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Anand S, Vikramdeo KS, Sudan SK, Sharma A, Acharya S, Khan MA, Singh S, Singh AP. From modulation of cellular plasticity to potentiation of therapeutic resistance: new and emerging roles of MYB transcription factors in human malignancies. Cancer Metastasis Rev 2024; 43:409-421. [PMID: 37950087 PMCID: PMC11015973 DOI: 10.1007/s10555-023-10153-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 11/05/2023] [Indexed: 11/12/2023]
Abstract
MYB transcription factors are encoded by a large family of highly conserved genes from plants to vertebrates. There are three members of the MYB gene family in human, namely, MYB, MYBL1, and MYBL2 that encode MYB/c-MYB, MYBL1/A-MYB, and MYBL2/B-MYB, respectively. MYB was the first member to be identified as a cellular homolog of the v-myb oncogene carried by the avian myeloblastosis virus (AMV) causing leukemia in chickens. Under the normal scenario, MYB is predominantly expressed in hematopoietic tissues, colonic crypts, and neural stem cells and plays a role in maintaining the undifferentiated state of the cells. Over the years, aberrant expression of MYB genes has been reported in several malignancies and recent years have witnessed tremendous progress in understanding of their roles in processes associated with cancer development. Here, we review various MYB alterations reported in cancer along with the roles of MYB family proteins in tumor cell plasticity, therapy resistance, and other hallmarks of cancer. We also discuss studies that provide mechanistic insights into the oncogenic functions of MYB transcription factors to identify potential therapeutic vulnerabilities.
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Affiliation(s)
- Shashi Anand
- Department of Pathology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36617, USA
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
| | - Kunwar Somesh Vikramdeo
- Department of Pathology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36617, USA
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
| | - Sarabjeet Kour Sudan
- Department of Pathology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36617, USA
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
| | - Amod Sharma
- Department of Pathology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36617, USA
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
| | - Srijan Acharya
- Department of Pathology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36617, USA
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
| | - Mohammad Aslam Khan
- Department of Pathology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36617, USA
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
| | - Seema Singh
- Department of Pathology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36617, USA
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
- Department of Biochemistry and Molecular Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36688, USA
| | - Ajay Pratap Singh
- Department of Pathology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36617, USA.
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA.
- Department of Biochemistry and Molecular Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36688, USA.
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Han YJ, Zhang J, Hardeman A, Liu M, Karginova O, Romero R, Khramtsova GF, Zheng Y, Huo D, Olopade OI. An enhancer variant associated with breast cancer susceptibility in Black women regulates TNFSF10 expression and antitumor immunity in triple-negative breast cancer. Hum Mol Genet 2023; 32:139-150. [PMID: 35930348 PMCID: PMC9837834 DOI: 10.1093/hmg/ddac168] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 07/13/2022] [Accepted: 07/15/2022] [Indexed: 01/25/2023] Open
Abstract
Women of African ancestry have the highest mortality from triple-negative breast cancer (TNBC) of all racial groups. To understand the genomic basis of breast cancer in the populations, we previously conducted genome-wide association studies and identified single nucleotide polymorphisms (SNPs) associated with breast cancer in Black women. In this study, we investigated the functional significance of the top associated SNP rs13074711. We found the SNP served as an enhancer variant and regulated TNFSF10 (TRAIL) expression in TNBC cells, with a significant association between the SNP genotype and TNFSF10 expression in breast tumors. Mechanistically, rs13074711 modulated the binding activity of c-MYB at the motif and thereby controlled TNFSF10 expression. Interestingly, TNFSF10 expression in many cancers was consistently lower in African Americans compared with European Americans. Furthermore, TNFSF10 expression in TNBC was significantly correlated with the expression of antiviral immune genes and was regulated by type I interferons (IFNs). Accordingly, loss of TNFSF10 resulted in a profound decrease in apoptosis of TNBC cells in response to type I IFNs and poly(I:C), a synthetic analogue of double stranded virus. Lastly, in a syngeneic mouse model of breast cancer, TNFSF10-deficiency in breast tumors decreased tumor-infiltrated CD4+ and CD8+ T cell quantities. Collectively, our results suggested that TNFSF10 plays an important role in the regulation of antiviral immune responses in TNBC, and the expression is in part regulated by a genetic variant associated with breast cancer in Black women. Our results underscore the important contributions of genetic variants to immune defense mechanisms.
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Affiliation(s)
- Yoo Jane Han
- Section of Hematology/Oncology & Center for Clinical Cancer Genetics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Jing Zhang
- Section of Hematology/Oncology & Center for Clinical Cancer Genetics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Ashley Hardeman
- Section of Hematology/Oncology & Center for Clinical Cancer Genetics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Margaret Liu
- Section of Hematology/Oncology & Center for Clinical Cancer Genetics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Olga Karginova
- Section of Hematology/Oncology & Center for Clinical Cancer Genetics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Roger Romero
- Section of Hematology/Oncology & Center for Clinical Cancer Genetics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Galina F Khramtsova
- Section of Hematology/Oncology & Center for Clinical Cancer Genetics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Yonglan Zheng
- Section of Hematology/Oncology & Center for Clinical Cancer Genetics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Dezheng Huo
- Department of Public Health Sciences, University of Chicago, Chicago, IL 60637, USA
| | - Olufunmilayo I Olopade
- Section of Hematology/Oncology & Center for Clinical Cancer Genetics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
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Wijeratne TU, Guiley KZ, Lee HW, Müller GA, Rubin SM. Cyclin-dependent kinase-mediated phosphorylation and the negative regulatory domain of transcription factor B-Myb modulate its DNA binding. J Biol Chem 2022; 298:102319. [PMID: 35926712 PMCID: PMC9478404 DOI: 10.1016/j.jbc.2022.102319] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 11/25/2022] Open
Abstract
B-Myb is a highly conserved member of the vertebrate Myb family of transcription factors that plays a critical role in cell-cycle progression and proliferation. Myb proteins activate Myb-dependent promoters by interacting specifically with Myb-binding site (MBS) sequences using their DNA-binding domain (DBD). Transactivation of MBS promoters by B-Myb is repressed by its negative regulatory domain (NRD), and phosphorylation of the NRD by Cdk2-CyclinA relieves the repression to activate B-Myb–dependent promoters. However, the structural mechanisms underlying autoinhibition and activation of B-Myb–mediated transcription have been poorly characterized. Here, we determined that a region in the B-Myb NRD (residues 510–600) directly associates with the DBD and inhibits binding of the DBD to the MBS DNA sequence. We demonstrate using biophysical assays that phosphorylation of the NRD at T515, T518, and T520 is sufficient to disrupt the interaction between the NRD and the DBD, which results in increased affinity for MBS DNA and increased B-Myb–dependent promoter activation in cell assays. Our biochemical characterization of B-Myb autoregulation and the activating effects of phosphorylation provide insight into how B-Myb functions as a site-specific transcription factor.
