研究実績
2025
8.
Yuriko Yoshimura, Aki Hayashi, Mayo Tanaka, Mieko Suzuki‐Matsubara, Reiko Nakagawa, Gohei Nishibuchi, Hideaki Tagami, Masaya Oki, Jun‐ichi Nakayama
Mitotic Phosphorylation of Swi6/HP1 Regulates Its Chromatin Binding and Chromosome Segregation Journal Article
In: The FASEB Journal, vol. 39, no. 21, 2025, ISSN: 1530-6860.
Abstract | Links | タグ: Nakayama G
@article{Yoshimura2025,
title = {Mitotic Phosphorylation of Swi6/HP1 Regulates Its Chromatin Binding and Chromosome Segregation},
author = {Yuriko Yoshimura and Aki Hayashi and Mayo Tanaka and Mieko Suzuki‐Matsubara and Reiko Nakagawa and Gohei Nishibuchi and Hideaki Tagami and Masaya Oki and Jun‐ichi Nakayama},
doi = {10.1096/fj.202500384r},
issn = {1530-6860},
year = {2025},
date = {2025-11-02},
urldate = {2025-11-15},
journal = {The FASEB Journal},
volume = {39},
number = {21},
publisher = {Wiley},
abstract = {In eukaryotic cells, heterochromatin assembly is critical for chromosome segregation and transcriptional gene silencing. Heterochromatin protein 1 (HP1) is a conserved chromosomal protein that plays an important role in heterochromatin assembly. We have previously shown that mammalian HP1α and Schizosaccharomyces pombe Swi6 are phosphorylated by casein kinase II (CK2) and that this phosphorylation is essential for their function in heterochromatin assembly. In addition to CK2-mediated phosphorylation, several studies have shown that HP1 proteins undergo additional phosphorylation during mitosis. However, functional significance of the mitotic phosphorylation of HP1 remains unclear. Here, we identified mitotic phosphorylation sites within fission yeast Swi6 and showed that this phosphorylation is involved in chromosome segregation. Using an Escherichia coli co-expression system, we showed that Swi6 is phosphorylated by Ark1, a solo Aurora kinase in S. pombe, and mutational analyses revealed that serine residues in the conserved N-terminal region of Swi6 are the primary targets of Ark1. By expressing mutant Swi6, we confirmed that these serine residues are phosphorylated during mitosis in vivo. Although non-phosphorylatable or phosphomimic mutations in Swi6 had little effect on heterochromatic silencing, they caused defects in early chromosome segregation and modulated the temperature-sensitive growth of mutant cells for chromosome passenger complex components. These results suggest that the Ark1-mediated mitotic phosphorylation of Swi6 is involved in chromosome segregation during mitosis and implicates a conserved regulatory role for the mitotic phosphorylation of HP1 proteins.},
keywords = {Nakayama G},
pubstate = {published},
tppubtype = {article}
}
In eukaryotic cells, heterochromatin assembly is critical for chromosome segregation and transcriptional gene silencing. Heterochromatin protein 1 (HP1) is a conserved chromosomal protein that plays an important role in heterochromatin assembly. We have previously shown that mammalian HP1α and Schizosaccharomyces pombe Swi6 are phosphorylated by casein kinase II (CK2) and that this phosphorylation is essential for their function in heterochromatin assembly. In addition to CK2-mediated phosphorylation, several studies have shown that HP1 proteins undergo additional phosphorylation during mitosis. However, functional significance of the mitotic phosphorylation of HP1 remains unclear. Here, we identified mitotic phosphorylation sites within fission yeast Swi6 and showed that this phosphorylation is involved in chromosome segregation. Using an Escherichia coli co-expression system, we showed that Swi6 is phosphorylated by Ark1, a solo Aurora kinase in S. pombe, and mutational analyses revealed that serine residues in the conserved N-terminal region of Swi6 are the primary targets of Ark1. By expressing mutant Swi6, we confirmed that these serine residues are phosphorylated during mitosis in vivo. Although non-phosphorylatable or phosphomimic mutations in Swi6 had little effect on heterochromatic silencing, they caused defects in early chromosome segregation and modulated the temperature-sensitive growth of mutant cells for chromosome passenger complex components. These results suggest that the Ark1-mediated mitotic phosphorylation of Swi6 is involved in chromosome segregation during mitosis and implicates a conserved regulatory role for the mitotic phosphorylation of HP1 proteins.
