1
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Kikuchi M, Yoshimoto M, Ishikawa T, Kanda Y, Mori K, Nishimura T, Tanaka M. Sexually dimorphic dynamics of the microtubule network in medaka (Oryzias latipes) germ cells. Development 2024; 151:dev201840. [PMID: 38471539 PMCID: PMC10984276 DOI: 10.1242/dev.201840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 02/05/2024] [Indexed: 03/14/2024]
Abstract
Gametogenesis is the process through which germ cells differentiate into sexually dimorphic gametes, eggs and sperm. In the teleost fish medaka (Oryzias latipes), a germ cell-intrinsic sex determinant, foxl3, triggers germline feminization by activating two genetic pathways that regulate folliculogenesis and meiosis. Here, we identified a pathway involving a dome-shaped microtubule structure that may be the basis of oocyte polarity. This structure was first established in primordial germ cells in both sexes, but was maintained only during oogenesis and was destabilized in differentiating spermatogonia under the influence of Sertoli cells expressing dmrt1. Although foxl3 was dispensable for this pathway, dazl was involved in the persistence of the microtubule dome at the time of gonocyte development. In addition, disruption of the microtubule dome caused dispersal of bucky ball RNA, suggesting the structure may be prerequisite for the Balbiani body. Collectively, the present findings provide mechanistic insight into the establishment of sex-specific polarity through the formation of a microtubule structure in germ cells, as well as clarifying the genetic pathways implementing oocyte-specific characteristics.
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Affiliation(s)
- Mariko Kikuchi
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Miyo Yoshimoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Tokiro Ishikawa
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yuto Kanda
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Kazutoshi Mori
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Toshiya Nishimura
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Minoru Tanaka
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
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2
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Bardhan S, Bhargava N, Dighe S, Vats N, Naganathan SR. Emergence of a left-right symmetric body plan in vertebrate embryos. Curr Top Dev Biol 2024; 159:310-342. [PMID: 38729680 DOI: 10.1016/bs.ctdb.2024.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2024]
Abstract
External bilateral symmetry is a prevalent feature in vertebrates, which emerges during early embryonic development. To begin with, vertebrate embryos are largely radially symmetric before transitioning to bilaterally symmetry, after which, morphogenesis of various bilateral tissues (e.g somites, otic vesicle, limb bud), and structures (e.g palate, jaw) ensue. While a significant amount of work has probed the mechanisms behind symmetry breaking in the left-right axis leading to asymmetric positioning of internal organs, little is known about how bilateral tissues emerge at the same time with the same shape and size and at the same position on the two sides of the embryo. By discussing emergence of symmetry in many bilateral tissues and structures across vertebrate model systems, we highlight that understanding symmetry establishment is largely an open field, which will provide deep insights into fundamental problems in developmental biology for decades to come.
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Affiliation(s)
- Siddhartha Bardhan
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Nandini Bhargava
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Swarali Dighe
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Neha Vats
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Sundar Ram Naganathan
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India.
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3
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Šimková K, Naraine R, Vintr J, Soukup V, Šindelka R. RNA localization during early development of the axolotl. Front Cell Dev Biol 2023; 11:1260795. [PMID: 37928901 PMCID: PMC10620976 DOI: 10.3389/fcell.2023.1260795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 09/26/2023] [Indexed: 11/07/2023] Open
Abstract
The asymmetric localization of biomolecules is critical for body plan development. One of the most popular model organisms for early embryogenesis studies is Xenopus laevis but there is a lack of information in other animal species. Here, we compared the early development of two amphibian species-the frog X. laevis and the axolotl Ambystoma mexicanum. This study aimed to identify asymmetrically localized RNAs along the animal-vegetal axis during the early development of A. mexicanum. For that purpose, we performed spatial transcriptome-wide analysis at low resolution, which revealed dynamic changes along the animal-vegetal axis classified into the following categories: profile alteration, de novo synthesis and degradation. Surprisingly, our results showed that many of the vegetally localized genes, which are important for germ cell development, are degraded during early development. Furthermore, we assessed the motif presence in UTRs of degraded mRNAs and revealed the enrichment of several motifs in RNAs of germ cell markers. Our results suggest novel reorganization of the transcriptome during embryogenesis of A. mexicanum to converge to the similar developmental pattern as the X. laevis.
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Affiliation(s)
- Kateřina Šimková
- Laboratory of Gene Expression, Institute of Biotechnology of the Czech Academy of Sciences, Vestec, Czechia
| | - Ravindra Naraine
- Laboratory of Gene Expression, Institute of Biotechnology of the Czech Academy of Sciences, Vestec, Czechia
| | - Jan Vintr
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Vladimír Soukup
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Radek Šindelka
- Laboratory of Gene Expression, Institute of Biotechnology of the Czech Academy of Sciences, Vestec, Czechia
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4
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Nair S, Welch EL, Moravec CE, Trevena RL, Hansen CL, Pelegri F. The midbody component Prc1-like is required for microtubule reorganization during cytokinesis and dorsal determinant segregation in the early zebrafish embryo. Development 2023; 150:dev200564. [PMID: 36789950 PMCID: PMC10112900 DOI: 10.1242/dev.200564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 01/10/2023] [Indexed: 02/16/2023]
Abstract
We show that the zebrafish maternal-effect mutation too much information (tmi) corresponds to zebrafish prc1-like (prc1l), which encodes a member of the MAP65/Ase1/PRC1 family of microtubule-associated proteins. Embryos from tmi homozygous mutant mothers display cytokinesis defects in meiotic and mitotic divisions in the early embryo, indicating that Prc1l has a role in midbody formation during cell division at the egg-to-embryo transition. Unexpectedly, maternal Prc1l function is also essential for the reorganization of vegetal pole microtubules required for the segregation of dorsal determinants. Whereas Prc1 is widely regarded to crosslink microtubules in an antiparallel conformation, our studies provide evidence for an additional function of Prc1l in the bundling of parallel microtubules in the vegetal cortex of the early embryo during cortical rotation and prior to mitotic cycling. These findings highlight common yet distinct aspects of microtubule reorganization that occur during the egg-to-embryo transition, driven by maternal product for the midbody component Prc1l and required for embryonic cell division and pattern formation.
