Dynamics of the Transcriptome in the Primate Ovulatory Follicle

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.