Project description:Purpose: Preovualtory follicle diameter influences embryo quality in beef cattle that rely on a gonadotropin releasing hormone (GnRH) injection to induce the preovualtory gonadotropin surge and subsequent ovualtion. The goals of this study are to compare transcriptome profiles of pools of four oocytes or associated cumulus cells collected from small (≤11.7mm) and large follicles (≥12.7 mm) exposed to a GnRH-induced gonadotropin surge and follicles (11.7-14.0 mm) exposed to an endogenous gonadotropin surge (spontaneous follicles). Methods: Oocyte and cumulus cell mRNA profiles of pools of four oocytes or associated cumulus cells collected from small (≤11.7mm) and large follicles (≥12.7 mm) exposed to a GnRH-induced gonadotropin surge or spontaneous follicles (11.7-14.0 mm) which were exposed to an endogenous gonadotropin surge were generated by deep sequencing (n=6 small follicle oocyte, 6 small follicle cumulus, 6 large follicle oocyte, 6 large follicle cumulus, 4 spontaneous follcile oocyte, and 5 spontaneous follicle cumulus pools), using Illumina HiSeq 2000 . The sequence reads that passed quality filters were aligned to the Bos taurus reference genome UMD3.1 using Hisat2mapper. FeatureCounts was used to quantify transcript abundance in each library using Bos taurus gene annotation from Ensembl. Differences in gene transcript expression were then analyzed amoung oocyte or cumulus cell follcile classifications using the packages edgeR and DESeq2 in R software. Results: We mapped an average of 30 million sequence reads per sample to the Bos taurus reference genome UMD3.1 and identified 69, 94, and 83 differentially expressed gene transcripts (DEG) among oocyte libraries from small versus large, small versus spontaneous, and large versus spontaneous follicle classifications, respectively. We also identified 128, 98, and 80 DEG among cumulus cell libraries from small versus large, small versus spontaneous, and large versus spontaneous follicles, respectively. Conclusions: Our study represents detailed analysis of RNA-sequencing data generated from in vivo produced cumulus and oocyte samples collected from preovualtory follicles of varied physiological status after exposure to an endogenous or exogenously stimulated gonadotropin surge. The results of our study highlight key differences in the transcriptome of samples from small, large, or spontaneous follicles and provide insight into the reduced embryo quality observed when small follicles undergo a GnRH induced gonadotropin surge.

Project description:In mammals, the capacity of the female germ cell, the oocyte, to develop into embryo is acquired throughout meiotic maturation. Immature oocyte cannot be fertilized while mature oocyte is apt to accept spermatozoa and to develop an embryo. In a follicle, the oocyte is surrounded by mural granulosa cells (GC) and is physically and metabolically coupled with specialized granulosa cumulus cells (CC) which play an important role in oocyte maturation and fertilization. Factors expressing in GC and CC during maturation may reflect the oocyte quality, i.e. its capacity to be fertilized and assure early embryo development. However, the modifications of the content and the amount of peptide/proteins in the oocyte and the surrounding CC during oocyte maturation are mostly unknown and so there is not an accurate way of evaluating/monitoring how different in vitro maturation (IVM) protocols being in use in assisted reproduction technologies, can affect the process. In this context, Intact Cell MALDI-TOF Mass Spectrometry (ICM-MS) was applied to bovine follicular cells (bovine single oocytes, cumulus cells and granulosa cells) in order to characterize proteomic changes that occur in the follicle during female gamete development. In order to characterize finely endogenous molecular species observed on ICM-MS profiles and to identify markers of interest with their post-translational modifications, we carried out top-down proteomic on the different follicular cells from oocyte, oocyte-cumulus complexes, cumulus cells and granulosa cells protein extracts. Prior to top-down MS using a dual linear ion trap Fourier Transform Mass Spectrometer LTQ Orbitrap Velos, depending on the amount of available biological material, we employed three analytic strategies as a direct infusion, a mono-dimensional liquid chromatography (µLC-1D-MS/MS) and an off-line multi-dimensional liquid chromatography combining four fractionations (based on reverse phase or gel filtration LC) to µLC-MS/MS. Here, we deposited our dataset from µLC-1D-MS/MS (analyses of oocytes, oocyte-cumulus complexes, cumulus cells and granulosa cells protein extracts) and MDLC-MS/MS (analyses of granulosa cells protein extract).

