1
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Fuentes R, Marlow FL, Abrams EW, Zhang H, Kobayashi M, Gupta T, Kapp LD, DiNardo Z, Heller R, Cisternas R, García-Castro P, Segovia-Miranda F, Montecinos-Franjola F, Vought W, Vejnar CE, Giraldez AJ, Mullins MC. Maternal regulation of the vertebrate oocyte-to-embryo transition. PLoS Genet 2024; 20:e1011343. [PMID: 39052672 DOI: 10.1371/journal.pgen.1011343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 08/06/2024] [Accepted: 06/13/2024] [Indexed: 07/27/2024] Open
Abstract
Maternally-loaded factors in the egg accumulate during oogenesis and are essential for the acquisition of oocyte and egg developmental competence to ensure the production of viable embryos. However, their molecular nature and functional importance remain poorly understood. Here, we present a collection of 9 recessive maternal-effect mutants identified in a zebrafish forward genetic screen that reveal unique molecular insights into the mechanisms controlling the vertebrate oocyte-to-embryo transition. Four genes, over easy, p33bjta, poached and black caviar, were found to control initial steps in yolk globule sizing and protein cleavage during oocyte maturation that act independently of nuclear maturation. The krang, kazukuram, p28tabj, and spotty genes play distinct roles in egg activation, including cortical granule biology, cytoplasmic segregation, the regulation of microtubule organizing center assembly and microtubule nucleation, and establishing the basic body plan. Furthermore, we cloned two of the mutant genes, identifying the over easy gene as a subunit of the Adaptor Protein complex 5, Ap5m1, which implicates it in regulating intracellular trafficking and yolk vesicle formation. The novel maternal protein Krang/Kiaa0513, highly conserved in metazoans, was discovered and linked to the function of cortical granules during egg activation. These mutant genes represent novel genetic entry points to decipher the molecular mechanisms functioning in the oocyte-to-embryo transition, fertility, and human disease. Additionally, our genetic adult screen not only contributes to the existing knowledge in the field but also sets the basis for future investigations. Thus, the identified maternal genes represent key players in the coordination and execution of events prior to fertilization.
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Affiliation(s)
- Ricardo Fuentes
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Florence L Marlow
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine Mount Sinai, New York, New York, United States of America
| | - 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, State University of New York, Purchase, New York, 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
| | - Manami Kobayashi
- 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
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lee D Kapp
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Zachary DiNardo
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Ronald Heller
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Ruth Cisternas
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Priscila García-Castro
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Fabián Segovia-Miranda
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Felipe Montecinos-Franjola
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health, Bethesda, Maryland, United States of America
| | - William Vought
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Charles E Vejnar
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Antonio J Giraldez
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, 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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2
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Ren F, Lin Q, Gong G, Du X, Dan H, Qin W, Miao R, Xiong Y, Xiao R, Li X, Gui JF, Mei J. Igf2bp3 maintains maternal RNA stability and ensures early embryo development in zebrafish. Commun Biol 2020; 3:94. [PMID: 32127635 PMCID: PMC7054421 DOI: 10.1038/s42003-020-0827-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 02/11/2020] [Indexed: 12/22/2022] Open
Abstract
Early embryogenesis relies on maternally inherited mRNAs. Although the mechanism of maternal mRNA degradation during maternal-to-zygotic transition (MZT) has been extensively studied in vertebrates, how the embryos maintain maternal mRNA stability remains unclear. Here, we identify Igf2bp3 as an important regulator of maternal mRNA stability in zebrafish. Depletion of maternal igf2bp3 destabilizes maternal mRNAs prior to MZT and leads to severe developmental defects, including abnormal cytoskeleton organization and cell division. However, the process of oogenesis and the expression levels of maternal mRNAs in unfertilized eggs are normal in maternal igf2bp3 mutants. Gene ontology analysis revealed that these functions are largely mediated by Igf2bp3-bound mRNAs. Indeed, Igf2bp3 depletion destabilizes while its overexpression enhances its targeting maternal mRNAs. Interestingly, igf2bp3 overexpression in wild-type embryos also causes a developmental delay. Altogether, these findings highlight an important function of Igf2bp3 in controlling early zebrafish embryogenesis by binding and regulating the stability of maternal mRNAs.
