Researchers Database

sato shigeru

    Cavdiology and Metabolism Associate Professor
Last Updated :2021/11/23

Researcher Information


  • (BLANK)(1995/03 Tohoku University)


J-Global ID

Research Interests

  • Hypoxic responses   Macrophages   Transcription regulation   Organogenesis   Homeobox genes   Gene enhancers   Comparative genomics   Vertebrate evolution   神経堤   Sensory placode   

Research Areas

  • Life sciences / Cell biology
  • Life sciences / Molecular biology
  • Life sciences / Cardiology
  • Life sciences / Pathobiochemistry
  • Life sciences / Otorhinolaryngology
  • Life sciences / Anatomy
  • Life sciences / Evolutionary biology
  • Life sciences / Developmental biology
  • Life sciences / Genetics

Academic & Professional Experience

  • 2020/06 - Today  Jichi Medical UniversityCenter for Molecular Medicine, Division of Cardiology and MetabolismAssociate Professor
  • 2011/04 - Today  Jichi Medical University Graduate School of MedicineAssociate Professor at graduate school (full time)
  • 2011/04 - 2020/05  Jichi Medical UniversityCenter for Molecular Medicine Division of BiologyAssistant Professor
  • 2003/12 - 2011/03  Jichi Medical UniversityCenter for Molecular Medicine, Division of BiologyLecturer (full time)
  • 2002/05 - 2011/03  Jichi Medical University Graduate School of MedicineLecturer at graduate school (full time)
  • 2002/05 - 2003/11  Jichi Medical UniversityCenter for Molecular Medicine, Division of BiologyLecturer (full time)
  • 2000/01 - 2002/04  Jichi Medical UniversityDepartment of BiologyLecturer (full time)
  • 1998/05 - 1999/12  Jichi Medical UniversityDepartment of BiologyAssistant Professor
  • 1996/01 - 1998/04  JSPSPostdoctoral fellow (PD)
  • 1995/07 - 1995/12  Marie Curie Research Institute (UK)Eukaryotic Transcription LaboratoryPostdoctoral Fellow
  • 1995/04 - 1995/06  Tohoku UniversityGraduate School of Science研究生


  • 1989/04 - 1995/03  Tohoku University  Graduate School of Science  Department of Biology
  • 1984/04 - 1989/03  Tohoku University  Faculty of Science  Department of Biology

Association Memberships

  • 日本動物学会   International Society of Developmental Biology   日本発生生物学会   Society for Developmental Biology   