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Affiliation(s)
- Sreelaja Nair
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra, India
| | - Elaine L. Welch
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Cara E. Moravec
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ryan L. Trevena
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Christina L. Hansen
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
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5
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Jamieson-Lucy AH, Kobayashi M, James Aykit Y, Elkouby YM, Escobar-Aguirre M, Vejnar CE, Giraldez AJ, Mullins MC. A proteomics approach identifies novel resident zebrafish Balbiani body proteins Cirbpa and Cirbpb. Dev Biol 2022; 484:1-11. [PMID: 35065906 PMCID: PMC8967276 DOI: 10.1016/j.ydbio.2022.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 01/11/2022] [Accepted: 01/13/2022] [Indexed: 01/17/2023]
Abstract
The Balbiani body (Bb) is the first marker of polarity in vertebrate oocytes. The Bb is a conserved structure found in diverse animals including insects, fish, amphibians, and mammals. During early zebrafish oogenesis, the Bb assembles as a transient aggregate of mRNA, proteins, and membrane-bound organelles at the presumptive vegetal side of the oocyte. As the early oocyte develops, the Bb appears to grow slowly, until at the end of stage I of oogenesis it disassembles and deposits its cargo of localized mRNAs and proteins. In fish and frogs, this cargo includes the germ plasm as well as gene products required to specify dorsal tissues of the future embryo. We demonstrate that the Bb is a stable, solid structure that forms a size exclusion barrier similar to other biological hydrogels. Despite its central role in oocyte polarity, little is known about the mechanism behind the Bb's action. Analysis of the few known protein components of the Bb is insufficient to explain how the Bb assembles, translocates, and disassembles. We isolated Bbs from zebrafish oocytes and performed mass spectrometry to define the Bb proteome. We successfully identified 77 proteins associated with the Bb sample, including known Bb proteins and novel RNA-binding proteins. In particular, we identified Cirbpa and Cirbpb, which have both an RNA-binding domain and a predicted self-aggregation domain. In stage I oocytes, Cirbpa and Cirbpb localize to the Bb rather than the nucleus (as in somatic cells), indicating that they may have a specialized function in the germ line. Both the RNA-binding domain and the self-aggregation domain are sufficient to localize to the Bb, suggesting that Cirbpa and Cirbpb interact with more than just their mRNA targets within the Bb. We propose that Cirbp proteins crosslink mRNA cargo and proteinaceous components of the Bb as it grows. Beyond Cirbpa and Cirbpb, our proteomics dataset presents many candidates for further study, making it a valuable resource for building a comprehensive mechanism for Bb function at a protein level.
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Affiliation(s)
- Allison H Jamieson-Lucy
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Manami Kobayashi
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Y James Aykit
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Yaniv M Elkouby
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Matias Escobar-Aguirre
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Charles E Vejnar
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Antonio J Giraldez
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Mary C Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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6
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Jones WD, Mullins MC. Cell signaling pathways controlling an axis organizing center in the zebrafish. Curr Top Dev Biol 2022; 150:149-209. [DOI: 10.1016/bs.ctdb.2022.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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7
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Moravec CE, Voit GC, Otterlee J, Pelegri F. Identification of maternal-effect genes in zebrafish using maternal crispants. Development 2021; 148:dev199536. [PMID: 34463742 PMCID: PMC8543149 DOI: 10.1242/dev.199536] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 08/19/2021] [Indexed: 01/25/2023]
Abstract
In animals, early development is dependent on a pool of maternal factors, both RNA and proteins, which are required for basic cellular processes and cell differentiation until zygotic genome activation. The role of the majority of these maternally expressed factors is not fully understood. By exploiting the biallelic editing ability of CRISPR-Cas9, we identify and characterize maternal-effect genes in a single generation, using a maternal crispant technique. We validated the ability to generate biallelic mutations in the germ line by creating maternal crispants that phenocopied previously characterized maternal-effect genes: birc5b, tmi and mid1ip1. Additionally, by targeting maternally expressed genes of unknown function in zebrafish, we identified two maternal-effect zebrafish genes, kpna7 and fhdc3. The genetic identity of these maternal crispants was confirmed by sequencing haploid progeny from F0 females, which allowed the analysis of newly induced lesions in the maternal germ line. Our studies show that maternal crispants allow for the effective identification and primary characterization of maternal-effect genes in a single generation, facilitating the reverse genetics analysis of maternal factors that drive embryonic development.
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Affiliation(s)
| | | | | | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin-Madison, WI 53706, USA
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8
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Moravec CE, Pelegri F. The role of the cytoskeleton in germ plasm aggregation and compaction in the zebrafish embryo. Curr Top Dev Biol 2020; 140:145-179. [PMID: 32591073 DOI: 10.1016/bs.ctdb.2020.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The transmission of genetic information from one generation to another is crucial for survival of animal species. This is accomplished by the induction of primordial germ cells (PGCs) that will eventually establish the germline. In some animals the germline is induced by signals in gastrula, whereas in others it is specified by inheritance of maternal determinants, known as germ plasm. In zebrafish, aggregation and compaction of maternally derived germ plasm during the first several embryonic cell cycles is essential for generation of PGCs. These processes are controlled by cellular functions associated with the cellular division apparatus. Ribonucleoparticles containing germ plasm components are bound to both the ends of astral microtubules and a dynamic F-actin network through a mechanism integrated with that which drives the cell division program. In this chapter we discuss the role that modifications of the cell division apparatus, including the cytoskeleton and cytoskeleton-associated proteins, play in the regulation of zebrafish germ plasm assembly.
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Affiliation(s)
- Cara E Moravec
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, United States
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, United States.
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9
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Fuentes R, Tajer B, Kobayashi M, Pelliccia JL, Langdon Y, Abrams EW, Mullins MC. The maternal coordinate system: Molecular-genetics of embryonic axis formation and patterning in the zebrafish. Curr Top Dev Biol 2020; 140:341-389. [PMID: 32591080 DOI: 10.1016/bs.ctdb.2020.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Axis specification of the zebrafish embryo begins during oogenesis and relies on proper formation of well-defined cytoplasmic domains within the oocyte. Upon fertilization, maternally-regulated cytoplasmic flow and repositioning of dorsal determinants establish the coordinate system that will build the structure and developmental body plan of the embryo. Failure of specific genes that regulate the embryonic coordinate system leads to catastrophic loss of body structures. Here, we review the genetic principles of axis formation and discuss how maternal factors orchestrate axis patterning during zebrafish early embryogenesis. We focus on the molecular identity and functional contribution of genes controlling critical aspects of oogenesis, egg activation, blastula, and gastrula stages. We examine how polarized cytoplasmic domains form in the oocyte, which set off downstream events such as animal-vegetal polarity and germ line development. After gametes interact and form the zygote, cytoplasmic segregation drives the animal-directed reorganization of maternal determinants through calcium- and cell cycle-dependent signals. We also summarize how maternal genes control dorsoventral, anterior-posterior, mesendodermal, and left-right cell fate specification and how signaling pathways pattern these axes and tissues during early development to instruct the three-dimensional body plan. Advances in reverse genetics and phenotyping approaches in the zebrafish model are revealing positional patterning signatures at the single-cell level, thus enhancing our understanding of genotype-phenotype interactions in axis formation. Our emphasis is on the genetic interrogation of novel and specific maternal regulatory mechanisms of axis specification in the zebrafish.
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Affiliation(s)
- Ricardo Fuentes
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
| | - Benjamin Tajer
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | - Manami Kobayashi
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | - Jose L Pelliccia
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | | | - Elliott W Abrams
- Department of Biology, Purchase College, State University of New York, Harrison, NY, United States
| | - Mary C Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States.
