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Ezawa M, Kouno F, Kubo H, Sakuma T, Yamamoto T, Kinoshita T. Pou5f3.3 is involved in establishment and maintenance of hematopoietic cells during Xenopus development. Tissue Cell 2021; 72:101531. [PMID: 33798831 DOI: 10.1016/j.tice.2021.101531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/05/2021] [Accepted: 03/15/2021] [Indexed: 11/30/2022]
Abstract
Three POU family class V gene homologues are expressed in the development of Xenopus. In contrast to the expression of Pou5f3.1 and Pou5f3.2 in organogenesis, Pou5f3.3 is expressed during oogenesis in ovary. We investigated the expression and function of Pou5f3.3 in organogenesis of Xenopus laevis. RT-PCR and immunohistochemical analysis indicated that Pou5f3.3 was expressed in a small number of adult liver cells and blood cells. Immunocytochemical investigation proved that Bmi1, a marker for hematopoietic progenitor cells, was co-expressed in Pou5f3.3-expressing small spherical cells in the peripheral blood. In anemic induction by intraperitoneal injection of phenyl hydrazine, the number of Pou5f3.3-expressing cells significantly increased within 3 days after phenyl hydrazine injection. In CRISPR/Cas mutagenesis of Pou5f3.3, Bmi1-positive hematopoietic progenitor cell count decreased in the hematopoietic dorsal-lateral plate (DLP) region, resulting in a considerable reduction in peripheral blood cells. CRISPR/Cas-induced hematopoietic deficiency was completely rescued by Pou5f3.3 supplementation, but not by Pou5f3.1 or Pou5f3.2. Transplantation experiments using the H2B-GFP transgenic line demonstrated that DLP-derived Pou5f3.3-positive and Bmi1-positive cells were translocated into the liver and bone through the bloodstream. These results suggest that Pou5f3.3 plays an essential role in the establishment and maintenance of hematopoietic progenitor cells during Xenopus development.
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Affiliation(s)
- Minami Ezawa
- Department of Life Science, Faculty of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
| | - Fumika Kouno
- Department of Life Science, Faculty of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
| | - Hideo Kubo
- Department of Membrane Biochemistry, Tokyo Metropolitan Institute of Medical Science, Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
| | - Tetsushi Sakuma
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Tsutomu Kinoshita
- Department of Life Science, Faculty of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan.
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2
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Inomata C, Yuikawa T, Nakayama-Sadakiyo Y, Kobayashi K, Ikeda M, Chiba M, Konishi C, Ishioka A, Tsuda S, Yamasu K. Involvement of an Oct4-related PouV gene, pou5f3/pou2, in neurogenesis in the early neural plate of zebrafish embryos. Dev Biol 2020; 457:30-42. [DOI: 10.1016/j.ydbio.2019.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 01/03/2023]
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3
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Schmidhauser M, Renz PF, Tsikrika P, Freimann R, Wutz A, Wrana JL, Beyer TA. Gaining Insights into the Function of Post-Translational Protein Modification Using Genome Engineering and Molecular Cell Biology. J Mol Biol 2019; 431:3920-3932. [PMID: 31306665 DOI: 10.1016/j.jmb.2019.07.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/03/2019] [Accepted: 07/05/2019] [Indexed: 11/18/2022]
Abstract
Modifications by kinases are a fast and reversible mechanism to diversify the function of the targeted proteins. The OCT4 transcription factor is essential for preimplantation development and pluripotency of embryonic stem cells (ESC), and its activity is tightly regulated by post-transcriptional modifications. Several phosphorylation sites have been identified by systemic approaches and their functions proposed. Here, we combined molecular and cellular biology with CRISPR/Cas9-mediated genome engineering to pinpoint the function of serine 12 of OCT4 in ESCs. Using chemical inhibitors and an antibody specific to OCT4 phosphorylated on S12, we identified cyclin-dependent kinase (CDK) 7 as upstream kinase. Surprisingly, generation of isogenic mESCs that endogenously ablate S12 revealed no effects on pluripotency and self-renewal, potentially due to compensation by other phosphorylation events. Our approach reveals that modification of distinct amino acids by precise genome engineering can help to clarify the functions of post-translational modifications on proteins encoded by essential gene in an endogenous context.
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Affiliation(s)
| | - Peter F Renz
- Institute for Molecular Health Sciences, ETH Zurich, Switzerland; Life Science Zurich Graduate School, Molecular Life Science program, University of Zürich, Switzerland
| | - Panagiota Tsikrika
- Institute for Molecular Health Sciences, ETH Zurich, Switzerland; Life Science Zurich Graduate School, Molecular Life Science program, University of Zürich, Switzerland
| | - Remo Freimann
- Institute for Molecular Health Sciences, ETH Zurich, Switzerland
| | - Anton Wutz
- Institute for Molecular Health Sciences, ETH Zurich, Switzerland
| | - Jeffrey L Wrana
- Lunenfeld-Tanenbaum Research Institute, Toronto, Ontario, Canada
| | - Tobias A Beyer
- Institute for Molecular Health Sciences, ETH Zurich, Switzerland.
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4
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Nakanoh S, Agata K. Evolutionary view of pluripotency seen from early development of non-mammalian amniotes. Dev Biol 2019; 452:95-103. [PMID: 31029690 DOI: 10.1016/j.ydbio.2019.04.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/22/2019] [Accepted: 04/24/2019] [Indexed: 11/24/2022]
Abstract
Early embryonic cells are capable of acquiring numerous developmental fates until they become irreversibly committed to specific lineages depending on intrinsic determinants and/or regional interactions. From fertilization to gastrulation, such pluripotent cells first increase in number and then turn to undergoing differentiation. Mechanisms regulating pluripotency in each species attract great interest in developmental biology. Also, outlining the evolutionary background of pluripotency can enhance our understanding of mammalian pluripotency and provide a broader view of early development of vertebrates. Here, we introduce integrative models of pluripotent states in amniotes (mammals, birds and reptiles) to offer a comprehensive overview of widely accepted knowledge about mammalian pluripotency and our recent findings in non-mammalian amniotes, such as chicken and gecko. In particular, we describe 1) the IL6/Stat3 signaling pathway as a positive regulator of naive pluripotency, 2) Fgf/Erk signaling as a process that prepares cells for differentiation, 3) the role of the interactions between these two signaling pathways during the transition from pluripotency to differentiation, and 4) functional diversification of two transcription factors, Class V POUs and Nanog. In the last section, we also briefly discuss possible relationships of unique cell cycle properties of early embryonic cells with signaling pathways and developmental potentials in the pluripotent cell states.
