Gene Expression in Endocrine Tissues
(T458) CLONING AND ANALYSIS OF THE OVINE GALECTIN-15 PROMOTER.
Lewis, Shaye1, Carpenter, Karen1, Gray, Allison1, Fleming, Jo-Ann1, Bazer, Fuller1, Spencer, Thomas1, 1 Texas A&M University, College Station, Texas
ABSTRACT- Galectin-15, a new member of the secreted beta-galactoside lectin family, is expressed only in the endometrial luminal epithelium (LE) and superficial glandular epithelium (sGE) of the ovine uterus and is hypothesized to regulate peri-implantation conceptus growth by stimulating trophectoderm proliferation and migration. Galectin-15 is induced by progesterone between Days 10 and 12 of pregnancy, coincident with down-regulation of progesterone receptor (PR). Galectin-15 is also stimulated by interferon tau (IFN) from the conceptus between Days 14 and 16 of pregnancy, even though Stat1 and Stat2 are not expressed in the LE. Given the lack of a classical JAK-Stat pathway in the LE, the IFN stimulation of genes, such as galectin-15, Wnt7a and cathepsin L, in the endometrial LE is hypothesized to involve a non-classical IFN signaling pathway. To investigate the transcriptional regulation of galectin-15, an ovine genomic DNA library was screened with a galectin-15 cDNA, and a clone containing about 15 kb of genomic DNA was isolated. A 2.3-kb piece was identified by Southern blotting and sequenced. Sequence analysis found that it contained about 1.57-kb of the 5′ promoter/enhancer region as well as Exons 1 and 2. The galectin-15 promoter (-364 to +1) contained a predicted transcriptional start site at -40 and a TATA box at -68 relative to the translational initiation codon (+1) of exon 1. Repeatmasker identified a 1.2-kb LINE-1 element from -364 to -1569. Using the transcription element search system (TESS), the galectin-15 promoter (-364 to +1) contained predicted transcription factor binding sites for activator protein-1 (AP-1), C/EBP, Ets-2, GATA, progesterone receptor (PR), and Sp1 transcription factors. No sites associated with classical Type I IFN signaling (gamma activation sequence element or GAS, IFN stimulated response element or ISRE, and IFN regulatory factor element or IRF-E) were found in the galectin-15 promoter. Future studies will utilize the galectin-15 promoter to discover how progesterone and IFN regulate expression of selected genes in the endometrial LE during pregnancy. Supported by NIH HD32534.
KEY WORDS: galectin, promoter, Ovis aries