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Pal S, Biswas D. Promoter-proximal regulation of gene transcription: Key factors involved and emerging role of general transcription factors in assisting productive elongation. Gene 2023:147571. [PMID: 37331491 DOI: 10.1016/j.gene.2023.147571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 06/02/2023] [Accepted: 06/13/2023] [Indexed: 06/20/2023]
Abstract
The pausing of RNA polymerase II (Pol II) at the promoter-proximal sites is a key rate-limiting step in gene expression. Cells have dedicated a specific set of proteins that sequentially establish pause and then release the Pol II from promoter-proximal sites. A well-controlled pausing and subsequent release of Pol II is crucial for thefine tuning of expression of genes including signal-responsive and developmentally-regulated ones. The release of paused Pol II broadly involves its transition from initiation to elongation. In this review article, we will discuss the phenomenon of Pol II pausing, the underlying mechanism, and also the role of different known factors, with an emphasis on general transcription factors, involved in this overall regulation. We will further discuss some recent findings suggesting a possible role (underexplored) of initiation factors in assisting the transition of transcriptionally-engaged paused Pol II into productive elongation.
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Affiliation(s)
- Sujay Pal
- Laboratory of Transcription Biology, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Kolkata - 32, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Debabrata Biswas
- Laboratory of Transcription Biology, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Kolkata - 32, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
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Liu W, Lin S, Li L, Tai Z, Liu JX. Zebrafish ELL-associated factors Eaf1/2 modulate erythropoiesis via regulating gata1a expression and WNT signaling to facilitate hypoxia tolerance. CELL REGENERATION (LONDON, ENGLAND) 2023; 12:10. [PMID: 37002435 PMCID: PMC10066051 DOI: 10.1186/s13619-022-00154-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 11/28/2022] [Indexed: 04/04/2023]
Abstract
EAF1 and EAF2, the eleven-nineteen lysine-rich leukemia (ELL)-associated factors which can assemble to the super elongation complex (AFF1/4, AF9/ENL, ELL, and P-TEFb), are reported to participate in RNA polymerase II to actively regulate a variety of biological processes, including leukemia and embryogenesis, but whether and how EAF1/2 function in hematopoietic system related hypoxia tolerance during embryogenesis remains unclear. Here, we unveiled that deletion of EAF1/2 (eaf1-/- and eaf2-/-) caused reduction in hypoxia tolerance in zebrafish, leading to reduced erythropoiesis during hematopoietic processes. Meanwhile, eaf1-/- and eaf2-/- mutants showed significant reduction in the expression of key transcriptional regulators scl, lmo2, and gata1a in erythropoiesis at both 24 h post fertilization (hpf) and 72 hpf, with gata1a downregulated while scl and lmo2 upregulated at 14 hpf. Mechanistically, eaf1-/- and eaf2-/- mutants exhibited significant changes in the expression of epigenetic modified histones, with a significant increase in the binding enrichment of modified histone H3K27me3 in gata1a promoter rather than scl and lmo2 promoters. Additionally, eaf1-/- and eaf2-/- mutants exhibited a dynamic expression of canonical WNT/β-catenin signaling during erythropoiesis, with significant reduction in p-β-Catenin level and in the binding enrichment of both scl and lmo2 promoters with the WNT transcriptional factor TCF4 at 24 hpf. These findings demonstrate an important role of Eaf1/2 in erythropoiesis in zebrafish and may have shed some light on regeneration medicine for anemia and related diseases and on molecular basis for fish economic or productive traits, such as growth, disease resistance, hypoxia tolerance, and so on.
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Affiliation(s)
- WenYe Liu
- grid.35155.370000 0004 1790 4137College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, 430070 Wuhan, China
| | - ShuHui Lin
- grid.35155.370000 0004 1790 4137College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, 430070 Wuhan, China
| | - LingYa Li
- grid.35155.370000 0004 1790 4137College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, 430070 Wuhan, China
| | - ZhiPeng Tai
- grid.35155.370000 0004 1790 4137College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, 430070 Wuhan, China
| | - Jing-Xia Liu
- grid.35155.370000 0004 1790 4137College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, 430070 Wuhan, China
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Zha J, Zhong M, Pan G, Chen Q, Jiang Y, Lai Q, Tan J, Zhou H, Wu H, Xu B. Stratification and therapeutic potential of ELL in cytogenetic normal acute myeloid leukemia. Gene 2023; 856:147110. [PMID: 36543308 DOI: 10.1016/j.gene.2022.147110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 11/25/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022]
Abstract
Optimizing prognostic stratification of patients with cytogenetic normal acute myeloid leukemia (CN-AML), a highly heterogeneous subgroup in AML, appears to be important to improve its treatment and clinical outcome. Here, we report a potential role of ELL, a gene associated with leukemogenesis in AML, in prognostic stratification of CN-AML patients. By analyzing public available databases, we found that ELL was highly expressed in AML patients compared with healthy donors. Kaplan-Meier analysis revealed that ELL expression markedly correlated with short overall survival (OS) of CN-AML patients. In COX multivariable regression analysis, higher ELL expression was an independent prognostic factor for OS in CN-AML. Knockdown of ELL by shRNAs sensitized KG-1α cells to anti-leukemic agents such as idarubicin (IDA) and chidamide (CS055), supporting its role in therapeutic response and outcome in AML. To understand its function in CN-AML, we further analyzed the ELL-driving gene signature. ELL-related genes were particularly enriched in cell adhesion molecules, cell differentiation, pathways in cancer, sequence-specific DNA binding, and extracellular matrix (ECM)-receptor interaction. Analysis of the PPI network identified 25 hub genes, including the stem cell gene BMP4. While BMP4 expression was significantly associated with ELL in CN-AML, knockdown of ELL markedly down-regulated BMP4 expression, suggesting that ELL might function via regulating BMP4 in AML. Together, these observations suggest a novel mechanism underlying pro-leukemogenic role of ELL via BMP4 up-regulation in AML and its potential value to serve as a predictive biomarker for therapeutic response and outcome of CN-AML patients.
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Affiliation(s)
- Jie Zha
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China; Key Laboratory of Xiamen for Diagnosis and Treatment of Hematological Malignancy, Xiamen 361003, China
| | - Mengya Zhong
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China; Key Laboratory of Xiamen for Diagnosis and Treatment of Hematological Malignancy, Xiamen 361003, China
| | - Guangchao Pan
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China; Key Laboratory of Xiamen for Diagnosis and Treatment of Hematological Malignancy, Xiamen 361003, China
| | - Qinwei Chen
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China; Key Laboratory of Xiamen for Diagnosis and Treatment of Hematological Malignancy, Xiamen 361003, China
| | - Yuelong Jiang
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China; Key Laboratory of Xiamen for Diagnosis and Treatment of Hematological Malignancy, Xiamen 361003, China
| | - Qian Lai
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China; Key Laboratory of Xiamen for Diagnosis and Treatment of Hematological Malignancy, Xiamen 361003, China
| | - Jinshui Tan
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China; Key Laboratory of Xiamen for Diagnosis and Treatment of Hematological Malignancy, Xiamen 361003, China
| | - Hui Zhou
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China; Key Laboratory of Xiamen for Diagnosis and Treatment of Hematological Malignancy, Xiamen 361003, China
| | - Hua Wu
- Department of Nuclear Medicine, the First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China.
| | - Bing Xu
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen University, Xiamen 361003, China; Key Laboratory of Xiamen for Diagnosis and Treatment of Hematological Malignancy, Xiamen 361003, China.
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Negative Feedback Loop Mechanism between EAF1/2 and DBC1 in Regulating ELL Stability and Functions. Mol Cell Biol 2022; 42:e0015122. [PMID: 36036574 PMCID: PMC9590304 DOI: 10.1128/mcb.00151-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Although ELL-associated factors 1 and 2 (EAF1/2) have been shown to enhance RNA polymerase II-mediated transcription in vitro, their functional roles in vivo are poorly known. In this report, we show functions of these proteins in regulating ELL stability through their competitive binding with HDAC3 at the N terminus of ELL. Reduced HDAC3 binding to ELL causes increased acetylation leading to reduced ubiquitylation-mediated degradation. Similar functional roles played by DBC1 in regulating ELL stability further prompted in-depth analyses that demonstrated presence of negative feedback loop mechanisms between DBC1 and EAF1/2 in maintaining overall ELL level. Mechanistically, increased DBC1 reduces EAF1/2 level through increased ubiquitylation involving E3 ubiquitin ligase TRIM28, whereas increased EAF1/2 reduces DBC1 level through reduced transcription. Physiologically, after a few passages, ELL levels in either DBC1 or EAF1 knockdown cells are restored through enhanced expression of EAF1 and DBC1, respectively. Interestingly, for maintenance of ELL level, mammalian cells prefer the EAF1-dependent pathway during exposure to genotoxic stress, and the DBC1-dependent pathway during exposure to growth factors. Thus, we describe coordinated functions of multiple factors, including EAF1/2, HDAC3, DBC1, and TRIM28 in regulating ELL protein level for optimal target gene expression in a context-dependent manner within mammalian cells.
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Saito AC, Endo C, Fukazawa Y, Higashi T, Chiba H. Effects of TAMP family on the tight junction strand network and barrier function in epithelial cells. Ann N Y Acad Sci 2022; 1517:234-250. [PMID: 36069127 DOI: 10.1111/nyas.14889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Occludin, tricellulin, and marvelD3 belong to the tight junction (TJ)-associated MARVEL protein family. Occludin and tricellulin jointly contribute to TJ strand branching point formation and epithelial barrier maintenance. However, whether marvelD3 has the same function remains unclear. Furthermore, the roles of the carboxy-terminal cytoplasmic tail, which is conserved in occludin and tricellulin, on the regulation of TJ strand morphology have not yet been explored in epithelial cells. We established tricellulin/occludin/marveld3 triple-gene knockout (tKO) MDCK II cells and evaluated the roles of marvelD3 in the TJ strand structure and barrier function using MDCK II cells and a mathematical model. The complexity of TJ strand networks and paracellular barrier did not change in tKO cells compared to that in tricellulin/occludin double-gene knockout (dKO) cells. Exogenous marvelD3 expression in dKO cells did not increase the complexity of TJ strand networks and epithelial barrier tightness. The expression of the carboxy-terminal truncation mutant of tricellulin restored the barrier function in the dKO cells, whereas occludin lacking the carboxy-terminal cytoplasmic tail was not expressed on the plasma membrane. These data suggest that marvelD3 does not affect the morphology of TJ strands and barrier function in MDCK II cells and that the carboxy-terminal cytoplasmic tail of tricellulin is dispensable for barrier improvement.