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Affiliation(s)
- Fan Ren
- College of Fisheries, Huazhong Agricultural University, 430070, Wuhan, China
| | - Qiaohong Lin
- College of Fisheries, Huazhong Agricultural University, 430070, Wuhan, China
| | - Gaorui Gong
- College of Fisheries, Huazhong Agricultural University, 430070, Wuhan, China
| | - Xian Du
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, and Department of Hematology, Zhongnan Hospital of Wuhan University, Wuhan University, 430071, Wuhan, China
| | - Hong Dan
- College of Fisheries, Huazhong Agricultural University, 430070, Wuhan, China
| | - Wenying Qin
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, and Department of Hematology, Zhongnan Hospital of Wuhan University, Wuhan University, 430071, Wuhan, China
| | - Ran Miao
- College of Fisheries, Huazhong Agricultural University, 430070, Wuhan, China
| | - Yang Xiong
- College of Fisheries, Huazhong Agricultural University, 430070, Wuhan, China
| | - Rui Xiao
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, and Department of Hematology, Zhongnan Hospital of Wuhan University, Wuhan University, 430071, Wuhan, China
| | - Xiaohui Li
- College of Fisheries, Huazhong Agricultural University, 430070, Wuhan, China
| | - Jian-Fang Gui
- College of Fisheries, Huazhong Agricultural University, 430070, Wuhan, China
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, 430072, Wuhan, China
| | - Jie Mei
- College of Fisheries, Huazhong Agricultural University, 430070, Wuhan, China.
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3
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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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Eno C, Solanki B, Pelegri F. aura (mid1ip1l) regulates the cytoskeleton at the zebrafish egg-to-embryo transition. Development 2016; 143:1585-99. [PMID: 26965374 PMCID: PMC4986165 DOI: 10.1242/dev.130591] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 03/01/2016] [Indexed: 12/11/2022]
Abstract
Embryos from females homozygous for a recessive maternal-effect mutation in the gene aura exhibit defects including reduced cortical integrity, defective cortical granule (CG) release upon egg activation, failure to complete cytokinesis, and abnormal cell wound healing. We show that the cytokinesis defects are associated with aberrant cytoskeletal reorganization during furrow maturation, including abnormal F-actin enrichment and microtubule reorganization. Cortical F-actin prior to furrow formation fails to exhibit a normal transition into F-actin-rich arcs, and drug inhibition is consistent with aura function promoting F-actin polymerization and/or stabilization. In mutants, components of exocytic and endocytic vesicles, such as Vamp2, Clathrin and Dynamin, are sequestered in unreleased CGs, indicating a need for CG recycling in the normal redistribution of these factors. However, the exocytic targeting factor Rab11 is recruited to the furrow plane normally at the tip of bundling microtubules, suggesting an alternative anchoring mechanism independent of membrane recycling. A positional cloning approach indicates that the mutation in aura is associated with a truncation of Mid1 interacting protein 1 like (Mid1ip1l), previously identified as an interactor of the X-linked Opitz G/BBB syndrome gene product Mid1. A Cas9/CRISPR-induced mutant allele in mid1ip1l fails to complement the originally isolated aura maternal-effect mutation, confirming gene assignment. Mid1ip1l protein localizes to cortical F-actin aggregates, consistent with a direct role in cytoskeletal regulation. Our studies indicate that maternally provided aura (mid1ip1l) acts during the reorganization of the cytoskeleton at the egg-to-embryo transition and highlight the importance of cytoskeletal dynamics and membrane recycling during this developmental period.
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Affiliation(s)
- Celeste Eno
- Laboratory of Genetics, University of Wisconsin - Madison, 425-G Henry Mall, Room 2455 Genetics, Madison, WI 53706, USA
| | - Bharti Solanki
- Laboratory of Genetics, University of Wisconsin - Madison, 425-G Henry Mall, Room 2455 Genetics, Madison, WI 53706, USA
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin - Madison, 425-G Henry Mall, Room 2455 Genetics, Madison, WI 53706, USA
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5
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Turnover of the actomyosin complex in zebrafish embryos directs geometric remodelling and the recruitment of lipid droplets. Sci Rep 2015; 5:13915. [PMID: 26355567 PMCID: PMC4650301 DOI: 10.1038/srep13915] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 08/10/2015] [Indexed: 11/19/2022] Open
Abstract
Lipid droplets (LDs), reservoirs of cholesterols and fats, are organelles that
hydrolyse lipids in the cell. In zebrafish embryos, the actomyosin complex and
filamentous microtubules control the periodic regulation of the LD geometry.