7.
Rinko Nakamura, Aki Hayashi, Reiko Nakagawa, Yuriko Yoshimura, Naoki Horikoshi, Hitoshi Kurumizaka, Jun-ichi Nakayama
Intrinsically disordered region of Clr4/Suv39 regulates its enzymatic activity and ensures heterochromatin spreading Journal Article
In: Nucleic Acids Research, vol. 53, no. 17, pp. gkaf878, 2025, ISSN: 1362-4962.
Abstract | Links | タグ: Kurumizaka G, Nakayama G
@article{10.1093/nar/gkaf878,
title = {Intrinsically disordered region of Clr4/Suv39 regulates its enzymatic activity and ensures heterochromatin spreading},
author = {Rinko Nakamura and Aki Hayashi and Reiko Nakagawa and Yuriko Yoshimura and Naoki Horikoshi and Hitoshi Kurumizaka and Jun-ichi Nakayama},
url = {https://doi.org/10.1093/nar/gkaf878},
doi = {10.1093/nar/gkaf878},
issn = {1362-4962},
year = {2025},
date = {2025-09-09},
urldate = {2025-01-01},
journal = {Nucleic Acids Research},
volume = {53},
number = {17},
pages = {gkaf878},
abstract = {Methylation of histone H3 at lysine 9 (H3K9me), a hallmark of heterochromatin, is catalyzed by Clr4/Suv39. Clr4/Suv39 contains two conserved domains—an N-terminal chromodomain and a C-terminal catalytic domain—connected by an intrinsically disordered region (IDR). Several mechanisms have been proposed to regulate Clr4/Suv39 activity, but how it is regulated under physiological conditions remains largely unknown. We found that the N-terminus of Clr4 interacts with its C-terminal catalytic domain and represses its enzymatic activity. Detailed biochemical analyses revealed that basic amino acid residues in the IDR are involved in this interaction. Amino acid substitutions of these residues weakened this interaction, thereby promoting Clr4 activity in vitro. Interestingly, cells expressing mutant Clr4 with these substitutions showed a silencing defect, which suggested additional roles of the IDR in vivo. Genetic analysis revealed that the IDR functions in H3K9me spreading and that this activity is functionally linked to the RNAi pathway. We also showed that Clr4 binds to RNAs via the IDR and that RNA attenuates Clr4 autoinhibition in vitro. Furthermore, the IDR was found to contribute to the targeting of nucleosomal substrates in vitro. These results reveal a novel function of the Clr4/Suv39 IDR in regulating its enzymatic activity and heterochromatin spreading.},
keywords = {Kurumizaka G, Nakayama G},
pubstate = {published},
tppubtype = {article}
}
Methylation of histone H3 at lysine 9 (H3K9me), a hallmark of heterochromatin, is catalyzed by Clr4/Suv39. Clr4/Suv39 contains two conserved domains—an N-terminal chromodomain and a C-terminal catalytic domain—connected by an intrinsically disordered region (IDR). Several mechanisms have been proposed to regulate Clr4/Suv39 activity, but how it is regulated under physiological conditions remains largely unknown. We found that the N-terminus of Clr4 interacts with its C-terminal catalytic domain and represses its enzymatic activity. Detailed biochemical analyses revealed that basic amino acid residues in the IDR are involved in this interaction. Amino acid substitutions of these residues weakened this interaction, thereby promoting Clr4 activity in vitro. Interestingly, cells expressing mutant Clr4 with these substitutions showed a silencing defect, which suggested additional roles of the IDR in vivo. Genetic analysis revealed that the IDR functions in H3K9me spreading and that this activity is functionally linked to the RNAi pathway. We also showed that Clr4 binds to RNAs via the IDR and that RNA attenuates Clr4 autoinhibition in vitro. Furthermore, the IDR was found to contribute to the targeting of nucleosomal substrates in vitro. These results reveal a novel function of the Clr4/Suv39 IDR in regulating its enzymatic activity and heterochromatin spreading.
