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Anand S, Khan MA, Zubair H, Sudan SK, Vikramdeo KS, Deshmukh SK, Azim S, Srivastava SK, Singh S, Singh AP. MYB sustains hypoxic survival of pancreatic cancer cells by facilitating metabolic reprogramming. EMBO Rep 2023; 24:e55643. [PMID: 36592158 PMCID: PMC9986821 DOI: 10.15252/embr.202255643] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 12/13/2022] [Accepted: 12/19/2022] [Indexed: 01/03/2023] Open
Abstract
Extensive desmoplasia and poor vasculature renders pancreatic tumors severely hypoxic, contributing to their aggressiveness and therapy resistance. Here, we identify the HuR/MYB/HIF1α axis as a critical regulator of the metabolic plasticity and hypoxic survival of pancreatic cancer cells. HuR undergoes nuclear-to-cytoplasmic translocation under hypoxia and stabilizes MYB transcripts, while MYB transcriptionally upregulates HIF1α. Upon MYB silencing, pancreatic cancer cells fail to survive and adapt metabolically under hypoxia, despite forced overexpression of HIF1α. MYB induces the transcription of several HIF1α-regulated glycolytic genes by directly binding to their promoters, thus enhancing the recruitment of HIF1α to hypoxia-responsive elements through its interaction with p300-dependent histone acetylation. MYB-depleted pancreatic cancer cells exhibit a dramatic reduction in tumorigenic ability, glucose-uptake and metabolism in orthotopic mouse model, even after HIF1α restoration. Together, our findings reveal an essential role of MYB in metabolic reprogramming that supports pancreatic cancer cell survival under hypoxia.
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Affiliation(s)
- Shashi Anand
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Mohammad Aslam Khan
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Haseeb Zubair
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Sarabjeet Kour Sudan
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Kunwar Somesh Vikramdeo
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Sachin Kumar Deshmukh
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Shafquat Azim
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Sanjeev Kumar Srivastava
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Seema Singh
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL, USA
| | - Ajay Pratap Singh
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL, USA
- Cancer Biology Program, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL, USA
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Wang Z, Zhang C, Warden CD, Liu Z, Yuan YC, Guo C, Wang C, Wang J, Wu X, Ermel R, Vonderfecht SL, Wang X, Brown C, Forman S, Yang Y, James You M, Chen W. Loss of SIRT1 inhibits hematopoietic stem cell aging and age-dependent mixed phenotype acute leukemia. Commun Biol 2022; 5:396. [PMID: 35484199 PMCID: PMC9051098 DOI: 10.1038/s42003-022-03340-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 04/05/2022] [Indexed: 01/07/2023] Open
Abstract
Aging of hematopoietic stem cells (HSCs) is linked to various blood disorders and malignancies. SIRT1 has been implicated in healthy aging, but its role in HSC aging is poorly understood. Surprisingly, we found that Sirt1 knockout improved the maintenance of quiescence of aging HSCs and their functionality as well as mouse survival in serial bone marrow transplantation (BMT) recipients. The majority of secondary and tertiary BMT recipients of aging wild type donor cells developed B/myeloid mixed phenotype acute leukemia (MPAL), which was markedly inhibited by Sirt1 knockout. SIRT1 inhibition also reduced the growth and survival of human B/myeloid MPAL cells. Sirt1 knockout suppressed global gene activation in old HSCs, prominently the genes regulating protein synthesis and oxidative metabolism, which may involve multiple downstream transcriptional factors. Our results demonstrate an unexpected role of SIRT1 in promoting HSC aging and age-dependent MPAL and suggest SIRT1 may be a new therapeutic target for modulating functions of aging HSCs and treatment of MPAL.
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Affiliation(s)
- Zhiqiang Wang
- grid.410425.60000 0004 0421 8357Department of Cancer Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA ,grid.410425.60000 0004 0421 8357Department of Hematology and Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, CA 91010 USA
| | - Chunxiao Zhang
- grid.410425.60000 0004 0421 8357Department of Cancer Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA
| | - Charles David Warden
- grid.410425.60000 0004 0421 8357Integrative Genomics Core, Department of Molecular and Cellular Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA
| | - Zheng Liu
- grid.410425.60000 0004 0421 8357Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA
| | - Yate-Ching Yuan
- grid.410425.60000 0004 0421 8357Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA
| | - Chao Guo
- grid.410425.60000 0004 0421 8357Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA
| | - Charles Wang
- grid.410425.60000 0004 0421 8357Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA ,grid.43582.380000 0000 9852 649XPresent Address: Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350 USA
| | - Jinhui Wang
- grid.410425.60000 0004 0421 8357Integrative Genomics Core, Department of Molecular and Cellular Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA
| | - Xiwei Wu
- grid.410425.60000 0004 0421 8357Integrative Genomics Core, Department of Molecular and Cellular Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA
| | - Richard Ermel
- grid.410425.60000 0004 0421 8357Center for Comparative Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA
| | | | - Xiuli Wang
- grid.410425.60000 0004 0421 8357Department of Hematology and Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, CA 91010 USA
| | - Christine Brown
- grid.410425.60000 0004 0421 8357Department of Hematology and Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, CA 91010 USA
| | - Stephen Forman
- grid.410425.60000 0004 0421 8357Department of Hematology and Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, CA 91010 USA
| | - Yaling Yang
- grid.240145.60000 0001 2291 4776Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030 USA
| | - M. James You
- grid.240145.60000 0001 2291 4776Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030 USA
| | - WenYong Chen
- grid.410425.60000 0004 0421 8357Department of Cancer Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 USA
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Xie R, Yang Y, Zhang H, Liu H, Guo J, Qin H, Ma Y, Goel A, Li X, Wei Q. c-Myb and its Effector COX-2 as an Indicator Associated with Prognosis and Therapeutic Outcome in Colorectal Cancer. J Cancer 2019; 10:1601-1610. [PMID: 31205515 PMCID: PMC6548004 DOI: 10.7150/jca.27261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 01/04/2019] [Indexed: 02/06/2023] Open
Abstract
Background: One of our previous studies have demonstrated that the cancer suppressor miR-150 regulated the progression of colorectal cancer (CRC) by down-regulating v-myb avian myeloblastosis viral oncogene homolog (c-Myb). The purpose of present study was to evaluate the prognostic value of the expression of c-Myb and its effector, prostaglandin-endoperoxide synthase 2 (COX-2) in patients with CRC. Methods: We used tissue microarrays (containing 202 CRC tissues and matched adjacent normal tissues) and conducted immunohistochemical analysis and western blotting analysis (containing 3 CRC tissues and matched adjacent normal tissues) to detect the expression of c-Myb and COX-2. Results: Compared with the adjacent nontumorous tissues, both the expression levels of c-Myb and COX-2 were higher in the cancer tissues. A statistically significant correlation was found between the expression of c-Myb and COX-2. Elevated c-Myb and COX-2 were associated with more advanced tumor invasion and poorer overall survival by univariate analysis. Higher expression levels of both c-Myb and COX-2 were significantly associated with shorter overall survival for stage II and stage III patients with 5-Fu based chemotherapy. Multivariate analysis identified the lymph node involvement, distant metastatic spread and the elevated c-Myb and COX-2 as independent factors of poor prognosis for CRC. Conclusions: In conclusion, the overexpression of both c-Myb and COX-2 would be of prognostic screening value in patients with CRC.
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Affiliation(s)
- Ruting Xie
- Department of Pathology, Shanghai Tenth People's Hospital, Tongji University, Shanghai200072, P.R. China
| | - Yongzhi Yang
- Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Shanghai, 200032, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Huizhen Zhang
- Department of Pathology, Shanghai Sixth People's Hospital, Shanghai Jiaotong University, Shanghai200233, P.R. China
| | - Hu Liu
- Department of Pathology, Shanghai Tenth People's Hospital, Tongji University, Shanghai200072, P.R. China
| | - Jing Guo
- Department of Pathology, Shanghai Tenth People's Hospital, Tongji University, Shanghai200072, P.R. China
| | - Huanlong Qin
- Department of Surgery, Shanghai Tenth People's Hospital Affiliated with Tongji University, Shanghai 200072, P. R. China
| | - Yanlei Ma
- Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Shanghai, 200032, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Ajay Goel
- Center for Translational Epigenomics and Oncology, Baylor Scott & White Research Institute and Charles A Sammons Cancer Center, Baylor University Medical Center, Dallas, TX, United States
| | - Xinxiang Li
- Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Shanghai, 200032, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Qing Wei
- Department of Pathology, Shanghai Tenth People's Hospital, Tongji University, Shanghai200072, P.R. China
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Fu H, Yang P, Hai J, Li H. Utilization of circular dichroism and electrospray ionization mass spectrometry to understand the formation and conversion of G-quadruplex DNA at the human c-myb proto-oncogene. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 203:70-76. [PMID: 29860170 DOI: 10.1016/j.saa.2018.05.079] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 05/25/2018] [Accepted: 05/26/2018] [Indexed: 06/08/2023]
Abstract
G-quadruplex DNAs are involved in a number of key biological processes, including gene expression, transcription, and apoptosis. The c-myb oncogene contains a number of GGA repeats in its promoter which forms G-quadruplex, thus it could be used as a target in cancer therapeutics. Several in-vitro studies have used Circular Dichroism (CD) spectroscopy or electrospray ionization mass spectrometry (ESI-MS) to demonstrate formation and stability of G-quadruplex DNA structure in the promoter region of human c-myb oncogene. The factors affecting the c-myb G-quadruplex structures were investigated, such as cations (i.e. K+, NH4+ and Na+) and co-solutes (methanol and polyethylene glycol). The results indicated that the presence of cations and co-solutes could change the G-quadruplex structural population and promote its thermodynamic stabilization as indicated by CD melting curves. It indicated that the co-solutes preferentially stabilize the c-myb G-quadruplex structure containing both homo- and hetero-stacking. In addition, protopine was demonstrated as a binder of c-myb G-quadruplex as screened from a library of natural alkaloids using ESI-MS method. CD spectra showed that it could selectively stabilize the c-myb G-quadruplex structure compared to other six G-quadruplexes from tumor-related G-rich sequences and the duplex DNAs (both long and short-chain ones). The binding of protopine could induce the change in the G-quadruplex structural populations. Therefore, protopine with its high binding specificity could be considered as a precursor for the design of drugs to target and regulate c-myb oncogene transcription.
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Affiliation(s)
- Hengqing Fu
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China
| | - Pengfei Yang
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China
| | - Jinhui Hai
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China
| | - Huihui Li
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China.
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Zhang J, Shu Y, Qu Y, Zhang L, Chu T, Zheng Y, Zhao H. C-myb Plays an Essential Role in the Protective Function of IGF-1 on Cytotoxicity Induced by Aβ 25-35 via the PI3K/Akt Pathway. J Mol Neurosci 2017; 63:412-418. [PMID: 29110181 DOI: 10.1007/s12031-017-0991-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 10/11/2017] [Indexed: 01/23/2023]
Abstract
There have been numerous reports about neurodegenerative diseases, including Alzheimer's disease. Nevertheless, the molecules responsible for the neurodegeneration in Alzheimer's disease are basically unknown. Recent findings indicate that the cellular myeloblastosis (c-myb) regulates neural progenitor cell proliferation. In the current study, the function of insulin-like growth factor-1 (IGF-1) against cell toxicity in SH-SY5Y cells induced by β-amyloid 25-35 (Aβ25-35) and its molecular mechanism were investigated. It was found that p25 protein production was raised by Aβ25-35 (25 μM), similar to the increased expression of μ-calpain. The results also showed that Aβ25-35 reduced c-myb, elevated tau hyper-phosphorylation, and induced death of SH-SY5Y cells. Loss of cell viability and apoptosis of SH-SY5Y cells induced by Aβ25-35 were attenuated by IGF-1 pretreatment in a dose-dependent manner. In addition, IGF-1 blocked μ-calpain expression, which was induced by Aβ25-35 and reduced p25 formation and tau hyper-phosphorylation. Moreover, the expression of c-myb in SH-SY5Y cells was increased by combining IGF-1 with Aβ25-35 or IGF-1 alone. The neuroprotective function of IGF-1 was attenuated in the SH-SY5Y cells, which were transfected with a c-myb small interfering RNA. Furthermore, LY294002, a specific PI3K inhibitor, reduced c-myb expression and abolished IGF-1's protective function in SH-SY5Y cell apoptosis induced by Aβ25-35. The facts above indicate that c-myb has a role in IGF-1-mediated protection from Aβ25-35-induced cytotoxicity via the PI3K/Akt pathway.
