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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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152
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Arratia-Quijada J, Sánchez O, Scazzocchio C, Aguirre J. FlbD, a Myb transcription factor of Aspergillus nidulans, is uniquely involved in both asexual and sexual differentiation. EUKARYOTIC CELL 2012; 11:1132-42. [PMID: 22798393 PMCID: PMC3445977 DOI: 10.1128/ec.00101-12] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 07/06/2012] [Indexed: 01/01/2023]
Abstract
In the fungus Aspergillus nidulans, inactivation of the flbA to -E, fluG, fluF, and tmpA genes results in similar phenotypes, characterized by a delay in conidiophore and asexual spore production. flbB to -D encode transcription factors needed for proper expression of the brlA gene, which is essential for asexual development. However, recent evidence indicates that FlbB and FlbE also have nontranscriptional functions. Here we show that fluF1 is an allele of flbD which results in an R47P substitution. Amino acids C46 and R47 are highly conserved in FlbD and many other Myb proteins, and C46 has been proposed to mediate redox regulation. Comparison of ΔflbD and flbD(R47P) mutants uncovered a new and specific role for flbD during sexual development. While flbD(R47P) mutants retain partial function during conidiation, both ΔflbD and flbD(R47P) mutants are unable to develop the peridium, a specialized external tissue that differentiates during fruiting body formation and ends up surrounding the sexual spores. This function, unique among other fluffy genes, does not affect the viability of the naked ascospores produced by mutant strains. Notably, ascospore development in these mutants is still dependent on the NADPH oxidase NoxA. We generated R47K, C46D, C46S, and C46A mutant alleles and evaluated their effects on asexual and sexual development. Conidiation defects were most severe in ΔflbD mutants and stronger in R47P, C46D, and C46S strains than in R47K strains. In contrast, mutants carrying the flbD(C46A) allele exhibited conidiation defects in liquid culture only under nitrogen starvation conditions. The R47K, R47P, C46D, and C46S mutants failed to develop any peridial tissue, while the flbD(C46A) strain showed normal peridium development and increased cleistothecium formation. Our results show that FlbD regulates both asexual and sexual differentiation, suggesting that both processes require FlbD DNA binding activity and that FlbD is involved in the response to nitrogen starvation.
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Affiliation(s)
- Jenny Arratia-Quijada
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Olivia Sánchez
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Claudio Scazzocchio
- Institut de Génétique et Microbiologie, Université Paris-Sud (XI), Orsay, France
- Department of Microbiology, Imperial College London, London, United Kingdom
| | - Jesús Aguirre
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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153
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Marino D, Peeters N, Rivas S. Ubiquitination during plant immune signaling. PLANT PHYSIOLOGY 2012; 160:15-27. [PMID: 22689893 PMCID: PMC3440193 DOI: 10.1104/pp.112.199281] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 06/09/2012] [Indexed: 05/18/2023]
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154
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Rovani MK, Brachmann CB, Ramsay G, Katzen AL. The dREAM/Myb-MuvB complex and Grim are key regulators of the programmed death of neural precursor cells at the Drosophila posterior wing margin. Dev Biol 2012; 372:88-102. [PMID: 22960039 DOI: 10.1016/j.ydbio.2012.08.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 07/23/2012] [Accepted: 08/14/2012] [Indexed: 10/27/2022]
Abstract
Successful development of a multicellular organism depends on the finely tuned orchestration of cell proliferation, differentiation and apoptosis from embryogenesis through adulthood. The MYB-gene family encodes sequence-specific DNA-binding transcription factors that have been implicated in the regulation of both normal and neoplastic growth. The Drosophila Myb protein, DMyb (and vertebrate B-Myb protein), has been shown to be part of the dREAM/MMB complex, a large multi-subunit complex, which in addition to four Myb-interacting proteins including Mip130, contains repressive E2F and pRB proteins. This complex has been implicated in the regulation of DNA replication within the context of chorion gene amplification and transcriptional regulation of a wide array of genes. Detailed phenotypic analysis of mutations in the Drosophila myb gene, Dm myb, has revealed a previously undiscovered function for the dREAM/MMB complex in regulating programmed cell death (PCD). In cooperation with the pro-apoptotic protein Grim and dREAM/MMB, DMyb promotes the PCD of specified sensory organ precursor daughter cells in at least two different settings in the peripheral nervous system: the pIIIb precursor of the neuron and sheath cells in the posterior wing margin and the glial cell in the thoracic microchaete lineage. Unlike previously analyzed settings, in which the main role of DMyb has been to antagonize the activities of other dREAM/MMB complex members, it appears to be the critical effector in promoting PCD. The finding that Dm myb and grim are both involved in regulating PCD in two distinct settings suggests that these two genes may often work together to mediate PCD.
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Affiliation(s)
- Margritte K Rovani
- Department of Biochemistry and Molecular Genetics University of Illinois at Chicago, 900 South Ashland Avenue, Chicago, IL 60607-7170, USA
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155
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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: 1.2] [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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156
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157
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Liu D, Shi M, Zhang H, Qian L, Yu M, Hu M, Zhang R, Wang T, Han C, Duan H, Guo N. c-Myb regulates cell cycle-dependent expression of Erbin: an implication for a novel function of Erbin. PLoS One 2012; 7:e42903. [PMID: 22880131 PMCID: PMC3413663 DOI: 10.1371/journal.pone.0042903] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 07/12/2012] [Indexed: 11/23/2022] Open
Abstract
In the present study, we demonstrated the cell cycle periodicity of Erbin expression with the maximal expression of Erbin in G2/M phase. A significant increase in Erbin promoter activity was observed in G2/M phase-synchronized cells. Sequence analysis revealed a c-Myb site in the core promoter region of Erbin. Mutagenesis of c-Myb consensus sequences abrogated the increased Erbin promoter activity in G2/M phase. ChIP and oligonucleotide pull-down assays validated that the recruitment of c-Myb to the consensus sequences was specific. The interaction of c-Myb with c-Myb site in the Erbin promoter was significantly enhanced in G2/M phase. Ectopic overexpression of c-Myb led to the up-regulation of Erbin promoter activity and c-Myb silencing by small interfering RNA significantly decreased Erbin protein level. Transfection of c-Myb rescued Erbin expression that was impaired by c-Myb knockdown. It proves that c-Myb and the c-Myb response element mediate the cell cycle-dependent expression of Erbin. Inactivation of Erbin causes an acceleration of the G1/S transition, the formation of multipolar spindles and abnormal chromosome congression. These results unravel a critical role of c-Myb in promoting Erbin transcription in G2/M phase and also predict an unappreciated function of Erbin in cell cycle progression.
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Affiliation(s)
- Dan Liu
- Department of Pathology, Hebei Medical University, Shijiazhuang, People's Republic of China
| | - Ming Shi
- Department of Pathophysiology, Institute of Basic Medical Sciences, Beijing, People's Republic of China
| | - Hao Zhang
- Department of Pathophysiology, Institute of Basic Medical Sciences, Beijing, People's Republic of China
| | - Lu Qian
- Department of Pathophysiology, Institute of Basic Medical Sciences, Beijing, People's Republic of China
| | - Ming Yu
- Department of Pathophysiology, Institute of Basic Medical Sciences, Beijing, People's Republic of China
| | - Meiru Hu
- Department of Pathophysiology, Institute of Basic Medical Sciences, Beijing, People's Republic of China
| | - Ruihong Zhang
- Department of Pathology, Hebei Medical University, Shijiazhuang, People's Republic of China
| | - Tianyou Wang
- Capital Institute of Pediatrics, Beijing, People's Republic of China
| | - Caili Han
- Department of Pathology, Hebei Medical University, Shijiazhuang, People's Republic of China
| | - Huijun Duan
- Department of Pathology, Hebei Medical University, Shijiazhuang, People's Republic of China
- * E-mail: (HD); (NG)
| | - Ning Guo
- Department of Pathophysiology, Institute of Basic Medical Sciences, Beijing, People's Republic of China
- * E-mail: (HD); (NG)
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158
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Ebata A, Suzuki T, Takagi K, Miki Y, Onodera Y, Nakamura Y, Fujishima F, Ishida K, Watanabe M, Tamaki K, Ishida T, Ohuchi N, Sasano H. Oestrogen-induced genes in ductal carcinoma in situ: their comparison with invasive ductal carcinoma. Endocr Relat Cancer 2012; 19:485-96. [PMID: 22569827 DOI: 10.1530/erc-11-0345] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
It is well known that oestrogens play important roles in both the pathogenesis and development of invasive ductal carcinoma (IDC) of human breast. However, molecular features of oestrogen actions have remained largely unclear in pure ductal carcinoma in situ (pDCIS), regarded as a precursor lesion of many IDCs. This is partly due to the fact that gene expression profiles of oestrogen-responsive genes have not been examined in pDCIS. Therefore, we first examined the profiles of oestrogen-induced genes in oestrogen receptor (ER)-positive pDCIS and DCIS (DCIS component (DCIS-c)) and IDC (IDC component (IDC-c)) components of IDC cases (n=4 respectively) by microarray analysis. Oestrogen-induced genes identified in this study were tentatively classified into three different groups in the hierarchical clustering analysis, and 33% of the genes were predominantly expressed in pDCIS rather than DCIS-c or IDC-c cases. Among these genes, the status of MYB (C-MYB), RBBP7 (RBAP46) and BIRC5 (survivin) expressions in carcinoma cells was significantly higher in ER-positive pDCIS (n=53) than that in ER-positive DCIS-c (n=27) or IDC-c (n=27) by subsequent immunohistochemical analysis of the corresponding genes (P<0.0001, P=0.03 and P=0.0003 respectively). In particular, the status of C-MYB immunoreactivity was inversely (P=0.006) correlated with Ki67 in the pDCIS cases. These results suggest that expression profiles of oestrogen-induced genes in pDCIS may be different from those in IDC; and C-MYB, RBAP46 and survivin may play important roles particularly among oestrogen-induced genes in ER-positive pDCIS.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/metabolism