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Affiliation(s)
- Akira C Saito
- Department of Basic Pathology, Fukushima Medical University, Fukushima, Japan
| | - Chisato Endo
- Department of Basic Pathology, Fukushima Medical University, Fukushima, Japan
| | - Yugo Fukazawa
- Division of Brain Structure and Function, Faculty of Medical Science, Life Science Innovation Center, University of Fukui, Fukui, Japan
| | - Tomohito Higashi
- Department of Basic Pathology, Fukushima Medical University, Fukushima, Japan
| | - Hideki Chiba
- Department of Basic Pathology, Fukushima Medical University, Fukushima, Japan
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Sequence, structural and functional conservation among the human and fission yeast ELL and EAF transcription elongation factors. Mol Biol Rep 2021; 49:1303-1320. [PMID: 34807377 DOI: 10.1007/s11033-021-06958-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 11/11/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Transcription elongation is a dynamic and tightly regulated step of gene expression in eukaryotic cells. Eleven nineteen Lysine rich Leukemia (ELL) and ELL Associated Factors (EAF) family of conserved proteins are required for efficient RNA polymerase II-mediated transcription elongation. Orthologs of these proteins have been identified in different organisms, including fission yeast and humans. METHODS AND RESULTS In the present study, we have examined the sequence, structural and functional conservation between the fission yeast and human ELL and EAF orthologs. Our computational analysis revealed that these proteins share some sequence characteristics, and were predominantly disordered in both organisms. Our functional complementation assays revealed that both human ELL and EAF proteins could complement the lack of ell1+ or eaf1+ in Schizosaccharomyces pombe respectively. Furthermore, our domain mapping experiments demonstrated that both the amino and carboxyl terminal domains of human EAF proteins could functionally complement the S. pombe eaf1 deletion phenotypes. However, only the carboxyl-terminus domain of human ELL was able to partially rescue the phenotypes associated with lack of ell1+ in S. pombe. CONCLUSIONS Collectively, our work adds ELL-EAF to the increasing list of human-yeast complementation gene pairs, wherein the simpler fission yeast can be used to further enhance our understanding of the role of these proteins in transcription elongation and human disease.
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Takahashi S, Kanai A, Okuda H, Miyamoto R, Komata Y, Kawamura T, Matsui H, Inaba T, Takaori-Kondo A, Yokoyama A. HBO1-MLL interaction promotes AF4/ENL/P-TEFb-mediated leukemogenesis. eLife 2021; 10:e65872. [PMID: 34431785 PMCID: PMC8387021 DOI: 10.7554/elife.65872] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 08/12/2021] [Indexed: 12/27/2022] Open
Abstract
Leukemic oncoproteins cause uncontrolled self-renewal of hematopoietic progenitors by aberrant gene activation, eventually causing leukemia. However, the molecular mechanism underlying aberrant gene activation remains elusive. Here, we showed that leukemic MLL fusion proteins associate with the HBO1 histone acetyltransferase (HAT) complex through their trithorax homology domain 2 (THD2) in various human cell lines. MLL proteins associated with the HBO1 complex through multiple contacts mediated mainly by the ING4/5 and PHF16 subunits in a chromatin-bound context where histone H3 lysine 4 tri-methylation marks were present. Of the many MLL fusions, MLL-ELL particularly depended on the THD2-mediated association with the HBO1 complex for leukemic transformation. The C-terminal portion of ELL provided a binding platform for multiple factors including AF4, EAF1, and p53. MLL-ELL activated gene expression in murine hematopoietic progenitors by loading an AF4/ENL/P-TEFb (AEP) complex onto the target promoters wherein the HBO1 complex promoted the association with AEP complex over EAF1 and p53. Moreover, the NUP98-HBO1 fusion protein exerted its oncogenic properties via interaction with MLL but not its intrinsic HAT activity. Thus, the interaction between the HBO1 complex and MLL is an important nexus in leukemic transformation, which may serve as a therapeutic target for drug development.
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Affiliation(s)
- Satoshi Takahashi
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
- Department of Hematology and Oncology, Kyoto University Graduate School of MedicineKyotoJapan
| | - Akinori Kanai
- Department of Molecular Oncology and Leukemia Program Project, Research Institute for Radiation Biology and Medicine, Hiroshima UniversityHiroshimaJapan
| | - Hiroshi Okuda
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
| | - Ryo Miyamoto
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
| | - Yosuke Komata
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
| | | | - Hirotaka Matsui
- Department of Molecular Laboratory Medicine, Faculty of Life Sciences, Kumamoto UniversityKumamotoJapan
| | - Toshiya Inaba
- Department of Molecular Oncology and Leukemia Program Project, Research Institute for Radiation Biology and Medicine, Hiroshima UniversityHiroshimaJapan
| | - Akifumi Takaori-Kondo
- Department of Hematology and Oncology, Kyoto University Graduate School of MedicineKyotoJapan
| | - Akihiko Yokoyama
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
- Department of Hematology and Oncology, Kyoto University Graduate School of MedicineKyotoJapan
- Division of Hematological Malignancy, National Cancer Center Research InstituteTokyoJapan
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Yokoyama A. Leukemogenesis via aberrant self-renewal by the MLL/AEP-mediated transcriptional activation system. Cancer Sci 2021; 112:3935-3944. [PMID: 34251718 PMCID: PMC8486200 DOI: 10.1111/cas.15054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 07/04/2021] [Accepted: 07/09/2021] [Indexed: 12/17/2022] Open
Abstract
Homeostasis of the hematopoietic system is achieved in a hierarchy, with hematopoietic stem cells at the pinnacle. Because only hematopoietic stem cells (HSCs) can self-renew, the size of the hematopoietic system is strictly controlled. In hematopoietic reconstitution experiments, 1 HSC can reconstitute the entire hematopoietic system, whereas 50 multipotent progenitors cannot. This indicates that only HSCs self-renew, whereas non-HSC hematopoietic progenitors are programmed to differentiate or senesce. Oncogenic mutations of the mixed lineage leukemia gene (MLL) overcome this "programmed differentiation" by conferring the self-renewing ability to non-HSC hematopoietic progenitors. In leukemia, mutated MLL proteins constitutively activate a broad range of previously transcribed CpG-rich promoters by an MLL-mediated transcriptional activation system. This system promotes self-renewal by replicating an expression profile similar to that of the mother cell in its daughter cells. In this transcriptional activation system, MLL binds to unmethylated CpG-rich promoters and recruits RNA polymerase II. MLL recruits p300/CBP through its transcriptional activation domain, which acetylates histone H3 at lysines 9, 18, and 27. The AF4 family/ENL family/P-TEFb complex (AEP) binds to acetylated H3K9/18/27 to activate transcription. Gene rearrangements of MLL with AEP- or CBP/p300-complex components generate constitutively active transcriptional machinery of this transcriptional activation system, which causes aberrant self-renewal of leukemia stem cells. Inhibitors of the components of this system effectively decrease their leukemogenic potential.
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Affiliation(s)
- Akihiko Yokoyama
- Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Japan.,National Cancer Center Research Institute, Tokyo, Japan
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Panagopoulos I, Andersen K, Eilert-Olsen M, Rognlien AG, Munthe-Kaas MC, Micci F, Heim S. Rare KMT2A-ELL and Novel ZNF56-KMT2A Fusion Genes in Pediatric T-cell Acute Lymphoblastic Leukemia. Cancer Genomics Proteomics 2021; 18:121-131. [PMID: 33608309 DOI: 10.21873/cgp.20247] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/20/2021] [Accepted: 01/25/2021] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND/AIM Previous reports have associated the KMT2A-ELL fusion gene, generated by t(11;19)(q23;p13.1), with acute myeloid leukemia (AML). We herein report a KMT2A-ELL and a novel ZNF56-KMT2A fusion genes in a pediatric T-lineage acute lymphoblastic leukemia (T-ALL). MATERIALS AND METHODS Genetic investigations were performed on bone marrow of a 13-year-old boy diagnosed with T-ALL. RESULTS A KMT2A-ELL and a novel ZNF56-KMT2A fusion genes were generated on der(11)t(11;19)(q23;p13.1) and der(19)t(11;19)(q23;p13.1), respectively. Exon 20 of KMT2A fused to exon 2 of ELL in KMT2A-ELL chimeric transcript whereas exon 1 of ZNF56 fused to exon 21 of KMT2A in ZNF56-KMT2A transcript. A literature search revealed four more T-ALL patients carrying a KMT2A-ELL fusion. All of them were males aged 11, 11, 17, and 20 years. CONCLUSION KMT2A-ELL fusion is a rare recurrent genetic event in T-ALL with uncertain prognostic implications. The frequency and impact of ZNF56-KMT2A in T-ALL are unknown.
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Affiliation(s)
- Ioannis Panagopoulos
- Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway;
| | - Kristin Andersen
- Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Martine Eilert-Olsen
- Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Anne Gro Rognlien
- Department of Pediatric Hematology and Oncology, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Monica Cheng Munthe-Kaas
- Department of Pediatric Hematology and Oncology, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Francesca Micci
- Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Sverre Heim
- Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
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Basu S, Nandy A, Biswas D. Keeping RNA polymerase II on the run: Functions of MLL fusion partners in transcriptional regulation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194563. [PMID: 32348849 DOI: 10.1016/j.bbagrm.2020.194563] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/13/2020] [Accepted: 04/13/2020] [Indexed: 12/21/2022]
Abstract
Since the identification of key MLL fusion partners as transcription elongation factors regulating expression of HOX cluster genes during hematopoiesis, extensive work from the last decade has resulted in significant progress in our overall mechanistic understanding of role of MLL fusion partner proteins in transcriptional regulation of diverse set of genes beyond just the HOX cluster. In this review, we are going to detail overall understanding of role of MLL fusion partner proteins in transcriptional regulation and thus provide mechanistic insights into possible MLL fusion protein-mediated transcriptional misregulation leading to aberrant hematopoiesis and leukemogenesis.
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Affiliation(s)
- Subham Basu
- Laboratory of Transcription Biology, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Kolkata 32, India
| | - Arijit Nandy
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Debabrata Biswas
- Laboratory of Transcription Biology, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Kolkata 32, India.