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Affiliation(s)
- Shota Nakanoh
- Division of Embryology, National Institute for Basic Biology, Okazaki 444-8787, Japan; Wellcome-MRC Cambridge Stem Cell Institute, Anne McLaren Laboratory, University of Cambridge, Cambridge CB2 0SZ, UK; Department of Surgery, University of Cambridge, Cambridge CB2 0QQ, UK.
| | - Kiyokazu Agata
- Graduate Course in Life Science, Gakushuin University, Toyoshima-ku, Tokyo 171-8588, Japan.
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5
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Kobayashi K, Khan A, Ikeda M, Nakamoto A, Maekawa M, Yamasu K. In vitro analysis of the transcriptional regulatory mechanism of zebrafish pou5f3. Exp Cell Res 2018; 364:28-41. [PMID: 29366809 DOI: 10.1016/j.yexcr.2018.01.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 12/11/2017] [Accepted: 01/17/2018] [Indexed: 12/18/2022]
Abstract
Zebrafish pou5f3 (previously named pou2), a close homologue of mouse Oct4, encodes a PouV-family transcription factor. pou5f3 has been implicated in diverse aspects of developmental regulation during embryogenesis. In the present study, we addressed the molecular function of Pou5f3 as a transcriptional regulator and the mechanism by which pou5f3 expression is transcriptionally regulated. We examined the influence of effector genes on the expression of the luciferase gene under the control of the upstream 2.1-kb regulatory DNA of pou5f3 (Luc-2.2) in HEK293T and P19 cells. We first confirmed that Pou5f3 functions as a transcriptional activator both in cultured cells and embryos, which confirmed autoregulation of pou5f3 in embryos. It was further shown that Luc-2.2 was activated synergistically by pou5f3 and sox3, which is similar to the co-operative activity of Oct4 and Sox2 in mice, although synergy between pou5f3 and sox2 was less obvious in this zebrafish system. The effects of pou5f3 deletion constructs on the regulation of Luc-2.2 expression revealed different roles for the three subregions of the N-terminal region in Pou5f3 in terms of its regulatory functions and co-operativity with Sox3. Electrophoretic mobility shift assays confirmed that Pou5f3 and Sox3 proteins specifically bind to adjacent sites in the 2.1-kb DNA and that there is an interaction between the two proteins. The synergy with sox3 was unique to pou5f3-the other POU factor genes examined did not show such synergy in Luc-2.2 regulation. Finally, functional interaction was observed between pou5f3 and sox3 in embryos in terms of the regulation of dorsoventral patterning and convergent extension movement. These findings together demonstrate co-operative functions of pou5f3 and sox3, which are frequently coexpressed in early embryos, in the regulation of early development.
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Affiliation(s)
- Kana Kobayashi
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Alam Khan
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Masaaki Ikeda
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Andrew Nakamoto
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Masato Maekawa
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Kyo Yamasu
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan; Saitama University Brain Science Institute, Saitama University, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
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Intrachromosomal looping is required for activation of endogenous pluripotency genes during reprogramming. Cell Stem Cell 2013; 13:30-5. [PMID: 23747202 DOI: 10.1016/j.stem.2013.05.012] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 04/19/2013] [Accepted: 05/17/2013] [Indexed: 11/30/2022]
Abstract
Generation of induced pluripotent stem cells (iPSCs) by defined factors is an extremely inefficient process, because there is a strong epigenetic block preventing cells from achieving pluripotency. Here we report that virally expressed factors bound to the promoters of their target genes to the same extent in both iPSCs and unreprogrammed cells (URCs). However, expression of endogenous pluripotentcy genes was observed only in iPSCs. Comparison of local chromatin structure of the OCT4 locus revealed that there was a cohesin-complex-mediated intrachromosomal loop that juxtaposes a downstream enhancer to the gene's promoter, enabling activation of endogenous stemness genes. None of these long-range interactions were observed in URCs. Knockdown of the cohesin-complex gene SMC1 by RNAi abolished the intrachromosomal interaction and affected pluripotency. These findings highlight the importance of the SMC1-orchestrated intrachromosomal loop as a critical epigenetic barrier to the induction of pluripotency.
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Solubility partner IF2 Domain I enables high yield synthesis of transducible transcription factors in Escherichia coli. Protein Expr Purif 2011; 80:145-51. [PMID: 21757009 DOI: 10.1016/j.pep.2011.06.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2011] [Revised: 06/24/2011] [Accepted: 06/26/2011] [Indexed: 12/21/2022]
Abstract
Since the discovery that somatic cells could be reprogrammed back to a pluripotent state through the viral expression of a certain set of transcription factors, there has been great interest in reprogramming using a safer and more clinically relevant protein-based approach. However, the search for an efficient reprogramming approach utilizing the transcription factors in protein form requires a significant amount of protein material. Milligram quantities of transcription factors are challenging to obtain due to low yields and poor solubility. In this work, we describe enhanced production of the pluripotency transcription factors Oct4, Sox2, Klf4, Nanog, and Lin28 after fusing them to a solubility partner, IF2 Domain I (IF2D1). We expressed and purified milligram quantities of the fusion proteins. Though the transcription factor passenger proteins became insoluble after removal of the IF2D1, the un-cleaved Oct4, Sox2, Klf4, and Nanog fusion proteins exhibited specific binding to their consensus DNA sequences. However, when we administered the un-cleaved IF2D1-Oct4-R9 and IF2D1-Sox2-R9 to fibroblasts and measured their ability to influence transcriptional activity, we found that they were not fully bioactive; IF2D1-Oct4-R9 and IF2D1-Sox2-R9 influenced only a subset of their downstream gene targets. Thus, while the IF2D1 solubility partner enabled soluble production of the fusion protein at high levels, it did not yield fully bioactive transcription factors.
