survival of breast cancer cells experiencing replication stress, and therefore it could be a target for combined therapy.
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Affiliation(s)
- Inam Jasim Lafta
- Department of Microbiology, College of Veterinary Medicine, University of Baghdad, Baghdad, Iraq
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9
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Shi X, Ma D, Li M, Zeng L, Chen J, Yang Y. Nuclear receptor TLX regulates islet beta cell proliferation via E2F6. Biochem Biophys Res Commun 2019; 513:560-566. [PMID: 30981507 DOI: 10.1016/j.bbrc.2019.04.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 04/03/2019] [Indexed: 12/13/2022]
Abstract
Both type 1 and type 2 diabetes are associated with loss of functional beta cell mass, and strategies to restore beta cells are urgently needed. We reported previously that overexpression of the nuclear receptor TLX induces beta cell proliferation, but the underlying molecular mechanism has not been defined. Here, we identified direct targets of TLX in beta cells at the genome-wide level by ChIP-Seq. These targets include a cadre of regulators that are known to be critical for proliferation. Among these ChIP targets, E2F6 was tightly associated with the cell cycle modules, and thus, we further analyzed E2F6 expression and function in beta cells. We showed that E2F6 is strongly downregulated by TLX, and its expression inhibits beta cell proliferation. Moreover, coexpression of E2F6 with TLX partially abrogated the proliferative effects of TLX. These results strongly suggest that TLX acts through E2F6 to regulate beta cell proliferation. Together, the results of this study reveal a direct interaction between TLX and E2F6 and suggest new targets for the expansion of functional beta cell mass.
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Affiliation(s)
- Xiaoli Shi
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, PR China
| | - Delin Ma
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, PR China
| | - Mengni Li
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, PR China
| | - Liwen Zeng
- Department of Endocrinology, Taikang Tongji(Wuhan) Hospital, PR China
| | - Jing Chen
- Department of Endocrinology, Taikang Tongji(Wuhan) Hospital, PR China
| | - Yan Yang
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, PR China.
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Yuan S, Xiang Y, Wang G, Zhou M, Meng G, Liu Q, Hu Z, Li C, Xie W, Wu N, Wu L, Cai T, Ma X, Zhang Y, Yu Z, Bai L, Li Y. Hypoxia-sensitive LINC01436 is regulated by E2F6 and acts as an oncogene by targeting miR-30a-3p in non-small cell lung cancer. Mol Oncol 2019; 13:840-856. [PMID: 30614188 PMCID: PMC6441908 DOI: 10.1002/1878-0261.12437] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 12/10/2018] [Accepted: 12/17/2018] [Indexed: 12/26/2022] Open
Abstract
Dysregulation of long noncoding RNA (lncRNA) is known to be involved in numerous human diseases, including lung cancer. However, the precise biological functions of most lncRNA remain to be elucidated. Here, we identified a novel up‐regulated lncRNA, LINC01436 (RefSeq: NR_110419.1), in non‐small cell lung cancer (NSCLC). High expression of LINC01436 was significantly associated with poor overall survival. Notably, LINC01436 expression was transcriptionally repressed by E2F6 under normoxia, and the inhibitory effect was relieved in a hypoxic microenvironment. Gain‐ and loss‐of‐function studies revealed that LINC01436 acted as a proto‐oncogene by promoting lung cancer cell growth, migration and invasion in vitro. Xenograft tumor assays in nude mice confirmed that LINC01436 promoted tumor growth and metastasis in vivo. Mechanistically, LINC01436 exerted biological functions by acting as a microRNA (miR)‐30a‐3p sponge to regulate the expression of its target gene EPAS1. Our findings characterize LINC01436 as a new hypoxia‐sensitive lncRNA with oncogenic function in NSCLC, suggesting that LINC01436 may be a potential biomarker for prognosis and a potential target for treatment.
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Affiliation(s)
- Shuai Yuan
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Ying Xiang
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Guilu Wang
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China.,Department of Epidemiology, School of Public Health, Guizhou Medical University, China
| | - Meiyu Zhou
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China.,Department of Epidemiology, School of Public Health, Guizhou Medical University, China
| | - Gang Meng
- Department of Pathology, Southwest Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Qingyun Liu
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Zeyao Hu
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Chengying Li
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Weijia Xie
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Na Wu
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Long Wu
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Tongjian Cai
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Xiangyu Ma
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yao Zhang
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Zubin Yu
- Department of Thoracic Surgery, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Li Bai
- Department of Respiratory Disease, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yafei Li
- Department of Epidemiology, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China
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11
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E2F6 protein levels modulate drug induced apoptosis in cardiomyocytes. Cell Signal 2017; 40:230-238. [PMID: 28964969 DOI: 10.1016/j.cellsig.2017.09.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 09/19/2017] [Accepted: 09/26/2017] [Indexed: 12/18/2022]
Abstract
The E2F/Rb pathway regulates cell growth, differentiation, and death. In particular, E2F1 promotes apoptosis in all cells including those of the heart. E2F6, which represses E2F activity, was found to induce dilated cardiomyopathy in the absence of apoptosis in murine post-natal heart. Here we evaluate the anti-apoptotic potential of E2F6 in neonatal cardiomyocytes (NCM) from E2F6-Tg hearts which showed significantly less caspase-3 cleavage, a lower Bax/Bcl2 ratio, and improved cell viability in response to CoCl2 exposure. This correlated with a decrease in the pro-apoptotic E2F3 protein levels. In contrast, no difference in apoptotic markers or cell viability was observed in response to Doxorubicin (Dox) treatment between Wt and Tg-NCM. Dox caused a rapid and dramatic loss of the E2F6 protein in Tg-NCM within 6h and was undetectable after 12h. The level of e2f6 transcript was unchanged in Wt NCM, but was dramatically decreased in Tg cells in response to both Dox and CoCl2. This was related to an impact of the drugs on the α-myosin heavy chain promoter used to drive the E2F6 transgene. By comparison in HeLa, Dox induced apoptosis through upregulation of endogenous E2F1 involving post-transcriptional mechanisms, while E2F6 was down regulated with induction of the Checkpoint kinase-1 and proteasome degradation. These data imply that E2F6 serves to modulate E2F activity and protect cells including cardiomyocytes from apoptosis and improve survival. Strategies to modulate E2F6 levels may be therapeutically useful to mitigate cell death associated disorders.
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12
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Mu W, Starmer J, Shibata Y, Yee D, Magnuson T. EZH1 in germ cells safeguards the function of PRC2 during spermatogenesis. Dev Biol 2017; 424:198-207. [PMID: 28254491 DOI: 10.1016/j.ydbio.2017.02.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Revised: 02/25/2017] [Accepted: 02/26/2017] [Indexed: 12/28/2022]
Abstract
We previously reported the requirement of Polycomb Repressive Complex 2 (PRC2) for spermatogenesis through transcriptional repression of somatic genes and meiosis-specific genes. To characterize how PRC2's two methyltransferase subunits, EZH1 and EZH2, regulate histone H3 lysine 27 (H3K27) methylation during germ cell development, we generated mouse models with a germline ablation of EZH1 and/or EHZ2. Only the combined loss of EZH1 and EZH2 caused a depletion of global H3K27me3 marks and meiotic arrest in spermatocytes. Genome-wide analysis of H3K27me3 in spermatogenic cells revealed that a noncanonical EZH1-PRC2 could establish and maintain this histone mark on somatic genes and certain meiotic genes. Consistent with it having active enhancers in testis, Ezh1 was not only abundant in highly differentiated spermatocytes but also in actively proliferating progenitor and stem germ cells. Taken together, our findings suggest that the expression level of Ezh1 determines the restoration of H3K27 methylation in the absence of the canonical EZH2-PRC2.
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Affiliation(s)
- Weipeng Mu
- Department of Genetics, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7264, USA
| | - Joshua Starmer
- Department of Genetics, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7264, USA
| | - Yoichiro Shibata
- Department of Genetics, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7264, USA
| | - Della Yee
- Department of Genetics, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7264, USA
| | - Terry Magnuson
- Department of Genetics, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7264, USA.