- Carcinoma, Intraductal, Noninfiltrating/genetics
- Carcinoma, Intraductal, Noninfiltrating/metabolism
- Estrogens/pharmacology
- Female
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic/drug effects
- Genes, Neoplasm/drug effects
- Humans
- Microarray Analysis
- Middle Aged
- Up-Regulation/drug effects
- Up-Regulation/genetics
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Affiliation(s)
- Akiko Ebata
- Department of Pathology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aobaku, Sendai, Japan
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159
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Kurokawa K, Tanahashi T, Iima T, Yamamoto Y, Akaike Y, Nishida K, Masuda K, Kuwano Y, Murakami Y, Fukushima M, Rokutan K. Role of miR-19b and its target mRNAs in 5-fluorouracil resistance in colon cancer cells. J Gastroenterol 2012; 47:883-95. [PMID: 22382630 DOI: 10.1007/s00535-012-0547-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 01/04/2012] [Indexed: 02/04/2023]
Abstract
BACKGROUND Drug resistance in colorectal cancers is assumed to be mediated by changes in the expression of microRNAs, but the specific identities and roles of microRNAs are largely unclear. We examined the effect of 5-fluorouracil (5-FU) resistance on microRNA expression. METHODS Two types of 5-FU-resistant colon cancer cells were derived from the DLD-1 and KM12C cell lines. The expressions of microRNAs were profiled with a microarray containing 723 microRNAs and validated by quantitative real-time polymerase chain reaction (qRT-PCR). To survey the downstream mediators of microRNA, we used a microRNA:mRNA immunoprecipitation (RIP)-Chip and pathway analysis tool to identify potential direct targets of microRNA. RESULTS In response to 5-FU, miR-19b and miR-21 were over-expressed in 5-FU-resistant cells. Of note, miR-19b was up-regulated 3.47-fold in the DLD-1 resistant cells, which exhibited no alteration in cell cycle profiles despite exposure to 5-FU. After transfection of miR-19b, specific mRNAs were recruited to microRNA:mRNA complexes isolated with Ago2 antibody and subjected to whole-genome transcriptional analysis. In this analysis, 66 target mRNAs were enriched by at least 5.0-fold in the microRNA:mRNA complexes from DLD-1 resistant cells. Ingenuity pathway analysis of mRNA targets significantly (P < 0.05) indicated the category "Cell Cycle" as a probable area of the molecular and cellular function related with 5-FU resistance. Among candidate mRNA targets, SFPQ and MYBL2 have been linked to cell cycle functions. CONCLUSIONS We revealed up-regulation of miR-19b in response to 5-FU and potential targets of miR-19b mediating the cell cycle under treatment with 5-FU. Our study provides an important insight into the mechanism of 5-FU resistance in colorectal cancers.
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Affiliation(s)
- Ken Kurokawa
- Department of Stress Science, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, 770-8503, Japan
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160
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Distinct regulation of c-myb gene expression by HoxA9, Meis1 and Pbx proteins in normal hematopoietic progenitors and transformed myeloid cells. Blood Cancer J 2012; 2:e76. [PMID: 22829978 PMCID: PMC3389162 DOI: 10.1038/bcj.2012.20] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 05/03/2012] [Accepted: 05/07/2012] [Indexed: 12/11/2022] Open
Abstract
The proto-oncogenic protein c-Myb is an essential regulator of hematopoiesis and is frequently deregulated in hematological diseases such as lymphoma and leukemia. To gain insight into the mechanisms underlying the aberrant expression of c-Myb in myeloid leukemia, we analyzed and compared c-myb gene transcriptional regulation using two cell lines modeling normal hematopoietic progenitor cells (HPCs) and transformed myelomonocytic blasts. We report that the transcription factors HoxA9, Meis1, Pbx1 and Pbx2 bind in vivo to the c-myb locus and maintain its expression through different mechanisms in HPCs and leukemic cells. Our analysis also points to a critical role for Pbx2 in deregulating c-myb expression in murine myeloid cells cotransformed by the cooperative activity of HoxA9 and Meis1. This effect is associated with an intronic positioning of epigenetic marks and RNA polymerase II binding in the orthologous region of a previously described alternative promoter for c-myb. Taken together, our results could provide a first hint to explain the abnormal expression of c-myb in leukemic cells.
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161
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Lin Y, Son H, Min K, Lee J, Choi GJ, Kim JC, Lee YW. A putative transcription factor MYT2 regulates perithecium size in the ascomycete Gibberella zeae. PLoS One 2012; 7:e37859. [PMID: 22649560 PMCID: PMC3359310 DOI: 10.1371/journal.pone.0037859] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/25/2012] [Indexed: 11/18/2022] Open
Abstract
The homothallic ascomycete fungus Gibberella zeae is a plant pathogen that is found worldwide, causing Fusarium head blight (FHB) in cereal crops and ear rot of maize. Ascospores formed in fruiting bodies (i.e., perithecia) are hypothesized to be the primary inocula for FHB disease. Perithecium development is a complex cellular differentiation process controlled by many developmentally regulated genes. In this study, we selected a previously reported putative transcription factor containing the Myb DNA-binding domain MYT2 for an in-depth study on sexual development. The deletion of MYT2 resulted in a larger perithecium, while its overexpression resulted in a smaller perithecium when compared to the wild-type strain. These data suggest that MYT2 regulates perithecium size differentiation. MYT2 overexpression affected pleiotropic phenotypes including vegetative growth, conidia production, virulence, and mycotoxin production. Nuclear localization of the MYT2 protein supports its role as a transcriptional regulator. Transcriptional analyses of trichothecene synthetic genes suggest that MYT2 additionally functions as a suppressor for trichothecene production. This is the first study characterizing a transcription factor required for perithecium size differentiation in G. zeae, and it provides a novel angle for understanding sexual development in filamentous fungi.
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Affiliation(s)
- Yang Lin
- Department of Agricultural Biotechnology and the Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea
| | - Hokyoung Son
- Department of Agricultural Biotechnology and the Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea
| | - Kyunghun Min
- Department of Agricultural Biotechnology and the Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea
| | - Jungkwan Lee
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | - Gyung Ja Choi
- Eco-friendly New Materials Research Group, Research Center for Biobased Chemistry, Division of Convergence Chemistry, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
| | - Jin-Cheol Kim
- Eco-friendly New Materials Research Group, Research Center for Biobased Chemistry, Division of Convergence Chemistry, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
| | - Yin-Won Lee
- Department of Agricultural Biotechnology and the Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea
- * E-mail:
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162
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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: 0.8] [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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163
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Cho CC, Su LH, Huang YC, Pan YJ, Sun CH. Regulation of a Myb transcription factor by cyclin-dependent kinase 2 in Giardia lamblia. J Biol Chem 2011; 287:3733-50. [PMID: 22167200 DOI: 10.1074/jbc.m111.298893] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protozoan Giardia lamblia parasitizes the human small intestine to cause diseases. It undergoes differentiation into infectious cysts by responding to intestinal stimulation. How the activated signal transduction pathways relate to encystation stimulation remain largely unknown. During encystation, genes encoding cyst wall proteins (CWPs) are coordinately up-regulated by a Myb2 transcription factor. Because cell differentiation is linked to cell cycle regulation, we tried to understand the role of cell cycle regulators, cyclin-dependent kinases (Cdks), in encystation. We found that the recombinant Myb2 was phosphorylated by Cdk-associated complexes and the levels of phosphorylation increased significantly during encystation. We have identified a putative cdk gene (cdk2) by searching the Giardia genome database. Cdk2 was found to localize in the cytoplasm with higher expression during encystation. Interestingly, overexpression of Cdk2 resulted in a significant increase of the levels of cwp gene expression and cyst formation. In addition, the Cdk2-associated complexes can phosphorylate Myb2 and the levels of phosphorylation increased significantly during encystation. Mutations of important catalytic residues of Cdk2 resulted in a significant decrease of kinase activity and ability of inducing cyst formation. Addition of a Cdk inhibitor, purvalanol A, significantly decreased the Cdk2 kinase activity and the levels of cwp gene expression and cyst formation. Our results suggest that the Cdk2 pathway may be involved in phosphorylation of Myb2, leading to activation of the Myb2 function and up-regulation of cwp genes during encystation. The results provide insights into the use of Cdk inhibitory drugs in disruption of Giardia differentiation into cysts.
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Affiliation(s)
- Chao-Cheng Cho
- Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, Republic of China
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164
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Dynamic long-range chromatin interactions control Myb proto-oncogene transcription during erythroid development. EMBO J 2011; 31:986-99. [PMID: 22157820 PMCID: PMC3280550 DOI: 10.1038/emboj.2011.450] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 11/16/2011] [Indexed: 12/31/2022] Open
Abstract
The key haematopoietic regulator Myb is essential for coordinating proliferation and differentiation. ChIP-Sequencing and Chromosome Conformation Capture (3C)-Sequencing were used to characterize the structural and protein-binding dynamics of the Myb locus during erythroid differentiation. In proliferating cells expressing Myb, enhancers within the Myb-Hbs1l intergenic region were shown to form an active chromatin hub (ACH) containing the Myb promoter and first intron. This first intron was found to harbour the transition site from transcription initiation to elongation, which takes place around a conserved CTCF site. Upon erythroid differentiation, Myb expression is downregulated and the ACH destabilized. We propose a model for Myb activation by distal enhancers dynamically bound by KLF1 and the GATA1/TAL1/LDB1 complex, which primarily function as a transcription elongation element through chromatin looping.
