Transcriptomic correlates of changes in bovine oviduct epithelial cell function during the estrous cycle

The oviduct plays a central role in mammalian reproduction, providing the microenvironment for the final maturation of gametes, capacitation of spermatozoa, transport of gametes, fertilization, and early cleavage-stage embryonic development. To fulfill these specialized tasks, the oviduct epithelium undergoes marked morphological and functional changes during the estrous cycle. In the ampulla of the bovine oviduct, ciliated cells predominate at diestrus whereas both ciliated and secretory cells are found at estrus. To identify molecular correlates of these marked morphological changes, we performed mRNA expression profiling of ipsilateral oviduct epithelial cells at estrus and diestrus using a combination of subtracted cDNA libraries and cDNA array hybridization. Two subtracted libraries were produced to enrich cDNAs of up-regulated genes at estrus and at diestrus, respectively. 1,536 cDNA clones of each library were analyzed by array hybridization with cDNA probes derived from six Simmental heifers, three of them slaughtered at estrus and three at diestrus. In total, 84 different cDNAs were identified by sequencing, of which 42 matched bovine genes or their homologs with known functions and 42 matched genes without a known function. Half of the genes (n=42) were expressed at a higher level at estrus, for the other (n=42) expression levels were higher at diestrus. The regulated genes or their products represented a variety of functional classes, including immune-related proteins, proteins involved in protein modifications and secretion, signaling molecules and regulators of transcription. At estrus especially genes involved in regulation of protein secretion and protein modification were up-regulated whereas at diestrus transcripts of genes involved in transcription regulation and transport processes predominated. The set of genes identified will be important for the evaluation of in vitro culture of oviduct epithelial cells and for the understanding of interactions between gametes or early embryos and their maternal environment.

Grant support: DFG FOR 478/1.