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  1. Article ; Online: How Germ Cells Determine Their Own Sexual Fate in Mice.

    Saga, Yumiko

    Sexual development : genetics, molecular biology, evolution, endocrinology, embryology, and pathology of sex determination and differentiation

    2022  Volume 16, Issue 5-6, Page(s) 329–341

    Abstract: Background: Whether to produce sperm or eggs is the most basic and important choice from the perspective of germ cell development and differentiation. However, the induction mechanism has not received much attention until relatively recently. This is ... ...

    Abstract Background: Whether to produce sperm or eggs is the most basic and important choice from the perspective of germ cell development and differentiation. However, the induction mechanism has not received much attention until relatively recently. This is because the issue of sexual differentiation has generally been considered a theme of somatic cells to make a testis or ovary. Basically, the sex of individual somatic cells and germ cells matches. Therefore, the sex of germ cells is thought to follow the sex of somatic cells once determined. However, researchers realized that a big, open question remained: What somatic cell signals actually induce the sexual differentiation of germ cells and what is the sex determinant in germ cells?
    Summary: In vitro experiments demonstrated that 2 somatic signals (BMP and RA) act directly on germ cells to induce oogonia. Therefore, these 2 signals may be referred to as oogonia inducers. From the viewpoint of germ cells, an independent experiment identified SMAD4 and STRA8, which are directly downstream of BMP and RA, respectively, acting in germ cells as female determinants. However, what about male? If these factors are female determinants, their absence may result in the induction of spermatogonia. This may be true in vivo because germ cells enter a male pathway if they do not receive these signals even in the ovary. However, this has not been confirmed in an in vitro culture system. There should be signals required for germ cells to enter a male pathway.
    Key messages: The important message is that although testis-specific factors secreted from the testis are considered to include male-inducing factors for germ cells, this may not be the case, and the male-inducing factor, if it exists, also exists in the ovary.
    Language English
    Publishing date 2022-03-09
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 2253672-3
    ISSN 1661-5433 ; 1661-5425
    ISSN (online) 1661-5433
    ISSN 1661-5425
    DOI 10.1159/000520976
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Antagonism between DDX6 and PI3K-AKT signaling is an oocyte-intrinsic mechanism controlling primordial follicle growth†.

    Kato, Yuzuru / Saga, Yumiko

    Biology of reproduction

    2023  Volume 109, Issue 1, Page(s) 73–82

    Abstract: Oocyte maturation and subsequent ovulation during the reproductive lifespan ensure long-term reproduction in mammalian females. This is achieved by tight regulation for the maintenance and growth of primordial follicles. However, the underlying ... ...

    Abstract Oocyte maturation and subsequent ovulation during the reproductive lifespan ensure long-term reproduction in mammalian females. This is achieved by tight regulation for the maintenance and growth of primordial follicles. However, the underlying mechanisms remain unsolved. We herein report that posttranscriptional gene regulation mediated by an RNA helicase, DEAD-box helicase 6 (DDX6), and phosphoinositide-3-kinase (PI3K)-AKT signaling exhibits an antagonistic interaction in mouse primordial follicles. DDX6 forms P-body-like cytoplasmic foci in oocytes, which colocalize to a P-body component, DCP1A. Interestingly, the P-body-like granules predominantly assemble in primordial follicles, but disperse once follicle growth is initiated, suggesting that they play a role in the maintenance of primordial follicles. Oocyte-specific knockout of Ddx6 using Gdf9-iCre revealed that Ddx6-deficient oocytes are defective in foci assembly and are abnormally enlarged, resulting in premature depletion of primordial follicles. These results indicate that DDX6 is required to maintain primordial follicles. The abnormal oocyte enlargement is because of enhanced PI3K-AKT signaling, a pivotal signaling pathway in the growth of primordial follicles. Conversely, the forced activation of PI3K-AKT signaling by knocking out Pten disassembles P-body-like granules in primordial follicles. These data suggest that DDX6 and PI3K-AKT signaling mutually antagonize the assembly of P-body-like granules and the growth of primordial follicles. We propose this mutual antagonism as an oocyte-intrinsic mechanism controlling the maintenance and growth of primordial follicles, ensuring the longevity of female reproduction.
    MeSH term(s) Female ; Mice ; Animals ; Proto-Oncogene Proteins c-akt/metabolism ; Phosphatidylinositol 3-Kinases/metabolism ; Phosphatidylinositol 3-Kinase/metabolism ; Oocytes/metabolism ; Signal Transduction/physiology ; DEAD-box RNA Helicases/genetics ; DEAD-box RNA Helicases/metabolism ; Mammals/metabolism ; Proto-Oncogene Proteins/metabolism
    Chemical Substances Proto-Oncogene Proteins c-akt (EC 2.7.11.1) ; Phosphatidylinositol 3-Kinases (EC 2.7.1.-) ; Phosphatidylinositol 3-Kinase (EC 2.7.1.137) ; DEAD-box RNA Helicases (EC 3.6.4.13) ; Ddx6 protein, mouse (EC 2.7.7.-.) ; Proto-Oncogene Proteins
    Language English
    Publishing date 2023-04-17
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1118-6
    ISSN 1529-7268 ; 0006-3363
    ISSN (online) 1529-7268
    ISSN 0006-3363
    DOI 10.1093/biolre/ioad043
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Repurposing of the enhancer-promoter communication underlies the compensation of Mesp2 by Mesp1.

