1
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Malik S, Roeder RG. Regulation of the RNA polymerase II pre-initiation complex by its associated coactivators. Nat Rev Genet 2023; 24:767-782. [PMID: 37532915 PMCID: PMC11088444 DOI: 10.1038/s41576-023-00630-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2023] [Indexed: 08/04/2023]
Abstract
The RNA polymerase II (Pol II) pre-initiation complex (PIC) is a critical node in eukaryotic transcription regulation, and its formation is the major rate-limiting step in transcriptional activation. Diverse cellular signals borne by transcriptional activators converge on this large, multiprotein assembly and are transduced via intermediary factors termed coactivators. Cryogenic electron microscopy, multi-omics and single-molecule approaches have recently offered unprecedented insights into both the structure and cellular functions of the PIC and two key PIC-associated coactivators, Mediator and TFIID. Here, we review advances in our understanding of how Mediator and TFIID interact with activators and affect PIC formation and function. We also discuss how their functions are influenced by their chromatin environment and selected cofactors. We consider how, through its multifarious interactions and functionalities, a Mediator-containing and TFIID-containing PIC can yield an integrated signal processing system with the flexibility to determine the unique temporal and spatial expression pattern of a given gene.
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Affiliation(s)
- Sohail Malik
- Laboratory of Biochemistry & Molecular Biology, The Rockefeller University, New York, NY, USA.
| | - Robert G Roeder
- Laboratory of Biochemistry & Molecular Biology, The Rockefeller University, New York, NY, USA
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2
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Structure and function of Pygo in organ development dependent and independent Wnt signalling. Biochem Soc Trans 2020; 48:1781-1794. [PMID: 32677664 DOI: 10.1042/bst20200393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/22/2020] [Accepted: 06/24/2020] [Indexed: 11/17/2022]
Abstract
Pygo is a nuclear protein containing two conserved domains, NHD and PHD, which play important roles in embryonic development and carcinogenesis. Pygo was first identified as a core component of the Wnt/β-catenin signalling pathway. However, it has also been reported that the function of Pygo is not always Wnt/β-catenin signalling dependent. In this review, we summarise the functions of both domains of Pygo and show that their functions are synergetic. The PHD domain mainly combines with transcription co-factors, including histone 3 and Bcl9/9l. The NHD domain mainly recruits histone methyltransferase/acetyltransferase (HMT/HAT) to modify lysine 4 of the histone 3 tail (H3K4) and interacts with Chip/LIM-domain DNA-binding proteins (ChiLS) to form enhanceosomes to regulate transcriptional activity. Furthermore, we summarised chromatin modification differences of Pygo in Drosophila (dPygo) and vertebrates, and found that Pygo displayes a chromatin silencing function in Drosophila, while in vertebates, Pygo has a chromatin-activating function due to the two substitution of two amino acid residues. Next, we confirmed the relationship between Pygo and Bcl9/9l and found that Pygo-Bcl/9l are specifically partnered both in the nucleus and in the cytoplasm. Finally, we discuss whether transcriptional activity of Pygo is Wnt/β-catenin dependent during embryonic development. Available information indications that the transcriptional activity of Pygo in embryonic development is either Wnt/β-catenin dependent or independent in both tissue-specific and cell-specific-modes.
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3
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Xie YY, Mo CL, Cai YH, Wang WJ, Hong XX, Zhang KK, Liu QF, Liu YJ, Hong JJ, He T, Zheng ZZ, Mo W, Li BA. Pygo2 Regulates Adiposity and Glucose Homeostasis via β-Catenin-Axin2-GSK3β Signaling Pathway. Diabetes 2018; 67:2569-2584. [PMID: 30279163 DOI: 10.2337/db18-0311] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/13/2018] [Indexed: 11/13/2022]
Abstract
Wnt/β-catenin signaling plays a key role in regulating adipogenesis through indirectly inhibiting the expression of C/EBPα and peroxisome proliferator-activated receptor γ (PPARγ); however, the detailed molecular mechanism remains poorly understood. Moreover, the factor(s) that determines the Wnt/β-catenin output level during adipogenesis is also not completely defined. In this study, we showed that Pygo2 exhibited a declined expression pattern during adipocyte differentiation, resulting in an attenuated Wnt/β-catenin output level. The mechanism study indicated that Pygo2 inhibition led to the downregulation of Axin2, a constitutive Wnt target, in the cytoplasm. Consequently, Axin2-bound GSK3β was released and translocated into the nucleus to phosphorylate C/EBPβ and Snail, resulting in an increase in the DNA binding activity of C/EBPβ and decreased protein stability of Snail, which subsequently activated the expression of C/EBPα and PPARγ. Consistent with this, embryonic fibroblasts from Pygo2-/- mice exhibited spontaneous adipocyte differentiation, and adipocyte precursor-specific Pygo2-deficient mice exhibited increased adiposity with decreased energy expenditure. We further showed impaired glucose tolerance and decreased systemic insulin sensitivity in Pygo2-deficient mice. Our study revealed an association between Pygo2 function and obesity or diabetes.
