Dynamics of the transcriptional landscape during human fetal testis and ovary development

Acknowledgements We thank all members of the SEQanswers forums for helpful advice; Steven Salzberg and Cole Trapnell for continuous support with the ‘Tuxedo’ suite; and the UCSC Genome team members. Sequencing was performed by the GenomEast platform, a member of the ‘France Génomique’ consortium (ANR-10-INBS-0009). We thank Ms Linda Robertson, Ms Margaret Fraser, Ms Samantha Flannigan (University of Aberdeen) and the staff at Grampian NHS Pregnancy Counselling Service and all the staff of the Department of Obstetrics and Gynecology of the Rennes Sud Hospital for their expert assistance and help, and the participating women, without whom this study would not have been possible. The authors are grateful for Ms Gersende Lacombe and Mr Laurent Deleurme from the Biosit CytomeTri cytometry core facility of Rennes 1 University. Funding French National Institute of Health and Medical Research (Inserm); University of Rennes 1; French School of Public Health (EHESP); Swiss National Science Foundation [SNF n° CRS115_171007 to B.J.]; the French National Research Agency [ANR n° 16-CE14-0017-02 and n°18-CE14-0038-02 to F.C]; Medical Research Council [MR/L010011/1 to PAF]; European Community’s Seventh Framework Programme (FP7/2007–2013) [under grant agreement no 212885 to PAF]; European Union’s Horizon 2020 Research and Innovation Programme [under grant agreement no 825100 to P.A.F. and S.M.G.].Peer reviewedPostprin

Dynamics of the transcriptional landscape during human fetal testis development.

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Dynamics of the transcriptional landscape during human fetal gonad development and its alteration by endocrine disruptors

Les organes centraux du tractus urogénital sont le testicule et l’ovaire, qui assurent la production de gamètes et d’hormones, et donc la fertilité de l’individu. Ces deux organes, parfaitement distincts et complémentaires, ont pour origine une gonade bipotentielle qui s’engagera vers une trajectoire de différenciation masculine ou féminine au cours de la vie fœtale. Les deux gonades vont par la suite subir plusieurs phases de différenciation et de développement de leurs populations cellulaires, afin d’acquérir leurs fonctions propres qui leur permettront d’assumer leur rôle à l’âge adulte. Depuis plus d’une quinzaine d’années, le concept de syndrome de dysgénésie testiculaire fait état d’un lien entre l’exposition du fœtus à des composés environnementaux et des anomalies du tractus urogénital. Bien que sujette à de vifs débats au sein de la communauté scientifique, cette hypothèse a attiré l’attention de la recherche sur les conséquences de l’exposition des mères aux xénobiotiques sur l’enfant à naître. La différenciation et le développement des gonades fœtales sont gouvernés par des programmes d’expression spécifiques de chaque sexe, dont de nombreuses zones d’ombres subsistent, notamment concernant la fraction non-codante exprimée par le génome humain. La première partie de cette thèse de doctorat présente, pour la première fois, le paysage transcriptionnel contrôlant ces processus complexes entre la 6ième et 17ième semaine de développement chez l’Homme. Grâce à l’avènement des technologies de transcriptomique, il est désormais possible d’identifier et d’observer l’expression des gènes de manière sensible et sans a priori. Le RNA-seq m’a donc permis de décrire de manière exhaustive la dynamique d’expression des gènes, pendant les stades précoces de la différenciation sexuelle, jusqu’aux phénomènes plus tardifs conduisant aux linéages des différentes populations cellulaires spécifiques du testicule et de l’ovaire. Dans une deuxième partie, mon travail de recherche s’est attaché à étudier l’impact de deux perturbateurs endocriniens suspectés, l’ibuprofène et le chlordécone, sur le programme d’expression du testicule fœtal humain. L’utilisation du RNA-seq m’a permis de définir et de comparer la signature toxicogénomique de chaque molécule afin de contribuer à la compréhension de leur mécanisme d’action et d’identifier les populations cellulaires affectées. Enfin, face à l’essor des technologies ultra-haut-débit dans les sciences de la vie, y compris dans les domaines de la reproduction, j’ai activement participé au déploiement d’une nouvelle version du Reprogenomic Viewer dans la dernière partie de ma thèse (http://rgv.genouest.org). Cet outil nternet a pour vocation de centraliser et de rendre accessibles les données de séquençage accumulées au sein de la communauté de la reproduction via des outils de visualisation intuitifs.Fetal life is a crucial period for sexual reproduction when bipotential gonads differentiate into either a testis or an ovary. Gaining insights into the complex molecular events underlying this process is central to a better understanding of disorders of sexual development. The present work intends to improve the knowledge on molecular pathways at play during gonad development in humans using RNA-sequencing. This project particularly seeks to identify early transcriptional events that may play critical role in the regulatory network driving human sexual differentiation. To address this issue, we defined the transcriptional landscape of fetal human gonads by sequencing total RNA extracted from testes and ovaries between 6 and 17 gestational weeks. The resulting paired-end reads were mapped on the human genome and then assembled into transcripts using the Tuxedo suite. We next defined a high-confidence set of transcripts showing differential expression across samples. Clusters of co-expressed genes were subjected to functional analysis. The analysis of this massive RNA-seq dataset has led to a high-confidence set of 35,194 assembled transcripts; among which 32,391 known and novel isoforms coding genes (mRNAs), 1,209 to long non-coding (lnc) RNAs and 318 to novel unannotated transcripts/genes (NUTs). The dynamic of transcriptional landscape occurring during human fetal gonads development has been described and new genes and interesting candidates, including new genes, have been highlighted as potential key genes governing this biological process. The second interest of this work was the study of the impact of two endocrine disruptors, ibuprofene and chlordecone, on human fetal testis using RNA-seq. The transcriptional alteration induced by these compound in the gonad allowed a deeper understanding of their mechanisms of action of endocrine disruption. The last part of this work was the development of a new version of the ReproGenomics Viewer (http://rgv.genouest.org), a web tool dedicated to the integration and accumulation of sequencing data from studies performed in the field of reproduction

