A Novel Type of Retinoic Acid Response Element in the Second Intron of the Mouse H2Kb Gene is Activated by the RAR/RXR Heterodimer

Abstract

We have identified and characterized a novel retinoic acid (RA) response element (Hi-RARE) in the second intron of the mouse major histocompatibility H2Kb gene. The Hi-RARE sequence is conserved in all mouse classical and Q class 1 genes, in MHC class 1 genes of the rat, Rhesus macaque, cat and in the vast majority of human classical and non-classical class 1 genes. The Hi-RARE sequence lies within a regulatory element responsible for constitutive expression of a 5' enhancerless H2Kb gene in the Ltk-fibroblasts. Hi-RARE consists of two inverted palindromic RARE consensus sites (5'-PuGGTCA-3') separated by an 8 nt spacer. Mutational analysis revealed that both inverted palindromic hexanucleotide motifs are indispensable functional sites for the 9-cis RA response. The Hi-RARE sequence confers 9-cis RA inducibility to a heterologous promoter. The inducibility is further augmented in embryonal carcinoma cells by the expression of recombinant retinoic acid receptors (PARs) and the retinoid X receptors (RXRs). In vitro, the recombinant RAR/RXR heterodimer creates DNA-protein complex with the Hi-RARE sequence. Treatment of P19 embryonal carcinoma cells with 9C-RA induces the Hi-RARE binding activity of nuclear proteins that proved to be RAR (or RAR-Like)/RXR heterodimer. Thus the Hi-RARE represents a new type of RA response element with a role in the modulation of the expression of MHC class 1 family genes.

Normalizing Microbiota-Induced Retinoic Acid Deficiency Stimulates Protective CD8 + T Cell-Mediated Immunity in Colorectal Cancer

“…Furthermore, using Vil1 -cre- Rara fl/fl mice we found that atRA treatment directly acts on tumor epithelial cells to upregulate MHCI expression, thereby rendering them more susceptible to killing by CD8 + cytotoxic T lymphocytes. Consistent with this mechanism, previous in vitro studies have demonstrated that MHCI is a direct transcriptional target of atRA (Balmer and Blomhoff, 2002; Jansa and Forejt, 1996; Nagata et al, 1992). Untreated Vil1 -cre- Rara fl/fl mice induced with AOM-DSS did not develop more tumors than control mice, but since mice with CAC already have dramatically reduced levels of atRA, the absence of RARα on epithelial cells likely would have had little impact on tumor burden.…”

Regulation of CD8+ T cell functions by RARγ

“…A novel RARE has been identified in the downstream responsive element of the mouse H2Kb gene and found to be highly conserved in MHC class I genes [49]. The outer repeat sequences are present and unmutated in all 16 classical MHC class I genes in mice, and the intact RARE is also conserved in other mammalian species [49].…”

“…The outer repeat sequences are present and unmutated in all 16 classical MHC class I genes in mice, and the intact RARE is also conserved in other mammalian species [49]. …”

The Inverted CCAAT Motif is an Indispensable Element of the Enhancer B of the Mouse Major Histocompatibility IH2-KbGene

“…The extracts were stored at 280°C. The EMSA experiments were performed as described (Jansa and Forejt, 1996), with small modifications. Briefly, DNA fragments were end-labeled by filling-in with [a-32 P]dATP using Klenow (Fig.…”