title: Cerberus is a feedback inhibitor of Nodal asymmetric signaling in the chick embryo.
abstract: The TGF-beta-related molecule Nodal plays an essential and conserved role in left-right patterning of the vertebrate embryo. Previous reports have shown that the zebrafish and mouse Cerberus-related proteins Charon and Cerberus-like-2 (Cerl-2), respectively, act in the node region to prevent the Nodal signal from crossing to the right side, whereas chick Cerberus (cCer) has an unclear function in the left-side mesoderm. In this study, we investigate the transcriptional regulation and function of cCer in left-right development. By analyzing the enhancer activity of cCer 5' genomic sequences in electroporated chick embryos, we identified a cCer left-side enhancer that contains two FoxH1 and one SMAD binding site. We show that these Nodal-responsive elements are necessary and sufficient for the activation of transcription in the left-side mesoderm. In transgenic mouse embryos, cCer regulatory sequences behave as in chick embryos, suggesting that the cis-regulatory sequences of Cerberus-related genes have diverged during vertebrate evolution. Moreover, our findings from cCer overexpression and knockdown experiments indicate that cCer is a negative-feedback regulator of Nodal asymmetric signaling. We propose that cCer and mouse Cerl-2 have evolved distinct regulatory mechanisms but retained a conserved function in left-right development, which is to restrict Nodal activity to the left side of the embryo.
authors.affiliation: Instituto Gulbenkian de Ciência, 2781-901 Oeiras, Portugal. atavares@igc.gulbenkian.pt
authors.forename: Ana Teresa
authors.initials: AT
authors.lastname: Tavares
authors.forename: Sofia
authors.initials: S
authors.lastname: Andrade
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Silva
authors.forename: José António
authors.initials: JA
authors.lastname: Belo
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics / Q000502:physiology*; D002642:Chick Embryo; D017931:DNA Primers / Q000235:genetics; D018274:Electroporation; D025461:Feedback, Physiological / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008648:Mesoderm / Q000502:physiology; D051379:Mice; D055457:Nodal Protein; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D036341:Intercellular Signaling Peptides and Proteins; D055457:Nodal Protein; C526008:Nodal protein, mouse; D016212:Transforming Growth Factor beta