Ovarian mRNA Expression and Regulation of Matrix Metalloproteinase 16 in the Domestic Hen

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In mammals, membrane-bound matrix metalloproteinases (MT-MMPs) are thought to play an important role in ovarian remodeling. However, the role and regulation of these proteases in the ovary of birds remain largely unknown. One of MT-MMPs, i. e., MMP-16, has been found in the hen ovary; therefore, this study was undertaken to examine whether the transcript level of MMP-16 changes during follicle development and whether gonadotropins and estrogen are involved in the regulation of this enzyme expression. The relative expression of MMP-16 mRNA in the ovarian follicles (white, yellowish, small yellow, and the granulosa and theca layers of three of the largest yellow preovulatory [F3-F1]) was examined 22 h and 3 h before F1 follicle ovulation as well as following equine chorionic gonadotropin (eCG) or tamoxifen (estrogen receptor modulator, TMX) treatments by quantitative real-time polymerase chain reaction (qRT-PCR). MMP-16 transcripts were detected in all examined ovarian tissues of control and treated hens. The relative expression of MMP-16 depended on follicular size/maturation and the layer of the follicular wall. A relatively higher expression of MMP-16 mRNA in the granulosa layer at 3 h compared to 22 h before ovulation of F1 was found. The injections of eCG decreased transcript abundance of MMP-16 in white and small yellow follicles, as well as in the theca layer of F3-F2 and the granulosa layer of the F1 follicle. In turn, TMX caused an increase in mRNA expression of MMP-16 in the theca layer of the largest preovulatory follicles and a decrease in the granulosa layer of the F1 follicle. Our results provide the first mRNA expression analysis of MMP-16 in the hen ovary under different physiological states. In addition, results indicate a possible role of gonadotropins and estrogen in regulating the transcription of MMP-16 in the chicken ovary.