|ZFIN ID: ZDB-PUB-070920-8|
Nodal signals mediate interactions between the extra-embryonic and embryonic tissues in zebrafish
Fan, X., Hagos, E.G., Xu, B., Sias, C., Kawakami, K., Burdine, R.D., and Dougan, S.T.
|Source:||Developmental Biology 310(2): 363-378 (Journal)|
|Registered Authors:||Burdine, Rebecca, Dougan, Scott T., Fan, Xiang, Hagos, Engda, Kawakami, Koichi, Xu, Bo|
|Keywords:||Zebrafish, squint, cyclops, EVL, YSL, Nodal-related, Mesoderm, Endoderm, Extra-embryonic, SB-505124|
|PubMed:||17850782 Full text @ Dev. Biol.|
Fan, X., Hagos, E.G., Xu, B., Sias, C., Kawakami, K., Burdine, R.D., and Dougan, S.T. (2007) Nodal signals mediate interactions between the extra-embryonic and embryonic tissues in zebrafish. Developmental Biology. 310(2):363-378.
ABSTRACTIn many vertebrates, extra-embryonic tissues are important signaling centers that induce and pattern the germ layers. In teleosts, the mechanism by which the extra-embryonic yolk syncytial layer (YSL) patterns the embryo is not understood. Although the Nodal-related protein Squint is expressed in the YSL, its role in this tissue is not known. We generated a series of stable transgenic lines with GFP under the control of squint genomic sequences. In all species, nodal-related genes induce their own expression through a positive feedback loop. We show that two tissue specific enhancers in the zebrafish squint gene mediate the response to Nodal signals. Expression in the blastomeres depends upon a conserved Nodal response element (NRE) in the squint first intron, while expression in the extra-embryonic enveloping layer (EVL) is mediated by an element upstream of the transcription start site. Targeted depletion experiments demonstrate that the zebrafish Nodal-related proteins Squint and Cyclops are required in the YSL for endoderm and head mesoderm formation. Thus, Nodal signals mediate interactions between embryonic and extra-embryonic tissues in zebrafish that maintain nodal-related gene expression in the margin. Our results demonstrate a high degree of functional conservation between the extra-embryonic tissues of mouse and zebrafish.