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165
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Identification of genes involved in the regulation of 14-deoxy-11,12-didehydroandrographolide-induced toxicity in T-47D mammary cells. Food Chem Toxicol 2011; 50:431-44. [PMID: 22101062 DOI: 10.1016/j.fct.2011.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 09/30/2011] [Accepted: 11/03/2011] [Indexed: 12/19/2022]
Abstract
14-Deoxy-11,12-didehydroandrographolide is one of the principle compounds of the medicinal plant, Andrographis paniculata Nees. This study explored the mechanisms of 14-deoxy-11,12-didehydroandrographolide-induced toxicity and non-apoptotic cell death in T-47D breast carcinoma cells. Gene expression analysis revealed that 14-deoxy-11,12-didehydroandrographolide exerted its cytotoxic effects by regulating genes that inhibit the cell cycle or promote cell cycle arrest. This compound regulated genes that are known to reduce/inhibit cell proliferation, induce growth arrest and suppress cell growth. The growth suppression activities of this compound were demonstrated by a downregulation of several genes normally found to be over-expressed in cancers. Microscopic analysis revealed positive monodansylcadaverine (MDC) staining at 8h, indicating possible autophagosomes. TEM analysis revealed that the treated cells were highly vacuolated, thereby suggesting that 14-deoxy-11,12-didehydroandrographolide may cause autophagic morphology in these cells. This morphology may be correlated with the concurrent expression of genes known to affect lysosomal activity, ion transport, protein degradation and vesicle transport. Interestingly, some apoptotic-like bodies were found, and these bodies contained multiple large vacuoles, suggesting that this compound is capable of eliciting a combination of apoptotic and autophagic-like morphological characteristics.
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166
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Li SD, Tagami T, Ho YF, Yeang CH. Deciphering causal and statistical relations of molecular aberrations and gene expressions in NCI-60 cell lines. BMC SYSTEMS BIOLOGY 2011; 5:186. [PMID: 22051105 PMCID: PMC3259106 DOI: 10.1186/1752-0509-5-186] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 11/04/2011] [Indexed: 12/02/2022]
Abstract
BACKGROUND Cancer cells harbor a large number of molecular alterations such as mutations, amplifications and deletions on DNA sequences and epigenetic changes on DNA methylations. These aberrations may dysregulate gene expressions, which in turn drive the malignancy of tumors. Deciphering the causal and statistical relations of molecular aberrations and gene expressions is critical for understanding the molecular mechanisms of clinical phenotypes. RESULTS In this work, we proposed a computational method to reconstruct association modules containing driver aberrations, passenger mRNA or microRNA expressions, and putative regulators that mediate the effects from drivers to passengers. By applying the module-finding algorithm to the integrated datasets of NCI-60 cancer cell lines, we found that gene expressions were driven by diverse molecular aberrations including chromosomal segments' copy number variations, gene mutations and DNA methylations, microRNA expressions, and the expressions of transcription factors. In-silico validation indicated that passenger genes were enriched with the regulator binding motifs, functional categories or pathways where the drivers were involved, and co-citations with the driver/regulator genes. Moreover, 6 of 11 predicted MYB targets were down-regulated in an MYB-siRNA treated leukemia cell line. In addition, microRNA expressions were driven by distinct mechanisms from mRNA expressions. CONCLUSIONS The results provide rich mechanistic information regarding molecular aberrations and gene expressions in cancer genomes. This kind of integrative analysis will become an important tool for the diagnosis and treatment of cancer in the era of personalized medicine.
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Affiliation(s)
- Shyh-Dar Li
- Ontario Institute for Cancer Research, 101 College Street, Toronto, Canada
| | | | - Ying-Fu Ho
- Institute of Statistical Science, Academia Sinica, Academia Road, Sec 2, Taipei, Taiwan
| | - Chen-Hsiang Yeang
- Institute of Statistical Science, Academia Sinica, Academia Road, Sec 2, Taipei, Taiwan
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167
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Kozuka T, Sugita M, Shetzline S, Gewirtz AM, Nakata Y. c-Myb and GATA-3 cooperatively regulate IL-13 expression via conserved GATA-3 response element and recruit mixed lineage leukemia (MLL) for histone modification of the IL-13 locus. THE JOURNAL OF IMMUNOLOGY 2011; 187:5974-82. [PMID: 22039304 DOI: 10.4049/jimmunol.1100550] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The c-Myb and GATA-3 transcription factors play important roles in T cell development. We recently reported that c-Myb, GATA-3, and Menin form a core transcription complex that regulates GATA-3 expression and ultimately Th2 cell development in human peripheral blood T cells. However, c-Myb roles for Th2 cytokine expression were not demonstrated. In this article, we report that c-Myb and GATA-3 cooperatively play an essential role in IL-13 expression though direct binding to a conserved GATA-3 response element (CGRE), an enhancer for IL-13 expression. c-Myb and GATA-3 were shown to activate the CGRE-IL-13 promoter by ∼160-fold, and mutation of the canonical Myb binding site completely abrogated CGRE enhancer activity. In contrast, mutation of the GATA binding site partially decreased CGRE enhancer activity. GATA-3 did not bind to CGRE when c-myb expression was silenced. c-Myb, GATA-3, Menin, and mixed lineage leukemia (MLL) bound to CGRE in human primary CD4(+) effector/memory cells. Moreover, c-myb silencing significantly decreased both methylation of histone H3K4 and acetylation of histone H3K9 at the IL-13 locus in CD4(+) effector/memory cells. Therefore, in addition to the strong enhancer effect for the transcription of IL-13, the c-Myb/GATA-3 complex recruits MLL to the CGRE for histone modification of the IL-13 locus during the differentiation of memory Th2 cells.
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Affiliation(s)
- Teruhiko Kozuka
- Division of Hematology/Oncology, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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168
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Lin Y, Son H, Lee J, Min K, Choi GJ, Kim JC, Lee YW. A putative transcription factor MYT1 is required for female fertility in the ascomycete Gibberella zeae. PLoS One 2011; 6:e25586. [PMID: 21984921 PMCID: PMC3184970 DOI: 10.1371/journal.pone.0025586] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 09/06/2011] [Indexed: 11/19/2022] Open
Abstract
Gibberella zeae is an important pathogen of major cereal crops. The fungus produces ascospores that forcibly discharge from mature fruiting bodies, which serve as the primary inocula for disease epidemics. In this study, we characterized an insertional mutant Z39P105 with a defect in sexual development and identified a gene encoding a putative transcription factor designated as MYT1. This gene contains a Myb DNA-binding domain and is conserved in the subphylum Pezizomycotina of Ascomycota. The MYT1 protein fused with green fluorescence protein localized in nuclei, which supports its role as a transcriptional regulator. The MYT1 deletion mutant showed similar phenotypes to the wild-type strain in vegetative growth, conidia production and germination, virulence, and mycotoxin production, but had defect in female fertility. A mutant overexpressing MYT1 showed earlier germination, faster mycelia growth, and reduced mycotoxin production compared to the wild-type strain, suggesting that improper MYT1 expression affects the expression of genes involved in the cell cycle and secondary metabolite production. This study is the first to characterize a transcription factor containing a Myb DNA-binding domain that is specific to sexual development in G. zeae.
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Affiliation(s)
- Yang Lin
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, Seoul, Korea
| | - Hokyoung Son
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, Seoul, Korea
| | - Jungkwan Lee
- Department of Applied Biology, Dong-A University, Busan, Korea
| | - Kyunghun Min
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, Seoul, Korea
| | - Gyung Ja Choi
- Biological Function Research Team, Korea Research Institute of Chemical Technology, Daejeon, Korea
| | - Jin-Cheol Kim
- Biological Function Research Team, Korea Research Institute of Chemical Technology, Daejeon, Korea
| | - Yin-Won Lee
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, Seoul, Korea
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169
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Bolcun-Filas E, Bannister LA, Barash A, Schimenti KJ, Hartford SA, Eppig JJ, Handel MA, Shen L, Schimenti JC. A-MYB (MYBL1) transcription factor is a master regulator of male meiosis. Development 2011; 138:3319-30. [PMID: 21750041 DOI: 10.1242/dev.067645] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The transcriptional regulation of mammalian meiosis is poorly characterized, owing to few genetic and ex vivo models. From a genetic screen, we identify the transcription factor MYBL1 as a male-specific master regulator of several crucial meiotic processes. Spermatocytes bearing a novel separation-of-function allele (Mybl1(repro9)) had subtle defects in autosome synapsis in pachynema, a high incidence of unsynapsed sex chromosomes, incomplete double-strand break repair on synapsed pachytene chromosomes and a lack of crossing over. MYBL1 protein appears in pachynema, and its mutation caused specific alterations in expression of diverse genes, including some translated postmeiotically. These data, coupled with chromatin immunoprecipitation (ChIP-chip) experiments and bioinformatic analysis of promoters, identified direct targets of MYBL1 regulation. The results reveal that MYBL1 is a master regulator of meiotic genes that are involved in multiple processes in spermatocytes, particularly those required for cell cycle progression through pachynema.