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Affiliation(s)
- Jingyu Zhang
- Department of Neurology, Fourth Affiliated Hospital of Harbin Medical University, 37 Yiyuan Street, Nangang District, Harbin, Heilongjiang Province, 150001, China
| | - Yongwei Shu
- Department of Neurology, Fourth Affiliated Hospital of Harbin Medical University, 37 Yiyuan Street, Nangang District, Harbin, Heilongjiang Province, 150001, China
| | - Yang Qu
- Department of Neurology, Fourth Affiliated Hospital of Harbin Medical University, 37 Yiyuan Street, Nangang District, Harbin, Heilongjiang Province, 150001, China
| | - Lina Zhang
- Department of Neurology, Fourth Affiliated Hospital of Harbin Medical University, 37 Yiyuan Street, Nangang District, Harbin, Heilongjiang Province, 150001, China
| | - Tingting Chu
- Department of Neurology, Fourth Affiliated Hospital of Harbin Medical University, 37 Yiyuan Street, Nangang District, Harbin, Heilongjiang Province, 150001, China
| | - Yonghui Zheng
- Department of Neurology, Fourth Affiliated Hospital of Harbin Medical University, 37 Yiyuan Street, Nangang District, Harbin, Heilongjiang Province, 150001, China
| | - Hong Zhao
- Department of Neurology, Fourth Affiliated Hospital of Harbin Medical University, 37 Yiyuan Street, Nangang District, Harbin, Heilongjiang Province, 150001, China.
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Yu R, Li C, Lin X, Chen Q, Li J, Song L, Lin L, Liu J, Zhang Y, Kong W, Ouyang X, Chen X. Clinicopathologic features and prognostic implications of MYBL2 protein expression in pancreatic ductal adenocarcinoma. Pathol Res Pract 2017; 213:964-968. [PMID: 28559119 DOI: 10.1016/j.prp.2017.04.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/27/2017] [Accepted: 04/26/2017] [Indexed: 01/22/2023]
Abstract
MYBL2 (B-MYB), a member of the MYB family of transcription factor genes, regulates the expression of genes in the process of tumorigenesis. Many studies have shown that MYBL2 is high expresssion in several human malignancies including pancreatic ductal adenocarcinoma (PDAC). However, its role in PDAC is still unclear. The present study is designed to investigate MYBL2 expression levels and prognostic significance in PDAC patients. We assessed MYBL2 expression level by immunohistochemistry in tumor tissues from 93 PDAC patients undergoing curative resection. The association of MYBL2 expression with clinicopathological parameters was evaluated by Pearson's chi-square (χ2) test, Fisher's exact test, and Spearman's rank. Kaplan-Meier survival analysis and Cox proportional hazards models were used to estimate the effect of MYBL2 expression on survival. The expression of MYBL2 was significantly higher in PDAC cells compared with adjacent non-cancerous tissues (P=0.000). The overexpression of MYBL2 in the tumor tissues was significantly correlated with a higher T classification (p=0.002), peri-neural invasion (PNI) (p=0.013) and vital status (p=0.045). Kaplan-Meier analysis indicated that high MYBL2 expression was significantly associated with shorter overall survival times in PDAC patients. Moreover, univariate and multivariate analysis confirmed MYBL2 expression (P=0.010), histological grade (P=0.001) as independent prognostic factors in PDAC. These results suggested that overexpression of MYBL2 might serve as a novel prognostic biomarker in PDAC patients.
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Affiliation(s)
- Ranjie Yu
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China
| | - Chengyi Li
- Department of Surgical Oncology, Affiliated Mindong Hospital of Fujian Medical University, Fuan 355000, Fujian, China
| | - Xiaomei Lin
- Department of Oncology, Fujian University of Traditional Chinese Medicine Subsidiary Rehabilitation Hospital, Fuzhou 350122, Fujian, China
| | - Qun Chen
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China
| | - Jie Li
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China
| | - Li Song
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China
| | - Lin Lin
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China
| | - Jingnan Liu
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China
| | - Yan Zhang
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China
| | - Wencui Kong
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China
| | - Xuenong Ouyang
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China
| | - Xiong Chen
- Department of Oncology, Fuzhou General Hospital of Nanjing Military Command, Fuzong Clinical College of Fujian Medical University, Fuzhou 350025, Fujian, China.
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Achinko DA, Dormer A, Narayanan M, Norman EF, Abbas M. Identification of genetic pathways driving Ebola virus disease in humans and targets for therapeutic intervention. F1000Res 2016. [DOI: 10.12688/f1000research.9778.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Introduction: LCK gene, also known as lymphocyte-specific proto-oncogene, is expressed in lymphocytes, and associated with coordinated expression of MHC class I and II in response to physiological stimuli, mediated through a combined interaction of promoters, suppressors, and enhancers. Differential usage of LCK promoters, transcribes dysfunctional transcript variants leading to leukemogenesis and non-induction of MHC class I gene variants. Viruses use C-type lectins, like CD209, to penetrate the cell, and inhibit Pattern Recognition Receptors (PRR), hence evading immune destruction. Given that Ebolavirus (EBOV) disease burden could result from a dysfunctional LCK pathway, identification of the genetic pathway leading to proper immune induction is a major priority. Methods: Data for EBOV related virus samples were obtained from Gene Expression Omnibus database and RMEAN information per gene per sample were entered into a table of values. R software v.3.3.1 was used to process differential expression patterns across samples for LCK, CD209 and immune-related genes. Principal component analysis (PCA) using ggbiplot v.0.55 was used to explain the variance across samples. Results: Data analyses identified three viral clusters based on transmission patterns as follows: LCK-CD209 dependent, LCK-dependent specific to EBOV, and CD209 dependent. Compared to HLA class II gene variants, HLA class I (A, B and C) variants were <2 fold expressed, especially for EBOV samples. PCA analyses classified TYRO3, TBK1 and LCK genes independent of the data, leading to identification of a possible pathway involving LCK, IL2, PI3k, TBK1, TYRO3 and MYB genes with downstream induction of immune T-cells. Discussion: This is the first study undertaken to understand the non-functional immune pathway, leading to EBOV disease pathogenesis and high fatality rates. Our lab currently exploits, through cutting edge genetic technology to understand the interplay of identified genes required for proper immune induction. This will guide antiviral therapy and possible markers for viral disease identification during outbreaks.
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Li H, Hai J, Zhou J, Yuan G. The formation and characteristics of the i-motif structure within the promoter of the c-myb proto-oncogene. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2016; 162:625-632. [PMID: 27487467 DOI: 10.1016/j.jphotobiol.2016.07.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/21/2016] [Accepted: 07/24/2016] [Indexed: 12/11/2022]
Abstract
C-myb proto-oncogene is a potential therapeutic target for some human solid tumors and leukemias. A long cytosine-rich sequence, which locates the downstream of the transcription initiation site, is demonstrated to fold into an intramolecular i-motif DNA using electrospray ionization mass spectrometry (ESI-MS) and circular dichroism (CD) spectroscopy. Effects of factors, including the pH value, the number of C:C(+) dimers, the concentration of buffer, the molecular crowding condition, and the coexistence of the complementary DNA, on the formation and the structural stability of the i-motif DNA are systematically studied. We have demonstrated that the i-motif folding in the c-myb promoter could be accelerated upon synergistic physiological stimuli including intracellular molecular crowding and low pH values, as well as the large number of the i-motif C:C(+) dimers. Meanwhile, various inputs, such as acids/bases and metal ions, have exhibited their abilities in controlling the conformational switch of the c-myb GC-rich DNA. Acidic pH values and the presence of K(+) ions can induce the dissociation of the double helix. Our present strategy can greatly extend the potential usages of i-motif DNA molecules with specific sequences as conformational switch-controlled devices. Moreover, this work demonstrates the superiority of CD spectroscopy associated with ESI-MS as a rapid, more cost-effective and sensitive structural change responsive method in the research of DNA conformational switching.
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Affiliation(s)
- Huihui Li
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China; Department of Chemistry, University of British Columbia, Vancouver V6T 1Z1, Canada.
| | - Jinhui Hai
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China; National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China
| | - Jiang Zhou
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Gu Yuan
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
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9
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c-myb hyperactivity leads to myeloid and lymphoid malignancies in zebrafish. Leukemia 2016; 31:222-233. [PMID: 27457538 DOI: 10.1038/leu.2016.170] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 05/30/2016] [Accepted: 06/03/2016] [Indexed: 12/17/2022]
Abstract
The c-MYB transcription factor is a key regulator of hematopoietic cell proliferation and differentiation, and dysregulation of c-MYB activity often associates with various hematological disorders. Yet, its pathogenic role remains largely unknown due to lack of suitable animal models. Here, we report a detail characterization of a c-myb-gfp transgenic zebrafish harboring c-Myb hyperactivity (named c-mybhyper). This line exhibits abnormal granulocyte expansion that resembles human myelodysplastic syndrome (MDS) from embryonic stage to adulthood. Strikingly, a small portion of c-mybhyper adult fish develops acute myeloid leukemia-like or acute lymphoid leukemia-like disorders with age. The myeloid and lymphoid malignancies in c-mybhyper adult fish are likely caused by the hyperactivity of c-myb, resulting in the dysregulation of a number of cell-cycle-related genes and hyperproliferation of hematopoietic precursor cells. Finally, treatment with c-myb target drug flavopiridol can relieve the MDS-like symptoms in both c-mybhyper embryos and adult fish. Our study establishes a zebrafish model for studying the cellular and molecular mechanisms underlying c-Myb-associated leukemogenesis as well as for anti-leukemic drug screening.
