Reorganization of cytoplasm in the zebrafish oocyte and egg during early steps of ooplasmic segregation

Fernández, Juan; Valladares, Macarena; Fuentes, Ricardo; Ubilla, Andrea

doi:10.1002/dvdy.20682

Cited by 37 publications

(41 citation statements)

References 38 publications

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“…Cortical granules (CG) release their contents at the egg cortex, contributing to chorion expansion and surface remodeling (Fuentes and Fernandez, 2010;Hart, 1990;Tsaadon et al, 2006;Wong and Wessel, 2006). Stabilizing or destabilizing F-actin established the dependence of both CGE and cytoplasmic streaming on a dynamic actin cytoskeleton (Becker and Hart, 1999;Fernandez et al, 2006;Hart and Fluck, 1996;Ivanenkov et al, 1987;Leung et al, 2000;Wolenski and Hart, 1988). Maternally deposited dorsal determinants (DDs), including wnt8a mRNA, reside at the vegetal pole (Kosaka et al, 2007;Lu et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Dachsous1b cadherin regulates actin and microtubule cytoskeleton during early zebrafish embryogenesis

et al. 2015

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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 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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Section: Introductionmentioning

confidence: 99%

Dachsous1b cadherin regulates actin and microtubule cytoskeleton during early zebrafish embryogenesis

et al. 2015

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“…Egg activation in zebrafish is marked by elevation of the chorion and by segregation of the cytoplasm, which is initially integrated within the yolk, to the animal pole to form the single-cell blastodisc (Fernandez et al, 2006;Hart and Fluck, 1995). Chorion elevation is a consequence of CGE and is completed within minutes of egg activation (Becker and Hart, 1999).…”

Section: Resultsmentioning

confidence: 99%

hnRNP I is required to generate the Ca2+ signal that causes egg activation in zebrafish

et al. 2009

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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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“…Samples were then dehydrated in graded ethanol and embedded under vacuum in Epon 812 as described (6). Epon blocks were cut to 70-nm slices and were then sequentially stained with 0.04% bismuth subnitrate, saturated uranyl citrate, and 0.25% lead citrate.…”

Section: Methodsmentioning

confidence: 99%

Endocytic pathway of exogenous iron-loaded ferritin in intestinal epithelial (Caco-2) cells

Antileo

Garri

Tapia

et al. 2013

American Journal of Physiology-Gastrointestinal and Liver Physi

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Artículo de publicación ISIFerritin, a food constituent of animal and vegetal origin, is a source of dietary iron. Its hollow central cavity has the capacity to store up to 4,500 atoms of iron, so its potential as an iron donor is advantageous to heme iron, present in animal meats and inorganic iron of mineral or vegetal origin. In intestinal cells, ferritin internalization by endocytosis results in the release of its iron into the cytosolic labile iron pool. The aim of this study was to characterize the endocytic pathway of exogenous ferritin absorbed from the apical membrane of intestinal epithelium Caco-2 cells, using both transmission electron microscopy and fluorescence confocal microscopy. Confocal microscopy revealed that endocytosis of exogenous AlexaFluor 488-labeled ferritin was initiated by its engulfment by clathrin-coated pits and internalization into early endosomes, as determined by codistribution with clathrin and early endosome antigen 1 (EEA1). AlexaFluor 488-labeled ferritin also codistributed with the autophagosome marker microtubule-associated protein 1 light chain 3 (LC3) and the lysosome marker lysosomal-associated membrane protein 2 (LAMP2). Transmission electron microscopy revealed that exogenously added ferritin was captured in plasmalemmal pits, double-membrane compartments, and multivesicular bodies considered as autophagosomes and lysosomes. Biochemical experiments revealed that the lysosome inhibitor chloroquine and the autophagosome inhibitor 3-methyladenine (3-MA) inhibited degradation of exogenously added 131I-labeled ferritin. This evidence is consistent with a model in which exogenous ferritin is internalized from the apical membrane through clathrin-coated pits, and then follows a degradation pathway consisting of the passage through early endosomes, autophagosomes, and autolysosomes.This work was financed by project ICM-P05-001-F from the Millennium Scientific Initiative, Ministerio de Economía, Chile (to M. T. Núñez), and by Grants 1070840 from Fondo Nacional de Ciencia y Tecnología (to M. T. Núñez) and ACT 1111 (to S. Lavandero and M. Chiong)

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Reorganization of cytoplasm in the zebrafish oocyte and egg during early steps of ooplasmic segregation

Cited by 37 publications

References 38 publications

Dachsous1b cadherin regulates actin and microtubule cytoskeleton during early zebrafish embryogenesis

Dachsous1b cadherin regulates actin and microtubule cytoskeleton during early zebrafish embryogenesis

hnRNP I is required to generate the Ca2+ signal that causes egg activation in zebrafish

Endocytic pathway of exogenous iron-loaded ferritin in intestinal epithelial (Caco-2) cells

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