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Affiliation(s)
- Yuan-Yuan Xie
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Chun-Li Mo
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Yi-Huang Cai
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Wen-Jie Wang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Xin-Xin Hong
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Kun-Kun Zhang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Qing-Feng Liu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Yun-Jia Liu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Jing-Jing Hong
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Ting He
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Zhong-Zheng Zheng
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Wei Mo
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Bo-An Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
- Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
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4
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Zhong L, Mu H, Wen B, Zhang W, Wei Q, Gao G, Han J, Cao S. Long non-coding RNAs involved in the regulatory network during porcine pre-implantation embryonic development and iPSC induction. Sci Rep 2018; 8:6649. [PMID: 29703926 PMCID: PMC5923264 DOI: 10.1038/s41598-018-24863-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 04/05/2018] [Indexed: 12/16/2022] Open
Abstract
Long non-coding RNAs (lncRNA) play a key role in the orchestration of transcriptional regulation during development and many other cellular processes. The importance of the regulatory co-expression network was highlighted in the identification of the mechanism of these processes in humans and mice. However, elucidation of the properties of porcine lncRNAs involved in the regulatory network during pre-implantation embryonic development and fibroblast reprogramming to induced pluripotent stem cell (iPSC) has been limited to date. Using a weighted gene co-expression network analysis, we constructed the regulatory network and determined that the novel lncRNAs were functionally involved in key events of embryonic development during the pre-implantation period; moreover, reprogramming could be delineated by a small number of potentially functional modules of co-expressed genes. These findings indicate that lncRNAs may be involved in the transcriptional regulation of zygotic genome activation, first lineage segregation and somatic reprogramming to pluripotency. Furthermore, we performed a conservation and synteny analysis with the significant lncRNAs involved in these vital events and validated the results via experimental assays. In summary, the current findings provide a valuable resource to dissect the protein coding gene and lncRNA regulatory networks that underlie the progressive development of embryos and somatic reprogramming.
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Affiliation(s)
- Liang Zhong
- The Animal Science and Technology College, Beijing University of Agriculture, Beijing, China.,State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Haiyuan Mu
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Bingqiang Wen
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Wei Zhang
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Qingqing Wei
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Ge Gao
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Center for Bioinformatics, Peking University, Beijing, China
| | - Jianyong Han
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China.
| | - Suying Cao
- The Animal Science and Technology College, Beijing University of Agriculture, Beijing, China. .,Beijing Key Laboratory of Traditional Chinese Veterinary Medicine, Beijing University of Agriculture, Beijing, China.
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5
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Pygo2 activates MDR1 expression and mediates chemoresistance in breast cancer via the Wnt/β-catenin pathway. Oncogene 2016; 35:4787-97. [PMID: 26876203 DOI: 10.1038/onc.2016.10] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 12/24/2015] [Accepted: 12/27/2015] [Indexed: 12/19/2022]
Abstract
The Wnt/β-catenin pathway has important roles in chemoresistance and multidrug resistance 1 (MDR1) expression in some cancers, but its involvement in breast cancer and the underlying molecular mechanism are undefined. In this study, we demonstrated that the Wnt/β-catenin pathway is activated in chemoresistant breast cancer cells. Using a Wnt pathway-specific PCR array screening assay, we detected that Pygo2, a newly identified Wnt/β-catenin pathway component, was the most upregulated gene in the resistant cells. Additional experiments indicated that Pygo2 activated MDR1 expression in the resistant cells via the Wnt/β-catenin pathway. Moreover, the inhibition of Pygo2 expression restored the chemotherapeutic drug sensitivity of the resistant cells and reduced the breast cancer stem cell population in these cells in response to chemotherapy. Importantly, these activities induced by Pygo2 were mediated by MDR1. We also determined the effect of Pygo2 on the sensitivity of breast tumors resistant to doxorubicin in a mouse model. Finally, RNA samples from 64 paired patient tumors (before and after chemotherapy) highly and significantly overexpressed Pygo2 and/or MDR1 after treatment, thus underlining a pivotal role for the Pygo2-mediated Wnt/β-catenin pathway in the clinical chemoresistance of breast cancer. Our data represent the first implication of the Wnt/β-catenin pathway in breast cancer chemoresistance and identify potential new targets to treat the recurrence of breast cancer.