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Affiliation(s)
- Tilini U Wijeratne
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Keelan Z Guiley
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Hsiau-Wei Lee
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Gerd A Müller
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
| | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
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Wang L, Dai W, Shi Y, Wang Y, Zhang C. Cloning and activity analysis of the highly expressed gene VviABCG20 promoter in seed and its activity is negatively regulated by the transcription factor VviDof14. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 315:111152. [PMID: 35067313 DOI: 10.1016/j.plantsci.2021.111152] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 12/09/2021] [Accepted: 12/11/2021] [Indexed: 06/14/2023]
Abstract
Half-size ATP binding cassette G (ABCG) transporters participate in the growth and development of plants by transporting substrates. The VviABCG20 gene is highly expressed in seed and plays an important role in seed development/abortion. However, little is known about the function of the VviABCG20 promoter (pVviABCG20) and its regulatory factors. In our study, we obtained pVviABCG20s from 15 seeded and seedless grape varieties and there were two types of 'a' and 'b' with 41 bp non-deletion or deletion, respectively. The pVviABCG20 activity was higher in seeds, siliques, flowers and roots of pVviABCG20-GUS Arabidopsis. The GUS activity analysis revealed that the activities of P4 (-586 bp) to P7 (-155 bp) were becoming increasingly weaker, and the P7 activity almost disappears compared with the pVviABCG20 (P0, -1604). Yeast one-hybrid and GUS activity analysis indicated that VviDof14 binds to the AAAG element in the P7' (-586 bp) fragment of the pVviABCG20 and regulated the activity negatively. The quantitative real-time PCR analysis suggested that the expression of VviDof14 in Thompson seedless seeds was higher than that in Pinot noir. Our study laid the foundation for further analysis of the functions of the pVviABCG20 and its regulator VviDof14 in grape seed development/abortion.
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Affiliation(s)
- Ling Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northwest Region), Ministry of Agriculture, P.R. China, Yangling, Shaanxi, China
| | - Weina Dai
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northwest Region), Ministry of Agriculture, P.R. China, Yangling, Shaanxi, China
| | - Yuanyuan Shi
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northwest Region), Ministry of Agriculture, P.R. China, Yangling, Shaanxi, China
| | - Yuejin Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northwest Region), Ministry of Agriculture, P.R. China, Yangling, Shaanxi, China
| | - Chaohong Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northwest Region), Ministry of Agriculture, P.R. China, Yangling, Shaanxi, China.
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Lemma RB, Ledsaak M, Fuglerud BM, Sandve GK, Eskeland R, Gabrielsen OS. Chromatin occupancy and target genes of the haematopoietic master transcription factor MYB. Sci Rep 2021; 11:9008. [PMID: 33903675 PMCID: PMC8076236 DOI: 10.1038/s41598-021-88516-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 04/13/2021] [Indexed: 02/02/2023] Open
Abstract
The transcription factor MYB is a master regulator in haematopoietic progenitor cells and a pioneer factor affecting differentiation and proliferation of these cells. Leukaemic transformation may be promoted by high MYB levels. Despite much accumulated molecular knowledge of MYB, we still lack a comprehensive understanding of its target genes and its chromatin action. In the present work, we performed a ChIP-seq analysis of MYB in K562 cells accompanied by detailed bioinformatics analyses. We found that MYB occupies both promoters and enhancers. Five clusters (C1-C5) were found when we classified MYB peaks according to epigenetic profiles. C1 was enriched for promoters and C2 dominated by enhancers. C2-linked genes were connected to hematopoietic specific functions and had GATA factor motifs as second in frequency. C1 had in addition to MYB-motifs a significant frequency of ETS-related motifs. Combining ChIP-seq data with RNA-seq data allowed us to identify direct MYB target genes. We also compared ChIP-seq data with digital genomic footprinting. MYB is occupying nearly a third of the super-enhancers in K562. Finally, we concluded that MYB cooperates with a subset of the other highly expressed TFs in this cell line, as expected for a master regulator.
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Affiliation(s)
- Roza B Lemma
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo, 0318, Oslo, Norway
| | - Marit Ledsaak
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway
- Institute of Basic Medical Sciences, Department of Molecular Medicine, University of Oslo, Blindern, PO Box 1112, 0317, Oslo, Norway
| | - Bettina M Fuglerud
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway
- Terry Fox Laboratory, BC Cancer, Vancouver, BC, V5Z 1L3, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Geir Kjetil Sandve
- Department of Informatics, University of Oslo, Blindern, PO Box 1080, 0371, Oslo, Norway
| | - Ragnhild Eskeland
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway
- Institute of Basic Medical Sciences, Department of Molecular Medicine, University of Oslo, Blindern, PO Box 1112, 0317, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Odd S Gabrielsen
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway.
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MYB oncoproteins: emerging players and potential therapeutic targets in human cancer. Oncogenesis 2021; 10:19. [PMID: 33637673 PMCID: PMC7910556 DOI: 10.1038/s41389-021-00309-y] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 01/31/2023] Open
Abstract
MYB transcription factors are highly conserved from plants to vertebrates, indicating that their functions embrace fundamental mechanisms in the biology of cells and organisms. In humans, the MYB gene family is composed of three members: MYB, MYBL1 and MYBL2, encoding the transcription factors MYB, MYBL1, and MYBL2 (also known as c-MYB, A-MYB, and B-MYB), respectively. A truncated version of MYB, the prototype member of the MYB family, was originally identified as the product of the retroviral oncogene v-myb, which causes leukaemia in birds. This led to the hypothesis that aberrant activation of vertebrate MYB could also cause cancer. Despite more than three decades have elapsed since the isolation of v-myb, only recently investigators were able to detect MYB genes rearrangements and mutations, smoking gun evidence of the involvement of MYB family members in human cancer. In this review, we will highlight studies linking the activity of MYB family members to human malignancies and experimental therapeutic interventions tailored for MYB-expressing cancers.
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Werwein E, Biyanee A, Klempnauer KH. Intramolecular interaction of B-MYB is regulated through Ser-577 phosphorylation. FEBS Lett 2020; 594:4266-4279. [PMID: 32979888 DOI: 10.1002/1873-3468.13940] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/11/2020] [Accepted: 09/08/2020] [Indexed: 02/02/2023]
Abstract
The transcription factor B-MYB is an important regulator of cell cycle-related processes that is activated by step-wise phosphorylation of multiple sites by cyclin-dependent kinases (CDKs) and conformational changes induced by the peptidylprolyl cis/trans isomerase Pin1. Here, we show that a conserved amino acid sequence around Ser-577 in the C-terminal part of B-MYB is able to interact with the B-MYB DNA-binding domain. Phosphorylation of Ser-577 disrupts this interaction and is regulated by the interplay of CDKs and the phosphatase CDC14B. Deletion of sequences surrounding Ser-577 hyperactivates the transactivation potential of B-MYB, decreases its proteolytic stability, and causes cell cycle defects. Overall, we show for the first time that B-MYB can undergo an intramolecular interaction that is controlled by the phosphorylation state of Ser-577.
