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(1) GALECTIN-15 IS THE NOVEL 14K PROGESTERONE-MODULATED PROTEIN FROM THE UTERUS OF SHEEP THAT FORMS CRYSTALLINE INCLUSION BODIES IN ENDOMETRIAL EPITHELIUM AND CONCEPTUS TROPHECTODERM. Gray, Allison1, Meyer, Jennifer1, Adelson, David1, Bazer, Fuller1, Burghardt, Robert2, Spencer, Thomas 1, 1 Texas A&M University, College Station, TX2 Texas A&M University, College Station, TX ABSTRACT- Gene expression profiling was conducted using endometria from cyclic (C) and pregnant (Px) sheep to identify genes regulating conceptus implantation. Individual random clones (n=5,000) from a Day (D) 14 Px endometrial cDNA library were isolated, sequenced, and arrayed. Transcriptional profiling of D14 C and Px endometrium discovered that ovgal11 (AF252548), a novel member of the galectin family of secreted animal lectins, was ∼10-fold greater in D14 Px than D14 C sheep. The ovine endometrial galectin cDNA had a predicted ORF of 414 nt that encodes a protein of 137 aa. The inferred amino acid sequence displayed over 40% identity to galectins -10 (Charcot-Leyden crystal protein) and -13 (placental protein 13) and was named galectin-15 due to lack of an orthologue. Galectin-15 contains a predicted carbohydrate recognition domain (CRD) of prototypical galectins and a LDV/RGD integrin binding domain. In C and Px ewes, endometrial galectin-15 mRNA was not detected before D10, increased ∼13-fold between D10 and D14, and then noticeably decreased between D14 and D16 in C, but not Px sheep. Galectin-15 mRNA was observed only in the endometrial LE and not in the conceptus. In C ewes, galectin-15 protein was detected primarily in the cytoplasm of the endometrial lumenal epithelium (LE). In uteri of D14 to D20 Px ewes, galectin-15 protein was concentrated near and on the apical surface of the LE and localized to the surface and within discrete cytoplasmic structures of the conceptus trophectoderm. In uterine flushes of Px ewes, galectin-15 protein (∼15 kDa) was low on D10 and D12, but abundant on D14 and D16 and was functional in binding fetuin and lactose and mannose sugars. Galectin-15 protein from the uterine flush and uterine milk could be immunoprecipitated with an antibody that recognizes a 14K progesterone-modulated protein from the uterus of sheep that forms crystalline inclusion bodies in the endometrial LE and conceptus trophectoderm (Biol Reprod 1990; 43:80). Thus, galectin-15 is synthesized and secreted by the endometrial LE and may regulate conceptus implantation through cross-linking cell-surface glycoprotein or glycolipid receptors on the trophectoderm and LE cell surfaces to stimulate trophectoderm proliferation, migration, and firm attachment and adhesion to the endometrial LE. USDA NRI Grant 2001-02259 KEY WORDS: endometrium, implantation, ovine, galectin |
