TY - JOUR

T1 - The endogenous retinoid metabolite S-4-oxo-9-cis-13,14-dihydro-retinoic acid activates retinoic acid receptor signalling both in vitro and in vivo

AU - Schuchardt, Jan Philipp

AU - Wahlström, David

AU - Rüegg, Joëlle

AU - Giese, Norbert

AU - Stefan, Madalina

AU - Hopf, Henning

AU - Pongratz, Ingemar

AU - Hakansson, Helen

AU - Eichele, Gregor

AU - Pettersson, Katarina

AU - Nau, Heinz

PY - 2009/6

Y1 - 2009/6

N2 - Retinoic acid receptor (RAR) and retinoid X receptor are ligand-induced transcription factors that belong to the nuclear receptor family. The receptors are activated by small hydrophobic compounds, such as all-trans-retinoic acid and 9-cis-retinoic acid, respectively. Interestingly, these receptors are also targets for a number of exogenous compounds. In this study, we characterized the biological activity of the 9-cis-substituted retinoic acid metabolite, S-4-oxo-9-cis-13,14-dihydro-retinoic acid (S-4o9cDH-RA). The endogenous levels of this metabolite in wild-type mice and rats were found to be higher than those of all-trans-retinoic acid, especially in the liver. Using cell-based luciferase reporter systems, we showed that S-4o9cDH-RA activates the transcription of retinoic acid response element-containing genes in several cell types, both from a simple 2xDR5 element and from the promoter of the natural retinoid target gene RAR. In addition, quantitative RT-PCR analysis demonstrated that S-4o9cDH-RA treatment significantly increases the endogenous mRNA levels of the RAR target gene RAR. Utilizing a limited proteolytic digestion assay, we showed that S-4o9cDH-RA induces conformational changes to both RAR and RARin the same manner as does all-trans-retinoic acid, suggesting that S-4o9cDH-RA is indeed an endogenous ligand for these receptors. These in vitro results were corroborated in an in vivo system, where S-4o9cDH-RA induced morphological changes similar to those of all-trans-retinoic acid in the developing chicken wing bud. When locally applied to the wing bud, S-4o9cDH-RA induced digit pattern duplications in a dose-dependent fashion. The results illustrate that S-4o9cDH-RA closely mimics all-trans-retinoic acid with regard to pattern respecification. Finally, using quantitative RT-PCR analysis, we showed that S-4o9cDH-RA induces the transcription of several retinoic acid-regulated genes in chick wing buds, including Hoxb8, RAR, shh, Cyp26 and bmp2. Although S-4o9cDH-RA was less potent when compared with all-trans-retinoic acid, the findings clearly demonstrate that S-4o9cDH-RA has the capacity to bind and activate nuclear retinoid receptors and regulate gene transcription both in vitro and in vivo.

AB - Retinoic acid receptor (RAR) and retinoid X receptor are ligand-induced transcription factors that belong to the nuclear receptor family. The receptors are activated by small hydrophobic compounds, such as all-trans-retinoic acid and 9-cis-retinoic acid, respectively. Interestingly, these receptors are also targets for a number of exogenous compounds. In this study, we characterized the biological activity of the 9-cis-substituted retinoic acid metabolite, S-4-oxo-9-cis-13,14-dihydro-retinoic acid (S-4o9cDH-RA). The endogenous levels of this metabolite in wild-type mice and rats were found to be higher than those of all-trans-retinoic acid, especially in the liver. Using cell-based luciferase reporter systems, we showed that S-4o9cDH-RA activates the transcription of retinoic acid response element-containing genes in several cell types, both from a simple 2xDR5 element and from the promoter of the natural retinoid target gene RAR. In addition, quantitative RT-PCR analysis demonstrated that S-4o9cDH-RA treatment significantly increases the endogenous mRNA levels of the RAR target gene RAR. Utilizing a limited proteolytic digestion assay, we showed that S-4o9cDH-RA induces conformational changes to both RAR and RARin the same manner as does all-trans-retinoic acid, suggesting that S-4o9cDH-RA is indeed an endogenous ligand for these receptors. These in vitro results were corroborated in an in vivo system, where S-4o9cDH-RA induced morphological changes similar to those of all-trans-retinoic acid in the developing chicken wing bud. When locally applied to the wing bud, S-4o9cDH-RA induced digit pattern duplications in a dose-dependent fashion. The results illustrate that S-4o9cDH-RA closely mimics all-trans-retinoic acid with regard to pattern respecification. Finally, using quantitative RT-PCR analysis, we showed that S-4o9cDH-RA induces the transcription of several retinoic acid-regulated genes in chick wing buds, including Hoxb8, RAR, shh, Cyp26 and bmp2. Although S-4o9cDH-RA was less potent when compared with all-trans-retinoic acid, the findings clearly demonstrate that S-4o9cDH-RA has the capacity to bind and activate nuclear retinoid receptors and regulate gene transcription both in vitro and in vivo.

KW - Dihydro-retinoic acid metabolite

KW - Gene expression

KW - Novel retinoid metabolites

KW - RAR

KW - Vitamin A metabolism

UR - http://www.scopus.com/inward/record.url?scp=65549160442&partnerID=8YFLogxK

U2 - 10.1111/j.1742-4658.2009.07023.x

DO - 10.1111/j.1742-4658.2009.07023.x

M3 - Article

C2 - 19490107

AN - SCOPUS:65549160442

VL - 276

SP - 3043

EP - 3059

JO - FEBS Journal

JF - FEBS Journal

SN - 1742-464X

IS - 11

ER -