Effect of maternal age on the granulosa cell transcriptome of preovulatory dominant follicle in cattle
Ontology highlight
ABSTRACT: The objective of the study was to determine how maternal age influences the transcriptome of the dominant follicle during the preovulatory period. We tested the hypotheses that delayed ovulation in aged cows is associated with 1) altered gene expression of granulosa cells of preovulatory follicles (24 h after LH treatment) and 2) decreased synthesis of progesterone by granulosa cells of the preovulatory follicle. Granulosa cells of preovulatory follicles obtained 24 h after LH treatment from aged Hereford cows (19.0 ±2.5 years; n=3) were compared to those from young cows (9.0 ± 0.6 years; n=3) using bovine specific microarrays (EmbryoGENE-EMBV3; GPL13226). Results were confirmed by RT-qPCR. A total of 1340 genes or gene isoforms were expressed differentially (â¥2-fold change; p ⤠0.05) in aged cows vs. young cows (daughters of aged cows). In conclusion, transcriptome analysis of granulosa cells from aged cows revealed a delayed or suboptimal response to the preovulatory LH stimulus, represented by delayed cellular differentiation, luteinization and progesterone synthesis. Granulosa cells of the dominant preovulatory follicle 24 h after LH treatment were compared between aged vs.young cows. Three biological replicates (each composed of one aged and one young cow). 3 Three technical replicate (dye swap). One biological or technical replicate per array.
Project description:The objective was to determine age-associated changes in the transcriptome of granulosa cells recovered from the dominant follicle at the time of selection. Granulosa cells were collected from the dominant follicle of aged and young cows after ovariectomy (15 ±1.5 years, n=3 and 6 ± 1.1 years, n=3), or ultrasound-guided follicle aspiration (16±2.1 years, n=4 and 7±1.2 years, 6 ± 1.1 years, n=4) 3-days after ovulation (Day 0). Messenger-RNA was extracted, amplified, labeled with florescent dyes, and hybridized with bovine-specific microarrays (GEO accession # GPL13226). Target intensities were analyzed to determine differential gene expression in granulosa cells from aged vs. young cows. A total 169 genes were differentially expressed (⥠2 fold-change; Pâ¤0.05) between age groups. In conclusion, granulosa cells collected at the time of selection of the dominant follicle exhibited age-related changes in the transcriptome that may explain follicle-associated loss of oocyte competence in aged cows. Granulosa cells of the dominant follicle at the time of selection (aged vs.young cows). Three biological replicates (each composed of one aged and one young cow). 3 Three technical replicate (dye swap). One biological or technical replicate per array.
Project description:The objective of the study was to determine how maternal age influences the transcriptome of the dominant follicle during the preovulatory period. We tested the hypotheses that delayed ovulation in aged cows is associated with 1) altered gene expression of granulosa cells of preovulatory follicles (24 h after LH treatment) and 2) decreased synthesis of progesterone by granulosa cells of the preovulatory follicle. Granulosa cells of preovulatory follicles obtained 24 h after LH treatment from aged Hereford cows (19.0 ±2.5 years; n=3) were compared to those from young cows (9.0 ± 0.6 years; n=3) using bovine specific microarrays (EmbryoGENE-EMBV3; GPL13226). Results were confirmed by RT-qPCR. A total of 1340 genes or gene isoforms were expressed differentially (≥2-fold change; p ≤ 0.05) in aged cows vs. young cows (daughters of aged cows). In conclusion, transcriptome analysis of granulosa cells from aged cows revealed a delayed or suboptimal response to the preovulatory LH stimulus, represented by delayed cellular differentiation, luteinization and progesterone synthesis.
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:Gonadotropin surge acts on the preovulatory follicle of the ovary to induce luteinization of follicular cells, oocyte meiotic maturation, cumulus expansion and follicular rupture leading to ovulation. These processes are brought about by spatial and temporal changes in transcriptional regulation of genes in the follicular cells in response to the gonadotropin surge. Analysis of gene expression changes in the periovulatory follicular cells will help in delineating the signal transduction pathways involved in the above mentioned processes. In monoovulatory species like bovines, the time interval of 24-28 hours between gonadotropin surge and ovulation provides distinct advantage for studying the temporal changes in the gene expression pattern. Thus, in the present study, we attempt to identify the temporal changes in the global gene expression profile in the periovulatory follicle of buffalo cows in response to gonadotropin surge and the results suggest the involvement of Insulin-like Growth Factor 1 and cytokine signaling pathways in the periovulatory events. Experiment Overall Design: To study the periovulatory gene expression changes in buffalo cows, an induced-ovulation model system involving sequential treatment with PGF2alpha and GnRH was standardized. The follicular wave containing at least one large follicle of ~7mm size was determined by ultrasonography on day 7 of the estrous cycle before administering exogenous PGF2alpha to induce luteolysis and follicular growth. Exogenous GnRH (100µg i.m) was administered 36h post PGF2alpha to induce LH surge. The time course of increase in LH levels post GnRH injection was monitored. Since peak LH levels are attained 2 h post GnRH administration, the time intervals of 3 h post GnRH (corresponding to1 h post LH surge) and 24 h post GnRH (corresponding to 22 h post LH surge) were chosen to identify the gene expression profile associated with immediate early and delayed changes in periovulatory follicle respectively. Thus ovaries were collected before, 1 h and 22 h post LH surge and follicle wall and granulosa cells were isolated from the ovaries and snap frozen for the purpose of RNA isolation.
