title: Expression of uterine lipocalin 2 and its receptor during early- to mid-pregnancy period in mares.
abstract: From previous cDNA subtraction studies analyzing gene expression in equine endometrium, high lipocalin 2 (LCN2) mRNA expression was found in the gravid endometrium. In the uterus, LCN2 may transport hydrophobic molecules and siderophores with iron, or may form a complex with another protein, however, the expression of uterine LCN2 beyond day 20 of equine pregnancy and its receptor has not been characterized. To study the expression and potential roles of uterine LCN2 from pre-implantation to mid-gestation period, stage-specific endometrial samples were obtained from day 13 (day 0 = ovulation) cyclic and days 13, 19, 25, and 60 to 131 pregnant mares. Expression of LCN2 mRNA increased in day 19 gravid endometrium and was abundant from day 60 onward. The expression of LCN2 mRNA was localized to the glandular epithelium. LCN2 protein was detected in day 25 gravid endometrium and luminal fluid, and the protein was localized to the glandular epithelium and luminal cavity, whereas LCN2 receptor expression was found in luminal and glandular epithelium and trophectoderm throughout the experimental period. The presence of matrix metalloproteinase-9 (MMP9) was also examined because MMP9 is known to form a complex with LCN2. Although MMP9 and LCN2 were both found in luminal fluid from day 25 pregnant uterus, the complex of these proteins was not detected. Localization of the receptor in the trophectoderm suggests that endometrial LCN2 could play a role in carrying small substances from the mother to fetus in the equine species.
authors.affiliation: Department of Applied Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-8555, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Haneda
authors.affiliation: Laboratory of Veterinary Physiology, Department of Veterinary Medicine, Tokyo University of Agriculture and Technology, Tokyo 183-0057, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nagaoka
authors.affiliation: Department of Applied Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-8555, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nambo
authors.affiliation: Chiba Agricultural Insurance Association, Chiba 260-0031, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Kikuchi
authors.affiliation: Animal Resource Science Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Ibaraki 319-0206, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Nakano
authors.affiliation: Animal Resource Science Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Ibaraki 319-0206, Japan.
authors.forename: Junyou
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Applied Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-8555, Japan.
authors.forename: Motozumi
authors.initials: M
authors.lastname: Matsui
authors.affiliation: Department of Applied Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-8555, Japan.
authors.forename: Yo-Ichi
authors.initials: YI
authors.lastname: Miyake
authors.affiliation: Animal Resource Science Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Ibaraki 319-0206, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Imakawa
mesh_terms: D000818:Animals; D005260:Female; D006736:Horses; D000071068:Lipocalin-2 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D027701:Organic Cation Transport Proteins / Q000378:metabolism*; D011247:Pregnancy; D014599:Uterus / Q000378:metabolism*
chemical_list: D000071068:Lipocalin-2; D027701:Organic Cation Transport Proteins; D020780:Matrix Metalloproteinase 9
keywords: Endometrium; Equine; LCN2 receptor (SLC22A17); Lipocalin 2 (LCN2); Matrix metalloproteinase-9 (MMP9)