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.
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.
Pedigo
Nancy G
NG
Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, Lexington, KY 40536-0298, USA.
Zhang
Hongxing
H
Mishra
Anjali
A
McCorkle
Joseph R
JR
Ormerod
Angela K
AK
Kaetzel
David M
DM
D024506:5' Flanking Region; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004742:Enhancer Elements, Genetic; D017930:Genes, Reporter; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D010982:Platelet-Derived Growth Factor / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020218:Response Elements; D000072482:Retinoic Acid Receptor alpha; D047490:Retinoid X Receptor alpha / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology*; D014807:Vitamin D / Q000235:genetics*
D010982:Platelet-Derived Growth Factor; C000607071:RARA protein, human; D012333:RNA, Messenger; C000607073:Rara protein, rat; D018168:Receptors, Retinoic Acid; D011994:Recombinant Proteins; D000072482:Retinoic Acid Receptor alpha; D047490:Retinoid X Receptor alpha; C075278:platelet-derived growth factor A; D014807:Vitamin D; D014212:Tretinoin; D004247:DNA; D008156:Luciferases