Shakson Isaac, Douglas Dubosky, Ashley Waldron, Natsuko Emura, Aidan Furze, Kavya Rao, Masaru Mori, Ashok Ragavendran, Hideki Makinoshima and Mamiko Yajima : Unique metabolic regulation of micromeres contributes to gastrulation in the sea urchin embryo., Nature Communications, 16, 1, 2025.
(要約)
During development, a group of cells called organizers plays critical roles by sending signals to adjacent cells and controlling embryonic and tissue patterning. Recent studies suggest that these inductive cells facilitate the downstream signaling pathways conserved across organisms. However, what makes these cells fundamentally inductive is little understood. In this study, we demonstrate that the micromeres of the sea urchin, one of the known organizers, have distinct metabolic properties compared to the rest of the embryo. The specific metabolic inhibitors for sugar metabolism (2-DG), fatty acid synthesis (cerulenin), and N-linked glycosylation (tunicamycin) compromise micromeres' regulatory capacity, altering the downstream germ layer patterning in the resultant embryos. Notably, the endoplasmic reticulum (ER) asymmetrically localizes during asymmetric cell division, resulting in the enrichment of ER and Wnt protein at the vegetal cortex of micromeres. Metabolic inhibition appears to compromise ER activity in Wnt particle distribution. We propose that the micromere ER is sensitive to specific metabolic regulation, contributing to the inductive signaling activity. This study provides a paradigm of how ER and metabolic regulation contribute to the inductive capability of the cells.
Mariana Witmer, Nirali Mehta, Natsuko Emura and Mamiko Yajima : Germline factors, TDRD and Piwi, colocalize with Vasa on the mitotic apparatus during the embryogenesis of the sea urchin., Developmental Biology, 527, 98-108, 2025.
(要約)
Germline factors are thought to function exclusively in the germline, providing the unique characteristics of germ cells. However, recent studies suggest that some of these factors may also be expressed and function outside the germline. One such example includes Vasa, a DEAD-box RNA helicase that appears to control localized translation on the spindle, facilitating efficient protein synthesis during embryogenesis of the sea urchin. However, it remains unclear if other germline factors are also involved in this process. In this study, we investigated the localization dynamics of Vasa's partners in the germline, such as Tudor-domain-containing proteins (TDRDs) and P-element-induced wimpy testis proteins (Piwis). Among TDRDs tested in this study, we found that TDRD7 is enriched on the spindle and forms granules with Vasa during early embryogenesis. Vasa and TDRD7 recruited each other when the expression of either was forced at the membrane, suggesting their interaction with each other. TDRD7 mutants lacking the N-terminal eLOTUS domain or the central intrinsically disordered region exhibited reduced granule formation, which also compromised their recruitment to Vasa. In contrast, PiwiL1/2 and PiwiL3 showed enrichment at the perinuclear region and the spindle, yet were never recruited to Vasa or TDRD7 when either was expressed at the membrane. These results suggest that a group of germline factors is present and may dynamically interact with each other on the spindle, contributing to somatic cell regulation in the sea urchin embryo.
Natsuko Emura, M Florence D Wavreil, Annaliese Fries and Mamiko Yajima : The evolutionary modifications of a GoLoco motif in the AGS protein facilitate micromere formation in the sea urchin embryo., eLife, 13, 2024.
(要約)
The evolutionary introduction of asymmetric cell division (ACD) into the developmental program facilitates the formation of a new cell type, contributing to developmental diversity and, eventually, species diversification. The micromere of the sea urchin embryo may serve as one of those examples: an ACD at the 16-cell stage forms micromeres unique to echinoids among echinoderms. We previously reported that a polarity factor, activator of G-protein signaling (AGS), plays a crucial role in micromere formation. However, AGS and its associated ACD factors are present in all echinoderms and across most metazoans. This raises the question of what evolutionary modifications of AGS protein or its surrounding molecular environment contributed to the evolutionary acquisition of micromeres only in echinoids. In this study, we learned that the GoLoco motifs at the AGS C-terminus play critical roles in regulating micromere formation in sea urchin embryos. Further, other echinoderms' AGS or chimeric AGS that contain the C-terminus of AGS orthologs from various organisms showed varied localization and function in micromere formation. In contrast, the sea star or the pencil urchin orthologs of other ACD factors were consistently localized at the vegetal cortex in the sea urchin embryo, suggesting that AGS may be a unique variable factor that facilitates ACD diversity among echinoderms. Consistently, sea urchin AGS appears to facilitate micromere-like cell formation and accelerate the enrichment timing of the germline factor Vasa during early embryogenesis of the pencil urchin, an ancestral type of sea urchin. Based on these observations, we propose that the molecular evolution of a single polarity factor facilitates ACD diversity while preserving the core ACD machinery among echinoderms and beyond during evolution.