Contrary to the existing hypothesis that LD transport involves the
kinesin-microtubule system, we find that their recruitment to the blastodisc depends
on the actomyosin turnover and is independent of the microtubules. For the first
time we report the existence of two distinct states of LDs, an inactive and an
active state, that occur periodically, coupled weakly to the cleavage cycles. LDs
are bigger, more circular and more stable in the inactive state in which the
geometry of the LDs is maintained by actomyosin as well as microtubules. The active
state has smaller and irregularly shaped LDs that show shape fluctuations that are
linked to actin depolymerization. Because most functions of LDs employ surface
interactions, our findings on the LD geometry and its regulation bring new insights
to the mechanisms associated with specific functions of LDs, such as their storage
capacity for fats or proteins, lipolysis etc.
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6
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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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7
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Nair S, Lindeman RE, Pelegri F. In vitro oocyte culture-based manipulation of zebrafish maternal genes. Dev Dyn 2012; 242:44-52. [PMID: 23074011 DOI: 10.1002/dvdy.23894] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2012] [Indexed: 12/12/2022] Open
Abstract
In animals, females deposit gene products into developing oocytes, which drive early cellular events in embryos immediately after fertilization. As maternal gene products are present before fertilization, the functional manipulation of maternal genes is often challenging to implement, requiring gene expression or targeting during oogenesis. Maternal expression can be achieved through transgenesis, but transgenic approaches are time consuming and subject to undesired epigenetic effects. Here, we have implemented in vitro culturing of experimentally manipulated immature oocytes to study maternal gene contribution to early embryonic development in the zebrafish. We demonstrate phenotypic rescue of a maternal-effect mutation by expressing wild-type product in cultured oocytes. We also generate loss-of-function phenotypes in embryos through either the expression of a dominant-negative transcript or injection of translation-blocking morpholino oligonucleotides. Finally, we demonstrate subcellular localization during the early cell divisions immediately after fertilization of an exogenously provided maternal product fused to a fluorescent protein. These manipulations extend the potential to carry out genetic and imaging studies of zebrafish maternal genes during the egg-to-embryo transition.
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Affiliation(s)
- Sreelaja Nair
- Laboratory of Genetics, University of Wisconsin - Madison, Madison, WI, USA
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8
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Arantes FP, Santos HB, Rizzo E, Sato Y, Bazzoli N. Influence of water temperature on induced reproduction by hypophysation, sex steroids concentrations and final oocyte maturation of the "curimatã-pacu" Prochilodus argenteus (Pisces: Prochilodontidae). Gen Comp Endocrinol 2011; 172:400-8. [PMID: 21501616 DOI: 10.1016/j.ygcen.2011.04.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 03/18/2011] [Accepted: 04/04/2011] [Indexed: 11/27/2022]
Abstract
Most fishes with commercial importance from the São Francisco basin are migratory and do not complete the reproductive cycle in lentic environments, such as hydroelectric plant reservoirs, hence natural stocks are declining and there is an urgent need to reduce the pressure of fishing on those wild populations. Therefore, studies on reproductive biology and its relationship with endocrine and environmental factors are key to improving the cultivation techniques of Brazilian fish species. This study examined the influence of water temperature on sex steroid concentrations (testosterone, 17β-estradiol and 17α-hydroxyprogesterone), spawning efficiency, fecundity, fertilisation rate, larval abnormality rates and involvement of the cytoskeleton during the final oocyte maturation of Prochilodus argenteus under experimental conditions. The results of our study showed that in captivity, sex steroid plasma concentrations and spawning performance of P. argenteus were clearly different for fish kept in water with different temperature regimes. In lower water temperature (23°C), it was observed that: 33% of females did not ovulate, fecundity was lower and vitellogenic oocytes after the spawning induction procedure exhibited a smaller diameter. Moreover, concentrations of 17β-estradiol and 17α-hydroxyprogesterone were lower and there was a delay in the final oocyte maturation and, consequently, ovulation and spawning. Our experiments showed direct influence of water temperature in the process of induced spawning of P. argenteus. Changes in water temperature also suggest the tubulin involvement in the nuclear dislocation process and the possible action of actin filaments in the release of polar bodies during final oocyte maturation of P. argenteus.