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Affiliation(s)
- Ewelina Bolcun-Filas
- Cornell University College of Veterinary Medicine, Department of Biomedical Sciences, Center for Vertebrate Genomics, Ithaca, NY 14850, USA
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170
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Analysis of MYB expression and MYB-NFIB gene fusions in adenoid cystic carcinoma and other salivary neoplasms. Mod Pathol 2011; 24:1169-76. [PMID: 21572406 DOI: 10.1038/modpathol.2011.86] [Citation(s) in RCA: 259] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Recent studies have shown that the recurrent t(6;9)(q22-23;p23-24) translocation in adenoid cystic carcinoma results in a novel fusion of the MYB proto-oncogene with the transcription factor gene NFIB. To determine the frequency of this finding, we used RT-PCR assays of the MYB and MYB-NFIB fusion transcripts, and immunohistochemistry for the MYB protein, to study adenoid cystic carcinomas and other epithelial tumors of the salivary glands, and head and neck region. MYB-NFIB fusion transcript was detected in 25 of 29 (86%) frozen adenoid cystic carcinoma tumor samples, and in 14 of 32 (44%) formalin-fixed paraffin-embedded adenoid cystic carcinoma tumor specimens. In contrast, the MYB-NFIB fusion was not expressed in non-adenoid cystic carcinoma neoplasms of the head and neck, confirming the high specificity of the MYB-NFIB fusion. Adenoid cystic carcinomas from various anatomic sites, including salivary gland, sinonasal cavity, tracheobronchial tree, larynx, breast, and vulva were repeatedly fusion-positive, indicating that adenoid cystic carcinomas located in different anatomic sites not only have important morphologic features in common, but also probably evolve through activation of the same molecular pathways. Studies of the expression of MYB revealed that 89% of the tumors, including both fusion-positive and fusion-negative cases, overexpressed MYB RNA. Similarly, 82% of adenoid cystic carcinomas stained positive for MYB protein, compared with 14% of non-adenoid cystic carcinoma neoplasms, indicating that MYB immunostaining may be useful for the diagnosis of adenoid cystic carcinoma, but that neoplasms sometimes in the differential diagnosis are also labeled. The latter are, however, fusion-negative. In summary, our studies show that MYB activation through gene fusion or other mechanisms is a major oncogenic event in adenoid cystic carcinoma occurring at various anatomic sites. In addition to being a diagnostically useful biomarker for adenoid cystic carcinoma, MYB and its downstream effectors are also novel potential therapeutic targets.
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171
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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: 0.4] [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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172
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Ross AL, Leder DE, Weiss J, Izakovic J, Grichnik JM. Genomic instability in cultured stem cells: associated risks and underlying mechanisms. Regen Med 2011; 6:653-62. [DOI: 10.2217/rme.11.44] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Embryonic stem cells, mesenchymal stem cells and induced pluripotent stem cells expanded in vitro exhibit genomic instability. Commonly reported abnormalities include aneuploidy, deletions and duplications (including regions also amplified in cancer). Genomic instability confers an increased risk of malignant transformation that may impact the safety of cultured stem cell transplantation. Possible mechanisms responsible for this genomic instability include DNA repair mechanism abnormalities, telomere crisis, mitotic spindle abnormalities and inappropriate induction of meiotic pathways. Prior to widespread use of these cells in regenerative medicine, it will be critical to gain an understanding of the mechanisms responsible for genomic instability to develop strategies to prevent the accrual of chromosomal defects during expansion in vitro.
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Affiliation(s)
- Andrew L Ross
- Interdisciplinary Stem Cell Institute, University of Miami, Miller School of Medicine, Miami FL 33136, USA; Department of Dermatology, Melanoma Program Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Room 912, BRB, 1501 NW 10th Ave, Miami, FL 33136, USA
- Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Daniel E Leder
- Interdisciplinary Stem Cell Institute, University of Miami, Miller School of Medicine, Miami FL 33136, USA; Department of Dermatology, Melanoma Program Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Room 912, BRB, 1501 NW 10th Ave, Miami, FL 33136, USA
- Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Jonathan Weiss
- Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Jan Izakovic
- Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - James M Grichnik
- Interdisciplinary Stem Cell Institute, University of Miami, Miller School of Medicine, Miami FL 33136, USA; Department of Dermatology, Melanoma Program Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Room 912, BRB, 1501 NW 10th Ave, Miami, FL 33136, USA
- Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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173
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Abstract
The transcription factor B-Myb plays a critical role in regulating gene expression and is implicated in controlling carcinogenesis and cellular senescence. Transcription of the B-Myb gene is regulated by retinoblastoma proteins acting directly on the B-Myb promoter. Recently, we found that microRNAs also control the abundance of B-Myb mRNA during senescence, adding another level of complexity to B-Myb regulation. This review focuses on the importance of B-Myb in cancer and senescence, with an emphasis on the regulation of B-Myb expression and activity.
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Affiliation(s)
- Ivan Martinez
- Department of Genetics and Yale Comprehensive Cancer Center, Yale School of Medicine, New Haven, Connecticut 06520-8005, USA
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174
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Zhou F, Zhang L, van Laar T, van Dam H, Ten Dijke P. GSK3β inactivation induces apoptosis of leukemia cells by repressing the function of c-Myb. Mol Biol Cell 2011; 22:3533-40. [PMID: 21795403 PMCID: PMC3172276 DOI: 10.1091/mbc.e11-06-0483] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The level of c-Myb is a determining factor in the response of leukemia cells to GSK3β kinase inhibiton, which is of particular interest for the therapy of leukemia and cancers that have c-Myb amplifications. Glycogen synthase kinase 3β (GSK3β) regulates diverse physiological processes, including metabolism, development, oncogenesis, and neuroprotection. GSK3β kinase activity has been reported to be critical for various types of cancer cells, but the mechanism has remained elusive. In this study we examine the mechanism by which GSK3β regulates the survival of leukemia cells. We demonstrate that upon GSK3β kinase inhibition different types of leukemia cells show severe proliferation defects as a result of apoptosis. The transcription factor c-Myb is found to be the main target of GSK3β inhibition in cell survival. GSK3β inactivation reduces the expression of c-Myb by promoting its ubiquitination-mediated degradation, thereby inhibiting the expression of c-Myb–dependent antiapoptotic genes Bcl2 and survivin. Coimmunoprecipitation, reporter assays, chromatin immunoprecipitation, and knockdown studies show that c-Myb needs to interact and cooperate with transcription factor LEF-1 in the activation of Bcl2 and survivin and that both transcription factors are required for cell survival. These data reveal an as-yet-unknown mechanism by which GSK3β controls cell survival.
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Affiliation(s)
- Fangfang Zhou
- Department of Molecular Cell Biology and Centre for Biomedical Genetics, Leiden University Medical Center, 2300 RC Leiden, Netherlands
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175
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Matalová E, Buchtová M, Tucker AS, Bender TP, Janečková E, Lungová V, Balková S, Smarda J. Expression and characterization of c-Myb in prenatal odontogenesis. Dev Growth Differ 2011; 53:793-803. [PMID: 21762405 DOI: 10.1111/j.1440-169x.2011.01287.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transcription factor c-Myb is involved in the control of cell proliferation, survival and differentiation. As these processes accompany the morphogenesis of developing teeth, this work investigates the possible role of c-Myb during odontogenesis. Analysis of the expression of c-Myb in the monophyodont mouse was followed by similar analysis in a diphyodont species, the pig, which has a dentition more closely resembling that of the human. The distribution of c-Myb was correlated with the pattern of proliferation and apoptosis and the tooth phenotype of c-Myb mutant mice was also assessed. In the mouse, c-Myb expression was detected throughout prenatal development of the first molar tooth. Negative temporospatial correlation was found between c-Myb expression and apoptosis, while c-Myb expression positively correlated with proliferation. c-Myb-positive cells, however, were more abundant than the proliferating cell nuclear antigen positive cells, suggesting other roles of c-Myb in odontogenesis. In the minipig, in contrast to the mouse, there was an asymmetrical arrangement of c-Myb positive cells, with a higher presence on the labial side of the tooth germ and dental lamina. A cluster of negative cells was situated in the mesenchyme close to the tooth bud. At later stages, the number of positive cells decreased and these cells were situated in the upper part of the dental papilla in the areas of future cusp formation. The expression of c-Myb in both species was strong in the odontoblasts and ameloblasts at the stage of dentin and enamel production suggesting a possible novel role of c-Myb during tooth mineralization.
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Affiliation(s)
- Eva Matalová
- Institute of Animal Physiology and Genetics, v.v.i., Academy of Sciences of the Czech Republic.
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176
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Shen Z, Chen L, Hao F, Wang G, Liu Y. Intron-1 rs3761548 is related to the defective transcription of Foxp3 in psoriasis through abrogating E47/c-Myb binding. J Cell Mol Med 2011. [PMID: 20414968 DOI: 10.1111/j.1582-4934.2008.00370.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Foxp3 is a master transcription factor (TF) for development and function of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg cells) and is critical for the transcription of target genes. But the transcriptional regulation of Foxp3 itself has not been fully understood until now. Here, we aimed to demonstrate the hypothesis that upstream single nucleotide polymorphism(s) (SNPs) of Foxp3 was/were responsible for the defective transcription of Foxp3 in psoriasis and to explore the mechanism behind this hypothesis. In this study, SNP of large sample was investigated for risk analysis. Mature algorithms, electrophoretic mobility shift and chromatin immunoprecipitation assays were used to identify TF binding site variations. Loss-of-function and overexpression assays and cell cycle blocker assay were performed to identify when and what kind of possible roles the candidate factors play. Our results showed that intron-1 rs3761548 was correlated with a significant susceptibility to psoriasis. The rs3761548 contributed to the decreased resting Foxp3 transcription and impaired acceleration of Foxp3 transcription levels after stimulation in psoriatic patients with genotype AA. We analysed and demonstrated potent new E47/c-Myb -dependent regulation elements in rs3761548, oppositely controlling Foxp3 gene transcription at G1 and G2/M phases of Treg cells in psoriatic patients. For patients with rs3761548 AA, the polymorphism causes loss of bindings to the E47 and c-Myb factors, leading to defective transcription of Foxp3 gene. Further identification of the networks and molecular mechanisms underlying Foxp3 transcription may provide new insights into Foxp3 transcriptional regulation and alternative therapeutic strategies to improve characteristics of autoimmune disorders.
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Affiliation(s)
- Z Shen
- Department of Dermatology, Southwest Hospital, Third Military Medical University, Chongqing, China.