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13
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Pei Y, Banerjee S, Sun Z, Jha HC, Saha A, Robertson ES. EBV Nuclear Antigen 3C Mediates Regulation of E2F6 to Inhibit E2F1 Transcription and Promote Cell Proliferation. PLoS Pathog 2016; 12:e1005844. [PMID: 27548379 PMCID: PMC4993364 DOI: 10.1371/journal.ppat.1005844] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 08/05/2016] [Indexed: 12/15/2022] Open
Abstract
Epstein–Barr virus (EBV) is considered a ubiquitous herpesvirus with the ability to cause latent infection in humans worldwide. EBV-association is evidently linked to different types of human malignancies, mainly of epithelial and lymphoid origin. Of interest is the EBV nuclear antigen 3C (EBNA3C) which is critical for EBV-mediated immortalization. Recently, EBNA3C was shown to bind the E2F1 transcription regulator. The E2F transcription factors have crucial roles in various cellular functions, including cell cycle, DNA replication, DNA repair, cell mitosis, and cell fate. Specifically, E2F6, one of the unique E2F family members, is known to be a pRb-independent transcription repressor of E2F-target genes. In our current study, we explore the role of EBNA3C in regulating E2F6 activities. We observed that EBNA3C plays an important role in inducing E2F6 expression in LCLs. Our study also shows that EBNA3C physically interacts with E2F6 at its amino and carboxy terminal domains and they form a protein complex in human cells. In addition, EBNA3C stabilizes the E2F6 protein and is co-localized in the nucleus. We also demonstrated that both EBNA3C and E2F6 contribute to reduction in E2F1 transcriptional activity. Moreover, E2F1 forms a protein complex with EBNA3C and E2F6, and EBNA3C competes with E2F1 for E2F6 binding. E2F6 is also recruited by EBNA3C to the E2F1 promoter, which is critical for EBNA3C-mediated cell proliferation. These results demonstrate a critical role for E2F family members in EBV-induced malignancies, and provide new insights for targeting E2F transcription factors in EBV-associated cancers as potential therapeutic intervention strategies. EBV is associated with a broad range of human cancers. EBV-encoded nuclear antigen 3C (EBNA3C) is one of the essential latent antigens important for deregulating the functions of numerous host transcription factors which play vital roles in B-cell immortalization. The family of E2F transcription factors are involved in diverse cellular functions. More specifically, E2F6 is one of the E2F family members with a unique property of transcriptional repression. Our current study now demonstrates that EBNA3C can enhance E2F6 repressive functions, and is also responsible for increased E2F6 protein expression in EBV-transformed LCLs. EBNA3C directly interacts with E2F6 at its amino and carboxy terminal domains. Additionally, E2F6 was stabilized by EBNA3C and co-localized in nuclear compartments. Our study also demonstrated that EBNA3C and E2F6 expression resulted in decreased transcriptional activity of E2F1, and that EBNA3C, E2F6 and E2F1 can form a protein complex, and EBNA3C competes with E2F1 for E2F6 binding. The recruitment of E2F6 by EBNA3C was also shown to be important for its related cell proliferation. These results showed a crucial role for EBNA3C-mediated deregulation of E2F6 and its impact on the activities of other E2F family members. Our findings also provide new insights for targeting these E2F transcription factors as potential therapeutic intervention strategies in EBV-associated cancers.
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Affiliation(s)
- Yonggang Pei
- Department of Otorhinolaryngology-Head and Neck Surgery, and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Shuvomoy Banerjee
- Department of Otorhinolaryngology-Head and Neck Surgery, and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Zhiguo Sun
- Department of Otorhinolaryngology-Head and Neck Surgery, and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Hem Chandra Jha
- Department of Otorhinolaryngology-Head and Neck Surgery, and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Abhik Saha
- Department of Biological Sciences, Presidency University, Kolkata, India
| | - Erle S Robertson
- Department of Otorhinolaryngology-Head and Neck Surgery, and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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14
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Castillo DS, Campalans A, Belluscio LM, Carcagno AL, Radicella JP, Cánepa ET, Pregi N. E2F1 and E2F2 induction in response to DNA damage preserves genomic stability in neuronal cells. Cell Cycle 2016; 14:1300-14. [PMID: 25892555 DOI: 10.4161/15384101.2014.985031] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
E2F transcription factors regulate a wide range of biological processes, including the cellular response to DNA damage. In the present study, we examined whether E2F family members are transcriptionally induced following treatment with several genotoxic agents, and have a role on the cell DNA damage response. We show a novel mechanism, conserved among diverse species, in which E2F1 and E2F2, the latter specifically in neuronal cells, are transcriptionally induced after DNA damage. This upregulation leads to increased E2F1 and E2F2 protein levels as a consequence of de novo protein synthesis. Ectopic expression of these E2Fs in neuronal cells reduces the level of DNA damage following genotoxic treatment, while ablation of E2F1 and E2F2 leads to the accumulation of DNA lesions and increased apoptotic response. Cell viability and DNA repair capability in response to DNA damage induction are also reduced by the E2F1 and E2F2 deficiencies. Finally, E2F1 and E2F2 accumulate at sites of oxidative and UV-induced DNA damage, and interact with γH2AX DNA repair factor. As previously reported for E2F1, E2F2 promotes Rad51 foci formation, interacts with GCN5 acetyltransferase and induces histone acetylation following genotoxic insult. The results presented here unveil a new mechanism involving E2F1 and E2F2 in the maintenance of genomic stability in response to DNA damage in neuronal cells.
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Affiliation(s)
- Daniela S Castillo
- a Laboratorio de Biología Molecular; Departamento de Química Biológica; Facultad de Ciencias Exactas y Naturales ; Universidad de Buenos Aires ; Ciudad de Buenos Aires , Argentina
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15
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Thurlings I, de Bruin A. E2F Transcription Factors Control the Roller Coaster Ride of Cell Cycle Gene Expression. Methods Mol Biol 2016; 1342:71-88. [PMID: 26254918 DOI: 10.1007/978-1-4939-2957-3_4] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Initially, the E2F transcription factor was discovered as a factor able to bind the adenovirus E2 promoter and activate viral genes. Afterwards it was shown that E2F also binds to promoters of nonviral genes such as C-MYC and DHFR, which were already known at that time to be important for cell growth and DNA metabolism, respectively. These findings provided the first clues that the E2F transcription factor might be an important regulator of the cell cycle. Since this initial discovery in 1987, several additional E2F family members have been identified, and more than 100 targets genes have been shown to be directly regulated by E2Fs, the majority of these are important for controlling the cell cycle. The progression of a cell through the cell cycle is accompanied with the increased expression of a specific set of genes during one phase of the cell cycle and the decrease of the same set of genes during a later phase of the cell cycle. This roller coaster ride, or oscillation, of gene expression is essential for the proper progression through the cell cycle to allow accurate DNA replication and cell division. The E2F transcription factors have been shown to be critical for the temporal expression of the oscillating cell cycle genes. This review will focus on how the oscillation of E2Fs and their targets is regulated by transcriptional, post-transcriptional and post-translational mechanism in mammals, yeast, flies, and worms. Furthermore, we will discuss the functional impact of E2Fs on the cell cycle progression and outline the consequences when E2F expression is disturbed.
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Affiliation(s)
- Ingrid Thurlings
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL, Utrecht, The Netherlands
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16
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Huo Q, Kayikci M, Odermatt P, Meyer K, Michels O, Saxena S, Ule J, Schümperli D. Splicing changes in SMA mouse motoneurons and SMN-depleted neuroblastoma cells: evidence for involvement of splicing regulatory proteins. RNA Biol 2015; 11:1430-46. [PMID: 25692239 PMCID: PMC4601534 DOI: 10.1080/15476286.2014.996494] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Spinal Muscular Atrophy (SMA) is caused by deletions or mutations in the Survival Motor Neuron 1 (SMN1) gene. The second gene copy, SMN2, produces some, but not enough, functional SMN protein. SMN is essential to assemble small nuclear ribonucleoproteins (snRNPs) that form the spliceosome. However, it is not clear whether SMA is caused by defects in this function that could lead to splicing changes in all tissues, or by the impairment of an additional, less well characterized, but motoneuron-specific SMN function. We addressed the first possibility by exon junction microarray analysis of motoneurons (MNs) isolated by laser capture microdissection from a severe SMA mouse model. This revealed changes in multiple U2-dependent splicing events. Moreover, splicing appeared to be more strongly affected in MNs than in other cells. By testing mutiple genes in a model of progressive SMN depletion in NB2a neuroblastoma cells, we obtained evidence that U2-dependent splicing changes occur earlier than U12-dependent ones. As several of these changes affect genes coding for splicing regulators, this may acerbate the splicing response induced by low SMN levels and induce secondary waves of splicing alterations.