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Affiliation(s)
- Fábio P Arantes
- Departamento de Morfologia Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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9
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Ptenb mediates gastrulation cell movements via Cdc42/AKT1 in zebrafish. PLoS One 2011; 6:e18702. [PMID: 21494560 PMCID: PMC3073981 DOI: 10.1371/journal.pone.0018702] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 03/15/2011] [Indexed: 01/12/2023] Open
Abstract
Phosphatidylinositol 3-kinase (PI3 kinase) mediates gastrulation cell migration in zebrafish via its regulation of PIP2/PIP3 balance. Although PI3 kinase counter enzyme PTEN has also been reported to be essential for gastrulation, its role in zebrafish gastrulation has been controversial due to the lack of gastrulation defects in pten-null mutants. To clarify this issue, we knocked down a pten isoform, ptenb by using anti-sense morpholino oligos (MOs) in zebrafish embryos and found that ptenb MOs inhibit convergent extension by affecting cell motility and protrusion during gastrulation. The ptenb MO-induced convergence defect could be rescued by a PI3-kinase inhibitor, LY294002 and by overexpressing dominant negative Cdc42. Overexpression of human constitutively active akt1 showed similar convergent extension defects in zebrafish embryos. We also observed a clear enhancement of actin polymerization in ptenb morphants under cofocal microscopy and in actin polymerization assay. These results suggest that Ptenb by antagonizing PI3 kinase and its downstream Akt1 and Cdc42 to regulate actin polymerization that is critical for proper cell motility and migration control during gastrulation in zebrafish.
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10
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Gupta T, Marlow FL, Ferriola D, Mackiewicz K, Dapprich J, Monos D, Mullins MC. Microtubule actin crosslinking factor 1 regulates the Balbiani body and animal-vegetal polarity of the zebrafish oocyte. PLoS Genet 2010; 6:e1001073. [PMID: 20808893 PMCID: PMC2924321 DOI: 10.1371/journal.pgen.1001073] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Accepted: 07/15/2010] [Indexed: 11/23/2022] Open
Abstract
Although of fundamental importance in developmental biology, the genetic basis for the symmetry breaking events that polarize the vertebrate oocyte and egg are largely unknown. In vertebrates, the first morphological asymmetry in the oocyte is the Balbiani body, a highly conserved, transient structure found in vertebrates and invertebrates including Drosophila, Xenopus, human, and mouse. We report the identification of the zebrafish magellan (mgn) mutant, which exhibits a novel enlarged Balbiani body phenotype and a disruption of oocyte polarity. To determine the molecular identity of the mgn gene, we positionally cloned the gene, employing a novel DNA capture method to target region-specific genomic DNA of 600 kb for massively parallel sequencing. Using this technique, we were able to enrich for the genomic region linked to our mutation within one week and then identify the mutation in mgn using massively parallel sequencing. This is one of the first successful uses of genomic DNA enrichment combined with massively parallel sequencing to determine the molecular identity of a gene associated with a mutant phenotype. We anticipate that the combination of these technologies will have wide applicability for the efficient identification of mutant genes in all organisms. We identified the mutation in mgn as a deletion in the coding sequence of the zebrafish microtubule actin crosslinking factor 1 (macf1) gene. macf1 is a member of the highly conserved spectraplakin family of cytoskeletal linker proteins, which play diverse roles in polarized cells such as neurons, muscle cells, and epithelial cells. In mgn mutants, the oocyte nucleus is mislocalized; and the Balbiani body, localized mRNAs, and organelles are absent from the periphery of the oocyte, consistent with a function for macf1 in nuclear anchoring and cortical localization. These data provide the first evidence for a role for spectraplakins in polarization of the vertebrate oocyte and egg. How the axes of the embryo are established is an important question in developmental biology. In many organisms, the axes of the embryo are established during oogenesis through the generation of a polarized egg. Very little is known regarding the mechanisms of polarity establishment and maintenance in vertebrate oocytes and eggs. We have identified a zebrafish mutant called magellan, which displays a defect in egg polarity. The gene disrupted in the magellan mutant encodes the cytoskeletal linker protein microtubule actin crosslinking factor 1 (macf1). In vertebrates, it can take years to identify the molecular nature of a mutation. We used a new technique to identify the magellan mutation, which allowed us to rapidly isolate genomic DNA linked to the mutation and sequence it. Our results describe an important new function for macf1 in polarizing the oocyte and egg and demonstrate the feasibility of this new technique for the efficient identification of mutations.