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Takahashi S, Yokoyama A. The molecular functions of common and atypical MLL fusion protein complexes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194548. [PMID: 32320750 DOI: 10.1016/j.bbagrm.2020.194548] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/19/2020] [Accepted: 03/31/2020] [Indexed: 12/17/2022]
Abstract
Mixed-lineage leukemia (MLL) fuses with a variety of partners to produce a functionally altered MLL complex that is not expressed in normal cells, which transforms normal hematopoietic progenitors into leukemia cells. Because more than 80 fusion partners have been identified to date, the molecular functions of MLL fusion protein complexes appear diverse. However, over the past decade, the common functions utilized for leukemic transformation have begun to be elucidated. It appears that most (if not all) MLL fusion protein complexes utilize the AF4/ENL/P-TEFb and DOT1L complexes to some extent. Based on an understanding of the underlying molecular mechanisms, several molecular targeting drugs are being developed, opening paths to novel therapies. Here, we review the recent progress made in identifying the molecular functions of various MLL fusions and categorize the numerous fusion partners into several functionally-distinct groups to help discern commonalities and differences among various MLL fusion protein complexes.
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Affiliation(s)
- Satoshi Takahashi
- Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Japan; Department of Hematology and Oncology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Akihiko Yokoyama
- Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Japan; National Cancer Center Research Institute, Tokyo, Japan.
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12
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Schwaller J. Learning from mouse models of MLL fusion gene-driven acute leukemia. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194550. [PMID: 32320749 DOI: 10.1016/j.bbagrm.2020.194550] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/17/2020] [Accepted: 04/05/2020] [Indexed: 01/28/2023]
Abstract
5-10% of human acute leukemias carry chromosomal translocations involving the mixed lineage leukemia (MLL) gene that result in the expression of chimeric protein fusing MLL to >80 different partners of which AF4, ENL and AF9 are the most prevalent. In contrast to many other leukemia-associated mutations, several MLL-fusions are powerful oncogenes that transform hematopoietic stem cells but also more committed progenitor cells. Here, I review different approaches that were used to express MLL fusions in the murine hematopoietic system which often, but not always, resulted in highly penetrant and transplantable leukemias that closely phenocopied the human disease. Due to its simple and reliable nature, reconstitution of irradiated mice with bone marrow cells retrovirally expressing the MLL-AF9 fusion became the most frequently in vivo model to study the biology of acute myeloid leukemia (AML). I review some of the most influential studies that used this model to dissect critical protein interactions, the impact of epigenetic regulators, microRNAs and microenvironment-dependent signals for MLL fusion-driven leukemia. In addition, I highlight studies that used this model for shRNA- or genome editing-based screens for cellular vulnerabilities that allowed to identify novel therapeutic targets of which some entered clinical trials. Finally, I discuss some inherent characteristics of the widely used mouse model based on retroviral expression of the MLL-AF9 fusion that can limit general conclusions for the biology of AML. This article is part of a Special Issue entitled: The MLL family of proteins in normal development and disease edited by Thomas A Milne.
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Affiliation(s)
- Juerg Schwaller
- University Children's Hospital Beider Basel (UKBB), Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland.
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13
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Multivalent Role of Human TFIID in Recruiting Elongation Components at the Promoter-Proximal Region for Transcriptional Control. Cell Rep 2020; 26:1303-1317.e7. [PMID: 30699356 DOI: 10.1016/j.celrep.2019.01.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 12/05/2018] [Accepted: 01/02/2019] [Indexed: 01/08/2023] Open
Abstract
Despite substantial progress in our understanding of the players involved and the regulatory mechanisms controlling the initiation and elongation steps of transcription, little is known about the recruitment of elongation factors at promoter-proximal regions for the initiation-to-elongation transition. Here, we show evidence that human TFIID, which initiates pre-initiation complex (PIC) assembly, contributes to regulating the recruitment of super-elongation complex (SEC) components at the promoter-proximal region through interactions among selective TAF and SEC components. In vitro direct interactions, coupled with cell-based assays, identified an important poly-Ser domain within SEC components that are involved in their interaction with TFIID. DNA template-based recruitment assays, using purified components, further show a direct role for poly-Ser domain-dependent TFIID interaction in recruiting SEC components on target DNA. Consistently, ChIP and RNA analyses have shown the importance of this mechanism in TFIID-dependent SEC recruitment and target gene expression within mammalian cells.
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14
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Capela de Matos RR, Ney Garcia DR, Othman MAK, Moura Ferreira G, Melo JB, Carreira IM, Meyer C, Marschalek R, Costa ES, Land MGP, Liehr T, Ribeiro RC, Silva MLM. A New Complex Karyotype Involving a KMT2A-r Variant Three-Way Translocation in a Rare Clinical Presentation of a Pediatric Patient with Acute Myeloid Leukemia. Cytogenet Genome Res 2019; 157:213-219. [PMID: 30974445 DOI: 10.1159/000499640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2018] [Indexed: 11/19/2022] Open
Abstract
Patients with childhood acute myeloid leukemia (AML) with complex karyotypes (CKs) have a dismal outcome. However, for patients with a KMT2A rearrangement (KMT2A-r), the prognosis appears to depend on the fusion partner gene rather than the karyotype structure. Thus, a precise characterization of KMT2A-r and the fusion partner genes, especially in CKs, is of interest for managing AML. We describe the clinical and molecular features of a child who presented with a large abdominal mass, AML, and a new CK, involving chromosomes 11, 16, and 19 leading to a KMT2A-MLLT1 fusion and 2 extra copies of the ELL gene, thus resulting in the concurrent overexpression of MLLT1 and ELL. Molecular cytogenetic studies defined the karyotype as 47,XY,der(11)t(11;16)(q23.3;p11.2),der(16)t(16;19)(p11.2;p13.3),der(19)t(11;19)(q23.3;p13.3),+der(19)t(16;19)(16pter→p11.2::19p13.3→19q11::19p11→19p13.3::16p11.2→16pter). Array CGH revealed a gain of 30.5 Mb in the 16p13.3p11.2 region and a gain of 18.1 Mb in the 19p13.3p12 region. LDI-PCR demonstrated the KMT2A-MLLT1 fusion. Reverse sequence analysis showed that the MLLT1 gene was fused to the 16p11.2 region. RT-qPCR quantification revealed that ELL and MLLT1 were overexpressed (4- and 10-fold, respectively). In summary, this is a pediatric case of AML presenting a novel complex t(11;16;19) variant with overexpression of ELL and MLLT1.
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MESH Headings
- Child
- Chromosomes, Human, Pair 11/genetics
- Chromosomes, Human, Pair 16/genetics
- Chromosomes, Human, Pair 19/genetics
- Histone-Lysine N-Methyltransferase/genetics
- Humans
- Karyotype
- Leukemia, Myeloid, Acute/genetics
- Male
- Myeloid-Lymphoid Leukemia Protein/genetics
- Neoplasm Proteins/genetics
- Nuclear Proteins/genetics
- Oncogene Proteins, Fusion/genetics
- Transcription Factors/genetics
- Transcriptional Elongation Factors/genetics
- Translocation, Genetic
- Up-Regulation
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15
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Yokoyama A. RNA Polymerase II-Dependent Transcription Initiated by Selectivity Factor 1: A Central Mechanism Used by MLL Fusion Proteins in Leukemic Transformation. Front Genet 2019; 9:722. [PMID: 30693017 PMCID: PMC6339877 DOI: 10.3389/fgene.2018.00722] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 12/21/2018] [Indexed: 11/13/2022] Open
Abstract
Cancer cells transcribe RNAs in a characteristic manner in order to maintain their oncogenic potentials. In eukaryotes, RNA is polymerized by three distinct RNA polymerases, RNA polymerase I, II, and III (RNAP1, RNAP2, and RNAP3, respectively). The transcriptional machinery that initiates each transcription reaction has been purified and characterized. Selectivity factor 1 (SL1) is the complex responsible for RNAP1 pre-initiation complex formation. However, whether it plays any role in RNAP2-dependent transcription remains unclear. Our group previously found that SL1 specifically associates with AF4 family proteins. AF4 family proteins form the AEP complex with ENL family proteins and the P-TEFb elongation factor. Similar complexes have been independently characterized by several different laboratories and are often referred to as super elongation complex. The involvement of AEP in RNAP2-dependent transcription indicates that SL1 must play an important role in RNAP2-dependent transcription. To date, this role of SL1 has not been appreciated. In leukemia, AF4 and ENL family genes are frequently rearranged to form chimeric fusion genes with MLL. The resultant MLL fusion genes produce chimeric MLL fusion proteins comprising MLL and AEP components. The MLL portion functions as a targeting module, which specifically binds chromatin containing di-/tri-methylated histone H3 lysine 36 and non-methylated CpGs. This type of chromatin is enriched at the promoters of transcriptionally active genes which allows MLL fusion proteins to selectively bind to transcriptionally-active/CpG-rich gene promoters. The fusion partner portion, which recruits other AEP components and SL1, is responsible for activation of RNAP2-dependent transcription. Consequently, MLL fusion proteins constitutively activate the transcription of previously-transcribed MLL target genes. Structure/function analysis has shown that the ability of MLL fusion proteins to transform hematopoietic progenitors depends on the recruitment of AEP and SL1. Thus, the AEP/SL1-mediated gene activation pathway appears to be the central mechanism of MLL fusion-mediated transcriptional activation. However, the molecular mechanism by which SL1 activates RNAP2-dependent transcription remains largely unclear. This review aims to cover recent discoveries of the mechanism of transcriptional activation by MLL fusion proteins and to introduce novel roles of SL1 in RNAP2-dependent transcription by discussing how the RNAP1 machinery may be involved in RNAP2-dependent gene regulation.