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10
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Abrams EW, Fuentes R, Marlow FL, Kobayashi M, Zhang H, Lu S, Kapp L, Joseph SR, Kugath A, Gupta T, Lemon V, Runke G, Amodeo AA, Vastenhouw NL, Mullins MC. Molecular genetics of maternally-controlled cell divisions. PLoS Genet 2020; 16:e1008652. [PMID: 32267837 PMCID: PMC7179931 DOI: 10.1371/journal.pgen.1008652] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 04/23/2020] [Accepted: 02/04/2020] [Indexed: 02/01/2023] Open
Abstract
Forward genetic screens remain at the forefront of biology as an unbiased approach for discovering and elucidating gene function at the organismal and molecular level. Past mutagenesis screens targeting maternal-effect genes identified a broad spectrum of phenotypes ranging from defects in oocyte development to embryonic patterning. However, earlier vertebrate screens did not reach saturation, anticipated classes of phenotypes were not uncovered, and technological limitations made it difficult to pinpoint the causal gene. In this study, we performed a chemically-induced maternal-effect mutagenesis screen in zebrafish and identified eight distinct mutants specifically affecting the cleavage stage of development and one cleavage stage mutant that is also male sterile. The cleavage-stage phenotypes fell into three separate classes: developmental arrest proximal to the mid blastula transition (MBT), irregular cleavage, and cytokinesis mutants. We mapped each mutation to narrow genetic intervals and determined the molecular basis for two of the developmental arrest mutants, and a mutation causing male sterility and a maternal-effect mutant phenotype. One developmental arrest mutant gene encodes a maternal specific Stem Loop Binding Protein, which is required to maintain maternal histone levels. The other developmental arrest mutant encodes a maternal-specific subunit of the Minichromosome Maintenance Protein Complex, which is essential for maintaining normal chromosome integrity in the early blastomeres. Finally, we identify a hypomorphic allele of Polo-like kinase-1 (Plk-1), which results in a male sterile and maternal-effect phenotype. Collectively, these mutants expand our molecular-genetic understanding of the maternal regulation of early embryonic development in vertebrates.
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Affiliation(s)
- Elliott W. Abrams
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Purchase College, The State University of New York, Purchase, New York, United States of America
| | - Ricardo Fuentes
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Florence L. Marlow
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Manami Kobayashi
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Hong Zhang
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Sumei Lu
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Lee Kapp
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Shai R. Joseph
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Amy Kugath
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Tripti Gupta
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Virginia Lemon
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Greg Runke
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Amanda A. Amodeo
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | | | - Mary C. Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
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11
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Izumi H, Gen K, Lokman PM, Hagihara S, Horiuchi M, Tanaka T, Ijiri S, Adachi S. Maternal transcripts in good and poor quality eggs from Japanese eel,
Anguilla japonica
—their identification by large‐scale quantitative analysis. Mol Reprod Dev 2019; 86:1846-1864. [DOI: 10.1002/mrd.23273] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 08/29/2019] [Indexed: 01/16/2023]
Affiliation(s)
- Hikari Izumi
- Division of Marine Life ScienceHokkaido University Hokkaido Japan
| | - Koichiro Gen
- Seikai National Fisheries Research InstituteFisheries Research Agency Nagasaki Japan
| | - P. Mark Lokman
- Department of ZoologyUniversity of Otago Dunedin New Zealand
| | - Seishi Hagihara
- Division of Marine Life ScienceHokkaido University Hokkaido Japan
| | - Moemi Horiuchi
- Division of Marine Life ScienceHokkaido University Hokkaido Japan
| | - Toshiomi Tanaka
- Hamanako BranchShizuoka Prefectural Research Institute of Fishery Shizuoka Japan
| | - Shigeho Ijiri
- Division of Marine Life ScienceHokkaido University Hokkaido Japan
| | - Shinji Adachi
- Division of Marine Life ScienceHokkaido University Hokkaido Japan
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12
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Abstract
Soon after fertilization the zebrafish embryo generates the pool of cells that will give rise to the germline and the three somatic germ layers of the embryo (ectoderm, mesoderm and endoderm). As the basic body plan of the vertebrate embryo emerges, evolutionarily conserved developmental signaling pathways, including Bmp, Nodal, Wnt, and Fgf, direct the nearly totipotent cells of the early embryo to adopt gene expression profiles and patterns of cell behavior specific to their eventual fates. Several decades of molecular genetics research in zebrafish has yielded significant insight into the maternal and zygotic contributions and mechanisms that pattern this vertebrate embryo. This new understanding is the product of advances in genetic manipulations and imaging technologies that have allowed the field to probe the cellular, molecular and biophysical aspects underlying early patterning. The current state of the field indicates that patterning is governed by the integration of key signaling pathways and physical interactions between cells, rather than a patterning system in which distinct pathways are deployed to specify a particular cell fate. This chapter focuses on recent advances in our understanding of the genetic and molecular control of the events that impart cell identity and initiate the patterning of tissues that are prerequisites for or concurrent with movements of gastrulation.
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Affiliation(s)
- Florence L Marlow
- Icahn School of Medicine Mount Sinai Department of Cell, Developmental and Regenerative Biology, New York, NY, United States.
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13
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Jamieson-Lucy A, Mullins MC. The vertebrate Balbiani body, germ plasm, and oocyte polarity. Curr Top Dev Biol 2019; 135:1-34. [DOI: 10.1016/bs.ctdb.2019.04.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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14
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Massive cytoplasmic transport and microtubule organization in fertilized chordate eggs. Dev Biol 2018; 448:154-160. [PMID: 30521810 DOI: 10.1016/j.ydbio.2018.11.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 11/24/2018] [Accepted: 11/30/2018] [Indexed: 01/13/2023]
Abstract
Eggs have developed their own strategies for early development. Amphibian, teleost fish, and ascidian eggs show cortical rotation and an accompanying structure, a cortical parallel microtubule (MT) array, during the one-cell embryonic stage. Cortical rotation is thought to relocate maternal deposits to a certain compartment of the egg and to polarize the embryo. The common features and differences among chordate eggs as well as localized maternal proteins and mRNAs that are related to the organization of MT structures are described in this review. Furthermore, recent studies report progress in elucidating the molecular nature and functions of the noncentrosomal MT organizing center (ncMTOC). The parallel array of MT bundles is presumably organized by ncMTOCs; therefore, the mechanism of ncMTOC control is likely inevitable for these species. Thus, the molecules related to the ncMTOC provide clues for understanding the mechanisms of early developmental systems, which ultimately determine the embryonic axis.
