Transcription of the human apolipoprotein A-II is down-regulated by the first intron of its gene.

Several reports indicate that apoA-II, the second most abundant HDL protein, plays a crucial role in modulating the anti-atherogenic behavior of HDL. Regulatory elements located 5' to the human apoA-II promoter have been previously described. In this paper we report that the first intron of the human apoA-II gene down-regulates its own promoter and the ubiquitous thymidine kinase promoter both in HepG2 and Caco-2 cells. The intron contains three sequences which bind nuclear proteins, thus demonstrating the presence of regulatory elements downstream of the transcription start site of the apoA-II gene.