CHROMOSOMAL ORGANIZATION OF THE GENE ENCODING PORCINE ANTILEUKOPROTEINASE AND FUNCTIONAL-ANALYSIS OF THE PROMOTER REGION IN ENDOMETRIAL ANDPLACENTAL CELLS

The apparent preferential expression of the elastase/cathepsin G prote ase inhibitor antileukoproteinase (ALP) in endometrium of species with epitheliochorial placenta suggests mechanisms of transcriptional regu lation unique to these mammalian species. To begin to define the cis-a cting regulatory elements involved in the endometrial transcription of the ALP gene; the porcine ALP gene was isolated-and characterized. Th e porcine gene spans at least 13 kb and consists of 5 exons and 4 intr ons. This genomic structure, except for an additional exon, is similar to that of the human gene where the first three exons encode the sign al peptide, trypsin/cathepsin G binding region, and elastase binding r egion, respectively. The positions of the 16 cysteine residues in exon s 2 and 3 of the human gene are conserved in the porcine gene. The por cine gene contains a TATA box at -29 nucleotide (nt), and sequences wi th limited homology to those which might bind the transcription factor s AP-1, AP-2, Sp-1 and Oct-1. The functional promoter activity of the ALP-5' Banking DNA was examined using chimeric ALP-chloramphenicol ace tyl transferase (CAT) DNA constructs. after transient transfection in human (ECC-I, Ishikawa) and rabbit (HRE-H9) endometrial and human trop hoblastic (JEG-3) cell Lines. A 887 nt fragment of the ALP-5'-flanking region (-887ALP-pCAT-E) was active in these cel lines, with the highe st promoter activity observed in the ECC-1. Progressive 5' deletion of the 887 nt fragment up to -243 nt had no effect on CAT gene expressio n in all cell lines, relative to the longest construct. Results sugges t that the approximately 240 bp fragment most proximal to the transcri ption initiation site confers basal and limited endometrial tissue-spe cific promoter activity to the ALP gene 5'-flanking region. These stud ies also establish the ECC-1 cell line as an in vitro model system to elucidate the control of ALP gene transcription in the endometrium.