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15
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Fuentes R, Letelier J, Tajer B, Valdivia LE, Mullins MC. Fishing forward and reverse: Advances in zebrafish phenomics. Mech Dev 2018; 154:296-308. [PMID: 30130581 PMCID: PMC6289646 DOI: 10.1016/j.mod.2018.08.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 08/06/2018] [Accepted: 08/17/2018] [Indexed: 12/15/2022]
Abstract
Understanding how the genome instructs the phenotypic characteristics of an organism is one of the major scientific endeavors of our time. Advances in genetics have progressively deciphered the inheritance, identity and biological relevance of genetically encoded information, contributing to the rise of several, complementary omic disciplines. One of them is phenomics, an emergent area of biology dedicated to the systematic multi-scale analysis of phenotypic traits. This discipline provides valuable gene function information to the rapidly evolving field of genetics. Current molecular tools enable genome-wide analyses that link gene sequence to function in multi-cellular organisms, illuminating the genome-phenome relationship. Among vertebrates, zebrafish has emerged as an outstanding model organism for high-throughput phenotyping and modeling of human disorders. Advances in both systematic mutagenesis and phenotypic analyses of embryonic and post-embryonic stages in zebrafish have revealed the function of a valuable collection of genes and the general structure of several complex traits. In this review, we summarize multiple large-scale genetic efforts addressing parental, embryonic, and adult phenotyping in the zebrafish. The genetic and quantitative tools available in the zebrafish model, coupled with the broad spectrum of phenotypes that can be assayed, make it a powerful model for phenomics, well suited for the dissection of genotype-phenotype associations in development, physiology, health and disease.
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Affiliation(s)
- Ricardo Fuentes
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Joaquín Letelier
- Centro Andaluz de Biología del Desarrollo (CSIC/UPO/JA), Seville, Spain; Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Benjamin Tajer
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Leonardo E Valdivia
- Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile.
| | - Mary C Mullins
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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16
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Yan L, Chen J, Zhu X, Sun J, Wu X, Shen W, Zhang W, Tao Q, Meng A. Maternal Huluwa dictates the embryonic body axis through β-catenin in vertebrates. Science 2018; 362:362/6417/eaat1045. [DOI: 10.1126/science.aat1045] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 09/27/2018] [Indexed: 12/26/2022]
Abstract
The vertebrate body is formed by cell movements and shape change during embryogenesis. It remains undetermined which maternal signals govern the formation of the dorsal organizer and the body axis. We found that maternal depletion of huluwa, a previously unnamed gene, causes loss of the dorsal organizer, the head, and the body axis in zebrafish and Xenopus embryos. Huluwa protein is found on the plasma membrane of blastomeres in the future dorsal region in early zebrafish blastulas. Huluwa has strong dorsalizing and secondary axis–inducing activities, which require β-catenin but can function independent of Wnt ligand/receptor signaling. Mechanistically, Huluwa binds to and promotes the tankyrase-mediated degradation of Axin. Therefore, maternal Huluwa is an essential determinant of the dorsal organizer and body axis in vertebrate embryos.
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17
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Fuentes R, Mullins MC, Fernández J. Formation and dynamics of cytoplasmic domains and their genetic regulation during the zebrafish oocyte-to-embryo transition. Mech Dev 2018; 154:259-269. [PMID: 30077623 DOI: 10.1016/j.mod.2018.08.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 08/01/2018] [Indexed: 12/13/2022]
Abstract
Establishment and movement of cytoplasmic domains is of great importance for the emergence of cell polarity, germline segregation, embryonic axis specification and correct sorting of organelles and macromolecules into different embryonic cells. The zebrafish oocyte, egg and zygote are valuable material for the study of cytoplasmic domains formation and dynamics during development. In this review we examined how cytoplasmic domains form and are relocated during zebrafish early embryogenesis. Distinct cortical cytoplasmic domains (also referred to as ectoplasm domains) form first during early oogenesis by the localization of mRNAs to the vegetal or animal poles of the oocyte or radially throughout the cortex. Cytoplasmic segregation in the late oocyte relocates non-cortical cytoplasm (endoplasm) into the preblastodisc and yolk cell. The preblastodisc is a precursor to the blastodisc, which gives rise to the blastoderm and most the future embryo. After egg activation, the blastodisc enlarges by transport of cytoplasm from the yolk cell to the animal pole, along defined pathways or streamers that include a complex cytoskeletal meshwork and cytoplasmic movement at different speeds. A powerful actin ring, assembled at the margin of the blastodisc, appears to drive the massive streaming of cytoplasm. The fact that the mechanism(s) leading to the formation and relocation of cytoplasmic domains are affected in maternal-effect mutants indicates that these processes are under maternal control. Here, we also discuss why these mutants represent outstanding genetic entry points to investigate the genetic basis of cytoplasmic segregation. Functional studies, combined with the analysis of zebrafish mutants, generated by forward and reverse genetic strategies, are expected to decipher the molecular mechanism(s) by which the maternal factors regulate cytoplasmic movements during early vertebrate development.
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Affiliation(s)
- Ricardo Fuentes
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Mary C Mullins
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Juan Fernández
- Department of Biology, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
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18
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Winata CL, Korzh V. The translational regulation of maternal mRNAs in time and space. FEBS Lett 2018; 592:3007-3023. [PMID: 29972882 PMCID: PMC6175449 DOI: 10.1002/1873-3468.13183] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 06/29/2018] [Accepted: 06/29/2018] [Indexed: 12/16/2022]
Abstract
Since their discovery, the study of maternal mRNAs has led to the identification of mechanisms underlying their spatiotemporal regulation within the context of oogenesis and early embryogenesis. Following synthesis in the oocyte, maternal mRNAs are translationally silenced and sequestered into storage in cytoplasmic granules. At the same time, their unique distribution patterns throughout the oocyte and embryo are tightly controlled and connected to their functions in downstream embryonic processes. At certain points in oogenesis and early embryogenesis, maternal mRNAs are translationally activated to perform their functions in a timely manner. The cytoplasmic polyadenylation machinery is responsible for the translational activation of maternal mRNAs, and its role in initiating the maternal to zygotic transition events has recently come to light. Here, we summarize the current knowledge on maternal mRNA regulation, with particular focus on cytoplasmic polyadenylation as a mechanism for translational regulation.
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Affiliation(s)
- Cecilia Lanny Winata
- International Institute of Molecular and Cell Biology in Warsaw, Poland.,Max-Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Vladimir Korzh
- International Institute of Molecular and Cell Biology in Warsaw, Poland
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19
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Butler AM, Owens DA, Wang L, King ML. A novel role for sox7 in Xenopus early primordial germ cell development: mining the PGC transcriptome. Development 2018; 145:dev.155978. [PMID: 29158442 DOI: 10.1242/dev.155978] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 11/06/2017] [Indexed: 12/26/2022]
Abstract
Xenopus primordial germ cells (PGCs) are determined by the presence of maternally derived germ plasm. Germ plasm components both protect PGCs from somatic differentiation and begin a unique gene expression program. Segregation of the germline from the endodermal lineage occurs during gastrulation, and PGCs subsequently initiate zygotic transcription. However, the gene network(s) that operate to both preserve and promote germline differentiation are poorly understood. Here, we utilized RNA-sequencing analysis to comprehensively interrogate PGC and neighboring endoderm cell mRNAs after lineage segregation. We identified 1865 transcripts enriched in PGCs compared with endoderm cells. We next compared the PGC-enriched transcripts with previously identified maternal, vegetally enriched transcripts and found that ∼38% of maternal transcripts were enriched in PGCs, including sox7 PGC-directed sox7 knockdown and overexpression studies revealed an early requirement for sox7 in germ plasm localization, zygotic transcription and PGC number. We identified pou5f3.3 as the most highly expressed and enriched POU5F1 homolog in PGCs. We compared the Xenopus PGC transcriptome with human PGC transcripts and showed that 80% of genes are conserved, underscoring the potential usefulness of Xenopus for understanding human germline specification.