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Key Words
- ESE, exonic splicing enhancer
- FCS, fetal calf serum
- MN, motoneuron
- NMD, nonsense-mediated mRNA decay
- NMJ, neuromuscular junction, PCR
- RT, reverse transcription
- SMA, Spinal Muscular Atrophy
- SMN, Survival Motor Neuron
- Spinal Muscular Atrophy
- TcRβ, T-cell receptor β chain
- exon junction microarray
- hz, heterozygote, LCM
- laser capture microdissection
- major spliceosome
- minor spliceosome
- motoneurons
- neurodegerative disease
- polymerase chain reaction, qPCR
- real-time (quantitative) PCR
- sh, short hairpin
- snRNA, small nuclear ribonucleic acid
- snRNP assembly
- snRNP, small nuclear ribonucleoprotein
- splicing
- splicing regulators
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Affiliation(s)
- Qing Huo
- a Institute of Cell Biology ; University of Bern ; Bern , Switzerland
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17
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Major JL, Salih M, Tuana BS. Interplay between the E2F pathway and β-adrenergic signaling in the pathological hypertrophic response of myocardium. J Mol Cell Cardiol 2015; 84:179-90. [PMID: 25944088 DOI: 10.1016/j.yjmcc.2015.04.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 04/15/2015] [Accepted: 04/29/2015] [Indexed: 12/28/2022]
Abstract
The E2F/Pocket protein (Rb) pathway regulates cell growth, differentiation, and death by modulating gene expression. We previously examined this pathway in the myocardium via manipulation of the unique E2F repressor, E2F6, which is believed to repress gene activity independently of Rb. Mice with targeted expression of E2F6 in postnatal myocardium developed dilated cardiomyopathy (DCM) without hypertrophic growth. We assessed the mechanisms of the apparent failure of compensatory hypertrophic growth as well as their response to the β-adrenergic agonist isoproterenol. As early as 2 weeks, E2F6 transgenic (Tg) mice present with dilated thinner left ventricles and significantly reduced ejection fraction and fractional shortening which persists at 6 weeks of age, but with no apparent increase in left ventricle weight: body weight (LVW:BW). E2F6-Tg mice treated with isoproterenol (6.1 mg/kg/day) show double the increase in LVW:BW than their Wt counterparts (32% vs 16%, p-value: 0.007). Western blot analysis revealed the activation of the adrenergic pathway in Tg heart tissue under basal conditions with ~2-fold increase in the level of β2-adrenergic receptors (p-value: 8.9E-05), protein kinase A catalytic subunit (PKA-C) (p-value: 0.0176), activated c-Src tyrosine-protein kinase (p-value: 0.0002), extracellular receptor kinase 2 (ERK2) (p-value: 0.0005), and induction of the anti-apoptotic protein Bcl2 (p-value 0. 0.00001). In contrast, a ~60% decrease in the cardiac growth regulator: AKT1 (p-value 0.0001) and a ~four fold increase in cyclic AMP dependent phosphodiesterase 4D (PDE4D), the negative regulator of PKA activity, were evident in the myocardium of E2F6-Tg mice. The expression of E2F3 was down-regulated by E2F6, but was restored by isoproterenol. Further, Rb expression was down-regulated in Tg mice in response to isoproterenol implying a net activation of the E2F pathway. Thus the unique regulation of E2F activity by E2F6 renders the myocardium hypersensitive to adrenergic stimulus resulting in robust hypertrophic growth. These data reveal a novel interplay between the E2F pathway, β2-adrenergic/PKA/PDE4D, and ERK/c-Src axis in fine tuning the pathological hypertrophic growth response. E2F6 deregulates E2F3 such that pro-hypertrophic growth and survival are enhanced via β2-adrenergic signaling however this response is outweighed by the induction of anti-hypertrophic signals so that left ventricle dilation proceeds without any increase in muscle mass.
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Affiliation(s)
- Jennifer L Major
- Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada
| | - Maysoon Salih
- Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada
| | - Balwant S Tuana
- Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada; University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario K1Y 4W7, Canada.
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18
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Kanai D, Ueda A, Akagi T, Yokota T, Koide H. Oct3/4 directly regulates expression of E2F3a in mouse embryonic stem cells. Biochem Biophys Res Commun 2015; 459:374-8. [PMID: 25727014 DOI: 10.1016/j.bbrc.2015.02.105] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 02/18/2015] [Indexed: 10/23/2022]
Abstract
Embryonic stem (ES) cells, derived from the inner cell mass of blastocysts, have a characteristic cell cycle with truncated G1 and G2 phases. Recent findings that suppression of Oct3/4 expression results in a reduced proliferation rate of ES cells suggest the involvement of Oct3/4 in the regulation of ES cell growth, although the underlying molecular mechanism remains unclear. In the present study, we identified E2F3a as a direct target gene of Oct3/4 in ES cells. Oct3/4 directly bound to the promoter region of the E2F3a gene and positively regulated expression of E2F3a in mouse ES cells. Suppression of E2F3a activity by E2F6 overexpression led to the reduced proliferation in ES cells, which was relieved by co-expression of E2F3a. Furthermore, cell growth retardation caused by loss of Oct3/4 was rescued by E2F3a expression. These results suggest that Oct3/4 upregulates E2F3a expression to promote ES cell growth.
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Affiliation(s)
- Dai Kanai
- Department of Stem Cell Biology, Graduate School of Medical Sciences, Kanazawa University, Japan
| | - Atsushi Ueda
- Department of Stem Cell Biology, Graduate School of Medical Sciences, Kanazawa University, Japan
| | - Tadayuki Akagi
- Department of Stem Cell Biology, Graduate School of Medical Sciences, Kanazawa University, Japan
| | - Takashi Yokota
- Department of Stem Cell Biology, Graduate School of Medical Sciences, Kanazawa University, Japan
| | - Hiroshi Koide
- Department of Stem Cell Biology, Graduate School of Medical Sciences, Kanazawa University, Japan.
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19
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Regulation of microRNA-mediated gene silencing by microRNA precursors. Nat Struct Mol Biol 2014; 21:825-32. [PMID: 25086740 PMCID: PMC4244528 DOI: 10.1038/nsmb.2862] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 07/01/2014] [Indexed: 11/23/2022]
Abstract
Processing of miRNAs from their precursors to the biologically active mature form is regulated during development and cancer. We show that mouse precursor-miR-151 can bind to and compete with mature miR-151-5p and miR-151-3p for binding sites contained within the complementary regions of the E2f6 mRNA 3′UTR. In agreement, E2f6 mRNA levels were regulated by precursor-miR-151. Conversely, the miR-151-mediated repression of ARHGDIA mRNA was only dependent on the mature miR-151 level as only the mature miRNA was able to bind to the 3′UTR. This suggests that processing of miR-151 can have different effects on separate mRNA targets within a cell. A bioinformatics pipeline revealed additional candidate regions where pre-miRNAs can compete with their mature miRNA counterparts. This was experimentally validated for miR-124 and the SNAI2 3′UTR. Hence, miRNA precursors can serve as post-transcriptional regulators of miRNA activity and are not mere biogenesis intermediates.
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20
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Faisal M, Waseem D, Ismatullah H, Taqi MM. A molecular prospective provides new insights into implication of PDYN and OPRK1 genes in alcohol dependence. Comput Biol Med 2014; 53:250-7. [PMID: 25177835 DOI: 10.1016/j.compbiomed.2014.07.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 07/24/2014] [Accepted: 07/26/2014] [Indexed: 12/15/2022]
Abstract
Single nucleotide polymorphisms (SNPs) both in coding and non-coding regions govern gene functions prompting differential vulnerability to diseases, heterogeneous response to pharmaceutical regimes and environmental anomalies. These genetic variations, SNPs, may alter an individual׳s susceptibility for alcohol dependence by remodeling DNA-protein interaction patterns in prodynorphin (PDYN) and the κ-opioid receptor (OPRK1) genes. In order to elaborate the underlying molecular mechanism behind these susceptibility differences we used bioinformatics tools to retrieve differential DNA-protein interactions at PDYN and OPRK1 SNPs significantly associated with alcohol dependence. Our results show allele-specific DNA-protein interactions depicting allele-specific mechanisms implicated in differential regulation of gene expression. Several transcription factors, for instance, VDR, RXR-alpha, NFYA, CTF family, USF-1, USF2, ER, AR and predominantly SP family show an allele-specific binding affinity with PDYN gene; likewise, GATA, TBP, AP-1, USF-2, C/EBPbeta, Cart-1 and ER interact with OPRK1 SNPs on intron 2 in an allele-specific manner. In a nutshell, transition of a single nucleotide may modify differential DNA-protein interactions at OPRK1 and PDYN׳s SNPs, significantly associated with pathology that may lead to altered individual vulnerability for alcohol dependence.
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Affiliation(s)
- Muhammad Faisal
- National Center for Bioinformatics, Quaid-i-Azam University, Islamabad, Pakistan
| | - Durdana Waseem
- Department of Pharmacy, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Humaira Ismatullah
- Department of Bioinformatics and Biotechnology, International Islamic University, Islamabad, Pakistan
| | - Malik Mumtaz Taqi
- Department of Pharmacy, Quaid-i-Azam University, Islamabad 45320, Pakistan.
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21
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Xiaofei E, Kowalik TF. The DNA damage response induced by infection with human cytomegalovirus and other viruses. Viruses 2014; 6:2155-85. [PMID: 24859341 PMCID: PMC4036536 DOI: 10.3390/v6052155] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 05/02/2014] [Accepted: 05/08/2014] [Indexed: 12/12/2022] Open
Abstract
Viruses use different strategies to overcome the host defense system. Recent studies have shown that viruses can induce DNA damage response (DDR). Many of these viruses use DDR signaling to benefit their replication, while other viruses block or inactivate DDR signaling. This review focuses on the effects of DDR and DNA repair on human cytomegalovirus (HCMV) replication. Here, we review the DDR induced by HCMV infection and its similarities and differences to DDR induced by other viruses. As DDR signaling pathways are critical for the replication of many viruses, blocking these pathways may represent novel therapeutic opportunities for the treatment of certain infectious diseases. Lastly, future perspectives in the field are discussed.
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Affiliation(s)
- E Xiaofei
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, 368 Plantation St, Worcester, MA 01605, USA.
| | - Timothy F Kowalik
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, 368 Plantation St, Worcester, MA 01605, USA.