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Cao Y, Oswald F, Wacker SA, Bundschu K, Knöchel W. Reversal of Xenopus Oct25 function by disruption of the POU domain structure. J Biol Chem 2010; 285:8408-21. [PMID: 20064932 DOI: 10.1074/jbc.m109.064386] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Xenopus Oct25 is a POU family subclass V (POU-V) transcription factor with a distinct domain structure. To investigate the contribution of different domains to the function of Oct25, we have performed gain of function analyses. Deletions of the N- or C-terminal regions and of the Hox domain (except its nuclear localization signal) result in mutants being indistinguishable from the wild type protein in the suppression of genes promoting germ layer formation. Deletion of the complete POU domain generates a mutant that has no effect on embryogenesis. However, disruption of the alpha-helical structures in the POU domain, even by a single amino acid mutation, causes reversal of protein function. Overexpression of such mutants leads to dorsalization of embryos and formation of secondary axial structures. The underlying mechanism is an enhanced transcription of genes coding for antagonists of the ligands for ventralizing bone morphogenetic protein and Wnt pathways. Corresponding deletion mutants of Xenopus Oct60, Oct91, or mouse Oct4 also exhibit such a dominant-negative effect. Therefore, our results reveal that the integrity of the POU domain is crucial for the function of POU-V transcription factors in the regulation of genes that promote germ layer formation.
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Affiliation(s)
- Ying Cao
- Institute of Biochemistry, University of Ulm, D-89081 Ulm, Germany
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9
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Lim HY, Do HJ, Lee WY, Kim DK, Seo HG, Chung HJ, Park JK, Chang WK, Kim JH, Kim JH. Implication of human OCT4 transactivation domains for self-regulatory transcription. Biochem Biophys Res Commun 2009; 385:148-53. [PMID: 19445899 DOI: 10.1016/j.bbrc.2009.05.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Accepted: 05/08/2009] [Indexed: 01/27/2023]
Abstract
OCT4 plays a crucial role in pluripotency and self-renewal of embryonic stem cells. OCT4 is also expressed in testicular germ cell tumors (GCTs), suggesting the important function of OCT4 as an oncogenic factor in GCTs. To understand the molecular mechanism of human OCT4 (hOCT4) in tumorigenesis as well as stemness, we identified hOCT4 transactivation domains in human embryonic carcinoma cells. Context analyses of heterologous GAL4 and natural hOCT4 revealed that each N-terminal domain or C-terminal domain independently stimulated transcriptional activity, and that both domains are required for synergistic transactivation by deletion mapping analysis. Dose-dependent overexpression of exogenous hOCT4 significantly decreased the transcriptional activity of the hOCT4 promoter. This inhibition was reversed by the removal of one or both domains. These results suggest that the inhibitory effect of hOCT4 is mediated by transactivation domains, and that the self-regulation of hOCT4 may be mediated via a negative feedback loop in pluripotent cells.
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Affiliation(s)
- Hye-Young Lim
- Department of Biomedical Science, CHA Stem Cell Institute, College of Life Science, CHA University, Pochon-si, Gyeonggi-do, South Korea
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10
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Smith AEF, Ford KG. Use of altered-specificity binding Oct-4 suggests an absence of pluripotent cell-specific cofactor usage. Nucleic Acids Res 2005; 33:6011-23. [PMID: 16243786 PMCID: PMC1266064 DOI: 10.1093/nar/gki907] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Oct-4 is a POU domain transcription factor that is critical for maintaining pluripotency and for stem cell renewal. Previous studies suggest that transcription regulation by Oct-4 at particular enhancers requires the input of a postulated E1A-like cofactor that is specific to pluripotent cells. However, such studies have been limited to the use of enhancer elements that bind other POU-protein family members in addition to Oct-4, thus preventing a ‘clean’ assessment of any Oct-4:cofactor relationships. Other attempts to study Oct-4 functionality in a more ‘stand-alone’ situation target Oct-4 transactivation domains to DNA using heterologous binding domains, a methodology which is known to generate artificial data. To circumvent these issues, an altered-specificity binding Oct-4 (Oct-4RR) and accompanying binding site, which binds Oct-4RR only, were generated. This strategy has previously been shown to maintain Oct-1:cofactor interactions that are highly binding-site and protein/binding conformation specific. This system therefore allows a stand-alone study of Oct-4 function in pluripotent versus differentiated cells, without interference from endogenous POU factors and with minimal deviation from bound wild-type protein characteristics. Subsequently, it was demonstrated that Oct-4RR and the highly transactive regions of its N-terminus determined here, and its C-terminus, have the same transactivation profile in pluripotent and differentiated cells, thus providing strong evidence against the existence of such a pluripotent cell-specific Oct-4 cofactor.
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Affiliation(s)
- Alexander E F Smith
- King's College London, Department of Haematological and Molecular Medicine, King's College School of Medicine, The Rayne Institute, 123 Coldharbour Lane, London SE5 9NU, UK.