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Affiliation(s)
- Akihiko Yokoyama
- Tsuruoka Meatabolomics Laboratory, National Cancer Center, Yamagata, Japan
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16
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Sweta K, Dabas P, Jain K, Sharma N. The amino-terminal domain of ELL transcription elongation factor is essential for ELL function in Schizosaccharomyces pombe. MICROBIOLOGY-SGM 2017; 163:1641-1653. [PMID: 29043956 DOI: 10.1099/mic.0.000554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Transcriptional elongation is a critical step for regulating expression of protein-coding genes. Multiple transcription elongation factors have been identified in vitro, but the physiological roles of many of them are still not clearly understood. The ELL (Eleven nineteen Lysine rich Leukemia) family of transcription elongation factors are conserved from fission yeast to humans. Schizosaccharomyces pombe contains a single ELL homolog (SpELL) that is not essential for its survival. Therefore to gain insights into the in vivo cellular functions of SpELL, we identified phenotypes associated with deletion of ell1 in S. pombe. Our results demonstrate that SpELL is required for normal growth of S. pombe cells. Furthermore, cells lacking ell1+ exhibit a decrease in survival when exposed to DNA-damaging conditions, but their growth is not affected under environmental stress conditions. ELL orthologs in different organisms contain three conserved domains, an amino-terminal domain, a middle domain and a carboxyl-terminal domain. We also carried out an in vivo functional mapping of these conserved domains within S. pombe ELL and uncovered a critical role for its amino-terminus in regulating all its cellular functions, including growth under different conditions, transcriptional elongation potential and interaction with S. pombe EAF. Taken together our results suggest that the domain organization of ELL proteins is conserved across species, but the in vivo functions as well as the relationship between the various domains and roles of ELL show species-specific differences.
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Affiliation(s)
- Kumari Sweta
- University School of Biotechnology, G.G.S. Indraprastha University, Sector16C, Dwarka, New Delhi-110078, India
| | - Preeti Dabas
- University School of Biotechnology, G.G.S. Indraprastha University, Sector16C, Dwarka, New Delhi-110078, India
| | - Kamal Jain
- University School of Biotechnology, G.G.S. Indraprastha University, Sector16C, Dwarka, New Delhi-110078, India
| | - Nimisha Sharma
- University School of Biotechnology, G.G.S. Indraprastha University, Sector16C, Dwarka, New Delhi-110078, India
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17
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Dabas P, Sweta K, Ekka M, Sharma N. Structure function characterization of the ELL Associated Factor (EAF) from Schizosaccharomyces pombe. Gene 2017; 641:117-128. [PMID: 29032152 DOI: 10.1016/j.gene.2017.10.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 10/07/2017] [Accepted: 10/11/2017] [Indexed: 01/03/2023]
Abstract
EAF (ELL Associated Factor) proteins interact with the transcription elongation factor, ELL (Eleven nineteen Lysine rich Leukemia) and enhance its ability to stimulate RNA polymerase II-mediated transcriptional elongation in vitro. Schizosaccharomyces pombe contains a single homolog of EAF (SpEAF), which is not essential for survival of S. pombe in contrast to its essential higher eukaryotic homologs. The physiological role of SpEAF is not well understood. In this study, we show that S. pombe EAF is important in regulating growth of S. pombe cells during normal growth conditions. Moreover, SpEAF is also essential for survival under conditions of DNA damage, while its deletion does not affect growth under environmental stress conditions. Our in vivo structure-function studies further demonstrate that while both the amino and carboxyl terminal domains of SpEAF possess the potential to activate transcription, only the amino terminal domain of SpEAF is involved in interaction with the S. pombe ELL protein. The carboxyl-terminus of SpEAF is required for rescue of the growth defect under normal and DNA damaging conditions that is associated with the absence of SpEAF. Using bioinformatics and circular dichroism spectroscopy, we show that the carboxyl-terminus of SpEAF has a disordered conformation. Furthermore, addition of trifluoroethanol triggered its transition from a disordered to α-helical conformation. Taken together, the results presented here identify novel structural and functional features of SpEAF protein, providing insights into how EAF proteins may enforce transcriptional control of gene expression.
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Affiliation(s)
- Preeti Dabas
- University School of Biotechnology, G.G.S. Indraprastha University, Sector16C, Dwarka, New Delhi 110078, India
| | - Kumari Sweta
- University School of Biotechnology, G.G.S. Indraprastha University, Sector16C, Dwarka, New Delhi 110078, India
| | - Mary Ekka
- CSIR-Institute of Genomics and Integrative Biology, Mathura Road, Opp. Sukhdev Vihar Bus Depot, New Delhi, Delhi 110025, India
| | - Nimisha Sharma
- University School of Biotechnology, G.G.S. Indraprastha University, Sector16C, Dwarka, New Delhi 110078, India.
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18
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Lin S, Luo RT, Ptasinska A, Kerry J, Assi SA, Wunderlich M, Imamura T, Kaberlein JJ, Rayes A, Althoff MJ, Anastasi J, O'Brien MM, Meetei AR, Milne TA, Bonifer C, Mulloy JC, Thirman MJ. Instructive Role of MLL-Fusion Proteins Revealed by a Model of t(4;11) Pro-B Acute Lymphoblastic Leukemia. Cancer Cell 2016; 30:737-749. [PMID: 27846391 DOI: 10.1016/j.ccell.2016.10.008] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 04/21/2016] [Accepted: 10/12/2016] [Indexed: 01/11/2023]
Abstract
The t(4;11)(q21;q23) fuses mixed-lineage leukemia (MLL) to AF4, the most common MLL-fusion partner. Here we show that MLL fused to murine Af4, highly conserved with human AF4, produces high-titer retrovirus permitting efficient transduction of human CD34+ cells, thereby generating a model of t(4;11) pro-B acute lymphoblastic leukemia (ALL) that fully recapitulates the immunophenotypic and molecular aspects of the disease. MLL-Af4 induces a B ALL distinct from MLL-AF9 through differential genomic target binding of the fusion proteins leading to specific gene expression patterns. MLL-Af4 cells can assume a myeloid state under environmental pressure but retain lymphoid-lineage potential. Such incongruity was also observed in t(4;11) patients in whom leukemia evaded CD19-directed therapy by undergoing myeloid-lineage switch. Our model provides a valuable tool to unravel the pathogenesis of MLL-AF4 leukemogenesis.
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Affiliation(s)
- Shan Lin
- Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Roger T Luo
- Department of Medicine, Section of Hematology/Oncology, University of Chicago, Chicago, IL 60637, USA
| | - Anetta Ptasinska
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Jon Kerry
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, NIHR Oxford Biomedical Research Centre Programme, University of Oxford, Oxford OX3 9DS, UK
| | - Salam A Assi
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Mark Wunderlich
- Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Toshihiko Imamura
- Department of Medicine, Section of Hematology/Oncology, University of Chicago, Chicago, IL 60637, USA
| | - Joseph J Kaberlein
- Department of Medicine, Section of Hematology/Oncology, University of Chicago, Chicago, IL 60637, USA
| | - Ahmad Rayes
- Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Mark J Althoff
- Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - John Anastasi
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Maureen M O'Brien
- Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Amom Ruhikanta Meetei
- Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Thomas A Milne
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, NIHR Oxford Biomedical Research Centre Programme, University of Oxford, Oxford OX3 9DS, UK
| | - Constanze Bonifer
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - James C Mulloy
- Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
| | - Michael J Thirman
- Department of Medicine, Section of Hematology/Oncology, University of Chicago, Chicago, IL 60637, USA.
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19
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Sharma N. Regulation of RNA polymerase II-mediated transcriptional elongation: Implications in human disease. IUBMB Life 2016; 68:709-16. [DOI: 10.1002/iub.1538] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 07/14/2016] [Indexed: 01/03/2023]
Affiliation(s)
- Nimisha Sharma
- University School of Biotechnology, G.G.S. Indraprastha University; Dwarka New Delhi 110078 India
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20
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Knutson BA, Smith ML, Walker-Kopp N, Xu X. Super elongation complex contains a TFIIF-related subcomplex. Transcription 2016; 7:133-40. [PMID: 27223670 DOI: 10.1080/21541264.2016.1194027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Super elongation complex (SEC) belongs to a family of RNA polymerase II (Pol II) elongation factors that has similar properties as TFIIF, a general transcription factor that increases the transcription elongation rate by reducing pausing. Although SEC has TFIIF-like functional properties, it apparently lacks sequence and structural homology. Using HHpred, we find that SEC contains an evolutionarily related TFIIF-like subcomplex. We show that the SEC subunit ELL interacts with the Pol II Rbp2 subunit, as expected for a TFIIF-like factor. These findings suggest a new model for how SEC functions as a Pol II elongation factor and how it suppresses Pol II pausing.
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Affiliation(s)
- Bruce A Knutson
- a Department of Biochemistry and Molecular Biology , SUNY Upstate Medical University , Syracuse , NY , USA
| | - Marissa L Smith
- a Department of Biochemistry and Molecular Biology , SUNY Upstate Medical University , Syracuse , NY , USA
| | - Nancy Walker-Kopp
- a Department of Biochemistry and Molecular Biology , SUNY Upstate Medical University , Syracuse , NY , USA
| | - Xia Xu
- a Department of Biochemistry and Molecular Biology , SUNY Upstate Medical University , Syracuse , NY , USA
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21
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Zebrafish eaf1 suppresses foxo3b expression to modulate transcriptional activity of gata1 and spi1 in primitive hematopoiesis. Dev Biol 2014; 388:81-93. [DOI: 10.1016/j.ydbio.2014.01.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/13/2013] [Accepted: 01/11/2014] [Indexed: 12/28/2022]
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22
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Qiao Z, Wang D, Hahn J, Ai J, Wang Z. Pirin down-regulates the EAF2/U19 protein and alleviates its growth inhibition in prostate cancer cells. Prostate 2014; 74:113-20. [PMID: 24272884 PMCID: PMC4827099 DOI: 10.1002/pros.22729] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 08/20/2013] [Indexed: 12/14/2022]
Abstract
BACKGROUND The tumor suppressor ELL associated factor 2 (EAF2/U19) has been reported to induce apoptosis of LNCaP cells and suppress AT6.1 xenograft prostate tumor growth. EAF2/U19 expression level is down-regulated in advanced human prostate cancer. EAF2/U19 is also a putative transcription factor with a transactivation domain and capability of sequence-specific DNA binding. Identification of binding partners and regulators of EAF2/U19 is essential to understand its function in regulating apoptosis/survival of prostate cancer cells. METHODS Through a yeast two-hybrid screening system, we identified Pirin as a binding partner of EAF2. We further determined the interaction between epitope-tagged EAF2/U19 and Pirin by co-immunoprecipitation in mammalian cells. The effect of Pirin on EAF2/U19 inhibition of LNCaP growth was assayed by colony formation. RESULTS Pirin co-immunoprecipitated with EAF2/U19 and the overexpressed Pirin decreased the expression level of EAF2/U19 protein in prostate cancer cell lines LNCaP and PC3. Furthermore, overexpression of EAF2/U19 suppressed LNCaP colony formation, and co-expression of Pirin significantly blocked the growth inhibition induced by EAF2/U19 overexpression. CONCLUSION Pirin is a newly identified binding partner of EAF2/U19 capable of down-regulating EAF2/U19 protein and alleviating its inhibition of prostate cancer cell survival/proliferation. Pirin may play an important role involved in EAF2/U19 function as an androgen-responsive gene and tumor repressor.