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Affiliation(s)
- Eugen Werwein
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, Münster, Germany
| | - Abhiruchi Biyanee
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, Münster, Germany
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Hsu HM, Huang YH, Aryal S, Liu HW, Chen C, Chen SH, Chu CH, Tai JH. Endomembrane Protein Trafficking Regulated by a TvCyP2 Cyclophilin in the Protozoan Parasite, Trichomonas vaginalis. Sci Rep 2020; 10:1275. [PMID: 31988345 PMCID: PMC6985235 DOI: 10.1038/s41598-020-58270-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 01/10/2020] [Indexed: 01/08/2023] Open
Abstract
In Trichomonas vaginalis, the TvCyP1-catalyzed conformational switches of two glycinyl-prolyl imide bonds in Myb3 were previously shown to regulate the trafficking of Myb3 from cytoplasmic membrane compartments towards the nucleus. In this study, TvCyP2 was identified as a second cyclophilin that binds to Myb3 at the same dipeptide motifs. The enzymatic proficiency of TvCyP2, but not its binding to Myb3, was aborted by a mutation of Arg75 in the catalytic domain. TvCyP2 was localized to the endoplasmic reticulum with a weak signal that extensively extends into the cytoplasm as well as to the plasma membrane according to an immunofluorescence assay. Moreover, TvCyP2 was co-enriched with TvCyP1 and Myb3 in various membrane fractions purified by differential and gradient centrifugation. TvCyP2 was found to proficiently enzymatically regulate the distribution of TvCyP1 and Myb3 among purified membrane fractions, and to localize TvCyP1 in hydrogenosomes and on plasma membranes. Protein complexes immunoprecipitated from lysates of cells overexpressing TvCyP1 and TvCyP2 were found to share some common components, like TvCyP1, TvCyP2, TvBip, Myb3, TvHSP72, and the hydrogenosomal heat shock protein 70 (HSP70). Direct interaction between TvCyP1 and TvCyP2 was confirmed by a GST pull-down assay. Fusion of vesicles with hydrogenosomes was observed by transmission electron microscopy, whereas TvCyP1, TvCyP2, and Myb3 were each detected at the fusion junction by immunoelectron microscopy. These observations suggest that T. vaginalis may have evolved a novel protein trafficking pathway to deliver proteins among the endomembrane compartments, hydrogenosomes and plasma membranes.
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Affiliation(s)
- Hong-Ming Hsu
- Department of Tropical Medicine and Parasitology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-Hsin Huang
- Division of Infectious Diseases and Immunology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Sarita Aryal
- Structural Biology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsing-Wei Liu
- Division of Infectious Diseases and Immunology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chinpan Chen
- Structural Biology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Shu-Hui Chen
- Department of Chemistry, National Cheng Kung University, Tainan, Taiwan
| | - Chien-Hsin Chu
- Division of Infectious Diseases and Immunology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
| | - Jung-Hsiang Tai
- Department of Tropical Medicine and Parasitology, College of Medicine, National Taiwan University, Taipei, Taiwan. .,Division of Infectious Diseases and Immunology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
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Tombuloglu H. Genome-wide identification and expression analysis of R2R3, 3R- and 4R-MYB transcription factors during lignin biosynthesis in flax (Linum usitatissimum). Genomics 2019; 112:782-795. [PMID: 31128265 DOI: 10.1016/j.ygeno.2019.05.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/06/2019] [Accepted: 05/20/2019] [Indexed: 11/19/2022]
Abstract
MYB transcription factors (TFs) have vital roles in regulating lignin or fiber development. Flax (Linum usitatissimum) is known as one of the plants with high fiber production capacity. However, no studies have been conducted to identify and characterize MYB TFs in the flax genome. Results showed that flax genome harbours 167 R2R3, seven 3R, and one 4R-type MYB TFs. 22 MYB genes (%13) were estimated to be tandem duplicated dated around 13.3-86.98 Mya. 130 flax MYB members have apparent orthologous with Arabidopsis, in which 17 R2R3 MYBs are associated with lignin biosynthesis. MYB062, MYB072, MYB096, MYB141, and MYB146 genes were up-regulated in tissues having higher lignin production capacity. In opposite, MYB012 and MYB113 genes were down-regulated which points out the involvement of those genes in the lignin biosynthesis mechanism. This comprehensive study can provide a basis for understanding the role of MYBs in fiber or lignin production in flax.
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Affiliation(s)
- Huseyin Tombuloglu
- Department of Genetics Research, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, P.O. Box 1982, 31441 Dammam, Saudi Arabia.
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Wang X, Angelis N, Thein SL. MYB - A regulatory factor in hematopoiesis. Gene 2018; 665:6-17. [PMID: 29704633 PMCID: PMC10764194 DOI: 10.1016/j.gene.2018.04.065] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/06/2018] [Accepted: 04/23/2018] [Indexed: 01/07/2023]
Abstract
MYB is a transcription factor which was identified in birds as a viral oncogene (v-MYB). Its cellular counterpart was subsequently isolated as c-MYB which has three functional domains - DNA binding domain, transactivation domain and negative regulatory domain. c-MYB is essential for survival, and deletion of both alleles of the gene results in embryonic death. It is highly expressed in hematopoietic cells, thymus and neural tissue, and required for T and B lymphocyte development and erythroid maturation. Additionally, aberrant MYB expression has been found in numerous solid cancer cells and human leukemia. Recent studies have also implicated c-MYB in the regulation of expression of fetal hemoglobin which is highly beneficial to the β-hemoglobinopathies (beta thalassemia and sickle cell disease). These findings suggest that MYB could be a potential therapeutic target in leukemia, and possibly also a target for therapeutic increase of fetal hemoglobin in the β-hemoglobinopathies.
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Affiliation(s)
- Xunde Wang
- National Heart, Lung and Blood Institute/NIH, Sickle Cell Branch, Bethesda, USA
| | - Nikolaos Angelis
- National Heart, Lung and Blood Institute/NIH, Sickle Cell Branch, Bethesda, USA
| | - Swee Lay Thein
- National Heart, Lung and Blood Institute/NIH, Sickle Cell Branch, Bethesda, USA.
