ANALYSIS AND QUANTITATION OF SPLICING VARIANTS OF THE TPA-INDUCIBLE PGHS-1 MESSENGER-RNA IN RAT TRACHEAL EPITHELIAL-CELLS

Previously we reported that 12-myristate 13-acetate diester (TPA) and dexamethasone regulate the expression of a putative prostaglandin G/H synthase-1 (PGHS-1) gene in a transformed, immortalized rat tracheal e pithelial cell line (EGV-6), Here we report the cloning and sequencing of the cDNA for this gene, Two transcripts of similar size but differ ing in their 5' ends were detected, One transcript contains the comple te 5' coding and noncoding regions, while the other form has an appare ntly intronic sequence in place of these regions, This aberrantly spli ced form lacks codons 1-36, Northern analysis and quantitative PCR ind icated that more than 90% of the PGHS-1 mRNA in EGV-6 cells has the ab errantly spliced 5' end. TPA treatment increases the expression of onl y the complete PGHS-1 mRNA, elevating it to 50% of the total PGHS-1 tr anscript pool, Levels of the aberrant mRNA are not affected by TPA tre atment, A comparison among EGV-6 cells, primary rat tracheal epithelia l (RTE) cultures, and rat fibroblasts showed that all three cell lines have similar levels of the aberrantly spliced PGHS-1 mRNA. RTE cells and fibroblasts, unlike EGV-6 cells, also contain properly spliced PGH S-1 mRNA, at levels 100-fold higher than the level of aberrant PGHS-1 mRNA, TPA does not regulate either of the PGHS-1 transcripts in RTE or rat fibroblast cells, These results confirm the induction of function al PGHS-1 mRNA by TPA only in EGV-6 cells. (C) 1995 Academic Press, In c.