Lampen A, Meyer S, Nau H
Zentrumsabteilung für Lebensmitteltoxikologie, Tierärztliche Hochschule Hannover, Bischofsholer Damm 15, D-30173, Hannover, Germany.
Biochim Biophys Acta. 2001 Oct 31;1521(1-3):97-106. doi: 10.1016/s0167-4781(01)00305-0.
Retinoids are essential for growth and cell differentiation of epithelial tissues. The effects of the food compounds phytol, the phytol metabolite phytanic acid, and the fatty acid docosahexaenoic acid (DHA) on the retinoid signaling pathway in intestinal cells were studied. Phytol inhibited the formation of all-trans-retinoic acid (RA) from dietary retinol in intestinal cells. Phytanic acid, a known retinoic X receptor (RXRalpha) and peroxisome proliferator activating receptor (PPARalpha) activator, also activated PPARdelta, and to a lesser degree PPARgamma, in a transactivation assay. Phytanic acid had no effect on intestinal RA hydroxylase CYP26 (also named P450RAI) gene expression and metabolism of all-trans-RA in intestinal Caco-2 cells. However, in combination with retinoic acid receptor (RAR)-ligands (all-trans-RA or synthetic Am580) phytanic acid enhanced the induction of CYP26 and RA-metabolism in comparison to treatments with all-trans-RA or Am580 alone. Also treatment with DHA did not affect CYP26 gene expression and RA-metabolism but cotreatment of the cells with DHA and all-trans-RA or Am580 enhanced the induction of CYP26, in comparison to the induction caused by all-trans-RA or Am580 alone. This study indicates that food compounds such as phytanic acid and DHA that are RXR-agonists and have an impact on intestinal CYP26 gene expression and metabolism of all-trans-RA in intestinal cells.
维甲酸对于上皮组织的生长和细胞分化至关重要。研究了食物化合物叶绿醇、叶绿醇代谢产物植烷酸以及脂肪酸二十二碳六烯酸（DHA）对肠道细胞中维甲酸信号通路的影响。叶绿醇抑制肠道细胞中膳食视黄醇转化为全反式视黄酸（RA）。植烷酸是一种已知的视黄酸X受体（RXRα）和过氧化物酶体增殖物激活受体（PPARα）激活剂，在反式激活试验中也激活了PPARδ，并在较小程度上激活了PPARγ。植烷酸对肠道RA羟化酶CYP26（也称为P450RAI）基因表达以及肠道Caco-2细胞中全反式RA的代谢没有影响。然而，与单独使用全反式RA或合成的Am580处理相比，植烷酸与视黄酸受体（RAR）配体（全反式RA或合成的Am580）联合使用时增强了CYP26的诱导和RA代谢。同样，DHA处理也不影响CYP26基因表达和RA代谢，但与单独使用全反式RA或Am580诱导相比，DHA与全反式RA或Am580联合处理细胞增强了CYP26的诱导。这项研究表明，植烷酸和DHA等食物化合物作为RXR激动剂，对肠道细胞中CYP26基因表达和全反式RA的代谢有影响。
