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Cis-regulatory control of the nodal gene, initiator of the sea urchin oral ectoderm gene network

Nam, Jongmin and Su, Yi-Hsien and Lee, Pei Yun and Robertson, Anthony J. and Coffman, James A. and Davidson, Eric H. (2007) Cis-regulatory control of the nodal gene, initiator of the sea urchin oral ectoderm gene network. Developmental Biology, 306 (2). pp. 860-869. ISSN 0012-1606. PMCID PMC2063469. doi:10.1016/j.ydbio.2007.03.033.

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Expression of the nodal gene initiates the gene regulatory network which establishes the transcriptional specification of the oral ectoderm in the sea urchin embryo. This gene encodes a TGFβ ligand, and in Strongylocentrotus purpuratus its transcription is activated in the presumptive oral ectoderm at about the 30-cell stage. Thereafter Nodal signaling occurs among all cells of the oral ectoderm territory, and nodal expression is required for expression of oral ectoderm regulatory genes. The cis-regulatory system of the nodal gene transduces anisotropically distributed cytoplasmic cues that distinguish the future oral and aboral domains of the early embryo. Here we establish the genomic basis for the initiation and maintenance of nodal gene expression in the oral ectoderm. Functional cis-regulatory control modules of the nodal gene were identified by interspecific sequence conservation. A 5′ cis-regulatory module functions both to initiate expression of the nodal gene and to maintain its expression by means of feedback input from the Nodal signal transduction system. These functions are mediated respectively by target sites for bZIP transcription factors, and by SMAD target sites. At least one SMAD site is also needed for the initiation of expression. An intron module also contains SMAD sites which respond to Nodal feedback, and in addition acts to repress vegetal expression. These observations explain the main features of nodal expression in the oral ectoderm: since the activity of bZIP factors is redox sensitive, and the initial polarization of oral vs. aboral fate is manifested in a redox differential, the bZIP sites account for the activation of nodal on the oral side; and since the immediate early signal transduction response factors for Nodal are SMAD factors, the SMAD sites account for the feedback maintenance of nodal gene expression.

Item Type:Article
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Additional Information:© 2007 Elsevier Inc. Received for publication 8 February 2007; revised 13 March 2007; accepted 23 March 2007. Available online 28 March 2007. JN appreciates Sagar Damle, Stefan Materna, Joel Smith, Paola Oliveri, Roger Revilla-i-Domingo, Andy Ransick, and Charles Titus Brown for criticisms and suggestions; Dave McClay and Cyndi Bradham for sharing their experiences with nodal with us; and Julie Hahn, Ping Dong, and Miki Yun for technical help. This work was supported by NIH grant HD-37105.
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Subject Keywords:Nodal; Oral ectoderm; Gene regulatory network; Community effect; TGF-beta; bZIP; SMAD; Sea urchin; Positive feedback regulation; Cis-regulatory analysis
Issue or Number:2
PubMed Central ID:PMC2063469
Record Number:CaltechAUTHORS:20160121-135402388
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Official Citation:Jongmin Nam, Yi-Hsien Su, Pei Yun Lee, Anthony J. Robertson, James A. Coffman, Eric H. Davidson, Cis-regulatory control of the nodal gene, initiator of the sea urchin oral ectoderm gene network, Developmental Biology, Volume 306, Issue 2, 15 June 2007, Pages 860-869, ISSN 0012-1606, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63853
Deposited By: Ruth Sustaita
Deposited On:21 Jan 2016 22:25
Last Modified:10 Nov 2021 23:22

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