RNA‐sequencing reveals genes linked with oocyte developmental potential in bovine cumulus cells
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ABSTRACT: Cumulus cells provide an interesting biological material to perform analyses to understand the molecular clues determining oocyte competence. The objective of this study was to analyze the transcriptional differences between cumulus cells from oocytes exhibiting different developmental potentials following individual in vitro embryo production by RNA‐seq. Cumulus cells were allocated into three groups according to the developmental potential of the oocyte following fertilization: (1) oocytes developing to blastocysts (Bl+), (2) oocytes cleaving but arresting development before the blastocyst stage (Bl-), and (3) oocytes not cleaving (Cl-).
Project description:Is the transcriptome of cumulus cells a good predictor of the embryo’s developmental competence? The objective of this study was to analyze the transcriptional differences between cumulus cells from oocytes exhibiting different developmental potentials following individual in vitro embryo production and transfer by RNA‐seq. Cumulus cells were allocated into three groups according to the developmental potential of their enclosed oocyte: (1) not able to develop to the blastocyst stage (Bl–), (2) able to develop to the blastocyst stage but failing to establish a pregnancy (P–), or (3) able to develop to the blastocyst stage and to establish a clinical pregnancy (P+).
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
Project description:The oocyte forms a complex with their somatic cumulus cells within the follicle throughout the preovulatory maturation steps. Cumulus cells support their oocyte not only through mechanical protection but also with a close bidirectional exchange of metabolites. Analysis of the oocytes cumulus gives the opportunity to explore non-invasively oocytal well-being and quality. In vitro maturation (IVM) is the first rate-limiting step in in vitro embryo production. Analysis of protein expression in cumulus cells around this critical step helps to explore the impact of maturation conditions and to examine an influence on maturational competence of the oocyte. The goal of this study was the comparison of the cumulus proteome of oocytes with and without maturational competence matured under in vivo and in vitro conditions. Therefore twenty cumulus samples corresponding to single oocytes were analysed. Half of the samples were matured in vivo and the other half in vitro. For each maturation group, cumulus from oocytes matured successfully (SM; n=5) and failed to mature (FM; n=5) were analysed.
Project description:Cumulus cells surrounding the oocyte were sampled at the following stages: developmentally incompetent or poorly competent prophase I oocytes (NC1 oocytes), developmentally competent prophase I oocytes (C1 oocytes), and developmentally competent metaphase II oocytes (C2 oocytes). NC1 samples were collected from immature, unexpanded cumulus-oocytes complexes (COC) from prepubertal (3-week-old) mice, C1 samples from immature, unexpanded cumulus-oocytes complexes (COC) from adult (8-week-old) and C2 samples from mature, expanded COCs obtained from the oviduct from 8-week-old mice after standard superovulation protocol. Global transcriptional profiling was performed using cumulus cells collected from murine ovarian follicles during in vivo oocyte developmental competence acquisition. Cumulus cells were collected at 3 stages: early stage follicles (prophase I arrested oocytes, meiotically competent but developmentally incompetent, n=5), late stage follicles (prophase I arrested oocytes, meiotically competent and developmentally competent, n=5) and ovulatory follicles collected in vivo (metaphase II arrested oocytes, developmentally fully competent, n=5).
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 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. Total RNA from pools of cumulus cells (n = 4) collected from adult and prepubertal animals for microarray experiments was amplified. Two color microarray experiments were conducted using a bovine cDNA array containing expressed sequence tags (ESTs) representing approximately 15200 unique genes. Hybridizations were performed on duplicate slides (prepubertal versus adult) and incorporated a dye swap. The total number of slides used is eight.