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6
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Fiedler M, Graeb M, Mieszczanek J, Rutherford TJ, Johnson CM, Bienz M. An ancient Pygo-dependent Wnt enhanceosome integrated by Chip/LDB-SSDP. eLife 2015; 4:e09073. [PMID: 26312500 PMCID: PMC4571689 DOI: 10.7554/elife.09073] [Citation(s) in RCA: 39] [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: 05/29/2015] [Accepted: 08/26/2015] [Indexed: 12/15/2022] Open
Abstract
TCF/LEF factors are ancient context-dependent enhancer-binding proteins that are activated by β-catenin following Wnt signaling. They control embryonic development and adult stem cell compartments, and their dysregulation often causes cancer. β-catenin-dependent transcription relies on the NPF motif of Pygo proteins. Here, we use a proteomics approach to discover the Chip/LDB-SSDP (ChiLS) complex as the ligand specifically binding to NPF. ChiLS also recognizes NPF motifs in other nuclear factors including Runt/RUNX2 and Drosophila ARID1, and binds to Groucho/TLE. Studies of Wnt-responsive dTCF enhancers in the Drosophila embryonic midgut indicate how these factors interact to form the Wnt enhanceosome, primed for Wnt responses by Pygo. Together with previous evidence, our study indicates that ChiLS confers context-dependence on TCF/LEF by integrating multiple inputs from lineage and signal-responsive factors, including enhanceosome switch-off by Notch. Its pivotal function in embryos and stem cells explain why its integrity is crucial in the avoidance of cancer.
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Affiliation(s)
- Marc Fiedler
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Michael Graeb
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Juliusz Mieszczanek
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Trevor J Rutherford
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Christopher M Johnson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Mariann Bienz
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
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7
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Miller MS, Rialdi A, Ho JSY, Tilove M, Martinez-Gil L, Moshkina NP, Peralta Z, Noel J, Melegari C, Maestre AM, Mitsopoulos P, Madrenas J, Heinz S, Benner C, Young JAT, Feagins AR, Basler CF, Fernandez-Sesma A, Becherel OJ, Lavin MF, van Bakel H, Marazzi I. Senataxin suppresses the antiviral transcriptional response and controls viral biogenesis. Nat Immunol 2015; 16:485-94. [PMID: 25822250 PMCID: PMC4406851 DOI: 10.1038/ni.3132] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 02/27/2015] [Indexed: 12/14/2022]
Abstract
The human helicase senataxin (SETX) has been linked to the neurodegenerative diseases amyotrophic lateral sclerosis (ALS4) and ataxia with oculomotor apraxia (AOA2). Here we identified a role for SETX in controlling the antiviral response. Cells that had undergone depletion of SETX and SETX-deficient cells derived from patients with AOA2 had higher expression of antiviral mediators in response to infection than did wild-type cells. Mechanistically, we propose a model whereby SETX attenuates the activity of RNA polymerase II (RNAPII) at genes stimulated after a virus is sensed and thus controls the magnitude of the host response to pathogens and the biogenesis of various RNA viruses (e.g., influenza A virus and West Nile virus). Our data indicate a potentially causal link among inborn errors in SETX, susceptibility to infection and the development of neurologic disorders.
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Affiliation(s)
- Matthew S Miller
- 1] Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA. [2] Department of Biochemistry and Biomedical Sciences, Institute for Infectious Diseases Research, McMaster Immunology Research Centre, McMaster University, Hamilton, Canada
| | - Alexander Rialdi
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Jessica Sook Yuin Ho
- Laboratory of Methyltransferases in Development and Disease, Institute of Molecular and Cell Biology, Singapore
| | - Micah Tilove
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Luis Martinez-Gil
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Natasha P Moshkina
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Zuleyma Peralta
- Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Justine Noel
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Camilla Melegari
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Ana M Maestre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Panagiotis Mitsopoulos
- Microbiome and Disease Tolerance Centre, Department of Microbiology and Immunology, McGill University, Montreal, Canada
| | - Joaquín Madrenas
- Microbiome and Disease Tolerance Centre, Department of Microbiology and Immunology, McGill University, Montreal, Canada
| | - Sven Heinz
- The Salk Institute for Biological Studies, La Jolla, California, USA
| | - Chris Benner
- The Salk Institute for Biological Studies, La Jolla, California, USA
| | | | - Alicia R Feagins
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Christopher F Basler
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Ana Fernandez-Sesma
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Olivier J Becherel
- The University of Queensland, UQ Centre for Clinical Research, Herston, Australia
| | - Martin F Lavin
- The University of Queensland, UQ Centre for Clinical Research, Herston, Australia
| | - Harm van Bakel
- 1] Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York, USA. [2] Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Ivan Marazzi
- 1] Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA. [2] Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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8
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Diversity in TAF proteomics: consequences for cellular differentiation and migration. Int J Mol Sci 2014; 15:16680-97. [PMID: 25244017 PMCID: PMC4200853 DOI: 10.3390/ijms150916680] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/25/2014] [Accepted: 08/27/2014] [Indexed: 12/31/2022] Open
Abstract
Development is a highly controlled process of cell proliferation and differentiation driven by mechanisms of dynamic gene regulation. Specific DNA binding factors for establishing cell- and tissue-specific transcriptional programs have been characterised in different cell and animal models. However, much less is known about the role of “core transcription machinery” during cell differentiation, given that general transcription factors and their spatiotemporally patterned activity govern different aspects of cell function. In this review, we focus on the role of TATA-box associated factor 4 (TAF4) and its functional isoforms generated by alternative splicing in controlling lineage-specific differentiation of normal mesenchymal stem cells and cancer stem cells. In the light of our recent findings, induction, control and maintenance of cell differentiation status implies diversification of the transcription initiation apparatus orchestrated by alternative splicing.