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22
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Wang X, Choi JH, Ding J, Yang L, Ngoka LC, Lee EJ, Zha Y, Mao L, Jin B, Ren M, Cowell J, Huang S, Shi H, Cui H, Ding HF. HOXC9 directly regulates distinct sets of genes to coordinate diverse cellular processes during neuronal differentiation. BMC Genomics 2013; 14:830. [PMID: 24274069 PMCID: PMC3906982 DOI: 10.1186/1471-2164-14-830] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 11/20/2013] [Indexed: 01/06/2023] Open
Abstract
Background Cellular differentiation is characterized by the acquisition of specialized structures and functions, cell cycle exit, and global attenuation of the DNA damage response. It is largely unknown how these diverse cellular events are coordinated at the molecular level during differentiation. We addressed this question in a model system of neuroblastoma cell differentiation induced by HOXC9. Results We conducted a genome-wide analysis of the HOXC9-induced neuronal differentiation program. Microarray gene expression profiling revealed that HOXC9-induced differentiation was associated with transcriptional regulation of 2,370 genes, characterized by global upregulation of neuronal genes and downregulation of cell cycle and DNA repair genes. Remarkably, genome-wide mapping by ChIP-seq demonstrated that HOXC9 bound to 40% of these genes, including a large number of genes involved in neuronal differentiation, cell cycle progression and the DNA damage response. Moreover, we showed that HOXC9 interacted with the transcriptional repressor E2F6 and recruited it to the promoters of cell cycle genes for repressing their expression. Conclusions Our results demonstrate that HOXC9 coordinates diverse cellular processes associated with differentiation by directly activating and repressing the transcription of distinct sets of genes.
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Affiliation(s)
- Xiangwei Wang
- Cancer Center, Georgia Regents University, Augusta, GA 30912, USA.
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23
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Control of cell cycle transcription during G1 and S phases. Nat Rev Mol Cell Biol 2013; 14:518-28. [PMID: 23877564 DOI: 10.1038/nrm3629] [Citation(s) in RCA: 951] [Impact Index Per Article: 86.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The accurate transition from G1 phase of the cell cycle to S phase is crucial for the control of eukaryotic cell proliferation, and its misregulation promotes oncogenesis. During G1 phase, growth-dependent cyclin-dependent kinase (CDK) activity promotes DNA replication and initiates G1-to-S phase transition. CDK activation initiates a positive feedback loop that further increases CDK activity, and this commits the cell to division by inducing genome-wide transcriptional changes. G1-S transcripts encode proteins that regulate downstream cell cycle events. Recent work is beginning to reveal the complex molecular mechanisms that control the temporal order of transcriptional activation and inactivation, determine distinct functional subgroups of genes and link cell cycle-dependent transcription to DNA replication stress in yeast and mammals.
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Bertoli C, Klier S, McGowan C, Wittenberg C, de Bruin RAM. Chk1 inhibits E2F6 repressor function in response to replication stress to maintain cell-cycle transcription. Curr Biol 2013; 23:1629-37. [PMID: 23954429 DOI: 10.1016/j.cub.2013.06.063] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 05/28/2013] [Accepted: 06/28/2013] [Indexed: 01/18/2023]
Abstract
BACKGROUND In eukaryotic cells, detection of replication stress results in the activation of the DNA replication checkpoint, a signaling cascade whose central players are the kinases ATR and Chk1. The checkpoint response prevents the accumulation of DNA damage and ensures cell viability by delaying progression into mitosis. However, the role and mechanism of the replication checkpoint transcriptional response in human cells, which is p53 independent, is largely unknown. RESULTS We show that, in response to DNA replication stress, the regular E2F-dependent cell-cycle transcriptional program is maintained at high levels, and we establish the mechanisms governing such transcriptional upregulation. E2F6, a repressor of E2F-dependent G1/S transcription, replaces the activating E2Fs at promoters to repress transcription in cells progressing into S phase in unperturbed conditions. After replication stress, the checkpoint kinase Chk1 phosphorylates E2F6, leading to its dissociation from promoters. This promotes E2F-dependent transcription, which mediates cell survival by preventing DNA damage and cell death. CONCLUSIONS This work reveals, for the first time, that the regular cell-cycle transcriptional program is part of the DNA replication checkpoint response in human cells and establishes the molecular mechanism involved. We show that maintaining high levels of G1/S cell-cycle transcription in response to replication stress contributes to two key functions of the DNA replication checkpoint response, namely, preventing genomic instability and cell death. Given the critical role of replication stress in oncogene transformation, a detailed understanding of the molecular mechanisms involved in the checkpoint response will contribute to a better insight into cancer development.
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Affiliation(s)
- Cosetta Bertoli
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
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25
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Leseva M, Santostefano KE, Rosenbluth AL, Hamazaki T, Terada N. E2f6-mediated repression of the meiotic Stag3 and Smc1β genes during early embryonic development requires Ezh2 and not the de novo methyltransferase Dnmt3b. Epigenetics 2013; 8:873-84. [PMID: 23880518 PMCID: PMC3883790 DOI: 10.4161/epi.25522] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 06/12/2013] [Accepted: 06/24/2013] [Indexed: 12/31/2022] Open
Abstract
The E2f6 transcriptional repressor is an E2F-family member essential for the silencing of a group of meiosis-specific genes in somatic tissues. Although E2f6 has been shown to associate with both polycomb repressive complexes (PRC) and the methyltransferase Dnmt3b, the cross-talk between these repressive machineries during E2f6-mediated gene silencing has not been clearly demonstrated yet. In particular, it remains largely undetermined when and how E2f6 establishes repression of meiotic genes during embryonic development. We demonstrate here that the inactivation of a group of E2f6 targeted genes, including Stag3 and Smc1β, first occurs at the transition from mouse embryonic stem cells (ESCs) to epiblast stem cells (EpiSCs), which represent pre- and post-implantation stages, respectively. This process was accompanied by de novo methylation of their promoters. Of interest, despite a clear difference in DNA methylation status, E2f6 was similarly bound to the proximal promoter regions both in ESCs and EpiSCs. Neither E2f6 nor Dnmt3b overexpression in ESCs decreased meiotic gene expression or increased DNA methylation, indicating that additional factors are required for E2f6-mediated repression during the transition. When the SET domain of Ezh2, a core subunit of the PRC2 complex, was deleted, however, repression of Stag3 and Smc1β during embryoid body differentiation was largely impaired, indicating that the event required the enzymatic activity of Ezh2. In addition, repression of Stag3 and Smc1β occurred in the absence of Dnmt3b. The data presented here suggest a primary role of PRC2 in E2f6-mediated gene silencing of the meiotic genes.
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Affiliation(s)
- Milena Leseva
- Department of Pathology; University of Florida College of Medicine; Gainesville, FL USA
| | | | - Amy L Rosenbluth
- Department of Pathology; University of Florida College of Medicine; Gainesville, FL USA
| | - Takashi Hamazaki
- Department of Pathology; University of Florida College of Medicine; Gainesville, FL USA
- Department of Pediatrics; Osaka City University Graduate School of Medicine; Osaka, Japan
| | - Naohiro Terada
- Department of Pathology; University of Florida College of Medicine; Gainesville, FL USA
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Oberstaller J, Joseph SJ, Kissinger JC. Genome-wide upstream motif analysis of Cryptosporidium parvum genes clustered by expression profile. BMC Genomics 2013; 14:516. [PMID: 23895416 PMCID: PMC3734150 DOI: 10.1186/1471-2164-14-516] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 07/09/2013] [Indexed: 11/16/2022] Open
Abstract
Background There are very few molecular genetic tools available to study the apicomplexan parasite Cryptosporidium parvum. The organism is not amenable to continuous in vitro cultivation or transfection, and purification of intracellular developmental stages in sufficient numbers for most downstream molecular applications is difficult and expensive since animal hosts are required. As such, very little is known about gene regulation in C. parvum. Results We have clustered whole-genome gene expression profiles generated from a previous study of seven post-infection time points of 3,281 genes to identify genes that show similar expression patterns throughout the first 72 hours of in vitro epithelial cell culture. We used the algorithms MEME, AlignACE and FIRE to identify conserved, overrepresented DNA motifs in the upstream promoter region of genes with similar expression profiles. The most overrepresented motifs were E2F (5′-TGGCGCCA-3′); G-box (5′-G.GGGG-3′); a well-documented ApiAP2 binding motif (5′-TGCAT-3′), and an unknown motif (5′-[A/C] AACTA-3′). We generated a recombinant C. parvum DNA-binding protein domain from a putative ApiAP2 transcription factor [CryptoDB: cgd8_810] and determined its binding specificity using protein-binding microarrays. We demonstrate that cgd8_810 can putatively bind the overrepresented G-box motif, implicating this ApiAP2 in the regulation of many gene clusters. Conclusion Several DNA motifs were identified in the upstream sequences of gene clusters that might serve as potential cis-regulatory elements. These motifs, in concert with protein DNA binding site data, establish for the first time the beginnings of a global C. parvum gene regulatory map that will contribute to our understanding of the development of this zoonotic parasite.