Project description:Somatic cells surrounding the oocyte were sampled at the following stages: developmentally incompetent or poorly competent prophase I oocytes (NC1 oocytes), developmentally competent prophase I oocytes (C1 oocytes), and developmentally competent metaphase II oocytes (C2 oocytes). NC1 cumulus cells (CC) were sampled from immature calf oocytes, C1 samples from immature cow oocytes, and C2 samples from in vivo matured cow oocytes. Global transcriptional profiling was performed using cumulus cells collected from bovine ovarian follicles during in vivo oocyte developmental competence acquisition. Cumulus cells were collected at 3 stages: early stage follicles (prophase I arrested oocytes, meiotically competent but developmentally incompetent, n=6), late stage follicles (prophase I arrested oocytes, meiotically competent and developmentally competent, n=6) and ovulatory follicles collected by ovum pick-up (OPU) in vivo (metaphase II arrested oocytes, developmentally fully competent, n=5).
Project description:Cytoplasmic and nuclear maturation of oocytes as well as interaction with the surrounding cumulus cells are important features relevant to the acquisition of developmental competence. We used brilliant cresyl blue (BCB) to distinguish oocytes with low activity of the enzyme Glucose-6-Phosphate Dehydrogenase, and thus separated fully grown (BCB+) oocytes from those in the growing phase (BCB-). The BCB+ oocytes are twice as likely to produce a blastocyst in vitro compared to BCB- oocytes (P<0.01). We analyzed mitochondrial DNA (mtDNA) copy number in single oocytes and determined that BCB- oocytes have 1.3-fold more copies than BCB+ oocytes (P=0.004). We also interrogated the transcriptome of oocytes and surrounding cumulus cells of BCB+ versus BCB- oocytes. There was no differential transcript abundance of genes expressed in oocytes, but we identified 172 genes in cumulus cells with differential transcript abundance (FDR<0.05) based on the BCB staining of their oocyte. Differential gene co-expression analysis between BCB+ and BCB- oocytes and their surrounding cumulus cells revealed dynamic coordination of transcript abundance between both compartments of the cumulus-oocyte complex. We identified a subset of genes whose co-expression in fully grown oocytes (n=75) and their surrounding cumulus cells (n=108) compose a unique profile of the cumulus-oocyte complex. In conclusion, as oocytes transition from growing to fully grown, there is an increase in the likelihood of producing a blastocyst, a reduction of mtDNA copies and no systematic variation of transcript abundance. Cumulus cells present changes in transcript abundance, which reflects in a dynamic co-expression between oocyte and cumulus cells.
Project description:Cumulus cells surrounding the oocyte were sampled at the following stages: developmentally incompetent or poorly competent prophase I oocytes (NC1 oocytes), developmentally competent prophase I oocytes (C1 oocytes), and developmentally competent metaphase II oocytes (C2 oocytes). NC1 samples were collected from immature, unexpanded cumulus-oocytes complexes (COC) from prepubertal (3-week-old) mice, C1 samples from immature, unexpanded cumulus-oocytes complexes (COC) from adult (8-week-old) and C2 samples from mature, expanded COCs obtained from the oviduct from 8-week-old mice after standard superovulation protocol.
Project description:Cumulus cells, surrounding the oocyte, play a key role in the acquisition of oocyte competence to be fertilized and to sustain early embryo development. Cumulus cells contribute to oocyte development by metabolizing energy substrates such as glutathione that may protect the oocyte from oxidative stress damages. The aim of our study was to compare transcriptomics profiles of cumulus enclosed (CEO) and cumulus denuded (CDO) oocytes after in vitro maturation. Global transcriptional profiling was performed using cumulus enclosed and cumulus denuded oocytes after in vitro maturation. Matured oocytes were obtained after 22h of maturation with (CEO) or without (CDO) cumulus cells and four replicates of 25 oocytes were collected for RNA extraction. Gene expression analysis was performed by comparing CDO versus CEO oocytes that represents a total of 8 slides using a dye swap hybridisation protocol.
Project description:Cumulus cells are biologically distinct from other follicular cells and perform specialized roles, transmitting signals within the ovary and supporting oocyte maturation during follicular development. The bi-directional communication between the oocyte and the surrounding cumulus cells is crucial for the acquisition of oocyte competence. Using Illumina/deep-sequencing technology, we dissected the small RNAome of pooled human mature MII oocytes and cumulus cells. Cumulus cells and MII mature oocytes small RNA profiles were generated by deep-sequencing, using Illumina 1G sequencer