Sp1 dependence of natriuretic peptide receptor a gene transcription in rataortic smooth muscle cells

The atrial natriuretic peptide receptor (NPR-A) Is expressed in smooth musc le cells of the vasculature, where it is thought to signal the vasodilatory properties of the peptide. Despite its important role as a regulator of ca rdiovascular homeostasis, relatively little is known of the genomic factors governing expression of this gene. We show here that NPR-A promoter activi ty is reduced by 50-75% when any of three GC-rich sites are mutated. Simult aneous mutation of all three leads to a >90% reduction in NPR-A promoter ac tivity. Transfection of wild-type, but not mutant, decoy oliogonucleotides encoding any one of the sites reduces NPR-A activity, presumably reflecting competition for a common transcription factor. Gel shift analyses show tha t each of the wild-type, but not the mutant, sites interferes with the form ation of selected DNA-protein complexes on the other sites. These complexes share similar electrophoretic mobility. immunoperturbation studies show th at one of these shared complexes contains Spl, whereas two others contain S p3. Overexpression of either Spl or Sp3 in a cell type containing very low levels of these transcription factors (i.e. Drosophila Schneider cells) lea ds to induction of the wild-type, but not the mutant, NPR-A promoter. The d ata suggest that the Spl family of transcription factors plays a central ro le in NPR-A gene transcription. The association of Spl family members with transcriptional regulation of a number of genes involved in hemodynamic con trol will be discussed.