The Neo-X Does Not Form a Barr Body but Shows a Slightly Condensed Structure in the Okinawa Spiny Rat (Tokudaia muenninki).

IF 1.7 4区 生物学 Q4 CELL BIOLOGY
Cytogenetic and Genome Research Pub Date : 2022-01-01 Epub Date: 2023-06-02 DOI:10.1159/000531275
Ryoma Kudo, Ikuya Yoshida, Luisa Matiz Ceron, Shusei Mizushima, Yoko Kuroki, Takamichi Jogahara, Asato Kuroiwa
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Abstract

X chromosome inactivation (XCI) is an essential mechanism for gene dosage compensation between male and female cells in mammals. The Okinawa spiny rat (Tokudaia muenninki) is a native rodent in Japan with XX/XY sex chromosomes, like most mammals; however, the X chromosome has acquired a neo-X region (Xp) by fusion with an autosome. We previously reported that dosage compensation has not yet evolved in the neo-X region; however, X-inactive-specific transcript (Xist) RNA (long non-coding RNA required for the initiation of XCI) is partially localized in the region. Here, we show that the neo-X region represents an early chromosomal state in the acquisition of XCI by analyses of heterochromatin and Barr body formation. We found no evidence for heterochromatin formation in the neo-X region by R-banding by acridine orange (RBA) assays and immunostaining of H3K27me3. Double-immunostaining of H3K27me3 and HP1, a component of the Barr body, revealed that the entire ancestral X chromosome region (Xq) showed a bipartite folded structure. By contrast, HP1 was not localized to the neo-X region. However, BAC-FISH revealed that the signals of genes on the neo-X region of the inactive X chromosome were concentrated in a narrow region. These findings indicated that although the neo-X region of the inactive X chromosome does not form a complete Barr body structure (e.g., it lacks HP1), it forms a slightly condensed structure. These findings combined with the previously reported partial binding of Xist RNA suggest that the neo-X region exhibits incomplete inactivation. This may represent an early chromosomal state in the acquisition of the XCI mechanism.

冲绳刺鼠(Tokudaia muenninki)的Neo-X不形成Barr体,但显示出轻微的凝聚结构。
X染色体失活(XCI)是哺乳动物雌雄细胞间基因剂量补偿的重要机制。冲绳刺鼠(Tokudaia muenninki)是日本本土的啮齿动物,与大多数哺乳动物一样,具有XX/XY性染色体;然而,X染色体通过与常染色体融合获得了一个新X区(Xp)。我们以前报道过,剂量补偿尚未在neo-X区发展;然而,X-inactive-specific transcript (Xist) RNA (XCI起始所需的长链非编码RNA)部分定位于该区域。在这里,我们通过分析异染色质和Barr体的形成表明,neo-X区域代表了XCI获得的早期染色体状态。我们通过吖啶橙(RBA)检测和H3K27me3的免疫染色发现,在neo-X区没有异染色质形成的证据。H3K27me3和HP1 (Barr小体的一个组成部分)的双免疫染色显示,整个祖先X染色体区域(Xq)显示出两部分折叠结构。相比之下,HP1不局限于neo-X区。然而,BAC-FISH结果显示,失活X染色体neo-X区的基因信号集中在一个狭窄的区域。这些发现表明,失活X染色体的neo-X区虽然不形成完整的Barr体结构(如缺少HP1),但形成了一个略微凝聚的结构。这些发现与先前报道的Xist RNA的部分结合表明,neo-X区域表现出不完全失活。这可能代表了XCI机制获得的早期染色体状态。
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来源期刊
Cytogenetic and Genome Research
Cytogenetic and Genome Research 生物-细胞生物学
CiteScore
3.10
自引率
5.90%
发文量
25
审稿时长
1 months
期刊介绍: During the last decades, ''Cytogenetic and Genome Research'' has been the leading forum for original reports and reviews in human and animal cytogenetics, including molecular, clinical and comparative cytogenetics. In recent years, most of its papers have centered on genome research, including gene cloning and sequencing, gene mapping, gene regulation and expression, cancer genetics, comparative genetics, gene linkage and related areas. The journal also publishes key papers on chromosome aberrations in somatic, meiotic and malignant cells. Its scope has expanded to include studies on invertebrate and plant cytogenetics and genomics. Also featured are the vast majority of the reports of the International Workshops on Human Chromosome Mapping, the reports of international human and animal chromosome nomenclature committees, and proceedings of the American and European cytogenetic conferences and other events. In addition to regular issues, the journal has been publishing since 2002 a series of topical issues on a broad variety of themes from cytogenetic and genome research.
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