    Okada, Hajime / Saga, Yumiko

    PLoS genetics

    2022  Volume 18, Issue 1, Page(s) e1010000

    Abstract: Organisms are inherently equipped with buffering systems against genetic perturbations. Genetic compensation, the compensatory response by upregulating another gene or genes, is one such buffering mechanism. Recently, a well-conserved compensatory ... ...

    Abstract Organisms are inherently equipped with buffering systems against genetic perturbations. Genetic compensation, the compensatory response by upregulating another gene or genes, is one such buffering mechanism. Recently, a well-conserved compensatory mechanism was proposed: transcriptional adaptation of homologs under the nonsense-mediated mRNA decay pathways. However, this model cannot explain the onset of all compensatory events. We report a novel genetic compensation mechanism operating over the Mesp gene locus. Mesp1 and Mesp2 are paralogs located adjacently in the genome. Mesp2 loss is partially rescued by Mesp1 upregulation in the presomitic mesoderm (PSM). Using a cultured PSM induction system, we reproduced the compensatory response in vitro and found that the Mesp2-enhancer is required to promote Mesp1. We revealed that the Mesp2-enhancer directly interacts with the Mesp1 promoter, thereby upregulating Mesp1 expression upon the loss of Mesp2. Of note, this interaction is established by genomic arrangement upon PSM development independently of Mesp2 disruption. We propose that the repurposing of this established enhancer-promoter communication is the mechanism underlying this compensatory response for the upregulation of the adjacent gene.
    MeSH term(s) Animals ; Basic Helix-Loop-Helix Transcription Factors/genetics ; Cells, Cultured ; Dosage Compensation, Genetic ; Enhancer Elements, Genetic ; Gene Expression Regulation, Developmental ; Mice ; Nonsense Mediated mRNA Decay ; Promoter Regions, Genetic ; Somites/cytology ; Somites/metabolism
    Chemical Substances Basic Helix-Loop-Helix Transcription Factors ; Mesp1 protein, mouse ; Mesp2 protein, mouse
    Language English
    Publishing date 2022-01-13
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2186725-2
    ISSN 1553-7404 ; 1553-7390
    ISSN (online) 1553-7404
    ISSN 1553-7390
    DOI 10.1371/journal.pgen.1010000
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: A cooperative mechanism of target RNA selection via germ-cell-specific RNA-binding proteins NANOS2 and DND1.

    Hirano, Takamasa / Wright, Danelle / Suzuki, Atsushi / Saga, Yumiko

    Cell reports

    2022  Volume 39, Issue 11, Page(s) 110894

    Abstract: The germ-cell-specific RNA-binding protein (RBP) NANOS2 plays a pivotal role in male gonocyte differentiation and spermatogonial stem cell maintenance. Although NANOS2 interacts with the CNOT deadenylation complex and Dead end 1 (DND1) to repress target ... ...

