CYP26A1 gene promoter is a useful tool for reporting RAR-mediated retinoid activity

Abstract

Of numerous genes regulated by retinoic acid (RA), CYP26A1 is the most inducible gene by RA. In this study, we have used a shortened construct form, E4, of the CYP26A1 gene promoter, in a promoter-less vector with either luciferase or red fluorescent protein (RFP) as the reporter gene and have tested its responses to retinoids in transfected HepG2 and HEK293T cells. The promoter responded linearly to a wide concentration range of RA in cells cotransfected with retinoic acid receptors. It also responded quantitatively to retinol and other retinoids. An isolated clonal line of HEK293T cells permanently transfected with the promoter driving the expression of RFP responded to both RA and retinol, and the responses could be measured by fluorescence microscopy and flow cytometry. The promoter was used to assess the retinoid activity of 3 novel synthetic retinoid analogues, as well as of the intact serum samples of rats. Among the synthetic retinoid analogues tested, EC23 is more potent than RA at lower concentrations and was more stable than RA. The retinoid activities could be measured in control rat serum samples and were increased in the serum of RA-treated rats. This system offers a biologically-based alternative to massbased retinoid analysis.

Association of CYP26C1 Promoter Hypomethylation with Small Vessel Occlusion in Korean Subjects

“…According to these studies, the expression of CYP26C1 might be regulated by RA-linked transcription factors. Taimi et al showed that RA induces CYP26C1 expression in a HPK1a cell line, and Zolfaghari et al reported that RAR-mediated signaling induces the expression of CYP26A1 (one of the CYP26 family) [16,40]. These data suggest that hypomethylation of CYP26C1 might induce its expression and might decrease regional RA, which affects the occurrence of SVO.…”

Potentiation of IL-4 Signaling by Retinoic Acid in Intestinal Epithelial Cells and Macrophages—Mechanisms and Targets

“…Another interesting observation was the induction of mRNA for CYP26A1, the enzyme responsible for ATRA catabolism and a sensitive indicator of ATRA bioactivity activity (55,56), by ATRA in THP-1 cells that were also treated with IL-4. This is in contrast to ATRA-induced CYP26A1 expression that was significantly reduced in THP-1 cells that were also treated with LPS (15).…”

Structural Fusion of Natural and Synthetic Ligand Features Boosts RXR Agonist Potency

“…Activation of full-length human RXR was studied in transiently transfected HEK293T cells using firefly luciferase reporter constructs for the RXR homodimer (DR1 response element, Addgene, Watertown, MA, plasmid #1015) and the RXR:RAR heterodimer (pGL3-RARE-luciferase, Addgene, plasmid #13458). The full-length human nuclear receptors were overexpressed using pSG5-hRXR and pcDNA3.1-hRAR (Addgene, plasmid #135397). pRL-SV40 (Promega) was cotransfected for normalization of transfection efficacy and to observe test compound toxicity.…”