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Chu CH, Huang YH, Liu HW, Hsu HM, Tai JH. Membrane localization of a Myb3 transcription factor regulated by a TvCyP1 cyclophilin in the parasitic protozoan Trichomonas vaginalis. FEBS J 2018; 285:929-946. [PMID: 29282865 DOI: 10.1111/febs.14374] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 11/24/2017] [Accepted: 12/21/2017] [Indexed: 11/28/2022]
Abstract
In Trichomonas vaginalis, a TvCyP1 cyclophilin was previously demonstrated to regulate the nuclear translocation of Myb1 and Myb3, which respectively repress and activate transcription of an adhesion protein ap65-1 gene. In the present study, TvCyP1 was found to bind to Myb3 at sites spanning 54 Gly-Pro55 and 72 Gly-Pro73 with differential affinities. When Gly54 and Gly72 in Myb3 were both mutated, the mutant protein was restrained on outer membranes of hydrogenosomes and some cytoplasmic vesicles. In the purified Myb3 protein complex, a high molecular weight Myb3-interacting protein (Myb3IPhmw ) and a 72-kDa heat shock protein (TvHSP72) were identified and characterized, with direct binding of Myb3 to Myb3IPhmw and TvHSP72 confirmed in vitro. When cell lysates were fractionated by the differential and gradient centrifugations, TvCyP1 and Myb3 were always associated with membrane fractions enriched with Myb3IPhmw and Myb1, as well as hydrogenosomes and VMyb organelle fractions. Mutations of Gly54 and/or Gly72 resulted in membrane redistribution of Myb3 and the aberrant assembly of the Myb3 protein complex. Consistent with these findings, the involvement of TvCyP1 in membrane distribution of Myb3, and dissociation of Myb3 from TvCyP1 protein complex were demonstrated, with direct interactions between TvCyP1 and Myb3IPhmw and that between TvCyP1 and TvHSP72, confirmed in vitro. These observations suggest that TvCyP1 directly binds to Myb3 and some of its interacting proteins to mediate serial conformational switches of Myb3 for its transition from the membrane compartments toward the nucleus.
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Affiliation(s)
- Chien-Hsin Chu
- Division of Infectious Diseases and Immunology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yu-Hsin Huang
- Division of Infectious Diseases and Immunology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsing-Wei Liu
- Division of Infectious Diseases and Immunology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hong-Ming Hsu
- Department of Parasitology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jung-Hsiang Tai
- Division of Infectious Diseases and Immunology, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Department of Parasitology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Feng G, Burleigh JG, Braun EL, Mei W, Barbazuk WB. Evolution of the 3R-MYB Gene Family in Plants. Genome Biol Evol 2017; 9:1013-1029. [PMID: 28444194 PMCID: PMC5405339 DOI: 10.1093/gbe/evx056] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2017] [Indexed: 12/13/2022] Open
Abstract
Plant 3R-MYB transcription factors are an important subgroup of the MYB super family in plants; however, their evolutionary history and functions remain poorly understood. We identified 225 3R-MYB proteins from 65 plant species, including algae and all major lineages of land plants. Two segmental duplication events preceding the common ancestor of angiosperms have given rise to three subgroups of the 3R-MYB proteins. Five conserved introns in the domain region of the 3R-MYB genes were identified, which arose through a step-wise pattern of intron gain during plant evolution. Alternative splicing (AS) analysis of selected species revealed that transcripts from more than 60% of 3R-MYB genes undergo AS. AS could regulate transcriptional activity for some of the plant 3R-MYBs by generating different regulatory motifs. The 3R-MYB genes of all subgroups appear to be enriched for Mitosis-Specific Activator element core sequences within their upstream promoter region, which suggests a functional involvement in cell cycle. Notably, expression of 3R-MYB genes from different species exhibits differential regulation under various abiotic stresses. These data suggest that the plant 3R-MYBs function in both cell cycle regulation and abiotic stress response, which may contribute to the adaptation of plants to a sessile lifestyle.
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Affiliation(s)
- Guanqiao Feng
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL
| | - John Gordon Burleigh
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL.,Department of Biology, University of Florida, Gainesville, FL.,Genetics Institute, University of Florida, Gainesville, FL
| | - Edward L Braun
- Department of Biology, University of Florida, Gainesville, FL.,Genetics Institute, University of Florida, Gainesville, FL
| | - Wenbin Mei
- Department of Biology, University of Florida, Gainesville, FL
| | - William Bradley Barbazuk
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL.,Department of Biology, University of Florida, Gainesville, FL.,Genetics Institute, University of Florida, Gainesville, FL
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PIAS1 binds p300 and behaves as a coactivator or corepressor of the transcription factor c-Myb dependent on SUMO-status. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:705-18. [PMID: 27032383 DOI: 10.1016/j.bbagrm.2016.03.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 03/08/2016] [Accepted: 03/23/2016] [Indexed: 12/21/2022]
Abstract
The PIAS proteins (Protein Inhibitor of Activated STATs) constitute a family of multifunctional nuclear proteins operating as SUMO E3 ligases and being involved in a multitude of interactions. They participate in a range of biological processes, also beyond their well-established role in the immune system and cytokine signalling. They act both as transcriptional corepressors and coactivators depending on the context. In the present work, we investigated mechanisms by which PIAS1 causes activation or repression of c-Myb dependent target genes. Analysis of global expression data shows that c-Myb and PIAS1 knockdowns affect a subset of common targets, but with a dual outcome consistent with a role of PIAS1 as either a corepressor or coactivator. Our mechanistic studies show that PIAS1 engages in a novel interaction with the acetyltransferase and coactivator p300. Interaction and ChIP analysis suggest a bridging function where PIAS1 enhances p300 recruitment to c-Myb-bound sites through interaction with both proteins. In addition, the E3 activity of PIAS1 enhances further its coactivation. Remarkably, the SUMO status of c-Myb had a decisive role, indicating a SUMO-dependent switch in the way PIAS1 affects c-Myb, either as a coactivator or corepressor. Removal of the two major SUMO-conjugation sites in c-Myb (2KR mutant), which enhances its activity significantly, turned PIAS1 into a corepressor. Also, p300 was less efficiently recruited to chromatin by c-Myb-2KR. We propose that PIAS1 acts as a "protein inhibitor of activated c-Myb" in the absence of SUMOylation while, in its presence, PIAS behaves as a "protein activator of repressed c-Myb".
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Abstract
Strict control of tissue-specific gene expression plays a pivotal role during lineage commitment. The transcription factor c-Myb has an essential role in adult haematopoiesis and functions as an oncogene when rearranged in human cancers. Here we have exploited digital genomic footprinting analysis to obtain a global picture of c-Myb occupancy in the genome of six different haematopoietic cell-types. We have biologically validated several c-Myb footprints using c-Myb knockdown data, reporter assays and DamID analysis. We show that our predicted conserved c-Myb footprints are highly dependent on the haematopoietic cell type, but that there is a group of gene targets common to all cell-types analysed. Furthermore, we find that c-Myb footprints co-localise with active histone mark H3K4me3 and are significantly enriched at exons. We analysed co-localisation of c-Myb footprints with 104 chromatin regulatory factors in K562 cells, and identified nine proteins that are enriched together with c-Myb footprints on genes positively regulated by c-Myb and one protein enriched on negatively regulated genes. Our data suggest that c-Myb is a transcription factor with multifaceted target regulation depending on cell type.
