Discovery and characterization of an epithelial-specific galectin in the endometrium that forms crystals in the trophectoderm

Abstract

Secretions of the uterus support survival and growth of the conceptus (embryo͞fetus and associated membranes) during pregnancy. Galectin-15, also known as OVGAL11 and a previously uncharacterized member of the galectin family of secreted ␤-galactoside lectins containing a conserved carbohydrate recognition domain and a separate putative integrin binding domain, was discovered in the uterus of sheep. In endometria of cyclic and pregnant sheep, galectin-15 mRNA was expressed specifically in the endometrial luminal epithelium but not in the conceptus. In pregnant sheep, galectin-15 mRNA expression appeared in the epithelia between days 10 and 12 and increased between days 12 and 16. Progesterone induced and IFN-stimulated galectin-15 mRNA in the endometrial epithelium. Galectin-15 protein was concentrated near and on the apical surface of the endometrial luminal epithelia and localized within discrete cytoplasmic crystalline structures of conceptus trophectoderm (Tr). In the uterine lumen, secreted galectin-15 protein increased between days 14 and 16 of pregnancy. Galectin-15 protein was functional in binding lactose and mannose sugars and immunologically identical to the unnamed M r 14,000 (14K) protein from the ovine uterus that forms crystalline inclusion bodies in endometrial epithelia and conceptus Tr. Based on the functional studies of other galectins, galectin-15 is hypothesized to function extracellularly to regulate Tr migration and adhesion to the endometrial epithelium and intracellularly to regulate Tr cell survival, growth, and differentiation. Galectins may be useful as cellular and molecular markers for endometrial function and receptivity, to enhance conceptus survival and development, and to evaluate and enhance fertility.

Galectin-15 in ovine uteroplacental tissues

“…In the endometrium, galectin-15 protein had a nucleocytoplasmic distribution within the LE and sGE and was also concentrated near and on the apical surface. Further, secreted galectin-15 protein was abundant in the histotroph recovered from the uterine lumen and was immunologically similar to the previously unknown 14 kDa protein that is a component of crystals in the endometrial epithelium and conceptus trophectoderm (Gray et al 2004, Kazemi et al 1990). Galectins bind b-galactosides and functionally crosslink glycoprotein and glycolipid receptors on the surface of cells, which initiates biological responses that include cell proliferation, differentiation, motility, adhesion and apoptosis (Cooper 2002, Yang & Liu 2003, Liu & Rabinovich 2005.…”

“…Recently, a new galectin family member and component of uterine histotroph, galectin-15, was discovered in the endometrium of sheep (Gray et al 2004). Galectin-15 was originally identified in ovine intestinal epithelium as being induced in response to infection by Haemonchus contortus, a nematode parasite (Dunphy et al 2000).…”

Galectin-9 Acts as a Prognostic Factor with Antimetastatic Potential in Hepatocellular Carcinoma

“…To date, 15 members of the galectin family have been identified (Gray et al, 2004). ) is a member of them, and it was first identified as an eosinophil chemoattractant and activation factor (Matsumoto et al, 1998;Matsushita et al, 2000; Zhao-Yang Zhang 1,2 , Jia-Hong Dong 2 *, Yong-Wei Chen 2 , Xian-Qiang Wang 2 , Chong-Hui Li 2 , Jian Wang 2 , Guo-Qiang Wang 2 , Hai-Lin Li 2 , Xue-Dong Wang 2 Matsumoto et al, 2002;Saita et al, 2002).…”

Lectins: Tools for the Molecular Understanding of the Glycocode

“…137 Galectins are a growing family of b-galactoside-specific proteins of which 15 members have been identified in mammals. 138 Many tumours, such as colon, thyroid and breast carcinomas, express both galectin-1 and -3, and it has been suggested that galectin-3 is a metastasis marker. 139 Among the degenerative processes that they can mediate, galectins may favour metastasis by binding glycoconjugates of the extracellular matrix and subsequent intravasation of the tumour cell into the blood vessels.…”