6.
Ting Cheng, Jiachen Zhang, Haicheng Li, Jinghan Diao, Wenxin Zhang, Junhua Niu, Takayuki Kawaguchi, Jun-ichi Nakayama, Kensuke Kataoka, Shan Gao
Identification and characterization of the de novo methyltransferases for eukaryotic N 6 -methyladenine (6mA) Journal Article
In: Sci. Adv., vol. 11, no. 20, 2025, ISSN: 2375-2548.
Abstract | Links | タグ: Nakayama G
@article{Cheng2025,
title = {Identification and characterization of the de novo methyltransferases for eukaryotic \textit{N} ^{6} -methyladenine (6mA)},
author = {Ting Cheng and Jiachen Zhang and Haicheng Li and Jinghan Diao and Wenxin Zhang and Junhua Niu and Takayuki Kawaguchi and Jun-ichi Nakayama and Kensuke Kataoka and Shan Gao},
doi = {10.1126/sciadv.adq4623},
issn = {2375-2548},
year = {2025},
date = {2025-05-16},
urldate = {2025-05-16},
journal = {Sci. Adv.},
volume = {11},
number = {20},
publisher = {American Association for the Advancement of Science (AAAS)},
abstract = {N6-methyladenine (6mA) is an intensively investigated epigenetic modification in eukaryotes. 6mA is maintained through semiconservative transmission during DNA replication, but the identity of de novo methyltransferase (MTase) catalyzing its establishment remains unknown. Here, we identified MT-A70 family proteins AMT2 and AMT5 as the de novo MTases responsible for 6mA establishment, using the unique sexual reproduction process of the unicellular eukaryote Tetrahymena thermophila. Deletion of AMT2 and AMT5 led to a substantial decrease in 6mA levels in the progeny macronucleus, resulting in an altered gene expression pattern and a substantial decline in the survival rate of sexual progenies. Additionally, the maintenance MTase AMT1 could exhibit a much diminished de novo methylation activity in cells lacking AMT2 and AMT5. Our study delineated the establishment-maintenance pathway of 6mA and underscored the biological importance of de novo methylation, revealing a notable parallel between 6mA and the classical 5-methylcytosine in eukaryotes.},
keywords = {Nakayama G},
pubstate = {published},
tppubtype = {article}
}
N6-methyladenine (6mA) is an intensively investigated epigenetic modification in eukaryotes. 6mA is maintained through semiconservative transmission during DNA replication, but the identity of de novo methyltransferase (MTase) catalyzing its establishment remains unknown. Here, we identified MT-A70 family proteins AMT2 and AMT5 as the de novo MTases responsible for 6mA establishment, using the unique sexual reproduction process of the unicellular eukaryote Tetrahymena thermophila. Deletion of AMT2 and AMT5 led to a substantial decrease in 6mA levels in the progeny macronucleus, resulting in an altered gene expression pattern and a substantial decline in the survival rate of sexual progenies. Additionally, the maintenance MTase AMT1 could exhibit a much diminished de novo methylation activity in cells lacking AMT2 and AMT5. Our study delineated the establishment-maintenance pathway of 6mA and underscored the biological importance of de novo methylation, revealing a notable parallel between 6mA and the classical 5-methylcytosine in eukaryotes.
5.