Published Papers

  • Jumpei Terakawa, Vanida A Serna, Devi M Nair, Shigeru Sato, Kiyoshi Kawakami, Sally Radovick, Pascal Maire, Takeshi Kurita
    Cell death and differentiation 27 (12) 3307 - 3320 2020/06 [Refereed][Not invited]
    During female mammal reproductive tract development, epithelial cells of the lower Müllerian duct are committed to become stratified squamous epithelium of the vagina and ectocervix, when the expression of ΔNp63 transcription factor is induced by mesenchymal cells. The absence of ΔNp63 expression leads to adenosis, the putative precursor of vaginal adenocarcinoma. Our previous studies with genetically engineered mouse models have established that fibroblast growth factor (FGF)/mitogen-activated protein kinase (MAPK), bone morphogenetic protein (BMP)/SMAD, and activin A/runt-related transcription factor 1 (RUNX1) signaling pathways are independently required for ΔNp63 expression in Müllerian duct epithelium (MDE). Here, we report that sine oculis homeobox homolog 1 (SIX1) plays a critical role in the activation of ΔNp63 locus in MDE as a downstream transcription factor of mesenchymal signals. In the developing mouse reproductive tract, SIX1 expression was restricted to MDE within the future cervix and vagina. SIX1 expression was totally absent in SMAD4 null MDE and was reduced in RUNX1 null and FGFR2 null MDE, indicating that SIX1 is under the control of vaginal mesenchymal factors: BMP4, activin A and FGF7/10. Furthermore, Six1, Runx1, and Smad4 gene-dose-dependently activated ΔNp63 expression in MDE within the vaginal fornix. Using a mouse model of diethylstilbestrol (DES)-associated vaginal adenosis, we found DES action through epithelial estrogen receptor α (ESR1) inhibits activation of ΔNp63 locus in MDE by transcriptionally repressing SIX1 and RUNX1 in the vaginal fornix.
  • Takahashi M, Tamura M, Sato S, Kawakami K
    Disease models & mechanisms 11 (10) 1754-8403 2018/10 [Refereed][Not invited]
  • Sato S, Furuta Y, Kawakami K
    Developmental dynamics : an official publication of the American Association of Anatomists 247 (1) 250 - 261 1058-8388 2018/01 [Refereed][Not invited]
  • Ikeda K, Takahashi M, Sato S, Igarashi H, Ishizuka T, Yawo H, Arata S, Southard-Smith EM, Kawakami K, Onimaru H
    PloS one 10 (7) e0132475  2015 [Refereed][Not invited]
  • Sato S, Yajima H, Furuta Y, Ikeda K, Kawakami K
    PloS one 10 (8) e0136666  2015 [Refereed][Not invited]
  • Hiroshi Yajima, Makoto Suzuki, Haruki Ochi, Keiko Ikeda, Shigeru Sato, Ken-ichi Yamamura, Hajime Ogino, Naoto Ueno, Kiyoshi Kawakami
    BMC BIOLOGY 12 40  1741-7007 2014/05 [Refereed][Not invited]
    Background: Various senses and sensory nerve architectures of animals have evolved during adaptation to exploit diverse environments. In craniates, the trunk sensory system has evolved from simple mechanosensory neurons inside the spinal cord (intramedullary), called Rohon-Beard (RB) cells, to multimodal sensory neurons of dorsal root ganglia (DRG) outside the spinal cord (extramedullary). The fish and amphibian trunk sensory systems switch from RB cells to DRG during development, while amniotes rely exclusively on the DRG system. The mechanisms underlying the ontogenic switching and its link to phylogenetic transition remain unknown. Results: In Xenopus, Six1 overexpression promoted precocious apoptosis of RB cells and emergence of extramedullary sensory neurons, whereas Six1 knockdown delayed the reduction in RB cell number. Genetic ablation of Six1 and Six4 in mice led to the appearance of intramedullary sensory neuron-like cells as a result of medial migration of neural crest cells into the spinal cord and production of immature DRG neurons and fused DRG. Restoration of SIX1 expression in the neural crest-linage partially rescued the phenotype, indicating the cell autonomous requirements of SIX1 for normal extramedullary sensory neurogenesis. Mouse Six1 enhancer that mediates the expression in DRG neurons activated transcription in Xenopus RB cells earlier than endogenous six1 expression, suggesting earlier onset of mouse SIX1 expression than Xenopus during sensory development. Conclusions: The results indicated the critical role of Six1 in transition of RB cells to DRG neurons during Xenopus development and establishment of exclusive DRG system of mice. The study provided evidence that early appearance of SIX1 expression, which correlated with mouse Six1 enhancer, is essential for the formation of DRG-dominant system in mice, suggesting that heterochronic changes in Six1 enhancer sequence play an important role in alteration of trunk sensory architecture and contribute to the evolution of the trunk sensory system.
  • Kazuya Ono, Tomoko Kita, Shigeru Sato, Paul O'Neill, Siu-Shan Mak, Marie Paschaki, Masataka Ito, Noriko Gotoh, Kiyoshi Kawakami, Yoshiki Sasai, Raj K. Ladher
    PLOS GENETICS 10 (1) e1004118  1553-7390 2014/01 [Refereed][Not invited]
    Inner ear mechanosensory hair cells transduce sound and balance information. Auditory hair cells emerge from a Sox2-positive sensory patch in the inner ear epithelium, which is progressively restricted during development. This restriction depends on the action of signaling molecules. Fibroblast growth factor (FGF) signalling is important during sensory specification: attenuation of Fgfr1 disrupts cochlear hair cell formation; however, the underlying mechanisms remain unknown. Here we report that in the absence of FGFR1 signaling, the expression of Sox2 within the sensory patch is not maintained. Despite the down-regulation of the prosensory domain markers, p27(Kip1), Hey2, and Hes5, progenitors can still exit the cell cycle to form the zone of non-proliferating cells (ZNPC), however the number of cells that form sensory cells is reduced. Analysis of a mutant Fgfr1 allele, unable to bind to the adaptor protein, Frs2/3, indicates that Sox2 maintenance can be regulated by MAP kinase. We suggest that FGF signaling, through the activation of MAP kinase, is necessary for the maintenance of sensory progenitors and commits precursors to sensory cell differentiation in the mammalian cochlea.
  • Shigeru Sato, Keiko Ikeda, Go Shioi, Kazuki Nakao, Hiroshi Yajima, Kiyoshi Kawakami
    DEVELOPMENTAL BIOLOGY 368 (1) 95 - 108 0012-1606 2012/08 [Refereed][Not invited]
    The Six1 homeobox gene plays critical roles in vertebrate organogenesis. Mice deficient for Six1 show severe defects in organs such as skeletal muscle, kidney, thymus, sensory organs and ganglia derived from cranial placodes, and mutations in human Sal cause branchio-oto-renal syndrome, an autosomal dominant developmental disorder characterized by hearing loss and branchial defects. The present study was designed to identify enhancers responsible for the dynamic expression pattern of Six1 during mouse embryogenesis. The results showed distinct enhancer activities of seven conserved non-coding sequences (CNSs) retained in tetrapod Six1 loci. The activities were detected in all cranial placodes (excluding the lens placode), dorsal root ganglia, somites, nephrogenic cord, notochord and cranial mesoderm. The major Six1-expression domains during development were covered by the sum of activities of these enhancers, together with the previously identified enhancer for the pre-placodal region and foregut endoderm. Thus, the eight CNSs identified in a series of our study represent major evolutionarily conserved enhancers responsible for the expression of Six1 in tetrapods. The results also confirmed that chick electroporation is a robust means to decipher regulatory information stored in vertebrate genomes. Mutational analysis of the most conserved placode-specific enhancer, Six1-21, indicated that the enhancer integrates a variety of inputs from Sox, Pax, Fox, Six, Wnt/Lef1 and basic helix-loop-helix proteins. Positive autoregulation of Six1 is achieved through the regulation of Six protein-binding sites. The identified Six1 enhancers provide valuable tools to understand the mechanism of Six1 regulation and to manipulate gene expression in the developing embryo, particularly in the sensory organs. (C) 2012 Elsevier Inc. All rights reserved.
  • Hiroshi Yajima, Norio Motohashi, Yusuke Ono, Shigeru Sato, Keiko Ikeda, Satoru Masuda, Erica Yada, Hironori Kanesaki, Yuko Miyagoe-Suzuki, Shin'ichi Takeda, Kiyoshi Kawakami
    EXPERIMENTAL CELL RESEARCH 316 (17) 2932 - 2944 0014-4827 2010/10 [Refereed][Not invited]
    Muscle satellite cells are essential for muscle growth and regeneration and their morphology, behavior and gene expression have been extensively studied. However, the mechanisms involved in their proliferation and differentiation remain elusive. Six1 and Six4 proteins were expressed in the nuclei of myofibers of adult mice and the numbers of myoblasts positive for Six1 and Six4 increased during regeneration of skeletal muscles. Six1 and Six4 were expressed in quiescent, activated and differentiated muscle satellite cells isolated from adult skeletal muscle. Overexpression of Six4 and Six5 repressed the proliferation and differentiation of satellite cells. Conversely, knockdown of Six5 resulted in augmented proliferation, and that of Six4 inhibited differentiation. Muscle satellite cells isolated from Six4(+/-)Six5(-/-) mice proliferated to higher cell density though their differentiation was not altered. Meanwhile, overproduction of Six1 repressed proliferation and promoted differentiation of satellite cells. In addition, Six4 and Six5 repressed, while Six1 activated myogenin expression, suggesting that the differential regulation of myogenin expression is responsible for the differential effects of Six genes. The results indicated the involvement of Six genes in the behavior of satellite cells and identified Six genes as potential target for manipulation of proliferation and differentiation of muscle satellite cells for therapeutic applications. (C) 2010 Elsevier Inc. All rights reserved.
  • Shigeru Sato, Keiko Ikeda, Go Shioi, Haruki Ochi, Hajime Ogino, Hiroshi Yajima, Kiyoshi Kawakami
    DEVELOPMENTAL BIOLOGY 344 (1) 158 - 171 0012-1606 2010/08 [Refereed][Not invited]
    All cranial sensory organs and sensory neurons of vertebrates develop from cranial placodes. In chick, amphibians and zebrafish, all placodes originate from a common precursor domain, the pre-placodal region (PPR), marked by the expression of Six1/4 and Eya1/2 However, the PPR has never been described in mammals and the mechanism involved in the formation of PPR is poorly defined. Here, we report the expression of Six1 in the horseshoe-shaped mouse ectoderm surrounding the anterior neural plate in a pattern broadly similar to that of non-mammalian vertebrates To elucidate the identity of Six1-positive mouse ectoderm, we searched for enhancers responsible for Six1 expression by in vivo enhancer assays One conserved non-coding sequence. Six1-14, showed specific enhancer activity in the rostral PPR of chick and Xenopus and in the mouse ectoderm These results strongly suggest the presence of PPR in mouse and that it is conserved in vertebrates Moreover, we show the importance of the homeodomain protein-binding sites of Six1-14, the Six1 rostral PPR enhancer, for enhancer activity, and that Dlx5, Msx1 and Pax7 are candidate binding factors that regulate the level and area of Six1 expression, and thereby the location of the PPR Our findings provide critical information and tools to elucidate the molecular mechanism of early sensory development and have implications for the development of sensory precursor/stem cells (C) 2010 Elsevier Inc All rights reserved
  • Tadashi Ishihara, Shigeru Sato, Keiko Ikeda, Hiroshi Yajima, Kiyoshi Kawakami
    DEVELOPMENTAL DYNAMICS 237 (11) 3142 - 3156 1058-8388 2008/11 [Refereed][Not invited]
    Eya1 is a homolog of eyes absent in Drosophila, and essential for various organ formations in vertebrates. Mouse and chick Eya1 shows dynamic expression pattern in early development. We identified ten independent Eya1 enhancers by screening evolutionarily conserved sequences. They exhibited enhancer activities in Hensen's node, neural tube, migrating neural crest cells, otic vesicle, olfactory placode, cranial ganglia, and somites at HH6-17 of chick embryo. The sum of the enhancer activities of the enhancers covers the endogenous expression domains of Eya1 common to chick and mouse. Enhancer activities were also observed in species-specific expression domains such as trigeminal ganglia and brain. Mutational study of one of the enhancers revealed that the enhancer is composed of positive and negative cis-regulatory elements. Thus, we successfully identified a comprehensive group of enhancers around Eya1 locus, which are probably involved in the control of the complex expression pattern of Eya1 in vivo. Developmental Dynamics 237.3142-3156, 2008. (C) 2008 Wiley-Liss, Inc.
