Project description:The molecular mechanisms that regulate the pivotal transformation processes observed in the follicular wall following the pre-ovulatory LH-surge, are still not established, particularly for cells of the thecal layer. To elucidate thecal and granulosa cell type-specific biological functions and signaling pathways, large dominant bovine follicles were collected before and 21 hrs after an exogenous GnRH induced LH surge. Because LH receptor density varies within the granulosa cell populations, antral granulosa (aGC; those aspirated by follicular puncture) and membrane associated granulosa (mGC; those scraped from the follicular wall) were compared to thecal cell expression profiles determined by mRNA microarrays. Thecal cell gene expression was less affected in the peri-ovulatory follicle when compared to granulosa cells, as evidenced by only 2% versus 25% of the ~11,000 genes expressed changing in response to the LH surge, respectively. The majority of the 203 LH-regulated thecal genes were also LH regulated in granulosa cells, leaving a total of 58 genes as LH-regulated theca cell specific genes. Most of the 58 genes (i.e., 74%) thecal specific genes including several known thecal markers (CYP17A1, NR5A1) were downregulated, while most genes identified are new to theca. Many of the newly identified upregulated thecal genes (e.g., PTX3, RND3, PPP4R4) were also upregulated in granulosa. Minimal expression differences were observed between aGC and mGC, however, transcripts encoding extracellular proteins (NID2) and matrix modulators (ADAMTS1, SASH1) predominated these differences. We also identified large numbers of unknown LH-regulated granulosa cell genes and discuss their putative roles in ovarian function. The single dominant ovarian follicle was collected from each cow before the LH surge or 22 hours after GnRH (used to induce LH surge). RNA was extracted from three independent cells within each follicle and there were hybridized on Affymetrix microarrays.
Project description:The molecular mechanisms that regulate the pivotal transformation processes observed in the follicular wall following the pre-ovulatory LH-surge, are still not established, particularly for cells of the thecal layer. To elucidate thecal and granulosa cell type-specific biological functions and signaling pathways, large dominant bovine follicles were collected before and 21 hrs after an exogenous GnRH induced LH surge. Because LH receptor density varies within the granulosa cell populations, antral granulosa (aGC; those aspirated by follicular puncture) and membrane associated granulosa (mGC; those scraped from the follicular wall) were compared to thecal cell expression profiles determined by mRNA microarrays. Thecal cell gene expression was less affected in the peri-ovulatory follicle when compared to granulosa cells, as evidenced by only 2% versus 25% of the ~11,000 genes expressed changing in response to the LH surge, respectively. The majority of the 203 LH-regulated thecal genes were also LH regulated in granulosa cells, leaving a total of 58 genes as LH-regulated theca cell specific genes. Most of the 58 genes (i.e., 74%) thecal specific genes including several known thecal markers (CYP17A1, NR5A1) were downregulated, while most genes identified are new to theca. Many of the newly identified upregulated thecal genes (e.g., PTX3, RND3, PPP4R4) were also upregulated in granulosa. Minimal expression differences were observed between aGC and mGC, however, transcripts encoding extracellular proteins (NID2) and matrix modulators (ADAMTS1, SASH1) predominated these differences. We also identified large numbers of unknown LH-regulated granulosa cell genes and discuss their putative roles in ovarian function.