Natsuko Emura, Yuriko Saito, Ruri Miura and Ken Sawai : Effect of Downregulating the Hippo Pathway Members YAP1 and LATS2 Transcripts on Early Development and Gene Expression Involved in Differentiation in Porcine Embryos., Cellular Reprogramming, 22, 2, 62-70, 2020.
(要約)
In mouse development, differentiation of the inner cell mass (ICM) and trophectoderm (TE) during the transition from the morula to blastocyst stage is regulated by the Hippo pathway; however, the functions of the Hippo pathway in porcine embryogenesis have not been investigated. In the present study, we examined the gene expression patterns of the Hippo pathway members yes-associated protein 1 (YAP1) and large tumor suppressor 2 (LATS2) and the functions of these genes during porcine preimplantation development using RNA interference. Both YAP1 and LATS2 mRNA levels were shown high in the in vitro matured oocytes and 1-cell stage embryos and fell progressively with development. YAP1 nuclear localization was detected at the morula and blastocyst stages. Downregulation of either YAP1 or LATS2 inhibited porcine preimplantation development and affected the expression levels of POU class 5 homeobox 1 (OCT-4) and SRY-related HMG-box gene 2 (SOX2), transcription factors necessary for the ICM/TE differentiation. Taken together, YAP1 and LATS2 are essential for porcine preimplantation development, and it is possible that the Hippo pathway has important roles in porcine ICM/TE segregation.
(キーワード)
Adaptor Proteins, Signal Transducing / Animals / Blastocyst Inner Cell Mass / Cell Differentiation / Down-Regulation / Embryo Culture Techniques / Embryonic Development / Fertilization in Vitro / Gene Expression Regulation, Developmental / Octamer Transcription Factor-3 / Protein Serine-Threonine Kinases / RNA Interference / SOXB1 Transcription Factors / Signal Transduction / Swine
Natsuko Emura, Chiung-Min Wang, Harry William Yang and Wei-Hsiung Yang : Steroidogenic Factor 1 (NR5A1) Activates ATF3 Transcriptional Activity., International Journal of Molecular Sciences, 21, 4, 2020.
(要約)
Steroidogenic Factor 1 (SF-1/NR5A1), an orphan nuclear receptor, is important for sexual differentiation and the development of multiple endocrine organs, as well as cell proliferation in cancer cells. Activating transcription factor 3 (ATF3) is a transcriptional repressor, and its expression is rapidly induced by DNA damage and oncogenic stimuli. Since both NR5A1 and ATF3 can regulate and cooperate with several transcription factors, we hypothesized that NR5A1 may interact with ATF3 and plays a functional role in cancer development. First, we found that NR5A1 physically interacts with ATF3. We further demonstrated that ATF3 expression is up-regulated by NR5A1. Moreover, the promoter activity of the ATF3 is activated by NR5A1 in a dose-dependent manner in several cell lines. By mapping the ATF3 promoter as well as the site-directed mutagenesis analysis, we provide evidence that NR5A1 response elements (-695 bp and -665 bp) are required for ATF3 expression by NR5A1. It is well known that the transcriptional activities of NR5A1 are modulated by post-translational modifications, such as small ubiquitin-related modifier (SUMO) modification and phosphorylation. Notably, we found that both SUMOylation and phosphorylation of NR5A1 play roles, at least in part, for NR5A1-mediated ATF3 expression. Overall, our results provide the first evidence of a novel relationship between NR5A1 and ATF3.