  • Tadashi Ishihara, Keiko Ikeda, Shigeru Sato, Hiroshi Yajima, Kiyoshi Kawakami
    GENE EXPRESSION PATTERNS 8 (5) 357 - 367 1567-133X 2008/05 [Refereed][Not invited]
    Eyes absent is essential for compound eye formation in Drosophila. Its mammalian homologues of Eya are involved in the development of sensory organs, skeletal muscles and kidneys. Mutations of EYA1 in human cause branchio-oto-renal syndrome, with abnormalities in branchial derivatives, ear and kidney. For an insight into the function of Eya1 and Eya2 in early development, we performed whole-mount in situ hybridization and compared the expression patterns of these two genes in the developing chick embryos. Eya1 was first expressed in the primitive streak at Hamburger and Hamilton stage 4 (HH4) and appeared in the ectoderm and head mesenchyme distinct from migrating neural crest cells at HH6-HH11. At HH15 and HH17, the olfactory, otic and vagal/nodose placodes and cranial ganglia were positive for Eya1. In contrast, Eya2 was already expressed in the endoderm at HH4, and appeared in the endoderm and prospective placodal region at HH6-HH11. Eya2 expression was observed in pharyngeal clefts and pouches as well as cranial placodes at HH15 and HH17. These results indicate differential expression of Eya1 and Eya2, both spatially and temporally, in chick during early development. The expression patterns are somewhat different from those of other species such as Xenopus, zebrafish and mouse. The results suggest distinct and unique functions for Eya1 and Eya2 in early chick development. (c) 2008 Elsevier B.V. All rights reserved.
  • Keiko Ikeda, Shigeo Ookawara, Shigeru Sato, Zen-ichi Ando, Ryoichiro Kageyama, Kiyoshi Kawakami
    DEVELOPMENTAL BIOLOGY 311 (1) 53 - 68 0012-1606 2007/11 [Refereed][Not invited]
    The olfactory epithelium (OE) is derived from the olfactory placode (OP) during mouse development. At embryonic day (E) 10.0-E10.5, "early neurogenesis" occurs in the OE, which includes production of pioneer neurons that emigrate out of the OE and other early-differentiated neurons. Around E12.5, the OE becomes organized into mature pseudostratified epithelium and shows "established neurogenesis," in which olfactory receptor neurons (ORNs) are differentiated from basal progenitors. Little is known about the molecular pathway of early neurogenesis. The homeodomain protein Six1 is expressed in all OP cells and neurogenic precursors in the OE. Here we show that early neurogenesis is severely disturbed despite the unaltered expression of Mash1 at E10.5 in the Six1-deficient mice (Six1(-/-)). Expression levels of neurogenin1 (Ngn1) and NeuroD are reduced and those of Hes1 and Hes5 are augmented in the OE of Six1(-/-) at E10.5. Pioneer neurons and cellular aggregates, which are derived from the OP/OE and situated in the mesenchyme between the OE and forebrain, are completely absent in Six1(-/-). Moreover, ORN axons and the gonadotropin-releasing hormone-positive neurons fail to extend and migrate to the forebrain, respectively. Our study indicates that Six1 plays critical roles in early neurogenesis by regulating Ngn1, NeuroD, Hes1, and Hes5. (C) 2007 Elsevier Inc. All rights reserved.
  • Mayuko Kumasaka, Shigeru Sato, Ichiro Yajima, Colin R Goding, Hiroaki Yamamoto
    Developmental dynamics : an official publication of the American Association of Anatomists 234 (3) 523 - 34 1058-8388 2005/11 [Refereed][Not invited]
    Mitf is a central regulator of pigment cell development that is essential for the normal development of the melanocyte and retinal pigment epithelium (RPE) lineages. To understand better the role of Mitf, we have used the Xenopus laevis experimental system to allow a rapid examination of the role of Mitf in vivo. Here, we report the function of XlMitfalpha-M on melanophore development and melanization compared with that of Slug that is expressed in neural crest cells. Overexpression of XlMitfalpha-M led to an increase in melanophores that was partly contributed by an increase in Slug-positive cells, indicating that XlMitfalpha-M is a key regulator of melanocyte/melanophore development and melanization. Moreover, overexpression of a dominant-negative form of XlMitfalpha led to a decrease in the number of melanophores and induced abnormal melanoblast migration. We also observed an induction of ectopic RPE and extended RPE by overexpression of XlMitfalpha-M and possible interactions between XlMitfalpha and several eye-related genes essential for normal eye development.
  • Z Ando, S Sato, K Ikeda, K Kawakami
    FEBS JOURNAL 272 (12) 3026 - 3041 1742-464X 2005/06 [Refereed][Not invited]
    Six genes are homologs of Drosophila sine oculis and encode transcription factors that are characterized by a conserved Six domain and homeodomain. Of the six family members (Six1-Six6) in mice, Six1 and Six4 show similar expression patterns during embryogenesis. Six1(-/-) mice show defective formation of various organs such as inner ear, nose, skeletal muscle, kidney and thymus, whereas Six4(-/-) mice show little anomaly in organogenesis. To understand the molecular basis for the differential function of Six1 and Six4 in vivo, we screened target genes of Six1 and Six4 and found that Six1 and Six4 differentially regulated a set of target genes. Gel-retardation assays indicated that the promoter region of one of the targets, sodium-potassium-chloride cotransporter 1 (Slcl2a2), contains multiple Six1-binding sites and one common binding site of Six1 and Six4, suggesting that the DNA-binding specificity of Six1 is distinct from that of Six4. This underlies the differential regulation of common target genes by Six1 and SiA. Furthermore, in situ hybridization demonstrated that the expression of Slc12a2 was reduced in the developing dorsal root ganglia of Six1(-/-)/Six4(-/-) mice, suggesting that Six1 and Six4 regulate S1c12a2 in vivo.
  • ホメオタンパク質Six1と感覚器の形成
    川上潔, 佐藤滋
    実験医学 22 (12) 1702 - 1708 2004/08 [Not refereed][Invited]
  • R Toyoda, A Kasai, S Sato, S Wada, H Saiga, K Ikeo, T Gojobori, T Numakunai, H Yamamoto
    GENE 332 61 - 69 0378-1119 2004/05 [Refereed][Not invited]
    Solitary ascidian tadpole larvae develop two types of black pigment cells in the major sensory organs of the brain. Such pigment cells have been demonstrated to express the melanogenic genes, tyrosinase and Tyrp/TRP (tyrosinase-related protein). To understand the genetic and developmental mechanisms underlying the differentiation of chordate pigment cells, we examined the function of the promoter region of Tyrp/TRP gene, an ascidian (Halocynthia roretzi) tyrosinase family gene. The expression of the gene in pigment cell lineage starts at the early-mid gastrula stages. To identify the transcriptional regulatory region of the gene allowing cell-type-specific expression, a deletion series of the HrTyrp 5' flanking region fused to a lacZ reporter gene was constructed and microinjected into ascidian fertilized eggs. The region of 73 by in HrTyrp was identified as sufficient for expression in pigment cell-precursors of tailbud stage embryos. It is noteworthy that there is no M-box element highly conserved in the promoters for vertebrate tyrosinase family genes such as tyrosinase, Tyrp1/TRP-1 and Tyrp2/TRP-2 (Dct). Although the regulatory system of ascidian pigment-cell development is likely to contain most factors critical to vertebrate pigment-cell development, there might be critical differences in the mode of regulation, such as the developmental timing of interactions of factors, proteins and genes, involved in pigment cell differentiation and pigmentation. (C) 2004 Elsevier B.V. All rights reserved.
  • M Kumasaka, H Sato, S Sato, Yajima, I, H Yamamoto
    DEVELOPMENTAL DYNAMICS 230 (1) 107 - 113 1058-8388 2004/05 [Refereed][Not invited]
    Mitf (gene for microphthalmia-associated transcription factor) encodes a transcription factor of the basic/helix-loop-helix/leucine-zipper family and is a key regulator during the development of two different types of melanin-producing cell lineages, namely neural crest-derived melanocytes/melanophores, and the retinal pigment epithelium (RPE) differentiated from the outer layer of the eye cup. Mitf-deficient mice show a lack of melanocytes and small eyes caused by abnormal RIPE development. An interesting feature of Mitf is the existence of multiple isoforms with different amino termini and their functions in the development of these melanin-producing pigment cells. In this study, we isolated two Mitf homologues (XlMitfalpha and XlMitfbeta) and their isoforms from Xenopus laevis. Alignment analysis of the amino acid sequences of the N-termini suggests that these isoforms are homologues of mouse Mitf-M (expressed specifically in the melanocyte lineage) and Mitf-A (strongly expressed in the RPE, although this expression is ubiquitous). In Xenopus, XlMitfalpha is strongly expressed in the melanophore lineage (especially in premigratory melanoblasts) and the presumptive RPE and the epiphysis, in which melanin-producing cells differentiate in some vertebrates. Conservation of the Mitf isoforms expected to possess specific functions in the development of melanin-producing cells and of the expressions in such cell types in Xenopus suggest that XlMitf plays a central role in the development of melanin-producing cell lineages, and that, as in mice and humans, most of the signaling molecules or transcription factors implicated genetically in the development of melanin-producing cell lineages affect either Mitf expression or its function (Goding [2000] Genes Dev. 14:1712-1728). (C) Wiley-Liss, Inc.
  • Ichiro Yajima, Kosuke Endo, Shigeru Sato, Reiko Toyoda, Hiroshi Wada, Shigeki Shibahara, Takaharu Numakunai, Kazuho Ikeo, Takashi Gojobori, Colin R Goding, Hiroaki Yamamoto
    Mechanisms of development 120 (12) 1489 - 504 0925-4773 2003/12 [Refereed][Not invited]
    The microphthalmia-associated transcription factor (Mitf) is a basic-helix-loop-helix-leucine zipper (bHLH-ZIP) transcription factor essential for the development and function of all melanin-producing pigment cells in vertebrates. To elucidate the evolutionary history of Mitf and the antiquity of its association with pigment cells, we have isolated and characterized HrMitf, a sole member of the Mitf-TFE bHLH-ZIP subfamily in the ascidian Halocynthia roretzi. Maternal HrMitf mRNA is detected in the fertilized egg and in the animal hemisphere from 4-cell stage through the gastrula stage. From the neurula through the early tailbud stage, HrMitf is preferentially expressed in the pigment-lineage cells that express the lineage-specific melanogenesis genes tyrosinase (HrTyr) and Tyrp. Overexpression of HrMitf induced ectopic expression of HrTyr enzyme activity in mesenchymal cells where the same enzyme activity was induced by overexpression of HrPax3/7, suggesting that a part(s) of the Pax3-Mitf-tyrosinase gene regulatory cascade seen in vertebrate melanocytes is operative during ascidian embryogenesis. We also show HrMitf and mouse Mitf-A, a Mitf isoform abundantly expressed in pigmented epithelial cells, share similar functional characteristics. These results suggest antiquity of the association of the Mitf-TFE subfamily with pigment cells and may support the idea that acquisition of multiple promoters (isoforms) by an ancestral Mitf gene has allowed the evolution of multiple pigment cell types.
  • M Kumasaka, S Sato, Yajima, I, H Yamamoto
    PIGMENT CELL RESEARCH 16 (5) 455 - 462 0893-5785 2003/10 [Refereed][Not invited]