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Affiliation(s)
- Zhongjie Qiao
- Department of Urology, The 3rd Affiliated Hospital, Harbin Medical University, Harbin, Heilongjiang, China
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Dan Wang
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Junghyun Hahn
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Junkui Ai
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Zhou Wang
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
- University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
- Correspondence to: Zhou Wang, PhD, Department of Urology, Shadyside Medical Center, Suite G40, 5200 Centre Avenue, Pittsburgh, PA 15232.
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23
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Arumemi F, Bayles I, Paul J, Milcarek C. Shared and discrete interacting partners of ELL1 and ELL2 by yeast two-hybrid assay. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/abb.2013.47101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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24
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Smith ER, Lin C, Garrett AS, Thornton J, Mohaghegh N, Hu D, Jackson J, Saraf A, Swanson SK, Seidel C, Florens L, Washburn MP, Eissenberg JC, Shilatifard A. The little elongation complex regulates small nuclear RNA transcription. Mol Cell 2012; 44:954-65. [PMID: 22195968 DOI: 10.1016/j.molcel.2011.12.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 11/28/2011] [Accepted: 12/06/2011] [Indexed: 01/09/2023]
Abstract
Eleven-nineteen lysine-rich leukemia (ELL) participates in the super elongation complex (SEC) with the RNA polymerase II (Pol II) CTD kinase P-TEFb. SEC is a key regulator in the expression of HOX genes in mixed lineage leukemia (MLL)-based hematological malignancies, in the control of induced gene expression early in development, and in immediate early gene transcription. Here, we identify an SEC-like complex in Drosophila, as well as a distinct ELL-containing complex that lacks P-TEFb and other components of SEC named the "little elongation complex" (LEC). LEC subunits are highly enriched at RNA Pol II-transcribed small nuclear RNA (snRNA) genes, and the loss of LEC results in decreased snRNA expression in both flies and mammals. The specialization of the SEC and LEC complexes for mRNA and snRNA-containing genes, respectively, suggests the presence of specific classes of elongation factors for each class of genes transcribed by RNA polymerase II.
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Affiliation(s)
- Edwin R Smith
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
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25
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ELL facilitates RNA polymerase II pause site entry and release. Nat Commun 2012; 3:633. [PMID: 22252557 PMCID: PMC3272570 DOI: 10.1038/ncomms1652] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 12/16/2011] [Indexed: 01/08/2023] Open
Abstract
Transcription is a multi-stage process that coordinates several steps within the transcription cycle including chromatin reorganization, RNA polymerase II recruitment, initiation, promoter clearance and elongation. Recent advances have identified the super elongation complex, containing the eleven-nineteen lysine-rich leukaemia (ELL) protein, as a key regulator of transcriptional elongation. Here we show that ELL has a diverse and kinetically distinct role before its assembly into the super elongation complex by stabilizing Pol II recruitment/initiation and entry into the pause site. Loss of ELL destabilizes the pre-initiation complexes and results in disruption of early elongation and promoter proximal chromatin structure before recruitment of AFF4 and other super elongation complex components. These changes result in significantly reduced transcriptional activation of rapidly induced genes. Thus, ELL has an early and essential role during rapid high-amplitude gene expression that is required for both Pol II pause site entry and release.
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26
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Zhang Y, Sicot G, Cui X, Vogel M, Wuertzer CA, Lezon-Geyda K, Wheeler J, Harki DA, Muzikar KA, Stolper DA, Dervan PB, Perkins AS. Targeting a DNA binding motif of the EVI1 protein by a pyrrole-imidazole polyamide. Biochemistry 2011; 50:10431-41. [PMID: 22039883 PMCID: PMC3619939 DOI: 10.1021/bi200962u] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The zinc finger protein EVI1 is causally associated with acute myeloid leukemogenesis, and inhibition of its function with a small molecule therapeutic may provide effective therapy for EVI1-expressing leukemias. In this paper we describe the development of a pyrrole-imidazole polyamide to specifically block EVI1 binding to DNA. We first identify essential domains for leukemogenesis through structure-function studies on both EVI1 and the t(3;21)(q26;q22)-derived RUNX1-MDS1-EVI1 (RME) protein, which revealed that DNA binding to the cognate motif GACAAGATA via the first of two zinc finger domains (ZF1, encompassing fingers 1-7) is essential transforming activity. To inhibit DNA binding via ZF1, we synthesized a pyrrole-imidazole polyamide 1, designed to bind to a subsite within the GACAAGATA motif and thereby block EVI1 binding. DNase I footprinting and electromobility shift assays revealed a specific and high affinity interaction between polyamide 1 and the GACAAGATA motif. In an in vivo CAT reporter assay using NIH-3T3-derived cell line with a chromosome-embedded tet-inducible EVI1-VP16 as well as an EVI1-responsive reporter, polyamide 1 completely blocked EVI1-responsive reporter activity. Growth of a leukemic cell line bearing overexpressed EVI1 was also inhibited by treatment with polyamide 1, while a control cell line lacking EVI1 was not. Finally, colony formation by RME was attenuated by polyamide 1 in a serial replating assay. These studies provide evidence that a cell permeable small molecule may effectively block the activity of a leukemogenic transcription factor and provide a valuable tool to dissect critical functions of EVI1 in leukemogenesis.
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Affiliation(s)
- Yi Zhang
- Department of Pathology and Lab Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Géraldine Sicot
- Department of Pathology and Lab Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Xiaohui Cui
- Department of Pathology and Lab Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Marion Vogel
- Department of Pathology and Lab Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Charles A. Wuertzer
- Department of Pathology and Lab Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Kimberly Lezon-Geyda
- Department of Pathology, Yale School of Medicine, New Haven, Connecticut 06510, United States
| | - John Wheeler
- Department of Pathology, Yale School of Medicine, New Haven, Connecticut 06510, United States
| | - Daniel A. Harki
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Katy A. Muzikar
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | | | - Peter B. Dervan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Archibald S. Perkins
- Department of Pathology and Lab Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
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27
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Protein network study of human AF4 reveals its central role in RNA Pol II-mediated transcription and in phosphorylation-dependent regulatory mechanisms. Biochem J 2011; 438:121-31. [PMID: 21574958 PMCID: PMC3174057 DOI: 10.1042/bj20101633] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AF4 belongs to a family of proteins implicated in childhood lymphoblastic leukaemia, FRAXE (Fragile X E site) mental retardation and ataxia. AF4 is a transcriptional activator that is involved in transcriptional elongation. Although AF4 has been implicated in MLL (mixed-lineage leukaemia)-related leukaemogenesis, AF4-dependent physiological mechanisms have not been clearly defined. Proteins that interact with AF4 may also play important roles in mediating oncogenesis, and are potential targets for novel therapies. Using a functional proteomic approach involving tandem MS and bioinformatics, we identified 51 AF4-interacting proteins of various Gene Ontology categories. Approximately 60% participate in transcription regulatory mechanisms, including the Mediator complex in eukaryotic cells. In the present paper we report one of the first extensive proteomic studies aimed at elucidating AF4 protein cross-talk. Moreover, we found that the AF4 residues Thr220 and Ser212 are phosphorylated, which suggests that AF4 function depends on phosphorylation mechanisms. We also mapped the AF4-interaction site with CDK9 (cyclin-dependent kinase 9), which is a direct interactor crucial for the function and regulation of the protein. The findings of the present study significantly expand the number of putative members of the multiprotein complex formed by AF4, which is instrumental in promoting the transcription/elongation of specific genes in human cells.
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Cai L, Phong BL, Fisher AL, Wang Z. Regulation of fertility, survival, and cuticle collagen function by the Caenorhabditis elegans eaf-1 and ell-1 genes. J Biol Chem 2011; 286:35915-35921. [PMID: 21880729 DOI: 10.1074/jbc.m111.270454] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
EAF2, an androgen-regulated protein, interacts with members of the ELL (eleven-nineteen lysine-rich leukemia) transcription factor family and also acts as a tumor suppressor. Although these proteins control transcriptional elongation and perhaps modulate the effects of other transcription factors, the mechanisms of their actions remain largely unknown. To gain new insights into the biology of the EAF2 and ELL family proteins, we used Caenorhabditis elegans as a model to explore the in vivo roles of their worm orthologs. Through the use of transgenic worms, RNAi, and an eaf-1 mutant, we found that both genes are expressed in multiple cell types throughout the worm life cycle and that they play important roles in fertility, survival, and body size regulation. ELL-1 and EAF-1 likely contribute to these activities in part through modulating cuticle synthesis, given that we observed a disrupted cuticle structure in ell-1 RNAi-treated or eaf-1 mutant worms. Consistent with disruption of cuticle structure, loss of either ELL-1 or EAF-1 suppressed the rol phenotype of specific collagen mutants, possibly through the control of dpy-3, dpy-13, and sqt-3 collagen gene expression. Furthermore, we also noted the regulation of collagen expression by ELL overexpression in PC3 human prostate cancer cells. Together, these results reveal important roles for the eaf-1 and ell-1 genes in the regulation of extracellular matrix components.
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Affiliation(s)
- Liquan Cai
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania 15232
| | - Binh L Phong
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania 15232
| | - Alfred L Fisher
- Division of Geriatric Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260.
| | - Zhou Wang
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania 15232.
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MLL fusion proteins preferentially regulate a subset of wild-type MLL target genes in the leukemic genome. Blood 2011; 117:6895-905. [PMID: 21518926 DOI: 10.1182/blood-2010-12-324699] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
MLL encodes a histone methyltransferase that is critical in maintaining gene expression during embryonic development and hematopoiesis. 11q23 translocations result in the formation of chimeric MLL fusion proteins that act as potent drivers of acute leukemia. However, it remains unclear what portion of the leukemic genome is under the direct control of MLL fusions. By comparing patient-derived leukemic cell lines, we find that MLL fusion-bound genes are a small subset of that recognized by wild-type MLL. In an inducible MLL-ENL model, MLL fusion protein binding and changes in H3K79 methylation are limited to a specific portion of the genome, whereas wild-type MLL distributes to a much larger set of gene loci. Surprisingly, among 223 MLL-ENL-bound genes, only 12 demonstrate a significant increase in mRNA expression on induction of the fusion protein. In addition to Hoxa9 and Meis1, this includes Eya1 and Six1, which comprise a heterodimeric transcription factor important in several developmental pathways. We show that Eya1 has the capacity to immortalize hematopoietic progenitor cells in vitro and collaborates with Six1 in hematopoietic transformation assays. Altogether, our data suggest that MLL fusions contribute to the development of acute leukemia through direct activation of a small set of target genes.
