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Comment |
New insights into the pathogenesis of cystic follicles in cattle: microarray analysis of gene expression in granulosa cells. Grado-Ahuir JA et al. Ovarian follicular growth and development are regulated by extraovarian and intraovarian factors, which influence granulosa cell proliferation and differentiation. However, molecular mechanisms that drive follicular growth are not completely understood. Ovarian follicular cysts are one of the most common causes of reproductive failure in dairy cattle. Nevertheless, the primary cause of cyst formation has not been clearly established. Gene expression comparison may aid in elucidation of causes of ovarian cyst disease. Our objective was to identify differentially-expressed genes in ovarian granulosa cells between normal dominant and cystic follicles of cattle. Granulosa cells and follicular fluid were isolated from dominant and cystic follicles collected via either ultrasound-guided aspiration from dairy cows (n = 24) or slaughterhouse ovaries from beef cows (n = 23). Hormonal analysis for progesterone, estradiol, and androstenedione in follicular fluid was performed by RIA. Total RNA was extracted and hybridized to 6 Affymetrix GeneChip Bovine Genome Arrays. Abundance of mRNA for differentially-expressed selected genes was determined through quantitative real-time reverse transcription PCR (qRT-PCR). Follicular cysts showed greater progesterone, lesser estradiol, and no differences in androstenedione concentrations compared to noncystic follicles. A total of 163 gene sequences were differentially expressed (P < 0.01), with 19 up regulated and 144 down regulated. From selected target genes, qRT-PCR confirmed angiogenin (ANG), prostaglandin E2 receptor 4 (PTGER4) and G-protein coupled receptor 34 (GPCR34) as up regulated in cystic follicles, and Indian hedgehog protein precursor (IHH) and secreted frizzled-related protein 4 (SFRP4) as down regulated in cystic follicles. Further research is required to elucidate the role of these factors in follicular development and cyst formation.
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