Int. J. Dev. Biol. 55: 11 - 18 (2011)

https://doi.org/10.1387/ijdb.092981sy

Vol 55, Issue 1

Ciona intestinalis Noto4 contains a phosphotyrosine interaction domain and is involved in the midline intercalation of notochord cells

Original Article | Published: 23 September 2010

Shigehiro Yamada*^,1,2,3, Naoto Ueno², Nori Satoh^1,3 and Hiroki Takahashi*^,2

¹Department of Zoology, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, ²Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi and ³Marine Genomics Unit, Okinawa Institute of Science and Technology, Uruma, Okinawa, Japan

Abstract

Brachyury plays a pivotal role in the notochord formation in ascidian embryos. Ciona intestinalis Noto4 (Ci-Noto4) was isolated as a gene downstream of Ci-Bra. This gene encodes a 307 amino-acid protein with a C-terminal phosphotyrosine interaction domain (PTB/PID). Expression of Ci-Noto4 commences at the neural plate stage and is specific to notochord cells. Suppression of Ci-Noto4 levels with specific antisense morpholino oligonucleotides resulted in the formation of two rows of notochord cells owing to a lack of midline intercalation between the bilateral populations of progenitor cells. In contrast, overexpression of Ci-Noto4 by injection of a Ci-Bra(promoter):Ci-Noto4-EGFP construct into fertilized eggs disrupted the localization of notochord cells. Ci-Noto4 overexpression did not affect cellular differentiation in the notochord, muscle, mesenchyme, or nervous system. Analysis of Ci-Noto4 regions that are responsible for its function suggested significant roles for the PTB/PID and a central region, an area with no obvious sequence similarity to other known proteins. These results suggested that PTB/PID-containing Ci-Noto4 is essential for midline intercalation of notochord cells in chordate embryos.

Keywords

notochord cell, morphogenetic movement, Ci-Noto4, Ci-Bra down-stream gene