The vitamin D receptor interacts preferentially with DRIP205-like LxxLL motifs

Abstract

The vitamin D receptor (VDR) mediates the biological actions of 1,25-dihydroxyvitamin D 3 (1,25 (OH) 2 D 3 ) through its capacity to recruit coregulatory proteins. This interaction is mediated via a coregulatory LxxLL motif. We screened a combinatorial (x) 7 LxxLL(x) 7 phage library with purified VDR to identify peptides that displayed high affinity and selectivity for VDR. These peptides contained the consensus sequence Lx E/H x H/F P L/M/I LxxLL and exhibited significant sequence similarity to the active LxxLL box found in DRIP 205 . Nearly all LxxLL peptides interacted in a ligand-dependent manner directly with human VDR. However, a pattern of selectivity of the peptides for other members of the nuclear receptor family was also observed. Interestingly, the interaction between the VDR and many of the peptides was differentially sensitive to a broad assortment of VDR ligands. Finally, several of these peptides were shown to inhibit activation of a vitamin 1,25 (OH) 2 D 3 -sensitive reporter gene. These studies suggest that the LxxLL motif can interact directly with the VDR and that this interaction is regulated by chemically diverse vitamin D ligands.

H2O2-dependent translocation of TCTP into the nucleus enables its interaction with VDR in human keratinocytes: TCTP as a further module in calcitriol signalling

“…In this context, we have proven that the VDR LBD is definitely responsible for the interaction with human TCTP and especially with TCTP domain 2 that notably contains a putative coregulatory LxxLL-like (Ile 121 -x-xIle 124 -Leu 125 ) binding motif identified through a close inspection of the helical regions of various TCTPs from known x-ray and/or NMR structures [14,34,47,48]. The general trend for LxxLL motifs (where L represents leucine and x is any AA) includes a hydrophobic AA positioned at -1 and -7, a proline at -2, an aromatic residue at -3 and glutamate at location -5, hence creating an L-x-E/H-x-H/F-P-L/M/I-L-x-x-L-L pattern [49], whereas TCTP rather comprises an M-x-G-x-A-E-Q-I 121 -x-x-I 124 -L 125 sequence in this place. Although the AA residues flanking the main core are known to be important for the recognition of selected classes of NHRs in general, their exact number and composition can vary considerably among different coactivators [47,48].…”

1,25-Dihydroxyvitamin D3 Controls a Cohort of Vitamin D Receptor Target Genes in the Proximal Intestine That Is Enriched for Calcium-regulating Components

“…Additional studies now demonstrate that the ability of the VDR, other steroid receptors of which the VDR is a member, and indeed most transcription factors to regulate gene expression involves their capacity to recruit large, highly complex molecular machines, which function at numerous levels to alter the unique restraints imposed at target gene loci by chromatin structure (36,37). This recruitment is facilitated through an interaction between the steroid-regulated activation domain of the VDR and leucine-rich LXXLL motifs that are located in at least one component of each of these coregulatory complexes (38). Most of these machines contain unique enzymatic activities that represent the cornerstone of their ability to alter the chromatin environments surrounding individual target genes (39).…”

Inhibitors for the Vitamin D Receptor–Coregulator Interaction

“…In addition, RXR-selective peptide F6 was able to inhibit VDR-mediated transcription, demonstrating transactivation between RXR and VDR. A more exhaustive phage display library identified three more LXXLL peptides (Figure 2, compounds 3,4, and 5) that not only bind VDR in a two hybrid assay but also inhibit VDR-mediated transcription when expressed in cells (34). These peptides exhibit a consensus sequence of (H/F)P(L/M)LXXLL.…”

“…SDS-PAGE demonstrated three different conformations of VDR–ZK159222 complex (69). These conformations may be responsible for the dissociation between liganded VDR and coactivators SRC1, SRC2, SCR3, and DRIP205 (34, 65). In addition, the interaction between corepressor NCoR and VDR was inhibited (63).…”