    The tyrosinase family of genes in vertebrates consists of three related members encoding melanogenic enzymes, tyrosinase (Tyr), tyrosinase-related protein-1 (TRP-1, Tyrp1) and tyrosinase-related protein-2 (Dct, TRP-2, Tyrp2). These proteins catalyze melanin production in pigment cells and play important roles in determining vertebrate coloration. This is the first report examining melanogenic gene expression in pigment cells during embryonic development of amphibians. Xenopus provides a useful experimental system for analyzing molecular mechanisms of pigment cells. However, in this animal little information is available not only about the developmental expression but also about the isolation of pigmentation genes. In this study, we isolated homologues of Tyr, Tyrp1 and Dct in Xenopus laevis (XlTyr, XlTyrp1, and XlDct). We studied their expression during development using in situ hybridization and found that all of them are expressed in neural crest-derived melanophores, most of which migrate through the medial pathway, and in the developing diencephalon-derived retinal pigment epithelium (RPE). Further, XlDct was expressed earlier than XlTyr and XlTyrp1, which suggests that XlDct is the most suitable marker gene for melanin-producing cells among them. XlDct expression was detected in migratory melanoblasts and in the unpigmented RPE. In addition, the expression of XlDct was detected in the pineal organ. The sum of these studies suggests that expression of the tyrosinase family of genes is conserved in pigment cells of amphibians and that using XlDct as a marker gene for pigment cells will allow further study of the developmental mechanisms of pigment cell differentiation using Xenopus.
  • S Sato, M Nakamura, DH Cho, SJ Tapscott, H Ozaki, K Kawakami
    HUMAN MOLECULAR GENETICS 11 (9) 1045 - 1058 0964-6906 2002/05 [Refereed][Not invited]
    Myotonic dystrophy 1 (DM1) is the most common inherited neuromuscular disease in adults. The disorder, characterized by myotonia, muscle wasting and weakness, cataract, insulin resistance, and mental Impairment, Is caused by the expansion of an unstable CTG repeat located in the 3' untranslated region of DMPK. The repeat expansion suppresses the expression of the homeobox gene SIX5. We describe here an experimental system to identify downstream transcriptional targets of mouse Six5 in order to elucidate the role of SIX5 in the pathogenesis of DM1 and development. By overexpressing a constitutively active Six5 (VP16-Six5wt) using adenovirus-mediated gene transfer in P19 cells and subsequent expression profiling using cDNA arrays, 21 genes, whose expression level increased by the treatment, were identified as potential target genes. Genes expressed in the somites, skeletal muscles, brain and meninges comprised the majority, suggesting the role of Six5 in the development and function of mesodermal tissues and brain. We provide evidence that lgfbp5 encoding a component of IGF signaling is a direct Six5-target. Moreover, the overall expression level of lgfbp5 was decreased in Six5 deficient mouse fibroblasts, and the response of human IGFBP5 to MyoD-induced muscle conversion was altered in cells of DM1 patients. Our results not only identify Six5 as an activator that directs lgfbp5 expression but also suggest that reduced SIX5 expression in DM1 might contribute to specific aspects of the DM1 phenotype.
  • S Sato, H Yamamoto
    PIGMENT CELL RESEARCH 14 (6) 428 - 436 0893-5785 2001/12 [Refereed][Not invited]
    In vertebrates, melanins produced in specialized pigment cells are required for visual acuity, camouflage, sexual display and protection from ultra violet (UV) radiation. There are three pigment cell types that are classified based on their distinct embryonic origins. Retinal pigment epithelium (RPE) cells originate from the outer layer of the optic cup. Pigment cells of the pineal organ are formed from the developing diencephalon. Melanocytes are derived from the neural crest unique to vertebrate embryos. Some of these pigment cells also play roles that are independent of the activity of tyrosinase, the key melanogenesis enzyme, or melanin: production of substrate(s) for catecholamine synthesis, maintenance of endolymph composition in the cochlea, maintenance of photoreceptor cells in the retina and retinoid metabolism essential for the visual cycle. To deduce the evolutionary origins of vertebrate pigment cells and a possible archetypal genetic circuitry, which may have been modified and utilized to generate multiple pigment cell types, comparison of developmental mechanisms of pigment cells between vertebrates and closely related invertebrate ascidians are proposed to provide useful information. The tadpole-type larva of ascidians possesses two melanin-containing pigment cells, termed the otolith and ocellus pigment cells, in the brain that are believed to be required for photo- and geotactic responses during swimming. In this review, current knowledge on the development of the two ascidian pigment cells is summarized, i.e. complete cell lineage, structure and expression of genes encoding two melanogenesis enzymes, and molecular developmental mechanisms involving BMP-CHORDIN antagonism, and possible evolutionary relationships between ascidian and vertebrate pigment cells are discussed.
  • S Sato, M Tanaka, H Miura, K Ikeo, T Gojobori, T Takeuchi, H Yamamoto
    JOURNAL OF INVESTIGATIVE DERMATOLOGY SYMPOSIUM PROCEEDINGS 6 (1) 10 - 18 1087-0024 2001/11 [Refereed][Not invited]
    Tyrosinase is the key enzyme for synthesizing melanin pigments, which primarily determine mammalian skin coloration. Considering the important roles of pigments in the evolution and the adaptation of vertebrates, phylogenetic changes in the coding and flanking regulatory sequences of the tyrosinase gene are particularly intriguing. We have now cloned cDNA encoding tyrosinase from Japanese quail and snapping turtle. These nonmammalian cDNA are highly homologous to those of the mouse and human tyrosinases, whereas the 5' flanking sequences are far less conserved except for a few short sequence motifs. Nevertheless, we demonstrate that the 5' flanking sequences from the quail or turtle tyrosinase genes are capable of directing the expression of a fused mouse tyrosinase cDNA when introduced into cultured mouse albino melanocytes. This experimental method, which reveals the functional conservation of regulatory sequences in one cell type (the melanocyte), may be utilized to evaluate phylogenetic differences in mechanisms controlling specific gene expression in many other types of cells. We also provide evidence that the 5' flanking sequences from these nonmammalian genes are functional in vivo by producing transgenic mice. Phylogenetic changes of vertebrate tyrosinase promoters and the possible involvement of conserved sequence motifs in melanocyte-specific expression of tyrosinase are discussed.
  • R Toyoda, S Sato, K Ikeo, T Gojobori, T Numakunai, CR Goding, H Yamamoto
    GENE 259 (1-2) 159 - 170 0378-1119 2000/12 [Refereed][Not invited]
    Tyrosinase is the key enzyme required for the synthesis of melanin pigments. Sequence comparison and functional analysis of the 5' upstream legions of vertebrate tyrosinase genes have revealed the importance of conserved E-box motifs in regulating their specific expression in pigment cells, optic cup-derived retinal pigment epithelium (RPE) and neural crest-derived melanocytes. In ascidians (more basal protochordates), two pigment cells that resemble vertebrate RPE cells are formed and specifically express the orthologous tyrosinase gene (HrTyr) in the cerebral vesicle located at the anterior end of the neural tube. To define regulatory sequences required for pigment cell-lineage-specific expression of HrTyr during embryogenesis, a series of mutations of the 5' upstream legion of HrTyr were fused to the lacZ reporter gene and were microinjected into fertilized eggs. We found that the -152 bp upstream of the translational start site is essential for expression in pigment cell precursors of tailbud-stage embryos. Further, additional positive and unique restriction elements were identified in the region up to -1.8 kb. Surprisingly, in the - 152 bp minimal promoter or in other legions with regulatory activities, there are no E-box motifs or sequences correlating with other conserved elements regulating vertebrate tyrosinase promoters. The possibility that Pax proteins regulate HrTyr expression is also discussed. (C) 2000 Elsevier Science B.V. All rights reserved.
  • K Kawakami, S Sato, H Ozaki, K Ikeda
    BIOESSAYS 22 (7) 616 - 626 0265-9247 2000/07 [Refereed][Not invited]
    The members of the Six gene family were identified as homologues of Drosophila sine oculis which is essential for compound-eye formation. The Six proteins are characterized by the Six domain and the Six-type homeodomain, both of which are essential for specific DNA binding and for cooperative interactions with Eya proteins. Mammals possess six Six genes which can be subdivided into three subclasses, and mutations of Six genes have been identified in human genetic disorders. Characterization of Six genes from various animal phyla revealed the antiquity of this gene family and roles of its members in several different developmental contexts. Some members retain conserved roles as components of the Pax-Six-Eya-Dach regulatory network, which may have been established in the common ancestor of all bilaterians as a toolbox controlling cell proliferation and cell movement during embryogenesis, Gene duplications and cia-regulatory changes may have provided a basis for diverse functions of Six genes in different animal lineages. (C) 2000 John Wiley & Sons, Inc.
  • Gonzalez, I, N Ohsawa, RH Singer, M Devillers, T Ashizawa, A Balasubramanyam, TA Cooper, M Khajavi, AS Lia-Baldini, G Miller, AV Philips, LT Timchenko, J Waring, H Yamagata, JP Barbet, TR Klesert, SJ Tapscott, AD Roses, M Wagner, M Baiget, L Martorell, GB Browne, B Eymard, G Gourdon, C Junien, H Seznec, N Carey, M Gosling, P Maire, M Gennarelli, S Sato, T Ansved, U Kvist, M Eriksson, D Furling, EJ Chen, DE Housman, B Luciano, M Siciliano, N Spring, M Shimizu, E Eddy, GE Morris, R Krahe, H Furuya, J Adelman, D Pribnow, D Furutama, J Mathieu, D Hilton-Jones, M Kinoshita, C Abbruzzese, RR Sinden, RD Wells, CE Pearson, T Kobayashi, A Johansson, S Salvatori, B Perryman, MS Swanson, FK Gould, SE Harris, K Johnson, AM Mitchell, DG Monckton, CL Winchester, G Antonini, JW Day, C Liquori, LPW Ranum, J Westerlaken, B Wieringa, JD Griffith, S Michalowski, H Moore, M Hamshere, Z Korade, CA Thornton, H Jaeger, F Lehmann, Moorman, JR, JP Mounsey, MS Mahadevan
    NEUROLOGY 54 (6) 1218 - 1221 0028-3878 2000/03 [Refereed][Not invited]
  • H Ohto, S Kamada, K Tago, S Tominaga, H Ozaki, S Sato, K Kawakami
    MOLECULAR AND CELLULAR BIOLOGY 19 (10) 6815 - 6824 0270-7306 1999/10 [Refereed][Not invited]
    Drosophila sine oculis and eyes absent genes synergize in compound-eye formation, The murine homologues of these genes, Six and Eya, respectively, show overlapping expression patterns during development. We hypothesized that Six and Eya proteins cooperate to regulate their target genes. Cotransfection assays were performed with various combinations of Six and Eya to assess their effects on a potential natural target, myogenin promoter, and on a synthetic promoter, the thymidine kinase gene promoter fused to multimerized Six4 binding sites, A clear synergistic activation of these promoters was observed in certain combinations of Six and Eya, To investigate the molecular basis for the cooperation, we first examined the intracellular distribution of Six and Eya proteins in transfected COS7 cells, Coexpression of Six2, Six4, or Six5 induced nuclear translocation of Eya1, Eya2, and Eya3, which were otherwise distributed in the cytoplasm, In contrast, coexpression of Six3 did not result in nuclear localization of any Eya proteins. Six and Eya proteins were coimmunoprecipitated from nuclear extracts prepared from cotransfected COS7 cells and from rat liver. Six domain and homeodomain, two evolutionarily conserved domains among various Six proteins, were necessary and sufficient for the nuclear translocation of Eya, In contrast, the Eya domain, a conserved domain among Eya proteins, was not sufficient for the translocation, A specific interaction between the Six domain and homeodomain of Six4 and Eya2 was observed by yeast two-hybrid analysis. Our results suggest that transcription regulation of certain target genes by Six proteins requires cooperative interaction with Eya proteins: complex formation through direct interaction and nuclear translocation of Eya proteins. This implies that the synergistic action of Six and Eya is conserved in the mouse and is mediated through cooperative activation of their target genes.