Project description:Determining the spatial and temporal expression of genes involved in the ovulatory pathway is critical for the understanding of the role of each estrogen receptor in the modulation of folliculogenesis and ovulation. Estrogen receptor (ER) b is highly expressed in ovarian granulosa cells and mice lacking ERb (bERKO) are subfertile due to inefficient ovulation. Previous work has focused on isolated granulosa cells or cultured follicles and while informative, provides confounding results due to the heterogeneous cell types present including granulosa, theca and oocytes and exposure to in vitro conditions. Herein, we isolated preovulatory granulosa cells from WT and ERb-null mice using laser capture microdissection to examine the genomic transcriptional response downstream of PMSG (mimicking FSH) and PMSG/hCG (mimicking LH) stimulation. This allows for a direct comparison of in vivo granulosa cells at the same stage of development from both WT and ERb-null ovaries. ERb-null granulosa cells showed altered expression of genes known to be regulated by FSH (Akap12 and Runx2) as well as not previously reported (Arnt2 and Pou5f1) in WT granulosa cells. Our analysis also identified 304 genes not previously associated with ERb in granulosa cells. LH responsive genes including Abcb1b and Fam110c show reduced expression in ERb-null granulosa cells; however novel genes including Rassf2 and Megf10 were also identified as being downstream of LH signaling in granulosa cells. Collectively, our data suggests that granulosa cells from ERb-null ovaries may not be appropriately differentiated and are unable to respond properly to gonadotropin stimulation We used microarray to compare the gene expression profiles of wiltype (WT) and Erb-null (bERKO) preovulatory granulosa cells as they respond to either PMSG or PMSG+hCG treatments. Laser microdissection was used to collect a purified population of granulosa cells only from preovulatory follicles. We chose to compre the response to PMSG or PMSG+hCG of granulosa cells collected from either WT and bERKO preovulatory follicles. We chose to collect cells 48h after mice were treated with PMSG to compare the gene expression profile ot preovulatory granulosa cells. We also studied the response of these cells to LH (or hCG) as we collected cells 4h after mice were treated with hCG (peak of transcriptional response to hCG).
Project description:The fertility of dairy cows is challenged during early lactation and better nutritional strategies need to be developed to address this issue. Combined supplementation of folic acid and vitamin B12 improves energy metabolism in the dairy cow during early lactation. Therefore, the present study was undertaken to explore the effects of this supplement on gene expression in granulosa cells from the dominant follicle during the postpartum period. Multiparous Holstein cows received weekly intramuscular injection of 320 mg folic acid and 10 mg vitamin B12 (treated group) beginning 24 (SD 4) d before calving until 56 d after calving, whereas the control group received saline. The urea plasma concentration was significantly decreased during the pre-calving period, and the concentration of both folate and vitamin B12 were increased in treated animals. Milk production and dry matter intake were not significantly different between the two groups. Plasma concentrations of folates and vitamin B12 were increased in vitamin-treated animals. Daily dry matter intake was not significantly different between the 2 groups before (13.5 kg SE 0.5) and after (23.6 kg SE 0.9) calving. Average energy-corrected milk tended to be greater in vitamin-treated cows, 39.7 (SE 1.4) and 38.1 (SE 1.3) kg/d for treated and control cows, respectively. After calving, average plasma concentration of BHBA tended to be lower in cows injected with the vitamin supplement, 0.47 (SE 0.04) vs. 0.55 (SE 0.03) for treated and control cows, respectively. The ovarian follicle ? 12 mm in diameter was collected by ovarian pick-up after estrus synchronization. Recovered follicular fluid volumes were greater in the vitamin-treated group. A microarray platform was used to investigate the impact of treatment on gene expression of granulosa cells. Lower expression of genes involved in the cell cycle and higher expression of genes associated with granulosa cell differentiation prior to ovulation were observed. Selected candidate genes were analyzed by reverse transcription quantitative polymerase chain reaction. Although the effects of intramuscular injections of folic acid and vitamin B12 on lactational performance and metabolic status of animals were limited, Ingenuity Pathway Analysis of gene expression in granulosa cells suggests a stimulation of cell differentiation in vitamin-treated cows, which may be the result of an increase in LH secretion. Two conditions experiment (Control and Treated). Granulosa cells from the 66h post second PGF2alpha injection. Biological replicates: 3 from each time point. Two technical replicates for each comparison (dye-swap).
