Project description:Follicular somatic cells (mural granulosa cells and cumulus cells) and the oocyte communicate through paracrine interactions and through direct gap junctions between oocyte and cumulus cells. Considering that mural and cumulus cells arise through a common developmental pathway and that their differentiation is essential to reproductive success, understanding how these cells differ is a key aspect to understanding their critical functions. Changes in global gene expression before and after an ovulatory stimulus were compared between cumulus and mural granulosa cells to test the hypothesis that mural and cumulus cells are highly differentiated at the time of an ovulatory stimulus and further differentiate during the periovulatory interval. The transcriptomes of the two cell types were markedly different (>1500 genes) before an ovulatory hCG bolus but converged after ovulation to become completely overlapping. The predominant transition was for the cumulus cells to become more like mural cells after hCG. This indicates that the differentiated phenotype of the cumulus cell is not stable and irreversibly established but may rather be an ongoing physiological response to the oocyte. We compared transcriptomes of mural granulosa cells isolated from the follicles before (PM-GC) and after (VVM-GC) an ovulatory stimulus. These data were analyzed with previously published cumulus cells data to compare transitions in granulosa cell state before and after an ovulatory stimulus with transitions in cumulus cells.
Project description:Follicular somatic cells (mural granulosa cells and cumulus cells) and the oocyte communicate through paracrine interactions and through direct gap junctions between oocyte and cumulus cells. Considering that mural and cumulus cells arise through a common developmental pathway and that their differentiation is essential to reproductive success, understanding how these cells differ is a key aspect to understanding their critical functions. Changes in global gene expression before and after an ovulatory stimulus were compared between cumulus and mural granulosa cells to test the hypothesis that mural and cumulus cells are highly differentiated at the time of an ovulatory stimulus and further differentiate during the periovulatory interval. The transcriptomes of the two cell types were markedly different (>1500 genes) before an ovulatory hCG bolus but converged after ovulation to become completely overlapping. The predominant transition was for the cumulus cells to become more like mural cells after hCG. This indicates that the differentiated phenotype of the cumulus cell is not stable and irreversibly established but may rather be an ongoing physiological response to the oocyte.
Project description:Experiments were designed to evaluate changes in the transcriptome (mRNA levels) in the ovulatory, luteinizing follicle of rhesus monkeys, using a controlled ovulation (COv) model that permits analysis of the naturally selected, dominant follicle at specific intervals (0, 12, 24, 36 hours) after exposure to an ovulatory (exogenous hCG) stimulus during the menstrual cycle. Total RNA was prepared from individual follicles (n=4-8/timepoint), with an aliquot used for microarray analysis (AffymetrixTM Rhesus Macaque Genome Array) and the remainder applied to quantitative real-time PCR (q-PCR) assays. The microarray data from individual samples distinctly clustered according to timepoints, and ovulated follicles displayed markedly different expression patterns from unruptured follicles at 36 h. Between timepoint comparisons revealed profound changes in mRNA expression profiles. The dynamic pattern of mRNA expression for steroidogenic enzymes (CYP17A, CYP19A, HSD3B2, HSD11B1, HSD11B2), StAR, and gonadotropin receptors (LHCGR, FSHR) as determined by microarray analysis correlated precisely with those from blinded q-PCR assays. Patterns of mRNA expression for EGF-like factors (AREG, EREG) and processes (HAS2, TNFAIP6) implicated in cumulus-oocyte maturation/expansion were also comparable between assays. Thus, several mRNAs displayed the expected expression pattern for purported theca (e.g., CYP17A, AREG), granulosa (CYP19A, FSHR), cumulus (HAS2, TNFAIP6) cell, and surface epithelium (HSD11B) related genes in the rodent/primate preovulatory follicle. This database will be of great value in analyzing molecular and cellular pathways associated with periovulatory events in the primate follicle (e.g. follicle rupture, luteinization, inflammatory response, and angiogenesis), and for identifying novel gene products controlling mammalian fertility. Keywords: time course Total RNA was prepared from individual follicles (n=4-8/timepoint). Dominant follicles were selected specific intervals (0, 12, 24, 36 hours) after exposure to an ovulatory (exogenous hCG) stimulus during the menstrual cycle.