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Comparative expression analysis of transcription factor genes in the endostyle of invertebrate chordates
Author(s) -
Hiruta Jin,
Mazet Francoise,
Yasui Kinya,
Zhang Peijun,
Ogasawara Michio
Publication year - 2005
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/dvdy.20401
Subject(s) - biology , vertebrate , chordate , thyroid , transcription factor , gene , lineage (genetic) , phylogenetic tree , evolutionary biology , genetics
The endostyle of invertebrate chordates is a pharyngeal organ that is thought to be homologous with the follicular thyroid of vertebrates. Although thyroid‐like features such as iodine‐concentrating and peroxidase activities are located in the dorsolateral part of both ascidian and amphioxus endostyles, the structural organization and numbers of functional units are different. To estimate phylogenetic relationships of each functional zone with special reference to the evolution of the thyroid, we have investigated, in ascidian and amphioxus, the expression patterns of thyroid‐related transcription factors such as TTF‐2/FoxE4 and Pax2/5/8 , as well as the forkhead transcription factors FoxQ1 and FoxA . Comparative gene expression analyses depicted an overall similarity between ascidians and amphioxus endostyles, while differences in expression patterns of these genes might be specifically related to the addition or elimination of a pair of glandular zones. Expressions of Ci‐FoxE and BbFoxE4 suggest that the ancestral FoxE class might have been recruited for the formation of thyroid‐like region in a possible common ancestor of chordates. Furthermore, coexpression of FoxE4 , Pax2/5/8 , and TPO in the dorsolateral part of both ascidian and amphioxus endostyles suggests that genetic basis of the thyroid function was already in place before the vertebrate lineage. Developmental Dynamics 233:1031–1037, 2005. © 2005 Wiley‐Liss, Inc.