Ayako Furukawa, Kento Yonezawa, Tatsuki Negami, Yuriko Yoshimura, Aki Hayashi, Jun-ichi Nakayama, Naruhiko Adachi, Toshiya Senda, Kentaro Shimizu, Tohru Terada, Nobutaka Shimizu, Yoshifumi Nishimura
A dynamic structural unit of phase-separated heterochromatin protein 1α as revealed by integrative structural analyses Journal Article
In: vol. 53, no. 6, 2025, ISSN: 1362-4962.
Abstract | Links | タグ: Nakayama G
@article{Furukawa2025,
title = {A dynamic structural unit of phase-separated heterochromatin protein 1α as revealed by integrative structural analyses},
author = {Ayako Furukawa and Kento Yonezawa and Tatsuki Negami and Yuriko Yoshimura and Aki Hayashi and Jun-ichi Nakayama and Naruhiko Adachi and Toshiya Senda and Kentaro Shimizu and Tohru Terada and Nobutaka Shimizu and Yoshifumi Nishimura},
doi = {10.1093/nar/gkaf154},
issn = {1362-4962},
year = {2025},
date = {2025-03-20},
urldate = {2025-03-20},
volume = {53},
number = {6},
publisher = {Oxford University Press (OUP)},
abstract = {<jats:title>Abstract</jats:title>
<jats:p>The heterochromatin protein HP1α consists of an N-terminal disordered tail (N-tail), chromodomain (CD), hinge region (HR), and C-terminal chromo shadow domain (CSD). While CD binds to the lysine9-trimethylated histone H3 (H3K9me3) tail in nucleosomes, CSD forms a dimer bridging two nucleosomes with H3K9me3. Phosphorylation of serine residues in the N-tail enhances both H3K9me3 binding and liquid–liquid phase separation (LLPS) by HP1α. We have used integrative structural methods, including nuclear magnetic resonance, small-angle X-ray scattering (SAXS), and multi-angle-light scattering combined with size-exclusion chromatography, and coarse-grained molecular dynamics simulation with SAXS, to probe the HP1α dimer and its CSD deletion monomer. We show that dynamic intra- and intermolecular interactions between the N-tails and basic segments in CD and HR depend on N-tail phosphorylation. While the phosphorylated HP1α dimer undergoes LLPS via the formation of aggregated multimers, the N-tail phosphorylated mutant without CSD still undergoes LLPS, but its structural unit is a dynamic intermolecular dimer formed via the phosphorylated N-tail and a basic segment at the CD end. Furthermore, we reveal that mutation of this basic segment in HP1α affects the size of heterochromatin foci in cultured mammalian cells, suggesting that this interaction plays an important role in heterochromatin formation in vivo.</jats:p>},
keywords = {Nakayama G},
pubstate = {published},
tppubtype = {article}
}
<jats:title>Abstract</jats:title>
<jats:p>The heterochromatin protein HP1α consists of an N-terminal disordered tail (N-tail), chromodomain (CD), hinge region (HR), and C-terminal chromo shadow domain (CSD). While CD binds to the lysine9-trimethylated histone H3 (H3K9me3) tail in nucleosomes, CSD forms a dimer bridging two nucleosomes with H3K9me3. Phosphorylation of serine residues in the N-tail enhances both H3K9me3 binding and liquid–liquid phase separation (LLPS) by HP1α. We have used integrative structural methods, including nuclear magnetic resonance, small-angle X-ray scattering (SAXS), and multi-angle-light