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Affiliation(s)
- Jenna Oberstaller
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
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27
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Xanthoulis A, Tiniakos DG. E2F transcription factors and digestive system malignancies: How much do we know? World J Gastroenterol 2013; 19:3189-3198. [PMID: 23745020 PMCID: PMC3671070 DOI: 10.3748/wjg.v19.i21.3189] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 02/08/2013] [Accepted: 03/29/2013] [Indexed: 02/06/2023] Open
Abstract
E2F family of transcription factors regulates various cellular functions related to cell cycle and apoptosis. Its individual members have traditionally been classified into activators and repressors, based on in vitro studies. However their contribution in human cancer is more complicated and difficult to predict. We review current knowledge on the expression of E2Fs in digestive system malignancies and its clinical implications for patient prognosis and treatment. E2F1, the most extensively studied member and the only one with prognostic value, exhibits a tumor-suppressing activity in esophageal, gastric and colorectal adenocarcinoma, and in hepatocellular carcinoma (HCC), whereas in pancreatic ductal adenocarcinoma and esophageal squamous cell carcinoma may function as a tumor-promoter. In the latter malignancies, E2F1 immunohistochemical expression has been correlated with higher tumor grade and worse patient survival, whereas in esophageal, gastric and colorectal adenocarcinomas is a marker of increased patient survival. E2F2 has only been studied in colorectal cancer, where its role is not considered significant. E2F4’s role in colorectal, gastric and hepatic carcinogenesis is tumor-promoting. E2F8 is strongly upregulated in human HCC, thus possibly contributing to hepatocarcinogenesis. Adenoviral transfer of E2F as gene therapy to sensitize pancreatic cancer cells for chemotherapeutic agents has been used in experimental studies. Other therapeutic strategies are yet to be developed, but it appears that targeted approaches using E2F-agonists or antagonists should take into account the tissue-dependent function of each E2F member. Further understanding of E2Fs’ contribution in cellular functions in vivo would help clarify their role in carcinogenesis.
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28
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Biochemical and functional interactions of human papillomavirus proteins with polycomb group proteins. Viruses 2013; 5:1231-49. [PMID: 23673719 PMCID: PMC3712305 DOI: 10.3390/v5051231] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 04/23/2013] [Accepted: 04/27/2013] [Indexed: 12/22/2022] Open
Abstract
The role of enzymes involved in polycomb repression of gene transcription has been studied extensively in human cancer. Polycomb repressive complexes mediate oncogene-induced senescence, a principal innate cell-intrinsic tumor suppressor pathway that thwarts expansion of cells that have suffered oncogenic hits. Infections with human cancer viruses including human papillomaviruses (HPVs) and Epstein-Barr virus can trigger oncogene-induced senescence, and the viruses have evolved strategies to abrogate this response in order to establish an infection and reprogram their host cells to establish a long-term persistent infection. As a consequence of inhibiting polycomb repression and evading oncogene induced-senescence, HPV infected cells have an altered epigenetic program as evidenced by aberrant homeobox gene expression. Similar alterations are frequently observed in non-virus associated human cancers and may be harnessed for diagnosis and therapy.
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29
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Leung JY, Nevins JR. E2F6 associates with BRG1 in transcriptional regulation. PLoS One 2012; 7:e47967. [PMID: 23082233 PMCID: PMC3474740 DOI: 10.1371/journal.pone.0047967] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 09/19/2012] [Indexed: 11/23/2022] Open
Abstract
The E2F6 protein functions as an Rb-independent repressor of gene transcription. We have previously provided evidence suggesting a role for E2F6 in repression of E2F-responsive genes at S phase. Here, we have identified BRG1, the ATPase subunit of the SWI/SNF chromatin-remodeling complex, as an E2F6 interacting protein. Immunoprecipitation experiments demonstrate that BRG1 binds specifically to E2F6 and E2F4 but not the activator E2Fs. E2F6 was also able to interact with BAF155, a BRG1-associated factor, in the SWI/SNF complex. Chromatin immunoprecipitation assays demonstrate the binding of BRG1 coincident with E2F6 on G1/S gene promoters during S phase. Collectively, our studies suggest that E2F6 may recruit BRG1 in transcriptional regulation of genes important for G1/S phase transition of the cell cycle.
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Affiliation(s)
- Janet Y. Leung
- Duke Institute for Genome Sciences and Policy, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joseph R. Nevins
- Duke Institute for Genome Sciences and Policy, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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30
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Carvajal LA, Hamard PJ, Tonnessen C, Manfredi JJ. E2F7, a novel target, is up-regulated by p53 and mediates DNA damage-dependent transcriptional repression. Genes Dev 2012; 26:1533-45. [PMID: 22802528 DOI: 10.1101/gad.184911.111] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The p53 tumor suppressor protein is a transcription factor that exerts its effects on the cell cycle via regulation of gene expression. Although the mechanism of p53-dependent transcriptional activation has been well-studied, the molecular basis for p53-mediated repression has been elusive. The E2F family of transcription factors has been implicated in regulation of cell cycle-related genes, with E2F6, E2F7, and E2F8 playing key roles in repression. In response to cellular DNA damage, E2F7, but not E2F6 or E2F8, is up-regulated in a p53-dependent manner, with p53 being sufficient to increase expression of E2F7. Indeed, p53 occupies the promoter of the E2F7 gene after genotoxic stress, consistent with E2F7 being a novel p53 target. Ablation of E2F7 expression abrogates p53-dependent repression of a subset of its targets, including E2F1 and DHFR, in response to DNA damage. Furthermore, E2F7 occupancy of the E2F1 and DHFR promoters is detected, and expression of E2F7 is sufficient to inhibit cell proliferation. Taken together, these results show that p53-dependent transcriptional up-regulation of its target, E2F7, leads to repression of relevant gene expression. In turn, this E2F7-dependent mechanism contributes to p53-dependent cell cycle arrest in response to DNA damage.
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Affiliation(s)
- Luis A Carvajal
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA
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31
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Westendorp B, Major JL, Nader M, Salih M, Leenen FHH, Tuana BS. The E2F6 repressor activates gene expression in myocardium resulting in dilated cardiomyopathy. FASEB J 2012; 26:2569-79. [PMID: 22403008 DOI: 10.1096/fj.11-203174] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The E2F/Rb pathway regulates cardiac growth and development and holds great potential as a therapeutic target. The E2F6 repressor is a unique E2F member that acts independently of pocket proteins. Forced expression of E2F6 in mouse myocardium induced heart failure and mortality, with severity of symptoms correlating to E2F6 levels. Echocardiography demonstrated a 37% increase (P<0.05) in left ventricular end-diastolic diameter and reduced ejection fraction (<40%, P<0.05) in young transgenic (Tg) mice. Microarray and qPCR analysis revealed a paradoxical increase in E2F-responsive genes, which regulate the cell cycle, without changes in cardiomyocyte cell number or size in Tg mice. Young adult Tg mice displayed a 75% (P<0.01) decrease in gap junction protein connexin-43, resulting in abnormal electrocardiogram including a 24% (P<0.05) increase in PR interval. Further, mir-206, which targets connexin-43, was up-regulated 10-fold (P<0.05) in Tg myocardium. The mitogen-activated protein kinase pathway, which regulates the levels of miR-206 and connexin-43, was activated in Tg hearts. Thus, deregulated E2F6 levels evoked abnormal gene expression at transcriptional and post-transcriptional levels, leading to cardiac remodeling and dilated cardiomyopathy. The data highlight an unprecedented role for the strict regulation of the E2F pathway in normal postnatal cardiac function.
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Affiliation(s)
- Bart Westendorp
- Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Rd., Ottawa, ON K1H 8M5, Canada
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32
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Kim KC, Lee C. Curcumin Induces Downregulation of E2F4 Expression and Apoptotic Cell Death in HCT116 Human Colon Cancer Cells; Involvement of Reactive Oxygen Species. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2010; 14:391-7. [PMID: 21311680 DOI: 10.4196/kjpp.2010.14.6.391] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 11/29/2010] [Accepted: 12/10/2010] [Indexed: 01/30/2023]
Abstract
E2F transcription factors and their target genes have been known to play an important role in cell growth control. We found that curcumin, a polyphenolic phytochemical isolated from the plant Curcuma longa, markedly suppressed E2F4 expression in HCT116 colon cancer cells. Hydrogen peroxide was also found to decrease E2F4 protein level, indicating the involvement of reactive oxygen species (ROS) in curucmin-induced downregulation of E2F4 expression. Involvement of ROS in E2F4 downregulation in response to curcumin was confirmed by the result that pretreatment of cells with N-acetylcystein (NAC) before exposure of curcumin almost completely blocked the reduction of E2F4 expression at the protein as well as mRNA level. Anti-proliferative effect of curcumin was also suppressed by NAC which is consistent to previous reports showing curcumin-superoxide production and induction of poly (ADP-ribose) polymerase (PARP) cleavage as well as apoptosis. Expression of several genes, cyclin A, p21, and p27, which has been shown to be regulated in E2F4-dependent manner and involved in the cell cycle progression was also affected by curcumin. Moreover, decreased (cyclin A) and increased (p21 and p27) expression of these E2F4 downstream genes by curcumin was restored by pretreatment of cells with NAC and E2F4 overexpression which is induced by doxycycline. In addition, E2F4 overexpression was observed to partially ameliorate curcumin-induced growth inhibition by cell viability assay. Taken together, we found curcumin-induced ROS down-regulation of E2F4 expression and modulation of E2F4 target genes which finally lead to the apoptotic cell death in HCT116 colon cancer cells, suggesting that E2F4 appears to be a novel determinant of curcumin-induced cytotoxicity.
