EPAB is required for expression of cumulus cell markers of oocyte and embryo viability

Abstract

ObjectiveSeveral cumulus cell transcripts have been identified as potential non-invasive biomarkers of human embryo development and implantation. Embryonic poly(A) binding protein (EPAB) is expressed exclusively in Xenopus and mouse oocytes and early embryos, and is required for oocyte maturation. Importantly, although EPAB is not expressed in cumulus cells, cumulus expansion and ovulation are also impaired in Epab-/- mice. We therefore asked whether the oocyte-specific EPAB is required for the optimal expression of cumulus cell-biomarkers of embryo viability.DesignExperimental study.Materials and MethodsCumulus cells were collected from Epab-/- and Epab+/+ mice 4 hours after hCG injection and three pooled samples were generated for each group. Microarrays were performed for each of the six samples using Affymetrix GeneChip Mouse Gene 1.0 ST Array platform. Probe level expression values were extracted and background adjustment, inter-array quantile normalization and probe set summarization were performed according to the Robust Multi-Chip Average algorithm.Results663 genes were up-regulated and 1205 genes were down-regulated in Epab-/- mice. The expression levels of 47 target genes that were previously identified as potential biomarkers of human embryo viability were cross-analyzed in Epab driven mouse cumulus microarrays. Among those, 13 were found to be differentially expressed in Epab-/- mice, and confirmed by qRT-PCR. These transcripts were previously shown to be associated with oocyte maturation (HAS2, PTGS2), fertilization (HAS2, GREM1, PTGS2, PTX3), early cleavage (HSPB1, TNFAIP6, CCND2), blastocyst development (PTGS2, SDC4), pregnancy (HIST1H4C, CAMK1D, SDC4), and live birth (PTGS2, CAMK1D).ConclusionCandidate cumulus cell marker genes of oocyte and embryo viability identified in human demonstrated altered expression in Epab-deficient female mice where diverse regulations remain to be further investigated. ObjectiveSeveral cumulus cell transcripts have been identified as potential non-invasive biomarkers of human embryo development and implantation. Embryonic poly(A) binding protein (EPAB) is expressed exclusively in Xenopus and mouse oocytes and early embryos, and is required for oocyte maturation. Importantly, although EPAB is not expressed in cumulus cells, cumulus expansion and ovulation are also impaired in Epab-/- mice. We therefore asked whether the oocyte-specific EPAB is required for the optimal expression of cumulus cell-biomarkers of embryo viability. Several cumulus cell transcripts have been identified as potential non-invasive biomarkers of human embryo development and implantation. Embryonic poly(A) binding protein (EPAB) is expressed exclusively in Xenopus and mouse oocytes and early embryos, and is required for oocyte maturation. Importantly, although EPAB is not expressed in cumulus cells, cumulus expansion and ovulation are also impaired in Epab-/- mice. We therefore asked whether the oocyte-specific EPAB is required for the optimal expression of cumulus cell-biomarkers of embryo viability. DesignExperimental study. Experimental study. Materials and MethodsCumulus cells were collected from Epab-/- and Epab+/+ mice 4 hours after hCG injection and three pooled samples were generated for each group. Microarrays were performed for each of the six samples using Affymetrix GeneChip Mouse Gene 1.0 ST Array platform. Probe level expression values were extracted and background adjustment, inter-array quantile normalization and probe set summarization were performed according to the Robust Multi-Chip Average algorithm. Cumulus cells were collected from Epab-/- and Epab+/+ mice 4 hours after hCG injection and three pooled samples were generated for each group. Microarrays were performed for each of the six samples using Affymetrix GeneChip Mouse Gene 1.0 ST Array platform. Probe level expression values were extracted and background adjustment, inter-array quantile normalization and probe set summarization were performed according to the Robust Multi-Chip Average algorithm. Results663 genes were up-regulated and 1205 genes were down-regulated in Epab-/- mice. The expression levels of 47 target genes that were previously identified as potential biomarkers of human embryo viability were cross-analyzed in Epab driven mouse cumulus microarrays. Among those, 13 were found to be differentially expressed in Epab-/- mice, and confirmed by qRT-PCR. These transcripts were previously shown to be associated with oocyte maturation (HAS2, PTGS2), fertilization (HAS2, GREM1, PTGS2, PTX3), early cleavage (HSPB1, TNFAIP6, CCND2), blastocyst development (PTGS2, SDC4), pregnancy (HIST1H4C, CAMK1D, SDC4), and live birth (PTGS2, CAMK1D). 663 genes were up-regulated and 1205 genes were down-regulated in Epab-/- mice. The expression levels of 47 target genes that were previously identified as potential biomarkers of human embryo viability were cross-analyzed in Epab driven mouse cumulus microarrays. Among those, 13 were found to be differentially expressed in Epab-/- mice, and confirmed by qRT-PCR. These transcripts were previously shown to be associated with oocyte maturation (HAS2, PTGS2), fertilization (HAS2, GREM1, PTGS2, PTX3), early cleavage (HSPB1, TNFAIP6, CCND2), blastocyst development (PTGS2, SDC4), pregnancy (HIST1H4C, CAMK1D, SDC4), and live birth (PTGS2, CAMK1D). ConclusionCandidate cumulus cell marker genes of oocyte and embryo viability identified in human demonstrated altered expression in Epab-deficient female mice where diverse regulations remain to be further investigated. Candidate cumulus cell marker genes of oocyte and embryo viability identified in human demonstrated altered expression in Epab-deficient female mice where diverse regulations remain to be further investigated.