Epigenetic regulation of development : eco-evo-devo approach of m6A epitranscriptomes in the oyster Crassostrea gigas

• Main Author: Le Franc, Lorane
• 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), Normandie Université, Guillaume Rivière, Pascal Favrel
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2021
• Subjects: M6A; Oyster; RNA; Methylation; Epitranscriptomic; Épitranscriptomique; [SDV.BA]Life Sciences [q-bio]/Animal biology; Crassostrea gigas
• Online Access: https://theses.hal.science/tel-04100996; https://theses.hal.science/tel-04100996/document; https://theses.hal.science/tel-04100996/file/sygal_fusion_28552-le_franc-lorane.pdf

The RNA modification N6-methyladenosine (m6A) is a newly described regulatory layer of gene expression involved in RNA splicing, translation and stability. This epitranscriptomic pathway, composed of writers, erasers and readers, regulates key developmental steps such as MZT and cell differentiation. However, this epitranscriptomic mechanism, which is under environmental influence, shows differences between the Vertebrates and Ecdysozoans examined, which raise the question of the general conservation of an epitranscriptomic pathway in Bilaterian and especially in Lophotrochozoans. Therefore, we investigated the conservation of an m6A pathway in C. gigas by detection of m6A RNA using dotblot and mass spectrometry. Orthologues of all types of actors of the m6A machinery were characterized in silico, and the presence of functional readers was assessed by RNA pull-down/LC-MS2. The profiling of embryo-larval m6A methylomes obtained by MeRIPseq showed that the m6A level and localization were dynamic throughout oyster development. These results show a regulation of oyster segmentation, gastrulation, tissue differentiation and metamorphosis by the m6A. Finally, the study of oocyte methylomes in contrasted environmental conditions demonstrates a life trait transmission function carried by m6A in the oyster. This work demonstrates the conservation of the developmental function of m6A epitranscriptomes and their role as a vector of intergenerational life traits for the first time, to our knowledge, in a Lophotrochozoan. La méthylation de l’ARN N6-méthyladénosine (m6A) est un nouveau mécanisme de régulation de l’expression des gènes via son implication dans l’épissage, la traduction et la stabilité des transcrits. Cette voie épitranscriptomique, composée de writers, d’erasers, et des readers, régule des étapes clés du développement comme la MZT et la différenciation cellulaire. Cependant, cette voie épitranscriptomique, influencée par l’environnement, montre des différences entre les Vertébrés et Ecdysozoaires étudiés et ...