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Affiliation(s)
- Tripti Gupta
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Florence L. Marlow
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Deborah Ferriola
- Generation Biotech, Lawrenceville, New Jersey, United States of America
- Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Katarzyna Mackiewicz
- Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Johannes Dapprich
- Generation Biotech, Lawrenceville, New Jersey, United States of America
| | - Dimitri Monos
- Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Mary C. Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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11
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Fuentes R, Fernández J. Ooplasmic segregation in the zebrafish zygote and early embryo: Pattern of ooplasmic movements and transport pathways. Dev Dyn 2010; 239:2172-89. [DOI: 10.1002/dvdy.22349] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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12
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Lindeman RE, Pelegri F. Vertebrate maternal-effect genes: Insights into fertilization, early cleavage divisions, and germ cell determinant localization from studies in the zebrafish. Mol Reprod Dev 2010; 77:299-313. [PMID: 19908256 PMCID: PMC4276564 DOI: 10.1002/mrd.21128] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In the earliest stages of animal development prior to the commencement of zygotic transcription, all critical cellular processes are carried out by maternally-provided molecular products accumulated in the egg during oogenesis. Disruption of these maternal products can lead to defective embryogenesis. In this review, we focus on maternal genes with roles in the fundamental processes of fertilization, cell division, centrosome regulation, and germ cell development with emphasis on findings from the zebrafish, as this is a unique and valuable model system for vertebrate reproduction.
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Affiliation(s)
- Robin E. Lindeman
- Laboratory of Genetics, University of Wisconsin – Madison, Madison, Wisconsin
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin – Madison, Madison, Wisconsin
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13
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Mei W, Lee KW, Marlow FL, Miller AL, Mullins MC. hnRNP I is required to generate the Ca2+ signal that causes egg activation in zebrafish. Development 2009; 136:3007-17. [PMID: 19666827 DOI: 10.1242/dev.037879] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Egg activation is an important cellular event required to prevent polyspermy and initiate development of the zygote. Egg activation in all animals examined is elicited by a rise in free Ca(2+) in the egg cytosol at fertilization. This Ca(2+) rise is crucial for all subsequent egg activation steps, such as cortical granule exocytosis, which modifies the vitelline membrane to prevent polyspermy. The cytosolic Ca(2+) rise is primarily initiated by inositol 1,4,5-trisphosphate (IP(3))-mediated Ca(2+) release from the endoplasmic reticulum. The genes involved in regulating the IP(3)-mediated Ca(2+) release during egg activation remain largely unknown. Here we report on a zebrafish maternal-effect mutant, brom bones, which is defective in the cytosolic Ca(2+) rise and subsequent egg activation events, including cortical granule exocytosis and cytoplasmic segregation. We show that the egg activation defects in brom bones can be rescued by providing Ca(2+) or the Ca(2+)-release messenger IP(3), suggesting that brom bones is a regulator of IP(3)-mediated Ca(2+) release at fertilization. Interestingly, brom bones mutant embryos also display defects in dorsoventral axis formation accompanied by a disorganized cortical microtubule network, which is known to be crucial for dorsal axis formation. We provide evidence that the impaired microtubule organization is associated with non-exocytosed cortical granules from the earlier egg activation defect. Positional cloning of the brom bones gene reveals that a premature stop codon in the gene encoding hnRNP I (referred to here as hnrnp I) underlies the abnormalities. Our studies therefore reveal an important new role of hnrnp I in regulating the fundamental process of IP(3)-mediated Ca(2+) release at egg activation.
