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Comment |
Identification of Down-regulated Messenger RNAs in Bovine Granulosa Cells of Dominant Follicles Following Stimulation with Human Chorionic Gonadotropin Ndiaye K, et al .
Molecular determinants and mechanisms involved in ovarian follicular growth, ovulation and luteinization are not well understood. The objective of this study was to identify genes expressed in bovine granulosa cells (GC) of dominant follicles (DF) and down-regulated after hCG-induced ovulation, using the suppression subtractive hybridization (SSH). GC were collected from DF at day 5 of the estrous cycle and from ovulatory follicles (OF) obtained 23 h following injection of hCG. A subtracted cDNA library (DF-OF) was generated and screened using unsubtracted (DF, OF) and subtracted (DF-OF, OF-DF) cDNAs as complex (32)P-probes. A total of 32 non-redundant cDNAs were identified: 23 cDNAs matched with sequences of known biological function and 9 cDNAs with complete or partial sequences of undefined biological function. Detection of genes known to be down-regulated during the periovulatory period in the bovine species, such as CPD, CYP11A1, CYP19A1, FSHR, LRP8/ApoER2 and SERPINE2, validated the physiological model and analytical techniques used. For a subset of genes such as ARFGAP3, CYP11A1, CYP19A1, FSHR, FST, GJA1, IDH3, INHBA, LHCGR, LHCGR lacking exon 10, PRC1, PRG1, RPA2, SCD and TRIB2, gene expression profiles were compared by virtual Northern blot or reverse transcriptase-polymerase chain reaction from follicles obtained at different developmental stages. Results confirmed a down-regulation of the respective mRNAs in GC of OF compared with that of DF. We conclude that we have identified novel genes that are down-regulated by hCG in bovine GC of DF during the periovulatory period, which may contribute to follicular growth, ovulation and/or luteinization.
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