  • S Sato, R Toyoda, Y Katsuyama, H Saiga, T Numakunai, K Ikeo, T Gojobori, Yajima, I, H Yamamoto
    DEVELOPMENTAL DYNAMICS 215 (3) 225 - 237 1058-8388 1999/07 [Refereed][Not invited]
    The tyrosinase family in vertebrates consists of three related melanogenic enzymes: tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2, These proteins control melanin production in pigment cells and play a crucial role in determining vertebrate coloration. We have isolated a gene from the ascidian Halocynthia roretzi which encodes a tyrosinase-related protein (HrTRP) with 45-49% identity with vertebrate TRP-1 and TRP-2, The expression of the HrTRP gene in pigment lineage a8.25 cells starts at the early-mid gastrula stage, which coincides with the stage when these cells are determined as pigment precursor cells; therefore, it provides the earliest pigment lineage-specific marker, which enables us to trace the complete cell lineage leading to two pigment cells in the larval brain. In addition, the expression pattern of the HrTRP gene appears to share similar characteristics with the mouse TRP-2 gene although structurally the HrTRP gene is more closely related to mammalian TRP-I genes. Based on these observations and on results from molecular phylogenetic and hybridization analyses, we suggest that triplication of the tyrosinase family occurred during the early radiation of chordates. Initially, duplication of an ancestral tyrosinase gene produced a single TRP gene before the urochordate and cephalochordate-vertebrate divergence, and a subsequent duplication of the ancestral TRP gene in the vertebrate lineage gave rise to two TRP genes before the emergence of teleost fishes. Evolution of the melanin synthetic pathway and possible phylogenetic relationships among chordate pigment cells that accommodate the metabolic process are discussed, (C) 1999 Wiley-Liss, Inc.
  • S Amae, N Fuse, K Yasumoto, S Sato, Yajima, I, H Yamamoto, T Udono, YK Durlu, M Tamai, K Takahashi, S Shibahara
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 247 (3) 710 - 715 0006-291X 1998/06 [Refereed][Not invited]
    Mutations at the mouse locus encoding microphthalmia-associated transcription factor (Mitf) affect the development of many cell types, including retinal pigment epithelium (RPE), melanocytes, mast cells, and osteoclasts. Here we have identified a novel Mitf isoform, Mitf-a, and its human homologue MITF-A by cDNA cloning. MITF-A consists of 520 amino acid residues and differs in the amino-terminus from authentic melanocyte-type MITF (MITF-M). MITF-A mRNA is widely expressed and represents a predominant MITF isoform in cultured RPE cells, whereas MITF-M mRNA is exclusively expressed in melanocytes and melanoma cells. In situ hybridization analysis suggested that Mitf-a mRNA is enriched in the prospective RPE of mouse embryo. Moreover, transient cotransfection assays suggested that MITF-A activated transcription of the tyrosinase and tyrosinase-related protein 1 genes. MITF-A/Mitf-a therefore may play an important role in melanogenesis in RPE. (C) 1998 Academic Press.
  • HJ Yuasa, S Sato, H Yamamoto, T Takagi
    JOURNAL OF BIOCHEMISTRY 122 (2) 374 - 380 0021-924X 1997/08 [Refereed][Not invited]
    The solitary ascidian Halocynthia roretzi possesses three types of muscle: the larval tail striated muscle, the adult heart striated muscle, and the adult body wall smooth muscle, The troponin complex is observed in ail types of muscle, and the isoform sequences and expression patterns of two of the three troponin components, troponins C and T, have been reported, In this study, we have determined cDNA sequences of the three TnI isoforms from H. roretzi. One of the three isoforms (adult TnI), expressed in adult body wall smooth muscle and heart muscle, was composed of 173 amino acids, being similar to vertebrate fast and slow skeletal TnIs in length, The other two isoforms (larval TnI alpha and TnI beta) were isolated from a cDNA library of larvae. Both larval TnIs were composed of 142 amino acids, with truncation amounting to ca, 30 amino acid residues at the C-termini, These larval TnIs are the smallest known TnIs. The position of the last intron of these TnIs was also determined. When compared with vertebrate TnI genes, the last intron of the ascidian adult TnI gene is located at 6 nucleotides downstream, and the introns of the two larval TnIs are positioned at 9 nucleotides upstream, These results suggest that H. roretzi TnI is encoded by at least three genes.
  • H Wada, PWH Holland, S Sato, H Yamamoto, N Satoh
    DEVELOPMENTAL BIOLOGY 187 (2) 240 - 252 0012-1606 1997/07 [Refereed][Not invited]
    The origin and elaboration of the central nervous system played an important role in chordate and vertebrate history. All chordates possess a dorsal tubular central nervous system, but elaboration of dorsoventral and segmental pattern is far more pronounced in cephalochordates and vertebrates than in the more basal urochordates. Analysis of the urochordates, therefore, should allow deduction of the neural organization and neuronal patterning mechanisms that predated overt dorsoventral and segmental complexity. Here we report functional studies of the ascidian Pax gene (HrPax-37). The spatiotemporal expression pattern of HrPax-37 has suggested involvement in two distinct developmental processes: specification of dorsal cell fates of ectoderm during neurulation, and regional differentiation of the neural tube in later stages. Here we show that HrPax-37 is descendent from the precursor of the Pax-3 and Pax-7 genes implicated in specification of dorsal fate in the vertebrate neural tube. We also demonstrate that injection of HrPax-37 RNA into fertilized eggs causes ectopic expression of the dorsal neural marker tyrosinase gene in neurulae, confirming a regulatory role in dorsal patterning of the neural tube comparable to its vertebrate homologues. These results suggest that dorsal specification in the neural tube by Pax-3/7 subfamily genes was established in the ancestors of extant chordates during emergence of the dorsal tubular nervous system. (C) 1997 Academic Press.
  • S Sato, K Roberts, G Gambino, A Cook, T Kouzarides, CR Goding
    ONCOGENE 14 (25) 3083 - 3092 0950-9232 1997/06 [Refereed][Not invited]
    The Microphthalmia basic-Helix-loop-Helix-Leucine Zipper (bHLH-LZ) transcription factor (Mi) plays a crucial role in the genesis of melanocytes; mice deficient for a functional (Microphthalmia) gene product lack all pigment cells, We show here that the Mi activation domain resides N-terminal to the DNA-binding domain and that as little as 18 amino acids are sufficient to mediate transcription activation, The minimal activation region of Mi is highly conserved in the related transcription factor TFE3 and is predicted to adopt an amphipathic alphahelical conformation, This region of Mi is also highly conserved with a region of E1A known to be essential for binding the CBP/p300 transcription cofactor, Consistent with these observations, the Mi activation domain can interact in vitro with CBP specifically through a region of CBP required for complex formation with E1A, P/CAF and c-Fos, and anti p300 antibodies can co-immunoprecipitate Mi from both melanocyte and melanoma cell lines, In addition, co-transfection of a vector expressing CBP2 (aas 1621-1891) fused to the VP16 activation domain potentiated the ability of Mi to activate transcription, confirming the significance of the CBP-Mi interaction observed in vitro. These data suggest that transcription activation by Mi is achieved at least in part by recruitment of CBP, The parallels between transcription regulation by Microphthalmia in melanocytes and MyoD in muscle cells are discussed.
  • HJ Yuasa, S Sato, H Yamamoto, T Takagi
    JOURNAL OF BIOCHEMISTRY 121 (4) 671 - 676 0021-924X 1997/04 [Refereed][Not invited]
    Two distinct cDNAs encoding troponin C (TnC) isoforms were isolated from the ascidian, Halocynthia roretzi, One is expressed in adult body wall smooth muscle and heart muscle, and the other in larval striated muscle, The H. rorezti gene is composed of 7 exons separated by B introns, and Southern blot analysis showed that TnC is a single copy gene product. The two isoforms of TnC were derived through the alternative splicing of the third exon.
  • S Sato, H Masuya, T Numakunai, N Satoh, K Ikeo, T Gojobori, K Tamura, H Ide, T Takeuchi, H Yamamoto
    DEVELOPMENTAL DYNAMICS 208 (3) 363 - 374 1058-8388 1997/03 [Refereed][Not invited]
    Tadpole larvae of ascidians have two sensory pigment cells in the brain, One is the otolith cell that functions as a gravity receptor, the other pigment cell is part of a primitive photosensory structure termed the ocellus. These sensory cells, like vertebrate pigment cells, contain membrane-bounded melanin granules and are considered to reflect a crucial position in the evolutionary process of this cell type, To investigate the molecular changes accompanying the evolution of pigment cells, we have isolated from Halocynthia roretzi a gene encoding tyrosinase, a key enzyme in melanin biosynthesis, The cDNA has an open reading frame (ORF) of 596 amino acids, which is 36-39% identical in amino acid sequence to vertebrate tyrosinases, In addition, the sequence analysis of both cDNA and genomic clones reveals an unusual organization of the tyrosinase gene, an extraordinary 3' untranslated region of the transcripts with significant homology to the coding sequence, and a single short intron in the sequence encoding a cytoplasmic domain, Expression of the gene is detected first in two pigment precursor cells positioned in the neural plate of early neurulae, and later in two melanin-containing pigment cells within the brain of late tailbud embryos, Its expression pattern correlates well with the appearance of tyrosinase enzyme activity in the developing brain, These results provide the first description of pigment cell differentiation at the molecular level in the ascidian embryo, and also will contribute to a better understanding of the evolution of chordate pigment cells. (C) 1997 Wiley-Liss, Inc.
    PIGMENT CELL RESEARCH 7 (5) 279 - 284 0893-5785 1994/10 [Refereed][Not invited]
    Several nuclear factors that interact with sequences in the 5' flanking region of the mouse tyrosinase gene were identified using band shift and methylation interference assays. One of these factors bind to an AT-rich sequence, TATCAATTAG, located at -183 base pairs upstream of the transcription start site. To isolate cDNA clone encoding this DNA binding protein, we have screened a lambda gtll cDNA expression library prepared from mouse melanocyte cell line with a labeled oligonucleotide probe containing its binding site. Complementary DNA clones encoding mouse high mobility group protein HMG-I and its isoform HMG-Y were obtained. HMG-I(Y) is a low molecular size, basic nuclear protein that binds specifically to AT-rich region of double-stranded DNA in vitro. In Northern blot analysis the level of HMG-I(Y) mRNA expression did not correlate with that of tyrosinase or TRP-1. Although the amount of HMG-I(Y) transcripts has no apparent influence on the mouse tyrosinase gene expression, it is possible that HMG-I(Y) binds to the 5' flanking sequence of the tyrosinase gene as an auxiliary factor, and facilitates the binding and activity of other transcription factors.
    PIGMENT CELL RESEARCH 5 (5) 284 - 294 0893-5785 1992/11 [Refereed][Not invited]
    Highly homologous DNA elements were found to be shared by the upstream regions of the mouse tyrosinase and tyrosinase related protein (TRP-1) genes. Several nuclear proteins were shown to bind to both of these upstream regions. Shared homologous DNA elements were also found in the 5' flanking sequences of Japanese quail and snapping turtle tyrosinase genes. Shared homologous nucleotide sequences were found to be scattered like an archipelago in the 5' upstream regions of mouse and human tyrosinase genes. Comparisons between Japanese quail and snapping turtle tyrosinase genes gave similar results. On the contrary, mammalian (mouse and human) and nonmammalian (quail and snapping turtle) tyrosinase genes did not show significant homology in their 5' upstream regions. In contrast, coding sequences in the first exons of vertebrate tyrosinase genes and their deduced amino acid sequences were found to be highly conserved except for their putative leader sequence-coding regions.