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Li H, Hai J, Zhou J, Yuan G. Exploration of binding affinity and selectivity of brucine with G-quadruplex in the c-myb proto-oncogene by electrospray ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:407-414. [PMID: 26754134 DOI: 10.1002/rcm.7454] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 11/07/2015] [Accepted: 11/09/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE The c-myb gene is a potential therapeutic target for human tumors and leukemias. Active ingredients from natural products may be used as drugs in chemotherapy for human cancers. Here, electrospray ionization mass spectrometry (ESI-MS) was used to probe the formation and recognition of the G-quadruplex structure from the G-rich sequence that is found in the c-myb gene promoter, 5'-GGGCTGGGCTGGGCGGGG-3'. The aim of our study is to evaluate a potential binder for the c-myb gene from natural products, and thereby to modulate c-myb gene expression. METHODS ESI-MS, as an effective method, was utilized not only to characterize the formation of the G-quadruplex in the c-myb oncogene, but also as a tool to probe the binding characteristics of alkaloid molecules with the target G-quadruplex DNA. RESULTS ESI-MS results with the support of circular dichroism (CD) spectra demonstrated the formation of an intramolecular parallel-stranded G-quadruplex in the c-myb oncogene promoter. A screening of six alkaloid molecules showed that brucine (P1) had a strong binding affinity to the c-myb G-quadruplex DNA. It is notable that P1 can bind selectively to the c-myb G-quadruplex with respect to duplex DNAs, as well as to G-quadruplexes in other types of gene sequences. According to ESI-MS results, in which the stability was tested by capillary heating and collision-induced dissociation, the binding of P1 could thermally stabilize the c-myb G-quadruplex DNA. CONCLUSIONS In this work, brucine (P1), an alkaloid molecule, has been found to bind to the intramolecular parallel G-quadruplex in the c-myb oncogene promoter with high affinity and selectivity, and could thermally stabilize the c-myb G-quadruplex DNA, indicating that the binding of P1 has the potential to modulate c-myb gene expression. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Huihui Li
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing, 210023, China
| | - Jinhui Hai
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing, 210023, China
| | - Jiang Zhou
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Gu Yuan
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
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Dong Y, Zhao Q, Liu X, Zhang X, Qi Z, Zhang H, Zheng X, Zhang Z. MoMyb1 is required for asexual development and tissue-specific infection in the rice blast fungus Magnaporthe oryzae. BMC Microbiol 2015; 15:37. [PMID: 25885817 PMCID: PMC4336695 DOI: 10.1186/s12866-015-0375-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 02/04/2015] [Indexed: 11/28/2022] Open
Abstract
Background The Myb super-family of proteins contain a group of functionally diverse transcriptional activators found in plant, animal and fungus. Myb proteins are involved in cell proliferation, differentiation and apoptosis, and have crucial roles in telomeres. The purpose of this study was to characterize the biological function of Myb1 protein in the rice blast fungus Magnaporthe oryzae. Results We identified the Saccharomyces cerevisiae BAS1 homolog MYB1 in M. oryzae, named MoMyb1. MoMyb1 encodes a protein of 322 amino acids and has two SANT domains and is well conserved in various organisms. Targeted gene deletion of MoMYB1 resulted in a significant reduction in vegetative growth and showed defects in conidiation and conidiophore development. Quantitative RT-PCR analysis revealed that the transcription levels of several conidiophore-related genes were apparently decreased in the ΔMomyb1 mutant. Inoculation with mycelia mats displayed that the virulence of the ΔMomyb1 mutant was not changed on rice leaves but was non-pathogenic on rice roots in comparison to the wild type Guy11. In addition, ∆Momyb1 mutants showed increased resistance to osmotic stresses but more sensitive to cell wall stressor calcofluor white (CFW). Further analysis revealed that MoMyb1 has an important role in the cell wall biosynthesis pathway. Conclusion This study provides the evidence that MoMyb1 is a key regulator involved in conidiogenesis, stress response, cell wall integrity and pathogenesis on rice roots in the filamentous phytopathogen M. oryzae. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0375-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yanhan Dong
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, 210095, China.
| | - Qian Zhao
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, 210095, China.
| | - Xinyu Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, 210095, China.
| | - Xiaofang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, 210095, China.
| | - Zhongqiang Qi
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, 210095, China.
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, 210095, China.
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, 210095, China.
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, 210095, China.
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12
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Cui X, Zhang Q, Chen H, Zhou J, Yuan G. ESI mass spectrometric exploration of selective recognition of G-quadruplex in c-myb oncogene promoter using a novel flexible cyclic polyamide. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:684-691. [PMID: 24452297 DOI: 10.1007/s13361-013-0802-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/30/2013] [Accepted: 12/03/2013] [Indexed: 06/03/2023]
Abstract
In this research, electrospray ionization mass spectrometry (ESI-MS) was used to probe the binding selectivity of a flexible cyclic polyamide (cβ) to G-quadruplexes from the long G-rich sequences in the c-myb oncogene promoter. The results show that three G-rich sequences, including d[(GGA)3GGTCAC(GGA)4], d[(GGA)4GAA(GGA)4], and d[(GGA)3GGTCAC(GGA)4GAA(GGA)4] species in the c-myb promoter can form parallel G-quadruplexes, and cβ selectively binds towards these G-quadruplexes over both several other G-quadruplexes and the duplex DNA. These properties of cβ have profound implications on future studies of the regulation of c-myb oncogene expression.
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Affiliation(s)
- Xiaojie Cui
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
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13
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Mendoza PR, Jakobiec FA, Krane JF. Immunohistochemical features of lacrimal gland epithelial tumors. Am J Ophthalmol 2013; 156:1147-1158.e1. [PMID: 23972314 DOI: 10.1016/j.ajo.2013.06.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 06/23/2013] [Accepted: 06/24/2013] [Indexed: 11/19/2022]
Abstract
PURPOSE To investigate the immunohistochemical features of ocular adnexal pleomorphic adenoma and adenoid cystic carcinoma. DESIGN Retrospective clinicopathologic study. METHODS Clinical records and microscopic slides of 7 cases of each tumor type were reviewed. Immunohistochemical probes for Ki-67 and p53, and newer nuclear markers MYB for adenoid cystic carcinoma and PLAG1 for pleomorphic adenoma, were employed. RESULTS Pleomorphic adenomas were asymptomatic, whereas adenoid cystic carcinomas were painful. No pleomorphic adenomas recurred; 4 adenoid cystic carcinomas recurred, resulting in 3 deaths. Unusual histopathologic variants for which immunohistochemistry proved useful included a myoepithelioma, an atypical pleomorphic adenoma, tubular and solid/basaloid variants of adenoid cystic carcinoma, and a morphologically heterogeneous adenoid cystic carcinoma of a Wolfring gland. For the pleomorphic adenomas, the average Ki-67 proliferation index was 3.8%; p53 was weakly staining, with an average positivity of 18.5%; PLAG1 was strongly positive in all cases; MYB was negative in 5 cases and weakly focally positive in 2 cases. For the adenoid cystic carcinomas, the average Ki-67 proliferation index was 29.1%; p53 stained positively and strongly with an average of 39%; none stained positively for PLAG1; and 6 out of 7 were MYB positive. CONCLUSIONS Between pleomorphic adenoma and adenoid cystic carcinoma, there was no overlap in Ki-67 positivity. Positivity for p53 showed overlap in only one lesion of each type. PLAG1 and MYB positivity were highly discriminating between pleomorphic adenoma and adenoid cystic carcinoma. Immunohistochemical analysis should be investigated further for its role in the evaluation of pleomorphic adenoma and adenoid cystic carcinoma.
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Affiliation(s)
- Pia R Mendoza
- David G. Cogan Laboratory of Ophthalmic Pathology, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts; Harvard Medical School, Boston, Massachusetts
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Proteome changes induced by c-myb silencing in human chronic myeloid leukemia cells suggest molecular mechanisms and putative biomarkers of hematopoietic malignancies. J Proteomics 2013; 96:200-22. [PMID: 24220303 DOI: 10.1016/j.jprot.2013.10.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 10/18/2013] [Accepted: 10/30/2013] [Indexed: 11/23/2022]
Abstract
UNLABELLED To shed light on the molecular mechanisms associated with aberrant accumulation of c-Myb in chronic myeloid leukemia, comparative proteomic analysis was performed on c-myb RNAi-specifically silenced K562 cells, sampled on a time-course basis. 2D-DIGE technology highlighted 37 differentially-represented proteins that were further characterized by nLC-ESI-LIT-MS/MS and validated by western blotting and qRT-PCR analysis. Most of the deregulated proteins were related to protein folding, energy/primary metabolism, transcription/translation regulation and oxidative stress response. Protein network analysis suggested that glycolysis, gluconeogenesis and protein ubiquitination biosynthesis pathways were highly represented, confirming also the pivotal role of c-Myc. A specific reduced representation was observed for glyceraldehyde-3-phosphate-dehydrogenase and α-enolase, suggesting a possible role of c-Myb in the activation of aerobic glycolysis. A reduced amount was also observed for stress responsive heat shock 70kDa protein and 78kDa glucose-regulated protein, previously identified as direct targets of c-Myb. Among over-represented proteins, worth mentioning is the chromatin modifier chromobox protein homolog 3 that contributes to silencing of E2F- and Myc-responsive genes in quiescent G0 cells. Data here presented, while providing novel insights onto the molecular mechanisms underlying c-Myb activity, indicate potential protein biomarkers for monitoring the progression of chronic myeloid leukemia. BIOLOGICAL SIGNIFICANCE Myeloid leukemia is a malignant disease of the hematopoietic system in which cells of myeloid lineages accumulate to an undifferentiated state. In particular, it was shown that an aberrant accumulation of the c-Myb transcriptional factor is associated with the suppression of normal differentiation processes promoting the development of the hematopoietic malignancies. Many efforts have been recently made to identify novel genes directly targeted by c-Myb at a transcriptome level. In this work, we originally describe a differential proteomic approach to facilitate the comprehension of the regulation of the protein networks exerted by c-Myb. Our study reveals a complex network of proteins regulated by c-Myb. The functional heterogeneity of these proteins emphasizes the pleiotropic role of c-Myb as a regulator of genes that are crucial for energy production and stress response in leukemia. In fact, variations in glyceraldehyde-3-phosphate-dehydrogenase and α-enolase suggest a possible role of c-Myb in the activation of aerobic glycolysis. Moreover, significant differences were found for heat shock 70kDa protein and 78kDa glucose-regulated protein known as direct c-Myb targets. This work highlights potential protein biomarkers to look into disease progression and to develop translational medicine approaches in myeloid leukemia.
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15
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Pattern discovery and cancer gene identification in integrated cancer genomic data. Proc Natl Acad Sci U S A 2013; 110:4245-50. [PMID: 23431203 DOI: 10.1073/pnas.1208949110] [Citation(s) in RCA: 278] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Large-scale integrated cancer genome characterization efforts including the cancer genome atlas and the cancer cell line encyclopedia have created unprecedented opportunities to study cancer biology in the context of knowing the entire catalog of genetic alterations. A clinically important challenge is to discover cancer subtypes and their molecular drivers in a comprehensive genetic context. Curtis et al. [Nature (2012) 486(7403):346-352] has recently shown that integrative clustering of copy number and gene expression in 2,000 breast tumors reveals novel subgroups beyond the classic expression subtypes that show distinct clinical outcomes. To extend the scope of integrative analysis for the inclusion of somatic mutation data by massively parallel sequencing, we propose a framework for joint modeling of discrete and continuous variables that arise from integrated genomic, epigenomic, and transcriptomic profiling. The core idea is motivated by the hypothesis that diverse molecular phenotypes can be predicted by a set of orthogonal latent variables that represent distinct molecular drivers, and thus can reveal tumor subgroups of biological and clinical importance. Using the cancer cell line encyclopedia dataset, we demonstrate our method can accurately group cell lines by their cell-of-origin for several cancer types, and precisely pinpoint their known and potential cancer driver genes. Our integrative analysis also demonstrates the power for revealing subgroups that are not lineage-dependent, but consist of different cancer types driven by a common genetic alteration. Application of the cancer genome atlas colorectal cancer data reveals distinct integrated tumor subtypes, suggesting different genetic pathways in colon cancer progression.
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Abstract
Fbw7 is a member of F-box family proteins, which constitute one subunit of Skp1, Cul1, and F-box protein (SCF) ubiquitin ligase complex. SCF(Fbw7) targets a set of well-known oncoproteins, including c-Myc, cyclin E, Notch, c-Jun, and Mcl-1, for ubiquitylation and degradation. Fbw7 provides specificity of the ubiquitylation of these substrate proteins via recognition of a consensus phosphorylated degron. Through regulation of several important proteins, Fbw7 controls diverse cellular processes, including cell-cycle progression, cell proliferation, differentiation, DNA damage response, maintenance of genomic stability, and neural cell stemness. As reduced Fbw7 expression level and loss-of-function mutations are found in a wide range of human cancers, Fbw7 is generally considered as a tumor suppressor. However, the exact mechanisms underlying Fbw7-induced tumor suppression is unclear. This review focuses on regulation network, biological functions, and genetic alteration of Fbw7 in connection with its role in cancer development.
