The genomic structure and transcriptional regulation of the rat apelin receptor (APJR) were analysed by rapid amplification of 5′ cDNA ends (5′-RACE), transient expression assays and DNA-protein interaction. Analysis of the 5′-flanking region of a rat genomic clone shows no TATA box, but a putative CAAT box and several putative binding sites for transcription factors are present. Two transcriptional start sites were identified by 5′-RACE, RNase protection and primer extension analyses. Promoter activity was exhibited in the APJR- expressing SH-SY5Y cell line as well as in COS-7 and Chinese hamster ovary (CHO-K1) cells. Consecutive 5′-deletion analysis revealed the highest promoter activity in a region between by -966 and -165. DNasel footprint analysis revealed seven protected regions and electrophoretic mobility shift, super-shift and competition assays identified individual DNA-protein complexes capable of binding Sp1, estrogen receptor (ER)α, glucocorticoid receptor and CCAAT enhancer binding protein (C/EBP)γ transcription factors. Site-directed mutagenesis identified an individual Sp1 motif that plays a major role in activation of the APJR promoter and also demonstrated constitutive transcriptional regulation of the promoter by estrogen and glucocorticoid receptors. Promoter regulation by the cAMP-dependent signal cascade was also shown.
ASJC Scopus subject areas
- Molecular Biology