scattering combined with size-exclusion chromatography, and coarse-grained molecular dynamics simulation with SAXS, to probe the HP1α dimer and its CSD deletion monomer. We show that dynamic intra- and intermolecular interactions between the N-tails and basic segments in CD and HR depend on N-tail phosphorylation. While the phosphorylated HP1α dimer undergoes LLPS via the formation of aggregated multimers, the N-tail phosphorylated mutant without CSD still undergoes LLPS, but its structural unit is a dynamic intermolecular dimer formed via the phosphorylated N-tail and a basic segment at the CD end. Furthermore, we reveal that mutation of this basic segment in HP1α affects the size of heterochromatin foci in cultured mammalian cells, suggesting that this interaction plays an important role in heterochromatin formation in vivo.</jats:p>
<jats:p>The heterochromatin protein HP1α consists of an N-terminal disordered tail (N-tail), chromodomain (CD), hinge region (HR), and C-terminal chromo shadow domain (CSD). While CD binds to the lysine9-trimethylated histone H3 (H3K9me3) tail in nucleosomes, CSD forms a dimer bridging two nucleosomes with H3K9me3. Phosphorylation of serine residues in the N-tail enhances both H3K9me3 binding and liquid–liquid phase separation (LLPS) by HP1α. We have used integrative structural methods, including nuclear magnetic resonance, small-angle X-ray scattering (SAXS), and multi-angle-light scattering combined with size-exclusion chromatography, and coarse-grained molecular dynamics simulation with SAXS, to probe the HP1α dimer and its CSD deletion monomer. We show that dynamic intra- and intermolecular interactions between the N-tails and basic segments in CD and HR depend on N-tail phosphorylation. While the phosphorylated HP1α dimer undergoes LLPS via the formation of aggregated multimers, the N-tail phosphorylated mutant without CSD still undergoes LLPS, but its structural unit is a dynamic intermolecular dimer formed via the phosphorylated N-tail and a basic segment at the CD end. Furthermore, we reveal that mutation of this basic segment in HP1α affects the size of heterochromatin foci in cultured mammalian cells, suggesting that this interaction plays an important role in heterochromatin formation in vivo.</jats:p>
4.
Chikashi Obuse, Jun-ichi Nakayama
Functional involvement of RNAs and intrinsically disordered proteins in the assembly of heterochromatin Journal Article
In: Biochimica et Biophysica Acta (BBA) - General Subjects, 2025, ISSN: 0304-4165.
Links | タグ: Nakayama G
@article{Obuse2025,
title = {Functional involvement of RNAs and intrinsically disordered proteins in the assembly of heterochromatin},
author = {Chikashi Obuse and Jun-ichi Nakayama},
doi = {10.1016/j.bbagen.2025.130790},
issn = {0304-4165},
year = {2025},
date = {2025-03-06},
journal = {Biochimica et Biophysica Acta (BBA) - General Subjects},
publisher = {Elsevier BV},
keywords = {Nakayama G},
pubstate = {published},
tppubtype = {article}
}
3.
Tomoyuki Oya, Mayo Tanaka, Aki Hayashi, Yuriko Yoshimura, Rinko Nakamura, Kyohei Arita, Yota Murakami, Jun‐ichi Nakayama
In: The FASEB Journal, vol. 39, no. 4, 2025, ISSN: 0892-6638.
