title: Spatio-Temporal Gene Expression Profiling during In Vivo Early Ovarian Folliculogenesis: Integrated Transcriptomic Study and Molecular Signature of Early Follicular Growth.
abstract: BACKGROUND
  The successful achievement of early ovarian folliculogenesis is important for fertility and reproductive life span. This complex biological process requires the appropriate expression of numerous genes at each developmental stage, in each follicular compartment. Relatively little is known at present about the molecular mechanisms that drive this process, and most gene expression studies have been performed in rodents and without considering the different follicular compartments.
  
  
  RESULTS
  We used RNA-seq technology to explore the sheep transcriptome during early ovarian follicular development in the two main compartments: oocytes and granulosa cells. We documented the differential expression of 3,015 genes during this phase and described the gene expression dynamic specific to these compartments. We showed that important steps occurred during primary/secondary transition in sheep. We also described the in vivo molecular course of a number of pathways. In oocytes, these pathways documented the chronology of the acquisition of meiotic competence, migration and cellular organization, while in granulosa cells they concerned adhesion, the formation of cytoplasmic projections and steroid synthesis. This study proposes the involvement in this process of several members of the integrin and BMP families. The expression of genes such as Kruppel-like factor 9 (KLF9) and BMP binding endothelial regulator (BMPER) was highlighted for the first time during early follicular development, and their proteins were also predicted to be involved in gene regulation. Finally, we selected a data set of 24 biomarkers that enabled the discrimination of early follicular stages and thus offer a molecular signature of early follicular growth. This set of biomarkers includes known genes such as SPO11 meiotic protein covalently bound to DSB (SPO11), bone morphogenetic protein 15 (BMP15) and WEE1 homolog 2 (S. pombe)(WEE2) which play critical roles in follicular development but other biomarkers are also likely to play significant roles in this process.
  
  
  CONCLUSIONS
  To our knowledge, this is the first in vivo spatio-temporal exploration of transcriptomes derived from early follicles in sheep.
authors.affiliation: INRA, UMR 1388 GenPhySE (Génétique, Physiologie et Systèmes d'Elevage), F-31326 Castanet-Tolosan, France.|Université de Toulouse, INP, ENSAT, GenPhySE (Génétique, Physiologie et Systèmes d'Elevage), F-31326 Castanet-Tolosan, France.|Université de Toulouse, INP, ENVT, GenPhySE (Génétique, Physiologie et Systèmes d'Elevage), F-31076 Toulouse, France.
authors.forename: Agnes
authors.initials: A
authors.lastname: Bonnet
authors.affiliation: INRA, UMR 1388 GenPhySE (Génétique, Physiologie et Systèmes d'Elevage), F-31326 Castanet-Tolosan, France.|Université de Toulouse, INP, ENSAT, GenPhySE (Génétique, Physiologie et Systèmes d'Elevage), F-31326 Castanet-Tolosan, France.|Université de Toulouse, INP, ENVT, GenPhySE (Génétique, Physiologie et Systèmes d'Elevage), F-31076 Toulouse, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Servin
authors.affiliation: INRA, UMR 1388 GenPhySE (Génétique, Physiologie et Systèmes d'Elevage), F-31326 Castanet-Tolosan, France.|Université de Toulouse, INP, ENSAT, GenPhySE (Génétique, Physiologie et Systèmes d'Elevage), F-31326 Castanet-Tolosan, France.|Université de Toulouse, INP, ENVT, GenPhySE (Génétique, Physiologie et Systèmes d'Elevage), F-31076 Toulouse, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Mulsant
authors.affiliation: INRA, UMR1198 Biologie du Développement et de la Reproduction, F-78350 Jouy-en-Josas, France.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Mandon-Pepin
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D006107:Granulosa Cells / Q000378:metabolism / Q000502:physiology; D008540:Meiosis / Q000235:genetics; D006080:Ovarian Follicle / Q000254:growth & development* / Q000378:metabolism; D010053:Ovary / Q000254:growth & development / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012756:Sheep