Conference Activities & Talks

  • Regulation of Six1 expression during hair cell development in the inner ear
    Sato S, Kawakami K
    日本発生生物学会第53回大会(2020.5.19-22, 熊本)  2020/05
  • The development of a novel tool to analyze cranial placode development
    Sato S, Fruta Y, Kawakami K
    日本発生生物学会第50回大会(2017.5.10-13, 東京)  2017/05
  • Dynamic transcriptional regulation of the deafness gene Six1 during otic development  [Not invited]
    Sato S, Kawakami K
    The 13th Nikko International Symposium. Innovative Technologies for Development – and Aging – related Research(2016.10.28, 栃木)  2016/10
  • 脊椎動物の感覚神経系におけるSix1発現制御メカニズム
    佐藤 滋, 矢嶋 浩, 塩井 剛, 清成 寛, 古田 泰秀, 池田 啓子, 川上 潔
    日本動物学会第86回大会(2015.9.17-19, 新潟)  2015/09
  • Activation of Six1 expression in vertebrate sensory neurons
    Sato S, Yajima H, Shioi G, Kiyonari H, Furuta Y, Ikeda K, Kawakami K
    日本発生生物学会第48回大会(2015.6.2-5, つくば)  2015/06
  • Six1遺伝子の感覚神経系における役割とその発現制御
    佐藤 滋, 矢嶋 浩, 川上 潔
    日本遺伝学会第86回大会(2014.9.17-19, 長浜)  2014/09
  • Six1ホメオボックス遺伝子と脊椎動物の発生と進化  [Invited]
    佐藤 滋, 川上 潔
    第4回Tokyo Vertebrate morphology Meeting(2014.7.12, 東京)  2014/07
  • Six1 homeobox genes in the evolution of the sensory nervous system  [Invited]
    Sato S, Yajima H, Kawakami K
    学融合推進センター・共同研究プロジェクト研究会「脳の進化―大脳新皮質の起源を尋ねて―」(2012.11.12-13, 葉山)  2012/11
  • Sato S, Ikeda K, Shioi G, Nakao K, Aizawa S, Yajima H, Kawakami K. Conservation and diversity of Six1 gene enhancers in chordates.
    第45回日本発生生物学会・第64回日本細胞生物学会合同大会(2012.5.28-31, 神戸)  2012/05
  • Six1 enhancers as a tool to understand sensory organogenesis
    Sato S, Ikeda K, Shioi G, Nakao K, Aizawa S, Yajima H, Kawakami K
    EMBO Workshop: Frontiers in sensory development(2011.5.3-6, Barcelona)  2011/05
  • 脊椎動物の感覚器形成の初期過程の理解を目指して
    佐藤 滋, 池田 啓子, 塩井 剛, 中尾 和貴, 相沢 慎一, 矢嶋 浩, 川上 潔
    日本動物学会第81回大会(2010.9.23-25, 東京)  2010/09
  • 感覚器官の起源と多様化  [Invited]
    佐藤 滋, 川上 潔
    日本遺伝学会第82回大会(2010.9.20-22, 札幌)  2010/09
  • Six1 enhancers as a tool to understand vertebrate sensory organogenesis
    Sato S, Ikeda K, Shioi G, Nakao K, Aizawa S, Yajima H, Kawakami K
    日本発生生物学会第43回大会(2010.6.20-23, 京都)  2010/06
  • Identification of a common sensory precursor domain, the pre-placodal region (PPR), in mammalian embryos  [Not invited]
    Sato S, Ikeda K, Yajima H, Kawakami K
    The 6th Nikko International Symposium. Frontiers of Molecular Medicine(2009.11.7, 栃木)  2009/11
  • Cis-regulatory mechanisms controlling Six1 expression in the preplacodal region and sensory placodes
    Sato S, Ikeda K, Hayashibara Y, Nakao K, Aizawa S, Ochi H, Ogino H, Kawakami K
    日本発生生物学会第42回大会(2009.5.28-31, 新潟)  2009/05
  • Characterization of Six1 enhancers: Implication for the development and evolution of PPR and sensory placodes  [Not invited]
    Sato S, Ikeda K, Hayashibara Y, Nakao K, Aizawa S, Ochi H, Ogino H, Kawakami K
    The 18th CDB Meeting. Common themes and new concepts in sensory formation(2009-4.13-15, 神戸)  2009/04
  • Evolution of preplacodal region and sensory placodes  [Not invited]
    Sato S, Ikeda K, Hayashibara Y, Nakao K, Aizawa S, Kawakami K
    The 16th CDB Meeting. Cis-sequence regulation and its evlution(2008.9.29-10.1, 神戸)  2008/09
  • Evolution of Six1 enhancers in vertebrates.
    Sato S, Ikeda K, Nakayama R, Bunno T, Hayashibara Y, Aizawa S, Kawakami K
    日本発生生物学会第41回大会(2008.5.28-30)  2008/05
  • マウスとニワトリ胚を用いたプラコードエンハンサーのin vivo解析
    佐藤 滋, 中山 里果, 池田 啓子, 林原 康典, 中尾 和貴, 相沢 慎一, 川上 潔
    日本発生生物学会第40回大会(2007.5.28-30, 福岡)  2007/05
  • Molecular dissection of the placode specific gene expression  [Not invited]
    Sato S, Ishihara T, Kawakami K
    The First and Founding meeting of the European Society for Evolutionary Developmental Biology(2006.8.16-19, Prague)  2006/08
  • Molecular dissection of Six1 placode enhancers
    佐藤 滋, 石原 忠, 川上 潔
    日本発生生物学会第39回大会(2006.5.31-6.3, 広島)  2006/05
  • Evolutionarily conserved enhancers direct the expression of Six1 in cranial placodes
    Sato S, Ishihara T, Kawakami K
    The 15th International Society of Developmental Biologists Congress(2005.9.3-9, Sydney)  2005/09
  • Six1のプラコード特異的発現のメカニズム
    佐藤 滋, 川上 潔
    日本発生生物学会第38回大会(2005.6.1-4, 仙台)  2005/06
  • Six5-target genes and DM1 symptoms  [Not invited]
    Sato S, Takiguchi M, Nakamura M, Reddy S, Ibaraki N, Kawakami K
    The 4th International Myotonic Dystrophy Conference(2003.4.10-12, Glasgow)  2003/04
  • Larval photoreceptor of the ascidian Halocynthia roretzi that is independent of Pax6 or Six homeobox genes  [Not invited]
    Sato S, Nakamura M, Kawakami K
    Santa Cruz Conference on Developmental Biology  2002/08  Santa Cruz
  • Six-Eya-Dach遺伝子と発生プログラムの進化
    佐藤 滋, 中村 美和, Patrick Lemaire, 川上 潔
    日本発生生物学会第35回大会(2002.5.21-23, 横浜)  2002/05
  • Transcriptional targets of SIX5  [Not invited]
    Sato S, Nakamura M, Bergstrom DA, Tapscott SJ, Tomarev S, Ibaraki N, Kawakami K
    The 3rd International Myotonic Dystrophy Conference(2001.10.9-11, 京都)  2001/10
  • Transcriptional targets of Six homeodomain proteins
    Sato S, Bergstrom DA, Tapscott SJ, Kawakami K
    The 14th International Congress of Developmental Biology(2001.7.8-12, 京都)  2001/07
  • Functional analyses of DMAHP/SIX5.  [Not invited]
    Sato S, Kawakami K
    COE Symposium 2000 on Muscular Dystrophy-molecular and cellular mechanisms and gene therapy(2000.3.14-16, 東京)  2000/03
  • Molecular characterization of the black-eyed white (Mitf) gene: the loss of a single Mitf isoform results in pigmentary defect and hearing loss  [Not invited]
    Sato S, Yajima I, Yoshida Y, Yasumoto K, Shibahara S, Goding CR, Yamamoto H
    The XVIIth International Pigment Cell Conference(1999.10.30-11.3, 名古屋)  1999/11
  • Synergy of Six and Eya in gene transcription  [Invited]
    Sato S, Ohto H, Kamada S, Ozaki H, Kawakami K
    The 2nd International Myotonic Dystrophy Consortium Conference(1999.4.21-23, Durham, NC)  1999/04
  • 原索動物マボヤの色素細胞における脊椎動物チロシナーゼ遺伝子のシス・エレメントの活性
    佐藤 滋, 豊田 礼子, 池尾 一穂, 五條堀 孝, 山本 博章
    日本遺伝学会第70回大会(1998.9.23-25, 札幌)  1998/09
  • チロシナーゼファミリー遺伝子の系統解析
    佐藤 滋, 豊田 礼子, 山本 博章
    日本遺伝学会第69回大会(1997.11.1-3, 横浜)  1997/11
  • マウスMicrophthalmiaタンパク質の機能解析
    佐藤 滋, Colin R. Goding, 山本 博章
    日本色素細胞学会第11回大会(1996.12.6-7, 川崎)  1996/12
  • マウスMITFの機能解析
    佐藤 滋, Colin R. Goding, 矢嶋 伊知朗, 山本 博章
    日本遺伝学会第68回大会(1996.10.3-5, 名古屋)  1996/10
  • マボヤの色素細胞で発現する遺伝子と色素細胞の発生
    佐藤 滋, 山本 博章
    日本発生生物学会大28回大会(1995.5.29-31, 名古屋)  1995/05
  • マボヤチロシナーゼ遺伝子群の発現
    佐藤 滋, 田村 宏治, 井出 宏之, 竹内 拓司, 山本 博章
    日本動物学会第65回大会(1994.10.5-8, 名古屋)  1994/10
  • マボヤの色素細胞で発現する遺伝子群
    佐藤 滋, 竹内 拓司, 山本 博章
    日本発生生物学会大27回大会(1994.5.25-27, 仙台)  1994/05
  • マウス色素細胞におけるDNA結合タンパク質HMG I(Y)の機能解析
    佐藤 滋, 三浦 裕仁, 山本 博章, 竹内 拓司
    日本遺伝学会第65回大会(1993.9.17-19, 三島)  1993/09
  • Identification of nuclear factors that bind to the mouse tyrosinase gene regulatory region  [Not invited]
    Sato S, Miura H, Yamamoto H, Takeuchi T
    The XV International Pigment Cell Conference(1993.9.26-30, London)  1993/09
  • マウスチロシナーゼ遺伝子の5’上流域に結合するタンパク質の解析  [Not invited]
    佐藤 滋, 三浦 裕仁, 山本 博章, 竹内 拓司
    日本遺伝学会第64回大会(1992.10.22-24, 仙台)  1992/10


