Project description:Separate transcription profiling of oocytes and granulosa cells for each follicle stage: primordial (PD), primary (PM), secondary (SC) follicles and the small antral stage (SA) obtained by Laser Capture Microdissection (LCM) and RNAseq. The purpose of this study was to describe global gene expression during early ovarian folliculogenesis for each follicular compartment, to identify differential and specific gene expression between the 2 follicular compartments and during follicular development, to investigate specific function and pathways and to explore bi-directional communication between oocytes and GC.
Project description:Background Correct achievement of early ovarian folliculogenesis is a crucial phase for further ovarian function. This process is closely regulated by cell-cell interactions and coordinated expression of genes from oocyte and granulosa cells. But, despite of the large number of studies, little is known about the precise gene expression patterns driving early folliculogenesis. The experimental limitations concerned the very small size of these follicles and the mixture of the different developmental stages within an ovary that make the study of isolated follicular components much more difficult. The recently developed laser capture microdissection (LCM) technique coupled with microarrays experiments is promising in addressing the molecular specificity of each follicular compartment. Nevertheless, the isolation of unique cells or group of cells is still challenging to maintain RNA quality during this process and to obtain sufficient amount of RNA. In this study, we described a method allowing the analysis of oocyte and granulosa cells gene expression during the first stages of sheep early folliculogenesis. Results First we developed a new fixation protocol using a frizzed 70% ethanol fixation solution that ensures correct single cell capture and RNA integrity during microdissection time. After LCM capture of the compartments and follicular stages, RNA extraction and amplification, the expression of 6 oocyte-specific genes (SOHLH2, MAEL, MATER, VASA, GDF9, BMP15) and 3 granulosa cell-specific genes (KITLG, GATA4, AMH) confirmed the purity of the samples and documented their ovine expression profiles. Then, using bovine Affymetrix chip, we identified for the first time, a global gene expression for each follicular compartment during early developmental stages. Particularly the granulosa cell data set is quite unique. 1050 granulosa cell specific transcripts compared to oocyte and 759 oocyte specific transcripts were detected. The analysis of the expression of 2 genes (SIRT7, FST) confirmed this specificity of expression. Finally, the integration of the data stated the 3 main physiological events involved in early folliculogenesis and provided descriptive elements that confirmed the relevance and the potential of the LCM-derived RNAs. Conclusions This method should contribute through an additional genome wide expression profiling to give insights on molecular mechanisms involved in stage transitions and cell type interplays.
Project description:Background Correct achievement of early ovarian folliculogenesis is a crucial phase for further ovarian function. This process is closely regulated by cell-cell interactions and coordinated expression of genes from oocyte and granulosa cells. But, despite of the large number of studies, little is known about the precise gene expression patterns driving early folliculogenesis. The experimental limitations concerned the very small size of these follicles and the mixture of the different developmental stages within an ovary that make the study of isolated follicular components much more difficult. The recently developed laser capture microdissection (LCM) technique coupled with microarrays experiments is promising in addressing the molecular specificity of each follicular compartment. Nevertheless, the isolation of unique cells or group of cells is still challenging to maintain RNA quality during this process and to obtain sufficient amount of RNA. In this study, we described a method allowing the analysis of oocyte and granulosa cells gene expression during the first stages of sheep early folliculogenesis. Results First we developed a new fixation protocol using a frizzed 70% ethanol fixation solution that ensures correct single cell capture and RNA integrity during microdissection time. After LCM capture of the compartments and follicular stages, RNA extraction and amplification, the expression of 6 oocyte-specific genes (SOHLH2, MAEL, MATER, VASA, GDF9, BMP15) and 3 granulosa cell-specific genes (KITLG, GATA4, AMH) confirmed the purity of the samples and documented their ovine expression profiles. Then, using bovine Affymetrix chip, we identified for the first time, a global gene expression for each follicular compartment during early developmental stages. Particularly the granulosa cell data set is quite unique. 1050 granulosa cell specific transcripts compared to oocyte and 759 oocyte specific transcripts were detected. The analysis of the expression of 2 genes (SIRT7, FST) confirmed this specificity of expression. Finally, the integration of the data stated the 3 main physiological events involved in early folliculogenesis and provided descriptive elements that confirmed the relevance and the potential of the LCM-derived RNAs. Conclusions This method should contribute through an additional genome wide expression profiling to give insights on molecular mechanisms involved in stage transitions and cell type interplays. The 2 ovine follicular compartments (i.e. granulosa cells (G) and oocytes (O) were captured using LCM technology for each early stage (primordial (Pd), primary (Pm), secondary (Sec) follicles. The RNA of each group was extracted using Picopure RNA Isolation kit (Arcturus) and subjected to 2 round T7 amplification (RiboAmp®HS PLUS kit, Arcturus). Ovine microarray experiments were performed using the Affymetrix Bovine Expression Array. First the quality of the cross-species hybridizations was checked by comparison of hybridization data of ovine fetal ovary RNA with bovine fetal ovary ones, generated with the Affymetrix standard protocol (protocole 1). Then, three biotin-labeling protocols were compared from ovine fetal ovary total RNA: protocol 1; protocol 2 (Biotin-labeled cRNAs were synthesized following Affymetrix protocol using the second-round cDNAs from RiboAmp®HS kit as templates); protocol 3 (Arcturus biotin turboTM labeling kit from aRNA after the 2 round amplification using RiboAmp®HS kit). Last , one LCM-derived aRNA sample of each group was labeled using the Arcturus biotin turboTM labeling kit (protocol 3) and hybridized to Affymetrix Bovine Expression arrays. Images were interpreted using Microarray Suite version 5.0 (MAS 5.0) in GCOS with scaling (100) and without normalization.