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Abstract
MicroRNAs (miRNAs, miRs) are postulated to be important regulators in various cancers, including leukemia. In a large-scale miRNA expression profiling analysis of 435 human miRNAs in 52 acute myeloid leukemia (AML) samples, we found that miR-126 and its minor counterpart in biogenesis, namely, miR-126*, were specifically aberrantly overexpressed in core binding factor (CBF) AMLs including both t(8;21)/AML1-ETO and inv(16)/CBFB-MYH11 samples. Our in vitro gain- and loss-of-function experiments showed that forced expression of miR-126 inhibited apoptosis and increased the viability of AML cells, whereas the opposite effect was observed when endogenous expression of miR-126 was knocked down. In addition, through in vitro colony-forming/replating assays, we demonstrated that forced expression of miR-126 enhanced proliferation and colony-forming/replating capacity of mouse normal bone marrow progenitor cells alone and particularly, in cooperation with AML1-ETO, a fusion gene resulting from t(8;21). Thus, our data shows that miR-126 may play a critical role in the development of CBF leukemias. In the present chapter, the materials and protocols for the study of miR-126 in leukemia are described.
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Affiliation(s)
- Zejuan Li
- Section of Hematology and Oncology, Department of Medicine, The University of Chicago, Chicago, IL, USA
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Self-association mediated by the Ras association 1 domain of AF6 activates the oncogenic potential of MLL-AF6. Blood 2010; 116:63-70. [PMID: 20395419 DOI: 10.1182/blood-2009-09-243386] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MLL is a common target for chromosomal translocations associated with acute leukemia resulting in its fusion with a large variety of nuclear or cytoplasmic proteins that may activate its oncogenic properties by distinct but poorly understood mechanisms. The MLL-AF6 fusion gene represents the most common leukemogenic fusion of mixed lineage leukemia (MLL) to a cytoplasmic partner protein. Here, we identified a highly conserved Ras association (RA1) domain at the amino-terminus of AF6 as the minimal region sufficient for MLL-AF6 mediated myeloid progenitor immortalization in vitro and short latency leukemogenesis in vivo. Moreover, the ability of RA1 to activate MLL oncogenesis is conserved with its Drosophila ortholog, Canoe. Although the AF6 RA1 domain has previously been defined as an interaction surface for guanosine triphosphate-bound Ras, single amino acid substitutions known to abolish the AF6-Ras interaction did not abrogate MLL-AF6-mediated oncogenesis. Furthermore, fusion of MLL to heterologous RA domains of c-Raf1 or RalGDS, or direct fusion of MLL to constitutively active K-RAS, H-RAS, or RAP1 was not sufficient for oncogenic activation of MLL. Rather, the AF6 RA1 domain efficiently mediated self-association, suggesting that constitutive MLL self-association is a more common pathogenic mechanism for MLL oncogenesis than indicated by previous studies of rare MLL fusion partners.
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Wan X, Ji W, Mei X, Zhou J, Liu JX, Fang C, Xiao W. Negative feedback regulation of Wnt4 signaling by EAF1 and EAF2/U19. PLoS One 2010; 5:e9118. [PMID: 20161747 PMCID: PMC2817739 DOI: 10.1371/journal.pone.0009118] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2010] [Accepted: 01/20/2010] [Indexed: 01/02/2023] Open
Abstract
Previous studies indicated that EAF (ELL-associated factor) family members, EAF1 and EAF2/U19, play a role in cancer and embryogenesis. For example, EAF2/U19 may serve as a tumor suppressor in prostate cancer. At the same time, EAF2/U19 is a downstream factor in the non-canonical Wnt 4 signaling pathway required for eye development in Xenopus laevis, and along with EAF1, contributes to convergence and extension movements in zebrafish embryos through Wnt maintenance. Here, we used zebrafish embryos and mammalian cells to show that both EAF1 and EAF2/U19 were up-regulated by Wnt4 (Wnt4a). Furthermore, we found that EAF1 and EAF2/U19 suppressed Wnt4 expression by directly binding to the Wnt4 promoter as seen in chromatin immunoprecipitation assays. These findings indicate that an auto-regulatory negative feedback loop occurs between Wnt4 and the EAF family, which is conserved between zebrafish and mammalian. The rescue experiments in zebrafish embryos showed that early embryonic development required the maintenance of the appropriate levels of Wnt4a through the feedback loop. Others have demonstrated that the tumor suppressors p63, p73 and WT1 positively regulate Wnt4 expression while p21 has the opposite effect, suggesting that maintenance of appropriate Wnt4 expression may also be critical for adult tissue homeostasis and prevention against tumor initiation. Thus, the auto-regulatory negative feedback loop that controls expression of Wnt4 and EAF proteins may play an important role in both embryonic development and tumor suppression. Our findings provide the first convincing line of evidence that EAF and Wnt4 form an auto-regulatory negative feedback loop in vivo.
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Affiliation(s)
- Xiaoyang Wan
- Key Laboratory of Biodiversity and Conservation of Aquatic Organisms, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People's Republic of China.
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Mathews A, Holland L, Yankulov K. The interaction between EAP30 and ELL is modulated by MCM2. FEBS Lett 2009; 583:3431-6. [PMID: 19819239 DOI: 10.1016/j.febslet.2009.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 09/17/2009] [Accepted: 10/02/2009] [Indexed: 10/20/2022]
Abstract
ELL-associated protein 30 (EAP30) was initially characterized as a component of the Holo-ELL complex, which contains the elongation factor ELL. Both ELL and Holo-ELL stimulate RNA pol II elongation in vitro. However, ELL and not Holo-ELL inhibits RNA pol II initiation. It is not clear how these two discrete functions of ELL are regulated. Here we report that mini-chromosome maintenance 2 (MCM2) binds to EAP30 and show that MCM2 competes with ELL for binding to EAP30 thus potentially modulating the stability of Holo-ELL.
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Affiliation(s)
- Amit Mathews
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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Abstract
Mixed lineage leukemia is a very aggressive blood cancer that predominantly occurs in pediatric patients. In contrast to other types of childhood acute leukemias, mixed lineage leukemia presents with a dismal prognosis and despite the availability of advanced treatment methods cure rates have stagnated over the last years. Mixed lineage leukemia is characterized by the presence of MLL fusion proteins that are the result of chromosomal translocations affecting the MLL gene at 11q23. These events juxtapose the amino-terminus of the histone methyltransferase MLL with a variety of different fusion partners that destroy normal histone methyltransferase function of MLL and replace it by heterologous functions contributed by the fusion partner. The resulting chimeras are transcriptional regulators that take control of targets normally controlled by MLL with the clustered HOX homeobox genes as prominent examples. Recent studies suggested that MLL fusion partners activate transcription by two different mechanisms. Some of these proteins are themselves chromatin modifiers that introduce histone acetylation whereas other fusion partners can recruit histone methyltransferases. In particular, histone H3 specific methylation at lysine 79 catalyzed by DOT1L has been recognized as a hallmark of chromatin activated by MLL fusion proteins. Interestingly, several frequent MLL fusion partners seem to coordinate DOT1L activity with a protein complex that stimulates the elongation phase of transcription by phosphorylating the carboxy-terminal repeat domain of RNA polymerase II. The discovery of these novel enzymatic activities that are essentially involved in MLL fusion protein function presents potential new targets for a rational drug development.
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Affiliation(s)
- Robert K Slany
- Department of Genetics, University Erlangen, Erlangen, Germany.
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Zhou J, Feng X, Ban B, Liu J, Wang Z, Xiao W. Elongation factor ELL (Eleven-Nineteen Lysine-rich Leukemia) acts as a transcription factor for direct thrombospondin-1 regulation. J Biol Chem 2009; 284:19142-52. [PMID: 19447890 DOI: 10.1074/jbc.m109.010439] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The eleven-nineteen lysine-rich leukemia (ELL) gene undergoes translocation and fuses in-frame to the multiple lineage leukemia gene in a substantial proportion of patients suffering from acute forms of leukemia. Studies show that ELL indirectly modulates transcription by serving as a regulator for transcriptional elongation as well as for p53, U19/Eaf2, and steroid receptor activities. Our in vitro and in vivo data demonstrate that ELL could also serve as a transcriptional factor to directly induce transcription of the thrombospondin-1 (TSP-1) gene. Experiments using ELL deletion mutants established that full-length ELL is required for the TSP-1 up-regulation and that the transactivation domain likely resides in the carboxyl terminus. Moreover, the DNA binding domain may localize to the first 45 amino acids of ELL. Not surprisingly, multiple lineage leukemia-ELL, which lacks these amino acids, did not induce expression from the TSP-1 promoter. In addition, the ELL core-response element appears to localize in the -1426 to -1418 region of the TSP-1 promoter. Finally, studies using zebrafish confirmed that ELL regulates TSP-1 mRNA expression in vivo, and ELL could inhibit zebrafish vasculogenesis, at least in part, through up-regulating TSP-1. Given the importance of TSP-1 as an anti-angiogenic protein, our findings may have important ramifications for better understanding cancer.