    Abstract The germ-cell-specific RNA-binding protein (RBP) NANOS2 plays a pivotal role in male gonocyte differentiation and spermatogonial stem cell maintenance. Although NANOS2 interacts with the CNOT deadenylation complex and Dead end 1 (DND1) to repress target RNAs, the molecular mechanisms underlying target mRNA selection remain unclear because of the limited cell resource in vivo. Here, we demonstrate that exogenous NANOS2-DND1 suppresses target mRNAs in somatic cells. Using this somatic cell system, we find that NANOS2 interacts with RNA-bound DND1 and recruits the CNOT complex to the mRNAs. However, a fusion construct composed of the CNOT1-binding site of NANOS2 (NIM) and DND1 fails to repress the target gene expression. Therefore, NANOS2 is required not only for recruitment of the CNOT complex but also for selecting the target mRNA with DND1. This study reveals that NANOS2 functions as a second-layer RBP for the target recognition and functional adaptation of DND1.
    MeSH term(s) Cell Differentiation ; Germ Cells/metabolism ; Humans ; Male ; Neoplasm Proteins/genetics ; Neoplasm Proteins/metabolism ; RNA/metabolism ; RNA, Messenger/genetics ; RNA, Messenger/metabolism ; RNA-Binding Proteins/genetics ; RNA-Binding Proteins/metabolism ; Transcription Factors
    Chemical Substances CNOT1 protein, human ; Dnd1 protein, human ; Dnd1 protein, mouse ; NANOS2 protein, human ; Nanos2 protein, mouse ; Neoplasm Proteins ; RNA, Messenger ; RNA-Binding Proteins ; Transcription Factors ; RNA (63231-63-0)
    Language English
    Publishing date 2022-06-15
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2649101-1
    ISSN 2211-1247 ; 2211-1247
    ISSN (online) 2211-1247
    ISSN 2211-1247
    DOI 10.1016/j.celrep.2022.110894
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: A cooperative mechanism of target RNA selection via germ-cell-specific RNA-binding proteins NANOS2 and DND1

    Takamasa Hirano / Danelle Wright / Atsushi Suzuki / Yumiko Saga

    Cell Reports, Vol 39, Iss 11, Pp 110894- (2022)

    2022  

    Abstract: Summary: The germ-cell-specific RNA-binding protein (RBP) NANOS2 plays a pivotal role in male gonocyte differentiation and spermatogonial stem cell maintenance. Although NANOS2 interacts with the CNOT deadenylation complex and Dead end 1 (DND1) to ... ...

    Abstract Summary: The germ-cell-specific RNA-binding protein (RBP) NANOS2 plays a pivotal role in male gonocyte differentiation and spermatogonial stem cell maintenance. Although NANOS2 interacts with the CNOT deadenylation complex and Dead end 1 (DND1) to repress target RNAs, the molecular mechanisms underlying target mRNA selection remain unclear because of the limited cell resource in vivo. Here, we demonstrate that exogenous NANOS2-DND1 suppresses target mRNAs in somatic cells. Using this somatic cell system, we find that NANOS2 interacts with RNA-bound DND1 and recruits the CNOT complex to the mRNAs. However, a fusion construct composed of the CNOT1-binding site of NANOS2 (NIM) and DND1 fails to repress the target gene expression. Therefore, NANOS2 is required not only for recruitment of the CNOT complex but also for selecting the target mRNA with DND1. This study reveals that NANOS2 functions as a second-layer RBP for the target recognition and functional adaptation of DND1.
    Keywords CP: Molecular biology ; Biology (General) ; QH301-705.5
    Subject code 571
    Language English
    Publishing date 2022-06-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: NANOS3 suppresses premature spermatogonial differentiation to expand progenitors and fine-tunes spermatogenesis in mice.

    Inoue, Hiroki / Sakurai, Takayuki / Hasegawa, Kazuteru / Suzuki, Atsushi / Saga, Yumiko

    Biology open

    2022  Volume 11, Issue 4

    Abstract: In the mouse testis, sperm originate from spermatogonial stem cells (SSCs). SSCs give rise to spermatogonial progenitors, which expand their population until entering the differentiation process that is precisely regulated by a fixed time-scaled program ... ...

