Galectin 15 (LGALS15) functions in trophectoderm migration and attachment

Abstract

Galectin 15 (LGALS15) is expressed specifically by the endometrial luminal epithelium (LE) of the ovine uterus in concert with blastocyst growth, elongation, and implantation. LGALS15 contains a predicted carbohydrate recognition domain (CRD) as well as LDV and RGD recognition sequences for integrin binding. Studies tested the hypothesis that LGALS15 is a secreted regulator of blastocyst development, as well as growth, migration, adhesion, and apoptosis of trophoblast. Bovine embryos were produced in vitro by standard conditions, and putative zygotes were cultured in the presence of recombinant ovine LGALS15. Rates of embryo cleavage and blastocyst formation were not affected by LGALS15. LGALS15 moderately increased proliferation of ovine trophectoderm (oTr) cells. Staurosporine elicited apoptosis of oTr cells, which could be partially inhibited by LGALS15. Migration of oTr cells was stimulated by LGALS15 that was dependent on Jun N-terminal kinase (JNK). A dose-dependent increase in oTr cell attachment to LGALS15 was found that could be inhibited by cyclic GRGDS, but not GRADS, peptides. Mutation of the LDVRGD integrin binding sequence of LGALS15 to LADRAD decreased its ability to promote oTr cell attachment, whereas mutation of the CRD had little effect. LGALS15 induced formation of robust focal adhesions in oTr cells that was abolished by mutation of the LDVRGD sequence. Collectively, these results support the hypothesis that LGALS15 stimulates trophectoderm cell migration and attachment via integrin binding and activation which are critical to blastocyst elongation and implantation.

Enhanced focal adhesion assembly reflects increased mechanosensation and mechanotransduction at maternal–conceptus interface and uterine wall during ovine pregnancy

“…Another recently identified progesterone-induced member of the galectin family, LGALS15, which is found in uterine histotroph (Gray et al 2004) and capable of inducing focal adhesions in 2D cultures (Farmer et al 2008), was detected within and at the apical surface of LE in the non-gravid horn and within the LE and superficial glandular epithelium of interplacentomal endometrium from gravid horns. The majority of LGALS15 immunostaining was sequestered within the Tr in gravid uterine horns (Fig.…”

“…Large accumulations of SPP1 protein, which form a thick matrix along with lesser amounts of LGALS15, were present at the interface between uterine and placental epithelia that were actively forming focal adhesions in response to binding ECM ligand. In contrast to the best-studied ECM mechanosensor, FN (reviewed in Vogel 2006), the mechanosensory functions of SPP1 and LGALS15 have not been examined in detail, although the diverse functions of these proteins suggest they could play such a role (reviewed in Denhardt & Guo 1993, Butler et al 1996, Weber & Cantor 1996, Sodek et al 2000, Johnson et al 2003a, Farmer et al 2008.…”

Exosomes, endogenous retroviruses and toll-like receptors: pregnancy recognition in ewes

“…An established oTr1 cell line from day 15 conceptuses was used for in vitro studies as described previously (Farmer et al 2008). The cells were cultured in DMEM F12 that included 10% fetal bovine serum, 50 U penicillin, 50 mg streptomycin, 0.1 mM each of nonessential amino acids, 1 mM sodium pyruvate, and 0.7 mM insulin.…”

Genes Regulating Maternal Recognition of Pregnancy in Domestic Animals: an Update

“…Galectin-9 has been identified in mid-and late-secretory and decidual phases in human endometrium, with the expression in glandular and luminal epithelial but not stromal or immune cells (Smalley and Ley 2005). Recently, a new galectin family member, galectin-15, has been discovered in the endometrium of sheep, which has a prospective role in trophectoderm attachment (Farmer et al 2008). Ovine endometrial Galectin-15 contains a conserved carbohydrate recognition domain (CRD) that binds β-galactosides, but the carbohydrate-binding specificity for each galectin appears to be different.…”