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Niwa H, Masui S, Chambers I, Smith AG, Miyazaki JI. Phenotypic complementation establishes requirements for specific POU domain and generic transactivation function of Oct-3/4 in embryonic stem cells. Mol Cell Biol 2002; 22:1526-36. [PMID: 11839818 PMCID: PMC134688 DOI: 10.1128/mcb.22.5.1526-1536.2002] [Citation(s) in RCA: 235] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcription factors of the POU family govern cell fate through combinatorial interactions with coactivators and corepressors. The POU factor Oct-3/4 can define differentiation, dedifferentation, or self-renewal of pluripotent embryonic stem (ES) cells in a sensitive, dose-dependent manner (H. Niwa, J.-I. Miyazali, and A. G. Smith, Nat. Genet. 24:372-376, 2000). Here we have developed a complementation assay based on the ability of Oct-3/4 transgenes to rescue self-renewal in conditionally null ES cells and used this to define which domains of Oct-3/4 are required to sustain the undifferentiated stem cell phenotype. Surprisingly, we found that molecules lacking either the N-terminal or C-terminal transactivation domain, though not both, can effectively replace full-length Oct-3/4. Furthermore, a fusion of the heterologous transactivation domain of Oct-2 to the Oct-3/4 POU domain can also sustain self-renewal. Thus, the unique function of Oct-3/4 in ES cell propagation resides in combination of the specific POU domain with a generic proline-rich transactivation domain. Interestingly, however, Oct-3/4 target gene expression elicited by the N- and C-terminal transactivation domains is not identical, indicating that at least one class of genes activated by Oct-3/4 is not required for ES cell propagation.
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Affiliation(s)
- Hitoshi Niwa
- Stem Cell Regulation Research, Area of Molecular Therapeutics, Course of Advanced Medicine, Osaka University Graduate School of Medicine, Suita C, Osaka 565-0871, Japan.
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12
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Abstract
Embryonic stem (ES) cells are pluripotent cells directly derived from early stage embryos that retain the ability to differentiate into all cell types. This unique feature is the basis of various applications of ES cell technology such as in vitro models of mammalian development, germline transgenesis to make knockout mice, and a generic source for cell therapy in regenerative medicine. To achieve success in these applications, the pluripotency of ES cells has to be kept stable during long-term culture in vitro, leading to the necessity of determining the molecular basis for maintaining ES self-renewal. This paper summarizes the recent progress in this area, focusing mainly on the LIF signaling pathway and the transcription factor Oct-3/4. Although it is still unclear how these components works together, a model is presented here that provides a plan to solve this problem.
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Affiliation(s)
- H Niwa
- Stem Cell Regulation Research, Area of Molecular Therapeutics, Course of Advanced Medicine, Osaka University Graduate School of Medicine, Suita, Japan.
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Abstract
The development of efficient methods for establishing germline competent chicken embryonic stem (ES) cell lines has proved elusive. In the mouse embryo, expression of oct 3/4 is limited to pluripotent cells and primordial germ cells; regulatory sequences of this gene have been used to derive germline competent mouse ES cell lines by the continuous ablation of differentiated cells in culture using drug selection. To apply this technique to chickens several strategies were employed to analyze the chicken genome for oct 3/4, a member of the highly conserved POU gene family. PCR and Southern hybridization experiments with primers and probes based on mouse oct 3/4 sequences indicated that oct 3/4-like sequences are not present in the chicken genome. Also, analysis of mRNA from Stage 14 and 20 (H&H) chick embryos by reverse transcription PCR and the screening of a Stage 20 (H&H) chick embryo cDNA library with mouse oct 3/4-based primers and probes indicated that oct 3/4-like sequences are not expressed in the early chick embryo. The apparent absence of oct 3/4 in chickens, despite the conservation of the gene in mammals and urodeles, is discussed in terms of possible implications for the mode of chicken PGC formation in relation to that in other vertebrates.
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Affiliation(s)
- S Soodeen-Karamath
- Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada
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14
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Ambrosetti DC, Schöler HR, Dailey L, Basilico C. Modulation of the activity of multiple transcriptional activation domains by the DNA binding domains mediates the synergistic action of Sox2 and Oct-3 on the fibroblast growth factor-4 enhancer. J Biol Chem 2000; 275:23387-97. [PMID: 10801796 DOI: 10.1074/jbc.m000932200] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Fibroblast growth factor (FGF)-4 gene expression in the inner cell mass of the blastocyst and in EC cells requires the combined activity of two transcriptional regulators, Sox2 and Oct-3, which bind to adjacent sites on the FGF-4 enhancer DNA and synergistically activate transcription. Sox2 and Oct-3 bind cooperatively to the enhancer DNA through their DNA-binding, high mobility group and POU domains, respectively. These two domains, however, are not sufficient to activate transcription. We have analyzed a number of Sox2 and Oct-3 deletion mutants to identify the domains within each protein that contribute to the activity of the Sox2 x Oct-3 complex. Within Oct-3, we have identified two activation domains, the N-terminal AD1 and the C-terminal AD2, that play a role in the activity of the Sox2 x Oct-3 complex. AD1 also displays transcriptional activation functions in the absence of Sox2 while AD2 function was only detected within the Sox2 x Oct-3 complex. In Sox2, we have identified three activation domains within its C terminus: R1, R2, and R3. R1 and R2 can potentiate weak activation by Sox2 in the absence of Oct-3 but their deletion has no effect on the Sox2 x Oct-3 complex. In contrast, R3 function is only observed when Sox2 is complexed with Oct-3. In addition, analysis of Oct-1/Oct-3 chimeras indicates that the Oct-3 homeodomain also plays a critical role in the formation of a functional Sox2 x Oct-3 complex. Our results are consistent with a model in which the synergistic action of Sox2 and Oct-3 results from two major processes. Cooperative binding of the factors to the enhancer DNA, mediated by their binding domains, stably tethers each factor to DNA and increases the activity of intrinsic activation domains within each protein. Protein-protein and protein-DNA interactions then may lead to reciprocal conformational changes that expose latent activation domains within each protein. These findings define a mechanism that may also be utilized by other Sox x POU protein complexes in gene activation.