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9
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Xie G, Yu Z, Jia D, Jiao R, Deng WM. E(y)1/TAF9 mediates the transcriptional output of Notch signaling in Drosophila. J Cell Sci 2014; 127:3830-9. [PMID: 25015288 DOI: 10.1242/jcs.154583] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Transcriptional activation of Notch signaling targets requires the formation of a ternary complex that involves the intracellular domain of the Notch receptor (NICD), DNA-binding protein Suppressor of Hairless [Su(H), RPBJ in mammals] and coactivator Mastermind (Mam). Here, we report that E(y)1/TAF9, a component of the transcription factor TFIID complex, interacts specifically with the NICD-Su(H)-Mam complex to facilitate the transcriptional output of Notch signaling. We identified E(y)1/TAF9 in a large-scale in vivo RNA interference (RNAi) screen for genes that are involved in a Notch-dependent mitotic-to-endocycle transition in Drosophila follicle cells. Knockdown of e(y)1/TAF9 displayed Notch-mutant-like phenotypes and defects in target gene and activity reporter expression in both the follicle cells and wing imaginal discs. Epistatic analyses in these two tissues indicated that E(y)1/TAF9 functions downstream of Notch cleavage. Biochemical studies in S2 cells demonstrated that E(y)1/TAF9 physically interacts with the transcriptional effectors of Notch signaling Su(H) and NICD. Taken together, our data suggest that the association of the NICD-Su(H)-Mastermind complex with E(y)1/TAF9 in response to Notch activation recruits the transcription initiation complex to induce Notch target genes, coupling Notch signaling with the transcription machinery.
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Affiliation(s)
- Gengqiang Xie
- Department of Biological Science, Florida State University, Tallahassee, FL 32304-4295, USA
| | - Zhongsheng Yu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Datun Road 15, Beijing 100101, China
| | - Dongyu Jia
- Department of Biological Science, Florida State University, Tallahassee, FL 32304-4295, USA
| | - Renjie Jiao
- Department of Biological Science, Florida State University, Tallahassee, FL 32304-4295, USA
| | - Wu-Min Deng
- Department of Biological Science, Florida State University, Tallahassee, FL 32304-4295, USA
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10
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Abstract
Reactive Oxygen Species (ROS) are ubiquitous metabolites in all aerobic organisms. Traditionally ROS have been considered as harmful, accidental byproducts of cellular functions involving electron transport chains or electron transfer. However, it is now recognized that controlled production of ROS has significant signaling functions, for example, in pathogen defense, in the regulation of stomatal closure, or in cell-to-cell signaling. ROS formation in subcellular compartments is critical to act as “alarm” signal in the response to stress, and the concept of ROS as primarily signaling substances has emerged. The involvement of ROS in several developmental and inducible processes implies that there must be coordinated function of signaling network(s) that govern ROS responses and subsequent processes. The air pollutant ozone can be used as a useful tool to elucidate the function of apoplastic ROS: O3 degrades in cell wall into various ROS which are interpreted as ROS with signaling function inducing downstream responses. We have used ozone as a tool in mutant screens and transcript profiling-reverse genetics to identify genes involved in processes related to the signaling function of ROS. We review here our recent findings in the elucidation of apoplastic ROS sensing, signaling, and interaction with various symplastic components.
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11
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Kazantseva J, Kivil A, Tints K, Kazantseva A, Neuman T, Palm K. Alternative splicing targeting the hTAF4-TAFH domain of TAF4 represses proliferation and accelerates chondrogenic differentiation of human mesenchymal stem cells. PLoS One 2013; 8:e74799. [PMID: 24098348 PMCID: PMC3788782 DOI: 10.1371/journal.pone.0074799] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 08/06/2013] [Indexed: 01/07/2023] Open
Abstract
Transcription factor IID (TFIID) activity can be regulated by cellular signals to specifically alter transcription of particular subsets of genes. Alternative splicing of TFIID subunits is often the result of external stimulation of upstream signaling pathways. We studied tissue distribution and cellular expression of different splice variants of TFIID subunit TAF4 mRNA and biochemical properties of its isoforms in human mesenchymal stem cells (hMSCs) to reveal the role of different isoforms of TAF4 in the regulation of proliferation and differentiation. Expression of TAF4 transcripts with exons VI or VII deleted, which results in a structurally modified hTAF4-TAFH domain, increases during early differentiation of hMSCs into osteoblasts, adipocytes and chondrocytes. Functional analysis data reveals that TAF4 isoforms with the deleted hTAF4-TAFH domain repress proliferation of hMSCs and preferentially promote chondrogenic differentiation at the expense of other developmental pathways. This study also provides initial data showing possible cross-talks between TAF4 and TP53 activity and switching between canonical and non-canonical WNT signaling in the processes of proliferation and differentiation of hMSCs. We propose that TAF4 isoforms generated by the alternative splicing participate in the conversion of the cellular transcriptional programs from the maintenance of stem cell state to differentiation, particularly differentiation along the chondrogenic pathway.