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177
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Fehr A, Kovács A, Löning T, Frierson H, van den Oord J, Stenman G. The MYB-NFIB gene fusion-a novel genetic link between adenoid cystic carcinoma and dermal cylindroma. J Pathol 2011; 224:322-7. [PMID: 21618541 DOI: 10.1002/path.2909] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 03/24/2011] [Accepted: 03/26/2011] [Indexed: 01/09/2023]
Abstract
We have recently shown that the recurrent t(6;9)(q22 ∼ 23;p23 ∼ 24) translocation in adenoid cystic carcinoma (ACC) of the breast and head and neck results in a fusion of the two transcription factor genes MYB and NFIB. Here we demonstrate, for the first time, that benign sporadic, dermal cylindromas also express the MYB-NFIB gene fusion. RT-PCR and immunohistochemical analyses revealed that eight of 12 analysed tumours (67%) expressed MYB-NFIB fusion transcripts and/or stained positive for MYB protein. Nucleotide sequence analyses confirmed that the composition of the chimeric transcript variants identified was identical to that in ACC, suggesting a similar molecular mechanism of activation of MYB in cylindroma as in ACC. In contrast, no evidence for the presence of the MYB-NFIB fusion was found in other types of basaloid skin and salivary gland tumours, indicating that the fusion indeed has a restricted expression pattern. Our findings broaden the spectrum of neoplasms associated with MYB oncogene activation and reveal a novel genetic link between ACC and dermal cylindroma. These results, together with our previous observations, further strengthen the evidence for common molecular pathways of importance for the development of both benign and malignant breast, salivary and adnexal tumours.
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Affiliation(s)
- A Fehr
- Sahlgrenska Cancer Center, Department of Pathology, Sahlgrenska Academy at University of Gothenburg, Sweden
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178
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Gambone JE, Dusaban SS, Loperena R, Nakata Y, Shetzline SE. The c-Myb target gene neuromedin U functions as a novel cofactor during the early stages of erythropoiesis. Blood 2011; 117:5733-43. [PMID: 21378276 PMCID: PMC3110030 DOI: 10.1182/blood-2009-09-242131] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 02/02/2011] [Indexed: 11/20/2022] Open
Abstract
The requirement of c-Myb during erythropoiesis spurred an interest in identifying c-Myb target genes that are important for erythroid development. Here, we determined that the neuropeptide neuromedin U (NmU) is a c-Myb target gene. Silencing NmU, c-myb, or NmU's cognate receptor NMUR1 expression in human CD34(+) cells impaired burst-forming unit-erythroid (BFU-E) and colony-forming unit-erythroid (CFU-E) formation compared with control. Exogenous addition of NmU peptide to NmU or c-myb siRNA-treated CD34(+) cells rescued BFU-E and yielded a greater number of CFU-E than observed with control. No rescue of BFU-E and CFU-E growth was observed when NmU peptide was exogenously added to NMUR1 siRNA-treated cells compared with NMUR1 siRNA-treated cells cultured without NmU peptide. In K562 and CD34(+) cells, NmU activated protein kinase C-βII, a factor associated with hematopoietic differentiation-proliferation. CD34(+) cells cultured under erythroid-inducing conditions, with NmU peptide and erythropoietin added at day 6, revealed an increase in endogenous NmU and c-myb gene expression at day 8 and a 16% expansion of early erythroblasts at day 10 compared to cultures without NmU peptide. Combined, these data strongly support that the c-Myb target gene NmU functions as a novel cofactor for erythropoiesis and expands early erythroblasts.
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Affiliation(s)
- Julia E Gambone
- Division of Hematology/Oncology, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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179
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Bian Z, Li L, Cui J, Zhang H, Liu Y, Zhang CY, Zen K. Role of miR-150-targeting c-Myb in colonic epithelial disruption during dextran sulphate sodium-induced murine experimental colitis and human ulcerative colitis. J Pathol 2011; 225:544-53. [PMID: 21590770 DOI: 10.1002/path.2907] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 01/12/2011] [Accepted: 01/30/2011] [Indexed: 12/11/2022]
Abstract
Chronic inflammatory bowel diseases (IBDs) are associated with differential expression of genes involved in inflammation and tissue remodelling. We surveyed the expression profile of apoptosis-related microRNAs by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) in a dextran sulphate sodium (DSS) murine model of colitis. We found that miR-150 was strongly elevated, whereas c-Myb, a transcription factor and a target gene of miR-150, was significantly reduced in colon tissue after DSS treatment. Interestingly, elevation of miR-150 and down-regulation of c-Myb were also observed in human colon with active ulcerative colitis compared to the normal colon. Supporting the observation of DSS treatment inducing colonic cell apoptosis, Bcl-2, an anti-apoptotic protein known to be regulated by c-Myb, was reduced in colon tissue of DSS-treated mice. Furthermore, forced expression of pre-miR-150 in colonic epithelial HT29 cells strongly elevated miR-150 levels and decreased c-Myb and Bcl-2 levels, thus enhancing cell apoptosis induced by serum deprivation. Together, the present study presents the first evidence that miR-150 and its targeting of c-Myb may serve as a new mechanism underlying the colonic epithelial disruption in DSS-induced murine experimental colitis and in active human IBD.
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Affiliation(s)
- Zhen Bian
- Jiangsu Engineering Research Center for microRNA Biology and Biotechnology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, 22 Hankou Road, Nanjing 210093, China
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180
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Morris AC, Forbes-Osborne MA, Pillai LS, Fadool JM. Microarray analysis of XOPS-mCFP zebrafish retina identifies genes associated with rod photoreceptor degeneration and regeneration. Invest Ophthalmol Vis Sci 2011; 52:2255-66. [PMID: 21217106 DOI: 10.1167/iovs.10-6022] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
PURPOSE XOPS-mCFP transgenic zebrafish experience a continual cycle of rod photoreceptor development and degeneration throughout life, making them a useful model for investigating the molecular determinants of rod photoreceptor regeneration. The purpose of this study was to compare the gene expression profiles of wild-type and XOPS-mCFP retinas and identify genes that may contribute to the regeneration of the rods. METHODS Adult wild-type and XOPS-mCFP retinal mRNA was subjected to microarray analysis. Pathway analysis was used to identify biologically relevant processes that were significantly represented in the dataset. Expression changes were verified by RT-PCR. Selected genes were further examined during retinal development and in adult retinas by in situ hybridization and immunohistochemistry and in a transgenic fluorescent reporter line. RESULTS More than 600 genes displayed significant expression changes in XOPS-mCFP retinas compared with expression in wild-type controls. Many of the downregulated genes were associated with phototransduction, whereas upregulated genes were associated with several biological functions, including cell cycle, DNA replication and repair, and cell development and death. RT-PCR analysis of a subset of these genes confirmed the microarray RESULTS Three transcription factors (sox11b, insm1a, and c-myb), displaying increased expression in XOPS-mCFP retinas, were also expressed throughout retinal development and in the persistently neurogenic ciliary marginal zone. CONCLUSIONS This study identified numerous gene expression changes in response to rod degeneration in zebrafish and further suggests a role for the transcriptional regulators sox11b, insm1a, and c-myb in both retinal development and rod photoreceptor regeneration.
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Affiliation(s)
- Ann C Morris
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA.
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Alm-Kristiansen AH, Lorenzo PI, Molværsmyr AK, Matre V, Ledsaak M, Sæther T, Gabrielsen OS. PIAS1 interacts with FLASH and enhances its co-activation of c-Myb. Mol Cancer 2011; 10:21. [PMID: 21338522 PMCID: PMC3050860 DOI: 10.1186/1476-4598-10-21] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Accepted: 02/21/2011] [Indexed: 11/15/2022] Open
Abstract
Background FLASH is a huge nuclear protein involved in various cellular functions such as apoptosis signalling, NF-κB activation, S-phase regulation, processing of histone pre-mRNAs, and co-regulation of transcription. Recently, we identified FLASH as a co-activator of the transcription factor c-Myb and found FLASH to be tightly associated with active transcription foci. As a huge multifunctional protein, FLASH is expected to have many interaction partners, some which may shed light on its function as a transcriptional regulator. Results To find additional FLASH-associated proteins, we performed a yeast two-hybrid (Y2H) screening with FLASH as bait and identified the SUMO E3 ligase PIAS1 as an interaction partner. The association appears to involve two distinct interaction surfaces in FLASH. We verified the interaction by Y2H-mating, GST pulldowns, co-IP and ChIP. FLASH and PIAS1 were found to co-localize in nuclear speckles. Functional assays revealed that PIAS1 enhances the intrinsic transcriptional activity of FLASH in a RING finger-dependent manner. Furthermore, PIAS1 also augments the specific activity of c-Myb, and cooperates with FLASH to further co-activate c-Myb. The three proteins, FLASH, PIAS1, and c-Myb, are all co-localized with active RNA polymerase II foci, resembling transcription factories. Conclusions We conclude that PIAS1 is a common partner for two cancer-related nuclear factors, c-Myb and FLASH. Our results point to a functional cooperation between FLASH and PIAS1 in the enhancement of c-Myb activity in active nuclear foci.