Abstract | Links | タグ: Nakayama G
@article{10.1096/fj.202402264RR,
title = {Characterization of the Swi6/HP1 binding motif in its partner protein reveals the basis for the functional divergence of the HP1 family proteins in fission yeast},
author = {Tomoyuki Oya and Mayo Tanaka and Aki Hayashi and Yuriko Yoshimura and Rinko Nakamura and Kyohei Arita and Yota Murakami and Jun‐ichi Nakayama},
doi = {10.1096/fj.202402264RR},
issn = {0892-6638},
year = {2025},
date = {2025-02-13},
urldate = {2025-01-01},
journal = {The FASEB Journal},
volume = {39},
number = {4},
abstract = {The heterochromatin protein 1 (HP1) family recognizes lysine 9‐methylated histone H3 (H3K9me) and recruits other transacting factors to establish higher order chromatin structures. In the fission yeast Schizosaccharomyces pombe (S. pombe), two HP1 family proteins, Swi6 and Chp2, play distinct roles in recruiting transacting factors: Swi6 primarily recruits Epe1, a Jumonji C domain‐containing protein involved in histone H3K9 demethylation, whereas Chp2 recruits Mit1, a component of the Snf2/Hdac Repressive Complex. However, detailed mechanisms of how multiple HP1 family proteins and their respective interactors work cooperatively or exclusively to form higher order chromatin structures remain elusive. In this study, we investigated the interactions between Swi6 and Epe1. We found that Swi6 interacts with Epe1 through its chromoshadow domain, and identified a unique motif, named the FVI motif, in Epe1 involved in this interaction through detailed mapping of the region. Enhanced green fluorescent protein (EGFP) tethering assays showed that the FVI motif is sufficient to recruit ectopically expressed EGFP to heterochromatic regions, and mutational analyses revealed that conserved hydrophobic residues in this motif are essential for proper targeting. Structural simulations further supported the importance of these residues in Swi6 binding. Interestingly, Mit1 containing the Epe1 FVI motif was recruited to the heterochromatic regions by Swi6 but not by Chp2. Cells expressing mutant Mit1 maintained heterochromatic silencing even in chp2∆ cells, suggesting that Chp2 is not required for heterochromatin formation when Mit1 is recruited by Swi6. These findings highlight distinct HP1‐binding motifs in interactors, contributing to functional divergence among HP1 family proteins. In fission yeast, two HP1 proteins, Swi6 and Chp2, play nonoverlapping roles by recruiting distinct binding partners. We have investigated the interactions between Swi6 and Epe1 and identified a unique motif, the FVI motif, in Epe1 that is involved in this interaction. Interestingly, cells expressing mutant Mit1 containing the Epe1 FVI motif maintained proper heterochromatic silencing even in chp2∆ cells. These results provide mechanistic insights into the division of labor among the HP1 family proteins.},
keywords = {Nakayama G},
pubstate = {published},
tppubtype = {article}
}
The heterochromatin protein 1 (HP1) family recognizes lysine 9‐methylated histone H3 (H3K9me) and recruits other transacting factors to establish higher order chromatin structures. In the fission yeast Schizosaccharomyces pombe (S. pombe), two HP1 family proteins, Swi6 and Chp2, play distinct roles in recruiting transacting factors: Swi6 primarily recruits Epe1, a Jumonji C domain‐containing protein involved in histone H3K9 demethylation, whereas Chp2 recruits Mit1, a component of the Snf2/Hdac Repressive Complex. However, detailed mechanisms of how multiple HP1 family proteins and their respective interactors work cooperatively or exclusively to form higher order chromatin structures remain elusive. In this study, we investigated the interactions between Swi6 and Epe1. We found that Swi6 interacts with Epe1 through its chromoshadow domain, and identified a unique motif, named the FVI motif, in Epe1 involved in this interaction through detailed mapping of the region. Enhanced green fluorescent protein (EGFP) tethering assays showed that the FVI motif is sufficient to recruit ectopically expressed EGFP to heterochromatic regions, and mutational analyses revealed that conserved hydrophobic residues in this motif are essential for proper targeting. Structural simulations further supported the importance of these residues in Swi6 binding. Interestingly, Mit1 containing the Epe1 FVI motif was recruited to the heterochromatic regions by Swi6 but not by Chp2. Cells expressing mutant Mit1 maintained heterochromatic silencing even in chp2∆ cells, suggesting that Chp2 is not required for heterochromatin formation when Mit1 is recruited by Swi6. These findings highlight distinct HP1‐binding motifs in interactors, contributing to functional divergence among HP1 family proteins. In fission yeast, two HP1 proteins, Swi6 and Chp2, play nonoverlapping roles by recruiting distinct binding partners. We have investigated the interactions between Swi6 and Epe1 and identified a unique motif, the FVI motif, in Epe1 that is involved in this interaction. Interestingly, cells expressing mutant Mit1 containing the Epe1 FVI motif maintained proper heterochromatic silencing even in chp2∆ cells. These results provide mechanistic insights into the division of labor among the HP1 family proteins.