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Affiliation(s)
| | - Anri Kivil
- Protobios LLC, Tallinn, Estonia
- The Department of Gene Technology, Tallinn University of Technology, Tallinn, Estonia
| | | | - Anna Kazantseva
- Protobios LLC, Tallinn, Estonia
- The Department of Gene Technology, Tallinn University of Technology, Tallinn, Estonia
| | | | - Kaia Palm
- Protobios LLC, Tallinn, Estonia
- The Department of Gene Technology, Tallinn University of Technology, Tallinn, Estonia
- * E-mail:
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12
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Chen WY, Zhang J, Geng H, Du Z, Nakadai T, Roeder RG. A TAF4 coactivator function for E proteins that involves enhanced TFIID binding. Genes Dev 2013; 27:1596-609. [PMID: 23873942 DOI: 10.1101/gad.216192.113] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The multisubunit TFIID plays a direct role in transcription initiation by binding to core promoter elements and directing preinitiation complex assembly. Although TFIID may also function as a coactivator through direct interactions with promoter-bound activators, mechanistic aspects of this poorly defined function remain unclear. Here, biochemical studies show a direct TFIID-E-protein interaction that (1) is mediated through interaction of a novel E-protein activation domain (activation domain 3 [AD3]) with the TAF homology (TAFH) domain of TAF4, (2) is critical for activation of a natural target gene by an E protein, and (3) mechanistically acts by enhancing TFIID binding to the core promoter. Complementary assays establish a gene-specific role for the TAFH domain in TFIID recruitment and activation of a large subset of genes in vivo. These results firmly establish TAF4 as a bona fide E-protein coactivator as well as a mechanism involving facilitated TFIID binding through direct interaction with an E-protein activation domain.
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Affiliation(s)
- Wei-Yi Chen
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York 10065, USA
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Rider MA, Zou J, Vanlandingham D, Nuckols JT, Higgs S, Zhang Q, Lacey M, Kim J, Wang G, Hong YS. Quantitative proteomic analysis of the Anopheles gambiae (Diptera: Culicidae) midgut infected with o'nyong-nyong virus. JOURNAL OF MEDICAL ENTOMOLOGY 2013; 50:1077-1088. [PMID: 24180113 DOI: 10.1603/me12155] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Alphaviruses are arthropod-borne pathogens that infect a range of hosts. In humans and other mammals, alphavirus infection can cause severe disease. In mosquito hosts, however, there are generally few symptoms. Little is known about the cellular responses of mosquitoes that allow them to cope with infection. In this investigation, a six-plex tandem mass tagging proteomic approach was used to study protein accumulation changes in the midgut of Anopheles gambiae (Giles) (Diptera: Culicidae) mosquitoes infected with o'nyong-nyong virus (Togaviridae, Alphavirus). Five hundred thirty-six nonredundant proteins were identified. Twenty-two were found in significantly different quantities in infected midguts compared with controls. Of interest, analysis revealed molecular pathways possibly targeted by virus proteins, such as those involving TAF4 and DNA polymerase phi proteins. Also identified was an FK506-binding protein. FK506-binding protein orthologs have been described as conserved host resistance factors, which suppress dengue and West Nile virus infection in human HeLa cells. This investigation constitutes the first study of the midgut-specific proteome of An. gambiae in relation to alphavirus infection. Our findings offer insight into mosquito immunity, including factors that possibly contribute to the different pathological outcomes observed in vertebrate and insect hosts.