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Bhaijee F, Pepper DJ, Pitman KT, Bell D. New developments in the molecular pathogenesis of head and neck tumors: a review of tumor-specific fusion oncogenes in mucoepidermoid carcinoma, adenoid cystic carcinoma, and NUT midline carcinoma. Ann Diagn Pathol 2011; 15:69-77. [DOI: 10.1016/j.anndiagpath.2010.12.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2010] [Accepted: 12/02/2010] [Indexed: 12/27/2022]
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Novel core promoter elements and a cognate transcription factor in the divergent unicellular eukaryote Trichomonas vaginalis. Mol Cell Biol 2011; 31:1444-58. [PMID: 21245378 DOI: 10.1128/mcb.00745-10] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A highly conserved DNA initiator (Inr) element has been the only core promoter element described in the divergent unicellular eukaryote Trichomonas vaginalis, although genome analyses reveal that only ∼75% of protein-coding genes appear to contain an Inr. In search of another core promoter element(s), a nonredundant database containing 5' untranslated regions of expressed T. vaginalis genes was searched for overrepresented DNA motifs and known eukaryotic core promoter elements. In addition to identifying the Inr, two elements that lack sequence similarity to the known protein-coding gene core promoter, motif 3 (M3) and motif 5 (M5), were identified. Mutational and functional analyses demonstrate that both are novel core promoter elements. M3 [(A/G/T)(A/G)C(G/C)G(T/C)T(T/A/G)] resembles a Myb recognition element (MRE) and is bound specifically by a unique protein with a Myb-like DNA binding domain. The M5 element (CCTTT) overlaps the transcription start site and replaces the Inr as an alternative, gene-specific initiator element. Transcription specifically initiates at the second cytosine within M5, in contrast to characteristic initiation by RNA polymerase II at an adenosine. In promoters that combine M3 with either M5 or Inr, transcription initiation is regulated by the M3 motif.
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184
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Wang HY, Huang LJS, Liu Z, Garcia R, Li S, Galliani CA. Erythroblastic sarcoma presenting as bilateral ovarian masses in an infant with pure erythroid leukemia. Hum Pathol 2011; 42:749-58. [PMID: 21237494 DOI: 10.1016/j.humpath.2010.08.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2010] [Revised: 08/09/2010] [Accepted: 08/20/2010] [Indexed: 11/30/2022]
Abstract
Pure erythroid leukemia is a rare subtype of acute erythroid leukemia that is characterized by a predominant erythroid population, and erythroblastic sarcoma has not yet been described in the English literature. Here, we report a first case of erythroblastic sarcoma that presented as bilateral ovarian masses in a 3 ½-month-old infant girl with pure erythroid leukemia. Bone marrow aspirate and biopsy showed that the marrow was completely replaced by large-sized blasts consistent with erythroblasts. Immunophenotypically, both the tumor cells from the ovarian mass and bone marrow blasts were positive for CD117, glycophorin A, and hemoglobin A, demonstrating erythroid differentiation. Reverse transcriptase polymerase chain reaction showed that the tumor cells from ovarian mass expressed hemoglobin F and α1 spectrin, confirming their erythroid lineage. Conventional karyotype of the bone marrow aspirates revealed del(6)(q23q25) and trisomy 7 in all 21 cells examined. Fluorescence in situ hybridization of the ovarian mass demonstrated loss of c-myeloblastosis viral oncogene (C-MYB) at 6q23 locus in 41% of the cells, and deletion of chromosome 7 and 7q in 37% and 66% of cells, respectively. Taken together, we showed, for the first time, that pure erythroid leukemia presented as a myeloid sarcoma in the form of ovarian masses.
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Affiliation(s)
- Huan-You Wang
- Department of Pathology, University of California San Diego Health Sciences, La Jolla, CA 92037-0987, USA.
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185
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Tatevossian RG, Tang B, Dalton J, Forshew T, Lawson AR, Ma J, Neale G, Shurtleff SA, Bailey S, Gajjar A, Baker SJ, Sheer D, Ellison DW. MYB upregulation and genetic aberrations in a subset of pediatric low-grade gliomas. Acta Neuropathol 2010; 120:731-43. [PMID: 21046410 DOI: 10.1007/s00401-010-0763-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 10/16/2010] [Accepted: 10/19/2010] [Indexed: 12/18/2022]
Abstract
Recent studies of genetic abnormalities in pediatric low-grade gliomas (LGGs) have focused on activation of the ERK/MAPK pathway by KIAA1549-BRAF gene fusions in the majority of pilocytic astrocytomas (PAs) and by rare mutations in elements of the pathway across histopathologically diverse LGGs. This study reports that MYB, an oncogene not previously implicated in gliomagenesis, is activated in a diverse subset of pediatric LGGs. The study cohort comprised 57 pediatric LGGs and a comparative cohort of 59 pediatric high-grade gliomas (HGGs). The LGG cohort included 34 PAs and 23 diffuse gliomas; fibrillary astrocytomas (n = 14), oligodendroglial tumors (n = 7), and angiocentric gliomas (n = 2). MYB copy number abnormalities were disclosed using Affymetrix 6.0 SNP arrays and confirmed using interphase fluorescence in situ hybridization. Novel MYB amplifications that upregulate MYB RNA and protein expression were demonstrated in 2/14 diffuse astrocytomas. In addition, focal deletion of the terminal region of MYB was seen in 1 of 2 angiocentric gliomas (AGs). Increased expression of MYB was demonstrated by quantitative RT-PCR and immunohistochemistry. MYB upregulation at the protein level was demonstrated in a proportion of diffuse LGGs (60%), pilocytic astrocytomas (41%), and HGGs (19%), but abnormalities at the genomic level were only a feature of diffuse gliomas. Our data suggest that MYB may have a role in a subset of pediatric gliomas, through a variety of mechanisms in addition to MYB amplification and deletion.
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Affiliation(s)
- Ruth G Tatevossian
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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186
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Geng CD, Vedeckis WV. Use of recombinant cell-permeable small peptides to modulate glucocorticoid sensitivity of acute lymphoblastic leukemia cells. Biochemistry 2010; 49:8892-901. [PMID: 20831260 DOI: 10.1021/bi1007723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glucocorticoid (GC) hormones induce apoptosis in T-cell and pre-B-cell acute lymphoblastic leukemia (ALL) cells. Steroid-mediated apoptosis requires a threshold level of the glucocorticoid receptor (GR) protein, and increasing the intracellular GR levels in ALL cells would augment their hormone sensitivity. A protein transduction domain (PTD) approach was used to accomplish this. We produced an HIV Tat PTD domain fusion protein (Tat-GR(554-777)) that potentially competes for the degradation of GR protein by the ubiquitin-proteasome system and should thus increase its intracellular levels by "stabilizing" the GR. We also designed a fusion peptide for the c-Myb DNA binding domain, Tat-c-Myb DBD, since the biological function of this peptide as a dominant negative inhibitor of the c-Myb protein was already known. Purified, bacterially expressed Tat-c-Myb DBD and Tat-GR(554-777) exhibited highly efficient transduction into cultured ALL cell lines including 697 (pre-B-ALL) and CEM-C7 (T-ALL) cells. As expected, the transduced Tat-c-Myb DBD peptide inhibited steroid-mediated stimulation of a GR promoter-luciferase reporter gene. Significantly, transduced Tat-GR(554-777) effectively increased intracellular GR levels in the GC-resistant T-ALL cell line, CEM-C1, and in the pre-B-ALL 697 cell line. Furthermore, transduction of Tat-GR(554-777) rendered GC-resistant CEM-C1 cells sensitive to steroid killing and further sensitized 697 cells to steroid. The use of Tat-fusion peptide transduction may eventually lead to innovative therapeutic modalities to improve the clinical response of patients suffering from T-cell and pre-B-cell acute lymphoblastic leukemia by increasing steroid responsiveness and perhaps converting steroid-resistant leukemia to a hormone-responsive phenotype.
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Affiliation(s)
- Chuan-dong Geng
- Department of Biochemistry and Molecular Biology and Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
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187
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Yeang CH. An integrated analysis of molecular aberrations in NCI-60 cell lines. BMC Bioinformatics 2010; 11:495. [PMID: 20925909 PMCID: PMC2984587 DOI: 10.1186/1471-2105-11-495] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2010] [Accepted: 10/06/2010] [Indexed: 11/26/2022] Open
Abstract
Background Cancer is a complex disease where various types of molecular aberrations drive the development and progression of malignancies. Large-scale screenings of multiple types of molecular aberrations (e.g., mutations, copy number variations, DNA methylations, gene expressions) become increasingly important in the prognosis and study of cancer. Consequently, a computational model integrating multiple types of information is essential for the analysis of the comprehensive data. Results We propose an integrated modeling framework to identify the statistical and putative causal relations of various molecular aberrations and gene expressions in cancer. To reduce spurious associations among the massive number of probed features, we sequentially applied three layers of logistic regression models with increasing complexity and uncertainty regarding the possible mechanisms connecting molecular aberrations and gene expressions. Layer 1 models associate gene expressions with the molecular aberrations on the same loci. Layer 2 models associate expressions with the aberrations on different loci but have known mechanistic links. Layer 3 models associate expressions with nonlocal aberrations which have unknown mechanistic links. We applied the layered models to the integrated datasets of NCI-60 cancer cell lines and validated the results with large-scale statistical analysis. Furthermore, we discovered/reaffirmed the following prominent links: (1)Protein expressions are generally consistent with mRNA expressions. (2)Several gene expressions are modulated by composite local aberrations. For instance, CDKN2A expressions are repressed by either frame-shift mutations or DNA methylations. (3)Amplification of chromosome 6q in leukemia elevates the expression of MYB, and the downstream targets of MYB on other chromosomes are up-regulated accordingly. (4)Amplification of chromosome 3p and hypo-methylation of PAX3 together elevate MITF expression in melanoma, which up-regulates the downstream targets of MITF. (5)Mutations of TP53 are negatively associated with its direct target genes. Conclusions The analysis results on NCI-60 data justify the utility of the layered models for the incoming flow of cancer genomic data. Experimental validations on selected prominent links and application of the layered modeling framework to other integrated datasets will be carried out subsequently.