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Affiliation(s)
- Kyung-Chan Kim
- Department of Internal Medicine, College of Medicine, Catholic University of Daegu, Daegu 705-718, Korea
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33
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Kumar R, De Massy B. Initiation of meiotic recombination in mammals. Genes (Basel) 2010; 1:521-49. [PMID: 24710101 PMCID: PMC3966222 DOI: 10.3390/genes1030521] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 11/22/2010] [Accepted: 12/03/2010] [Indexed: 12/18/2022] Open
Abstract
Meiotic recombination is initiated by the induction of programmed DNA double strand breaks (DSBs). DSB repair promotes homologous interactions and pairing and leads to the formation of crossovers (COs), which are required for the proper reductional segregation at the first meiotic division. In mammals, several hundred DSBs are generated at the beginning of meiotic prophase by the catalytic activity of SPO11. Currently it is not well understood how the frequency and timing of DSB formation and their localization are regulated. Several approaches in humans and mice have provided an extensive description of the localization of initiation events based on CO mapping, leading to the identification and characterization of preferred sites (hotspots) of initiation. This review presents the current knowledge about the proteins known to be involved in this process, the sites where initiation takes place, and the factors that control hotspot localization.
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Affiliation(s)
- Rajeev Kumar
- Institute of Human Genetics, UPR1142, CNRS, 141 rue de la Cardonille, 34396 Montpellier cedex 5, France.
| | - Bernard De Massy
- Institute of Human Genetics, UPR1142, CNRS, 141 rue de la Cardonille, 34396 Montpellier cedex 5, France.
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34
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Conklin JF, Sage J. Keeping an eye on retinoblastoma control of human embryonic stem cells. J Cell Biochem 2010; 108:1023-30. [PMID: 19760644 DOI: 10.1002/jcb.22342] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Human embryonic stem cells (hESCs) hold great promise in regenerative medicine. However, before the full potential of these cells is achieved, major basic biological questions need to be addressed. In particular, there are still gaps in our knowledge of the molecular mechanisms underlying the derivation of hESCs from blastocysts, the regulation of the undifferentiated, pluripotent state, and the control of differentiation into specific lineages. Furthermore, we still do not fully understand the tumorigenic potential of hESCs, limiting their use in regenerative medicine. The RB pathway is a key signaling module that controls cellular proliferation, cell survival, chromatin structure, and cellular differentiation in mammalian cells. Members of the RB pathway are important regulators of hESC biology and manipulation of the activity of this pathway may provide novel means to control the fate of hESCs. Here we review what is known about the expression and function of members of the RB pathway in hESCs and discuss areas of interest in this field.
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Affiliation(s)
- Jamie F Conklin
- Department of Pediatrics, Stanford Medical School, Stanford, California 94305, USA
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35
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Hale KJ, Manaviazar S, George J. Total synthesis of (+)-A83586C, (+)-kettapeptin and (+)-azinothricin: powerful new inhibitors of beta-catenin/TCF4- and E2F-mediated gene transcription. Chem Commun (Camb) 2010; 46:4021-42. [PMID: 20405066 DOI: 10.1039/c000603c] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Herein we describe our asymmetric total syntheses of (+)-A83586C, (+)-kettapeptin and (+)-azinothricin. We also demonstrate that molecules of this class powerfully inhibit beta-catenin/TCF4- and E2F-mediated gene transcription within malignant human colon cancer cells at low drug concentrations.
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Affiliation(s)
- Karl J Hale
- The School of Chemistry and Chemical Engineering, and the Centre for Cancer Research and Cell Biology (CCRCB), Queen 's University Belfast, Stranmillis Road, Belfast, Northern Ireland, UK BT9 5AG.
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36
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Movassagh M, Bicknell KA, Brooks G. Characterisation and regulation of E2F-6 and E2F-6b in the rat heart: a potential target for myocardial regeneration? J Pharm Pharmacol 2010; 58:73-82. [PMID: 16393466 DOI: 10.1211/jpp.58.1.0009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
The E2F transcription factors are instrumental in regulating cell cycle progression and growth, including that in cardiomyocytes, which exit the cell cycle shortly after birth. E2F-6 has been demonstrated to act as a transcriptional repressor; however, its potential role in normal cardiomyocyte proliferation and hypertrophy has not previously been investigated. Here we report the isolation and characterisation of E2F-6 and E2F-6b in rat cardiomyocytes and consider its potential as a target for myocardial regeneration following injury. At the mRNA level, both rat E2F-6 and the alternatively spliced variant, E2F-6b, were expressed in E18 myocytes and levels were maintained throughout development into adulthood. Interestingly, E2F-6 protein expression was down-regulated during myocyte development suggesting that it is regulated post-transcriptionally in these cells. During myocyte hypertrophy, the mRNA expressions of E2F-6 and E2F-6b were not regulated whereas E2F-6 protein was up-regulated significantly. Indeed, E2F-6 protein expression levels closely parallel the developmental withdrawal of myocytes from the cell cycle and the subsequent reactivation of their cell cycle machinery during hypertrophic growth. Furthermore, depletion of E2F-6, using anti-sense technology, results in death of cultured neonatal myocytes. Taken together, abrogation of E2F-6 expression in neonatal cardiomyocytes leads to a significant decrease in their viability, consistent with the notion that E2F-6 might be required for maintaining normal myocyte growth.
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Affiliation(s)
- Mehregan Movassagh
- Department of Oncology, Hutchison/MRC Research Centre, University of Cambridge, Addenbrookes Hospital, Cambridgeshire, CB2 2XZ, UK
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37
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Abstract
Mutations of the retinoblastoma tumour suppressor gene (RB1) or components regulating the RB pathway have been identified in almost every human malignancy. The E2F transcription factors function in cell cycle control and are intimately regulated by RB. Studies of model organisms have revealed conserved functions for E2Fs during development, suggesting that the cancer-related proliferative roles of E2F family members represent a recent evolutionary adaptation. However, given that some human tumours have concurrent RB1 inactivation and E2F amplification and overexpression, we propose that there are alternative tumour-promoting activities for the E2F family, which are independent of cell cycle regulation.
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Affiliation(s)
- Hui-Zi Chen
- Human Cancer Genetics Program, Department of Molecular Virology, Immunology and Medical Genetics and Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA
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38
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Deng T, Kuang Y, Wang L, Li J, Wang Z, Fei J. An essential role for DNA methyltransferase 3a in melanoma tumorigenesis. Biochem Biophys Res Commun 2009; 387:611-6. [PMID: 19632198 DOI: 10.1016/j.bbrc.2009.07.093] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 07/19/2009] [Indexed: 11/17/2022]
Abstract
Abnormal DNA methylation and associated silencing of tumor suppressor genes are common to many types of cancers. Among the three coordinate DNA methyltransferases (Dnmts), Dnmt1 and Dnmt3b were both shown to be important for cancer cell survival and tumorigenesis. However, the relationship between Dnmt3a and tumorigenesis is still largely unknown. Here, we show that inhibition of Dnmt3a expression, by stable transfection of a Dnmt3a-RNA interference (RNAi) construct dramatically inhibited melanoma growth and metastasis in mouse melanoma models. Microarray analysis revealed that genes critical for the tumor immune response, were implicated in the inhibition of melanoma growth. Expression of a cluster of class I and class II MHC genes, class II transactivator (Ciita), as well as a subset of 5 chemokines (Cxcl9, Cxcl16, Ccl12, Ccl4, and Ccl2) were up-regulated. Furthermore, we determined that the promoter IV of Ciita was significantly demethylated in Dnmt3a-depleted tumors. In addition, several known tumor-related genes, which are critical for developmental processes and cell cycle, were confirmed to be misregulated, including TgfB1, Socs1, Socs2, E2F6, Ccne1, and Cyr61. The results presented in this report strongly suggest that Dnmt3a plays an essential role in melanoma tumorigenesis, and that the underlying mechanisms include the modulation of the tumor immune response, as well as other processes.
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Affiliation(s)
- Tao Deng
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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39
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Umemura S, Shirane M, Takekoshi S, Kusakabe T, Itoh J, Egashira N, Tokuda Y, Mori K, Osamura YR. Overexpression of E2F-5 correlates with a pathological basal phenotype and a worse clinical outcome. Br J Cancer 2009; 100:764-71. [PMID: 19259095 PMCID: PMC2653774 DOI: 10.1038/sj.bjc.6604900] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The purpose of the present study is to identify genes that contribute to cell proliferation or differentiation of breast cancers independent of signalling through the oestrogen receptor (ER) or human epidermal growth factor receptor 2 (HER2). An oligonucleotide microarray assayed 40 tumour samples from ER(+)/HER2(−), ER(+)/HER2(+), ER(−)/HER2(+), and ER(−)/HER2(−) breast cancer tissues. Quantitative reverse transcriptase PCR detected overexpression of a cell cycle-related transcription factor, E2F-5, in ER-negative breast cancers, and fluorescence in situ hybridisation detected gene amplification of E2F-5 in 5 out of 57 (8.8%) breast cancer samples. No point mutations were found in the DNA-binding or DNA-dimerisation domain of E2F-5. Immunohistochemically, E2F-5-positive cancers correlated with a higher Ki-67 labelling index (59.5%, P=0.001) and higher histological grades (P=0.049). E2F-5-positive cancers were found more frequently in ER(−)/progesterone receptor (PgR)(−)/HER2(−) cancer samples (51.9%, P=0.0049) and in breast cancer samples exhibiting a basal phenotype (56.0%, P=0.0012). Disease-free survival in node-negative patients with E2F-5-positive cancers was shorter than for patients with E2F-5-negative cancers. In conclusion, we identify, for the first time, a population of breast cancer cells that overexpress the cell cycle-related transcription factor, E2F-5. This E2F-5-positive breast cancer subtype was associated with an ER(−)/PgR(−)/HER2(−) status, a basal phenotype, and a worse clinical outcome.