Project description:Obesity is known to affect female reproduction, as evidenced by obese patients suffering from subfertility and abnormal oogenesis. However, the underlying mechanisms by which obesity impairs folliculogenesis are poorly documented. Here, we performed comprehensive single-cell transcriptome analysis in both regular diet (RD) and obese mouse models to systematically uncover how obesity affects ovarian follicle cells and their interactions. We found an increased proportion of Inhbb highly expressed granulosa cells (GCs) among all the GC subpopulations in obese mice. Under obese conditions, excessive androgen secreted from endocrine theca cells (ETCs) may contribute to the imbalanced change of GC subtypes through ETCs-GCs interactions. This is alleviated by enzalutamide, an androgen receptor antagonist. We also identified and confirmed typical GC markers, such as Marcks and Prkar2b, for sensitive evaluation of female fertility in obesity. These data represent a resource for studying transcriptional networks and cell-cell interactions during folliculogenesis under physiological and pathological conditions.
Project description:BACKGROUND: Successful early folliculogenesis is crucial for female reproductive function. It requires appropriate gene specific expression of the different types of ovarian cells at different developmental stages. To date, most gene expression studies on the ovary were conducted in rodents and did not distinguish the type of cell. In mono-ovulating species, few studies have addressed gene expression profiles and mainly concerned human oocytes. RESULTS: We used a laser capture microdissection method combined with RNA-seq technology to explore the transcriptome in oocytes and granulosa cells (GCs) during development of the sheep ovarian follicle. We first documented the expression profile of 15 349 genes, then focused on the 5 129 genes showing differential expression between oocytes and GCs. Enriched functional categories such as oocyte meiotic arrest and GC steroid synthesis reflect two distinct cell fates. We identified the implication of GC signal transduction pathways such as SHH, WNT and RHO GTPase. In addition, signaling pathways (VEGF, NOTCH, IGF1, etc.) and GC transzonal projections suggest the existence of complex cell-cell interactions. Finally, we highlighted several transcription regulators and specifically expressed genes that likely play an important role in early folliculogenesis. CONCLUSIONS: To our knowledge, this is the first comprehensive exploration of transcriptomes derived from in vivo oocytes and GCs at key stages in early follicular development in sheep. Collectively, our data advance our understanding of early folliculogenesis in mono-ovulating species and will be a valuable resource for unraveling human ovarian dysfunction such as premature ovarian failure (POF).
Project description:Female fertility is determined in part by the size and development of the primordial follicle pool. The current study investigates the role of glial cell-line derived neurotrophic factor (GDNF) in the regulation of primordial follicle development in the ovary. Ovaries from four-day old female rat pups were maintained in organ culture for ten days in the absence (control) or presence of GDNF or kit ligand/stem cell factor (KL). Ovaries treated with GDNF contained a significant increase in developing follicles, similar to that observed with KL treatment previously shown to promote follicle development. The actions of GDNF on the ovarian transcriptome were investigated with a microarray analysis. Immunohistochemical studies demonstrated that GDNF is localized to oocyte cytoplasm in follicles of all developmental stages, as well as to cumulus granulosa cells and theca cells in antral follicles. GDNF receptor alpha 1 (GFRalpha1) staining was localized to oocyte cytoplasm of primordial and primary follicles, and at reduced levels in oocytes of antral follicles. GFRalpha1 was present in mural granulosa cells of antral follicles, theca cells, and the ovarian surface epithelium. The localization studies were confirmed with molecular analysis. Microarray analysis was used to identify changes in the ovarian transcriptome and further elucidate the signaling network regulating early follicle development. Observations indicate that GDNF promotes primordial follicle development and mediates autocrine and paracrine cell-cell interactions required during folliculogenesis. In contrast to the testis, ovarian GDNF is predominantly produced by germ cells (oocytes) rather than somatic cells. Keywords: expression analysis, glial derived neurotrophic factor, follicle transition, ovary