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Affiliation(s)
- Wenyan Mei
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, 421 Curie Boulevard, Philadelphia, PA 19104, USA
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Youhua Tan, Dong Sun, Wenhao Huang, Shuk Han Cheng. Mechanical Modeling of Biological Cells in Microinjection. IEEE Trans Nanobioscience 2008; 7:257-66. [DOI: 10.1109/tnb.2008.2011852] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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DePina AS, Wöllert T, Langford GM. Membrane associated nonmuscle myosin II functions as a motor for actin-based vesicle transport in clam oocyte extracts. ACTA ACUST UNITED AC 2007; 64:739-55. [PMID: 17630664 DOI: 10.1002/cm.20219] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Nonmuscle myosin II (Myo2) has been shown to associate with membranes of the trans-Golgi network and to be involved in Golgi to ER retrograde protein transport. Here, we provide evidence that Myo2 not only associates with membranes but functions to transport vesicles on actin filaments (AFs). We used extracts from unactivated clam oocytes for these studies. AFs assembled spontaneously in these extracts and myosin-dependent vesicle transport was observed upon activation. In addition, actin bundles formed and moved relative to each other at an average speed of 0.30 microm/s. Motion analysis revealed that vesicles moved on the spontaneously assembled AFs at speeds greater than 1 microm/s. The motor on these vesicles was identified as a member of the nonmuscle Myo2 family based on sequence determination by Edman chemistry. Vesicles in these extracts were purified by sucrose gradient centrifugation and movement was reconstituted in vitro using skeletal muscle actin coated coverslips. When peripheral membrane proteins of vesicles including Myo2 were removed by salt stripping or when extracts were treated with an antibody specific to clam oocyte nonmuscle Myo2, vesicle movement was inhibited. Blebbistatin, a Myo2 specific inhibitor, also blocked vesicle movement. Myo2 light chain kinase activity was found to be essential for vesicle movement and sliding of actin bundles. Together, our data provide direct evidence that nonmuscle Myo2 is involved in actin-dependent vesicle transport in clam oocytes.
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Affiliation(s)
- Ana S DePina
- Marine Biological Laboratory, Woods Hole, Massachusetts, USA
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Eliyahu E, Tsaadon A, Shtraizent N, Shalgi R. The involvement of protein kinase C and actin filaments in cortical granule exocytosis in the rat. Reproduction 2005; 129:161-70. [PMID: 15695610 DOI: 10.1530/rep.1.00424] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mammalian sperm–egg fusion results in cortical granule exocytosis (CGE) and resumption of meiosis. Studies of various exocytotic cells suggest that filamentous actin (F-actin) blocks exocytosis by excluding secretory vesicles from the plasma membrane. However, the exact function of these microfilaments, in mammalian egg CGE, is still elusive. In the present study we investigated the role of actin in the process of CGE, and the possible interaction between actin and protein kinase C (PKC), by using coimmunoprecipitation, immunohistochemistry and confocal microscopy. We identified an interaction between actin and the PKC alpha isoenzyme in non-activated metaphase II (MII) eggs and in eggs activated by phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA). F-actin was evenly distributed throughout the egg’s cytosol with a marked concentration at the cortex and at the plasma membrane. A decrease in the fluorescence signal of F-actin, which represents its depolymerization/reorganization, was detected upon fertilization and upon parthenogenetic activation. Exposing the eggs to drugs that cause either polymerization or depolymerization of actin (jasplakinolide (JAS) and cytochalasin D (CD) respectively) did not induce or prevent CGE. However, CD, but not JAS, followed by a low dose of TPA doubled the percentage of eggs undergoing complete CGE, as compared with TPA alone. We further demonstrated that myristoylated alanin-rich C kinase substrate (MARCKS), a protein known to cross-link F-actin in other cell types, is expressed in rat eggs and is colocalized with actin. In view of our results, we suggest that the cytoskeletal cortex is not a mere physical barrier that blocks CGE, but rather a dynamic network that can be maneuvered towards allowing CGE by activated actin-associated proteins and/or by activated PKC.
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Affiliation(s)
- E Eliyahu
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
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17
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Abstract
All processes that occur before the activation of the zygotic genome at the midblastula transition are driven by maternal products, which are produced during oogenesis and stored in the mature oocyte. Upon egg activation and fertilization, these maternal factors initiate developmental cascades that carry out the embryonic developmental program. Even after the initiation of zygotic gene expression, perduring maternal products continue performing essential functions, either together with other maternal factors or through interactions with newly expressed zygotic products. Advances in zebrafish research have placed this organism in a unique position to contribute to a detailed understanding of the role of maternal factors in early vertebrate development. This review summarizes our knowledge on the processes involved in the production and redistribution of maternal factors during zebrafish oogenesis and early development, as well as our understanding of the function of these factors in axis formation, germ layer and germ cell specification, and other early embryonic processes.
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Affiliation(s)
- Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, USA.