Dynamics of the transcriptional landscape during human fetal gonad development

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New transcriptomic tools to understand testis development and functions

International audienceThe testis plays a central role in the male reproductive system - secreting several hormones including male steroids and producing male gametes. A complex and coordinated molecular program is required for the proper differentiation of testicular cell types and maintenance of their functions in adulthood. The testicular transcriptome displays the highest levels of complexity and specificity across all tissues in a wide range of species. Many studies have used high-throughput sequencing technologies to define the molecular dynamics and regulatory networks in the testis as well as to identify novel genes or gene isoforms expressed in this organ. This review intends to highlight the complementarity of these transcriptomic studies and to show how the use of different sequencing protocols contribute to improve our global understanding of testicular biology

Etude d’un réseau toxico-génomique pondéré pour la prédiction in silico de la toxicité des substances chimiques

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ChemPSy : Identification, classification et priorisation de nouveaux perturbateurs endocriniens par intégration massive de données de toxicogénomiques

National audienceThe aim of ChemPSy (Chemical Prioritization System) is to provide an innovative tool based on several bioinformatics and biostatistics methodologies to analyze and integrate massive toxicogenomics datasets. Specific objectives include: (1) classification of chemicals based on transcriptional signatures, i.e. the set of genes whose expression is known to be positively or negatively altered after an exposure to these compounds; (2) the association of classes with human pathologies or deleterious phenotypes, i.e. classes containing toxicants with well-known effects; (3) the prediction of novel reprotoxicants and/or endocrine disruptors based on transcriptional signature similarities with known chemicals affecting testis development and function.(Intro.

Dynamics of the transcriptional landscape during human gonad development from fetal to adulthood

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Dynamics of the transcriptional landscape during human fetal testis development.

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The ReproGenomics Viewer: a multi-omics and cross-species resource compatible with single-cell studies for the reproductive science community

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