Natsuko Emura, Kazuki Takahashi, Yuriko Saito and Ken Sawai : The necessity of TEAD4 for early development and gene expression involved in differentiation in porcine embryos., The Journal of Reproduction and Development, 65, 4, 361-368, 2019.
(要約)
TEA domain family transcription factor 4 (Tead4) is known to be important for the trophectoderm (TE) segregation in murine embryos. However, the role of TEAD4 in early development of porcine embryos is still unknown. We examined TEAD4 expression patterns and attempted to determine the functions of TEAD4 during porcine preimplantation development using RNA interference. TEAD4 mRNA was upregulated from the 2-4-cell to 8-16-cell stages and then decreased to the blastocyst stage. Nuclear localization of TEAD4 protein was detected at the 16-cell stage, as well as at subsequent developmental stages. In porcine embryos injected with TEAD4 siRNA, transformation from morula to blastocyst was inhibited. Although TEAD4 downregulation did not affect the expression levels of POU class 5 homeobox 1 (OCT-4), transcription of SRY-related HMG-box gene 2 (SOX2) was detected at high level in TEAD4-downregulated embryos. It is possible that TEAD4 contributes to blastocyst formation in porcine embryos through downregulation of SOX2 expression. Collectively, our results indicate that TEAD4 is an important factor for the preimplantation development of porcine embryos.
Nobuyuki Sakurai, Kazuki Takahashi, Natsuko Emura, Tsutomu Hashizume and Ken Sawai : Effects of downregulating TEAD4 transcripts by RNA interference on early development of bovine embryos., The Journal of Reproduction and Development, 63, 2, 135-142, 2016.
(要約)
Transcription factor TEA domain family transcription factor 4 (Tead4) is one of the key factors involved in the differentiation of the trophectoderm (TE) in murine embryos. However, knowledge on the roles of TEAD4 in preimplantation development during bovine embryos is currently limited. This study examined the transcript and protein expression patterns of TEAD4 and attempted to elucidate the functions of TEAD4 during bovine preimplantation development using RNA interference. TEAD4 mRNA was found to be upregulated between the 16-cell and morula stages, and nuclear localization of the TEAD4 protein was detected at the morula stage, as well as in subsequent developmental stages. TEAD4 downregulation did not affect embryonic development until the blastocyst stage, and TEAD4-downregulated embryos were capable of forming the TE under both 5% and 21% O2 conditions. Results of gene expression analysis showed that TEAD4 downregulation did not affect the expression levels of POU class 5 transcription factor 1 (OCT-4), NANOG, caudal-type homeobox 2 (CDX2), GATA binding protein 3 (GATA3), and interferon-tau (IFNT). In conclusion, TEAD4 might be dispensable for development until the blastocyst stage and TE differentiation in bovine embryos.
Nobuyuki Sakurai, Kazuki Takahashi, Natsuko Emura, Takashi Fujii, Hiroki Hirayama, Soichi Kageyama, Tsutomu Hashizume and Ken Sawai : The Necessity of OCT-4 and CDX2 for Early Development and Gene Expression Involved in Differentiation of Inner Cell Mass and Trophectoderm Lineages in Bovine Embryos., Cellular Reprogramming, 18, 5, 309-318, 2016.
(要約)
The functions of POU class 5 transcription factor 1 (Oct-4) and caudal-type homeobox 2 (Cdx2) in the differentiation of the murine inner cell mass (ICM) and trophectoderm (TE) have been described in detail. However, little is known about the roles of OCT-4 and CDX2 in preimplantation bovine embryos. To elucidate their functions during early development in bovine embryos, we performed OCT-4 and CDX2 downregulation using RNA interference. We injected OCT-4- or CDX2-specific short interfering RNAs (siRNAs) into bovine zygotes. The rate of blastocyst development of OCT-4-downregulated embryos was lower compared with uninjected or control siRNA-injected embryos. Gene expression analysis revealed decreased CDX2 and fibroblast growth factor 4 expression in OCT-4-downregulated embryos. CDX2-downregulated embryos developed to the blastocyst stage; however, in most cases, blastocoel formation was delayed. Gene expression analysis revealed decreased GATA3 expression and elevated NANOG expression in CDX2-downregulated embryos. In conclusion, OCT-4 and CDX2 are essential for early development and gene expression involved in differentiation of ICM and TE lineages in bovine embryos.
