Evolution of the neuroendocrine control of the reproduction : origin and role of the kisspeptin system ?

• Main Author: Pasquier, Jérémy
• Other Authors: Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Université Pierre et Marie Curie - Paris VI, Sylvie Dufour
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2012
• Subjects: Neuroendocrinologie; Reproduction; Kisspeptine; Synténie; Anguilla; Latimeria; [SDV.BA]Life Sciences [q-bio]/Animal biology; European eel
• Online Access: https://tel.archives-ouvertes.fr/tel-00834247; https://tel.archives-ouvertes.fr/tel-00834247/document; https://tel.archives-ouvertes.fr/tel-00834247/file/ThA_se_JA_rA_my_Pasquier_2400031.pdf

The aim of this thesis was the study of the origin and evolution of the kisspeptin system, a new actor in the control of reproduction. The analysis of genomes from vertebrate species of key phylogenetical positions allowed us to re-evaluate the diversity of kisspeptins (Kiss) and their receptors (Kissr). From these data, we could propose a new classification of Kiss and Kissr families, based on phylogenetic and syntenic criteria. Moreover, we showed that both Kiss and Kissr diversities resulted from the two whole genomic duplication rounds (1R & 2R) which occurred in the vertebrate ancestors. Gene losses led, then, to the reduction of the numbers of Kiss and Kissr in vertebrates. In particular, these losses suppressed the impact of the teleost-specific 3R on the current gene numbers. The results of this thesis revealed complex evolutionary histories that have resulted in the loss or the conservation of different Kiss and Kissr, according to vertebrate lineages. In order to address the evolutionary mechanisms that may have driven the conservation of multiple Kiss and Kissr in a given organism, we investigated the European eel which presents, as we demonstrated, two Kiss and three Kissr. The study of this model highlighted a new function of kisspeptin system in vertebrates, with the discovery of an in vitro inhibition of LHβ expression by pituitary cells, while a classical stimulatory role could be exerted on GnRH at the brain level. In conclusion, this study contributed to illustrate the complexity of the kisspeptin system in vertebrates, and to clarify the classifications and the evolutionary histories of its components Notre objectif a été d'étudier l'origine et l'évolution du système kisspeptine, un nouvel acteur du contrôle de la reproduction. L'analyse de génomes d'espèces occupant des positions clés dans la classification des vertébrés nous a permis de réévaluer la diversité des kisspeptines (Kiss) ainsi que celle de leurs récepteurs (Kissr). A partir des données obtenues, nous avons pu proposer une ...