Characterization of the gene for the mouse prostaglandin E receptor subtype EP2: tissue-specific initiation of transcription in the macrophage and the uterus

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Abstract
Genomic DNA clones for the mouse prostaglandin (PG) E receptor subtype EP2 were isolated and characterized. The mouse EP2 gene is composed of 2 exons and 1 intron, and spans 16 kb. The intron which is approx. 12 kb in length is located at the end of the sixth transmembrane domain, as with other prostanoid receptor genes. Based on this structure, transcripts were analysed in endotoxin-treated macrophages and pseudopregnant uteri, in which abundant expression of EP2 mRNA was observed. Sequence analysis of cDNA clones from these origins and Northern hybridization of these RNAs revealed that the uterine EP2 mRNA (U-type) has a longer 5ʹ-untranslated region than the macrophage EP2 transcript (M-type). The major transcription initiation sites for M-type and U-type EP2 are located 124 and 769 bp upstream of the translation start site, respectively. The M-type was expressed in various tissues, whereas the U-type was found only in the uterus. The 2 kb segment containing the immediate 5ʹ-flanking and 5ʹ-noncoding regions contain three consensus sequences for the NF-IL6 binding site, one consensus sequence for the NF-κB binding site, four AP-2 consensus sequences, one AP-4 consensus sequence, one potential cAMP response element, and one potential progesterone response element. These results suggest that EP2 gene expression in the macrophage and uterus is under the control of distinct mechanisms involving alternative promoters.