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Matsuura R, Nakajima T, Ichihara S, Sado T. Ectopic Splicing Disturbs the Function of Xist RNA to Establish the Stable Heterochromatin State. Front Cell Dev Biol 2021; 9:751154. [PMID: 34722536 PMCID: PMC8551810 DOI: 10.3389/fcell.2021.751154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/20/2021] [Indexed: 11/29/2022] Open
Abstract
Non-coding Xist RNA plays an essential role in X chromosome inactivation (XCI) in female mammals. It coats the X chromosome in cis and mediates the recruitment of many proteins involved in gene silencing and heterochromatinization. The molecular basis of how Xist RNA initiates chromosomal silencing and what proteins participate in this process has been extensively studied and elucidated. Its involvement in the establishment and maintenance of the X-inactivated state is, however, less understood. The XistIVS allele we previously reported is peculiar in that it can initiate XCI but fails to establish the inactive state that is stably maintained and, therefore, may provide an opportunity to explore how Xist RNA contributes to establish a robust heterochromatin state. Here we demonstrate that ectopic splicing taking place to produce XistIVS RNA disturbs its function to properly establish stable XCI state. This finding warrants the potential of XistIVS RNA to provide further insight into our understanding of how Xist RNA contributes to establish sustainable heterochromatin.
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Affiliation(s)
- Ruka Matsuura
- Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, Nara, Japan
| | - Tatsuro Nakajima
- Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Saya Ichihara
- Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, Nara, Japan
| | - Takashi Sado
- Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, Nara, Japan.,Agricultural Technology and Innovation Research Institute, Kindai University, Nara, Japan
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Sado T. What makes the maternal X chromosome resistant to undergoing imprinted X inactivation? Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0365. [PMID: 28947661 DOI: 10.1098/rstb.2016.0365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2017] [Indexed: 11/12/2022] Open
Abstract
In the mouse, while either X chromosome is chosen for inactivation in a random fashion in the embryonic tissue, the paternally derived X chromosome is preferentially inactivated in the extraembryonic tissues. It has been shown that the maternal X chromosome is imprinted so as not to undergo inactivation in the extraembryonic tissues. X-linked noncoding Xist RNA becomes upregulated on the X chromosome that is to be inactivated. An antisense noncoding RNA, Tsix, which occurs at the Xist locus and has been shown to negatively regulate Xist expression in cis, is imprinted to be expressed from the maternal X in the extraembryonic tissues. Although Tsix appears to be responsible for the imprint laid on the maternal X, those who disagree with this idea would point out the fact that Tsix has not yet been expressed from the maternal X when Xist becomes upregulated on the paternal but not the maternal X at the onset of imprinted X-inactivation in preimplantation embryos. Recent studies have demonstrated, however, that there is a prominent difference in the chromatin structure at the Xist locus depending on the parental origin, which I suggest might account for the repression of maternal Xist in the absence of maternal Tsix at the preimplantation stages.This article is part of the themed issue 'X-chromosome inactivation: a tribute to Mary Lyon'.
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Affiliation(s)
- Takashi Sado
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan
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Sakata Y, Nagao K, Hoki Y, Sasaki H, Obuse C, Sado T. Defects in dosage compensation impact global gene regulation in the mouse trophoblast. Development 2017; 144:2784-2797. [PMID: 28684628 DOI: 10.1242/dev.149138] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022]
Abstract
Xist RNA, which is responsible for X inactivation, is a key epigenetic player in the embryogenesis of female mammals. Of the several repeats conserved in Xist RNA, the A-repeat has been shown to be essential for its silencing function in differentiating embryonic stem cells. Here, we introduced a new Xist allele into mouse that produces mutated Xist RNA lacking the A-repeat (XistCAGΔ5' ). XistCAGΔ5' RNA expressed in the embryo coated the X chromosome but failed to silence it. Although imprinted X inactivation was substantially compromised upon paternal transmission, allele-specific RNA-seq in the trophoblast revealed that XistCAGΔ5' RNA still retained some silencing ability. Furthermore, the failure of imprinted X inactivation had more significant impacts than expected on genome-wide gene expression. It is likely that dosage compensation is required not only for equalizing X-linked gene expression between the sexes but also for proper global gene regulation in differentiated female somatic cells.
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Affiliation(s)
- Yuka Sakata
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan.,Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Koji Nagao
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Yuko Hoki
- Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hiroyuki Sasaki
- Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Chikashi Obuse
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takashi Sado
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan .,Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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