@article {72, title = {Wnt signaling is required for early development of zebrafish swimbladder.}, journal = {PLoS One}, volume = {6}, year = {2011}, month = {2011}, pages = {e18431}, abstract = {

BACKGROUND: Wnt signaling plays critical roles in mammalian lung development. However, Wnt signaling in the development of the zebrafish swimbladder, which is considered as a counterpart of mammalian lungs, have not been explored. To investigate the potential conservation of signaling events in early development of the lung and swimbladder, we wish to address the question whether Wnt signaling plays a role in swimbladder development.

METHODOLOGY/PRINCIPAL FINDINGS: For analysis of zebrafish swimbladder development, we first identified, by whole-mount in situ hybridization (WISH), has2 as a mesenchymal marker, sox2 as the earliest epithelial marker, as well as hprt1l and elovl1a as the earliest mesothelial markers. We also demonstrated that genes encoding Wnt signaling members Wnt5b, Fz2, Fz7b, Lef1, Tcf3 were expressed in different layers of swimbladder. Then we utilized the heat-shock inducible transgenic lines hs:Dkk1-GFP and hs:ΔTcf-GFP to temporarily block canonical Wnt signaling. Inhibition of canonical Wnt signaling at various time points disturbed precursor cells specification, organization, anterioposterior patterning, and smooth muscle differentiation in all three tissue layers of swimbladder. These observations were also confirmed by using a chemical inhibitor (IWR-1) of Wnt signaling. In addition, we found that Hedgehog (Hh) signaling was activated by canonical Wnt signaling and imposed a negative feedback on the latter.

SIGNIFICANCE/CONCLUSION: We first provided a new set of gene markers for the three tissue layers of swimbladder in zebrafish and demonstrated the expression of several key genes of Wnt signaling pathway in developing swimbladder. Our functional analysis data indicated that Wnt/β-catenin signaling is required for swimbladder early development and we also provided evidence for the crosstalk between Wnt and Hh signaling in early swimbladder development.

}, keywords = {Air Sacs, Animals, Animals, Genetically Modified, Apoptosis, Cell Differentiation, Cell Proliferation, Embryo, Nonmammalian, Epithelium, Gene Expression Regulation, Developmental, Gene Knockdown Techniques, Genetic Markers, Green Fluorescent Proteins, Heat-Shock Response, Hedgehog Proteins, Mesoderm, Models, Biological, Morphogenesis, Myocytes, Smooth Muscle, Recombinant Fusion Proteins, Reproducibility of Results, Signal Transduction, Wnt Proteins, Zebrafish, Zebrafish Proteins}, issn = {1932-6203}, doi = {10.1371/journal.pone.0018431}, author = {Yin, Ao and Korzh, Svitlana and Winata, Cecilia L and Korzh, Vladimir and Gong, Zhiyuan} } @article {73, title = {The interaction of epithelial Ihha and mesenchymal Fgf10 in zebrafish esophageal and swimbladder development.}, journal = {Dev Biol}, volume = {359}, year = {2011}, month = {2011 Nov 15}, pages = {262-76}, abstract = {

Developmental patterning and growth of the vertebrate digestive and respiratory tracts requires interactions between the epithelial endoderm and adjacent mesoderm. The esophagus is a specialized structure that connects the digestive and respiratory systems and its normal development is critical for both. Shh signaling from the epithelium regulates related aspects of mammalian and zebrafish digestive organ development and has a prominent effect on esophageal morphogenesis. The mechanisms underlying esophageal malformations, however, are poorly understood. Here, we show that zebrafish Ihha signaling from the epithelium acting in parallel, but independently of Shh, controls epithelial and mesenchymal cell proliferation and differentiation of smooth muscles and neurons in the gut and swimbladder. In zebrafish ihha mutants, the esophageal and swimbladder epithelium is dysmorphic, and expression of fgf10 in adjacent mesenchymal cells is affected. Analysis of the development of the esophagus and swimbladder in fgf10 mutant daedalus (dae) and compound dae/ihha mutants shows that the Ihha-Fgf10 regulatory interaction is realized through a signaling feedback loop between the Ihha-expressing epithelium and Fgf10-expressing mesenchyme. Disruption of this loop further affects the esophageal and swimbladder epithelium in ihha mutants, and Ihha acts in parallel to but independently of Shha in this process. These findings contribute to the understanding of epithelial-mesenchymal interactions and highlight an interaction between Hh and Fgf signaling pathways during esophagus and swimbladder development.

}, keywords = {Air Sacs, Animals, Animals, Genetically Modified, Cell Proliferation, Embryo, Nonmammalian, Epithelium, Esophagus, Female, Fibroblast Growth Factor 10, Gastrointestinal Tract, Gene Expression Regulation, Developmental, Gene Knockdown Techniques, Green Fluorescent Proteins, Hedgehog Proteins, In Situ Hybridization, Male, Membrane Proteins, Mesoderm, Microscopy, Confocal, Mutation, Protein Binding, Receptors, Cell Surface, Signal Transduction, Zebrafish, Zebrafish Proteins}, issn = {1095-564X}, doi = {10.1016/j.ydbio.2011.08.024}, author = {Korzh, Svitlana and Winata, Cecilia Lanni and Zheng, Weiling and Yang, Shulan and Yin, Ao and Ingham, Phillip and Korzh, Vladimir and Gong, Zhiyuan} } @article {71, title = {Expression of components of Wnt and Hedgehog pathways in different tissue layers during lung development in Xenopus laevis.}, journal = {Gene Expr Patterns}, volume = {10}, year = {2010}, month = {2010 Oct-Dec}, pages = {338-44}, abstract = {

Although Wnt and Hedgehog (Hh) signaling pathways play important roles in mouse lung development, these have not been explored in the development of Xenopus lung. This may be due to the lack of specific molecular markers for different layers of tissue in Xenopus lung and/or insufficient knowledge on expression patterns of Wnt and Hh signaling components in Xenopus lung. In this study, we first described the early morphogenesis of Xenopus laevis lung by using surfactant protein C (sftpc) as a marker of lung epithelium and compared it with the expression patterns of several genes of Wnt and Hh pathways in Xenopus lungs. Our data showed that wnt7b was expressed in the entire lung epithelium from stage 37 to stage 45, while two other Wnt signaling components, wnt5a and wif1 (wnt inhibitory factor 1), were expressed in the mesenchyme layer of the entire lungs through stages 39-41. We also found that sonic hedgehog (shh) was expressed at stage 41 only in the anterior, but not in the posterior part of the lungs. These results show the expression of wnt5a, wnt7b, wif1 and shh in different layers of tissue of Xenopus lungs at early developmental stages, which implies different roles of these genes in the early development of Xenopus lungs. Our study for the first time defined specific molecular markers for description of early lung development in Xenopus, as well as provided information about expression of components of Wnt and Hh pathways in early Xenopus lungs, which should be useful for future functional studies.

}, keywords = {Animals, Epithelium, Gene Expression Regulation, Developmental, Genetic Markers, Hedgehog Proteins, In Situ Hybridization, Lung, Mesoderm, Morphogenesis, Polymerase Chain Reaction, Pulmonary Surfactants, Signal Transduction, Wnt Proteins, Xenopus Proteins, Xenopus laevis}, issn = {1872-7298}, doi = {10.1016/j.gep.2010.07.005}, author = {Yin, Ao and Winata, Cecilia L and Korzh, Svitlana and Korzh, Vladimir and Gong, Zhiyuan} }