Project description:Oocyte-derived paracrine factors and estrogens cooperate to regulate the function and development of mouse cumulus cells. Cumulus oocyte complexes (COCs) were isolated from ovaries of mice. Oocytes were removed from some complexes (OOX). Groups were cultured with/without oocytes with/without estrogen and then cumulus cell transcriptome analyzed by microarrays.
Project description:Transcriptomes of mouse mural granulosa cells were sequenced to identify transcripts expressed in mural granulosa cells of ovaries. Moreover, transcriptomes of cumulus cells were compared between those of young (2 month-old) and old mice (10 month-old) to assess the effects of ageing on cumulus cells. In addition, transcriptomes of cumulus-oocyte complexes were compared between DBA/2 and (C57BL/6 x DBA/2)F1 mice to assess the strain differences.
Project description:Cumulus-oocyte complexes were isolated at seperate time-points to generate temporal complexes. Targets from two biological replicates at each time point (0h, 8h, 16h post-hCG treatment) were generated and the expression profiles were determined using Affymetrix GeneChip Mouse Genome 430 2.0 Arrays. Comparisons between the sample groups allow the identification of genes with temporal expression patterns. Experiment Overall Design: 2 eCG-primed (48h) pooled cumulus-oocyte complexes, 2 eCG-primed (48h) hCG-treated (8h) pooled cumulus-oocyte complexes, and 2 eCG-primed (48h) hCG-treated (16h) pooled cumulus-oocyte complexes replicates were analyzed
Project description:Ovulation requires sequential molecular events and structural remodeling in the ovarian follicle for the successful release of a mature oocyte capable of being fertilised. Critical to this process is progesterone receptor (PGR), a transcription factor highly yet transiently expressed in granulosa cells of preovulatory follicles. Progesterone receptor knockout (PRKO) mice are anovulatory, with a specific and complete defect in follicle rupture. Therefore, this model was used to examine the critical molecular and biochemical mechanisms necessary for successful ovulation. Although PGR is not expressed in the cumulus cells or oocyte of the preovulatory cumulus oocyte complex (COC), it is well known that the COC responds to the cascade of gene expression changes that occurs in preovulatory granulosa cells. We used microarrays to identify putative ‘ovulation’ genes in preovulatory COCs at a time when PGR expression is maximal in granulosa cells (eCG + 8h hCG) and the preovulatory COC and follicle are undergoing the final changes necessary for successful ovulation.
Project description:Progesterone (P4) is predicted to act as a negative regulatory hormone for oocyte maturation events; however, its local effects during follicular development remain poorly understood in bovine. The complex process of oocyte meiosis progression is dependent on cellular communication among follicular cells. Besides, the breakdown of this communication, mainly between cumulus cells and oocyte, through the retraction of cumulus projections connecting these cells can impact oocyte maturation. In our study, we observed that ipsilateral follicles containing high intrafollicular P4 concentrations enhance the expression of proteins in follicular small extracellular vesicles predicted to be involved in the retraction of membrane projections based on actin filaments, such transzonal projections (TZPs). Additionally, we found that contralateral follicles containing low intrafollicular P4 concentrations are predicted to regulate cellular communication pathways inducing the maintenance of membrane projections in cumulus cells. Our functional analysis confirmed that supplementation of cumulus-oocyte complexes during in vitro maturation with P4 at concentration similar to ipsilateral follicles reduces the number of TZPs. In summary, our study underscores a direct association between P4 concentration and cumulus-oocyte interaction, with potential consequences for the acquisition of oocyte competence.
Project description:The present study was undertaken to discover molecular markers in bovine cumulus cells predictive of oocyte competence and elucidate their functional significance. Differences in RNA transcript abundance in cumulus cells harvested from oocytes of adult versus prepubertal animals (model of poor oocyte quality) were identified by microarray analysis. Four genes of interest encoding for the lysosomal cysteine proteinases cathepsin B, S, K and Z and displaying greater transcript abundance in cumulus cells surrounding oocytes harvested from prepubertal animals were chosen for further investigation. Greater mRNA abundance for such genes in cumulus cells of prepubertal oocytes was confirmed by real time RT-PCR. Elevated transcript abundance for cathepsins B, S and Z was also observed in cumulus cells surrounding adult metaphase II oocytes that developed to the blastocyst stage at a low percentage following parthenogenetic activation, versus those that developed at a high percentage. Functional significance of cumulus cell cathepsin expression to oocyte competence was confirmed by treatment of cumulus oocyte complexes during in vitro oocyte maturation with a cell permeable cysteine proteinase (cathepsin) inhibitor. Inhibitor treatment decreased apoptotic nuclei in the cumulus layer and enhanced development of parthenogenetically activated and in vitro fertilized adult oocytes to the blastocyst stage. Stimulatory effects of inhibitor treatment during meiotic maturation on subsequent embryonic development were not observed when oocytes were matured in the absence of cumulus cells. Results support a functional role for cumulus cell cathepsins in compromised oocyte competence and suggest that cumulus cell cathepsin mRNA abundance may be predictive of oocyte quality. Keywords: Bovine, microarray, cDNA, cumulus cells