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Affiliation(s)
- Yabin Cheng
- Department of Dermatology and Skin Science, University of British Columbia, Vancouver, V6H 3Z6, Canada
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17
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Lieu YK, Reddy EP. Impaired adult myeloid progenitor CMP and GMP cell function in conditional c-myb-knockout mice. Cell Cycle 2012; 11:3504-12. [PMID: 22918254 DOI: 10.4161/cc.21802] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The differentiation of myeloid progenitors to mature, terminally differentiated cells is a highly regulated process. Here, we showed that conditional disruption of the c-myb proto-oncogene in adult mice resulted in dramatic reductions in CMP, GMP and MEP myeloid progenitors, leading to a reduction of neutrophils, basophils, monocytes and platelets in peripheral blood. In addition, c-myb plays a critical role at multiple stages of myeloid development, from multipotent CMP and bipotent GMP to unipotent CFU-G and CFU-M progenitor cells. c-myb controls the differentiation of these cells and is required for the proper commitment, maturation and normal differentiation of CMPs and GMPs. Specifically, c-myb regulates the precise commitment to the megakaryocytic and granulo-monocytic pathways and governs the granulocytic-monocytic lineage choice. c-myb is also required for the commitment along the granulocytic pathway for early myeloid progenitor cells and for the maturation of committed precursor cells along this pathway. On the other hand, disruption of the c-myb gene favors the commitment to the monocytic lineage, although monocytic development was abnormal with cells appearing more mature with atypical CD41 surface markers. These results demonstrate that c-myb plays a pivotal role in the regulation of multiple stages in adult myelogenesis.
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Affiliation(s)
- Yen K Lieu
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY, USA.
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18
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Manzotti G, Mariani SA, Corradini F, Bussolari R, Cesi V, Vergalli J, Ferrari-Amorotti G, Fragliasso V, Soliera AR, Cattelani S, Raschellà G, Holyoake TL, Calabretta B. Expression of p89(c-Mybex9b), an alternatively spliced form of c-Myb, is required for proliferation and survival of p210BCR/ABL-expressing cells. Blood Cancer J 2012; 2:e71. [PMID: 22829973 PMCID: PMC3366069 DOI: 10.1038/bcj.2012.16] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 04/05/2012] [Indexed: 01/04/2023] Open
Abstract
The c-Myb gene encodes the p75c-Myb isoform and less-abundant proteins generated by alternatively spliced transcripts. Among these, the best known is pc-Mybex9b, which contains 121 additional amino acids between exon 9 and 10, in a domain involved in protein–protein interactions and negative regulation. In hematopoietic cells, expression of pc-Mybex9b accounts for 10–15% of total c-Myb; these levels may be biologically relevant because modest changes in c-Myb expression affects proliferation and survival of leukemic cells and lineage choice and frequency of normal hematopoietic progenitors. In this study, we assessed biochemical activities of pc-Mybex9b and the consequences of perturbing its expression in K562 and primary chronic myeloid leukemia (CML) progenitor cells. Compared with p75c-Myb, pc-Mybex9b is more stable and more effective in transactivating Myb-regulated promoters. Ectopic expression of pc-Mybex9b enhanced proliferation and colony formation and reduced imatinib (IM) sensitivity of K562 cells; conversely, specific downregulation of pc-Mybex9b reduced proliferation and colony formation, enhanced IM sensitivity of K562 cells and markedly suppressed colony formation of CML CD34+ cells, without affecting the levels of p75c-Myb. Together, these studies indicate that expression of the low-abundance pc-Mybex9b isoform has an important role for the overall biological effects of c-Myb in BCR/ABL-transformed cells.
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Bell D, Roberts D, Karpowicz M, Hanna EY, Weber RS, El-Naggar AK. Clinical significance of Myb protein and downstream target genes in salivary adenoid cystic carcinoma. Cancer Biol Ther 2011; 12:569-73. [PMID: 21785271 DOI: 10.4161/cbt.12.7.17008] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Adenoid cystic carcinoma (ACC), the second most frequent malignancy of the major and minor salivary glands, comprise of approximately 15-23% of all carcinomas at these locations. ACC is uniquely formed of dual epithelial and myoepithelial cells that give rise to different phenotypic patterns. We hypothesize that the dual myoepithelial/ epithelial composition of ACCs underlie their biological heterogeneity and may impact on their therapeutic management. A recurrent reciprocal translocation of t(6;9)(q22-23; p23-24) resulting in fusion gene partners comprising MYB gene the transcription factor NFIB has been reported in ACC of breast, salivary, lachrymal and ceruminal glands. In fusion positive and a subset of fusion negative ACCs, high expression of the transcript Myb was found. However, the role of Myb protein expression and the potential effect on the downstream targets have not been investigated. To investigate the biological and prognostic significance of use of elevated levels of Myb and its downstream target genes (c-kit, cox-2, bcl-2), we analyzed, by immunohistochemistry, the protein expression of these genes in 156 ACCs. We have found that 55% of ACCs have increased Myb expression mainly confined to myoepithelial cells. We validated Myb expression on a large cohort of ACCs (156 patients). Although no significant effects of the individual Myb and downstream targets c-kit, bcl-2 and cox-2 on survival was noticed, the combinations survival curve for Myb+/c-kit+/cox-2+ showed better survival than combination Myb-/c-kit+/cox-2+. Myb may serve as a new target for the management of this disease, and future therapeutic trials of these tumors may be better based on biomarker stratification and the cellular composition of these tumors.
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Affiliation(s)
- Diana Bell
- Department of Pathology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
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20
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Cui X, Yuan G. Formation and recognition of G-quadruplex in promoter of c-myb oncogene by electrospray ionization mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2011; 46:849-855. [PMID: 21915947 DOI: 10.1002/jms.1959] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this study, electrospray ionization mass spectrometry (ESI-MS) is used to study the formation of G-quadruplex by d(GGAGGAGGAGGA) which locates at the promoter region of c-myb gene. In addition, a natural small molecule, dehydrocorydaline from a Chinese herb, is found to have the highest binding affinity with the G-quadruplex in nine natural small molecules studied, and the binding selectivity of this natural molecule toward the c-myb G-quadruplex with respect to corresponding duplex DNA is significantly higher than that of the broad-spectrum G-quadruplex-ligand TMPyP4. The result from ESI-MS indicates that the gas-phase kinetic stability of the G-quadruplex can be enhanced by binding of dehydrocorydaline. To further investigate the binding properties of dehydrocorydaline to the G-quadruplex, Autodock3 is used to calculate the docked sites and docked energies of small molecules binding to the G-quadruplex and the result shows that the docked energy of dehydrocorydaline is the biggest in the nine small molecules used, consistent with the result from ESI-MS.
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Affiliation(s)
- Xiaojie Cui
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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Kitagawa K, Kotake Y, Hiramatsu Y, Liu N, Suzuki S, Nakamura S, Kikuchi A, Kitagawa M. GSK3 regulates the expressions of human and mouse c-Myb via different mechanisms. Cell Div 2010; 5:27. [PMID: 21092141 PMCID: PMC3001421 DOI: 10.1186/1747-1028-5-27] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 11/21/2010] [Indexed: 11/10/2022] Open
Abstract
Background c-Myb is expressed at high levels in immature progenitors of all the hematopoietic lineages. It is associated with the regulation of proliferation, differentiation and survival of erythroid, myeloid and lymphoid cells, but decreases during the terminal differentiation to mature blood cells. The cellular level of c-Myb is controlled by not only transcriptional regulation but also ubiquitin-dependent proteolysis. We recently reported that mouse c-Myb protein is controlled by ubiquitin-dependent degradation by SCF-Fbw7 E3 ligase via glycogen synthase kinase 3 (GSK3)-mediated phosphorylation of Thr-572 in a Cdc4 phosphodegron (CPD)-dependent manner. However, this critical threonine residue is not conserved in human c-Myb. In this study, we investigated whether GSK3 is involved in the regulatory mechanism for human c-Myb expression. Results Human c-Myb was degraded by ubiquitin-dependent degradation via SCF-Fbw7. Human Fbw7 ubiquitylated not only human c-Myb but also mouse c-Myb, whereas mouse Fbw7 ubiquitylated mouse c-Myb but not human c-Myb. Human Fbw7 mutants with mutations of arginine residues important for recognition of the CPD still ubiquitylated human c-Myb. These data strongly suggest that human Fbw7 ubiquitylates human c-Myb in a CPD-independent manner. Mutations of the putative GSK3 phosphorylation sites in human c-Myb did not affect the Fbw7-dependent ubiquitylation of human c-Myb. Neither chemical inhibitors nor a siRNA for GSK3β affected the stability of human c-Myb. However, depletion of GSK3β upregulated the transcription of human c-Myb, resulting in transcriptional suppression of γ-globin, one of the c-Myb target genes. Conclusions The present observations suggest that human Fbw7 ubiquitylates human c-Myb in a CPD-independent manner, whereas mouse Fbw7 ubiquitylates human c-Myb in a CPD-dependent manner. Moreover, GSK3 negatively regulates the transcriptional expression of human c-Myb but does not promote Fbw7-dependent degradation of human c-Myb protein. Inactivation of GSK3 as well as mutations of Fbw7 may be causes of the enhanced c-Myb expression observed in leukemia cells. We conclude that expression levels of human and mouse c-Myb are regulated via different mechanisms.
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Affiliation(s)
- Kyoko Kitagawa
- Department of Biochemistry 1, Hamamatsu University School of Medicine, Hamamatsu, Japan.
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The ubiquitous nature of cancer: the role of the SCF(Fbw7) complex in development and transformation. Oncogene 2010; 29:4865-73. [PMID: 20543859 DOI: 10.1038/onc.2010.222] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The ubiquitin-proteasome system (UPS) is a multi-subunit pathway that allows for ubiquitin modification of proteins and leads to either degradation or other non-proteolytic processes such as trafficking or transcriptional activation. Given its role as a regulator of cellular homeostasis it is not surprising that members of the UPS are frequently aberrantly expressed in a number of disease states including cancer. This review will focus on one member of the UPS, the F-box protein, Fbw7 (also known as Sel-10, Ago, hCDC4) and mechanisms by which Fbw7 interacts with its substrates in the context of development and tumorigenesis will be discussed. In addition, antagonists of this pathway as well as current and future therapeutics for the UPS will be examined.
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Flamant S, Ritchie W, Guilhot J, Holst J, Bonnet ML, Chomel JC, Guilhot F, Turhan AG, Rasko JEJ. Micro-RNA response to imatinib mesylate in patients with chronic myeloid leukemia. Haematologica 2010; 95:1325-33. [PMID: 20460641 DOI: 10.3324/haematol.2009.020636] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Micro-RNAs (miRNAs) control gene expression by destabilizing targeted transcripts and inhibiting their translation. Aberrant expression of miRNAs has been described in many human cancers, including chronic myeloid leukemia. Current first-line therapy for newly diagnosed chronic myeloid leukemia is imatinib mesylate, which typically produces a rapid hematologic response. However the effect of imatinib on miRNA expression in vivo has not been thoroughly examined. DESIGN AND METHODS Using a TaqMan Low-Density Array system, we analyzed miRNA expression in blood samples from newly diagnosed chronic myeloid leukemia patients before and within the first two weeks of imatinib therapy. Quantitative real-time PCR was used to validate imatinib-modulated miRNAs in sequential primary chronic myeloid leukemia samples (n=11, plus 12 additional validation patients). Bioinformatic target gene prediction analysis was performed based on changes in miRNA expression. RESULTS We observed increased expression of miR-150 and miR-146a, and reduced expression of miR-142-3p and miR-199b-5p (3-fold median change) after two weeks of imatinib therapy. A significant correlation (P<0.05) between the Sokal score and pre-treatment miR-142-3p levels was noted. Expression changes in the same miRNAs were consistently found in an additional cohort of chronic myeloid leukemia patients, as compared to healthy subjects. Peripheral blood cells from chronic phase and blast crisis patients displayed a 30-fold lower expression of miR-150 compared to normal samples, which is of particular interest since c-Myb, a known target of miR-150, was recently shown to be necessary for Bcr-Abl-mediated transformation. CONCLUSIONS We found that imatinib treatment of chronic myeloid leukemia patients rapidly normalizes the characteristic miRNA expression profile, suggesting that miRNAs may serve as a novel clinically useful biomarker in this disease.
