Effect of ovarian stimulation on oocyte gene expression in cow
Ontology highlight
ABSTRACT: The objective of the study was to analyze the impact of FSH on transcriptome changes of in vivo bovine oocytes. Oocytes were collected from naturally ovulated and superovulated animals at 2 hours pre-LH surge, 6 hours post-LH surge, and 22 hours post-LH surge. Six-condition experiment. Biological replicates: 1 . Technical replicate:2.
Project description:The objective of the study was to analyze the impact of FSH on transcriptome changes of in vivo bovine oocytes. Oocytes were collected from naturally ovulated and superovulated animals at 2 hours pre-LH surge, 6 hours post-LH surge, and 22 hours post-LH surge.
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:It is known that granulosa cells (GCs) mediate gonadotropin-induced oocyte meiosis resumption by releasing EGF-like factors in mammal, however, the detail molecular mechanisms remain unclear. Here, we demonstrate that luteinizing hormone (LH) surge induced histone deacetylase 3 (HDAC3) downregulation in GCs is essential for oocyte maturation. Before the LH surge, HDAC3 is highly expressed in GCs. Transcription factors, such as FOXO1, mediates recruitment of HDAC3 to the amphiregulin (Areg) promoter, which suppresses AREG expression. With the LH surge, decreased HDAC3 in GCs enables histone H3K14 acetylation and binding of the SP1 transcription factor to the Areg promoter to initiate AREG transcription and oocyte maturation. Conditional knockout of Hdac3 in granulosa cells in vivo or inhibition of HDAC3 activity in vitro promotes the maturation of oocytes independent of LH. Taking together, HDAC3 in GCs within ovarian follicles acts as a negative regulator of EGF-like growth factor expression before the LH surge.
Project description:It is known that granulosa cells (GCs) mediate gonadotropin-induced oocyte meiosis resumption by releasing EGF-like factors in mammal, however, the detail molecular mechanisms remain unclear. Here, we demonstrate that luteinizing hormone (LH) surge induced histone deacetylase 3 (HDAC3) downregulation in GCs is essential for oocyte maturation. Before the LH surge, HDAC3 is highly expressed in GCs. Transcription factors, such as FOXO1, mediates recruitment of HDAC3 to the amphiregulin (Areg) promoter, which suppresses AREG expression. With the LH surge, decreased HDAC3 in GCs enables histone H3K14 acetylation and binding of the SP1 transcription factor to the Areg promoter to initiate AREG transcription and oocyte maturation. Conditional knockout of Hdac3 in granulosa cells in vivo or inhibition of HDAC3 activity in vitro promotes the maturation of oocytes independent of LH. Taking together, HDAC3 in GCs within ovarian follicles acts as a negative regulator of EGF-like growth factor expression before the LH surge.
Project description:It is known that granulosa cells (GCs) mediate gonadotropin-induced oocyte meiosis resumption by releasing EGF-like factors in mammal, however, the detail molecular mechanisms remain unclear. Here, we demonstrate that luteinizing hormone (LH) surge induced histone deacetylase 3 (HDAC3) downregulation in GCs is essential for oocyte maturation. Before the LH surge, HDAC3 is highly expressed in GCs. Transcription factors, such as FOXO1, mediates recruitment of HDAC3 to the amphiregulin (Areg) promoter, which suppresses AREG expression. With the LH surge, decreased HDAC3 in GCs enables histone H3K14 acetylation and binding of the SP1 transcription factor to the Areg promoter to initiate AREG transcription and oocyte maturation. Conditional knockout of Hdac3 in granulosa cells in vivo or inhibition of HDAC3 activity in vitro promotes the maturation of oocytes independent of LH. Taking together, HDAC3 in GCs within ovarian follicles acts as a negative regulator of EGF-like growth factor expression before the LH surge.
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.
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: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: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.
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.