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Hsu HM, Chu CH, Wang YT, Lee Y, Wei SY, Liu HW, Ong SJ, Chen C, Tai JH. Regulation of nuclear translocation of the Myb1 transcription factor by TvCyclophilin 1 in the protozoan parasite Trichomonas vaginalis. J Biol Chem 2014; 289:19120-36. [PMID: 24831011 DOI: 10.1074/jbc.m114.549410] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In Trichomonas vaginalis, a Myb1 protein was previously demonstrated to repress transcription of an iron-inducible ap65-1 gene. In this study, a human cyclophilin A homologue, TvCyclophilin 1 (TvCyP1), was identified as a Myb1-binding protein using a bacterial two-hybrid library screening system. The recombinant TvCyP1 exhibited typical peptidyl-prolyl isomerase activity with kcat/Km of ∼7.1 μm(-1) s(-1). In a pulldown assay, the His-tagged Myb1 interacted with a GST-TvCyP1 fusion protein, which had an enzymatic proficiency half that of recombinant TvCyP1. Both the enzymatic proficiency of GST-TvCyP1 and its binding to His-Myb1 were eliminated by mutation of Arg(63) in the catalytic motif or inhibited by cyclosporin A. TvCyP1 was primarily localized to the hydrogenosomes by immunofluorescence assay, but it was also co-purified with Myb1 in certain vesicle fractions from differential and gradient centrifugations. Transgenic cells overexpressing HA-TvCyP1 had a higher level of nuclear Myb1 but a much lower level of Myb1 associated with the vesicles than control and those overexpressing HA-TvCyP1(R63A). Myb1 was detected at a much higher level in the HA-TvCyP1 protein complex than in the HA-TvCyP1(R63A) protein complex immunoprecipitated from P15 and P100, but not S100, fractions of postnuclear lysates. A TvCyP1-binding motif, (105)YGPKWNK(111), was identified in Myb1 in which Gly(106) and Pro(107) were essential for its binding to TvCyP1. Mutation of Gly(106) and Pro(107), respectively, in HA-Myb1 resulted in cytoplasmic retention and elevated nuclear translocation of the overexpressed protein. These results suggest that TvCyP1 may induce the release of Myb1 that is restrained to certain cytoplasmic vesicles prior to its nuclear translocation.
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Affiliation(s)
| | - Chien-Hsin Chu
- Divisions of Infectious Diseases and Immunology and From the Department of Parasitology, College of Medicine, National Taiwan University and
| | - Ya-Ting Wang
- From the Department of Parasitology, College of Medicine, National Taiwan University and
| | - Yu Lee
- Divisions of Infectious Diseases and Immunology and
| | - Shu-Yi Wei
- Structure Biology, Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | | | - Shiou-Jeng Ong
- From the Department of Parasitology, College of Medicine, National Taiwan University and
| | - Chinpan Chen
- Structure Biology, Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Jung-Hsiang Tai
- Divisions of Infectious Diseases and Immunology and From the Department of Parasitology, College of Medicine, National Taiwan University and
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A supervised network analysis on gene expression profiles of breast tumors predicts a 41-gene prognostic signature of the transcription factor MYB across molecular subtypes. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2014; 2014:813067. [PMID: 24639887 PMCID: PMC3930188 DOI: 10.1155/2014/813067] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 10/07/2013] [Accepted: 10/20/2013] [Indexed: 02/05/2023]
Abstract
Background. MYB is predicted to be a favorable prognostic predictor in a breast cancer population. We proposed to find the inferred mechanism(s) relevant to the prognostic features of MYB via a supervised network analysis. Methods. Both coefficient of intrinsic dependence (CID) and Galton Pierson's correlation coefficient (GPCC) were combined and designated as CIDUGPCC. It is for the univariate network analysis. Multivariate CID is for the multivariate network analysis. Other analyses using bioinformatic tools and statistical methods are included. Results. ARNT2 is predicted to be the essential gene partner of MYB. We classified four prognostic relevant gene subpools in three breast cancer cohorts as feature types I–IV. Only the probes in feature type II are the potential prognostic feature of MYB. Moreover, we further validated 41 prognosis relevant probes to be the favorable prognostic signature. Surprisingly, two additional family members of MYB are elevated to promote poor prognosis when both levels of MYB and ARNT2 decline. Both MYBL1 and MYBL2 may partially decrease the tumor suppressive activities that are predicted to be up-regulated by MYB and ARNT2. Conclusions. The major prognostic feature of MYB is predicted to be determined by the MYB subnetwork (41 probes) that is relevant across subtypes.
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Arratia J, Aguirre J. Los factores de transcripción tipo Myb, una familia de reguladores de la diferenciación celular conservada en los organismos eucariontes. TIP REVISTA ESPECIALIZADA EN CIENCIAS QUÍMICO-BIOLÓGICAS 2013. [DOI: 10.1016/s1405-888x(13)72081-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Prouse MB, Campbell MM. The interaction between MYB proteins and their target DNA binding sites. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1819:67-77. [DOI: 10.1016/j.bbagrm.2011.10.010] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 10/17/2011] [Accepted: 10/18/2011] [Indexed: 02/02/2023]
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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: 3.4] [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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Morse AM, Whetten RW, Dubos C, Campbell MM. Post-translational modification of an R2R3-MYB transcription factor by a MAP Kinase during xylem development. THE NEW PHYTOLOGIST 2009; 183:1001-1013. [PMID: 19566814 DOI: 10.1111/j.1469-8137.2009.02900.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Despite the pivotal role played by R2R3-MYB family members in the regulation of plant gene expression, little is known about post-translational regulation of these proteins. In animals, the MYB family member, c-MYB, is post-translationally modified by a mitogen-activated protein kinase (MAPK), p42(mapk). In order to test the hypothesis that R2R3-MYB proteins may be regulated by MAPK activity, interplay between a R2R3-MYB family member expressed in differentiating pine xylem (Pinus taeda MYB4, PtMYB4) and MAPK proteins expressed in the same tissue was examined. One of the MAPK proteins expressed in pine xylem, PtMAPK6, phosphorylated PtMYB4. Recombinant PtMAPK6 phosphorylated PtMYB4 on serine-236, located in the C-terminal activation domain of this transcription factor in a context that is found in other plant MYB proteins. Modification of the PtMAPK6 target serine in PtMYB4 did not appear to alter DNA binding in vitro but did alter the ability of PtMYB4 to promote transcriptional activation in yeast. PtMAPK6 activity was detected in developing xylem cells that had ceased cell division and formed secondary walls. Together, the data support a role for PtMAPK6 during early xylem development and suggest a function for this kinase in regulating gene expression through phosphorylation of PtMYB4.