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Rizzo E, Godinho HP, Sato Y. Short-term storage of oocytes from the neotropical teleost fish Prochilodus marggravii. Theriogenology 2003; 60:1059-70. [PMID: 12935846 DOI: 10.1016/s0093-691x(03)00108-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The loss of oocyte viability after ovulation is one of the limiting factors in controlled reproduction of several fish species. Experiments were performed with 15 feral Prochilodus marggravii female fish induced to spawn with crude carp pituitary extract to evaluate the viability of oocytes retained within the ovarian cavity (in situ storage) and outside of the ovarian cavity (ex situ storage). Because fertility rates rapidly declined after ovulation, simultaneously with an increase in the number of deformed larvae, P. marggravii oocytes could only be successfully stored for 1 h ex situ at room temperature ( approximately 26 degrees C). There was a highly negative correlation (r = -0.82) between fertilization and deformed larvae during in situ storage at approximately 26 degrees C. Ex situ cooling (18 degrees C) caused a drastic reduction in fertilization rates as compared with storage at approximately 26 degrees C. Oocyte structure was preserved during 2 h storage and the cortical reaction was induced before spawning. Since the micropylar apparatus remained open, it was not the primary cause for the loss of oocyte fertility. The cytoskeleton of the oocyte appeared to be affected since ooplasmic segregation was altered after 2 h storage.
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Affiliation(s)
- Elizete Rizzo
- Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, P.O. Box 486, 30161-970 Belo Horizonte, MG, Brazil.
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Affiliation(s)
- J Topczewski
- Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235, USA
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Becker KA, Hart NH. Reorganization of filamentous actin and myosin-II in zebrafish eggs correlates temporally and spatially with cortical granule exocytosis. J Cell Sci 1999; 112 ( Pt 1):97-110. [PMID: 9841907 DOI: 10.1242/jcs.112.1.97] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The zebrafish egg provides a useful experimental system to study events of fertilization, including exocytosis. We show by differential interference contrast videomicroscopy that cortical granules are: (1) released nonsynchronously over the egg surface and (2) mobilized to the plasma membrane in two phases, depending upon vesicle size and location. Turbidometric assay measurements of the timing and extent of exocytosis revealed a steady release of small granules during the first 30 seconds of egg activation. This was followed by an explosive discharge of large granules, beginning at 30 seconds and continuing for 1–2 minutes. Stages of single granule exocytosis and subsequent remodeling of the egg surface were imaged by either real-time or time-lapse videomicroscopy as well as scanning electron microscopy. Cortical granule translocation and fusion with the plasma membrane were followed by the concurrent expansion of a fusion pore and release of granule contents. A dramatic rearrangement of the egg surface followed exocytosis. Cortical crypts (sites of evacuated granules) displayed a purse-string-like contraction, resulting in their gradual flattening and disappearance from the egg surface. We tested the hypothesis that subplasmalemmal filamentous (F-) actin acts as a physical barrier to secretion and is locally disassembled prior to granule release. Experimental results showed a reduction of rhodamine-phalloidin and antimyosin staining at putative sites of secretion, acceleration of the timing and extent of granule release in eggs pretreated with cytochalasin D, and dose-dependent inhibition of exocytosis in permeabilized eggs preincubated with phalloidin. An increase in assembled actin was detected by fluorometric assay during the period of exocytosis. Localization studies showed that F-actin and myosin-II codistributed with an inward-moving, membrane-delimited zone of cytoplasm that circumscribed cortical crypts during their transformation. Furthermore, cortical crypts displayed a distinct delay in transformation when incubated continuously with cytochalasin D following egg activation. We propose that closure of cortical crypts is driven by a contractile ring whose forces depend upon dynamic actin filaments and perhaps actomyosin interactions.
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Affiliation(s)
- K A Becker
- Rutgers University, Department of Cell Biology and Neuroscience, Busch Campus, Nelson Biology Laboratories, Piscataway, NJ 08854-8082, USA
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Hart NH, Fluck RA. Cytoskeleton in teleost eggs and early embryos: contributions to cytoarchitecture and motile events. Curr Top Dev Biol 1996; 31:343-81. [PMID: 8746670 DOI: 10.1016/s0070-2153(08)60233-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- N H Hart
- Department of Biological Sciences, Rutgers University, Piscataway, New Jersey 08855, USA
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