    Abstract In the mouse testis, sperm originate from spermatogonial stem cells (SSCs). SSCs give rise to spermatogonial progenitors, which expand their population until entering the differentiation process that is precisely regulated by a fixed time-scaled program called the seminiferous cycle. Although this expansion process of progenitors is highly important, its regulatory mechanisms remain unclear. NANOS3 is an RNA-binding protein expressed in the progenitor population. We demonstrated that the conditional deletion of Nanos3 at a later embryonic stage results in the reduction of spermatogonial progenitors in the postnatal testis. This reduction was associated with the premature differentiation of progenitors. Furthermore, this premature differentiation caused seminiferous stage disagreement between adjacent spermatogenic cells, which influenced spermatogenic epithelial cycles, leading to disruption of the later differentiation pathway. Our study suggests that NANOS3 plays an important role in timing progenitor expansion to adjust to the proper differentiation timing by blocking the retinoic acid (RA) signaling pathway.
    MeSH term(s) Adult Germline Stem Cells/metabolism ; Animals ; Cell Differentiation/genetics ; Male ; Mice ; RNA-Binding Proteins/genetics ; RNA-Binding Proteins/metabolism ; Spermatogenesis/genetics ; Spermatogonia/metabolism ; Testis
    Chemical Substances Nanos3 protein, mouse ; RNA-Binding Proteins
    Language English
    Publishing date 2022-04-08
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2632264-X
    ISSN 2046-6390 ; 2046-6390
    ISSN (online) 2046-6390
    ISSN 2046-6390
    DOI 10.1242/bio.059146
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Decoding the transcriptome of pre-granulosa cells during the formation of primordial follicles in the mouse†.

    Fukuda, Kurumi / Muraoka, Masafumi / Kato, Yuzuru / Saga, Yumiko

    Biology of reproduction

    2021  Volume 105, Issue 1, Page(s) 179–191

    Abstract: Primordial follicles, a finite reservoir of eggs in mammalian ovaries, are composed of a single oocyte and its supporting somatic cells, termed granulosa cells. Although their formation may require reciprocal interplay between oocytes and pre-granulosa ... ...

    Abstract Primordial follicles, a finite reservoir of eggs in mammalian ovaries, are composed of a single oocyte and its supporting somatic cells, termed granulosa cells. Although their formation may require reciprocal interplay between oocytes and pre-granulosa cells, precursors of granulosa cells, little is known about the underlying mechanisms. We addressed this issue by decoding the transcriptome of pre-granulosa cells during the formation of primordial follicles. We found that marked gene expression changes, including extracellular matrix, cell adhesion, and several signaling pathways, occur along with primordial follicle formation. Importantly, differentiation of Lgr5-EGFP-positive pre-granulosa cells to FOXL2-positive granulosa cells was delayed in mutant ovaries of the germ cell-specific genes Nanos3 and Figla, accompanied by perturbed gene expression in mutant pre-granulosa cells. These results suggest that proper development of oocytes is required for the differentiation of pre-granulosa cells. Our data provide a valuable resource for understanding the gene regulatory networks involved in the formation of primordial follicles.
    MeSH term(s) Animals ; Female ; Gene Expression Regulation, Developmental ; Germ Cells/metabolism ; Granulosa Cells/metabolism ; Mice ; Oocytes/metabolism ; Ovarian Follicle/growth & development ; Signal Transduction ; Transcriptome
    Language English
    Publishing date 2021-04-13
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1118-6
    ISSN 1529-7268 ; 0006-3363
    ISSN (online) 1529-7268
    ISSN 0006-3363
    DOI 10.1093/biolre/ioab065
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Genetic and structural analysis of the

    Wright, Danelle / Kiso, Makoto / Saga, Yumiko

    Development (Cambridge, England)

    2021  Volume 148, Issue 1

    Abstract: NANOS2 and NANOS3 are evolutionarily conserved RNA-binding proteins involved in murine germ cell development. NANOS3 is required for protection from apoptosis during migration and gonadal colonization in both sexes, whereas NANOS2 is male-specific and ... ...