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Affiliation(s)
- Mark A Rider
- Department of Tropical Medicine, Tulane University, 1430 Tulane Ave, SL-17, New Orleans, LA 70112, USA
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14
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Singh K, Dilworth FJ. Differential modulation of cell cycle progression distinguishes members of the myogenic regulatory factor family of transcription factors. FEBS J 2013; 280:3991-4003. [DOI: 10.1111/febs.12188] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 02/01/2013] [Accepted: 02/05/2013] [Indexed: 12/29/2022]
Affiliation(s)
- Kulwant Singh
- Sprott Center for Stem Cell Research; Ottawa Hospital Research Institute; ON; Canada
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15
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Cadigan KM, Waterman ML. TCF/LEFs and Wnt signaling in the nucleus. Cold Spring Harb Perspect Biol 2012; 4:cshperspect.a007906. [PMID: 23024173 DOI: 10.1101/cshperspect.a007906] [Citation(s) in RCA: 516] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
T-cell factor/lymphoid enhancer factor (TCF/LEF) transcription factors are the major end point mediators of Wnt/Wingless signaling throughout metazoans. TCF/LEFs are multifunctional proteins that use their sequence-specific DNA-binding and context-dependent interactions to specify which genes will be regulated by Wnts. Much of the work to define their actions has focused on their ability to repress target gene expression when Wnt signals are absent and to recruit β-catenin to target genes for activation when Wnts are present. Recent advances have highlighted how these on/off actions are regulated by Wnt signals and stabilized β-catenin. In contrast to invertebrates, which typically contain one TCF/LEF protein that can both activate and repress Wnt targets, gene duplication and isoform complexity of the family in vertebrates have led to specialization, in which individual TCF/LEF isoforms have distinct activities.
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Affiliation(s)
- Ken M Cadigan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 48109-1048, USA
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16
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Scheer E, Delbac F, Tora L, Moras D, Romier C. TFIID TAF6-TAF9 complex formation involves the HEAT repeat-containing C-terminal domain of TAF6 and is modulated by TAF5 protein. J Biol Chem 2012; 287:27580-92. [PMID: 22696218 DOI: 10.1074/jbc.m112.379206] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The general transcription factor TFIID recognizes specifically the core promoter of genes transcribed by eukaryotic RNA polymerase II, nucleating the assembly of the preinitiation complex at the transcription start site. However, the understanding in molecular terms of TFIID assembly and function remains poorly understood. Histone fold motifs have been shown to be extremely important for the heterodimerization of many TFIID subunits. However, these subunits display several evolutionary conserved noncanonical features when compared with histones, including additional regions whose role is unknown. Here we show that the conserved additional C-terminal region of TFIID subunit TAF6 can be divided into two domains: a small middle domain (TAF6M) and a large C-terminal domain (TAF6C). Our crystal structure of the TAF6C domain from Antonospora locustae at 1.9 Å resolution reveals the presence of five conserved HEAT repeats. Based on these data, we designed several mutants that were introduced into full-length human TAF6. Surprisingly, the mutants affect the interaction between TAF6 and TAF9, suggesting that the formation of the complex between these two TFIID subunits do not only depend on their histone fold motifs. In addition, the same mutants affect even more strongly the interaction between TAF6 and TAF9 in the context of a TAF5-TAF6-TAF9 complex. Expression of these mutants in HeLa cells reveals that most of them are unstable, suggesting their poor incorporation within endogenous TFIID. Taken together, our results suggest that the conserved additional domains in histone fold-containing subunits of TFIID and of co-activator SAGA are important for the assembly of these complexes.
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Affiliation(s)
- Elisabeth Scheer
- Département de Biologie Intégrative, Institut de Génétique et Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg (UDS), CNRS, INSERM, 1 rue Laurent Fries, B.P. 10142, 67404 Illkirch Cedex, France
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17
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Abstract
Wnts are conserved, secreted signaling proteins that can influence cell behavior by stabilizing β-catenin. Accumulated β-catenin enters the nucleus, where it physically associates with T-cell factor (TCF) family members to regulate target gene expression in many developmental and adult tissues. Recruitment of β-catenin to Wnt response element (WRE) chromatin converts TCFs from transcriptional repressors to activators. This review will outline the complex interplay between factors contributing to TCF repression and coactivators working with β-catenin to regulate Wnt targets. In addition, three variations of the standard transcriptional switch model will be discussed. One is the Wnt/β-catenin symmetry pathway in Caenorhabditis elegans, where Wnt-mediated nuclear efflux of TCF is crucial for activation of targets. Another occurs in vertebrates, where distinct TCF family members are associated with repression and activation, and recent evidence suggests that Wnt signaling facilitates a "TCF exchange" on WRE chromatin. Finally, a "reverse switch" mechanism for target genes that are directly repressed by Wnt/β-catenin signaling occurs in Drosophila cells. The diversity of TCF regulatory mechanisms may help to explain how a small group of transcription factors can function in so many different contexts to regulate target gene expression.
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Affiliation(s)
- Ken M Cadigan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
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18
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Core promoter recognition complex changes accompany liver development. Proc Natl Acad Sci U S A 2011; 108:3906-11. [PMID: 21368148 DOI: 10.1073/pnas.1100640108] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Recent studies of several key developmental transitions have brought into question the long held view of the basal transcriptional apparatus as ubiquitous and invariant. In an effort to better understand the role of core promoter recognition and coactivator complex switching in cellular differentiation, we have examined changes in transcription factor IID (TFIID) and cofactor required for Sp1 activation/Mediator during mouse liver development. Here we show that the differentiation of fetal liver progenitors to adult hepatocytes involves a wholesale depletion of canonical cofactor required for Sp1 activation/Mediator and TFIID complexes at both the RNA and protein level, and that this alteration likely involves silencing of transcription factor promoters as well as protein degradation. It will be intriguing for future studies to determine if a novel and as yet unknown core promoter recognition complex takes the place of TFIID in adult hepatocytes and to uncover the mechanisms that down-regulate TFIID during this critical developmental transition.