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Affiliation(s)
- Alison M Morse
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - Ross W Whetten
- Department of Forestry and Environmental Resources, North Carolina State University, 5231 Jordan Hall, Box 8008, Raleigh, NC, 27695, USA
| | - Christian Dubos
- Centre for the Analysis of Genome Evolution & Function, Department of Cell & Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, Canada, M5S 3B2
| | - Malcolm M Campbell
- Centre for the Analysis of Genome Evolution & Function, Department of Cell & Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, Canada, M5S 3B2
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Rønneberg JA, Tost J, Solvang HK, Alnaes GIG, Johansen FE, Brendeford EM, Yakhini Z, Gut IG, Lønning PE, Børresen-Dale AL, Gabrielsen OS, Kristensen VN. GSTP1 promoter haplotypes affect DNA methylation levels and promoter activity in breast carcinomas. Cancer Res 2008; 68:5562-71. [PMID: 18632608 DOI: 10.1158/0008-5472.can-07-5828] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The CpG island spanning the transcription start of the glutathione S-transferase P1 becomes methylated in a variety of human cancers including breast cancer. To study the effect of sequence variation on hypermethylation of the GSTP1 promoter, we analyzed the genetic and epigenetic variability in 90 tumors from patients with locally advanced breast cancer. High-resolution quantitative analysis revealed large variability in the DNA methylation levels. Lack of methylation was more often observed in the basal and normal-like estrogen receptor (ER)-negative tumors, and methylated GSTP1 was associated with better overall survival (P = 0.00063). Studies of the genetic variation identified 14 different haplotypes. The distribution of methylation levels of tumors homozygous for the most frequent haplotype was significantly different from other haplotype combinations (P = 0.011), the difference being more pronounced in ER-positive (P = 0.005) and progesterone receptor-positive (P = 0.008) tumors. Regression modeling identified the ER status and haplotype as the main determinants of DNA methylation variability. We identified a putative c-Myb response element (MRE) that was present in one of two minimal promoter haplotypes. In vitro analysis showed that c-Myb binds to the MRE, but binding was weakened by the two polymorphisms. Transient cotransfections in luminal-type and basal-like breast cancer cell lines confirmed cell-specific differential binding of c-Myb to the polymorphic sites, leading to a change in the expression from the GSTP1 promoter in vivo. GSTP1 expression was moderately but significantly (P = 0.01) reduced after siRNA-mediated knockdown of c-Myb. Our results indicate that haplotype structure of a promoter is important for the extent of DNA methylation.
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Affiliation(s)
- Jo Anders Rønneberg
- Department of Genetics, The Norwegian Radium Hospital, Rikshospitalet University Hospital, Montebello, Oslo, Norway
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Range R, Lapraz F, Quirin M, Marro S, Besnardeau L, Lepage T. Cis-regulatory analysis of nodal and maternal control of dorsal-ventral axis formation by Univin, a TGF-β related to Vg1. Development 2007; 134:3649-64. [PMID: 17855430 DOI: 10.1242/dev.007799] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The TGF-β family member Nodal is essential for specification of the dorsal-ventral axis of the sea urchin embryo, but the molecular factors regulating its expression are not known. Analysis of the nodalpromoter is an excellent entry point to identify these factors and to dissect the regulatory logic driving dorsal-ventral axis specification. Using phylogenetic footprinting, we delineated two regulatory regions located in the 5′ region of the nodal promoter and in the intron that are required for correct spatial expression and for autoregulation. The 5′regulatory region contains essential binding sites for homeodomain, bZIP, Oct,Tcf/Lef, Sox and Smad transcription factors, and a binding site for an unidentified spatial repressor possibly related to Myb. Soon after its initiation, nodal expression critically requires autoregulation by Nodal and signaling by the maternal TGF-β Univin. We show that Univin is related to Vg1, that both Nodal and Univin signal through Alk4/5/7, and that zygotic expression of univin, like that of nodal, is dependent on SoxB1 function and Tcf/β-catenin signaling. This work shows that Tcf, SoxB1 and Univin play essential roles in the regulation of nodal expression in the sea urchin and suggests that some of the regulatory interactions controlling nodal expression predate the chordates. The data are consistent with a model of nodal regulation in which a maternal TGF-β acts in synergy with maternal transcription factors and with spatial repressors to establish the dorsal-ventral axis of the sea urchin embryo.
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Affiliation(s)
- Ryan Range
- UMR 7009 CNRS, Université Pierre et Marie Curie (Paris 6 Observatoire Océanologique, 06230 Villefranche-sur-mer, France
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Peng S, Lalani S, Leavenworth JW, Ho IC, Pauza ME. c-Maf interacts with c-Myb to down-regulate Bcl-2 expression and increase apoptosis in peripheral CD4 cells. Eur J Immunol 2007; 37:2868-80. [PMID: 17823980 DOI: 10.1002/eji.200636979] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The transcription factor c-Maf is critical for IL-4 production and the development of Th2 cells, which promote humoral immunity and protect against extracellular parasites. Yet, little else is known of c-Maf function in CD4 cells. Here, we identify a novel role for c-Maf in regulating susceptibility to apoptosis. Overexpression of c-Maf results in increased susceptibility of CD4 cells to apoptosis induced by multiple stimuli, including growth factor withdrawal, dexamethasone, irradiation, and TCR engagement. This effect is independent of Fas or p53; however, Bcl-2 expression is reduced in c-Maf Tg CD4 cells. Immunoprecipitation and Western blot analyses demonstrate that c-Maf-c-Myb complex formation is enhanced among T cells from c-Maf Tg mice compared to non-Tg littermates following TCR engagement. Unlike non-Tg T cells, c-Myb binding to the Bcl-2 promoter is not detectable in c-Maf Tg T cells by chromatin immunoprecipitation. In reporter assays, Bcl-2 promoter activity is reduced by c-Maf in a dose-dependent manner. Furthermore, transgene-mediated Bcl-2 expression corrects the apoptosis defect observed among c-Maf Tg CD4 cells. These data suggest that c-Maf can interact with c-Myb to reduce Bcl-2 expression, thereby limiting CD4 cell survival following TCR engagement.
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Affiliation(s)
- Siying Peng
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL 62794, USA
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Kubinski K, Zielinski R, Hellman U, Mazur E, Szyszka R. Yeast elf1 factor is phosphorylated and interacts with protein kinase CK2. BMB Rep 2006; 39:311-8. [PMID: 16756761 DOI: 10.5483/bmbrep.2006.39.3.311] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One of the biggest group of proteins influenced by protein kinase CK2 is formed by factors engaged in gene expression. Here we have reported recently identified yeast transcription elongation factor Elf1 as a new substrate for both monomeric and tetrameric forms of CK2. Elf1 serves as a substrate for both the recombinant CK2alpha' (K(m) 0.38 microM) and holoenzyme (K(m) 0.13 microM). By MALDI-MS we identified the two serine residues at positions 95 and 117 as the most probable in vitro phosphorylation sites. Coimmunoprecypitation experiments show that Elf1 interacts with catalytic (alpha and alpha') as well as regulatory (beta and beta') subunits of CK2. These data may help to elucidate the role of protein kinase CK2 and Elf1 in the regulation of transcription elongation.
