Elsevier

Developmental Biology

Volume 448, Issue 2, 15 April 2019, Pages 88-100
Developmental Biology

Transcriptional regulation of the Ciona Gsx gene in the neural plate

https://doi.org/10.1016/j.ydbio.2018.12.013Get rights and content
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Highlights

  • 376 bp Gsx non-coding cis regulatory element identified as minimal promoter.

  • Minimal promoter includes response elements for FGF- and Notch signals.

  • Minimal promoter responds to Snail- and Six3/6- mediated repression.

  • Proximal element controls precise temporal onset of gene expression.

Abstract

The ascidian neural plate consists of a defined number of identifiable cells organized in a grid of rows and columns, representing a useful model to investigate the molecular mechanisms controlling neural patterning in chordates. Distinct anterior brain lineages are specified via unique combinatorial inputs of signalling pathways with Nodal and Delta-Notch signals patterning along the medial-lateral axis and FGF/MEK/ERK signals patterning along the anterior-posterior axis of the neural plate. The Ciona Gsx gene is specifically expressed in the a9.33 cells in the row III/column 2 position of anterior brain lineages, characterised by a combinatorial input of Nodal-OFF, Notch-ON and FGF-ON. Here, we identify the minimal cis-regulatory element (CRE) of 376 bp, which can recapitulate the early activation of Gsx. We show that this minimal CRE responds in the same way as the endogenous Gsx gene to manipulation of FGF- and Notch-signalling pathways and to overexpression of Snail, a mediator of Nodal signals, and Six3/6, which is required to demarcate the anterior boundary of Gsx expression at the late neurula stage. We reveal that sequences proximal to the transcription start site include a temporal regulatory element required for the precise transcriptional onset of gene expression. We conclude that sufficient spatial and temporal information for Gsx expression is integrated in 376 bp of non-coding cis-regulatory sequences.

Keywords

Ascidian
Ciona
Gsx
Transcriptional regulation
Promoter
Neural patterning
Para-hox

Cited by (0)

1

Equal contributors.

2

Current address: Center for Advanced Biomaterials for Health Care/CRIB, Largo Barsanti e Matteucci 53 80125 Napoli, Italy.

3

Current address: Tigem (Telethon Institute of Genetics And Medicine), Via Campi Flegrei, 34, 80078 Pozzuoli Napoli, Italy.

4

Current address: Enzo Life Sciences 13, avenue Albert Einstein, 69100 Villeurbanne, France.