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Pygo2 associates with MLL2 histone methyltransferase and GCN5 histone acetyltransferase complexes to augment Wnt target gene expression and breast cancer stem-like cell expansion. Mol Cell Biol 2010; 30:5621-35. [PMID: 20937768 DOI: 10.1128/mcb.00465-10] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Resent studies have identified Pygopus as a core component of the β-catenin/T-cell factor (TCF)/lymphoid-enhancing factor 1 (LEF) transcriptional activation complex required for the expression of canonical Wg/Wnt target genes in Drosophila. However, the biochemical involvement of mammalian Pygopus proteins in β-catenin/TCF/LEF gene activation remains controversial. In this study, we perform a series of molecular/biochemical experiments to demonstrate that Pygo2 associates with histone-modifying enzymatic complexes, specifically the MLL2 histone methyltransferase (HMT) and STAGA histone acetyltransferase (HAT) complexes, to facilitate their interaction with β-catenin and to augment Wnt1-induced, TCF/LEF-dependent transcriptional activation in breast cancer cells. We identify a critical domain in Pygo2 encompassing the first 47 amino acids that mediates its HMT/HAT interaction. We further demonstrate the importance of this domain in Pygo2's ability to transcriptionally activate both artificial and endogenous Wnt target genes and to expand breast cancer stem-like cells in culture. This work now links mechanistically Pygo2's role in histone modification to its enhancement of the Wnt-dependent transcriptional program and cancer stem-like cell expansion.
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Cadigan KM, Peifer M. Wnt signaling from development to disease: insights from model systems. Cold Spring Harb Perspect Biol 2010; 1:a002881. [PMID: 20066091 DOI: 10.1101/cshperspect.a002881] [Citation(s) in RCA: 240] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
One of the early surprises in the study of cell adhesion was the discovery that beta-catenin plays dual roles, serving as an essential component of cadherin-based cell-cell adherens junctions and also serving as the key regulated effector of the Wnt signaling pathway. Here, we review our current model of Wnt signaling and discuss how recent work using model organisms has advanced our understanding of the roles Wnt signaling plays in both normal development and in disease. These data help flesh out the mechanisms of signaling from the membrane to the nucleus, revealing new protein players and providing novel information about known components of the pathway.
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Affiliation(s)
- Ken M Cadigan
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1048, USA
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Müller F, Zaucker A, Tora L. Developmental regulation of transcription initiation: more than just changing the actors. Curr Opin Genet Dev 2010; 20:533-40. [PMID: 20598874 DOI: 10.1016/j.gde.2010.06.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 05/26/2010] [Accepted: 06/02/2010] [Indexed: 11/29/2022]
Abstract
The traditional model of transcription initiation nucleated by the TFIID complex has suffered significant erosion in the last decade. The discovery of cell-specific paralogs of TFIID subunits and a variety of complexes that replace TFIID in transcription initiation of protein coding genes have been paralleled by the description of diverse core promoter sequences. These observations suggest an additional level of regulation of developmental and tissue-specific gene expression at the core promoter level. Recent work suggests that this regulation may function through specific roles of distinct TBP-type factors and TBP-associated factors (TAFs), however the picture emerging is still far from complete. Here we summarize the proposed models of transcription initiation by alternative initiation complexes in distinct stages of developmental specialization during vertebrate ontogeny.
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Affiliation(s)
- Ferenc Müller
- Department of Medical and Molecular Genetics, Division of Reproductive and Child Health, Institute of Biomedical Research, University of Birmingham, B15 2TT Edgbaston, Birmingham, UK
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Song H, Goetze S, Bischof J, Spichiger-Haeusermann C, Kuster M, Brunner E, Basler K. Coop functions as a corepressor of Pangolin and antagonizes Wingless signaling. Genes Dev 2010; 24:881-6. [PMID: 20439429 DOI: 10.1101/gad.561310] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Wingless (Wg) signaling regulates expression of its target genes via Pangolin and Armadillo, and their interacting cofactors. In the absence of Wg, Pangolin mediates transcriptional repression. In the presence of Wg, Pangolin, Armadillo, and a cohort of coactivators mediate transcriptional activation. Here we uncover Coop (corepressor of Pan) as a Pangolin-interacting protein. Coop and Pangolin form a complex on DNA containing a Pangolin/TCF-binding motif. Overexpression of Coop specifically represses Wg target genes, while loss of Coop function causes derepression. Finally, we show that Coop antagonizes the binding of Armadillo to Pangolin, providing a mechanism for Coop-mediated repression of Wg target gene transcription.
