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Les hormones thyroïdiennes, leurs récepteurs et l'évolution de la métamorphose chez les Chordés.

Abstract : IN AN ATTEMPT TO UNDERSTAND HOW THE REGULATION OF DEVELOPMENT EVOLVES, ATTENTION HAS BEEN PUT ON TRANSCRIPTION FACTORS, WHICH REGULATE GENE EXPRESSION DURING DEVELOPMENT. AMONG THESE FACTORS, NUCLEAR HORMONE RECEPTORS (NRS) HAVE A PECULIAR STATUS LINKED TO THEIR LIGAND-DEPENDENT ACTIVITY. I STUDIED DURING MY THESIS THE EVOLUTION OF THE ESTROGEN RECEPTOR (ER) AND OF THE THYROID HORMONE RECEPTOR (TR) IN CHORDATES LIKE VERTEBRATES BY FOCUSING ON THE MOST BASAL CHORDATE AMPHIOXUS. IN PARTICULAR, I STUDIED HOW METAMORPHOSIS EVOLVED IN THE CHORDATE LINEAGE, AS A PARADIGM OF THE EVOLUTION OF A DEVELOPMENTAL PROCESS. ALTHOUGH MOST CHORDATES METAMORPHOSE, THE CORRESPONDING MORPHOLOGICAL CHANGES VARY EXTENSIVELY FROM ONE SPECIES TO ANOTHER. DOES THE MOLECULAR DETERMINISM OF METAMORPHOSIS IN THIS GROUP REFLECT THIS MORPHOLOGICAL DIVERSITY? IN THE WELL-STUDIED VERTEBRATES, METAMORPHOSIS IS TRIGGERED BY THYROID HORMONES (THS) BINDING TO THEIR RECEPTOR TR, MEMBER OF THE NR SUPERFAMILY. COMBINED BIOCHEMICAL AND PHYLOGENETIC APPROACHES ALLOWED ME TO ESTABLISH THAT AMPHIOXUS PRODUCES VARIOUS THS THROUGH METABOLIC PATHWAYS HOMOLOGOUS TO VERTEBRATE ONES. THEN I SHOWED THAT TH-DEPENDENT TR ACTIVATION IS ESSENTIAL FOR METAMORPHOSIS INDUCTION IN AMPHIOXUS, LIKE IN VERTEBRATES.. CONSEQUENTLY THE HOMOLOGY OF METAMORPHOSIS IN CHORDATES IS REVEALED BY THE CONSERVATION OF ITS TRIGGERING MECHANISM. THIS SUGGESTS THAT THE EVOLUTION OF METAMORPHOSIS IN CHORDATES IS MARKED BY THE CONSERVATION OF THE COUPLE TH/TR WHEREAS OTHER PARTS OF THE REGULATORY NETWORK MAY CHANGE TO UNDERLIE THE MORPHOLOGICAL DIVERSITY OBSERVED NOWADAYS.
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https://tel.archives-ouvertes.fr/tel-00366311
Contributor : Mathilde Paris <>
Submitted on : Friday, March 6, 2009 - 2:57:57 PM
Last modification on : Wednesday, January 6, 2021 - 8:50:02 PM
Long-term archiving on: : Friday, October 12, 2012 - 1:00:37 PM

Identifiers

  • HAL Id : tel-00366311, version 1
  • PRODINRA : 249916

Citation

Mathilde Paris. Les hormones thyroïdiennes, leurs récepteurs et l'évolution de la métamorphose chez les Chordés.. Biochimie [q-bio.BM]. Ecole normale supérieure de lyon - ENS LYON, 2008. Français. ⟨tel-00366311⟩

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