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Affiliation(s)
- Stéphane Flamant
- Gene and Stem Cell Therapy Program, Centenary Institute, Locked Bag No 6, Newtown, NSW 2042, Australia
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Kitagawa K, Hiramatsu Y, Uchida C, Isobe T, Hattori T, Oda T, Shibata K, Nakamura S, Kikuchi A, Kitagawa M. Fbw7 promotes ubiquitin-dependent degradation of c-Myb: involvement of GSK3-mediated phosphorylation of Thr-572 in mouse c-Myb. Oncogene 2009; 28:2393-405. [PMID: 19421138 DOI: 10.1038/onc.2009.111] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Expression of oncoprotein c-Myb oscillates during hematopoiesis and hematological malignancies. Its quantity is not only regulated through transcriptional control but also through the ubiquitin-proteasome pathway, accompanied by phosphorylation, although the mechanisms are poorly understood. In this report, we tried to identify an E3 ubiquitin ligase, which targets c-Myb for ubiquitin-dependent degradation. We found that an F-box protein, Fbw7, interacted with c-Myb, which is mutated in numerous cancers. Fbw7 facilitated ubiquitylation and degradation of c-Myb in intact cells. Moreover, depletion of Fbw7 by RNA interference delayed turnover and increased the abundance of c-Myb in myeloid leukemia cells concomitantly, and suppressed the transcriptional level of gamma-globin, which receives transcriptional repression from c-Myb. In addition, we analysed sites required for both ubiquitylation and degradation of c-Myb. We found that Thr-572 is critical for Fbw7-mediated ubiquitylation in mouse c-Myb using site-directed mutagenesis. Fbw7 recognized the phosphorylation of Thr-572, which was mediated by glycogen synthase kinase 3 (GSK3). In consequence, the c-Myb protein was markedly stabilized by the substitution of Thr-572 to Ala. These observations suggest that SCF(Fbw7) ubiquitin ligase regulates phosphorylation-dependent degradation of c-Myb protein.
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Affiliation(s)
- K Kitagawa
- Department of Biochemistry 1, Hamamatsu University School of Medicine, Higashi-ku, Hamamatsu, Shizuoka, Japan.
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25
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Eijgelsheim M, Aarnoudse ALHJ, Rivadeneira F, Kors JA, Witteman JCM, Hofman A, van Duijn CM, Uitterlinden AG, Stricker BHC. Identification of a common variant at the NOS1AP locus strongly associated to QT-interval duration. Hum Mol Genet 2008; 18:347-57. [PMID: 18927126 DOI: 10.1093/hmg/ddn341] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
QT-interval prolongation is an electrophysiologic phenomenon associated with sudden cardiac death. The QT-interval in the general population is approximately 35% heritable. In genome-wide association studies, a common variant (rs10494366T > G) within the nitric oxide synthase 1 adaptor protein (NOS1AP) gene was identified and consistently associated with QT-interval duration. Yet, the causal variant remains unclear. Therefore, we performed fine mapping of the association of the NOS1AP locus with QT-interval within the Rotterdam Study, a population-based, prospective cohort study of individuals of > or =55 years of age. First, we tested the association of single-nucleotide polymorphisms (SNPs) in or within +/-100 kb of the NOS1AP gene with QT-interval duration, using sex-specific unstandardized residuals after regression on age and RR-interval, in 385 individuals using the combined set of SNPs present in the Affymetrix 500k and Illumina 550k chip arrays. Subsequently, we examined correspondence of the association signals in 4606 individuals using the Illumina 550k array. A C-to-T SNP at chromosome 1 position 160300514 (rs12143842, T-allele frequency = 24%) was associated with a QT-interval duration increase of 4.4 ms per additional T-allele (P = 4.4 x 10(-28)). For comparison, the most strongly associated variant to date, rs10494366T > G, was associated with a 3.5 ms increase (P = 1.6 x 10(-23)) per additional G-allele. None of the inferred haplotypes showed a stronger effect than the individual rs12143842C > T SNP. In conclusion, we found rs12143842 6 kb upstream distance of NOS1AP to be more strongly associated to QT-interval duration than rs10494366T > G. Functional analysis of this marker is warranted.
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Affiliation(s)
- Mark Eijgelsheim
- Department of Epidemiology, Erasmus Medical Center 3000, CA, Rotterdam, The Netherlands
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26
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Lin YC, Kuo MW, Yu J, Kuo HH, Lin RJ, Lo WL, Yu AL. c-Myb is an evolutionary conserved miR-150 target and miR-150/c-Myb interaction is important for embryonic development. Mol Biol Evol 2008; 25:2189-98. [PMID: 18667440 DOI: 10.1093/molbev/msn165] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Human c-Myb proto-oncogene is highly expressed in hematopoietic progenitors as well as leukemia and certain solid tumor. However, the regulatory mechanisms of its expression and biological functions remain largely unclear. Recently, c-Myb has been shown to be targeted by microRNA-150 (miR-150) which thereby controls B cell differentiation in mice. In this study, we demonstrated that c-Myb is an evolutionary conserved target of miR-150 in human and zebrafish, using reporter assays. Ectopic expression of miR-150 in breast cancer and leukemic cells repressed endogenous c-Myb at both messenger RNA (mRNA) and protein levels. Among several leukemia cell lines, primary leukemia cells, and normal lymphocytes, expression levels of miR-150 inversely correlated with c-Myb. The miR-150 overexpression or c-Myb silencing in zebrafish zygotes led to similar and serious phenotypic defects in zebrafish, and the phenotypic aberrations induced by miR-150 could be reversed by coinjection of c-Myb mRNA. Our findings suggest that c-Myb is an evolutionally conserved target of miR-150 and miR-150/c-Myb interaction is important for embryonic development and possibly oncogenesis.
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Affiliation(s)
- You-Chin Lin
- Genomics Research Center, Academia Sinica Taipei, Taiwan
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27
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Park JS, Kim JB, Cho KJ, Cheon CI, Sung MK, Choung MG, Roh KH. Arabidopsis R2R3-MYB transcription factor AtMYB60 functions as a transcriptional repressor of anthocyanin biosynthesis in lettuce (Lactuca sativa). PLANT CELL REPORTS 2008; 27:985-94. [PMID: 18317777 PMCID: PMC2413084 DOI: 10.1007/s00299-008-0521-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2007] [Revised: 01/30/2008] [Accepted: 02/17/2008] [Indexed: 05/18/2023]
Abstract
The MYB transcription factors play important roles in the regulation of many secondary metabolites at the transcriptional level. We evaluated the possible roles of the Arabidopsis R2R3-MYB transcription factors in flavonoid biosynthesis because they are induced by UV-B irradiation but their associated phenotypes are largely unexplored. We isolated their genes by RACE-PCR, and performed transgenic approach and metabolite analyses in lettuce (Lactuca sativa). We found that one member of this protein family, AtMYB60, inhibits anthocyanin biosynthesis in the lettuce plant. Wild-type lettuce normally accumulates anthocyanin, predominantly cyanidin and traces of delphinidin, and develops a red pigmentation. However, the production and accumulation of anthocyanin pigments in AtMYB60-overexpressing lettuce was inhibited. Using RT-PCR analysis, we also identified the complete absence or reduction of dihydroflavonol 4-reductase (DFR) transcripts in AtMYB60- overexpressing lettuce (AtMYB60-117 and AtMYB60-112 lines). The correlation between the overexpression of AtMYB60 and the inhibition of anthocyanin accumulation suggests that the transcription factorAtMYB60 controls anthocyanin biosynthesis in the lettuce leaf. Clarification of the roles of the AtMYB60 transcription factor will facilitate further studies and provide genetic tools to better understand the regulation in plants of the genes controlled by the MYB-type transcription factors. Furthermore, the characterization of AtMYB60 has implications for the development of new varieties of lettuce and other commercially important plants with metabolic engineering approaches.
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Affiliation(s)
- Jong-Sug Park
- Molecular Physiology and Biochemistry Division, National Institute of Agricultural Biotechnology, Suwon, 441-707 South Korea
| | - Jung-Bong Kim
- Molecular Physiology and Biochemistry Division, National Institute of Agricultural Biotechnology, Suwon, 441-707 South Korea
| | - Kang-Jin Cho
- Molecular Physiology and Biochemistry Division, National Institute of Agricultural Biotechnology, Suwon, 441-707 South Korea
| | - Choong-Ill Cheon
- Department of Life Science, Sookmyung Women’s University, Youngsan-gu, Seoul, 140-742 South Korea
| | - Mi-Kyung Sung
- Department of Food and Nutrition, Sookmyung Women’s University, Youngsan-gu, Seoul, 140-742 South Korea
| | - Myoung-Gun Choung
- Department of Pharmacognosy Material Development, Kangwon National University, Samcheok, 245-711 South Korea
| | - Kyung-Hee Roh
- Molecular Physiology and Biochemistry Division, National Institute of Agricultural Biotechnology, Suwon, 441-707 South Korea
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28
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Qin Y, Hurley LH. Structures, folding patterns, and functions of intramolecular DNA G-quadruplexes found in eukaryotic promoter regions. Biochimie 2008; 90:1149-71. [PMID: 18355457 DOI: 10.1016/j.biochi.2008.02.020] [Citation(s) in RCA: 373] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 02/22/2008] [Indexed: 12/16/2022]
Abstract
In its simplest form, a DNA G-quadruplex is a four-stranded DNA structure that is composed of stacked guanine tetrads. G-quadruplex-forming sequences have been identified in eukaryotic telomeres, as well as in non-telomeric genomic regions, such as gene promoters, recombination sites, and DNA tandem repeats. Of particular interest are the G-quadruplex structures that form in gene promoter regions, which have emerged as potential targets for anticancer drug development. Evidence for the formation of G-quadruplex structures in living cells continues to grow. In this review, we examine recent studies on intramolecular G-quadruplex structures that form in the promoter regions of some human genes in living cells and discuss the biological implications of these structures. The identification of G-quadruplex structures in promoter regions provides us with new insights into the fundamental aspects of G-quadruplex topology and DNA sequence-structure relationships. Progress in G-quadruplex structural studies and the validation of the biological role of these structures in cells will further encourage the development of small molecules that target these structures to specifically modulate gene transcription.
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Affiliation(s)
- Yong Qin
- College of Pharmacy, 1703 E. Mabel, University of Arizona, Tucson, AZ 85721, USA
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29
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Palumbo SL, Memmott RM, Uribe DJ, Krotova-Khan Y, Hurley LH, Ebbinghaus SW. A novel G-quadruplex-forming GGA repeat region in the c-myb promoter is a critical regulator of promoter activity. Nucleic Acids Res 2008; 36:1755-69. [PMID: 18252774 PMCID: PMC2330228 DOI: 10.1093/nar/gkm1069] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The c-myb promoter contains multiple GGA repeats beginning 17 bp downstream of the transcription initiation site. GGA repeats have been previously shown to form unusual DNA structures in solution. Results from chemical footprinting, circular dichroism and RNA and DNA polymerase arrest assays on oligonucleotides representing the GGA repeat region of the c-myb promoter demonstrate that the element is able to form tetrad:heptad:heptad:tetrad (T:H:H:T) G-quadruplex structures by stacking two tetrad:heptad G-quadruplexes formed by two of the three (GGA)(4) repeats. Deletion of one or two (GGA)(4) motifs destabilizes this secondary structure and increases c-myb promoter activity, indicating that the G-quadruplexes formed in the c-myb GGA repeat region may act as a negative regulator of the c-myb promoter. Complete deletion of the c-myb GGA repeat region abolishes c-myb promoter activity, indicating dual roles of the c-myb GGA repeat element as both a transcriptional repressor and an activator. Furthermore, we demonstrated that Myc-associated zinc finger protein (MAZ) represses c-myb promoter activity and binds to the c-myb T:H:H:T G-quadruplexes. Our findings show that the T:H:H:T G-quadruplex-forming region in the c-myb promoter is a critical cis-acting element and may repress c-myb promoter activity through MAZ interaction with G-quadruplexes in the c-myb promoter.