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Affiliation(s)
- D C Ambrosetti
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
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15
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Nowling TK, Johnson LR, Wiebe MS, Rizzino A. Identification of the transactivation domain of the transcription factor Sox-2 and an associated co-activator. J Biol Chem 2000; 275:3810-8. [PMID: 10660531 DOI: 10.1074/jbc.275.6.3810] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The importance of interactions between Sox and POU transcription factors in the regulation of gene expression is becoming increasingly apparent. Recently, many examples of the involvement of Sox-POU partnerships in transcription have been discovered, including a partnership between Sox-2 and Oct-3. Little is known about the mechanisms by which these factors modulate transcription. To better understand the molecular interactions involved, we mapped the location of the transactivation domain of Sox-2. This was done in the context of its interaction with Oct-3, as well as its ability to transactivate as a fusion protein linked to the DNA-binding domain of Gal4. Both approaches demonstrated that Sox-2 contains a transactivation domain in its C-terminal half, containing a serine-rich region and the C terminus. We also determined that the viral oncoprotein E1a inhibits the ability of the Gal4/Sox-2 fusion protein to transactivate, as well as the transcriptional activation mediated by the combined action of Sox-2 and Oct-3. In contrast, a mutant form of E1a, unable to bind p300, lacks both of these effects. Importantly, we determined that p300 overcomes the inhibitory effects of E1a in both assays. Together, these findings suggest that Sox-2 mediates its effects, at least in part, through the co-activator p300.
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Affiliation(s)
- T K Nowling
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA
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16
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Hildesheim J, Foster RA, Chamberlin ME, Vogel JC. Characterization of the regulatory domains of the human skn-1a/Epoc-1/Oct-11 POU transcription factor. J Biol Chem 1999; 274:26399-406. [PMID: 10473598 DOI: 10.1074/jbc.274.37.26399] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Skn-1a POU transcription factor is primarily expressed in keratinocytes of murine embryonic and adult epidermis. Although some POU factors expressed in a tissue-specific manner are important for normal differentiation, the biological function of Skn-1a remains unknown. Previous in vitro studies indicate that Skn-1a has the ability to transactivate markers of keratinocyte differentiation. In this study, we have characterized Skn-1a's transactivation domain(s) and engineered a dominant negative protein that lacked this transactivation domain. Deletional analysis of the human homologue of Skn-1a with three target promoters revealed the presence of two functional domains: a primary C-terminal transactivation domain and a combined N-terminal inhibitory domain and transactivation domain. Skn-1a lacking the C-terminal region completely lost transactivation ability, irrespective of the promoter tested, and was able to block transactivation by normal Skn-1a in competition assays. Compared with full-length, Skn-1a lacking the N-terminal region demonstrated either increased transactivation (bovine cytokeratin 6 promoter), comparable transactivation (human papillomavirus type 1a long control region), or loss of transactivation (human papillomavirus type 18 long control region). The identification of a primary C-terminal transactivation domain enabled us to generate a dominant negative Skn-1a factor, which will be useful in the quest for a better understanding of this keratinocyte-specific gene regulator.
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Affiliation(s)
- J Hildesheim
- Dermatology Branch, NCI, National Institutes of Health, Bethesda, Maryland 20892-1908, USA
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17
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Schonemann MD, Ryan AK, Erkman L, McEvilly RJ, Bermingham J, Rosenfeld MG. POU domain factors in neural development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1999; 449:39-53. [PMID: 10026784 DOI: 10.1007/978-1-4615-4871-3_4] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Transcription factors serve critical roles in the progressive development of general body plan, organ commitment, and finally, specific cell types. Comparison of the biological roles of a series of individual members within a family permits some generalizations to be made regarding the developmental events that are likely to be regulated by a particular class of transcription factors. Here, we evidence that the developmental functions of the family of transcription factors characterized by the POU DNA binding motif exerts roles in mammalian development. The POU domain family of transcription factors was defined following the observation that the products of three mammalian genes, Pit-1, Oct-1, and Oct-2, and the protein encoded by the C. elegans gene unc-86, shared a region of homology, known as the POU domain. The POU domain is a bipartite DNA binding domain, consisting of two highly conserved regions, tethered by a variable linker. The approximately 75 amino acid N-terminal region was called the POU-specific domain and the C-terminal 60 amino acid region, the POU-homeodomain. High-affinity site-specific DNA binding by POU domain transcription factors requires both the POU-specific and the POU-homeodomain. Resolution of the crystal structures of Oct-1 and Pit-1 POU domains bound to DNA as a monomer and homodimer, respectively, confirmed several of the in vitro findings regarding interactions of this bipartite DNA binding domain with DNA and has provided important information regarding the flexibility and versatility of POU domain proteins. Overall the crystal structure of a monomer of the Oct-1 POU domain bound to the octamer element was similar to that predicted by the NMR solution structures of the POU-specific domain and the POU-homeodomain in isolation, with the POU-specific domain consists of four alpha helices, with the second and third helices forming a structure similar to the helix-turn-helix motif of the lambda and 434 repressors; several of the DNA base contacts are also conserved. A homodimer of the Pit-1 POU domain was crystallized bound to a Pit-1 dimer DNA element that is closely related to a site in the proximal promoter of the prolactin gene. The structure of the Pit-1 POU domain on DNA is very similar to that of Oct-1, and the Pit-1 POU-homeodomain/DNA structure is strikingly similar to that of other homeodomains, including the Oct-1 POU-homeodomain. The DNA contacts made by the Pit-1 POU-specific domain are also similar to those of Oct-1 and conserved with many made by the prokaryotic repressors. In the Oct-1 crystal, the POU-specific domain recognizes a GCAT half-site, while the corresponding sequence recognized by the Pit-1 POU-specific domain, GTAT, is on the opposing strand. As a result, the orientation of the Pit-1 POU-specific domain relative to the POU-homeodomain is flipped, as compared to the Oct-1 crystal structure, indicating the remarkable flexibility of the POU-specific domain in adapting to variations in sequence within the site. Also in contrast to the Oct-1 monomer structure is the observation that the POU-specific and POU-homeodomain of each Pit-1 molecule make major groove contacts on the same face of the DNA, consistent with the constraints imposed by its 15 amino acid linker. As a result, the Pit-1 POU domain homodimer essentially surrounds its DNA binding site. In the Pit-1 POU domain homodimer the dimerization interface is formed between the C-terminal end of helix 3 of the POU-homeodomain of one Pit-1 molecule and the N-terminus of helix 1 and the loop between helices 3 and 4 of the POU-specific domain of the other Pit-1 molecule. In contrast to other homeodomain crystal structures, the C-terminus of helix 3 in the Pit-1 POU-homeo-domain has an extended structure. (ABSTRACT TRUNCATED)
