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Cloning and initial characterization of nuclear and membrane progesterone receptors in the Fathead Minnow, Pimephales promelas
Citation:
Ellestad, L., K. Stevens, J. Farmer, Dan Villeneuve, AND E. Orlando. Cloning and initial characterization of nuclear and membrane progesterone receptors in the Fathead Minnow, Pimephales promelas. Presented at 45th Annual Meeting of SSR, 18th Ovarian Workshop, College Park, PA, August 12 - 15, 2012.
Impact/Purpose:
Both native progestagens and synthetic progestins have important effects on reproduction that are mediated through progesterone receptors (PRs). They regulate gamete maturation and can serve as precursors for other steroid hormones in vertebrates and act as reproductive pheromones in some fishes. There are four known PRs, including the nuclear progesterone receptor (nPR) and three membrane progesterone receptors (mPRalpha, mPRbeta, and mPRgamma). The objectives of this study were to clone these receptors and investigate their tissue distribution in the fathead minnow (FHM), a species widely distributed in the US with well-characterized reproductive morphology and endocrinology that is used by the EPA as an aquatic toxicological model.
Description:
Both native progestagens and synthetic progestins have important effects on reproduction that are mediated through progesterone receptors (PRs). They regulate gamete maturation and can serve as precursors for other steroid hormones in vertebrates and act as reproductive pheromones in some fishes. There are four known PRs, including the nuclear progesterone receptor (nPR) and three membrane progesterone receptors (mPRalpha, mPRbeta, and mPRgamma). The objectives of this study were to clone these receptors and investigate their tissue distribution in the fathead minnow (FHM), a species widely distributed in the US with well-characterized reproductive morphology and endocrinology that is used by the EPA as an aquatic toxicological model.Full-length coding sequences were obtained through traditional cloning strategies using total RNA extracted from ovary (nPR, mPRalpha, and mPRbeta) or gill (mPRgamma). The open reading frame for nPR consists of 1,923 nucleotides and encodes a protein that is 640 amino acids long. Phylogenetic comparison of the predicted amino acid sequence of FHM nPR with other vertebrates indicates that it is 53-80% identical with other teleosts, 38-46% identical with avian and frog nPR, and 34-44% with mammalian nPR. The open reading frames for each of the three membrane PRs are 1,065 nucleotides in length and are predicted to code for proteins with 354 amino acids. Comparison of the predicted amino acid sequence for FHM mPRalpha with that in other species indicates that it is 77-94% identical with other teleosts, 56-57% identical to avian and frog species, and 51-55% identical with mammals. The predicted amino acid sequence for FHM mPRbeta is also highly similar to that in other vertebrates and was found to be 66-88% identical with other teleosts, 52-54% identical to avian and frog species, and 54-56% identical with mammals. Comparison of the predicted amino sequence for mPRgamma in FHM with other teleosts, avian and frog species, and mammals indicat