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Affiliation(s)
- Haiyun Song
- Institute of Molecular Life Sciences, University of Zurich, CH-8057 Zurich, Switzerland
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23
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The transcriptional activity of Pygopus is enhanced by its interaction with cAMP-response-element-binding protein (CREB)-binding protein. Biochem J 2009; 422:493-501. [PMID: 19555349 DOI: 10.1042/bj20090134] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Pygopus is a core component of the beta-catenin/TCF (T-cell factor) transcriptional activation complex required for the expression of canonical Wnt target genes. Recent evidence suggests that Pygopus could interpret histone methylation associated with target genes and it was shown to be required for histone acetylation. The involvement of a specific acetyltransferase, however, was not determined. In this report, we demonstrate that Pygopus can interact with the HAT (histone acetyltransferase) CBP [CREB (cAMP-responsive-element-binding protein)-binding protein]. The interaction is via the NHD (N-terminal homology domain) of Pygopus, which binds to two regions in the vicinity of the HAT domain of CBP. Transfected and endogenous hPygo2 (human Pygopus2) and CBP proteins co-immunoprecipitate in HEK-293 (human embryonic kidney 293) cells and both proteins co-localize in SW480 colorectal cancer cells. The interaction with CBP also enhances both DNA-tethered and TCF/LEF1 (lymphoid enhancing factor 1)-dependent transcriptional activity of Pygopus. Furthermore, immunoprecipitated Pygopus protein complexes displayed CBP-dependent histone acetyltransferase activity. Our data support a model in which the NHD region of Pygopus is required to augment TCF/beta-catenin-mediated transcriptional activation by a mechanism that includes both transcriptional activation and histone acetylation resulting from the recruitment of the CBP histone acetyltransferase.
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24
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Kessler R, Hausmann G, Basler K. The PHD domain is required to link Drosophila Pygopus to Legless/beta-catenin and not to histone H3. Mech Dev 2009; 126:752-9. [PMID: 19493659 DOI: 10.1016/j.mod.2009.04.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 04/08/2009] [Accepted: 04/10/2009] [Indexed: 10/20/2022]
Abstract
In Drosophila Pygopus (Pygo) and Legless (Lgs)/BCL9 are integral components of the nuclear Wnt/Wg signaling machine. Despite intense research, ideas that account for their mode of action remain speculative. One proposition, based on a recently discovered function of PHD fingers, is that Pygo, through its PHD, may decipher the histone code. We found that human, but not Drosophila, Pygo robustly interacts with a histone-H3 peptide methylated at lysine-4. The different binding behavior is due to a single amino acid change that appears unique to Drosophilidae Pygo proteins. Rescue experiments with predicted histone binding mutants showed that in Drosophila the ability to bind histones is not essential. Further experiments with Pygo-Lgs fusions instead demonstrated that the crucial role of the PHD is to provide an interaction motif to bind Lgs. Our results reveal an interesting evolutionary dichotomy in Pygo structure-function, as well as evidence underpinning the chain of adaptors model.
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Affiliation(s)
- Roman Kessler
- Institut für Molekularbiologie, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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25
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Distinct modes of gene regulation by a cell-specific transcriptional activator. Proc Natl Acad Sci U S A 2009; 106:4213-8. [PMID: 19251649 DOI: 10.1073/pnas.0808347106] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The architectural layout of a eukaryotic RNA polymerase II core promoter plays a role in general transcriptional activation. However, its role in tissue-specific expression is not known. For example, differing modes of its recognition by general transcription machinery can provide an additional layer of control within which a single tissue-restricted transcription factor may operate. Erythroid Kruppel-like factor (EKLF) is a hematopoietic-specific transcription factor that is critical for the activation of subset of erythroid genes. We find that EKLF interacts with TATA binding protein-associated factor 9 (TAF9), which leads to important consequences for expression of adult beta-globin. First, TAF9 functionally supports EKLF activity by enhancing its ability to activate the beta-globin gene. Second, TAF9 interacts with a conserved beta-globin downstream promoter element, and ablation of this interaction by beta-thalassemia-causing mutations decreases its promoter activity and disables superactivation. Third, depletion of EKLF prevents recruitment of TAF9 to the beta-globin promoter, whereas depletion of TAF9 drastically impairs beta-promoter activity. However, a TAF9-independent mode of EKLF transcriptional activation is exhibited by the alpha-hemoglobin-stabilizing protein (AHSP) gene, which does not contain a discernable downstream promoter element. In this case, TAF9 does not enhance EKLF activity and depletion of TAF9 has no effect on AHSP promoter activation. These studies demonstrate that EKLF directs different modes of tissue-specific transcriptional activation depending on the architecture of its target core promoter.
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