Original Article

Development Genes and Evolution

, Volume 218, Issue 11, pp 667-680

First online:

The amphioxus genome enlightens the evolution of the thyroid hormone signaling pathway

  • Mathilde ParisAffiliated withInstitut de Génomique Fonctionnelle de Lyon, CNRS UMR5242–INRA 1288–ENS–UCBL, IFR128 BioSciences Lyon-Gerland, Ecole Normale Supérieure de Lyon
  • , Frédéric BrunetAffiliated withInstitut de Génomique Fonctionnelle de Lyon, CNRS UMR5242–INRA 1288–ENS–UCBL, IFR128 BioSciences Lyon-Gerland, Ecole Normale Supérieure de Lyon
  • , Gabriel V. MarkovAffiliated withInstitut de Génomique Fonctionnelle de Lyon, CNRS UMR5242–INRA 1288–ENS–UCBL, IFR128 BioSciences Lyon-Gerland, Ecole Normale Supérieure de Lyon
  • , Michael SchubertAffiliated withInstitut de Génomique Fonctionnelle de Lyon, CNRS UMR5242–INRA 1288–ENS–UCBL, IFR128 BioSciences Lyon-Gerland, Ecole Normale Supérieure de Lyon
  • , Vincent LaudetAffiliated withInstitut de Génomique Fonctionnelle de Lyon, CNRS UMR5242–INRA 1288–ENS–UCBL, IFR128 BioSciences Lyon-Gerland, Ecole Normale Supérieure de Lyon Email author 

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Abstract

Thyroid hormones (THs) have pleiotropic effects on vertebrate development, with amphibian metamorphosis as the most spectacular example. However, developmental functions of THs in non-vertebrate chordates are largely hypothetical and even TH endogenous production has been poorly investigated. In order to get better insight into the evolution of the thyroid hormone signaling pathway in chordates, we have taken advantage of the recent release of the amphioxus genome. We found amphioxus homologous sequences to most of the genes encoding proteins involved in thyroid hormone signaling in vertebrates, except the fast-evolving thyroglobulin: sodium iodide symporter, thyroid peroxidase, deiodinases, thyroid hormone receptor, TBG, and CTHBP. As only some genes encoding proteins involved in TH synthesis regulation were retrieved (TRH, TSH receptor, and CRH receptor but not their corresponding receptors and ligands), there may be another mode of upstream regulation of TH synthesis in amphioxus. In accord with the notion that two whole genome duplications took place at the base of the vertebrate tree, one amphioxus gene often corresponded to several vertebrate homologs. However, some amphioxus specific duplications occurred, suggesting that several steps of the TH pathway were independently elaborated in the cephalochordate and vertebrate lineages. The present results therefore indicate that amphioxus is capable of producing THs. As several genes of the TH signaling pathway were also found in the sea urchin genome, we propose that the thyroid hormone signaling pathway is of ancestral origin in chordates, if not in deuterostomes, with specific elaborations in each lineage, including amphioxus.

Keywords

Branchiostoma floridae Cephalochordate Chordate Development Evolution Thyroid hormone Endostyle