Natsuko Emura, Nobuyuki Sakurai, Kazuki Takahashi, Tsutomu Hashizume and Ken Sawai : OCT-4 expression is essential for the segregation of trophectoderm lineages in porcine preimplantation embryos., The Journal of Reproduction and Development, 62, 4, 401-408, 2016.
(要約)
Oct-4, a member of the POU family of transcription factors, is a key factor that regulates the segregation of the inner cell mass (ICM) and the trophectoderm (TE) during the transition from morula to blastocyst in mice. However, little is known about its role in porcine early embryogenesis. To determine the function of OCT-4 in the ICM and TE segregation of porcine embryos, we studied the developmental morphology of porcine embryos using RNA interference technology. Our experiments demonstrated that when 1-cell stage embryos were co-injected with the small interfering RNA (siRNA)for targeted knockdown of OCT-4 (OCT-4-siRNA) and tetramethylrhodamine isothiocyanate (TRITC)-dextran conjugate (Dx), they failed to form blastocysts. Therefore, in this study, we constructed chimeric embryos comprising blastomeres that either expressed OCT-4 normally or showed downregulated OCT-4 expression by co-injection of OCT-4-siRNA and Dx into one blastomere in 2- to 4-cell stage embryos. In control embryos, which were co-injected with control siRNA and Dx, Dx-positive cells contributed to the TE lineage in almost all the blastocysts examined. In contrast, Dx-positive cells derived from a blastomere co-injected with OCT-4-siRNA and Dx were degenerated in almost half the blastocysts. This was probably due to the inability of these cells to differentiate into the TE lineage. Real-time RT-PCR analysis revealed no difference in the levels of SOX2, TEAD4, FGF4 and FGFR1-IIIc, all of which are known to be regulated by OCT-4, between the OCT-4-siRNA-injected morulae and the control ones. However, the level of CDX2, a molecule specifically expressed in the TE lineage, was significantly higher in the former than in the latter. Our results indicate that continuous expression of OCT-4 in blastomeres is essential for TE formation of porcine embryos.
Kazuki Takahashi, Nobuyuki Sakurai, Natsuko Emura, Tsutomu Hashizume and Ken Sawai : Effects of downregulating GLIS1 transcript on preimplantation development and gene expression of bovine embryos., The Journal of Reproduction and Development, 61, 5, 369-374, 2015.
(要約)
Krüppel-like protein Gli-similar 1 (GLIS1) is known as a direct reprogramming factor for the generation of induced pluripotent stem cells. The objective of this study was to investigate the role of GLIS1 in the preimplantation development of bovine embryos. GLIS1 transcripts in in vitro-matured oocytes and 1-cell to 4-cell stage embryos were detected, but they were either absent or at trace levels at the 8-cell to blastocyst stages. We attempted GLIS1 downregulation of bovine early embryos by RNA interference and evaluated developmental competency and gene transcripts, which are involved in zygotic gene activation (ZGA) in GLIS1-downregulated embryos. Injection of specific siRNA resulted in a distinct decrease in GLIS1 transcript in bovine embryos at the 4-cell stage. Although the bovine embryos injected with GLIS1-siRNA could develop to the 16-cell stage, these embryos had difficulty in developing beyond the 32-cell stage. Gene transcripts of PDHA1 and HSPA8, which are transcribed after ZGA, showed lower level in GLIS1 downregulated embryos. It is possible that GLIS1-downregulated embryos fail to initiate ZGA. Our results indicated that GLIS1 is an important factor for the preimplantation development of bovine embryos.
Natsuko Emura and Mamiko Yajima : Micromere formation and its evolutionary implications in the sea urchin., Current Topics in Developmental Biology, 146, 211-238, Dec. 2021.