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Affiliation(s)
- Amanda M Butler
- Department of Cell Biology, University of Miami Miller School of Medicine, 1011 NW 15th St, Miami, FL 33136, USA
| | - Dawn A Owens
- Department of Cell Biology, University of Miami Miller School of Medicine, 1011 NW 15th St, Miami, FL 33136, USA
| | - Lingyu Wang
- Department of Biology, University of Miami, Coral Gables, FL 33124, USA
| | - Mary Lou King
- Department of Cell Biology, University of Miami Miller School of Medicine, 1011 NW 15th St, Miami, FL 33136, USA
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20
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Hino H, Nakanishi A, Seki R, Aoki T, Yamaha E, Kawahara A, Shimizu T, Hibi M. Roles of maternal wnt8a transcripts in axis formation in zebrafish. Dev Biol 2017; 434:96-107. [PMID: 29208373 DOI: 10.1016/j.ydbio.2017.11.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 11/24/2017] [Accepted: 11/29/2017] [Indexed: 01/05/2023]
Abstract
In early zebrafish development, the program for dorsal axis formation begins soon after fertilization. Previous studies suggested that dorsal determinants (DDs) localize to the vegetal pole, and are transported to the dorsal blastomeres in a microtubule-dependent manner. The DDs activate the canonical Wnt pathway and induce dorsal-specific genes that are required for dorsal axis formation. Among wnt-family genes, only the wnt8a mRNA is reported to localize to the vegetal pole in oocytes and to induce the dorsal axis, suggesting that Wnt8a is a candidate DD. Here, to reveal the roles of maternal wnt8a, we generated wnt8a mutants by transcription activator-like effector nucleases (TALENs), and established zygotic, maternal, and maternal zygotic wnt8a mutants by germ-line replacement. Zebrafish wnt8a has two open reading frames (ORF1 and ORF2) that are tandemly located in the genome. Although the zygotic ORF1 or ORF2 wnt8a mutants showed little or no axis-formation defects, the ORF1/2 compound mutants showed antero-dorsalized phenotypes, indicating that ORF1 and ORF2 have redundant roles in ventrolateral and posterior tissue formation. Unexpectedly, the maternal wnt8a ORF1/2 mutants showed no axis-formation defects. The maternal-zygotic wnt8a ORF1/2 mutants showed more severe antero-dorsalized phenotypes than the zygotic mutants. These results indicated that maternal wnt8a is dispensable for the initial dorsal determination, but cooperates with zygotic wnt8a for ventrolateral and posterior tissue formation. Finally, we re-examined the maternal wnt genes and found that Wnt6a is an alternative candidate DD.
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Affiliation(s)
- Hiromu Hino
- Laboratory of Organogenesis and Organ Function, Bioscience and Biotechnology Center, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8601, Japan; Division of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Akiko Nakanishi
- Laboratory of Organogenesis and Organ Function, Bioscience and Biotechnology Center, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Ryoko Seki
- Laboratory of Organogenesis and Organ Function, Bioscience and Biotechnology Center, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Tsubasa Aoki
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Etsuro Yamaha
- Nanae Fresh Water Laboratory, Field Science Center for Northern Biosphere, Hokkaido University, Nanae, Kameda, Hokkaido 041-1105, Japan
| | - Atsuo Kawahara
- Laboratory for Developmental Biology, Center for Medical Education and Sciences, Graduate School of Medical Science, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| | - Takashi Shimizu
- Laboratory of Organogenesis and Organ Function, Bioscience and Biotechnology Center, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8601, Japan; Division of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Masahiko Hibi
- Laboratory of Organogenesis and Organ Function, Bioscience and Biotechnology Center, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8601, Japan; Division of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan.
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21
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Oh D, Houston DW. Role of maternal Xenopus syntabulin in germ plasm aggregation and primordial germ cell specification. Dev Biol 2017; 432:237-247. [PMID: 29037933 DOI: 10.1016/j.ydbio.2017.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 09/20/2017] [Accepted: 10/11/2017] [Indexed: 01/04/2023]
Abstract
The localization and organization of mitochondria- and ribonucleoprotein granule-rich germ plasm is essential for many aspects of germ cell development. In Xenopus, germ plasm is maternally inherited and is required for the specification of primordial germ cells (PGCs). Germ plasm is aggregated into larger patches during egg activation and cleavage and is ultimately translocated perinuclearly during gastrulation. Although microtubule dynamics and a kinesin (Kif4a) have been implicated in Xenopus germ plasm localization, little is known about how germ plasm distribution is regulated. Here, we identify a role for maternal Xenopus Syntabulin in the aggregation of germ plasm following fertilization. We show that depletion of sybu mRNA using antisense oligonucleotides injected into oocytes results in defects in the aggregation and perinuclear transport of germ plasm and subsequently in reduced PGC numbers. Using live imaging analysis, we also characterize a novel role for Sybu in the collection of germ plasm in vegetal cleavage furrows by surface contraction waves. Additionally, we show that a localized kinesin-like protein, Kif3b, is also required for germ plasm aggregation and that Sybu functionally interacts with Kif3b and Kif4a in germ plasm aggregation. Overall, these data suggest multiple coordinate roles for kinesins and adaptor proteins in controlling the localization and distribution of a cytoplasmic determinant in early development.
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Affiliation(s)
- Denise Oh
- The University of Iowa, Department of Biology, 257 BB, Iowa City, IA 52242-1324, USA
| | - Douglas W Houston
- The University of Iowa, Department of Biology, 257 BB, Iowa City, IA 52242-1324, USA.
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22
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Shao M, Wang M, Liu YY, Ge YW, Zhang YJ, Shi DL. Vegetally localised Vrtn functions as a novel repressor to modulate bmp2b transcription during dorsoventral patterning in zebrafish. Development 2017; 144:3361-3374. [PMID: 28928283 DOI: 10.1242/dev.152553] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 08/15/2017] [Indexed: 02/03/2023]
Abstract
The vegetal pole cytoplasm represents a crucial source of maternal dorsal determinants for patterning the dorsoventral axis of the early embryo. Removal of the vegetal yolk in the zebrafish fertilised egg before the completion of the first cleavage results in embryonic ventralisation, but removal of this part at the two-cell stage leads to embryonic dorsalisation. How this is achieved remains unknown. Here, we report a novel mode of maternal regulation of BMP signalling during dorsoventral patterning in zebrafish. We identify Vrtn as a novel vegetally localised maternal factor with dorsalising activity and rapid transport towards the animal pole region after fertilisation. Co-injection of vrtn mRNA with vegetal RNAs from different cleavage stages suggests the presence of putative vegetally localised Vrtn antagonists with slower animal pole transport. Thus, vegetal ablation at the two-cell stage could remove most of the Vrtn antagonists, and allows Vrtn to produce the dorsalising effect. Mechanistically, Vrtn binds a bmp2b regulatory sequence and acts as a repressor to inhibit its zygotic transcription. Analysis of maternal-zygotic vrtn mutants further shows that Vrtn is required to constrain excessive bmp2b expression in the margin. Our work unveils a novel maternal mechanism regulating zygotic BMP gradient in dorsoventral patterning.
