Pregnancy-associated endometrial expression of antileukoproteinase gene is correlated with epitheliochorial placentation.

Uterine expression of the mRNA encoding antileukoproteinase (ALP) is highest in pig uterus during mid- to late pregnancy, suggesting a stage of pregnancy-dependent role for this elastase/cathepsin G protease inhibitor in feto-maternal interactions. To examine a potential relationship between uterine synthesis of ALP and the type of placentation in mammalian species, the expression of ALP mRNA and/or protein in pregnant mares, cows, rats, and mice was evaluated. Genomic DNA and mRNA hybridization analyses were performed using a porcine ALP cDNA as probe. The concentration of ALP protein in reproductive tissues was determined by RIA using a polyclonal antibody raised against a synthetic peptide (ALP 16P) corresponding to amino acid residues 21-36 of the porcine ALP protein. A single ALP mRNA transcript of approximately 0.8 kb in length was detected in equine and bovine uterine tissues. The relative abundance of ALP mRNA in equine endometrium increased between days 125-170 (mid-pregnancy), and then decreased by day 215 of pregnancy. Similarly, the steady state levels of ALP mRNA in bovine endometrium and myometrium were higher during mid- to late than during early pregnancy. The levels of ALP mRNA in bovine fetal cotyledon were low and did not change significantly with stage of pregnancy. No hybridization was detected to pregnant rat endometrial tissues, although high stringency Southern blot analysis of porcine, bovine, and rat genomic DNAs using porcine ALP cDNA as probe predicted a high degree of nucleotide sequence homology in their respective ALP genes.(ABSTRACT TRUNCATED AT 250 WORDS)