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Affiliation(s)
- SunMi L Palumbo
- Arizona Cancer Center, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ 85724-5024, USA
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30
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Malaterre J, Mantamadiotis T, Dworkin S, Lightowler S, Yang Q, Ransome MI, Turnley AM, Nichols NR, Emambokus NR, Frampton J, Ramsay RG. c-Myb is required for neural progenitor cell proliferation and maintenance of the neural stem cell niche in adult brain. Stem Cells 2007; 26:173-81. [PMID: 17901403 DOI: 10.1634/stemcells.2007-0293] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ongoing production of neurons in adult brain is restricted to specialized neurogenic niches. Deregulated expression of genes controlling homeostasis of neural progenitor cell division and/or their microenvironment underpins a spectrum of brain pathologies. Using conditional gene deletion, we show that the proto-oncogene c-myb regulates neural progenitor cell proliferation and maintains ependymal cell integrity in mice. These two cellular compartments constitute the neurogenic niche in the adult brain. Brains devoid of c-Myb showed enlarged ventricular spaces, ependymal cell abnormalities, and reduced neurogenesis. Neural progenitor cells lacking c-Myb showed a reduced intrinsic proliferative capacity and reduction of Sox-2 and Pax-6 expression. These data point to an important role for c-Myb in the neurogenic niche of the adult brain.
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Affiliation(s)
- Jordane Malaterre
- Differentiation and Transcription Laboratory, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
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31
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Corradini F, Bussolari R, Cerioli D, Lidonnici MR, Calabretta B. A degradation-resistant c-Myb mutant cooperates with Bcl-2 in enhancing proliferative potential and survival of hematopoietic cells. Blood Cells Mol Dis 2007; 39:292-6. [PMID: 17644012 PMCID: PMC4274770 DOI: 10.1016/j.bcmd.2007.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 06/08/2007] [Indexed: 10/23/2022]
Abstract
The c-myb gene is preferentially expressed in primitive hematopoietic cell and plays a central role in the control of cell proliferation, differentiation and survival by regulating the transcription of several genes implicated in these processes including the antiapoptotic Bcl-2. We show here that, compared to wild-type c-Myb, overexpression of a degradation resistant c-Myb mutant [Delta(358-452) c-Myb] enhances the clonogenic potential of hematopoietic progenitors as indicated by increased cytokine-dependent primary and secondary colony formation of Lin(-) Sca-1(+) Kit(+) mouse marrow cells. Moreover, proliferation assays of IL-3 dependent myeloid precursor 32Dcl3 cells co-expressing Bcl-2 and c-Myb indicate that these cells continue to proliferate in the absence of IL-3 and this effect is more apparent in cells expressing the degradation resistant Delta(358-452) c-Myb. Interestingly, overexpression of Delta(358-452) c-Myb is by itself sufficient to protect 32Dcl3 cells from apoptosis induced by IL-3 deprivation; moreover, these cells are also increased in number which most likely reflects the enhanced proliferative potential conferred by Delta(358-452) c-Myb to apoptosis-resistant cells.
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Affiliation(s)
- Francesca Corradini
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson Medical College, Philadelphia, PA, USA.
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32
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Clappier E, Cuccuini W, Kalota A, Crinquette A, Cayuela JM, Dik WA, Langerak AW, Montpellier B, Nadel B, Walrafen P, Delattre O, Aurias A, Leblanc T, Dombret H, Gewirtz AM, Baruchel A, Sigaux F, Soulier J. The C-MYB locus is involved in chromosomal translocation and genomic duplications in human T-cell acute leukemia (T-ALL), the translocation defining a new T-ALL subtype in very young children. Blood 2007; 110:1251-61. [PMID: 17452517 DOI: 10.1182/blood-2006-12-064683] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The C-Myb transcription factor is essential for hematopoiesis, including in the T-cell lineage. The C-Myb locus is a common site of retroviral insertional mutagenesis, however no recurrent genomic involvement has been reported in human malignancies. Here, we identified 2 types of genomic alterations involving the C-MYB locus at 6q23 in human T-cell acute leukemia (T-ALL). First, we found a reciprocal translocation, t(6;7)(q23;q34), that juxtaposed the TCRB and C-MYB loci (n = 6 cases). Second, a genome-wide copy-number analysis by array-based comparative genomic hybridization (array-CGH) identified short somatic duplications that include C-MYB (MYB(dup), n = 13 cases of 84 T-ALL, 15%). Expression analysis, including allele-specific approaches, showed stronger C-MYB expression in the MYB-rearranged cases compared with other T-ALLs, and a dramatically skewed C-MYB allele expression in the TCRB-MYB cases, which suggests that a translocation-driven deregulated expression may overcome a cellular attempt to down-regulate C-MYB. Strikingly, profiling of the T-ALLs by clinical, genomic, and large-scale gene expression analyses shows that the TCRB-MYB translocation defines a new T-ALL subtype associated with a very young age for T-cell leukemia (median, 2.2 years) and with a proliferation/mitosis expression signature. By contrast, the MYB(dup) alteration was associated with the previously defined T-ALL subtypes.
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Affiliation(s)
- Emmanuelle Clappier
- Genome Rearrangements and Cancer Group, Institut National de la Santé et de la Recherche Médicale U728 and Institut Universitaire d'Hématologie, Paris 7 University, Hôpital Saint-Louis, Paris, France
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33
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Lutwyche JK, Keough RA, Hunter J, Coles LS, Gonda TJ. DNA binding-independent transcriptional activation of the vascular endothelial growth factor gene (VEGF) by the Myb oncoprotein. Biochem Biophys Res Commun 2006; 344:1300-7. [PMID: 16650815 DOI: 10.1016/j.bbrc.2006.04.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Accepted: 04/12/2006] [Indexed: 11/26/2022]
Abstract
Myb is a key transcription factor that can regulate proliferation, differentiation, and apoptosis, predominantly in the haemopoietic system. Abnormal expression of Myb is associated with a number of cancers, both haemopoietic and non-haemopoietic. In order to better understand the role of Myb in normal and tumorigenic processes, we undertook a cDNA array screen to identify genes that are regulated by this factor. In this way, we identified the gene encoding vascular endothelial growth factor (VEGF) as being potentially regulated by the Myb oncoprotein in myeloid cells. To determine whether this was a direct effect on VEGF gene transcription, we examined the activity of the murine VEGF promoter in the presence of either wild-type (WT) or mutant forms of Myb. It was found that WT Myb was able to activate the VEGF promoter and that a minimal promoter region of 120 bp was sufficient to confer Myb responsiveness. Surprisingly, activation of the VEGF promoter was independent of DNA binding by Myb. This was shown by the use of DNA binding-defective Myb mutants and by mutagenesis of a potential Myb-binding site in the minimal promoter. Mutation of Sp1 sites within this region abolished Myb-mediated regulation of a reporter construct, suggesting that Myb DNA binding-independent activation of VEGF expression occurs via these Sp1 binding elements. Regulation of VEGF production by Myb has implications for the potential role of Myb in myeloid leukaemias and in solid tumours where VEGF may be functioning as an autocrine growth factor.
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Affiliation(s)
- Jodi K Lutwyche
- Division of Human Immunology and Hanson Institute, Institute of Medical and Veterinary Science, Frome Road, Adelaide, SA 5000, Australia
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34
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Steensma DP, Pardanani A, Stevenson WS, Hoyt R, Kiu H, Grigg AP, Szer J, Juneja S, Hilton DJ, Alexander WS, Roberts AW. More on Myb in myelofibrosis: molecular analyses of MYB and EP300 in 55 patients with myeloproliferative disorders. Blood 2006; 107:1733-5; author reply 1735. [PMID: 16461764 PMCID: PMC1895422 DOI: 10.1182/blood-2005-09-3646] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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35
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Davis JN, McCabe MT, Hayward SW, Park JM, Day ML. Disruption of Rb/E2F pathway results in increased cyclooxygenase-2 expression and activity in prostate epithelial cells. Cancer Res 2005; 65:3633-42. [PMID: 15867358 DOI: 10.1158/0008-5472.can-04-3129] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The loss of the retinoblastoma tumor suppressor gene (RB) is common in many human cancers, including prostate. We previously reported that engineered deletion of RB in prostate epithelial cells results in sustained cell growth in serum-free media, a predisposition to develop hyperplasia and dysplasia in prostate tissue recombinant grafts, and sensitization to hormonal carcinogenesis. Examining the molecular consequence of RB loss in this system, we show that cyclooxygenase-2 (COX-2) is significantly up-regulated following RB deletion in prostate tissue recombinants. To study the effect of RB deletion on COX-2 regulation, we generated wild-type (PrE) and Rb-/- (Rb-/-PrE) prostate epithelial cell lines rescued by tissue recombination. We show elevated COX-2 mRNA and protein expression in Rb-/-PrE cell lines with increased prostaglandin synthesis. We also find that loss of Rb leads to deregulated E2F activity, with increased expression of E2F target genes, and that exogenous expression of E2F1 results in elevated COX-2 mRNA and protein levels. COX-2 promoter studies reveal that E2F1 transcriptionally activates COX-2, which is dependent on the transactivation and DNA-binding domains of E2F1. Further analysis revealed that the E2F1 target gene, c-myb, is elevated in Rb-/-PrE cells and E2F1-overexpressing cells, whereas ectopic overexpression of c-myb activates the COX-2 promoter in prostate epithelial cells. Additionally, cotransfection with E2F1 and a dominant-negative c-myb inhibited E2F1 activation of the COX-2 promoter. Taken together, these results suggest activation of a transcriptional cascade by which E2F1 regulates COX-2 expression through the c-myb oncogene. This study reports a novel finding describing that deregulation of the Rb/E2F complex results in increased COX-2 expression and activity.
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Affiliation(s)
- Joanne N Davis
- Department of Urology, Michigan Urology Center, University of Michigan, Ann Arbor, Michigan 48109-0944, USA
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36
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Mehrtens F, Kranz H, Bednarek P, Weisshaar B. The Arabidopsis transcription factor MYB12 is a flavonol-specific regulator of phenylpropanoid biosynthesis. PLANT PHYSIOLOGY 2005; 138:1083-96. [PMID: 15923334 PMCID: PMC1150422 DOI: 10.1104/pp.104.058032] [Citation(s) in RCA: 515] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Comprehensive functional data on plant R2R3-MYB transcription factors is still scarce compared to the manifold of their occurrence. Here, we identified the Arabidopsis (Arabidopsis thaliana) R2R3-MYB transcription factor MYB12 as a flavonol-specific activator of flavonoid biosynthesis. Transient expression in Arabidopsis protoplasts revealed a high degree of functional similarity between MYB12 and the structurally closely related factor P from maize (Zea mays). Both displayed similar target gene specificity, and both activated target gene promoters only in the presence of a functional MYB recognition element. The genes encoding the flavonoid biosynthesis enzymes chalcone synthase, chalcone flavanone isomerase, flavanone 3-hydroxylase, and flavonol synthase were identified as target genes. Hence, our observations further add to the general notion of a close relationship between structure and function of R2R3-MYB factors. High-performance liquid chromatography analyses of myb12 mutant plants and MYB12 overexpression plants demonstrate a tight linkage between the expression level of functional MYB12 and the flavonol content of young seedlings. Quantitative real time reverse transcription-PCR using these mutant plants showed MYB12 to be a transcriptional regulator of CHALCONE SYNTHASE and FLAVONOL SYNTHASE in planta, the gene products of which are indispensable for the biosynthesis of flavonols.
