A Retinoic Acid Receptor-Specific Element Controls the Retinoic Acid Receptor-β Promoter

Abstract

The morphogen retinoic acid (RA) regulates gene transcription by interacting with specific nuclear receptors that recognize DNA sequences near responsive promoters. While much has recently been learned about the nuclear receptor proteins, little is known about the genes that are directly regulated by RA and their cis-acting response elements recognized by these receptors. Here we have analyzed the RA receptor-beta (RAR beta) gene promoter that is controlled by RA. We find that a RA-responsive element (RARE) is located adjacent to the TATA box. The RARE shows a direct repeat symmetry which is essential for its function. While thyroid hormone-responsive elements can also function as RAR response elements, we show here that this RARE is activated by endogenous RARs and RAR beta, but cannot be regulated by thyroid hormone receptors and other known nuclear receptors. In addition, we find that RAR gamma is a poor activator of this RARE. However, the response element is bound with high affinity by both RAR beta and RAR gamma as well as by thyroid hormone receptors. Thus, interaction between specific response elements and receptors is insufficient for gene activation.

Functional specificity of the two retinoic acid receptor RAR and RXR families in myogenesis

“…Before using these mutant receptors (designated in this work as dnRAR and dnRXR) to block the action of endogenous retinoic acid receptors in myogenesis, we ®rst tested their dominant negative activity following transient transfection into C2 myogenic cells. For this purpose, C2 cells were cotransfected with the expression vectors encoding dnRAR or dnRXR receptors (pSG5-dnRAR or pSG5-dnRXR) and a reporter construct containing the classical retinoic-acid response element (RAREb) (de The et al, 1990;Ho man et al, 1990) in front of the thymidine kinase promoter linked to the chloramphenicol-acetyl transferase gene (tk-CAT) (see Materials and methods) ( Figure 1). As shown in Figure 1, treatment of pSG5-transfected C2 cells with RA increased RAREb-tk-CAT reporter activity by 2 ± 3-fold.…”

“…Furthermore, the RAREb response element has been described and characterized in the regulatory region of RARb gene (de The et al, 1990;Ho man et al, 1990). In C2-neo control cells, RARb mRNA was undetectable before RA-treatment but was strongly We next compared the RA-regulation of MyoD and myogenin gene expression over a time course period of RA treatment for C2-neo, C2-dnRAR1 and C2-dnRXR1 cells.…”

Ubiquitinated or sumoylated retinoic acid receptor alpha determines its characteristic and interacting model with retinoid X receptor alpha in gastric and breast cancer cells

“…The reporter RARE ( retinoic acid response element) was linked with a thymidine kinase promoter ( RARE-tk-CAT) (Hoffmann et al 1990). The RAR expression vector used has been described elsewhere (Wu et al 1997a,b).…”

Constitutive Activation of Retinoic Acid Receptor β2 Promoter by Orphan Nuclear Receptor TR2

“…These include, among others, an RA-responding DR5, a cyclic AMP-response element (CRE), and a TATA box (28). The DR5 is responsible for a rapid and potent RA induction, mediated by holo-RAR/RXR binding (21,23,29). The biological effects of cAMP has also been confirmed in the P19 culture model (28).…”

“…Like the studies of several other orphan receptors COUP-TF, nerve growth factor-1B, Dax1, and hepatocyte nulcear factor-4 (37-40), previous studies of TR2 in different labs have utilized RA response element-and other hormone response elementcontaining reporters to examine its biological activities (5,24,25,28,29). The finding that apo-TR2 is able to bind to this DR5 with a high affinity (an estimated K d 7.4 nM) in the absence of putative ligands (12,16,17) has prompted us to examine the effect of TR2 expression on the endogenous RAR ␤2 gene activity in the absence of RA.…”