Project description:The LH surge induces panoply of events that are essential for ovulation and corpus luteum formation. The transcriptional responses to the LH surge of pre-ovulatory granulosa cells are complex and still poorly understood. In the present study, a genome wide bovine oligo array was used to determine how the gene expression profiles of granulosa cells are modulated by the LH surge. Granulosa cells from three different statuses were used (1) 2 h before the induction of the LH surge, (2) 6 h and (3) 22 h after the LH surge to assess the short and long term effects of this hormone on follicle differentiation. The results obtained were a list of differentially expressed transcripts for each granulosa cell group. To provide a comprehensive understanding of the processes at play, biological annotations were used to reveal the different functions of transcripts, confirming that the LH surge acts in a temporal manner. The pre-LH group is involved in typical tasks such as cell division, development and proliferation, while the short response of the LH surge included features such as response to stimulus, vascularisation and lipid synthesis, which are indicative of cells preparing for ovulation. The late response of granulosa cells revealed terms associated with protein localization and intra-cellular transport corresponding to the future secretion task that will be required for the transformation of granulosa cells into corpus luteum. Overall, results described in this study provide new insights into the different transcriptional steps that granulosa cells go through during ovulation and before luteinization. Three biological granulosa cells samples: 2 h pre-LH vs. 6 h post-LH vs. 22 h post-LH. Biological replicates: 3 with a technical dye-swap replicates (Dy 547 and Dy 647) for each biological replicate. Hybridizations were performed in a loop design for a total a 9 hybridizations.
Project description:RUNX1 is induced by the LH surge in the ovary and plays an important role in granulosa cells in the peri-ovulatory window through the induction of key gene expression. The ablation of the canonical heterodimer partner of RUNX1 (CBFβ) leads to ovulatory failure and subfertility in female mice. A possible interaction between RUNX1 and PGR on the chromatin level has also been indicated. However, the properties of RUNX1 chromatin binding in granulosa cells in response to the LH surge remains unknown. This study aims to characterise the RUNX1 cistrome in pre- and peri-ovulatory granulosa cells and explore the potential interaction between RUNX1 and the key ovulatory factor PGR.
Project description:The LH surge induces panoply of events that are essential for ovulation and corpus luteum formation. The transcriptional responses to the LH surge of pre-ovulatory granulosa cells are complex and still poorly understood. In the present study, a genome wide bovine oligo array was used to determine how the gene expression profiles of granulosa cells are modulated by the LH surge. Granulosa cells from three different statuses were used (1) 2 h before the induction of the LH surge, (2) 6 h and (3) 22 h after the LH surge to assess the short and long term effects of this hormone on follicle differentiation. The results obtained were a list of differentially expressed transcripts for each granulosa cell group. To provide a comprehensive understanding of the processes at play, biological annotations were used to reveal the different functions of transcripts, confirming that the LH surge acts in a temporal manner. The pre-LH group is involved in typical tasks such as cell division, development and proliferation, while the short response of the LH surge included features such as response to stimulus, vascularisation and lipid synthesis, which are indicative of cells preparing for ovulation. The late response of granulosa cells revealed terms associated with protein localization and intra-cellular transport corresponding to the future secretion task that will be required for the transformation of granulosa cells into corpus luteum. Overall, results described in this study provide new insights into the different transcriptional steps that granulosa cells go through during ovulation and before luteinization.
Project description:Cellular mechanisms that contribute to low estradiol concentrations produced by the preovulatory ovarian follicle in cattle with a compromised metabolic status (such as lactatino) are largely unknown. To gain insight into the main metabolic mechanisms affecting preovulatory follicle function RNAseq profiling was conducted on non-lactating Holstein-Friesian heifers (n=16) and lactating Holstein-Friesian cows (n=17) at three stages of preovulatory follicle development: A) newly selected dominant follicle in the luteal phase (Selection); B) follicular phase before the LH surge (Differentiation) and C) pre-ovulatory phase after the LH surge (Luteinization). Based on a combination of RNA sequencing, ingenuity pathway analysis and Q-RT-PCR validation several important molecular markers involved in steroid biosynthesis, such as the expression of steroidogenic acute regulatory protein (STAR) within developing dominant follicles, were identified to be affected (downregulated) by the catabolic state. We propose that the adverse metabolic environment caused by lactation decreases preovulatory follicle function by affecting cholesterol transport into the mitochondria to initiate steroidogenesis. Granulosa and Theca samples from the dominant follicle were taken from cows and heifers at stages: selection, differentiation and luteinization.