Research Grants & Projects

  • 聴覚と平衡覚を担う内耳感覚上皮の形成とその配置の分子機構の解明
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    Date (from‐to) : 2019/04 -2022/03 
    Author : 佐藤 滋
    胎生17.5日マウス胚から単離した蝸牛有毛細胞のATAC-seq解析により、Six1遺伝子のTAD(topologically associating domain)内に7ヶ所のオープンクロマチン領域を同定した。これら7ヶ所の配列はSix1の有毛細胞特異的エンハンサーの候補である。今年度は、最もピーク値が高いATAC1配列を欠損するマウスの作製を試みた。ATAC1はSix1エクソン周辺の非コード配列中で最も保存性の高い耳プラコード/嗅上皮/上鰓神経節/脳下垂体前葉/唾液腺エンハンサー(Six1-21エンハンサー)を含んでおり、その欠失はSix1の発現レベル低下を引き起こし、内耳有毛細胞もしくはより早期の耳胞のパターニングに影響を及ぼす可能性も考えられた。
    Six1エキソンの3'側に位置するATAC1配列を含む約1.5 kbを欠失させるために2種類のgRNAをデザインし、エレクトロポレーションにより受精卵に導入した。生まれたマウスの中の1個体でPCRと配列解析によりATAC1の欠失を確認することができた。このマウスをΔATAC1ファウンダーマウスとし、野生型マウスとの交配によるバッククロスを開始した(以上、理研BRC天野孝紀先生との共同研究)。ΔATAC1ヘテロ個体同士の交配により得られた仔マウスの遺伝子型を調べたところ、ホモ個体が複数含まれていた。以上より、ATAC1の欠失でSix1の発現レベルが全体として低下し、Six1欠損マウスのように致死になることはないということがわかった。
  • Cellular mechanism of abdominal body wall closure
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2019/04 -2020/03 
    Author : 川上 潔, 高橋 将文, 佐藤 滋
    本研究計画は腹壁形成に異常が生じるSix4/Six5 二重欠損マウスと野生型マウスを用いて、腹壁形成の細胞機序を明らかにすることを目的とする。本年度は下記の実験を行い、研究計画を終了した。 1. 初期腹壁における体腔上皮細胞及び間葉細胞の標識とタイムラプス観察 全胚培養マウスの体腔中に蛍光色素(CSFE)を注入し、体腔上皮細胞を標識した。培養1日後に標識した胚の初期腹壁の切片を作製し、蛍光顕微鏡観察したところ、標識された上皮細胞の一部が間葉に移動していた。体腔上皮細胞を標識する方法が確立できたので、今後、タイムラプス観察を行い、体腔上皮細胞の上皮間葉転換の様相、陥入した間葉細胞の移動速度や移動経路を、野生型とSix4/Six5 二重欠損マウス胚で比較解析する。 2. 腹壁における細胞系譜の分子遺伝学的手法による追跡 初期腹壁の体腔上皮細胞に早期から発現するWnt2b遺伝子下流にCreERT2遺伝子を発現するマウスを筑波大学と共同で構築した。本マウスをLacZ発現レポーターマウスと交配し、Tamoxifen投与2日後に胚のX-gal染色を行った。内在性のWnt2b遺伝子の発現部位にLacZの発現を認めた。これらのマウスとSix4/Six5 二重欠損マウスとを交配したうえ、腹壁細胞の細胞移動や形態を野生型マウス胚の細胞と比較観察中である。
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2016/04 -2019/03 
    Author : SATO shigeru
    The vertebrate inner ear responsible for hearing and balance is one of the most complex organs. This study aimed to understand the regulation and function of the key homeobox gene Six1. We carried out ATAC-seq analysis using hair cells isolated from E17.5 mouse embryos, and identified 7 candidate hair cell-enhancers located in the Six1-TAD. In addition, SIX1-binding sequences were enriched in top 1,105 hair cell-specific ATAC-seq peaks. This strongly suggest that SIX1 controls not only Atoh1 but also many hair cell genes and acts as the key transciption factor characterizing hair cells. We also established a new Six1-flox mouse strain and crossed them with mice expressing Cre in the otic placode, sensory neurons, hair cells and surrounding mesoderm. These mice should allow us a deeper understanding of the function of Six1 during the formation of the inner ear.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2013/04 -2016/03 
    Author : SATO Shigeru
    The aim of this study was to understand genetic and cellular characteristics of the sensory placodes and their precursor domain (PPR). 1) All materials required for the identification of Six1-target genes were prepared. 2) The PPR-specific enhancer of Xenopus Six1 was characterized. 2) Two new mouse lines expressing Cre under the control of two placode-specific Six1 enhancers were developed. 4) Cell ablation experiments were carried out using the two Cre-expressing mouse lines. The above results provided novel information on the regulation and function of Six1 and Six1-expressing cells, and should advance our understandings on the sensory organogenesis.
  • チスイコウモリの感覚世界の理解
    Date (from‐to) : 2011/04 -2012/03 
    Author : 佐藤 滋
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2010 -2012 
    Author : SATO Shigeru
    Sensory organs of vertebrate heads are formed as follows: ectoderm→pre-placodal region→various sensory placodes. Six1 is the key gene in the process. In this study, we sought to understand the cell-lineage, differentiation and roles of sensory placodes du
  • EMBO Workshops: Frontiers in Sensory Development
    Date (from‐to) : 2011/05 -2011/05 
    Author : 佐藤 滋
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2007 -2008 
    Author : SATO Shigeru
    Six1 ホメオボックス遺伝子の発現解析により多様な感覚器プラコードの共通の原基であるpreplacodal region(PPR)の存在をマウスではじめて示した。次にニワトリとマウス胚の前側PPR でSix1 の発現を活性化する保存されたエンハンサーを同定した。Six1 前側PPR エンハンサーの活性化因子と抑制因子の有力な候補を同定し、Six1 発現領域(=PPR)が規定される分子基盤の一端を明らかにした。また、2 種類のSix1 プラコードエンハンサーの制御下でCre リコンビナーゼを発現するマウスの樹立に成功した。
  • 内耳形成を司る遺伝子カスケードの解明
    Date (from‐to) : 2005/04 -2006/03 
    Author : 佐藤 滋
  • The 15th International Society of Developmental Biologists Congress
    Date (from‐to) : 2005/08 -2005/08 
    Author : 佐藤 滋
  • 感覚器形成におけるパターニング
    日本学術振興会:科学研究費助成事業 特定領域研究
    Date (from‐to) : 2004 -2005 
    Author : 川上 潔, 小西 慶幸, 佐藤 滋, 池田 啓子
    Six1/Six4二重欠損マウスではE10.5において三叉神経節内にアポトーシスが原因だと考えられる凝縮した核が多数検出されたが、E13.5ではこのような凝縮した核の増加は観察されなかった。抗一本鎖DNA抗体、抗活性化カスパーゼ抗体を用いた解析により、アポトーシスの増加がSix1/Six4二重欠損マウスで観察される三叉神経節の萎縮の要因の一つであることが示唆された。Six1/Six4二重欠損マウスの三叉神経節から得られた神経細胞を培養すると神経栄養因子の存在下でもアポトーシスを起こすことから、細胞内在的な要因の存在が示唆された。Six1/Six4欠損マウス三叉神経節では、生存因子であるBcl-xや神経栄養因子の受容体であるTrkCの発現低下が観察されたため、Six1/Six4によるこれらの因子の発現維持が三叉神経節の発生に関与することが示唆された。 Six1と隣接するSix4を含む180kbpのゲノム領域を種々の脊椎動物で比較した。ヒト-マウス間で保存され、かつ哺乳類以外の脊椎動物のいずれかでも保存された23の非エクソン配列を同定した。マウスゲノムよりPCRにて増幅した保存配列をptkEGFPベクターに挿入し、ニワトリ胚を用いてエンハンサー活性の検索を行った。その結果、プラコード原基(PPR)、種々のプラコードとプラコードに由来する感覚器と脳神経節においてEGFPの発現を活性化する6種類の独立したエンハンサーを同定した。これら6種類のエンハンサー活性を重ね合わせると、マウス及びニワトリ胚の種々のプラコードにおけるSix1とSix4本来の発現パターンがほぼ再現される。 嗅神経細胞の初期に発現するNeurogenin1、Lhx2、NeuroD等の発現の低下がSix1/Six4二重欠損マウスにおいて観察された。また、GAP43,Tuj1陽性の細胞は形成されるが嗅神経の成熟マーカーであるOMPの陽性細胞は全く見られなかった。加えて、嗅繊毛が観察されず嗅上皮における配向が消失していた。一方、支持細胞のマーカーであるサイトケラチン陽性の細胞は存在するが、支持細胞の嗅上皮での配向は消失していた。神経分化を抑制することが知られているHes1およびHes5の発現がホモマウスの嗅上皮では亢進していた。これらの観察から、Six1は嗅上皮の嗅神経細胞や支持細胞の発生・分化を司り、上皮構造の形成維持にもかかわることが明らかとなった。
  • 筋緊張性ジストロフィーの分子病態とSIX5標的遺伝子
    Date (from‐to) : 2003/04 -2004/03 
    Author : 佐藤 滋
  • 日本学術振興会:科学研究費助成事業 若手研究(B)
    Date (from‐to) : 2003 -2004 
    Author : 佐藤 滋
    目的:水晶体上皮及び性腺由来培養細胞におけるSIX5標的遺伝子、標的分子の検索を行うことで、SIX5の発現量低下がどのような標的遺伝子の発現異常を引き起こし、細胞や組織の性質を変え、DM1における白内障と性腺機能低下症を引き起こすのか、その分子基盤の解明を目指す。 結果:VP16の転写活性化ドメインを融合させた野生型SIX5、及び特異的DNA結合能を欠く変異型SIX5を水晶体上皮細胞、顆粒膜細胞で過剰発現させ、24時間後にRNAを抽出し、2種類のcDNAプローブを合成した。マイクロアレイを用いて野生型と変異型とで発現レベルが2倍以上異なる遺伝子を標的候補として同定した。水晶体上皮細胞で同定した227遺伝子には白内障との因果関係が示されている遺伝子(PITX3、TGFB2、KMO、GJA1)が含まれており、さらに水晶体透明度の維持に不可欠なイオンチャンネルやトランスポーターの遺伝子が複数含まれていた。顆粒膜細胞で同定した310遺伝子には性腺機能低下症との因果関係が示されている遺伝子((CYP19A1、ESR1、NRIP1、GATA4、BDNF)が含まれており、また性腺の形成や機能に関わる可能性の高い複数の遺伝子も含まれていた。10個以上の遺伝子についてRT-PCRによる検証実験を行い、アレイ解析で検出した発現レベルの変動パターンを確認した。こうした遺伝子の発現レベルを局所的に増減させ、白内障や性腺の機能を低下させるという機序が示唆された。 また、Six5タンパク質がCCUGリピート(DM1と類似の症状を発症するDM2で伸長する)にin vitroで結合することを示し、SIX5がRNA結合能を持つ転写因子であることを明らかにした。SIX5はDM2においても白内障と性腺機能低下症の発症過程に関与する可能性が示唆された。
