Analysis of the Transcription Regulatory Mechanism of Otx During the Development of the Sensory Vesicle in Ciona intestinalis

Abstract

Establishment of the anterior-posterior axis is an important event in the development of bilateral animals. A homeodomain transcription factor, Otx, is important for the formation of the anterior part of the embryo, and its mRNA is expressed in a continuous manner in a wide range of animals. This pattern of expression is thought to be important for the formation of anterior neural structures, but the mechanism that regulates Otx expression remains largely unknown. Towards understanding how the transcription of Otx is maintained in the cells of anterior neural structure, the sensory vesicle, during embryogenesis, we examined transcription regulatory mechanisms of Otx, using embryos of the ascidian, Ciona intestinalis, from the gastrula to tailbud stages, which have not been studied previously. We identified two genomic regions capable of mimicking the Otx expression pattern from the gastrula to tailbud stages. Putative transcription factor binding sites required for this activity were identified. Notably, distinct sets of transcription factor binding sites were required at different developmental stages for the expression of Otx, suggesting that the continuity of Otx is supported by distinct transcriptional mechanisms in the gastrula and neurula stages. Along with previous studies using Halocynthia roretzi, the present results provide insight into the evolution of transcriptional regulatory mechanism of Otx.

The complete cell lineage and MAPK- and Otx-dependent specification of the dopaminergic cells in the Ciona brain

“…Otx is continuously expressed in the DA-lineage cells from cleavage to at least the tailbud stages, and the transcription regulatory mechanisms of Otx change several times during the development (Hudson and Lemaire, 2001;Oonuma et al, 2014). It has been suggested that from the cleavage to the early gastrula stages, Otx expression is regulated by the transcription factors GATA and Ets activated by FGF signaling (Bertrand et al, 2003), whereas the transcription factors Sox, Zic and Fox have been suggested to regulate the transcription of Otx from the mid to late gastrula stages (Oonuma et al, 2014). Either of these two pathways, i.e.…”