(要約)
The micromeres of the sea urchin embryo are distinct from other blastomeres. After they arise through an asymmetric cell division at the 8- to 16-cell stage, micromeres immediately function as organizers. They also commit themselves to specific cell fates such as larval skeletogenic cells and primordial germ cells, while other blastomeres remain plastic and uncommitted at the 16-cell stage. In the phylum Echinodermata, only the sea urchin (class Echinoidea) embryo forms micromeres that serve as apparent organizers during early embryogenesis. Therefore, it is considered that micromeres are the derived features and that modification(s) of the developmental system allowed evolutionary introduction of this unique cell lineage. In this chapter, we summarize the both historic and recent observations that demonstrate unique properties of micromeres and discuss how this lineage of micromeres may have arisen during echinoderm evolution.
Natsuko Emura, M Florence D Wavreil, Annaliese Fries and Mamiko Yajima : The evolutionary modifications of a GoLoco motif in the AGS protein facilitate micromere formation in the sea urchin embryo, Society for Developmental Biology 83rd Annual Meeting, Jul. 2024.
2.
Mariana Witmer, Natsuko Emura and Mamiko Yajima : The granule dynamics of Vasa during early sea urchin embryogenesis, 2024 SDB Northeast Regional Meeting, Apr. 2024.
3.
Jennifer Cheng, Natsuko Emura and Mamiko Yajima : YAP plays a critical role in spindle dynamics during early embryogenesis of the sea urchin, 2024 SDB Northeast Regional Meeting, Apr. 2024.
4.
Natsuko Emura, M Florence D Wavreil and Mamiko Yajima : Evolutionary introduction of the micromere through modifications of the AGS protein, Developmental Biology of Sea Urchins and other Marine Invertebrates XXVI, Apr. 2022.
5.
Natsuko Emura, Shiho Kusanagi, Yuriko Saito, Ruri Miura and Ken Sawai : Effect of fatty acids on early development of bovine preimplantation embryos, Society for the Study of Reproduction, 52nd Annual Meeting, Jul. 2019.
6.
Yuriko Saito, Ayako Sasaki, Natsuko Emura, Ruri Miura and Ken Sawai : Effect of downregulating AGO1 transcripts by RNA interference on early development of porcine embryos, Society for the Study of Reproduction, 52nd Annual Meeting, Jul. 2019.
7.
Natsuko Emura, Kazuki Takahashi, Senga Toma, Shuto Minagawa, Yuriko Saito, Tsutomu Hashizume and Ken Sawai : Effects of downregulating YAP1 transcripts by RNA interference on early development of porcine embryos, Society for the Study of Reproduction, 51st Annual Meeting, Jul. 2018.
8.
Natsuko Emura and Wei-Hsiung Yang : SF-1 regulates ATF3 expression, Society for the Study of Reproduction, 50th Annual Meeting 20177, Jul. 2017.
9.
Natsuko Emura, Nobuyuki Sakurai, Kazuki Takahashi, Tsutomu Hashizume and Ken Sawai : The necessity of OCT-4 expression for the segregation of trophectoderm lineages in porcine preimplantation embryos, 17th AAAP (Asian Australasian Animal Production) Animal Science Congress, Aug. 2016.
10.
Kazuki Takahashi, Nobuyuki Sakurai, Natsuko Emura, Tsutomu Hashizume and Ken Sawai : Effect of downregulating ZSCAN4 transcript on early development and gene expression of bovine embryos, 17th AAAP (Asian Australasian Animal Production) Animal Science Congress, Aug. 2016.
11.
Nobuyuki Sakurai, Kazuki Takahashi, Natsuko Emura, Tsutomu Hashizume and Ken Sawai : Effects of downregulating OCT-4 and CDX2 transcripts on early development and gene expression in bovine embryos, International Conference on Biology and Pathology of Reproduction in Domestic Animals, Sep. 2015.
国内講演発表:
1.
Natsuko Emura, Manaka Noguchi and Tatsuya Takemoto : Impact of differences in Wnt signaling output levels on cell differentiation during gastrulation in the mouse embryo, The 59th Annual Meeting of the Japanese Society of Developmental Biologists, Jun. 2026.
2.
Manaka Noguchi, Natsuko Emura and Tatsuya Takemoto : Elucidation of the role of Eomes in mesoderm differentiation during embryonic development, The 59th Annual Meeting of the Japanese Society of Developmental Biologists, Jun. 2026.