Widely Spaced, Directly Repeated PuGGTCA Elements Act as Promiscuous Enhancers for Different Classes of Nuclear Receptors

Abstract

We describe here a novel class of cis-acting response elements for retinoid, vitamin D, and estrogen receptors which are widely spaced (10 to 200 bp) direct repeats (DRs) of the canonical 5-AGGTCA half-site recognition motif (DR10 to DR200). In contrast to the specificity previously observed with shortly spaced DRs (DR1 to DR5), the different receptors bind promiscuously to these novel elements to activate transcription in the presence of retinoic acid (RA), vitamin D, or estrogen. The greatest RA-dependent transactivation, seen with DR15, was similar to that observed with the canonical DR5. Both RA receptors and retinoid X receptors contribute to transactivation through widely spaced DR elements. With the estrogen receptor, DR15 was one-third as efficient as the classical palindromic response element. A further increase of spacer lengths progressively decreased the efficiency of transactivation. No transactivation was seen with widely spaced DRs when the thyroid and retinoid X receptors were coexpressed in the presence of their ligands. The progesterone receptor was also unable to transactivate through a DR10 element composed of its cognate binding motifs. These results considerably extend the response element repertoire of nuclear receptors and suggest the existence of promiscuous transcriptional regulation through common response elements, as well as the possibility of receptor ''cross-talk.''The members of the superfamily of nuclear receptors for steroid/thyroid hormones, vitamin D, and retinoic acids (RAs) are known to act as ligand-inducible transcriptional trans regulators by binding to cognate cis-acting regulatory elements referred to as ligand response elements (for reviews, see references 4, 8, 14, 18-20, 22, 35, 39, and 58). In general, ligand response elements are composed of distinct arrangements of the core motif 5Ј-PuG[G/T][T/A]CA-3Ј or closely related sequences, but some families of receptors exhibit distinct nucleotide preferences for a given position. For example, all steroid receptors require a G in position 3, while RA receptors (RARs), retinoid X receptors (RXRs), and thyroid hormone receptors (TRs) have a preference for G over T at this position. In contrast to the estrogen receptor (ER), which requires a T at position 4, the members of the glucocorticoid receptor family (glucocorticoid, mineralocorticoid, progesterone, and androgen receptors) bind only to motifs containing an A at this position. Alterations in other positions can also result in differential recognition by the various receptors. Mutational and crystal structure analyses have shown that three amino acids in the so-called P-box of the first zinc finger in the DNA-binding domain (DBD) are critically involved in the recognition of the core motif (10, 41, 43, 52, 55; for recent reviews, see references 18 and 19).In addition to receptor-specific differences in the recognition of the precise sequence of the core motif, specific binding of receptors also results from distinct arrangements of the repeated motifs. Steroid receptors ...

Regulation of Vascular Endothelial Growth Factor D by Orphan Receptors Hepatocyte Nuclear Factor-4α and Chicken Ovalbumin Upstream Promoter Transcription Factors 1 and 2

“…3). Previous studies showed that DR elements can bind nuclear receptors without showing responsiveness toward corresponding receptor agonists (38). In line with this observation, we detected binding of PPARg, RARg, and RXRa to the vegf-D DR element, whereas application of appropriate agonists (38).…”

“…Previous studies showed that DR elements can bind nuclear receptors without showing responsiveness toward corresponding receptor agonists (38). In line with this observation, we detected binding of PPARg, RARg, and RXRa to the vegf-D DR element, whereas application of appropriate agonists (38). Alternatively, such effects are due to the lack of transcriptional cofactors required for the inducibility of a given complex forming at a DR element (38).…”

Steroid hormones modulate H19 gene expression in both mammary gland and uterus

“…The H19 promoter is devoid of canonical estrogen responsive elements, but exhibits several consensual or degenerated half-sites. Some studies have shown that the estrogen receptor can bind various direct or inverted repeats of the ERE half-sites (Kato et al, 1995;Aumais et al, 1996), so ERa could act on H19 promoter by a direct manner too.…”

Induction of Hsp22 (HspB8) by estrogen and the metalloestrogen cadmium in estrogen receptor– positive breast cancer cells

“…Interestingly, the upstream ERE 1/2 is embedded in a putative retinoid X receptor ␥ (RXR␥) binding site. Similarly extended 5Ј-(G/A)GGTCA-3Ј sites were shown to represent common response elements for nuclear receptors with P boxes homologous to that of the ER, including RXRs (Kato et al 1995). In addition, the proximal promoter contains the common promoter elements CAAT box and TATA box, and 2 perfect palindromic putative heat shock elements (consensus sequence 5Ј-GAANNTTC-3Ј) that could account for the heat inducibility reported for Hsp22 (Chowdary et al 2004).…”