Neural cell line-specific regulatory DNA cassettes harboring the murine D1A dopamine receptor promoter

Transcription in the human and rat D1A dopamine receptor genes proceeds from two distinct promoters in neuronal cells while only the downstream intronic promoter is active in renal cells. To investigate the utility of these promoters in the brain cell-specific expression of transgenes, we now studied the 5' flanking region of the murine D1A gene. We confirmed the presence of two functional promoters utilized for the tissue-specific regulation of this gene similar to its human and rat homologues. The cloned 1.4-kb genomic fragment spans nucleotides - 967 to + 384 relative to the first ATG codon and includes intron 1 between bases -534 to -420. Transient expression analyses using various chloramphenicol acetyltransferase constructs revealed that the murine D1A upstream promoter fused with the human D1A gene activator sequence ActAR1 has potent transcriptional activity in a D1A-expressing neuronal cell line but not in other cell lines tested including renal (OK cells), glial (C6) and hepatic (HepG2), suggesting that this hybrid construct harbors neural cell-specific elements. The availability of potent regulatory DNA cassettes harboring the murine D1A gene promoter could aid testing the neuronal-specific expression of transgenes in vivo.