  • The 4th International Myotonic Dystrophy Consortium Conference
    IDMC-4:Travel Fund
    Date (from‐to) : 2003/04 -2003/04 
    Author : 佐藤 滋
  • Sixホメオボックス遺伝子による器官形成プログラムの解明
    Date (from‐to) : 2002/04 -2003/03 
    Author : 佐藤 滋
  • Six-Eya-Dach遺伝子ネットワークによる器官形成
    日本学術振興会:科学研究費助成事業 特定領域研究
    Date (from‐to) : 2002 -2003 
    Author : 川上 潔, 佐藤 滋, 尾崎 秀徳, 池田 啓子
    ホメオボックス遺伝子Six、その転写コアクチベーターEya、及びEyaとの共同作用因子Dachは互いの相互作用と遺伝子発現のフィードバックループを介して骨格筋、感覚器、腎臓などの器官形成を司る。本研究では、Six遺伝子欠損マウスの解析とSixタンパク質の標的遺伝子の同定を通じて、器官形成にいたる分子メカニズムを明確にする。本年度はSix1遺伝子破壊マウスでの内耳の異常形成機序、six1,Six4およびSix5の標的遺伝子同定を中心に研究を進めた。 (1)six1遺伝子欠損ホモマウスは、内耳、鼻、胸腺、骨格筋および腎臓の形成不全がみられ、生直後に死亡する。耳胞での発生制御遺伝子群の発現を精査した。耳胞腹側の遺伝子発現が消失、背側の遺伝子発現領域が拡大しており、Six1の欠損が耳胞のパターン形成に重大な影響を与えたことを明確にした。 (2)後腎間葉細胞を用いてSix1およびSix4タンパク質の標的遺伝子候補を同定した。Six1では活性化されるがSix4では活性化が弱い遺伝子、Six1では弱く抑制されるが、Six4では強く抑制される遺伝子、両者で同様に活性化される遺伝子がそれぞれ見つかった。標的遺伝子候補の中に、その欠損が腎臓や耳の形成異常につながることが知られた遺伝子も含まれていた。 (3)VP16-Six5 (野生型)およびVP16-Six5W241R (変異型)の組換えアデノウイルスを、ヒト顆粒膜細胞株KGNに感染させ、マイクロアレーに対する競合ハイプリダイゼーションを行い、野生型と変異型とで2倍以上発現レベルが異なる遺伝子を標的候補として同定した。アレイ上にスポットされた12,814遺伝子の内の2.4%、310遺伝子が標的候補として同定できた。不妊症や遺伝子欠損マウスの表現型から卵胞の形成や機能に関与することが既に知られており、性腺機能低下症との関連が強く示唆される遺伝子が標的遺伝子として同定された。
  • Developmental Program and Genetic Disease by Six family genes.
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2000 -2002 
    Author : KAWAKAMI Kiyoshi, IKEDA Keiko, SATO Shigeru, OZAKI Hidenori
    This study aims to reveal roles of Six family genes in development, to elucidate gene network including Six and involvement of Six genes in pathology of myotonic dystrophy (DM1). We performed analyses of Six gene defective mice, screening of target genes of Six proteins and analyses of molecular function of Eya and Dach protein that are cooperative factors of Six protein. 1 Six4/Six5 double knockout mice die within several hours after birth but we could not find any apparent anatomical anomalies. Six1 gene defective mice die just after birth and showed defective formation of inner ear, nose, kidney and thymus. The morphological abnormalities were noted from E10-11. Six1 gene is suggested to be essential for the formation of these organs. 2 Target genes of Six5 proteins were identified. Transcription factors, signaling molecules and its receptors that are expressed during mesoderm differentiation were identified as putative target in P19 cells. Transcription factors and signaling molecules in nervous systems, transporters and receptor proteins of neural transmitters. In myoblasts, genes including myogenin, myosin, troponin, acetylcholine receptors that arespecific to skeletal muscle were identified. In lens epithelial cells, genes that had been shown to be involved in cataractogenesis were identified. It is suggested that altered regulation of these target genes leads to some symptoms of DM1. 3 We revealed that cooperative activation by GAL4-Eya and Dach is mediated through CBP. CBP bound to an immobilized chromatin template only in the presence of both GAL4-Eya and Dach. We also found that Dach can bind to chromatin as well as DNA regardless of the presence of GAL4-Eya protein. The binding affinity to chromatin was higher than that to naked DNA. The conserved DD1 domain of Dach is responsible for the DNA binding activity.
  • 骨格筋形成を支配する遺伝プログラムの起源を探る
    Date (from‐to) : 2000/04 -2001/03 
    Author : 佐藤滋
  • 日本学術振興会:科学研究費助成事業 特定領域研究(A)
    Date (from‐to) : 2001 -2001 
    Author : 佐藤 滋
  • 日本学術振興会:科学研究費助成事業 奨励研究(A)
    Date (from‐to) : 2000 -2001 
    Author : 佐藤 滋
    SIX5遺伝子の発現量低下と筋緊張性ジストロフィー1型(DM1)病態との関わりを明らかにするためには、転写因子SIX5によって発現が制御される標的遺伝子の同定が不可欠である。今年度は、活性化型Six5(VP16-Six5wt)をアデノウイルスベクターによりP19細胞で過剰発現させ、cDNAアレーを使って同定した標的候補遺伝子の1つ、IGFシグナル制御因子をコードするIgfbp5遺伝子について詳細な解析を行った。まずIgfbp5遺伝子プロモーター上のSix5結合部位をレポータージーン解析、種々のin vitro結合実験により明らかにした。Six5は進化的に保存されたGCTCAAATTGCという配列(転写開始点の上流-72bpに位置する)に結合することがわかった。既知の標的遺伝子(myogenin、Atpla1)との比較からSix5結合コンセンサス配列(TCARRTTNC)を提唱することができた。またSix5欠損マウス繊維芽細胞におけるIgfbp5の発現レベルは1/2以下に低下しており、生体内でもSix5がIgfbp5遺伝子の転写活性化に関与することが確認された。Igf2遺伝子についても同様な結果が得られた。次にDM1患者由来の繊維芽細胞を骨格筋に分化誘導し、その過程におけるIGFBP5遺伝子発現量の変動を調べた。正常細胞では約2倍の発現増加が観察されたが、3種類の患者由来細胞では発現量はいずれも低下しており、IGFBP5遺伝子の制御の様相が変化していることが示された。本研究により中胚葉、体節、骨格筋、いくつかの筋特異的遺伝子、神経系で発現する遺伝子がSix5標的遺伝子として同定された。以上によりSix5はこれら標的遺伝子の制御を介して中胚葉系の組織、神経組織の構築と機能に関わるタンパク質であり、複雑なDM1症状の一部に関与する可能性が強く示唆された。
  • 筋緊張性ジストロフィーの原因遺伝子の探索
    Date (from‐to) : 1999/04 -2000/03 
    Author : 佐藤 滋
  • Phylogenetic analysis of pigment cell differentiation
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for international Scientific Research
    Date (from‐to) : 1996 -1998 
    Author : YAMAMAOTO Hiroaki, COLIN Goding
    The main purpose of this project was to analyze phylogenetically the molecular mechanisms of pigment cell differentiation. The first step was to clone ascidian homologues for vertebrate genes involved in differentiation of pigment cells. Then, we analyzed the gene structures from phylogenetic view points. Their expression patterns were also analyzed. We obtained the following results. a. Putative ascidian tyrosinase gene encoding a key enzyme essential for melanin biosynthesis was cloned and their expression patterns were analyzed. b. Putative ascidian tyrosinase-related protein gene was also cloned. This gene showed the very early onset of expression in the course of ascidian development similar to those of vertebrate homologues. c. We identified several cis-acting elements in their regulatory regions. d. Putative ascidian MITF(microphthalmia-associated transcription factor) gene was cloned.Vertebrate MITF is known to activate expression of tyrosinase and its related genes. We had found that MITF-M is an essential isoform to allow differentiation of melanocyte from neural crest cells in vertebrates. Ascidian MITF homologue can not express the M-isoform. e. Ascidian MITF homologue can transactivate both ascidian tyrosinase and tyrosinase-related protein genes but also vertebrate tyrosinase and TRP genes. On the other hand, only one of vertebrate MITF isoforms can transactivate the ascidian TRP gene.
  • 色素細胞誕生の分子機構に関する研究
    日本学術振興会:科学研究費助成事業 特別研究員奨励費
    Date (from‐to) : 1996 -1998 
    Author : 佐藤 滋

Teaching Experience

  • Developental BiologyDevelopental Biology Jichi Medical University
  • Molecular BiologyMolecular Biology Jichi Medical University
  • Molecular Cell BiologyMolecular Cell Biology Jichi Medical University

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