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Affiliation(s)
- M D Schonemann
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego 92093-0648, USA
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18
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Ben-Shushan E, Thompson JR, Gudas LJ, Bergman Y. Rex-1, a gene encoding a transcription factor expressed in the early embryo, is regulated via Oct-3/4 and Oct-6 binding to an octamer site and a novel protein, Rox-1, binding to an adjacent site. Mol Cell Biol 1998; 18:1866-78. [PMID: 9528758 PMCID: PMC121416 DOI: 10.1128/mcb.18.4.1866] [Citation(s) in RCA: 199] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/1997] [Accepted: 01/06/1998] [Indexed: 02/07/2023] Open
Abstract
The Rex-1 (Zfp-42) gene, which encodes an acidic zinc finger protein, is expressed at high levels in embryonic stem (ES) and F9 teratocarcinoma cells. Prior analysis identified an octamer motif in the Rex-1 promoter which is required for promoter activity in undifferentiated F9 cells and is involved in retinoic acid (RA)-associated reduction in expression. We show here that the Oct-3/4 transcription factor, but not Oct-1, can either activate or repress the Rex-1 promoter, depending on the cellular environment. Rex-1 repression is enhanced by E1A. The protein domain required for Oct-3/4 activation was mapped to amino acids 1 to 35, whereas the domain required for Oct-3/4 repression was mapped to amino acids 61 to 126, suggesting that the molecular mechanisms underlying transcriptional activation and repression differ. Like Oct-3/4, Oct-6 can also lower the expression of the Rex-1 promoter via the octamer site, and the amino-terminal portion of Oct-6 mediates this repression. In addition to the octamer motif, a novel positive regulatory element, located immediately 5' of the octamer motif, was identified in the Rex-1 promoter. Mutations in this element greatly reduce Rex-1 promoter activity in F9 cells. High levels of a binding protein(s), designated Rox-1, recognize this novel DNA element in F9 cells, and this binding activity is reduced following RA treatment. Taken together, these results indicate that the Rex-1 promoter is regulated by specific octamer family members in early embryonic cells and that a novel element also contributes to Rex-1 expression.
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Affiliation(s)
- E Ben-Shushan
- Hubert H. Humphrey Center for Experimental Medicine and Cancer Research, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
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19
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Tomilin A, Vorob'ev V, Drosdowsky M, Séralini GE. Oct3/4-associating proteins from embryonal carcinoma and spermatogenic cells of mouse. Mol Biol Rep 1998; 25:103-9. [PMID: 9540071 DOI: 10.1023/a:1006846225844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The octamer-binding protein Oct3/4 was postulated to active transcription through protein-protein interactions with hypothetical cellular coactivator(s). We have used a bacterially produced Oct3/4, as a protein-binding probe, to detect by far-Western assay the Oct3/4-associating proteins (OTAPs) from the embryonal carcinoma (EC) cells F9 and pachytene spermatocytes. Both common and cell-specific OTAPs were shown to interact directly with Oct3/4. Differentiation of the EC cells results in disappearance of most of OTAPs, supporting their coactivator nature. Several OTAPs detected in pachytene spermatocyte may represent germ cell-specific Oct3/4 coactivators.
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Affiliation(s)
- A Tomilin
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
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20
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Brehm A, Ovitt CE, Schöler HR. Oct-4: more than just a POUerful marker of the mammalian germline? APMIS 1998; 106:114-24; discussion 124-6. [PMID: 9524569 DOI: 10.1111/j.1699-0463.1998.tb01326.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mammals lack visible cytoplasmic components in the oocyte that could account for 'germline determinants' as identified in various non-mammalian species. Actually, mammals might not define the germline autonomously by localized 'germline determinants' but conditionally depending on the position of cells within the embryo. The Oct-4 gene encodes a transcription factor that is specifically expressed in the toti- and pluripotential stem cells of the mouse embryo and so far has only been found in mammalian species. Oct-4-expressing embryonal cell retain the capacity to differentiate along multiple lineages and they have been suggested to be part of a 'totipotent germline cycle' that links one generation to the next.
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Affiliation(s)
- A Brehm
- Gene Expression Programme, EMBL, Heidelberg, Germany
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21
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Ambrosetti DC, Basilico C, Dailey L. Synergistic activation of the fibroblast growth factor 4 enhancer by Sox2 and Oct-3 depends on protein-protein interactions facilitated by a specific spatial arrangement of factor binding sites. Mol Cell Biol 1997; 17:6321-9. [PMID: 9343393 PMCID: PMC232483 DOI: 10.1128/mcb.17.11.6321] [Citation(s) in RCA: 281] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Octamer binding and Sox factors are thought to play important roles in development by potentiating the transcriptional activation of specific gene subsets. The proteins within these factor families are related by the presence of highly conserved DNA binding domains, the octamer binding protein POU domain or the Sox factors HMG domain. We have previously shown that fibroblast growth factor 4 (FGF-4) gene expression in embryonal carcinoma cells requires a synergistic interaction between Oct-3 and Sox2 on the FGF-4 enhancer. Sox2 and Oct-3 bind to adjacent sites within this enhancer to form a ternary protein-DNA complex (Oct-3*) whose assembly correlates with enhancer activity. We now demonstrate that increasing the distance between the octamer and Sox binding sites by base pair insertion results in a loss of enhancer function. Significantly, those enhancer "spacing mutants" which failed to activate transcription were also compromised in their ability to form the Oct* complexes even though they could still bind both Sox2 and the octamer binding proteins, suggesting that a direct interaction between Sox2 and Oct-3 is necessary for enhancer function. Consistent with this hypothesis, Oct-3 and Sox2 can participate in a direct protein-protein interaction in vitro in the absence of DNA, and both this interaction and assembly of the ternary Oct* complexes require only the octamer protein POU and Sox2 HMG domains. Assembly of the ternary complex by these two protein domains occurs in a cooperative manner on FGF-4 enhancer DNA, and the loss of this cooperative interaction contributes to the defect in Oct-3* formation observed for the enhancer spacing mutants. These observations indicate that Oct-3* assembly results from protein-protein interactions between the domains of Sox2 and Oct-3 that mediate their binding to DNA, but it also requires a specific arrangement of the binding sites within the FGF-4 enhancer DNA. Thus, these results define one parameter that is fundamental to synergistic activation by Sox2 and Oct-3 and further emphasize the critical role of enhancer DNA sequences in the proper assembly of functional activation complexes.