2024
2.
Da‐Qiao Ding, Kasumi Okamasa, Yuriko Yoshimura, Atsushi Matsuda, Takaharu G. Yamamoto, Yasushi Hiraoka, Jun‐ichi Nakayama
In: The FASEB Journal, vol. 38, no. 21, 2024, ISSN: 1530-6860.
Abstract | Links | タグ: Nakayama G
@article{Ding2024,
title = {Proteins and noncoding <scp>RNAs</scp> that promote homologous chromosome recognition and pairing in fission yeast meiosis undergo condensate formation in vitro},
author = {Da‐Qiao Ding and Kasumi Okamasa and Yuriko Yoshimura and Atsushi Matsuda and Takaharu G. Yamamoto and Yasushi Hiraoka and Jun‐ichi Nakayama},
doi = {10.1096/fj.202302563rr},
issn = {1530-6860},
year = {2024},
date = {2024-11-15},
urldate = {2024-11-15},
journal = {The FASEB Journal},
volume = {38},
number = {21},
publisher = {Wiley},
abstract = {<jats:title>Abstract</jats:title><jats:p>Pairing of homologous chromosomes during meiosis is crucial for successful sexual reproduction. Previous studies have shown that the fission yeast <jats:italic>sme2</jats:italic> RNA, a meiosis‐specific long noncoding RNA (lncRNA), accumulates at the <jats:italic>sme2</jats:italic> locus and plays a key role in mediating robust pairing during meiosis. Several RNA‐binding proteins accumulate at the <jats:italic>sme2</jats:italic> and other lncRNA gene loci in conjunction with the lncRNAs transcribed from these loci. These lncRNA‐protein complexes form condensates that exhibit phase separation properties on chromosomes and are necessary for robust pairing of homologous chromosomes. To further understand the mechanisms by which phase separation affects homologous chromosome pairing, we conducted an in vitro phase separation assay with the <jats:italic>sme2</jats:italic> RNA‐associated proteins (Smps) and RNAs. Our findings reveal that one of the Smps, Seb1, forms condensates resembling phase separation; the observed number and size of these condensates increase upon the addition of another Smp, Rhn1, and purified RNAs. Additionally, we have found that RNAs protect Smp condensates from treatment with 1,6‐hexanediol. The Smp condensates containing different types of RNA display distinct FRAP profiles, and the Smp condensates containing the same type of RNA tend to fuse together more readily than those containing different types of RNAs. Collectively, these results indicate that the specific RNA species within condensates modulate their physical properties, potentially enabling the formation of regional RNA‐Smp condensates with distinct characteristics that facilitate homologous chromosome pairing.</jats:p>},
keywords = {Nakayama G},
pubstate = {published},
tppubtype = {article}
}
<jats:title>Abstract</jats:title><jats:p>Pairing of homologous chromosomes during meiosis is crucial for successful sexual reproduction. Previous studies have shown that the fission yeast <jats:italic>sme2</jats:italic> RNA, a meiosis‐specific long noncoding RNA (lncRNA), accumulates at the <jats:italic>sme2</jats:italic> locus and plays a key role in mediating robust pairing during meiosis. Several RNA‐binding proteins accumulate at the <jats:italic>sme2</jats:italic> and other lncRNA gene loci in conjunction with the lncRNAs transcribed from these loci. These lncRNA‐protein complexes form condensates that exhibit phase separation properties on chromosomes and are necessary for robust pairing of homologous chromosomes. To further understand the mechanisms by which phase separation affects homologous chromosome pairing, we conducted an in vitro phase separation assay with the <jats:italic>sme2</jats:italic> RNA‐associated proteins (Smps) and RNAs. Our findings reveal that one of the Smps, Seb1, forms condensates resembling phase separation; the observed number and size of these condensates increase upon the addition of another Smp, Rhn1, and purified RNAs. Additionally, we have found that RNAs protect Smp condensates from treatment with 1,6‐hexanediol. The Smp condensates containing different types of RNA display distinct FRAP profiles, and the Smp condensates containing the same type of RNA tend to fuse together more readily than those containing different types of RNAs. Collectively, these results indicate that the specific RNA species within condensates modulate their physical properties, potentially enabling the formation of regional RNA‐Smp condensates with distinct characteristics that facilitate homologous chromosome pairing.</jats:p>
1.
