Hormonal control of H-type alpha(1-2)fucosyltransferase messenger ribonucleic acid in the mouse uterus

The H epitope, an alpha(1-2)fucosylated carbohydrate structure, has been im plicated in initial attachment of the murine blastocyst to luminal uterine epithelial cells in vitro. In this study, the expression of the H-type alph a(1-2)fucosyltransferase (FUT1) gene was examined in endometrium of mice. N orthern blotting of luminal epithelial RNA identified a single 6.2-kilobase transcript. In situ hybridization studies showed a signal for FUT1 mRNA on Days 1-3 of pregnancy in glands and luminal epithelium, The signal diminis hed by Day 4 and could not be detected on Day 5 of pregnancy. The in situ s ignal in endometrial epithelia was highest at estrus and metestrus and was absent at diestrus. Estrogen treatment after ovariectomy gave strong FUT1 m RNA expression in epithelia, but with progesterone, progesterone + estrogen , or vehicle, no message could be detected, A semiquantitative reverse tran scription-polymerase chain reaction (PCR) analysis of FUT1 mRNA from lumina l epithelium generated large amounts of PCR product on Day 1 of pregnancy; this diminished on Days 2, 3, and 4, and the product was barely detectable on Day 5. A kinetic analysis of FUT1 activity on Day 1 of pregnancy suggest ed a single enzyme with a Michaelis-Menten constant (K-m) of 0.29 mM toward s phenyl-beta-D-galactoside and of 1.75 mM towards Gal beta(1-3)GalNAc. The se results suggest that expression of the H epitope is regulated at the lev el of FUT1 transcription and that transcription is stimulated by estrogen i n the endometrial epithelium.