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Affiliation(s)
- Jiangang Zhou
- Key Laboratory of Biodiversity and Conservation of Aquatic Organisms, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
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Liu JX, Hu B, Wang Y, Gui JF, Xiao W. Zebrafish eaf1 and eaf2/u19 mediate effective convergence and extension movements through the maintenance of wnt11 and wnt5 expression. J Biol Chem 2009; 284:16679-16692. [PMID: 19380582 DOI: 10.1074/jbc.m109.009654] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Studies have attributed several functions to the Eaf family, including tumor suppression and eye development. Given the potential association between cancer and development, we set forth to explore Eaf1 and Eaf2/U19 activity in vertebrate embryogenesis, using zebrafish. In situ hybridization revealed similar eaf1 and eaf2/u19 expression patterns. Morpholino-mediated knockdown of either eaf1 or eaf2/u19 expression produced similar morphological changes that could be reversed by ectopic expression of target or reciprocal-target mRNA. However, combination of Eaf1 and Eaf2/U19 (Eafs)-morpholinos increased the severity of defects, suggesting that Eaf1 and Eaf2/U19 only share some functional redundancy. The Eafs knockdown phenotype resembled that of embryos with defects in convergence and extension movements. Indeed, knockdown caused expression pattern changes for convergence and extension movement markers, whereas cell tracing experiments using kaeda mRNA showed a correlation between Eafs knockdown and cell migration defects. Cardiac and pancreatic differentiation markers revealed that Eafs knockdown also disrupted midline convergence of heart and pancreatic organ precursors. Noncanonical Wnt signaling plays a key role in both convergence and extension movements and midline convergence of organ precursors. We found that Eaf1 and Eaf2/U19 maintained expression levels of wnt11 and wnt5. Moreover, wnt11 or wnt5 mRNA partially rescued the convergence and extension movement defects occurring in eafs morphants. Wnt11 and Wnt5 converge on rhoA, so not surprisingly, rhoA mRNA more effectively rescued defects than either wnt11 or wnt5 mRNA alone. However, the ectopic expression of wnt11 and wnt5 did not affect eaf1 and eaf2/u19 expression. These data indicate that eaf1 and eaf2/u19 act upstream of noncanonical Wnt signaling to mediate convergence and extension movements.
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Affiliation(s)
- Jing-Xia Liu
- From the Key Laboratory of Biodiversity and Conservation of Aquatic Organisms, Wuhan 430072, China
| | - Bo Hu
- From the Key Laboratory of Biodiversity and Conservation of Aquatic Organisms, Wuhan 430072, China
| | - Yang Wang
- State Key Laboratory of Fresh Water Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Jian-Fang Gui
- State Key Laboratory of Fresh Water Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Wuhan Xiao
- From the Key Laboratory of Biodiversity and Conservation of Aquatic Organisms, Wuhan 430072, China.
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37
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Abstract
Epigenetics refers to a stable, mitotically perpetuated regulatory mechanism of gene expression without an alteration of the coding sequence. Epigenetic mechanism include DNA methylation and histone tail modifications. Epigenetic regulation is part of physiologic development and becomes abnormal in neoplasia, where silencing of critical genes by DNA methylation or histone deacetylation can contribute to leukemogenesis as an alternative to deletion or loss-of-function mutation. In acute myelogenous leukemia (AML), aberrant DNA methylation can be observed in multiple functionally relevant genes such as p15, p 73, E-cadherin, ID 4, RARbeta2. Abnormal activities of histone tail-modifying enzymes have also been seen in AML, frequently as a direct result of chromosomal translocations. It is now clear that these epigenetic changes play a significant role in development and progression of AML, and thus constitute important targets of therapy. The aim of targeting epigenetic effector protein or "epigenetic therapy" is to reverse epigenetic silencing and reactive various genes to induce a therapeutic effect such as differentiation, growth arrest, or apoptosis. Recent clinical studies have shown the relative safety and efficacy of such epigenetic therapies.
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Affiliation(s)
- Yasuhiro Oki
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA
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38
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Mechanisms of transcriptional regulation by MLL and its disruption in acute leukemia. Int J Hematol 2007; 87:10-8. [DOI: 10.1007/s12185-007-0009-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Accepted: 07/20/2007] [Indexed: 10/22/2022]
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39
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Confirmation of a novel recurrent association: BCR-ABL t(9;22) and t(19;21). ACTA ACUST UNITED AC 2007; 179:127-31. [DOI: 10.1016/j.cancergencyto.2007.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 08/14/2007] [Indexed: 11/23/2022]
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40
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Xiao W, Zhang Q, Habermacher G, Yang X, Zhang AY, Cai X, Hahn J, Liu J, Pins M, Doglio L, Dhir R, Gingrich J, Wang Z. U19/Eaf2 knockout causes lung adenocarcinoma, B-cell lymphoma, hepatocellular carcinoma and prostatic intraepithelial neoplasia. Oncogene 2007; 27:1536-44. [PMID: 17873910 PMCID: PMC2800355 DOI: 10.1038/sj.onc.1210786] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Upregulated gene 19 (U19)/ELL-associated factor 2 (Eaf2) is a potential human tumor suppressor that exhibits frequent allelic loss and downregulation in high-grade prostate cancer. U19/Eaf2, along with its homolog Eaf1, has been reported to regulate transcriptional elongation via interaction with the eleven-nineteen lysine-rich leukemia (ELL) family of proteins. To further explore the tumor-suppressive effects of U19/Eaf2, we constructed and characterized a murine U19/Eaf2-knockout model. Homozygous or heterozygous deletion of U19/Eaf2 resulted in high rates of lung adenocarcinoma, B-cell lymphoma, hepatocellular carcinoma and prostate intraepithelial neoplasia. Within the mouse prostate, U19/Eaf2 deficiency enhanced cell proliferation and increased epithelial cell size. The knockout mice also exhibited cardiac cell hypertrophy. These data indicate a role for U19/Eaf2 in growth suppression and cell size control as well as argue for U19/Eaf2 as a novel tumor suppressor in multiple mouse tissues. The U19/Eaf2 knockout mouse also provides a unique animal model for three important cancers: lung adenocarcinoma, B-cell lymphoma and hepatocellular carcinoma.
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Affiliation(s)
- W Xiao
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, PR China
| | - Q Zhang
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - G Habermacher
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - X Yang
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Robert H Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - A-y Zhang
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Department of Urology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - X Cai
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - J Hahn
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - J Liu
- Department of Urology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - M Pins
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Robert H Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - L Doglio
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - R Dhir
- Department of Pathology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - J Gingrich
- Department of Urology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Z Wang
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Robert H Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Department of Urology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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Abstract
PURPOSE OF REVIEW The Hox family of homeodomain transcription factors plays an important role in regulating definitive hematopoiesis. Recent studies indicate that a common characteristic of poor prognosis acute myeloid leukemia is dysregulated expression of a key group of these Hox proteins. The purpose of this review is to outline recent progress in understanding the role that dysregulation of HOX-gene expression plays in the pathogenesis of myeloid leukemogenesis. RECENT FINDINGS A number of recent studies correlate increased expression of HOXA-genes with poor prognosis cytogenetics in acute myeloid leukemia and mixed lineage leukemia. These studies determine that specific ABD HOXA-genes (HoxA7, 9 and 10) are dysregulated as a group. Many such studies also document co-overexpression of homeodomain proteins of the Meis and Pbx families in poor prognosis leukemia. This is of interest, since Meis and Pbx proteins are common DNA-binding partners for Hox proteins. SUMMARY These findings suggest that a key characteristic of poor prognosis acute myeloid leukemia is increased, differentiation-stage inappropriate expression of the Abd HoxA proteins and their DNA-binding partners. Such results suggest that dysregulation of the 'Hox code' is important in the pathogenesis of myeloid malignancy.
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Affiliation(s)
- Elizabeth A Eklund
- The Feinberg School at Northwestern University and Jesse Brown VHA Medical Center, Chicago, Illinois 60611, USA.
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Hahn J, Xiao W, Jiang F, Simone F, Thirman MJ, Wang Z. Apoptosis induction and growth suppression by U19/Eaf2 is mediated through its ELL-binding domain. Prostate 2007; 67:146-53. [PMID: 17044034 PMCID: PMC2801832 DOI: 10.1002/pros.20481] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND U19/Eaf2 is an androgen-response gene and its downregulation is frequently observed in advanced human prostate cancer. U19/Eaf2 interacts with ELL, a fusion partner of MLL in the (11;19) (q23;p13.1) translocation in acute myeloid leukemia. U19/Eaf2 overexpression induces apoptosis and suppresses xenograft tumor growth. METHODS Transfection and colony formation were used to assay for apoptosis and growth suppression of various U19/Eaf2 mutants. Co-immunoprecipitation was performed to test the interaction between the U19/Eaf2 constructs and ELL. RESULTS The region of U19/Eaf2 essential for apoptosis and growth suppression was mapped to amino acids 68-113. This region was necessary and sufficient for binding ELL. Co-expression of U19/Eaf2 and ELL in 293 cells lead to significant increase in cell death and growth suppression. CONCLUSIONS These observations argue that the interaction with ELL is essential for the induction of apoptosis and growth suppression by U19/Eaf2.
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Affiliation(s)
- Junghyun Hahn
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Wuhan Xiao
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Feng Jiang
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Federico Simone
- Section of Hematology/Oncology, University of Chicago, Chicago, Illinois
| | - Michael J. Thirman
- Section of Hematology/Oncology, University of Chicago, Chicago, Illinois
| | - Zhou Wang
- Department of Molecular Pharmacology and Biological Chemistry, Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Correspondence to: Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232.
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43
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Abstract
PURPOSE OF REVIEW Homeodomain proteins of the Hox family play an important role in regulation of normal hematopoiesis. Substantial evidence also indicates that abnormal Hox protein expression is functionally significant in the pathogenesis of acute myeloid malignancies. The purpose of this review is to outline recent progress in understanding molecular mechanisms involved in Hox regulation of myelopoiesis and myeloid leukemogenesis. RECENT FINDINGS Since Hox proteins function as transcription factors, recent studies have focused on identifying Hox target genes. Various approaches to this problem have been taken, including high throughput screening techniques. In these studies, expression profiles of hematopoietic cells overexpressing various Hox proteins have been analyzed to obtain initial information about potential target genes. Identification of common and unique sets of target genes for various Hox proteins will shed light on function and regulation of the Hox code in developing hematopoietic cells. SUMMARY Recent studies have generated some intriguing information about potential Hox target genes involved in myelopoiesis and leukemogenesis. A number of issues regarding Hox protein function are unresolved, however. These issues include determining whether the effects of various Hox proteins are redundant versus antagonistic, identifying mechanisms which regulate Hox protein function and mechanisms by which Hox proteins modulate target gene transcription in a context-dependent manner.
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Affiliation(s)
- Elizabeth A Eklund
- The Feinberg School of Medicine, Northwestern University and Jesse Brown VHA Medical Center, 710 N. Fairbanks Court, Chicago, IL 60611, USA.