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Affiliation(s)
- Ming Shao
- School of Life Science, Shandong University, 27 Shanda Nan road, Jinan 250100, China
| | - Min Wang
- School of Life Science, Shandong University, 27 Shanda Nan road, Jinan 250100, China
| | - Yuan-Yuan Liu
- School of Life Science, Shandong University, 27 Shanda Nan road, Jinan 250100, China
| | - Yi-Wen Ge
- School of Life Science, Shandong University, 27 Shanda Nan road, Jinan 250100, China
| | - Yan-Jun Zhang
- School of Life Science, Shandong University, 27 Shanda Nan road, Jinan 250100, China
| | - De-Li Shi
- School of Life Science, Shandong University, 27 Shanda Nan road, Jinan 250100, China .,Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR7622, IBPS-Developmental Biology Laboratory, 75005 Paris, France
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23
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Ishii H, Goto T, Nishikata T. Microtubule array observed in the posterior-vegetal cortex during cytoplasmic and cortical reorganization of the ascidian egg. Dev Growth Differ 2017; 59:648-656. [PMID: 28967684 DOI: 10.1111/dgd.12405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 08/27/2017] [Accepted: 08/27/2017] [Indexed: 12/27/2022]
Abstract
Body axis formation during embryogenesis results from asymmetric localization of maternal factors in the egg. Shortly before the first cleavage in ascidian eggs, cell polarity along the anteroposterior (A-P) axis is established and the cytoplasmic domain (myoplasm) relocates from the vegetal to the posterior region in a microtubule-dependent manner. Through immunostaining, tubulin accumulation during this reorganization is observable on the myoplasm cortex. However, more detailed morphological features of microtubules remain relatively unknown. In this study, we invented a new reagent that improves the immunostaining of cortical microtubules and successfully visualized a parallel array of thick microtubules. During reorganization, they covered nearly the entire myoplasm cortical region, beneath the posterior-vegetal cortex. We designated this microtubule array as CAMP (cortical array of microtubules in posterior vegetal region). During the late phase of reorganization, CAMP shrank and the myoplasm formed a crescent-like cytoplasmic domain. When the CAMP formation was inhibited by sodium azide, myoplasmic reorganization and A-P axis formation were both abolished, suggesting that CAMP is important for these two processes.
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Affiliation(s)
- Hirokazu Ishii
- Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Hyogo, 650-0047, Japan
| | - Toshiyuki Goto
- Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Hyogo, 650-0047, Japan
| | - Takahito Nishikata
- Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Hyogo, 650-0047, Japan
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24
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Microtubule-actin crosslinking factor 1 (Macf1) domain function in Balbiani body dissociation and nuclear positioning. PLoS Genet 2017; 13:e1006983. [PMID: 28880872 PMCID: PMC5605089 DOI: 10.1371/journal.pgen.1006983] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 09/19/2017] [Accepted: 08/17/2017] [Indexed: 12/31/2022] Open
Abstract
Animal-vegetal (AV) polarity of most vertebrate eggs is established during early oogenesis through the formation and disassembly of the Balbiani Body (Bb). The Bb is a structure conserved from insects to humans that appears as a large granule, similar to a mRNP granule composed of mRNA and proteins, that in addition contains mitochondria, ER and Golgi. The components of the Bb, which have amyloid-like properties, include germ cell and axis determinants of the embryo that are anchored to the vegetal cortex upon Bb disassembly. Our lab discovered in zebrafish the only gene known to function in Bb disassembly, microtubule-actin crosslinking factor 1a (macf1a). Macf1 is a conserved, giant multi-domain cytoskeletal linker protein that can interact with microtubules (MTs), actin filaments (AF), and intermediate filaments (IF). In macf1a mutant oocytes the Bb fails to dissociate, the nucleus is acentric, and AV polarity of the oocyte and egg fails to form. The cytoskeleton-dependent mechanism by which Macf1a regulates Bb mRNP granule dissociation was unknown. We found that disruption of AFs phenocopies the macf1a mutant phenotype, while MT disruption does not. We determined that cytokeratins (CK), a type of IF, are enriched in the Bb. We found that Macf1a localizes to the Bb, indicating a direct function in regulating its dissociation. We thus tested if Macf1a functions via its actin binding domain (ABD) and plectin repeat domain (PRD) to integrate cortical actin and Bb CK, respectively, to mediate Bb dissociation at the oocyte cortex. We developed a CRISPR/Cas9 approach to delete the exons encoding these domains from the macf1a endogenous locus, while maintaining the open reading frame. Our analysis shows that Macf1a functions via its ABD to mediate Bb granule dissociation and nuclear positioning, while the PRD is dispensable. We propose that Macf1a does not function via its canonical mechanism of linking two cytoskeletal systems together in dissociating the Bb. Instead our results suggest that Macf1a functions by linking one cytoskeletal system, cortical actin, to another structure, the Bb, where Macf1a is localized. Through this novel linking process, it dissociates the Bb at the oocyte cortex, thus specifying the AV axis of the oocyte and future egg. To our knowledge, this is also the first study to use genome editing to unravel the module-dependent function of a cytoskeletal linker. The totipotent egg of most vertebrates is polarized in a so called animal-vegetal axis that is essential to early embryonic development. The animal-vegetal axis is established in the early oocyte by the dissociation of the Balbiani Body (Bb). The Bb is a large RNA-protein granule, conserved from insects to mammals, that forms next to the oocyte nucleus and dissociates later at the oocyte cortex. Importantly, Bb dissociation at the oocyte cortex defines the future vegetal pole of the egg. Macf1a, a cytolinker, is the only factor known to regulate Bb dissociation. However, how the giant Macf1a protein with multiple functional domains can interact with the cytoskeleton to regulate Bb disassembly is unknown. Here, we unravel Macf1a function via interrogating, for the first time, individual macf1a-encoded domains of the gene in its normal chromosomal location for their requirement in Bb dissociation and ultimately in egg polarity establishment. The method presented here is applicable to other cytolinkers involved in human disease.
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25
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Houston DW. Vertebrate Axial Patterning: From Egg to Asymmetry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 953:209-306. [PMID: 27975274 PMCID: PMC6550305 DOI: 10.1007/978-3-319-46095-6_6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The emergence of the bilateral embryonic body axis from a symmetrical egg has been a long-standing question in developmental biology. Historical and modern experiments point to an initial symmetry-breaking event leading to localized Wnt and Nodal growth factor signaling and subsequent induction and formation of a self-regulating dorsal "organizer." This organizer forms at the site of notochord cell internalization and expresses primarily Bone Morphogenetic Protein (BMP) growth factor antagonists that establish a spatiotemporal gradient of BMP signaling across the embryo, directing initial cell differentiation and morphogenesis. Although the basics of this model have been known for some time, many of the molecular and cellular details have only recently been elucidated and the extent that these events remain conserved throughout vertebrate evolution remains unclear. This chapter summarizes historical perspectives as well as recent molecular and genetic advances regarding: (1) the mechanisms that regulate symmetry-breaking in the vertebrate egg and early embryo, (2) the pathways that are activated by these events, in particular the Wnt pathway, and the role of these pathways in the formation and function of the organizer, and (3) how these pathways also mediate anteroposterior patterning and axial morphogenesis. Emphasis is placed on comparative aspects of the egg-to-embryo transition across vertebrates and their evolution. The future prospects for work regarding self-organization and gene regulatory networks in the context of early axis formation are also discussed.
