Phytol metabolites are circulating dietary factors that activate the nuclear receptor RXR.

Published

Journal Article

RXR is a nuclear receptor that plays a central role in cell signaling by pairing with a host of other receptors. Previously, 9-cis-retinoic acid (9cRA) was defined as a potent RXR activator. Here we describe a unique RXR effector identified from organic extracts of bovine serum by following RXR-dependent transcriptional activity. Structural analyses of material in active fractions pointed to the saturated diterpenoid phytanic acid, which induced RXR-dependent transcription at concentrations between 4 and 64 microM. Although 200 times more potent than phytanic acid, 9cRA was undetectable in equivalent amounts of extract and cannot be present at a concentration that could account for the activity. Phytanic acid, another phytol metabolite, was synthesized and stimulated RXR with a potency and efficacy similar to phytanic acid. These metabolites specifically displaced [3H]-9cRA from RXR with Ki values of 4 microM, indicating that their transcriptional effects are mediated by direct receptor interactions. Phytol metabolites are compelling candidates for physiological effectors, because their RXR binding affinities and activation potencies match their micromolar circulating concentrations. Given their exclusive dietary origin, these chlorophyll metabolites may represent essential nutrients that coordinate cellular metabolism through RXR-dependent signaling pathways.

Full Text

Duke Authors

Cited Authors

  • Kitareewan, S; Burka, LT; Tomer, KB; Parker, CE; Deterding, LJ; Stevens, RD; Forman, BM; Mais, DE; Heyman, RA; McMorris, T; Weinberger, C

Published Date

  • August 1996

Published In

Volume / Issue

  • 7 / 8

Start / End Page

  • 1153 - 1166

PubMed ID

  • 8856661

Pubmed Central ID

  • 8856661

International Standard Serial Number (ISSN)

  • 1059-1524

Digital Object Identifier (DOI)

  • 10.1091/mbc.7.8.1153

Language

  • eng

Conference Location

  • United States