Takayuki Kawaguchi, Michihiro Hashimoto, Reiko Nakagawa, Ryunosuke Minami, Masahito Ikawa, Jun-ichi Nakayama, Jun Ueda
Comprehensive posttranslational modifications in the testis-specific histone variant H3t protein validated in tagged knock-in mice Journal Article
In: Scientific Reports, vol. 14, no. 1, pp. 21305, 2024.
Abstract | Links | タグ: Nakayama G
@article{10.1038/s41598-024-72362-7,
title = {Comprehensive posttranslational modifications in the testis-specific histone variant H3t protein validated in tagged knock-in mice},
author = {Takayuki Kawaguchi and Michihiro Hashimoto and Reiko Nakagawa and Ryunosuke Minami and Masahito Ikawa and Jun-ichi Nakayama and Jun Ueda},
doi = {10.1038/s41598-024-72362-7},
year = {2024},
date = {2024-09-12},
urldate = {2024-01-01},
journal = {Scientific Reports},
volume = {14},
number = {1},
pages = {21305},
abstract = {During the development of multicellular organisms and cell differentiation, the chromatin structure in the cell nucleus undergoes extensive changes, and the nucleosome structure is formed by a combination of various histone variants. Histone variants with diverse posttranslational modifications are known to play crucial roles in different regulatory functions. We have previously reported that H3t, a testis-specific histone variant, is essential for spermatogenesis. To elucidate the function of this chromatin molecule in vivo, we generated knock-in mice with a FLAG tag attached to the carboxyl terminus of H3t. In the present study, we evaluated the utility of the generated knock-in mice and comprehensively analyzed posttranslational modifications of canonical H3 and H3t using mass spectrometry. Herein, we found that H3t-FLAG was incorporated into spermatogonia and meiotic cells in the testes, as evidenced by immunostaining of testicular tissue. According to the mass spectrometry analysis, the overall pattern of H3t-FLAG posttranslational modification was comparable to that of the control H3, while the relative abundances of certain specific modifications differed between H3t-FLAG and the control bulk H3. The generated knock-in mice could be valuable for analyzing the function of histone variants in vivo.},
keywords = {Nakayama G},
pubstate = {published},
tppubtype = {article}
}
During the development of multicellular organisms and cell differentiation, the chromatin structure in the cell nucleus undergoes extensive changes, and the nucleosome structure is formed by a combination of various histone variants. Histone variants with diverse posttranslational modifications are known to play crucial roles in different regulatory functions. We have previously reported that H3t, a testis-specific histone variant, is essential for spermatogenesis. To elucidate the function of this chromatin molecule in vivo, we generated knock-in mice with a FLAG tag attached to the carboxyl terminus of H3t. In the present study, we evaluated the utility of the generated knock-in mice and comprehensively analyzed posttranslational modifications of canonical H3 and H3t using mass spectrometry. Herein, we found that H3t-FLAG was incorporated into spermatogonia and meiotic cells in the testes, as evidenced by immunostaining of testicular tissue. According to the mass spectrometry analysis, the overall pattern of H3t-FLAG posttranslational modification was comparable to that of the control H3, while the relative abundances of certain specific modifications differed between H3t-FLAG and the control bulk H3. The generated knock-in mice could be valuable for analyzing the function of histone variants in vivo.
