Retinoic Acid Inducibility of the Human PDGF-A Gene Is Mediated by 5′-Distal DNA Motifs That Overlap With Basal Enhancer and Vitamin D Response Elements

Abstract

Retinoic acid (RA) upregulates expression of PDGF ligands and receptors in neonatal rat lung fibroblasts, a process likely to promote maturation of the lung alveolus and possibly microstructures of other organs. A mutational analysis of the gene encoding the PDGF-A ligand has identified a complex retinoic acid response element (RARE) located far upstream of the transcription start site, in a 5'-distal enhanceosome region previously shown to harbor basal and vitamin D-inducible enhancer activity. Maximal RA responsiveness (fourfold) was conferred by nucleotide sequence located between -7064 and -6787, with a variety of deletion and point mutations revealing the importance of at least three nuclear receptor half-sites within the enhancer region (-6851 to -6824), as well as nucleotides located further upstream. Recombinant human retinoic acid receptor/retinoid-X receptor heterodimers bound with high affinity and sequence specificity to multiple regions within the RARE, as demonstrated by electrophoretic mobility shift and DNase I footprinting assays. The addition of RARE activity to previously described functions of the 5'-distal enhanceosome underscores the importance of this region as a key integration point for regulatory control of PDGF-A expression.

A Genome-Wide Search for Gene-Environment Effects in Isolated Cleft Lip with or without Cleft Palate Triads Points to an Interaction between Maternal Periconceptional Vitamin Use and Variants in ESRRG

“…Retinoic acid, on the other hand, inhibits proliferation of embryonic palatal shelves in mice by downregulating Pdgfc activity (Han et al, 2006 ). Pedigo et al ( 2007 ) later reported the location of a complex retinoic acid response element in a region upstream of the transcription start site of PDGFA that was previously shown to harbor basal and vitamin D-inducible enhancer activity, which lends support to the connections seen between these entities in Figure 9 .…”

PDGF-A promoter and enhancer elements provide efficient and selective antineoplastic gene therapy in multiple cancer types

“…Of additional relevance is a complex enhanceosome located within the 5’-distal region of the PDGF-A gene (−7294 to −6787), which is highly activated in a number of transformed cell lines 15. This region contains a potent 66 bp enhancer (ACE66) which contains four tandemly arranged half-sites for binding of nuclear receptors, a ternary complex factor motif and overlapping response elements for vitamin D16 and retinoic acid 17. A high degree of transcriptional synergism is obtained with three directly repeated copies of the ACE66 element, ranging from 30-fold enhancement in HepG2 (hepatoma) and U2-OS (osteosarcoma) cells to 200-fold in JEG-3 and other choriocarcinoma lines.…”