IDENTIFICATION OF A CIS-REGULATORY ELEMENT FOR DELTA(12)-PROSTAGLANDIN J(2)-INDUCED EXPRESSION OF THE RAT HEME OXYGENASE GENE

We recently reported that Delta(12)-prostaglandin (PG) J(2) caused various cells to synthesize heme oxygenase, HO-1 (Koizumi, T., Negishi, M., and Ichikawa, A. (1992) Prostaglandins 43, 121-131). Here we examined the molecular mechanism underlying the Delta 12-PGJ(2)-induced HO-1 synthesis. Delta(12)-PGJ(2) markedly stimulated the promoter activity of the 5'-flanking region of the rat HO-1 gene from -810 to +101 in rat basophilic leukemia cells. From functional analysis of various deletion mutant genes we found that the Delta 12-PGJ(2)-responsive element was localized in a region from -690 to -660, containing an E-box motif, which was essential for the Delta(12)-PGJ(2)-stimulated promoter activity. When the region containing the Delta(12)- PGJ(2)-responsive element was combined with a heterologous promoter, SV40 promoter, in the sense and antisense direction, the element showed an enhancer activity in response to Delta(12)-PGJ(2). Gel mobility shift assays demonstrated that Delta(12)-PGJ(2) specifically stimulated the binding of two nuclear proteins to the E-box motif of this region. These results indicate that Delta(12)-PGJ(2) induces the expression of the rat HO-1 gene through nuclear protein binding to a specific element having an E-box motif.