Project description:Coordinated interactions between ovarian granulosa and theca cells are required for female endocrine function and fertility. To elucidate these interactions the regulation of the granulosa and theca cell transcriptomes during bovine antral follicle development were investigated. Granulosa cells and theca cells were isolated from small (<5 mm), medium (5-10 mm), and large (>10 mm) antral bovine follicles. A microarray analysis of 24,000 bovine genes revealed that granulosa cells and theca cells each had gene sets specific to small, medium and large follicle cells. Transcripts regulated (i.e., minimally changed 1.5-fold) during antral follicle development for the granulosa cells involved 446 genes and for theca cells 248 genes. Only 28 regulated genes were common to both granulosa and theca cells. Regulated genes were functionally categorized with a focus on growth factors and cytokines expressed and regulated by the two cell types. Candidate regulatory growth factor proteins mediating both paracrine and autocrine cell-cell interactions include macrophage inflammatory protein (MIP1 beta), teratocarcinoma-derived growth factor 1 (TDGF1), stromal derived growth factor 1 (SDF1; i.e., CXCL12), growth differentiation factor 8 (GDF8), glia maturation factor gamma (GMFG), osteopontin (SPP1), angiopoietin 4 (ANGPT4), and chemokine ligands (CCL 2, 3, 5, and 8). The current study examined granulosa cell and theca cell regulated genes associated with bovine antral follicle development and identified candidate growth factors potentially involved in the regulation of cell-cell interactions required for ovarian function. Experiment Overall Design: Granulosacell RNA samples from three groups of follicles different in size - small, medium, and large (pooled untreated ovaries) are compared between each other. Each group has 2 separate biological replicas; each replica contained pooled RNA from 20-40 ovaries from 6-10 different animals.
Project description:During ovulation, the LH surge leads to the activation of various signalling cascades in granulosa cells, resulting in a critical shift in chromatin landscape and correspondingly the ovarian gene expression profile. Such large-scale genomic reprogramming involves a specific suite of ovulatory transcription factors. This study aims to characterise global changes in the chromatin landscape that are induced by the LH surge in granulosa cells during ovulation.
Project description:High environmental temperatures induce detrimental effects on various reproductive processes in cattle. According to the predicted global warming the number of days with unfavorable ambient temperatures will further increase. The objective of this study was to investigate effects of acute heat stress during the late pre-ovulatory phase on morphological, physiological and molecular parameters of dominant follicles in cycling cows during lactation. Eight German Holstein cows in established lactation were exposed to heat stress (28°C) or thermoneutral conditions (15°C) with pair-feeding for four days. After synchronization growth of dominant follicles was monitored by ultrasonogrphy, and 21 hrs after an induced pre-ovulatory LH surge antral steroid hormones and granulosa cell-specific gene expression profiles were determined. The data showed that the pre-ovulatory growth of dominant follicles and the estradiol, but not the progesterone concentrations tended to be slightly affected. mRNA microarray and hierarchical cluster analysis revealed distinct expression profiles in granulosa cells derived from heat stressed compared to pair-fed animals. Among the 255 affected genes heatstress-, stress- or apoptosis associated genes were not present. But instead, we found up-regulation of genes essentially involved in G-protein coupled signaling pathways, extracellular matrix composition, and several members of the solute carrier family as well as up-regulation of FST encoding follistatin. In summary, the data of the present study show that acute pre-ovulatory heat stress can specifically alter gene expression profiles in granulosa cells, however without inducing stress related genes and pathways and suggestively can impair follicular growth due to affecting the activin-inhibin-follistatin system.
Project description:Granulosa cells from three different stages were used to assess the short- and long-term effects of luteinizing hormone (LH) on follicle differentiation: 1) 2 h before induction of the LH surge, 2) 6 h and 3) 22 h after the LH surge. Three time points experiment: 2h pre-LH, 6h post-LH and 22h post-LH. Granulosa cells from the 6h post-LH and 22h post-LH were compared to the 2h pre-LH. Biological replicates: 4 from each time point. One replicate per array. Dye-swaps were performed.