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Affiliation(s)
- Frank Mehrtens
- Max-Planck-Institute for Plant Breeding Research, D-50829 Cologne, Germany
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37
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Corradini F, Cesi V, Bartella V, Pani E, Bussolari R, Candini O, Calabretta B. Enhanced proliferative potential of hematopoietic cells expressing degradation-resistant c-Myb mutants. J Biol Chem 2005; 280:30254-62. [PMID: 15927960 DOI: 10.1074/jbc.m504703200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The c-myb gene encodes a transcription factor required for proliferation, differentiation, and survival of hematopoietic cells. Expression of c-Myb is often increased in hematological malignancies, but the underlying mechanisms are poorly understood. We show here that c-Myb has a longer half-life (at least 2-fold) in BCR/ABL-expressing than in normal hematopoietic cells. Such enhanced stability was dependent on a phosphatidylinositol 3-kinase (PI-3K)/Akt/GSKIIIbeta pathway(s) as indicated by the suppression of c-Myb expression upon treatment with PI-3K inhibitors or co-expression with dominant negative Akt or constitutively active GSKIIIbeta. Moreover, inhibition of GSKIIIbeta by LiCl enhanced c-Myb expression in parental 32Dcl3 cells. Compared with wild type c-Myb, three mutants (delta(358-452), delta(389-418), and L389A/L396A c-Myb) of the leucine zipper domain had increased stability. However, only expression of delta(358-452) was not affected by inhibition of the PI-3K/Akt pathway and was not enhanced by a proteasome inhibitor, suggesting that leucine zipper-dependent and -independent mechanisms are involved in the regulation of c-Myb stability. Indeed, delta(389-418) carrying four lysine-to-alanine substitutions (delta(389-418) K387A/K428A/K442A/K445A) was as stable as delta(358-452) c-Myb. Compared with full-length c-Myb, constitutive expression of delta(358-452) and delta(389-418) c-Myb in Lin-Sca-1+ mouse marrow cells increased cytokine-dependent primary and secondary colony formation. In K562 cells, expression of delta(358-452), delta(389-418), and L389A/L396A c-Myb led to enhanced proliferation after STI571 treatment. Thus, enhanced stability of c-Myb by activation of PI-3K-dependent pathway(s) might contribute to the higher proliferative potential of BCR/ABL-expressing and, perhaps, other leukemic cells.
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Affiliation(s)
- Francesca Corradini
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson Medical College, Philadelphia, Pennsylvania 19107, USA
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Close J, Game L, Clark B, Bergounioux J, Gerovassili A, Thein SL. Genome annotation of a 1.5 Mb region of human chromosome 6q23 encompassing a quantitative trait locus for fetal hemoglobin expression in adults. BMC Genomics 2004; 5:33. [PMID: 15169551 PMCID: PMC441375 DOI: 10.1186/1471-2164-5-33] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2004] [Accepted: 05/31/2004] [Indexed: 12/24/2022] Open
Abstract
Background Heterocellular hereditary persistence of fetal hemoglobin (HPFH) is a common multifactorial trait characterized by a modest increase of fetal hemoglobin levels in adults. We previously localized a Quantitative Trait Locus for HPFH in an extensive Asian-Indian kindred to chromosome 6q23. As part of the strategy of positional cloning and a means towards identification of the specific genetic alteration in this family, a thorough annotation of the candidate interval based on a strategy of in silico / wet biology approach with comparative genomics was conducted. Results The ~1.5 Mb candidate region was shown to contain five protein-coding genes. We discovered a very large uncharacterized gene containing WD40 and SH3 domains (AHI1), and extended the annotation of four previously characterized genes (MYB, ALDH8A1, HBS1L and PDE7B). We also identified several genes that do not appear to be protein coding, and generated 17 kb of novel transcript sequence data from re-sequencing 97 EST clones. Conclusion Detailed and thorough annotation of this 1.5 Mb interval in 6q confirms a high level of aberrant transcripts in testicular tissue. The candidate interval was shown to exhibit an extraordinary level of alternate splicing – 19 transcripts were identified for the 5 protein coding genes, but it appears that a significant portion (14/19) of these alternate transcripts did not have an open reading frame, hence their functional role is questionable. These transcripts may result from aberrant rather than regulated splicing.
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Affiliation(s)
- James Close
- Department of Haematological Medicine, GKT School of Medicine, King's Denmark Hill Campus, Bessemer Road, London, SE5 9PJ, UK
- SANE POWIC, Warneford Hospital, Department of Psychiatry, University of Oxford, Oxford, OX3 7JX, UK
| | - Laurence Game
- Department of Haematological Medicine, GKT School of Medicine, King's Denmark Hill Campus, Bessemer Road, London, SE5 9PJ, UK
- CSC-IC Microarray Centre, 2nd floor, L-block, Room 221, Imperial College Faculty of Medicine, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Barnaby Clark
- Department of Haematological Medicine, GKT School of Medicine, King's Denmark Hill Campus, Bessemer Road, London, SE5 9PJ, UK
| | - Jean Bergounioux
- Department of Haematological Medicine, GKT School of Medicine, King's Denmark Hill Campus, Bessemer Road, London, SE5 9PJ, UK
- Unité de soins intensif pédiatrique, Hôpital Universitaire Krémlin Bicêtre, 63 av. Gabriel Péri, 94270 Le Krémlin Bicêtre, France
| | - Ageliki Gerovassili
- Department of Haematological Medicine, GKT School of Medicine, King's Denmark Hill Campus, Bessemer Road, London, SE5 9PJ, UK
| | - Swee Lay Thein
- Department of Haematological Medicine, GKT School of Medicine, King's Denmark Hill Campus, Bessemer Road, London, SE5 9PJ, UK
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Van Dijk JP, Knops GHJN, Van De Locht LTF, Menke AL, Jansen JH, Mensink EJBM, Raymakers RAP, De Witte T. Abnormal WT1 expression in the CD34-negative compartment in myelodysplastic bone marrow. Br J Haematol 2002; 118:1027-33. [PMID: 12199781 DOI: 10.1046/j.1365-2141.2002.03728.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In normal bone marrow, WT1 expression is restricted to CD34+ cells. We assessed WT1 mRNA expression levels with quantitative, real-time reverse transcription polymerase chain reaction in normal, myelodysplastic (MDS) and secondary acute myeloid leukaemia (sAML) bone marrow subfractions, based on differentiation status. The highest WT1 expression was observed in the primitive CD34+ rhodamine-123 (rho) dull cells, both in healthy donors and MDS or sAML patients. In contrast to normal CD34-negative bone marrow cells, WT1 was present in CD34-negative bone marrow cells in 12 out of 13 MDS patients and two sAML samples. Further analysis of this aberrant WT1 expression was performed in the CD34-negative subfractions of three MDS patients. In one of these, WT1 expression was found exclusively in the erythroid cells. This patient was completely transfusion dependent and showed morphological dyserythropoiesis. In another MDS patient, WT1 expression was found in a non-erythroid compartment. We conclude that abnormal WT1 expression may contribute to the disturbed differentiation of haematopoietic cells in MDS patients.
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Affiliation(s)
- Jeroen P Van Dijk
- Central Haematology Laboratory, University Medical Centre, St. Radboud, Nijmegen, The Netherlands
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40
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Lutwyche JK, Keough RA, Hughes TP, Gonda TJ. Mutation screening of the c-MYB negative regulatory domain in acute and chronic myeloid leukaemia. Br J Haematol 2001; 114:632-4. [PMID: 11552989 DOI: 10.1046/j.1365-2141.2001.02966.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Over-expression of the c-myb gene and expression of activated forms of myb are known to transform haemopoietic cells, particularly cells of the myeloid lineage. Truncations or mutations that disrupt the negative regulatory domain (NRD) of the Myb protein confer an increased ability to transform cells. Although it has proved difficult to link mutations in c-MYB to human leukaemia, no studies investigating the presence of mutations within the c-MYB NRD have been reported. Therefore, we have performed mutational analysis of this region, using polymerase chain reaction-single-stranded conformation polymorphism and sequence analysis, in 26 patients with acute or chronic myeloid leukaemia. No mutations were detected, indicating that mutation of this region of the Myb protein is not common in the pathogenesis or progression of these diseases.
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Affiliation(s)
- J K Lutwyche
- Hanson Centre for Cancer Research, Division of Human Immunology, Institute of Medical and Veterinary Science, Adelaide, Australia
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41
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Cures A, House C, Kanei-Ishii C, Kemp B, Ramsay RG. Constitutive c-Myb amino-terminal phosphorylation and DNA binding activity uncoupled during entry and passage through the cell cycle. Oncogene 2001; 20:1784-92. [PMID: 11313925 DOI: 10.1038/sj.onc.1204345] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2000] [Revised: 02/01/2001] [Accepted: 02/05/2001] [Indexed: 12/28/2022]
Abstract
The c-myb gene encodes a transcription factor that is central to hematopoietic cell growth. Phosphorylation of c-Myb by casein kinase 2 (CK2) at serines 11 and 12 has been variously implicated in the regulation of DNA binding. However, it is unclear when c-Myb phosphorylation at serines 11 and 12 occurs during the cell cycle and how this is regulated. We generated specific antisera that recognize phosphoserines 11 and 12 of c-Myb. C-Myb protein levels, extent of CK2 phosphorylation and DNA binding were then monitored following mitogenic stimulus and passage through the cell cycle in normal peripheral T-cells and the T leukemia cell line CCRF-CEM. We found that endogenous c-Myb is constitutively phosphorylated at serines 11 and 12. The amount of phosphorylated c-Myb correlates with DNA binding activity in cycling CEM cells but not upon entry of T-cells into the cell cycle. Exogenous expression of c-Myb with substitutions of serines 11 and 12 with glutamic acid or alanine had no effect on the transactivation of a c-Myb responsive reporter. These data strongly suggest that c-Myb is constitutively phosphorylated on serines 11 and 12 by CK2 or like activity and is not regulated during the cell cycle.
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Affiliation(s)
- A Cures
- Trescowthick Research Laboratories, Peter MacCallum Cancer Institute, Melbourne, Vic. Australia
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42
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Campanero MR, Armstrong M, Flemington E. Distinct cellular factors regulate the c-myb promoter through its E2F element. Mol Cell Biol 1999; 19:8442-50. [PMID: 10567569 PMCID: PMC84947 DOI: 10.1128/mcb.19.12.8442] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Most E2F-driven promoters are transiently activated around the G(1)/S transition. Although the promoter for the c-myb proto-oncogene harbors an E2F element, it is induced early in G(1) following entry into the cell cycle. Furthermore, this promoter remains active throughout subsequent cell cycles. Since E2F sites function as repressor elements during G(1) (due to the association of pRb with E2F factors), we investigated whether the E2F element in the c-myb promoter is regulated differently than E2F elements in promoters that are repressed during G(1). By gel shift analysis, the E2F element from the c-myb promoter was found to form a unique complex, referred to as E2Fmyb-sp, which was not observed with E2F elements from several other promoters. Antibodies to DP-1, E2F1 to -5, p107, or pRb failed to either supershift or block E2Fmyb-sp complex formation. Methylation interference experiments indicate that the DNA contact residues for the E2Fmyb-sp complex are distinct from but overlapping with residues required for the binding of E2F proteins. In addition to the identification of E2Fmyb-sp, we have found that SP-1 binds to the c-myb E2F element. Functional studies revealed that E2Fmyb-sp and/or SP-1 are required to achieve full activation of the c-myb promoter in different cell types and to maintain elevated expression of the c-myb promoter during G(1) in NIH 3T3 cells. These studies demonstrate that E2F elements can be regulated differently through the binding of unique sets of proteins.
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Affiliation(s)
- M R Campanero
- Harvard University and Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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43
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Gewirtz AM. The c-myb Protooncogene: A Novel Target for Human Gene Therapy. Gene Ther 1999. [DOI: 10.1007/978-3-0348-7011-5_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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44
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Kasono K, Piché A, Xiang J, Kim HG, Bilbao G, Johanning F, Nawrath M, Moelling K, Curiel DT. Functional knock-out of c-myb by an intracellular anti-c-Myb single-chain antibody. Biochem Biophys Res Commun 1998; 251:124-30. [PMID: 9790918 DOI: 10.1006/bbrc.1998.9259] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aberrant expression of the c-myb proto-oncogene is a key factor in the development of the neoplastic phenotype in a variety of contexts. On this basis, it has been proposed that ablation of c-myb function might be an effective approach for therapy. To this end, we have employed an intracellular single-chain antibody (sFv) approach to achieve the functional knock-out of the c-Myb onco-protein. We derived an anti-c-Myb sFv, which was configured into eukaryotic expression plasmids. We confirmed the expression of the cytoplasmic and nuclear forms of the sFvs in the correct subcellular compartments by immunofluorescent staining. Importantly, the anti-c-Myb sFvs strongly inhibited the transactivation activity of c-Myb. Furthermore, cytotoxic effect of the sFv was observed only in the c-Myb positive cell line K562. These results suggest that anti-c-Myb sFv is a valuable tool for understanding the molecular mechanisms of c-myb induced transformation. In addition, this approach may have potential utility in the gene therapy for c-myb-dependent malignant diseases.
