Progesterone Receptor Isoforms in the Mammary Gland of Cats and Dogs
Article first published online: 24 DEC 2012
© 2012 Blackwell Verlag GmbH
Reproduction in Domestic Animals
Special Issue: Canine and Feline Reproduction VII: Reproductive Biology and Medicine of Domestic and Exotic Carnivores. Proceedings of the 7th Quadrennial International Symposium on Canine and Feline Reproduction. Whistler, Canada. 26-29 July 2012.
Volume 47, Issue Supplement s6, pages 313–317, December 2012
How to Cite
Gracanin, A., de Gier, J., Zegers, K., Bominaar, M., Rutteman, G., Schaefers-Okkens, A., Kooistra, H. and Mol, J. (2012), Progesterone Receptor Isoforms in the Mammary Gland of Cats and Dogs. Reproduction in Domestic Animals, 47: 313–317. doi: 10.1111/rda.12045
- Issue published online: 24 DEC 2012
- Article first published online: 24 DEC 2012
- Manuscript Accepted: 24 JUL 2012
- Manuscript Received: 13 JUN 2012
- Mozaiek grant. Grant Number: #017.004.081
Progesterone exerts its effect by binding to specific progesterone receptors (PR) within the cell. In dogs and cats, no data are available on PR isoforms as found in other species. We therefore investigated the sequence of the PR gene and encoded protein in dogs and cats, the expression of PR isoforms in mammary tissue using Western blots and the presence of PR in mammary tissue using immunohistochemistry. Comparison of the amino acid sequence of the canine and feline PR with human PR revealed major differences in the PR-B-specific upstream segment (BUS). However, the essential activation function 3 (AF3) domain was intact in the cat but mutated in the dog. The DNA and ligand-binding domains were highly similar among the species. In cats with fibroadenomatous hyperplasia (FAH), high expression of PR mRNA together with growth hormone (GH), GH receptor (GHR) and IGF-I mRNA was found in comparison with feline mammary carcinomas. Immunohistochemical analysis showed strong nuclear as well as cytoplasmic staining for PR in FAH. Western blot analysis revealed expression of the PR-A and PR-B isoforms in the feline mammary gland. In canine mammary tissue, the most abundant PR staining was found in proliferative zones of the mammary gland. Western blot analyses showed mainly staining for PR-A with lower PR-B staining. It is concluded that in dogs and cats both PR isoforms are expressed. The role of mutations found in the canine PR-B is discussed.