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Affiliation(s)
- S Umemura
- Department of Pathology, Tokai University School of Medicine, Isehara, Japan.
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40
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Multiple recurrent genetic events converge on control of histone lysine methylation in medulloblastoma. Nat Genet 2009; 41:465-72. [PMID: 19270706 DOI: 10.1038/ng.336] [Citation(s) in RCA: 315] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 01/15/2009] [Indexed: 01/20/2023]
Abstract
We used high-resolution SNP genotyping to identify regions of genomic gain and loss in the genomes of 212 medulloblastomas, malignant pediatric brain tumors. We found focal amplifications of 15 known oncogenes and focal deletions of 20 known tumor suppressor genes (TSG), most not previously implicated in medulloblastoma. Notably, we identified previously unknown amplifications and homozygous deletions, including recurrent, mutually exclusive, highly focal genetic events in genes targeting histone lysine methylation, particularly that of histone 3, lysine 9 (H3K9). Post-translational modification of histone proteins is critical for regulation of gene expression, can participate in determination of stem cell fates and has been implicated in carcinogenesis. Consistent with our genetic data, restoration of expression of genes controlling H3K9 methylation greatly diminishes proliferation of medulloblastoma in vitro. Copy number aberrations of genes with critical roles in writing, reading, removing and blocking the state of histone lysine methylation, particularly at H3K9, suggest that defective control of the histone code contributes to the pathogenesis of medulloblastoma.
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41
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Lammens T, Li J, Leone G, De Veylder L. Atypical E2Fs: new players in the E2F transcription factor family. Trends Cell Biol 2009; 19:111-8. [PMID: 19201609 DOI: 10.1016/j.tcb.2009.01.002] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 12/15/2008] [Accepted: 01/06/2009] [Indexed: 10/21/2022]
Abstract
As major regulators of the cell cycle, apoptosis and differentiation, E2F transcription factors have been studied extensively in a broad range of organisms. The recent identification of atypical E2F family members further expands our structural, functional and molecular view of the cellular E2F activity. Unlike other family members, atypical E2Fs have a duplicated DNA-binding domain and control gene expression without heterodimerization with dimerization partner proteins. Recently, knockout strategies in plants and mammals have pinpointed that atypical E2Fs have a crucial role in plant cell size control, endocycle regulation, proliferation and apoptotic response upon DNA stress. Their position at the crossroads of proliferation and DNA stress response marks these novel E2F proteins as interesting study objects in the field of tumor biology.
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Affiliation(s)
- Tim Lammens
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052 Gent, Belgium
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42
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Courel M, Friesenhahn L, Lees JA. E2f6 and Bmi1 cooperate in axial skeletal development. Dev Dyn 2008; 237:1232-42. [PMID: 18366140 DOI: 10.1002/dvdy.21516] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Bmi1 is a Polycomb Group protein that functions as a component of Polycomb Repressive Complex 1 (PRC1) to control axial skeleton development through Hox gene repression. Bmi1 also represses transcription of the Ink4a-Arf locus and is consequently required to maintain the proliferative and self-renewal properties of hematopoietic and neural stem cells. Previously, one E2F family member, E2F6, has been shown to interact with Bmi1 and other known PRC1 components. However, the biological relevance of this interaction is unknown. In this study, we use mouse models to investigate the interplay between E2F6 and Bmi1. This analysis shows that E2f6 and Bmi1 cooperate in the regulation of Hox genes, and consequently axial skeleton development, but not in the repression of the Ink4a-Arf locus. These findings underscore the significance of the E2F6-Bmi1 interaction in vivo and suggest that the Hox and Ink4a-Arf loci are regulated by somewhat different mechanisms.
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Affiliation(s)
- Maria Courel
- Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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43
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Kehoe SM, Oka M, Hankowski KE, Reichert N, Garcia S, McCarrey JR, Gaubatz S, Terada N. A conserved E2F6-binding element in murine meiosis-specific gene promoters. Biol Reprod 2008; 79:921-30. [PMID: 18667754 DOI: 10.1095/biolreprod.108.067645] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
During gametogenesis, germ cells must undergo meiosis in order to become viable haploid gametes. Successful completion of this process is dependent upon the expression of genes whose protein products function specifically in meiosis. Failure to express these genes in meiotic cells often results in infertility, whereas aberrant expression in somatic cells may lead to mitotic catastrophe. The mechanisms responsible for regulating the timely expression of meiosis-specific genes have not been fully elucidated. Here we demonstrate that E2F6, a member of the E2F family of transcription factors, is essential for the repression of the newly identified meiosis-specific gene, Slc25a31 (also known as Ant4, Aac4), in somatic cells. This discovery, along with previous studies, prompted us to investigate the role of E2F6 in the regulation of meiosis-specific genes in general. Interestingly, the core E2F6-binding element (TCCCGC) was highly conserved in the proximal promoter regions of 19 out of 24 (79.2%) meiosis-specific genes. This was significantly higher than the frequency found in the promoters of all mouse genes (15.4%). In the absence of E2F6, only a portion of these meiosis-specific genes was derepressed in somatic cells. However, endogenous E2F6 bound to the promoters of these meiosis-specific genes regardless of whether they required E2F6 for their repression in somatic cells. Further, E2F6 overexpression was capable of reducing their transcription. These findings indicate that E2F6 possesses a broad ability to bind to and regulate the meiosis-specific gene population.
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Affiliation(s)
- Sarah M Kehoe
- Department of Pathology, University of Florida College of Medicine, Gainesville, Florida 32610, USA
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44
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Abstract
The papillomavirus life cycle is intimately coupled to the differentiation state of the infected epithelium. Since papillomaviruses lack most of the rate-limiting enzymes required for genome synthesis, they need to uncouple keratinocyte differentiation from cell cycle arrest and maintain or reestablish a replication-competent state within terminally differentiated keratinocytes. The human papillomavirus (HPV) E7 protein appears to be a major determinant for this activity and induces aberrant S-phase entry through the inactivation of the retinoblastoma tumor suppressor and related pocket proteins. In addition, E7 can abrogate p21 and p27. Together, this leads to the activation of E2F1 to E2F5, enhanced expression of E2F-responsive genes, and increased cdk2 activity. E2F6 is a pRB-independent, noncanonical member of the E2F transcription factor family that acts as a transcriptional repressor. E2F6 expression is activated in S phase through an E2F-dependent mechanism and thus may provide a negative-feedback mechanism that slows down S-phase progression and/or exit in response to the activation of the other E2F transcription factors. Here, we show that low- and high-risk HPV E7 proteins, as well as simian virus 40 T antigen and adenovirus E1A, can associate with and inactivate the transcriptional repression activity of E2F6, thereby subverting a critical cellular defense mechanism. This may result in the extended S-phase competence of HPV-infected cells. E2F6 is a component of polycomb group complexes, which bind to silenced chromatin and are critical for the maintenance of cell fate. We show that E7-expressing cells show decreased staining for E2F6/polycomb complexes and that this is at least in part dependent on the association with E2F6.
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45
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Yang WW, Shu B, Zhu Y, Yang HT. E2F6 inhibits cobalt chloride-mimetic hypoxia-induced apoptosis through E2F1. Mol Biol Cell 2008; 19:3691-700. [PMID: 18562691 DOI: 10.1091/mbc.e08-02-0171] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
E2F6, a potent transcriptional repressor, plays important roles in cell cycle regulation. However, roles of E2F6 in hypoxia-induced apoptosis are unknown. Here, we demonstrated biological functions of E2F6 in hypoxia-induced apoptosis and regulatory pathways. During hypoxia (CoCl(2), 800 microM)-induced human embryonic kidney 293 cell apoptosis, E2F6 expression was down-regulated with concurrent increases in E2F1 expression and transactivation. E2F6 overexpression abrogated hypoxia-induced apoptosis and alteration of E2F1. Conversely, specific knockdown of E2F6 by small interfering RNA had opposite effects. Chromatin immunoprecipitation assay confirmed that E2F6 regulated E2F1 expression through the transrepression of E2F1 promoter. Interestingly, E2F1 transactivation and apoptosis induced by hypoxia in cells stably expressing E2F1 were inhibited by E2F6 overexpression, suggesting that the inhibitory effects of E2F6 are not only mediated by the repression of E2F1 promoter. This was confirmed by E2F6-inhibited transactivation of E2F1 and apoptosis via competing with E2F1 for DNA binding sites evidenced by the different behaviors of E2F6DeltaC (C-terminal deletion) and E2F6.E68 (mutant DNA binding site) and by the lack of association of E2f6 with E2F1 protein. Moreover, hypoxia up-regulated expression of E2F1-responsive proapoptotic gene apoptosis protease-activating factor 1 was repressed by E2F6 overexpression. Together, these findings demonstrate a novel role of E2F6 in control of hypoxia-induced apoptosis through regulation of E2F1.
