Related Experiment Video
Updated: Aug 6, 2026
Embryo Microinjection and Electroporation in the Chordate Ciona intestinalis
Published on: October 16, 2016
Effects of U0126 and fibroblast growth factor on gene expression profile in Ciona intestinalis embryos as revealed by
Eriko Sakabe1, Nobuhiko Tanaka, Naoki Shimozono
1Department of Materials Science, Kochi University, Kochi-shi, Japan.
Abstract:
Fibroblast growth factor (FGF) induces the notochord and mesenchyme in ascidian embryos, via extracellular signal-regulated kinase (ERK) that belongs to the mitogen-activated protein kinase (MAPK) family. A cDNA microarray analysis was carried out to identify genes affected by an inhibitor of MAPK/ERK kinase (MEK), U0126, in embryos of the ascidian Ciona intestinalis. Data obtained from the microarray and in situ hybridization suggest that the majority of genes are downregulated by U0126 treatment. Genes that were downregulated in U0126-treated embryos included Ci-Bra and Ci-Twist-like1 that are master regulatory genes of notochord and mesenchyme differentiation, respectively. The plasminogen mRNA was downregulated by U0126 in presumptive endoderm cells. This suggests that a MEK-mediated extracellular signal is necessary for gene expression in tissues whose specification does not depend on cell-to-cell interaction. Among 85 cDNA clusters that were not affected by U0126, 30 showed mitochondria-like mRNA localization in the nerve cord/muscle lineage blastomeres in the equatorial region. The expression level and asymmetric distribution of these mRNA were independent of MEK signaling.
Insights
Fibroblast growth factor (FGF) signaling regulates ascidian development via mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathways. Inhibiting MAPK/ERK kinase (MEK) with U0126 downregulates key developmental genes, including those for notochord and mesenchyme, and affects endoderm gene expression.
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- Fibroblast growth factor (FGF) signaling is crucial for ascidian embryonic development, particularly notochord and mesenchyme formation.
- This signaling pathway involves the mitogen-activated protein kinase (MAPK) cascade, specifically extracellular signal-regulated kinase (ERK).
Purpose of the Study:
- To identify genes regulated by MAPK/ERK kinase (MEK) signaling in ascidian embryos using cDNA microarray analysis.
- To investigate the role of MEK signaling in gene expression during early embryonic development in Ciona intestinalis.
Main Methods:
- Treatment of Ciona intestinalis embryos with U0126, a specific inhibitor of MEK.
- cDNA microarray analysis to assess global gene expression changes.
- In situ hybridization to validate gene expression patterns.
Main Results:
- U0126 treatment predominantly downregulated gene expression in ascidian embryos.
- Key developmental regulatory genes, Ci-Bra (notochord) and Ci-Twist-like1 (mesenchyme), were significantly downregulated.
- Plasminogen mRNA expression in presumptive endoderm cells was also reduced by U0126, indicating MEK-dependent signaling in non-cell-cell interaction-dependent tissues.
- A subset of genes with mitochondria-like mRNA localization in nerve cord/muscle lineage blastomeres showed MEK-independent expression.
Conclusions:
- MEK-mediated extracellular signaling is essential for the expression of specific genes, including master regulatory genes for notochord and mesenchyme differentiation in ascidians.
- This signaling pathway plays a role in gene expression within tissues where specification does not rely on direct cell-to-cell contact.
- Certain mRNA localization patterns in the nerve cord/muscle lineage are independent of MEK signaling.