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Affiliation(s)
- K Kasono
- Gene Therapy Program, University of Alabama at Birmingham, 1824 6th Avenue South, WTI620, Birmingham, Alabama, 35294, USA
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45
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Wong MW, Henry RW, Ma B, Kobayashi R, Klages N, Matthias P, Strubin M, Hernandez N. The large subunit of basal transcription factor SNAPc is a Myb domain protein that interacts with Oct-1. Mol Cell Biol 1998; 18:368-77. [PMID: 9418884 PMCID: PMC121507 DOI: 10.1128/mcb.18.1.368] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/1997] [Accepted: 10/08/1997] [Indexed: 02/05/2023] Open
Abstract
The human RNA polymerase II and III snRNA promoters have similar enhancers, the distal sequence elements (DSEs), and similar basal promoter elements, the proximal sequence elements (PSEs). The DSE, which contains an octamer motif, binds broadly expressed activator Oct-1. The PSE binds a multiprotein complex referred to as SNAPc or PTF. On DNAs containing both an octamer site and a PSE, Oct-1 and SNAPc bind cooperatively. SNAPc consists of at least four stably associated subunits, SNAP43, SNAP45, SNAP50, and SNAP190. None of the three small subunits, which have all been cloned, can bind to the PSE on their own. Here we report the isolation of cDNAs corresponding to the largest subunit of SNAPc, SNAP190. SNAP190 contains an unusual Myb DNA binding domain consisting of four complete repeats (Ra to Rd) and a half repeat (Rh). A truncated protein consisting of the last two SNAP190 Myb repeats, Rc and Rd, can bind to the PSE, suggesting that the SNAP190 Myb domain contributes to recognition of the PSE by the SNAP complex. SNAP190 is required for snRNA gene transcription by both RNA polymerases II and III and interacts with SNAP45. In addition, SNAP190 interacts with Oct-1. Together, these results suggest that the largest subunit of the SNAP complex is involved in direct recognition of the PSE and is a target for the Oct-1 activator. They also provide an example of a basal transcription factor containing a Myb DNA binding domain.
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Affiliation(s)
- M W Wong
- Cold Spring Harbor Laboratory and Howard Hughes Medical Institute, New York 11724, USA
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46
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Williams CE, Grotewold E. Differences between plant and animal Myb domains are fundamental for DNA binding activity, and chimeric Myb domains have novel DNA binding specificities. J Biol Chem 1997; 272:563-71. [PMID: 8995298 DOI: 10.1074/jbc.272.1.563] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Several Myb domain proteins have been identified in plants, in which they play important regulatory roles in specific cellular processes. Plant and animal Myb domains have significant differences, but how these differences are important for function is not yet understood. The P gene encodes a Myb domain protein that activates a subset of flavonoid biosynthetic genes in maize floral organs. P and v-Myb bind different DNA sequences in vitro. Here we show that the Myb domain is solely responsible for the sequence-specific DNA binding activity of P, which binds DNA only in the reduced state. Differences in the DNA binding domains of v-Myb and P, which are conserved among animal and plant Myb domains, are fundamental for the high affinity DNA binding activity of these proteins to the corresponding binding sites but are not sufficient for the distinct DNA binding specificities of P and v-Myb. We conclude that significant structural differences distinguish plant from animal Myb domains. A chimeric Myb domain with a novel DNA binding specificity was created by combining Myb repeats of P and v-Myb. This approach could be used to artificially create novel Myb domains and to target transcription factors to genes containing specific promoters or to modify Myb-mediated interactions with other cellular factors.
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Affiliation(s)
- C E Williams
- Dowling College, Oakdale, New York 11769-1999, USA
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Dooley S, Seib T, Welter C, Blin N. c-myb intron I protein binding and association with transcriptional activity in leukemic cells. Leuk Res 1996; 20:429-39. [PMID: 8683983 DOI: 10.1016/0145-2126(96)00012-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Specific binding of nuclear proteins to the region of transcriptional attenuation has been shown to modulate the expression of c-myb, a nuclear proto-oncogene preferentially expressed in lympho-hematopoietic cells. Here, it plays an important role in processes of differentiation and proliferation. The mechanism that regulates c-myb expression is not yet fully understood. The block of transcriptional elongation which has been mapped to a 1 kb region within murine intron 1 may represent one regulatory pathway. The DNA sequences containing the transcriptional pause site are well conserved between murine and human species, thus Implying similar transcription-control strategies. We compared the binding potential of nuclear extracts (from human fibroblasts and MOLT4 as well as murine NIH3T3- and 70Z/3B- cell lines) to oligonucleotide sequences previously shown to be target binding sites in the murine system. One complex containing a 70 D protein was found to be associated specifically with transcriptionally active leukemia cells. We performed transient expression studies with a CAT reporter construct containing this putative enhancer sequence and yielded significant CAT activity. We identified further a putative 20 kD repressor protein in transcriptionally silent cells and demonstrated that c-Jun is part of an ubiquitously present complex. Our results confirm the participation of intron 1 in transcriptional regulation of the c-myb gene (in mouse and human) and implicate multiple and complex regulatory mechanisms of activation during myelomonocytic differentiation and leukemic cell growth control.
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Affiliation(s)
- S Dooley
- Institut für Humangenetik, Universität des Saarlandes, Homburg, Germany.
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Bilaud T, Koering CE, Binet-Brasselet E, Ancelin K, Pollice A, Gasser SM, Gilson E. The telobox, a Myb-related telomeric DNA binding motif found in proteins from yeast, plants and human. Nucleic Acids Res 1996; 24:1294-303. [PMID: 8614633 PMCID: PMC145771 DOI: 10.1093/nar/24.7.1294] [Citation(s) in RCA: 178] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The yeast TTAGGG binding factor 1 (Tbf1) was identified and cloned through its ability to interact with vertebrate telomeric repeats in vitro. We show here that a sequence of 60 amino acids located in its C-terminus is critical for DNA binding. This sequence exhibits homologies with Myb repeats and is conserved among five proteins from plants, two of which are known to bind telomeric-related sequences, and two proteins from human, including the telomeric repeat binding factor (TRF) and the predicted C-terminal polypeptide, called orf2, from a yet unknown protein. We demonstrate that the 111 C-terminal residues of TRF and the 64 orf2 residues are able to bind the human telomeric repeats specifically. We propose to call the particular Myb-related motif found in these proteins the 'telobox'. Antibodies directed against the Tbf1 telobox detect two proteins in nuclear and mitotic chromosome extracts from human cell lines. Moreover, both proteins bind specifically to telomeric repeats in vitro. TRF is likely to correspond to one of them. Based on their high affinity for the telomeric repeat, we predict that TRF and orf2 play an important role at human telomeres.
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Affiliation(s)
- T Bilaud
- Laboratoire de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, France
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Lin HH, Sternfeld DC, Shinpock SG, Popp RA, Mucenski ML. Functional analysis of the c-myb proto-oncogene. Curr Top Microbiol Immunol 1996; 211:79-87. [PMID: 8585967 DOI: 10.1007/978-3-642-85232-9_8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Targeted mutagenesis studies were initiated to determine the normal biological function of the c-myb proto-oncogene. While heterozygous mice are phenotypically indistinguishable from their wild-type littermates, homozygous mutant fetuses die at approximately 15.5 days of gestation apparently due to anemia, which results from an inability to switch from embryonic yolk sac to fetal liver erythropoiesis. Studies are currently being done to determine the extent of hematopoietic abnormalities in the homozygous mutant fetuses. In vitro assays for hematopoietic colony-forming cells have been used to determine the frequency of both erythroid and myeloid progenitors in the fetal livers of wild-type, heterozygous, and homozygous mutant c-myb fetuses. The reduced number of erythroid progenitors was not unexpected considering the mutant fetus's pale color and reduced hematocrit. The dramatically reduced number of colonies derived from myeloid progenitors in the mutant fetuses in comparison to the number detected in phenotypically normal littermates suggests that expression of the c-myb proto-oncogene is critical for the proliferation and/or differentiation of early hematopoietic progenitors and possibly hematopoietic stem cells. Other possible explanations would include a hematopoietic progenitor migration problem from the yolk sac to the fetal liver or a defect in the microenvironment of the liver. Whether the lymphoid lineage is also adversely affected by the lack of c-myb expression remains to be determined. RT-PCR and Northern blot analyses were used in an attempt to identify downstream genes which may be directly or indirectly regulated by the Myb gene product. While the levels of expression of several genes involved in erythropoiesis (GATA-1, NF-E2, SCL, and EpoR) were reduced in the livers of homozygous mutant fetuses in comparison to phenotypically normal littermates and one gene, Kit ligand (KL), was expressed at higher levels in the mutant livers, these results must be viewed with caution. The livers of the mutant fetuses have been shown to be hypocellular in comparison to those of phenotypically normal littermates (35). It is possible that the Myb gene product is directly or indirectly modulating the expression of these genes. Conversely, the alteration in expression may be due to the reduced number or absence of specific hematopoietic lineages in the livers of the mutant fetuses. Differential display has also been used to identify putative novel genes that are involved in hematopoiesis. Preliminary studies suggest that this may be a powerful methodology to compare the expression pattern of genes in the fetal liver of wild-type, heterozygous, and homozygous mutant littermates at 14.5 days of gestation. To date nearly 60% of the partial cDNAs subcloned analyzed have been shown to be differentially expressed. More importantly, 75% of the differentially expressed cDNAs that have been sequenced appear to encode novel genes. Whether any of these novel genes are involved in the c-myb transcriptional cascade remains to be determined. Overall, analysis of the c-myb mutant fetuses have provided valuable insight into the biological function of this interesting proto-oncogene. The continued analysis of this resource will undoubtedly provide additional information concerning the role of the c-myb gene in hematopoiesis.
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Affiliation(s)
- H H Lin
- University of Tennessee Graduate School of Biomedical Sciences, Oak Ridge 37831-8080, USA
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Abstract
The earliest progenitor cell committed to the granulocyte/monocyte developmental pathway can be identified by the appearance of a 150-kDa glycoprotein on the cell surface (CD13/aminopeptidase N (CD13/APN), EC 3.4.11.2). A 455-base pair genomic fragment from the CD13/APN gene containing a Myb consensus-binding site as well as three potential Ets-binding sites was found to regulate tissue-appropriate expression of reporter genes in hematopoietic cell lines. Transactivation experiments with plasmids expressing either a full-length or truncated Myb protein and the full-length Ets-1 or Ets-2 protein demonstrated that these proteins cooperate to positively regulate CD13/APN gene expression. This cooperation is synergistic, as levels of transcriptional activity produced by Myb and Ets in combination were higher than those expected from a purely additive effect. Mutation of the Myb consensus-binding site completely abolished CD13/APN promoter activity in myeloid cells. Introduction of a dominant interfering Myb allele disrupted the ability of endogenous c-Myb in myeloid cells to transactivate the CD13/APN construct. Other myeloid cell-expressed Ets family members (PU.1, Fli-1, and Elf-1) failed to produce a cooperative transactivating effect when combined with the Myb expression construct. These data contrast with previous studies indicating that full-length c-Myb is unable to positively cooperate with Ets proteins in the regulation of myeloid genes. Because intact c-Myb and Ets-2 proteins, both endogenously expressed in myeloid cells, act synergistically to transactivate the CD13/APN promoter, this gene may represent a physiological target for dissection of the roles of these transcription factors in normal and malignant myelopoiesis.
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Affiliation(s)
- L H Shapiro
- Department of Experimental Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101, USA
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