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Guillon-Munos A, Dambrine G, Richerioux N, Coupeau D, Muylkens B, Rasschaert D. The chicken miR-150 targets the avian orthologue of the functional zebrafish MYB 3'UTR target site. BMC Mol Biol 2010; 11:67. [PMID: 20813039 PMCID: PMC2940766 DOI: 10.1186/1471-2199-11-67] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Accepted: 09/02/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The c-myb proto-oncogene is the founding member of a family of transcription factors involved principally in haematopoiesis, in diverse organisms, from zebrafish to mammals. Its deregulation has been implicated in human leukaemogenesis and other cancers. The expression of c-myb is tightly regulated by post-transcriptional mechanisms involving microRNAs. MicroRNAs are small, highly conserved non-coding RNAs that inhibit translation and decrease mRNA stability by binding to regulatory motifs mostly located in the 3'UTR of target mRNAs conserved throughout evolution. MYB is an evolutionarily conserved miR-150 target experimentally validated in mice, humans and zebrafish. However, the functional miR-150 sites of humans and mice are orthologous, whereas that of zebrafish is different. RESULTS We identified the avian mature miRNA-150-5P, Gallus gallus gga-miR-150 from chicken leukocyte small-RNA libraries and showed that, as expected, the gga-miR-150 sequence was highly conserved, including the seed region sequence present in the other miR-150 sequences listed in miRBase. Reporter assays showed that gga-miR-150 acted on the avian MYB 3'UTR and identified the avian MYB target site involved in gga-miR-150 binding. A comparative in silico analysis of the miR-150 target sites of MYB 3'UTRs from different species led to the identification of a single set of putative target sites in amphibians and zebrafish, whereas two sets of putative target sites were identified in chicken and mammals. However, only the target site present in the chicken MYB 3'UTR that was identical to that in zebrafish was functional, despite the additional presence of mammalian target sites in chicken. This specific miR-150 site usage was not cell-type specific and persisted when the chicken c-myb 3'UTR was used in the cell system to identify mammalian target sites, showing that this miR-150 target site usage was intrinsic to the chicken c-myb 3'UTR. CONCLUSION Our study of the avian MYB/gga-miR-150 interaction shows a conservation of miR-150 target site functionality between chicken and zebrafish that does not extend to mammals.
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Affiliation(s)
- Audrey Guillon-Munos
- Université François Rabelais, Equipe Transcription, Lymphome Viro-induit, UFR Sciences et Techniques, Parc de Grandmont, F-37200 Tours, France
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189
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Stenman G, Andersson MK, Andrén Y. New tricks from an old oncogene: gene fusion and copy number alterations of MYB in human cancer. Cell Cycle 2010; 9:2986-95. [PMID: 20647765 DOI: 10.4161/cc.9.15.12515] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
MYB is a leucine zipper transcription factor that is essential for hematopoesis and for renewal of colonic crypts. There is also ample evidence showing that MYB is leukemogenic in several animal species. However, it was not until recently that clear evidence was presented showing that MYB actually is an oncogene rearranged in human cancer. In a recent study, a novel mechanism of activation of MYB involving gene fusion was identified in carcinomas of the breast and head and neck. A t(6;9) translocation was shown to generate fusions between MYB and the transcription factor gene NFIB. The fusions consistently result in loss of the 3'-end of MYB, including several highly conserved target sites for microRNAs that negatively regulate MYB expression. Deletion of these target sites may disrupt the repression of MYB, leading to overexpression of MYB-NFIB transcripts and protein and to transcriptional activation of critical MYB target genes associated with apoptosis, cell cycle control, cell growth/angiogenesis and cell adhesion. This study, together with previous and recent data showing rearrangements and copy number alterations of the MYB locus in T-cell leukemia and certain solid tumors, will be the main focus of this review.
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Affiliation(s)
- Göran Stenman
- Lundberg Laboratory for Cancer Research, Department of Pathology, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
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190
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Wang YT, Pan YJ, Cho CC, Lin BC, Su LH, Huang YC, Sun CH. A novel pax-like protein involved in transcriptional activation of cyst wall protein genes in Giardia lamblia. J Biol Chem 2010; 285:32213-26. [PMID: 20699219 DOI: 10.1074/jbc.m110.156620] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Giardia lamblia differentiates into infectious cysts to survive outside of the host. It is of interest to identify factors involved in up-regulation of cyst wall proteins (CWPs) during this differentiation. Pax proteins are important regulators of development and cell differentiation in Drosophila and vertebrates. No member of this gene family has been reported to date in yeast, plants, or protozoan parasites. We have identified a pax-like gene (pax1) encoding a putative paired domain in the G. lamblia genome. Epitope-tagged Pax1 localized to nuclei during both vegetative growth and encystation. Recombinant Pax1 specifically bound to the AT-rich initiator elements of the encystation-induced cwp1 to -3 and myb2 genes. Interestingly, overexpression of Pax1 increased cwp1 to -3 and myb2 gene expression and cyst formation. Deletion of the C-terminal paired domain or mutation of the basic amino acids of the paired domain resulted in a decrease of the transactivation function of Pax1. Our results indicate that the Pax family has been conserved during evolution, and Pax1 could up-regulate the key encystation-induced genes to regulate differentiation of the protozoan eukaryote, G. lamblia.
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Affiliation(s)
- Yi-Ting Wang
- Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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191
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MYB suppresses differentiation and apoptosis of human breast cancer cells. Breast Cancer Res 2010; 12:R55. [PMID: 20659323 PMCID: PMC2949644 DOI: 10.1186/bcr2614] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 06/25/2010] [Accepted: 07/26/2010] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION MYB is highly expressed in estrogen receptor positive (ER + ve) breast tumours and tumour cell lines. We recently demonstrated that MYB is essential for the proliferation of ER + ve breast cancer cells, and have now investigated its role in mammary epithelial differentiation. METHODS MCF-7 breast cancer cells were treated with sodium butyrate, vitamin E succinate or 12-O-tetradecanoylphorbol-13-acetate to induce differentiation as measured by Nile Red staining of lipid droplets and β-casein expression. The non-tumorigenic murine mammary epithelial cell (MEC) line, HC11, was induced to differentiate with lactogenic hormones. MYB levels were manipulated by inducible lentiviral shRNA-mediated knockdown and retroviral overexpression. RESULTS We found that MYB expression decreases following chemically-induced differentiation of the human breast cancer cell line MCF-7, and hormonally-induced differentiation of a non-tumorigenic murine mammary epithelial cell (MEC) line, HC11. We also found that shRNA-mediated MYB knockdown initiated differentiation of breast cancer cells, and greatly sensitised them to the differentiative and pro-apoptotic effects of differentiation-inducing agents (DIAs). Sensitisation to the pro-apoptotic effects DIAs is mediated by decreased expression of BCL2, which we show here is a direct MYB target in breast cancer cells. Conversely, enforced expression of MYB resulted in the cells remaining in an undifferentiated state, with concomitant suppression of apoptosis, in the presence of DIAs. CONCLUSIONS Taken together, these data imply that MYB function is critical in regulating the balance between proliferation, differentiation, and apoptosis in MECs. Moreover, our findings suggest MYB may be a viable therapeutic target in breast cancer and suggest specific approaches for exploiting this possibility.
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192
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Mitochondrial Hep27 is a c-Myb target gene that inhibits Mdm2 and stabilizes p53. Mol Cell Biol 2010; 30:3981-93. [PMID: 20547751 DOI: 10.1128/mcb.01284-09] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ever-expanding knowledge of the role of p53 in cellular metabolism, apoptosis, and cell cycle control has led to increasing interest in defining the stress response pathways that regulate Mdm2. In an effort to identify novel Mdm2 binding partners, we performed a large-scale immunoprecipitation of Mdm2 in the osteosarcoma U2OS cell line. One significant binding protein identified was Hep27, a member of the short-chain alcohol dehydrogenase/reductase (SDR) family of enzymes. Here, we demonstrate that the Hep27 preprotein contains an N-terminal mitochondrial targeting signal that is cleaved following mitochondrial import, resulting in mitochondrial matrix accumulation of mature Hep27. A fraction of the mitochondrial Hep27 translocates to the nucleus, where it binds to Mdm2 in the central domain, resulting in the attenuation of Mdm2-mediated p53 degradation. In addition, Hep27 is regulated at the transcriptional level by the proto-oncogene c-Myb and is required for c-Myb-induced p53 stabilization. Breast cancer gene expression analysis correlated estrogen receptor (ER) status with Hep27 expression and p53 function, providing a potential in vivo link between estrogen receptor signaling and p53 activity. Our data demonstrate a unique c-Myb-Hep27-Mdm2-p53 mitochondria-to-nucleus signaling pathway that may have functional significance for ER-positive breast cancers.
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193
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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: 6.6] [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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194
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c-Myb, Menin, GATA-3, and MLL form a dynamic transcription complex that plays a pivotal role in human T helper type 2 cell development. Blood 2010; 116:1280-90. [PMID: 20484083 DOI: 10.1182/blood-2009-05-223255] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
GATA-3 and c-Myb are core elements of a transcriptionally active complex essential for human Th2 cell development and maintenance. We report herein mechanistic details concerning the role of these transcription factors in human peripheral blood Th2 cell development. Silencing c-Myb in normal human naive CD4(+) cells under Th2 cell-promoting conditions blocked up-regulation of GATA-3 and interleukin-4, and in effector/memory CD4(+) T cells, decreased expression of GATA-3 and Th2 cytokines. In primary T cells, c-Myb allows GATA-3 to autoactivate its own expression, an event that requires the direct interaction of c-Myb and GATA-3 on their respective binding sites in promoter of GATA-3. Immunoprecipitation revealed that the c-Myb/GATA-3 complex contained Menin and mixed lineage leukemia (MLL). MLL recruitment into the c-Myb-GATA-3-Menin complex was associated with the formation Th2 memory cells. That MLL-driven epigenetic changes were mechanistically important for this transition was suggested by the fact that silencing c-Myb significantly decreased the methylation of histone H3K4 and the acetylation of histone H3K9 at the GATA-3 locus in developing Th2 and CD4(+) effector/memory cells. Therefore, c-Myb, GATA-3, and Menin form a core transcription complex that regulates GATA-3 expression and, with the recruitment of MLL, Th2 cell maturation in primary human peripheral blood T cells.