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Affiliation(s)
- Konrad Kubinski
- Department of Molecular Biology, Environmental Protection Institute, John Paul II Catholic University of Lublin, Poland
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Ong SJ, Hsu HM, Liu HW, Chu CH, Tai JH. Multifarious transcriptional regulation of adhesion protein gene ap65-1 by a novel Myb1 protein in the protozoan parasite Trichomonas vaginalis. EUKARYOTIC CELL 2006; 5:391-9. [PMID: 16467479 PMCID: PMC1405892 DOI: 10.1128/ec.5.2.391-399.2006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The transcription efficiency of an adhesion protein gene, ap65-1, in Trichomonas vaginalis varies with changes in the iron supply and with the growth stage. In the present study, two Myb recognition elements, MRE-1/MRE-2r and MRE-2f, were found to play antagonistic roles in regulating the iron-inducible activity of an ap65-1 reporter gene. Intriguingly, either of these elements was shown to be sufficient to repress basal activity, but together they were also shown to activate growth-related activity of the reporter gene in iron-depleted cells. A myb1 gene which encodes a 24-kDa protein containing a Myb-like R2R3 DNA binding domain was identified from Southwestern screening of MRE-2f-binding proteins. The Myb1 protein was detected as a major 35-kDa protein which exhibited variations in nuclear concentration with changes in the iron supply. A recombinant Myb1 protein was shown to differentially interact with MRE-1/MRE-2r and MRE-2f in vitro. Overexpression of hemagglutinin-tagged Myb1 in T. vaginalis resulted in repression or activation of ap65-1 transcription in iron-depleted cells at an early and a late stage of cell growth, respectively, while iron-inducible ap65-1 transcription was constitutively repressed. The hemagglutinin-tagged Myb1 protein was found to constantly occupy the chromosomal ap65-1 promoter at a proximal site, but it also selected two more distal sites only at the late growth stage. Together, these observations suggest that Myb1 critically regulates multifarious ap65-1 transcription, possibly via differential selection of multiple promoter sites upon environmental changes.
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Affiliation(s)
- Shiou-Jeng Ong
- Division of Infectious Diseases, Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
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26
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Kim KY, Lee JW, Park MS, Jung MH, Jeon GA, Nam MJ. Expression of a thioredoxin-related protein-1 is induced by prostaglandin E(2). Int J Cancer 2006; 118:1670-9. [PMID: 16231315 DOI: 10.1002/ijc.21572] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Prostaglandin E(2) (PGE(2)) plays an important role in protection of the gastric mucosa against various damaging agents and growth-inhibitory activity on tumor cells. However, the precise regulation mechanism of PGE(2) in gastric cancer cells is still unclear. In this study, we isolated a gene, which is regulated by PGE(2) in SNU-1, human gastric adenocarcinoma cells, using differential display RT-PCR (DD RT-PCR) and characterized the function of the gene induced by PGE(2). The full-length cDNA of the gene was cloned by the rapid amplification of cDNA ends method. The 1659 base pair cDNA consists of a 30-nt 5'-noncoding region, an 891-nt open reading frame and a 738-nt 3'noncoding region that includes a poly (A) signal. As a result of protein motif search, we found that it has a conserved thioredoxin-active site, Cys-Gly-Pro-Cys and a Myb-DNA binding domain repeat signature. Thus, we designated this gene product as thioredoxin-related protein-1, TRP-1. TRP-1 was expressed in a lower extent in renal, gastric and colon cancer tissues and is translated into 33 kDa protein in nuclear and cytoplasmic fractions. TRP-1 has a thioredoxin activity, which was detected using the insulin disulfide reduction assay. Another potential role of TRP-1 is repression of B-Myb activity through direct binding to B-Myb, a transcriptional factor induced at G1-S transition. Finally, TRP-1 overexpression inhibits mammalian cell proliferation and specifically predispose to G0/G1 phase arrest. In conclusion, these results imply that TRP-1 is a mammalian thioredoxin and plays as a transcriptional repressor through direct binding to the transcription factor B-Myb.
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Affiliation(s)
- Kye Young Kim
- Department of Biomedical Sciences, National Institute of Health, Seoul 122-701, Korea
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Lang G, White JR, Argent-Katwala MJG, Allinson CG, Weston K. Myb proteins regulate the expression of diverse target genes. Oncogene 2005; 24:1375-84. [PMID: 15608679 DOI: 10.1038/sj.onc.1208301] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hematopoiesis, the process by which mature blood cells arise, is controlled by multiple transcription factors, which act in stage- and lineage-specific complexes. It is a major goal to elucidate the genes regulated by these transcription factors, in order to obtain a full understanding of the process and its malignant counterpart, leukemia. Myb family transcription factors play a central role in hematopoiesis. To identify new Myb family target genes, we have used an inducible dominant-negative protein for a subtraction cloning protocol in a model cell system (FDCP-Mix) with many characteristics of normal hematopoiesis. We present here a novel group of 29 validated Myb family target genes of diverse functions.
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Affiliation(s)
- Georgina Lang
- CRUK Centre for Cell and Molecular Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
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Hofmann CS, Wang X, Sullivan CP, Toselli P, Stone PJ, McLean SE, Mecham RP, Schreiber BM, Sonenshein GE. B-Myb Represses Elastin Gene Expression in Aortic Smooth Muscle Cells. J Biol Chem 2005; 280:7694-701. [PMID: 15615710 DOI: 10.1074/jbc.m412501200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
B-Myb represses collagen gene transcription in vascular smooth muscle cells (SMCs) in vitro and in vivo. Here we sought to determine whether elastin is similarly repressed by B-Myb. Levels of tropoelastin mRNA and protein were lower in aortas and isolated SMCs of adult transgenic mice expressing the human B-myb gene, driven by the basal cytomegalovirus promoter, compared with age-matched wild type (WT) animals. However, the vessel wall architecture and levels of insoluble elastin revealed no differences. Since elastin deposition occurs early in development, microarray analysis was performed using nontransgenic mice. Aortic levels of tropoelastin mRNA were low during embryonal growth and increased substantially in neonates, whereas B-myb levels varied inversely. Tropoelastin mRNA expression in aortas of 6-day-old neonatal transgenic and WT animals was comparable. Recently, we demonstrated that cyclin A-Cdk2 prevents B-Myb-mediated repression of collagen promoter activity. Cyclin A2 levels were higher in neonatal versus adult WT or transgenic mouse aortas. Ectopic cyclin A expression reversed the ability of B-Myb to repress elastin gene promoter activity in adult SMCs. These results demonstrate for the first time that B-Myb represses SMC elastin gene expression and that cyclin A plays a role in the developmental regulation of elastin gene expression in the aorta. Furthermore, the findings provide additional insight into the mechanism of B-myb-mediated resistance to femoral artery injury.
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Affiliation(s)
- Claudia S Hofmann
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Santilli G, Schwab R, Watson R, Ebert C, Aronow BJ, Sala A. Temperature-dependent modification and activation of B-MYB: implications for cell survival. J Biol Chem 2004; 280:15628-34. [PMID: 15618219 DOI: 10.1074/jbc.m411747200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
B-MYB is a ubiquitous transcription factor with an essential role in mouse development. Because cells with a disrupted B-MYB gene cannot be obtained, it is still unknown what is the critical function(s) exerted by B-MYB in mammalian cells. In this study we have observed that reducing B-MYB expression in primary human fibroblasts by using RNA interference results in a partial block of the cells in the G(2) phase of the cell cycle and cell death. Surprisingly, suppressing B-MYB transcriptional activity with a dominant-negative molecule is without effect, suggesting that its transactivating function is not essential. Only human or murine fibroblasts exposed to high temperature are sensitized to cell death in the presence of dominant-negative B-MYB. This correlates with temperature-dependent binding of endogenous B-MYB to transcriptional regulatory elements of the stress-related gene ApoJ/clusterin. We find that regulation of ApoJ/clusterin by B-MYB is a pro-survival response to thermal stress. Thus, B-MYB is regulated by temperature to activate genes required for cell survival.