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Affiliation(s)
- Douglas W Houston
- Department of Biology, The University of Iowa, 257 BB, Iowa City, IA, 52242, USA.
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26
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King ML. Maternal messages to live by: a personal historical perspective. Genesis 2017; 55:10.1002/dvg.23007. [PMID: 28095642 PMCID: PMC5276792 DOI: 10.1002/dvg.23007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 11/22/2016] [Accepted: 11/24/2016] [Indexed: 12/17/2022]
Abstract
In the 1980s, the study of localized maternal mRNAs was just emerging as a new research area. Classic embryological studies had linked the inheritance of cytoplasmic domains with specific cell lineages, but the underlying molecular nature of these putative determinants remained a mystery. The model system Xenopus would play a pivotal role in the progress of this new field. In fact, the first localized maternal mRNA to be identified and cloned from any organism was Xenopus vg1, a TGF-beta family member. This seminal finding opened the door to many subsequent studies focused on how RNAs are localized and what functions they had in development. As the field moves into the future, Xenopus remains the system of choice for studies identifying RNA/protein transport particles and maternal RNAs through RNA-sequencing.
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Affiliation(s)
- Mary Lou King
- Department of Cell Biology, University of Miami Miller School of Medicine, 1011 NW 15th St, Miami, FL 33136, USA
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27
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Localization in Oogenesis of Maternal Regulators of Embryonic Development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 953:173-207. [DOI: 10.1007/978-3-319-46095-6_5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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28
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Welch E, Pelegri F. Cortical depth and differential transport of vegetally localized dorsal and germ line determinants in the zebrafish embryo. BIOARCHITECTURE 2016; 5:13-26. [PMID: 26528729 PMCID: PMC4832442 DOI: 10.1080/19490992.2015.1080891] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In zebrafish embryos, factors involved in both axis induction and primordial germ cell (PGC) development are localized to the vegetal pole of the egg. However, upon egg activation axis induction factors experience an asymmetric off-center shift whereas PGC factors undergo symmetric animally-directed movement. We examined the spatial relationship between the proposed dorsal genes wnt8a and grip2a and the PGC factor dazl at the vegetal cortex. We find that RNAs for these genes localize to different cortical depths, with the RNA for the PGC factor dazl at a deeper cortical level than those for axis-inducing factors. In addition, and in contrast to the role of microtubules in the long-range transport of dorsal determinants, we find that germ line determinant transport depends on the actin cytoskeleton. Our results support a model in which vegetal cortex differential RNA transport behavior is facilitated by RNA localization along cortical depth and differential coupling to cortical transport.
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Affiliation(s)
- Elaine Welch
- a Laboratory of Genetics; University of Wisconsin - Madison ; Madison , WI USA
| | - Francisco Pelegri
- a Laboratory of Genetics; University of Wisconsin - Madison ; Madison , WI USA
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29
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Fjelldal PG, Solberg MF, Hansen T, Vågseth T, Glover KA, Kryvi H. Salmonid fish: model organisms to study cardiovascular morphogenesis in conjoined twins? BMC DEVELOPMENTAL BIOLOGY 2016; 16:25. [PMID: 27422058 PMCID: PMC4947332 DOI: 10.1186/s12861-016-0125-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 07/08/2016] [Indexed: 11/13/2022]
Abstract
Background There is a gap in knowledge regarding the cardiovascular system in fish conjoined twins, and regarding the cardiovascular morphogenesis of conjoined twins in general. We examined the cardiovascular system in a pair of fully developed ventrally conjoined salmonid twins (45.5 g body weight), and the arrangement of the blood vessels during early development in ventrally conjoined yolk sac larvae salmonid twins (<0.5 g body weight). Results In the fully developed twins, one twin was normal, while the other was small and severely malformed. The mouth of the small twin was blocked, inhibiting respiration and feeding. Both twins had hearts, but these were connected through a common circulatory system. They were joined by the following blood vessels: (i) arteria iliaca running from arteria caudalis of the large twin to the kidney of the small twin; (ii) arteria subclavia running from aorta dorsalis of the large twin to aorta dorsalis of the small twin; (iii) vena hepatica running from the liver of the small twin into the sinus venosus of the large twin. Among the yolk sac larvae twins investigated, distinct vascular connections were found in some individuals through a joined v. vitellina hepatica. Conclusions Ventrally conjoined fish twins can develop cardiovascular connections during early development, enabling a normal superior twin to supply a malfunctioning twin with oxygen and nutrients. Since the yolk sac in salmonids is transparent, twinning in salmonids may be a useful model in which to study cardiovascular morphogenesis in conjoined twins. Electronic supplementary material The online version of this article (doi:10.1186/s12861-016-0125-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Per Gunnar Fjelldal
- Institute of Marine research (IMR), Matre Aquaculture Research Station, Matredal, Norway. .,Havforskningsinstituttet, Matre, Matre 5, 5984, Matredal, Norway.
| | | | - Tom Hansen
- Institute of Marine research (IMR), Matre Aquaculture Research Station, Matredal, Norway
| | - Tone Vågseth
- Institute of Marine research (IMR), Matre Aquaculture Research Station, Matredal, Norway
| | - Kevin Alan Glover
- Institute of Marine research (IMR), Bergen, Norway.,Department of Biology, University of Bergen, Bergen, Norway
| | - Harald Kryvi
- Department of Biology, University of Bergen, Bergen, Norway
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30
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Campbell PD, Heim AE, Smith MZ, Marlow FL. Kinesin-1 interacts with Bucky ball to form germ cells and is required to pattern the zebrafish body axis. Development 2015; 142:2996-3008. [PMID: 26253407 PMCID: PMC4582183 DOI: 10.1242/dev.124586] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/16/2015] [Indexed: 12/31/2022]
Abstract
In animals, specification of the primordial germ cells (PGCs), the stem cells of the germ line, is required to transmit genetic information from one generation to the next. Bucky ball (Buc) is essential for germ plasm (GP) assembly in oocytes, and its overexpression results in excess PGCs in zebrafish embryos. However, the mechanistic basis for the excess PGCs in response to Buc overexpression, and whether endogenous Buc functions during embryogenesis, are unknown. Here, we show that endogenous Buc, like GP and overexpressed Buc-GFP, accumulates at embryonic cleavage furrows. Furthermore, we show that the maternally expressed zebrafish Kinesin-1 Kif5Ba is a binding partner of Buc and that maternal kif5Ba (Mkif5Ba) plays an essential role in germline specification in vivo. Specifically, Mkif5Ba is required to recruit GP to cleavage furrows and thereby specifies PGCs. Moreover, Mkif5Ba is required to enrich Buc at cleavage furrows and for the ability of Buc to promote excess PGCs, providing mechanistic insight into how Buc functions to assemble embryonic GP. In addition, we show that Mkif5Ba is also essential for dorsoventral (DV) patterning. Specifically, Mkif5Ba promotes formation of the parallel vegetal microtubule array required to asymmetrically position dorsal determinants (DDs) towards the prospective dorsal side. Interestingly, whereas Syntabulin and wnt8a translocation depend on kif5Ba, grip2a translocation does not, providing evidence for two distinct mechanisms by which DDs might be asymmetrically distributed. These studies identify essential roles for maternal Kif5Ba in PGC specification and DV patterning, and provide mechanistic insight into Buc functions during early embryogenesis.
