Antagonistic interactions in the zebrafish midline prior to the emergence of asymmetric gene expression are important for left-right patterning.

TitleAntagonistic interactions in the zebrafish midline prior to the emergence of asymmetric gene expression are important for left-right patterning.
Publication TypeJournal Article
Year of Publication2016
AuthorsBurdine, RD, Grimes, DT
JournalPhilos Trans R Soc Lond B Biol Sci
Volume371
Issue1710
Date Published2016 12 19
ISSN1471-2970
Abstract

Left-right (L-R) asymmetry of the internal organs of vertebrates is presaged by domains of asymmetric gene expression in the lateral plate mesoderm (LPM) during somitogenesis. Ciliated L-R coordinators (LRCs) are critical for biasing the initiation of asymmetrically expressed genes, such as nodal and pitx2, to the left LPM. Other midline structures, including the notochord and floorplate, are then required to maintain these asymmetries. Here we report an unexpected role for the zebrafish EGF-CFC gene one-eyed pinhead (oep) in the midline to promote pitx2 expression in the LPM. Late zygotic oep (LZoep) mutants have strongly reduced or absent pitx2 expression in the LPM, but this expression can be rescued to strong levels by restoring oep in midline structures only. Furthermore, removing midline structures from LZoep embryos can rescue pitx2 expression in the LPM, suggesting the midline is a source of an LPM pitx2 repressor that is itself inhibited by oep Reducing lefty1 activity in LZoep embryos mimics removal of the midline, implicating lefty1 in the midline-derived repression. Together, this suggests a model where Oep in the midline functions to overcome a midline-derived repressor, involving lefty1, to allow for the expression of left side-specific genes in the LPM.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.

DOI10.1098/rstb.2015.0402
Alternate JournalPhilos. Trans. R. Soc. Lond., B, Biol. Sci.
PubMed ID27821532
PubMed Central IDPMC5104502
Grant ListR01 HD048584 / HD / NICHD NIH HHS / United States