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195
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Myeloid-specific inactivation of p15Ink4b results in monocytosis and predisposition to myeloid leukemia. Blood 2010; 116:979-87. [PMID: 20457873 DOI: 10.1182/blood-2009-08-238360] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Inactivation of p15INK4b, an inhibitor of cyclin-dependent kinases, through DNA methylation is one of the most common epigenetic abnormalities in myeloid leukemia. Although this suggests a key role for this protein in myeloid disease suppression, experimental evidence to support this has not been reported. To address whether this event is critical for premalignant myeloid disorders and leukemia development, mice were generated that have loss of p15Ink4b specifically in myeloid cells. The p15Ink4b(fl/fl)-LysMcre mice develop nonreactive monocytosis in the peripheral blood accompanied by increased numbers of myeloid and monocytic cells in the bone marrow resembling the myeloproliferative form of chronic myelomonocytic leukemia. Spontaneous progression from chronic disease to acute leukemia was not observed. Nevertheless, MOL4070LTR retrovirus integrations provided cooperative genetic mutations resulting in a high frequency of myeloid leukemia in knockout mice. Two common retrovirus insertion sites near c-myb and Sox4 genes were identified, and their transcript up-regulated in leukemia, suggesting a collaborative role of their protein products with p15Ink4b-deficiency in promoting malignant disease. This new animal model demonstrates experimentally that p15Ink4b is a tumor suppressor for myeloid leukemia, and its loss may play an active role in the establishment of preleukemic conditions.
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Molvaersmyr AK, Saether T, Gilfillan S, Lorenzo PI, Kvaløy H, Matre V, Gabrielsen OS. A SUMO-regulated activation function controls synergy of c-Myb through a repressor-activator switch leading to differential p300 recruitment. Nucleic Acids Res 2010; 38:4970-84. [PMID: 20385574 PMCID: PMC2926607 DOI: 10.1093/nar/gkq245] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Synergy between transcription factors operating together on complex promoters is a key aspect of gene activation. The ability of specific factors to synergize is restricted by sumoylation (synergy control, SC). Focusing on the haematopoietic transcription factor c-Myb, we found evidence for a strong SC linked to SUMO-conjugation in its negative regulatory domain (NRD), while AMV v-Myb has escaped this control. Mechanistic studies revealed a SUMO-dependent switch in the function of NRD. When NRD is sumoylated, the activity of c-Myb is reduced. When sumoylation is abolished, NRD switches into being activating, providing the factor with a second activation function (AF). Thus, c-Myb harbours two AFs, one that is constitutively active and one in the NRD being SUMO-regulated (SRAF). This double AF augments c-Myb synergy at compound natural promoters. A similar SUMO-dependent switch was observed in the regulatory domains of Sp3 and p53. We show that the change in synergy behaviour correlates with a SUMO-dependent differential recruitment of p300 and a corresponding local change in histone H3 and H4 acetylation. We therefore propose a general model for SUMO-mediated SC, where SUMO controls synergy by determining the number and strength of AFs associated with a promoter leading to differential chromatin signatures.
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Yuan J, Crittenden RB, Bender TP. c-Myb promotes the survival of CD4+CD8+ double-positive thymocytes through upregulation of Bcl-xL. THE JOURNAL OF IMMUNOLOGY 2010; 184:2793-804. [PMID: 20142358 DOI: 10.4049/jimmunol.0902846] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mechanisms that regulate the lifespan of CD4(+)CD8(+) double-positive (DP) thymocytes help shape the peripheral T cell repertoire. However, the molecular mechanisms controlling DP thymocyte survival remain poorly understood. The Myb proto-oncogene encodes a transcription factor required during multiple stages of T cell development. We demonstrate that Myb mRNA expression is upregulated as thymocytes differentiate from the double-negative into the metabolically quiescent, small, preselection DP stage during T cell development. Using a conditional deletion mouse model, we demonstrate that Myb-deficient DP thymocytes undergo premature apoptosis, resulting in a limited Tcralpha repertoire biased toward 5' Jalpha segment usage. Premature apoptosis occurs specifically in the small preselection DP compartment in an alphabetaTCR-independent manner and is a consequence of decreased Bcl-xL expression. Forced Bcl-xL expression is able to rescue survival, and reintroduction of c-Myb restores both Bcl-xL expression and the small preselection DP compartment. We further demonstrate that c-Myb promotes transcription at the Bcl2l1 locus via a genetic pathway that is independent of the expression of T cell-specific factor-1 or RORgammat, two transcription factors that induce Bcl-xL expression in T cell development. Thus, Bcl-xL is a novel mediator of c-Myb activity during normal T cell development.
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Affiliation(s)
- Joan Yuan
- Department of Microbiology, Beirne B Carter Center for Immunology Research, University of Virginia Health System, Charlottesville, VA 22908, USA
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198
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Jin S, Zhao H, Yi Y, Nakata Y, Kalota A, Gewirtz AM. c-Myb binds MLL through menin in human leukemia cells and is an important driver of MLL-associated leukemogenesis. J Clin Invest 2010; 120:593-606. [PMID: 20093773 DOI: 10.1172/jci38030] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Accepted: 11/23/2009] [Indexed: 01/01/2023] Open
Abstract
Mixed-lineage leukemia (MLL) is a proto-oncogene frequently involved in chromosomal translocations associated with acute leukemia. These chromosomal translocations commonly result in MLL fusion proteins that dysregulate transcription. Recent data suggest that the MYB proto-oncogene, which is an important regulator of hematopoietic cell development, has a role in leukemogenesis driven by the MLL-ENL fusion protein, but exactly how is unclear. Here we have demonstrated that c-Myb is recruited to the MLL histone methyl transferase complex by menin, a protein important for MLL-associated leukemic transformation, and that it contributes substantially to MLL-mediated methylation of histone H3 at lysine 4 (H3K4). Silencing MYB in human leukemic cell lines and primary patient material evoked a global decrease in H3K4 methylation, an unexpected decrease in HOXA9 and MEIS1 gene expression, and decreased MLL and menin occupancy in the HOXA9 gene locus. This decreased occupancy was associated with a diminished ability of an MLL-ENL fusion protein to transform normal mouse hematopoietic cells. Previous studies have shown that MYB expression is regulated by Hoxa9 and Meis1, indicating the existence of an autoregulatory feedback loop. The finding that c-Myb has the ability to direct epigenetic marks, along with its participation in an autoregulatory feedback loop with genes known to transform hematopoietic cells, lends mechanistic and translationally relevant insight into its role in MLL-associated leukemogenesis.
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Affiliation(s)
- Shenghao Jin
- Division of Hematology/Oncology, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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199
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Sala A, Bettuzzi S, Pucci S, Chayka O, Dews M, Thomas-Tikhonenko A. Regulation of CLU gene expression by oncogenes and epigenetic factors implications for tumorigenesis. Adv Cancer Res 2010; 105:115-32. [PMID: 19879426 DOI: 10.1016/s0065-230x(09)05007-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In no other field has the function of clusterin (CLU) been more controversial than in cancer genetics. After more than 20 years of research, there is still uncertainty with regard to the role of CLU in human cancers. Some investigators believe CLU to be an oncogene, others-an inhibitor of tumorigenesis. However, owing to the recent efforts of several laboratories, the role of CLU in important cellular processes like proliferation, apoptosis, differentiation, and transformation is beginning to emerge. The "enigmatic" CLU is becoming less so. In this chapter, we will review the work of research teams interested in understanding how CLU is regulated by oncogenic signaling. We will discuss how and under what circumstances oncogenes and epigenetic factors modify CLU expression, with important consequences for mammalian tumorigenesis.
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Affiliation(s)
- Arturo Sala
- Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College London, United Kingdom
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200
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Wilczek C, Chayka O, Plachetka A, Klempnauer KH. Myb-induced chromatin remodeling at a dual enhancer/promoter element involves non-coding rna transcription and is disrupted by oncogenic mutations of v-myb. J Biol Chem 2010; 284:35314-24. [PMID: 19841477 DOI: 10.1074/jbc.m109.066175] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The oncogene v-myb of avian myeloblastosis virus (AMV) encodes a transcription factor (v-Myb) that transforms myelomonocytic cells by deregulating the expression of specific target genes. v-myb has acquired its oncogenic potential by truncation as well as by a number of point mutations of its cellular progenitor c-myb. As a result of these changes, the target gene spectrum v-Myb differs from that of c-Myb. We recently showed that the chicken mim-1 gene, a c-Myb target gene that is not activated by v-Myb harbors a powerful cell type-specific and Myb-inducible enhancer in addition to a Myb-responsive promoter. We now show that Myb-dependent activation of the mim-1 gene is accompanied by extensive remodeling of the nucleosomal architecture at the enhancer. We found that the mim-1 enhancer region also harbors a promoter whose activity is stimulated by Myb and which directs the transcription of an apparently non-coding RNA. Furthermore, our data show that the oncogenic mutations of AMV have disrupted the ability of v-Myb to induce remodeling of chromatin structure at the mim-1 enhancer. Together, our results demonstrate for the first time directly that Myb induces alterations of the nucleosomal organization at a relevant target site and provide new insight into the functional consequences of the oncogenic amino acid substitutions.
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Affiliation(s)
- Carola Wilczek
- Institut für Biochemie, Westfälische-Wilhelms-Universität Münster, D-48149 Münster, Germany
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