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Affiliation(s)
- Philip D Campbell
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA
| | - Amanda E Heim
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA
| | - Mordechai Z Smith
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA
| | - Florence L Marlow
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA Department of Neuroscience, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA
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31
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Yang J, Aguero T, King ML. The Xenopus Maternal-to-Zygotic Transition from the Perspective of the Germline. Curr Top Dev Biol 2015; 113:271-303. [PMID: 26358876 DOI: 10.1016/bs.ctdb.2015.07.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In Xenopus, the germline is specified by the inheritance of germ-plasm components synthesized at the beginning of oogenesis. Only the cells in the early embryo that receive germ plasm, the primordial germ cells (PGCs), are competent to give rise to the gametes. Thus, germ-plasm components continue the totipotent potential exhibited by the oocyte into the developing embryo at a time when most cells are preprogrammed for somatic differentiation as dictated by localized maternal determinants. When zygotic transcription begins at the mid-blastula transition, the maternally set program for somatic differentiation is realized. At this time, genetic control is ceded to the zygotic genome, and developmental potential gradually becomes more restricted within the primary germ layers. PGCs are a notable exception to this paradigm and remain transcriptionally silent until the late gastrula. How the germ-cell lineage retains full potential while somatic cells become fate restricted is a tale of translational repression, selective degradation of somatic maternal determinants, and delayed activation of zygotic transcription.
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Affiliation(s)
- Jing Yang
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Tristan Aguero
- Department of Cell Biology, University of Miami, Miller School of Medicine, Miami, Florida, USA
| | - Mary Lou King
- Department of Cell Biology, University of Miami, Miller School of Medicine, Miami, Florida, USA.
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32
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Li-Villarreal N, Forbes MM, Loza AJ, Chen J, Ma T, Helde K, Moens CB, Shin J, Sawada A, Hindes AE, Dubrulle J, Schier AF, Longmore GD, Marlow FL, Solnica-Krezel L. Dachsous1b cadherin regulates actin and microtubule cytoskeleton during early zebrafish embryogenesis. Development 2015; 142:2704-18. [PMID: 26160902 DOI: 10.1242/dev.119800] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 06/25/2015] [Indexed: 01/04/2023]
Abstract
Dachsous (Dchs), an atypical cadherin, is an evolutionarily conserved regulator of planar cell polarity, tissue size and cell adhesion. In humans, DCHS1 mutations cause pleiotropic Van Maldergem syndrome. Here, we report that mutations in zebrafish dchs1b and dchs2 disrupt several aspects of embryogenesis, including gastrulation. Unexpectedly, maternal zygotic (MZ) dchs1b mutants show defects in the earliest developmental stage, egg activation, including abnormal cortical granule exocytosis (CGE), cytoplasmic segregation, cleavages and maternal mRNA translocation, in transcriptionally quiescent embryos. Later, MZdchs1b mutants exhibit altered dorsal organizer and mesendodermal gene expression, due to impaired dorsal determinant transport and Nodal signaling. Mechanistically, MZdchs1b phenotypes can be explained in part by defective actin or microtubule networks, which appear bundled in mutants. Accordingly, disruption of actin cytoskeleton in wild-type embryos phenocopied MZdchs1b mutant defects in cytoplasmic segregation and CGE, whereas interfering with microtubules in wild-type embryos impaired dorsal organizer and mesodermal gene expression without perceptible earlier phenotypes. Moreover, the bundled microtubule phenotype was partially rescued by expressing either full-length Dchs1b or its intracellular domain, suggesting that Dchs1b affects microtubules and some developmental processes independent of its known ligand Fat. Our results indicate novel roles for vertebrate Dchs in actin and microtubule cytoskeleton regulation in the unanticipated context of the single-celled embryo.
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Affiliation(s)
- Nanbing Li-Villarreal
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Meredyth M Forbes
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA
| | - Andrew J Loza
- Department of Internal Medicine, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Jiakun Chen
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Taylur Ma
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Kathryn Helde
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Cecilia B Moens
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Jimann Shin
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Atsushi Sawada
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Anna E Hindes
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Julien Dubrulle
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Alexander F Schier
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Gregory D Longmore
- Department of Internal Medicine, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Florence L Marlow
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA Department of Neuroscience, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA
| | - Lilianna Solnica-Krezel
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
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33
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Olson DJ, Oh D, Houston DW. The dynamics of plus end polarization and microtubule assembly during Xenopus cortical rotation. Dev Biol 2015; 401:249-63. [PMID: 25753733 PMCID: PMC4424176 DOI: 10.1016/j.ydbio.2015.01.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Revised: 01/23/2015] [Accepted: 01/28/2015] [Indexed: 11/26/2022]
Abstract
The self-organization of dorsally-directed microtubules during cortical rotation in the Xenopus egg is essential for dorsal axis formation. The mechanisms controlling this process have been problematic to analyze, owing to difficulties in visualizing microtubules in living egg. Also, the order of events occurring at the onset of cortical rotation have not been satisfactorily visualized in vivo and have been inferred from staged fixed samples. To address these issues, we have characterized the dynamics of total microtubule and plus end behavior continuously throughout cortical rotation, as well as in oocytes and unfertilized eggs. Here, we show that the nascent microtubule network forms in the cortex but associates with the deep cytoplasm at the start of rotation. Importantly, plus ends remain cortical and become increasingly more numerous and active prior to rotation, with dorsal polarization occurring rapidly after the onset of rotation. Additionally, we show that vegetally localized Trim36 is required to attenuate dynamic plus end growth, suggesting that vegetal factors are needed to locally coordinate growth in the cortex.
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Affiliation(s)
- David J Olson
- The University of Iowa, Department of Biology, 257 BB, Iowa City, IA 52242-1324, USA
| | - Denise Oh
- The University of Iowa, Department of Biology, 257 BB, Iowa City, IA 52242-1324, USA
| | - Douglas W Houston
- The University of Iowa, Department of Biology, 257 BB, Iowa City, IA 52242-1324, USA.
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34
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Dosch R. Next generation mothers: Maternal control of germline development in zebrafish. Crit Rev Biochem Mol Biol 2014; 50:54-68. [DOI: 10.3109/10409238.2014.985816] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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