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Affiliation(s)
- Wei-Wei Yang
- Laboratory of Molecular Cardiology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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Enos ME, Bancos SA, Bushnell T, Crispe IN. E2F4 modulates differentiation and gene expression in hematopoietic progenitor cells during commitment to the lymphoid lineage. THE JOURNAL OF IMMUNOLOGY 2008; 180:3699-707. [PMID: 18322175 DOI: 10.4049/jimmunol.180.6.3699] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The E2F4 protein is involved in gene repression and cell cycle exit, and also has poorly understood effects in differentiation. We analyzed the impact of E2F4 deficiency on early steps in mouse hematopoietic development, and found defects in early hematopoietic progenitor cells that were propagated through common lymphoid precursors to the B and T lineages. In contrast, the defects in erythromyeloid precursor cells were self-correcting over time. This suggests that E2F4 is important in early stages of commitment to the lymphoid lineage. The E2F4-deficient progenitor cells showed reduced expression of several key lymphoid-lineage genes, and overexpression of two erythromyeloid lineage genes. However, we did not detect effects on cell proliferation. These findings emphasize the significance of E2F4 in controlling gene expression and cell fate.
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Affiliation(s)
- Megan E Enos
- Department of Microbiology and Immunology, David H Smith Center for Vaccine Biology and Immunology, University of Rochester, Rochester, NY 14620, USA
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Freeman SN, Ma Y, Cress WD. RhoBTB2 (DBC2) is a mitotic E2F1 target gene with a novel role in apoptosis. J Biol Chem 2007; 283:2353-62. [PMID: 18039672 DOI: 10.1074/jbc.m705986200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified the RhoBTB2 putative tumor suppressor gene as a direct target of the E2F1 transcription factor. Overexpression of E2F1 led to up-regulation of RhoBTB2 at the level of mRNA and protein. This also occurred during the induction of E2F1 activity in the presence of cycloheximide, thus indicating that RhoBTB2 is a direct target. RNAi-mediated knockdown of E2F1 resulted in decreased RhoBTB2 protein expression, demonstrating that RhoBTB2 is a physiological target of E2F1. Because E2F1 primarily serves to transcribe genes involved in cell cycle progression and apoptosis, we explored whether RhoBTB2 played roles in either of these processes. We found RhoBTB2 expression highly up-regulated during mitosis, which was partially dependent on the presence of E2F1. Furthermore, overexpression of RhoBTB2 induced a short term increase in cell cycle progression and proliferation, while long term expression had a negative effect on these processes. We similarly found RhoBTB2 up-regulated during drug-induced apoptosis, with this being primarily dependent on E2F1. Finally, we observed that knockdown of RhoBTB2 levels via siRNA delayed the onset of drug-induced apoptosis. Collectively, we describe RhoBTB2 as a novel direct target of E2F1 with roles in cell cycle and apoptosis.
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Affiliation(s)
- Scott N Freeman
- Molecular Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA
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48
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Bourdeau V, Deschênes J, Laperrière D, Aid M, White JH, Mader S. Mechanisms of primary and secondary estrogen target gene regulation in breast cancer cells. Nucleic Acids Res 2007; 36:76-93. [PMID: 17986456 PMCID: PMC2248750 DOI: 10.1093/nar/gkm945] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Estrogen receptors (ERs), which mediate the proliferative action of estrogens in breast cancer cells, are ligand-dependent transcription factors that regulate expression of their primary target genes through several mechanisms. In addition to direct binding to cognate DNA sequences, ERs can be recruited to DNA through other transcription factors (tethering), or affect gene transcription through modulation of signaling cascades by non-genomic mechanisms of action. To better characterize the mechanisms of gene regulation by estrogens, we have identified more than 700 putative primary and about 1300 putative secondary target genes of estradiol in MCF-7 cells through microarray analysis performed in the presence or absence of the translation inhibitor cycloheximide. Although siRNA-mediated inhibition of ERalpha expression antagonized the effects of estradiol on up- and down-regulated primary target genes, estrogen response elements (EREs) were enriched only in the vicinity of up-regulated genes. Binding sites for several other transcription factors, including proteins known to tether ERalpha, were enriched in up- and/or down-regulated primary targets. Secondary estrogen targets were particularly enriched in sites for E2F family members, several of which were transcriptionally regulated by estradiol, consistent with a major role of these factors in mediating the effects of estrogens on gene expression and cellular growth.
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Affiliation(s)
- Véronique Bourdeau
- Institute for Research in Immunology and Cancer and Biochemistry Department, Université de Montréal, C.P. 6128 Succursale Centre Ville, Montréal, QC H3C 3J7, Canada
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Garneau H, Alvarez L, Paquin MC, Lussier C, Rancourt C, Tremblay E, Beaulieu JF, Rivard N. Nuclear expression of E2F4 induces cell death via multiple pathways in normal human intestinal epithelial crypt cells but not in colon cancer cells. Am J Physiol Gastrointest Liver Physiol 2007; 293:G758-72. [PMID: 17656449 DOI: 10.1152/ajpgi.00050.2007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
E2F transcription factors control cell cycle progression. The localization of E2F4 in intestinal epithelial cells is cell cycle dependent, being cytoplasmic in quiescent differentiated cells but nuclear in proliferative cells. However, whether nuclear translocation of E2F4 alone is sufficient to trigger intestinal epithelial cell proliferation remains to be established. Adenoviruses expressing fusion proteins between green fluorescent protein (GFP) and wild-type (wt)E2F4 or GFP and nuclear localization signal (NLS)-tagged E2F4 were used to infect normal human intestinal epithelial crypt cells (HIEC). In contrast to expression of wtE2F4, persistent expression of E2F4 into the nucleus of HIEC triggered phosphatidylserine exposure, cytoplasmic shrinkage, zeiosis, formation of apoptotic bodies, and activation of caspase 9 and caspase 3. Inhibition of caspase activities by zVAD-fmk partially inhibited cell death induced by E2F4-NLS. An induction of p53, phosphorylated Ser15-p53, PUMA, FAS, BAX, RIP, and phosphorylated JNK1 was also observed in HIEC expressing E2F4-NLS compared with wtE2F4-expressing cells. E2F1 and p14ARF expression remained unaltered. Downregulation of p53 expression by RNA interference attenuated cell death induced by E2F4-NLS. By contrast, the level of cell death was negligible in colon cancer cells despite the strong expression of E2F4 into the nucleus. In conclusion, deregulated nuclear E2F4 expression induces apoptosis via multiple pathways in normal intestinal epithelial cells but not in colon cancer cells. Hence, mutations that deregulate E2F4 localization may provide an initial proliferative advantage but at the same time accelerate cell death. However, intestinal cells acquiring mutations (e.g., p53, Bax loci, etc.) may escape apoptosis, thereby revealing the full mitogenic potential of the E2F4 transcription factor.
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Affiliation(s)
- Hugo Garneau
- Département d'Anatomie et de Biologie Cellulaire, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, J1H5N4, Canada
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50
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Xu X, Bieda M, Jin VX, Rabinovich A, Oberley MJ, Green R, Farnham PJ. A comprehensive ChIP-chip analysis of E2F1, E2F4, and E2F6 in normal and tumor cells reveals interchangeable roles of E2F family members. Genome Res 2007; 17:1550-61. [PMID: 17908821 PMCID: PMC2045138 DOI: 10.1101/gr.6783507] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Using ChIP-chip assays (employing ENCODE arrays and core promoter arrays), we examined the binding patterns of three members of the E2F family in five cell types. We determined that most E2F1, E2F4, and E2F6 binding sites are located within 2 kb of a transcription start site, in both normal and tumor cells. In fact, the majority of promoters that are active (as defined by TAF1 or POLR2A binding) in GM06990 B lymphocytes and Ntera2 carcinoma cells were also bound by an E2F. This very close relationship between E2F binding sites and binding sites for general transcription factors in both normal and tumor cells suggests that a chromatin-bound E2F may be a signpost for active transcription initiation complexes. In general, we found that several E2Fs bind to a given promoter and that there is only modest cell type specificity of the E2F family. Thus, it is difficult to assess the role of any particular E2F in transcriptional regulation, due to extreme redundancy of target promoters. However, Ntera2 carcinoma cells were exceptional in that a large set of promoters were bound by E2F6, but not by E2F1 or E2F4. It has been proposed that E2F6 contributes to gene silencing by recruiting enzymes involved in methylating histone H3. To test this hypothesis, we created Ntera2 cell lines harboring shRNAs to E2F6. We found that reduction of E2F6 only induced minimal alteration of the transcriptome of Ntera2 transcriptome. Our results support the concept of functional redundancy in the E2F family and suggest that E2F6 is not critical for histone methylation.
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Affiliation(s)
- Xiaoqin Xu
- Department of Pharmacology and the Genome Center, University of California-Davis, Davis, California 95616, USA
| | - Mark Bieda
- Department of Pharmacology and the Genome Center, University of California-Davis, Davis, California 95616, USA
| | - Victor X. Jin
- Department of Pharmacology and the Genome Center, University of California-Davis, Davis, California 95616, USA
| | - Alina Rabinovich
- Department of Pharmacology and the Genome Center, University of California-Davis, Davis, California 95616, USA
| | - Mathew J. Oberley
- University of Wisconsin Medical School, Madison, Wisconsin, 53705 USA
| | - Roland Green
- NimbleGen Systems Inc., Madison, Wisconsin, 53711 USA
| | - Peggy J. Farnham
- Department of Pharmacology and the Genome Center, University of California-Davis, Davis, California 95616, USA
- Corresponding author.E-mail ; fax (530) 754-9658
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