Project description:Background: The gonadotropin-induced resumption of oocyte meiosis in preovulatory follicles is preceded by expression of epidermal growth factor (EGF)-like peptides, amphiregulin (AREG) and epiregulin (EREG), in mural granulosa and cumulus cells. Both the gonadotropins and the EGF-like peptides possess the capacity to stimulate resumption of oocyte meiosis in vitro via activation of a broad signaling network in cumulus cells. To better understand the rapid genomic actions of gonadotropins (FSH) and EGF-like peptides, we analyzed transcriptomes of cumulus cells at 3 h after their stimulation. Methods: We hybridized aRNA from cumulus cells to a pig oligonucleotide microarray and compared the transcriptomes of FSH- and AREG/EREG-stimulated cumulus cells with untreated control cells and vice versa. The identified over- and underexpressed genes were subjected to functional genomic analysis according to their molecular and cellular functions. The expression pattern of 50 selected genes with a known or potential function in ovarian development was verified by real-time qRT-PCR. Results: Both FSH and AREG/EREG increased the expression of genes associated with regulation of cell proliferation, cell migration, blood coagulation and extracellular matrix remodeling. FSH alone induced the expression of genes involved in inflammatory response and in the response to reactive oxygen species. Moreover, FSH stimulated the expression of genes closely related to some ovulatory events either exclusively or significantly more than AREG/EREG (AREG, ADAMTS1, HAS2, TNFAIP6, PLAUR, PLAT, and HSD17B7). In contrast to AREG/EREG, FSH also increased the expression of genes coding for key transcription factors (CEBPB, FOS, ID1/3, and NR5A2), which may contribute to the differing expression profiles of FSH- and AREG/EREG-treated cumulus cells. Conclusions: The impact of FSH on cumulus cell gene transcription was higher than the impact of EGF-like factors in terms of the number of cell functions affected as well as the number of over- and underexpressed genes. Both FSH and EGF-like factors overexpressed genes involved in the post-ovulatory switch in steroidogenesis and tissue remodelling. However, FSH was remarkably more efficient in the up-regulation of several specific genes essential for ovulation of matured oocytes and also genes that been reported to play an important role in maturation of cumulus-enclosed oocytes in vitro.

Project description:Direct exposure to physiologically-relevant elevated temperatures during the first half of in vitro maturation heightens cumulus-derived progesterone production, suppresses matrix metallopeptidase 9 secretion, and alters cumulus transcriptome. We hypothesized that heat-induced perturbations in cumulus cells enveloping maturing oocyte may extend to the mural granulosa of the periovulatory follicle in the heat-stressed cow to subsequently follicular fluid proteome. Lactating Holsteins were pharmacologically stimulated to produce a dominant follicle then given GnRH to induce an LH surge. Following GnRH administration, cows were maintained at ~67 temperature humidity index (THI; thermoneutral conditions) or exposed to conditions simulating an acute heat stress event (71 to 86 THI; heat stress for ~12 h). Fluid was aspirated from periovulatory follicle ~16 h after GnRH. Follicular fluid proteome from thermoneutral (n = 5) and hyperthermic (n = 5) cows was evaluated by quantitative tandem mass spectrometry (nano LC-MS/MS). We identified 35 differentially-abundant proteins. Functional annotation revealed numerous immune-related proteins. Subsequent efforts revealed an increase in levels of the proinflammatory mediator bradykinin in follicular fluid (P = 0.0456) but not in serum (P = 0.9319) of hyperthermic cows. Intrafollicular increases in transferrin (negative acute phase protein) in hyperthermic cows (P = 0.0181) coincided with a tendency for levels to be increased in the circulation (P = 0.0683). Nine out of 15 cytokines evaluated were detected in follicular fluid. Heat stress increased intrafollicular IL6 levels (P = 0.0160). Whether hyperthermia-induced changes in the heat-stressed cow’s follicular fluid milieu reflect changes in mural granulosa, cumulus, other cell types secretions, and/or transudative changes from circulation remains unclear. Regardless of origin, heat stress/hyperthermia related changes in the follicular fluid milieu may have an impact on components important for ovulation and competence of the cumulus-oocyte complex contained within the periovulatory follicle

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