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Affiliation(s)
- D C Ambrosetti
- Department of Microbiology and Kaplan Cancer Center, New York University School of Medicine, New York 10016, USA
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22
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Ryan AK, Rosenfeld MG. POU domain family values: flexibility, partnerships, and developmental codes. Genes Dev 1997; 11:1207-25. [PMID: 9171367 DOI: 10.1101/gad.11.10.1207] [Citation(s) in RCA: 404] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- A K Ryan
- Howard Hughes Medical Institute, Department and School of Medicine, University of California at San Diego, La Jolla 92093-0648, USA
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23
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Terunuma A, Shiba K, Noda T. A novel genetic system to isolate a dominant negative effector on DNA-binding activity of Oct-2. Nucleic Acids Res 1997; 25:1984-90. [PMID: 9115366 PMCID: PMC146677 DOI: 10.1093/nar/25.10.1984] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Recent studies have revealed that interactions between transcription factors play an important role in regulation of gene expression in eukaryotic cells. To isolate cDNA clones that dominantly inhibit the DNA-binding activity of Oct-2, chosen as a representative factor, we have developed a novel screening system. This employs an Escherichia coli tester strain carrying a modified lac operon as a reporter gene, with the lac operator sequence replaced by an octamer sequence. Oct-2 expressed in this tester strain represses the expression of the reporter gene and changes the phenotype of the cell from Lac+to Lac-. Introduction of a cDNA expression library prepared from a human T-cell line into the Oct-2-harboring tester strain allowed selection of three Lac+clones out of 1 x 10(5) transformants. One of them, hT86, encoding a putative zinc finger protein was found to derepress beta-galactosidase activity in the Oct-2-harboring tester strain at the transcriptional level. In gel mobility shift assays, hT86 attenuated the intensity of the retarded band composed of the octamer probe and Oct-2, suggesting a dominant negative effect on the DNA-binding activity of Oct-2. The strategy described here provides a new approach for studying protein-protein interactions that govern the complex regulation of gene expression.
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Affiliation(s)
- A Terunuma
- Department of Cell Biology, The Cancer Institute, Japanese Foundation for Cancer Research, Kami-Ikebukuro, Toshima-ku, Tokyo 170, Japan
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24
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Brehm A, Ohbo K, Schöler H. The carboxy-terminal transactivation domain of Oct-4 acquires cell specificity through the POU domain. Mol Cell Biol 1997; 17:154-62. [PMID: 8972195 PMCID: PMC231739 DOI: 10.1128/mcb.17.1.154] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The POU transcription factor Oct-4 is expressed in totipotent and pluripotent cells of the early mouse embryo and the germ cell lineage. Transactivation capacities of regions flanking the DNA binding domain of Oct-4 were analyzed in undifferentiated and differentiated cell lines. The amino- and carboxy-terminal regions (N domain and C domain) fused to the Gal4 DNA binding domain both functioned as transactivation domains in all cell lines tested. However, the C domain failed to activate transcription in some cell lines in the context of the native protein. The underlying regulatory mechanism appears to involve the POU domain of Oct-4 and can discriminate between different POU domains, since constructs in which the C domain was instead fused to the POU domain of Pit-1 were again equally active in all cell lines. These results indicate that the C domain is subject to cell-type-specific regulation mediated by the Oct-4 POU domain. Phosphopeptide analysis revealed that the cell-type-specific difference of C-domain activity correlates with a difference in Oct-4 phosphorylation status. Since Oct-4 is expressed in a variety of distinct cell types during murine embryogenesis, these results suggest an additional regulatory mechanism for determining Oct-4 function in rapidly changing cell types during development.
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Affiliation(s)
- A Brehm
- Gene Expression Programme, EMBL, Heidelberg, Germany
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25
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Vigano MA, Staudt LM. Transcriptional activation by Oct-3: evidence for a specific role of the POU-specific domain in mediating functional interaction with Oct-1. Nucleic Acids Res 1996; 24:2112-8. [PMID: 8668543 PMCID: PMC145896 DOI: 10.1093/nar/24.11.2112] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Oct-3, a member of the POU family of transcription factors, is expressed in pluripotent cells of early mammalian embryos and in undifferentiated embryonal carcinoma cell lines. Using a variety of Oct-3 mutants, we have identified two different domains of Oct-3 which activate transcription in transfected mammalian cells. One of these domains, located in the C-terminal part of the protein, plays a major role in transcriptional activation when Oct-3 is bound to its cognate site, the octamer motif. An Oct-3 mutant containing a single amino acid substitution in the POU homeodomain is unable to bind the octamer target in vitro, yet is still able to activate transcription in an octamer-dependent manner. We provide evidence that transactivation by this mutant involves protein-protein interactions with the ubiquitous octamer binding factor Oct-1. This interaction requires the POU-specific domain of Oct-3 and allows recruitment of Oct-3 to the target promoter even in the absence of Oct-3 DNA binding.
