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Transcription factors inhibit or assist RNA polymerases in the initiation and maintenance of transcription; however, the cell specific expression and roles of transcription factors within bovine ovarian follicles during development are unknown. The aim of present study was to determine if the expression of transcription factors in theca and granulosa cells differ between the dominant and the largest subordinate follicles at different stages of the follicle wave. We used a bovine cDNA microarray to screen granulosa and theca cells from dominant and subordinate follicles for differential expression of genes coding for transcription factors. Expression was confirmed using reverse transcription polymerase chain reaction and differences in mRNA abundance further examined at Emergence, Selection and Dominance stages of the follicle wave. We have identified five genes encoding for transcription factors that have not been previously described in developing follicles with greater mRNA abundance in subordinate compared to dominant follicles. The genes (and their putative roles) are CEBP-beta (responsible for luteinization), SRF (cell survival), FKHRL1 (stimulates apoptosis), NCOR1 (modulation of the actions of the oestradiol receptor) and Midnolin (control of development via regulation of mRNA transport in cells)., ((c) 2007 Wiley-Liss, Inc.)

The cellular form of the prion protein (PrP(C)) has been detected in many tissues including reproductive tissues. While its function is unclear, it has been suggested to act as a receptor for an unidentified ligand and/or as an antioxidant agent. We tested the hypothesis that PrP(C) is differentially expressed in dominant, growing, compared to subordinate bovine ovarian follicles. Using both microarray analysis and quantitative real-time PCR, the level of prion protein mRNA (Prnp) in both theca and granulosa cells was measured. We found that levels of Prnp were significantly higher in the theca cells of dominant compared to subordinate follicles but similar among granulosa cells from different follicles. This difference was apparent immediately after selection of the dominant follicle and continued to the dominance stage of the follicle wave. Levels of the protein for PrP(C) were also higher (P < 0.05) in theca cells of dominant compared to subordinate follicles. In conclusion, elevated PrP(C) was associated with ovarian follicle growth and development and we suggest that it may play a role in the success of follicle development., (2007 Wiley-Liss, Inc)