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Affiliation(s)
- Giorgia Santilli
- Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, United Kingdom
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Selective inhibition of c-Myb DNA-binding by RNA polymers. BMC BIOCHEMISTRY 2004; 5:15. [PMID: 15527501 PMCID: PMC533864 DOI: 10.1186/1471-2091-5-15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2004] [Accepted: 11/04/2004] [Indexed: 12/26/2022]
Abstract
Background The transcription factor c-Myb is expressed in hematopoietic progenitor cells and other rapidly proliferating tissues, regulating genes important for proliferation, differentiation and survival. The DNA-binding domain (DBD) of c-Myb contains three tandemly arranged imperfect repeats, designated Myb domain R1, R2 and R3. The three-dimensional structure of the DBD shows that only the second and third Myb domains are directly involved in sequence-specific DNA-binding, while the R1 repeat does not contact DNA and only marginally affects DNA-binding properties. No structural information is available on the N-terminal 30 residues. Since deletion of the N-terminal region including R1 plays an important role in oncogenic activation of c-Myb, we asked whether this region confers properties beyond DNA-binding to the neighbouring c-Myb DBD. Results Analysis of a putative RNA-binding function of c-Myb DBD revealed that poly(G) preferentially inhibited c-Myb DNA-binding. A strong sequence-selectivity was observed when different RNA polymers were compared. Most interesting, the poly(G) sensitivity was significantly larger for a protein containing the N-terminus and the R1-repeat than for the minimal DNA-binding domain. Conclusion Preferential inhibition of c-Myb DNA binding by poly(G) RNA suggests that c-Myb is able to interact with RNA in a sequence-selective manner. While R2 and R3, but not R1, are necessary for DNA-binding, R1 seems to have a distinct role in enhancing the RNA-sensitivity of c-Myb.
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Kojima N, Inoue K, Nakajima-Shibata R, Kawahara SI, Ohtsuka E. A new, but old, nucleoside analog: the first synthesis of 1-deaza-2'-deoxyguanosine and its properties as a nucleoside and as oligodeoxynucleotides. Nucleic Acids Res 2004; 31:7175-88. [PMID: 14654693 PMCID: PMC291881 DOI: 10.1093/nar/gkh154] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The first synthesis of 5-amino-3-(2'-deoxy-beta-D-ribofuranosyl)imidazo[4,5-b]pyridin-7-one (1-deaza-2'-deoxyguanosine) is described. The compound was converted from the known AICA-deoxyriboside. The tautomeric structure of the base moiety was determined by theoretical calculation to be a hydroxyl form. Although the analog was found to be labile to acidic conditions, 1-deaza-2'-deoxyguanosine was successfully converted into a phosphoramidite derivative, which was incorporated into oligodeoxynucleotides by the standard phosphoramidite method. Thermal stabilities of oligodeoxynucleotides containing 1-deaza-2'-deoxyguanosine were investigated by thermal denaturing experiments. Also, a triphosphate analog of 1-deaza-2'-deoxyguanosine was synthesized for polymerase extension reactions. Single nucleotide insertion reactions using a template containing 1-deaza-2'-deoxyguanosine, as well as 1-deaza-2'-deoxyguanosine triphosphate, were performed using the Klenow fragment (exonuclease minus) polymerase and other polymerases. No hydrogen bonded base pairs, even a 1-deaza-2'-deoxyguanosine:cytidine base pair, were indicated by thermal denaturing studies. However, though less selective and less effective than the natural guanosine counterpart, the polymerase extension reactions suggested the formation of a base pair of 1-deaza-2'-deoxyguanosine with cytidine during the insertion reactions.
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Affiliation(s)
- Naoshi Kojima
- Institute for Biological Resources and Functions, Sapporo, Japan.
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Abstract
CK2 (formerly termed "casein kinase 2") is a ubiquitous, highly pleiotropic and constitutively active Ser/Thr protein kinase whose implication in neoplasia, cell survival, and virus infection is supported by an increasing number of arguments. Here an updated inventory of 307 CK2 protein substrates is presented. More than one-third of these are implicated in gene expression and protein synthesis as being either transcriptional factors (60) or effectors of DNA/RNA structure (50) or translational elements. Also numerous are signaling proteins and proteins of viral origin or essential to virus life cycle. In comparison, only a minority of CK2 targets (a dozen or so) are classical metabolic enzymes. An analysis of 308 sites phosphorylated by CK2 highlights the paramount relevance of negatively charged side chains that are (by far) predominant over any other residues at positions n+3 (the most crucial one), n+1, and n+2. Based on this signature, it is predictable that proteins phosphorylated by CK2 are much more numerous than those identified to date, and it is possible that CK2 alone contributes to the generation of the eukaryotic phosphoproteome more so than any other individual protein kinase. The possibility that CK2 phosphosites play some global role, e.g., by destabilizing alpha helices, counteracting caspase cleavage, and generating adhesive motifs, will be discussed.
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Affiliation(s)
- Flavio Meggio
- Dipartimento di Chimica Biologica and Istituto di Neuroscienze del CNR, Università di Padova and Venetian Institute for Molecular Medicine (VIMM), Padova, Italy
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Andersson KB, Kowenz-Leutz E, Brendeford EM, Tygsett AHH, Leutz A, Gabrielsen OS. Phosphorylation-dependent down-regulation of c-Myb DNA binding is abrogated by a point mutation in the v-myb oncogene. J Biol Chem 2003; 278:3816-24. [PMID: 12456674 DOI: 10.1074/jbc.m209404200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The viral Myb (v-Myb) oncoprotein of the avian myeloblastosis virus (AMV) is an activated form of the cellular transcription factor c-Myb causing acute monoblastic leukemia in chicken. Oncogenic v-Myb alterations include N- and C-terminal deletions as well as point mutations. Whereas truncations in Myb cause loss of various protein modifications, none of the point mutations in v-Myb has been directly linked to protein modifications. Here we show that the DNA-binding domain of c-Myb can be phosphorylated on serine 116 by the catalytic subunit of protein kinase A. Phosphorylation of Ser(116) differentially destabilizes a subtype of c-Myb-DNA complexes. The V117D mutation of the AMV v-Myb oncoprotein abolishes phosphorylation of the adjacent Ser(116) residue. Modification of Ser(116) was also detected in live cells in c-Myb, but not in AMV v-Myb. Phosphorylation-mimicking mutants of c-Myb failed to activate the resident mim-1 gene. Our data imply that protein kinase A or a kinase with similar specificity negatively regulates c-Myb function, including collaboration with C/EBP, and that the leukemogenic AMV v-Myb version evades inactivation by a point mutation that abolishes a phosphoacceptor consensus site. This suggests a novel link between Myb, a signal transduction pathway, cooperativity with C/EBP, and a point mutation in the myb oncogene.
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