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Affiliation(s)
- M A Vigano
- DIBIT-Istituto Scientifico H.S. Raffaele, Milano, Italy
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26
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Morita EH, Shirakawa M, Hayashi F, Imagawa M, Kyogoku Y. Structure of the Oct-3 POU-homeodomain in solution, as determined by triple resonance heteronuclear multidimensional NMR spectroscopy. Protein Sci 1995; 4:729-39. [PMID: 7613470 PMCID: PMC2143109 DOI: 10.1002/pro.5560040412] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The POU-homeodomain (POUH) forms the bipartite DNA-binding POU domain in association with the POU-specific domain. The 1H, 15N, and 13C magnetic resonances of the 67-amino acid long POUH of mouse Oct-3 have almost completely been assigned, mainly through the combined use of three-dimensional triple resonance NMR methods. Based on the distance and dihedral angle constraints derived from the NMR data, the solution structure of the POUH domain has been calculated by the ab initio simulated annealing method. The average RMS deviation for all backbone heavy atoms of the 20 best calculated structures for residues 9-53 of the total 67 amino acid residues is 0.44 A. The POUH domain consists of three alpha-helices (helix-I, 10-20; helix-II, 28-38; and helix-III, 42-53), and helices-II and -III form a helix-turn-helix motif. In comparison with other classical homeodomains, the folding of the three helices is quite similar. However, the length of helix-III is fairly short. In the complex of the Oct-1 POU domain with an octamer site (Klemm JD, et al., 1994, Cell 77:21-32), the corresponding region is involved in helix-III. The structural difference between these two cases will be discussed.
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Affiliation(s)
- E H Morita
- Institute for Protein Research, Osaka University, Japan
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27
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Abstract
Wiskott-Aldrich syndrome (WAS) is an X-linked recessive immunodeficiency characterized by eczema, thrombocytopenia, and recurrent infections. Linkage studies have placed the gene at Xp11.22-p11.23. We have isolated from this interval a novel gene, WASP, which is expressed in lymphocytes, spleen, and thymus. The gene is not expressed in two unrelated WAS patients, one of whom has a single base deletion that produces a frame shift and premature termination of translation. Two additional patients have been identified with point mutations that change the same arginine residue to either a histidine or a leucine. WASP encodes a 501 amino acid proline-rich protein that is likely to be a key regulator of lymphocyte and platelet function.
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Affiliation(s)
- J M Derry
- Howard Hughes Medical Institute, Beckman Center for Molecular and Genetic Medicine, Stanford, California
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28
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Andersen B, Schonemann M, Pearse RV, Jenne K, Sugarman J, Rosenfeld M. Brn-5 is a divergent POU domain factor highly expressed in layer IV of the neocortex. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)49475-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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29
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Wegner M, Drolet DW, Rosenfeld MG. POU-domain proteins: structure and function of developmental regulators. Curr Opin Cell Biol 1993; 5:488-98. [PMID: 8352967 DOI: 10.1016/0955-0674(93)90015-i] [Citation(s) in RCA: 207] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
POU-domain proteins are a group of developmental regulators found in organisms as distant as worm and man. The sequence conservation of the POU-domain has allowed the characterization of increasing numbers of proteins containing the domain, many of which act to control the generation and maintenance of differentiated cell phenotypes in organs as diverse as skin and brain. Analysis of the means by which POU-domain proteins regulate transcription has led to a further understanding of how this group initiates specific developmental programs.
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Affiliation(s)
- M Wegner
- Howard Hughes Medical Institute, University of California, San Diego, School of Medicine, La Jolla 92093-0648
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30
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Verrijzer CP, Van der Vliet PC. POU domain transcription factors. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1173:1-21. [PMID: 8485147 DOI: 10.1016/0167-4781(93)90237-8] [Citation(s) in RCA: 205] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- C P Verrijzer
- Laboratory for Physiological Chemistry, University of Utrecht, The Netherlands
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31
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Morita EH, Shirakawa M, Hayashi F, Imagawa M, Kyogoku Y. Secondary structure of the oct-3 POU homeodomain as determined by 1H-15N NMR spectroscopy. FEBS Lett 1993; 321:107-10. [PMID: 8097478 DOI: 10.1016/0014-5793(93)80088-c] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Most of the 1H and 15N magnetic resonances of the 66 amino acid long POU homeodomain of mouse Oct-3 have been assigned by the combined use of the two-dimensional homonuclear, and two- and three-dimensional heteronuclear NMR methods. The sequential NOE connectivities and amide proton exchange measurements indicate the presence of three helical regions within the domain. The positions of the three helices correspond well to those of other homeodomains, the three-dimensional structures of which have already been determined. The present NMR study provides the first experimental evidence for the existence of a helix-turn-helix motif in the oct-3 POU homeodomain.
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Affiliation(s)
- E H Morita
- Institute for Protein Research, Osaka University, Japan
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32
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Meijer D, Graus A, Grosveld G. Mapping the transactivation domain of the Oct-6 POU transcription factor. Nucleic Acids Res 1992; 20:2241-7. [PMID: 1594443 PMCID: PMC312337 DOI: 10.1093/nar/20.9.2241] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The POU transcription factor Oct-6 is expressed in embryonic stem cells, glial progenitor cells and in a restricted set of neurons in the CNS. The protein has been shown to act as a transactivator as well as a repressor. Here we show that the Oct-6 protein activates transcription from three different promoters in HeLa cells. The ability to activate a minimal tk promoter via a multimerized IgH enhancer octamer motif relies on a domain within the aminoterminal third of the protein. Parts of this domain can be deleted without abolishing transactivation, suggesting that there is functional redundancy within this region. The transactivation domain of the Oct-6 protein is different from other described activation domains in that it is highly glycine and alanine rich.
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Affiliation(s)
- D Meijer
- MGC, Department of Cell Biology and Genetics, Erasmus University, Rotterdam, The Netherlands
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