Project description:A surge of luteinizing hormone (LH) from the pituitary gland triggers ovulation, oocyte maturation, and luteinization for successful reproduction in mammals. Since the signaling molecules RAS and ERK1/2 are activated by a LH surge in granulosa cells of preovulatory follicles, we disrupted Erk1/2 in mouse granulosa cells and provide in vivo evidence that these kinases are necessary for LH-induced oocyte resumption of meiosis, ovulation, and luteinization. In addition, biochemical analyses and selected disruption of the Cebpb gene in granulosa cells demonstrate that C/EBP is a critical downstream mediator of ERK1/2 activation. These mouse models provide in vivo systems in which to define the context specific and molecular mechanisms by which granulosa cells respond to LH and these mechanisms are relevant to the regulation of human fertility and infertility.
Project description:Cows in Negative Energy Balance (NEB) may preferentially divert nutrients away from reproduction, thereby experiencing a period of anovulatory anestrus, delayed ovulation of large follicles and a condition of impaired fertility. To better understand the changes occurring in these large follicles as a function of time post-partum granulosa cells of preovulatory follicles have been collected at different times: 30, 60, 90 and 120 days after calving . An analysis of the transcriptome was performed using a global bovine oligo-array microarray to map the differences in genes expression and cellular functions that occur in the follicular microenvironment during the progressive recovery from NEB condition in dairy cow Four time points experiment: 30, 60, 90 and 120 days. Granulosa cells from the 30, 60 and 90 days compare to the 120 days (reference). Biological replicates: 3 from each time point. One replicate per array.
Project description:A surge of luteinizing hormone (LH) from the pituitary gland triggers ovulation, oocyte maturation, and luteinization for successful reproduction in mammals. Since the signaling molecules RAS and ERK1/2 are activated by a LH surge in granulosa cells of preovulatory follicles, we disrupted Erk1/2 in mouse granulosa cells and provide in vivo evidence that these kinases are necessary for LH-induced oocyte resumption of meiosis, ovulation, and luteinization. In addition, biochemical analyses and selected disruption of the Cebpb gene in granulosa cells demonstrate that C/EBP is a critical downstream mediator of ERK1/2 activation. These mouse models provide in vivo systems in which to define the context specific and molecular mechanisms by which granulosa cells respond to LH and these mechanisms are relevant to the regulation of human fertility and infertility. Immature wild type or ERK1/2 conditonal knock-out mice were injected with 5IU equine chorionic gonadotropin (eCG)-48h followed by 5 IU hCG injection. The ovarian granulosa cells were collected at hCG 0h, 2.5h, or 4h and the gene expression pforiles were compared by microarray method.
Project description:Transcriptional profiling of cows granulosa cells comparing granulosa cells from superstimulated control cows with granulosa cells from superstimulated cetrotide treated cows. Abstract:In cow, follicular growth stimulation (FSH) followed by a 44h-68h coasting (no FSH) period has been shown to be beneficial for developmental competence of aspirated oocytes. This process has been optimized but the associated physiology is not perfectly understood. During the above treatment LH pulse frequency is basal as the animal are in the luteal phase. The goal of this study was to test the existence of a beneficial effect of basal LH pulses during competence acquisition. To answer to this question, LH pulses have been pharmacologically inhibited during the optimal coasting period with GnRH antagonists. Commercial milking cycling cows (n=5) were stimulated with 3 days of FSH followed by a coasting period of 68H, with and without cetrorelix injections. At the scheduled time, transvaginal aspirations of immature oocytes were performed, followed by IVF while follicular cells were pooled for each animal and were snap-frozen. Granulosa cells RNA was extracted amplified and hybridized on Embryogene bovine microarray slides. Data were normalized with Loess, and analyzed with Limma procedure. Follicle size group proportions and granulosa cell transcriptome were studied. (1) There was a significant reduction in >10mm diameter follicles with cetrorelix comparing to without treatment. (2) Transcriptome analysis reveals 724 tanscripts potentially regulated by basal gonadotropins before LH surge. Among this LH influenced gene group, 84 transcripts were positively associated to developmental competence. This work allows the identification of subpopulations of gene signals dependant from LH or not, and permits a better comprehension of the implication of basal LH in follicle growth and in competence acquisition process.