    Abstract NANOS2 and NANOS3 are evolutionarily conserved RNA-binding proteins involved in murine germ cell development. NANOS3 is required for protection from apoptosis during migration and gonadal colonization in both sexes, whereas NANOS2 is male-specific and required for the male-type differentiation of germ cells. Ectopic NANOS2 rescues the functions of NANOS3, but NANOS3 cannot rescue NANOS2 function, even though its expression is upregulated in
    MeSH term(s) Amino Acid Sequence ; Animals ; Apoptosis ; Cytoprotection ; Male ; Mice, Knockout ; Neoplasm Proteins/metabolism ; Protein Domains ; RNA-Binding Proteins/chemistry ; RNA-Binding Proteins/genetics ; RNA-Binding Proteins/metabolism ; Recombinant Proteins/metabolism ; Sex Differentiation/genetics ; Spermatozoa/metabolism ; Structure-Activity Relationship ; Zinc Fingers ; Mice
    Chemical Substances Dnd1 protein, mouse ; Nanos2 protein, mouse ; Nanos3 protein, mouse ; Neoplasm Proteins ; RNA-Binding Proteins ; Recombinant Proteins
    Language English
    Publishing date 2021-01-11
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 90607-4
    ISSN 1477-9129 ; 0950-1991
    ISSN (online) 1477-9129
    ISSN 0950-1991
    DOI 10.1242/dev.191916
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  9. Article ; Online: NANOS3 suppresses premature spermatogonial differentiation to expand progenitors and fine-tunes spermatogenesis in mice

    Hiroki Inoue / Takayuki Sakurai / Kazuteru Hasegawa / Atsushi Suzuki / Yumiko Saga

    Biology Open, Vol 11, Iss

    2022  Volume 4

    Abstract: In the mouse testis, sperm originate from spermatogonial stem cells (SSCs). SSCs give rise to spermatogonial progenitors, which expand their population until entering the differentiation process that is precisely regulated by a fixed time-scaled program ... ...

    Abstract In the mouse testis, sperm originate from spermatogonial stem cells (SSCs). SSCs give rise to spermatogonial progenitors, which expand their population until entering the differentiation process that is precisely regulated by a fixed time-scaled program called the seminiferous cycle. Although this expansion process of progenitors is highly important, its regulatory mechanisms remain unclear. NANOS3 is an RNA-binding protein expressed in the progenitor population. We demonstrated that the conditional deletion of Nanos3 at a later embryonic stage results in the reduction of spermatogonial progenitors in the postnatal testis. This reduction was associated with the premature differentiation of progenitors. Furthermore, this premature differentiation caused seminiferous stage disagreement between adjacent spermatogenic cells, which influenced spermatogenic epithelial cycles, leading to disruption of the later differentiation pathway. Our study suggests that NANOS3 plays an important role in timing progenitor expansion to adjust to the proper differentiation timing by blocking the retinoic acid (RA) signaling pathway.
    Keywords nanos3 ; spermatogenesis ; mouse ; retinoic acid ; testis ; Science ; Q ; Biology (General) ; QH301-705.5
    Subject code 571
    Language English
    Publishing date 2022-04-01T00:00:00Z
    Publisher The Company of Biologists
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: NANOS2 suppresses the cell cycle by repressing mTORC1 activators in embryonic male germ cells.

    Shimada, Ryuki / Koike, Hiroko / Hirano, Takamasa / Kato, Yuzuru / Saga, Yumiko

    iScience

    2021  Volume 24, Issue 8, Page(s) 102890

    Abstract: During murine germ cell development, male germ cells enter the mitotically arrested G0 stage, which is an initial step of sexually dimorphic differentiation. The male-specific RNA-binding protein NANOS2 has a key role in suppressing the cell cycle in ... ...

    Abstract During murine germ cell development, male germ cells enter the mitotically arrested G0 stage, which is an initial step of sexually dimorphic differentiation. The male-specific RNA-binding protein NANOS2 has a key role in suppressing the cell cycle in germ cells. However, the detailed mechanism of how NANOS2 regulates the cell cycle remains unclear. Using single-cell RNA sequencing (scRNA-seq), we extracted the cell cycle state of each germ cell in wild-type and
    Language English
    Publishing date 2021-07-22
    Publishing country United States
    Document type Journal Article
    ISSN 2589-0042
    ISSN (online) 2589-0042
    DOI 10.1016/j.isci.2021.102890
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