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44
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Ono R, Ihara M, Nakajima H, Ozaki K, Kataoka-Fujiwara Y, Taki T, Nagata KI, Inagaki M, Yoshida N, Kitamura T, Hayashi Y, Kinoshita M, Nosaka T. Disruption of Sept6, a fusion partner gene of MLL, does not affect ontogeny, leukemogenesis induced by MLL-SEPT6, or phenotype induced by the loss of Sept4. Mol Cell Biol 2006; 25:10965-78. [PMID: 16314519 PMCID: PMC1316963 DOI: 10.1128/mcb.25.24.10965-10978.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Septins are evolutionarily conserved GTP-binding proteins that can heteropolymerize into filaments. Recent studies have revealed that septins are involved in not only diverse normal cellular processes but also the pathogenesis of various diseases, including cancer. SEPT6 is ubiquitously expressed in tissues and one of the fusion partner genes of MLL in the 11q23 translocations implicated in acute leukemia. However, the roles of this septin in vivo remain elusive. We have developed Sept6-deficient mice that exhibited neither gross abnormalities, changes in cytokinesis, nor spontaneous malignancy. Sept6 deficiency did not cause any quantitative changes in any of the septins evaluated in this study, nor did it cause any additional changes in the Sept4-deficient mice. Even the depletion of Sept11, a close homolog of Sept6, did not affect the Sept6-null cells in vitro, thus implying a high degree of redundancy in the septin system. Furthermore, a loss of Sept6 did not alter the phenotype of myeloproliferative disease induced by MLL-SEPT6, thus suggesting that Sept6 does not function as a tumor suppressor. To our knowledge, this is the first report demonstrating that a disruption of the translocation partner gene of MLL in 11q23 translocation does not contribute to leukemogenesis by the MLL fusion gene.
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Affiliation(s)
- Ryoichi Ono
- Division of Hematopoietic Factors, The Institute of Medical Science, The University of Tokyo, Minato-ku, Japan
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45
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Abstract
BACKGROUND U19/Eaf2, an androgen-response gene, is downregulated in advanced human prostate cancer specimens and its overexpression can markedly induce apoptosis in prostate cancer cells. Eleven-nineteen Lysine-rich Leukemia (ELL) is an RNA polymerase II transcription elongation factor, initially identified as a fusion partner gene of MLL in the t(11; 19) (q23; p13.1) chromosomal translocation in acute myeloid leukemia. U19/Eaf2 was previously reported as an ELL-associated factor, a potential transcription factor binds to ELL, forming nuclear speckles in vivo. These findings suggest that ELL-U19/Eaf2 interaction is potentially important in prostate cancer progression and/or acute myeloid leukemia. However, the functional significance of U19/Eaf2 interaction with ELL remains unclear. METHODS Using co-transfection, co-immunoprecipitation, protein stability assay and transactivation assay, we characterized the consequence of ELL binding to U19/Eaf2. RESULTS We provide further evidence for U19/Eaf2 as a transcription factor and show that ELL binding is required for nuclear speckle formation of human U19/Eaf2, stabilizes U19/Eaf2 and enhances its transactivation activity. CONCLUSIONS The above observations indicate ELL may be an important factor required for U19/Eaf2 function because U19/Eaf2 nuclear localization and transactivation activity are essential for its function as a transcription factor.
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Affiliation(s)
- Wuhan Xiao
- Department of Urology, Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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46
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Abstract
Advances in molecular genetics have revolutionized our understanding of acute myeloid and lymphoblastic leukemia. Structural and numerical chromosomal aberrations are common, and their detection is vital for leukemia diagnosis, risk stratification, and monitoring of response to therapy. Fusion proteins resulting from chromosomal translocations are necessary but not sufficient for leukemogenesis, and there is intense research activity to elucidate the cooperating molecular abnormalities that may be suitable targets for novel therapeutic approaches. Candidate gene approaches have identified mutations in kinases and transcription factors in a proportion of patients, but more comprehensive genomic approaches are required. Gene expression profiling accurately classifies known subtypes of acute leukemia and has highlighted potentially leukemogenic abnormalities in gene expression. Newer techniques, such as single-nucleotide polymorphism arrays to analyze changes in gene copy number and zygosity, cancer genome sequencing, and RNA interference, are promising tools to identify mutations, although at present, data from these approaches are limited. This review provides an overview of these techniques in clinical practice and as research tools to develop new therapeutic approaches in pediatric leukemia.
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Affiliation(s)
- Charles G Mullighan
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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Li Y, Fanning AS, Anderson JM, Lavie A. Structure of the conserved cytoplasmic C-terminal domain of occludin: identification of the ZO-1 binding surface. J Mol Biol 2005; 352:151-64. [PMID: 16081103 DOI: 10.1016/j.jmb.2005.07.017] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 07/05/2005] [Accepted: 07/07/2005] [Indexed: 11/26/2022]
Abstract
Occludin is a transmembrane protein localized at tight junctions whose functions are complex yet poorly understood. Current evidence supports a role for occludin in both the formation of the paracellular barrier and in cell signaling. While the N-terminal extracellular domains of occludin mediate homotypic adhesion, the distal C-terminal cytoplasmic domain of occludin controls protein targeting and endocytosis. The C terminus can also bind to the scaffolding proteins ZO-1, ZO-2, ZO-3, cingulin, the membrane trafficking protein VAP33, and the cytoskeletal protein F-actin, suggesting an important role for this domain. This domain is highly homologous to an important functional domain in the C terminus of the ELL family of RNA polymerase II transcription factors. To explore the function of occludin, we determined the high-resolution crystal structure of its C-terminal distal cytoplasmic domain. The structure comprises three helices that form two separate anti-parallel coiled-coils and a loop that packs tightly against one of the coiled-coils. Using in vitro binding studies and site-directed mutagenesis, we have identified a large positively charged surface that contains the binding site for ZO-1, and this surface is required for proper localization of occludin to cell-cell junctions. On the basis of sequence conservation, we predict that occludin domains from different species and the C-terminal domain of the ELL transcription factors share a very similar structure. Our results provide a model to further test the function of occludin and its binding to other proteins.
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Affiliation(s)
- Yuanhe Li
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
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48
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Gerber MA, Shilatifard A, Eissenberg JC. Mutational analysis of an RNA polymerase II elongation factor in Drosophila melanogaster. Mol Cell Biol 2005; 25:7803-11. [PMID: 16107725 PMCID: PMC1190276 DOI: 10.1128/mcb.25.17.7803-7811.2005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ELL family of proteins function in vitro as elongation factors for RNA polymerase II. Deletion studies have defined domains in mammalian ELL required for transcription elongation activity and RNA polymerase binding in vitro, for transformation of cultured cells when overexpressed, and for leukemogenesis and cell proliferation as part of a leukemic fusion protein. The goal of this study was to identify domains required for chromosome targeting and viability in the unique Drosophila ELL (dELL) protein. Here, we show that an N-terminal domain of dELL is necessary and sufficient for targeting to transcriptionally active puff sites in chromatin, supporting a role for this domain in recruiting dELL to elongating RNA polymerase II. We demonstrate that a central domain of dELL is required for rapid mobilization of ELL during the heat shock response, suggesting a regulatory function for this domain. Unexpectedly, transgenic dELL in which the N-terminal chromosome binding domain is deleted can complement the recessive lethality of mutations in ELL, suggesting that Drosophila ELL has an essential activity in development distinct from its role as an RNA polymerase II elongation factor.
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Affiliation(s)
- Mark A Gerber
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, MO 63104, USA
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49
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Taki T, Akiyama M, Saito S, Ono R, Taniwaki M, Kato Y, Yuza Y, Eto Y, Hayashi Y. The MYO1F, unconventional myosin type 1F, gene is fused to MLL in infant acute monocytic leukemia with a complex translocation involving chromosomes 7, 11, 19 and 22. Oncogene 2005; 24:5191-7. [PMID: 15897884 DOI: 10.1038/sj.onc.1208711] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We analysed a complex translocation involving chromosomes 7, 11, 19 and 22 in infant acute monocytic leukemia, and identified that the MLL gene on 11q23 was fused to the unconventional myosin type 1F, MYO1F, gene on 19p13.2-13.3. MYO1F consists of at least 28 exons and was predicted to encode a 1098-amino-acid with an N-terminal head domain containing both ATP-binding and actin-binding sequences, a neck domain with a single IQ motif, and a tail with TH1, TH2 and SH3 domains. Northern blot analysis of RNAs prepared from multiple tissues showed that the expression of approximately 4-kb transcripts appeared constant in most tissues examined. However, MYO1F was expressed in only three of 22 leukemic cell lines. The MLL-MYO1F fusion protein contains almost the entire MYO1F, however, C-terminal MYO1F has neither the transactivation domain nor the dimerization domain found in various MLL fusion partners. Further analysis of this novel type of MLL fusion protein would provide new insights into leukemogenesis. MYO1F is the fourth partner gene of MLL on 19p13. At the cytogenetic level, it may be difficult to distinguish MLL-ENL, MLL-ELL, MLL-EEN and MLL-MYO1F fusions created by t(11;19)(q23;p13), and it is likely that cases of t(11;19) lacking a known fusion gene may result in this gene fusion.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Cell Line, Tumor
- Chromosomes, Human, Pair 11
- Chromosomes, Human, Pair 19
- Chromosomes, Human, Pair 22
- Chromosomes, Human, Pair 7
- DNA-Binding Proteins/genetics
- Female
- Gene Rearrangement
- Histone-Lysine N-Methyltransferase
- Humans
- Infant
- Leukemia, Monocytic, Acute/genetics
- Molecular Sequence Data
- Myeloid-Lymphoid Leukemia Protein
- Myosin Type I/genetics
- Proto-Oncogenes/genetics
- Transcription Factors/genetics
- Translocation, Genetic
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Affiliation(s)
- Tomohiko Taki
- Department of Molecular Laboratory Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, 465 Kajii-cho Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan
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50
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Kong SE, Banks CAS, Shilatifard A, Conaway JW, Conaway RC. ELL-associated factors 1 and 2 are positive regulators of RNA polymerase II elongation factor ELL. Proc Natl Acad Sci U S A 2005; 102:10094-8. [PMID: 16006523 PMCID: PMC1177379 DOI: 10.1073/pnas.0503017102] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In human cells, the ELL family of transcription factors includes at least three members, which are all capable of stimulating the overall rate of elongation by RNA polymerase II by suppressing transient pausing by the enzyme at many sites along DNA. In this report, we identify the ELL-associated factors (EAF)1 and EAF2 as strong positive regulators of ELL elongation activity. Our findings provide insights into the structure and function of ELL family transcription factors, and they bring to light direct roles for the EAF proteins in regulation of RNA polymerase II transcription.
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Affiliation(s)
- Stephanie E Kong
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
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