Synthesis and activity of dafachronic acid ligands for the C. elegans DAF-12 nuclear hormone receptor

Mol Endocrinol. 2009 May;23(5):640-8. doi: 10.1210/me.2008-0415. Epub 2009 Feb 5.


The nuclear hormone receptor DAF-12 from Caenorhabditis elegans is activated by dafachronic acids, which derive from sterols upon oxidation by DAF-9, a cytochrome P450. DAF-12 activation is a critical checkpoint in C. elegans for acquisition of reproductive competence and for entry into adulthood rather than dauer diapause. Previous studies implicated the (25S)-Delta(7)-dafachronic acid isomer as the most potent compound, but the (25S)-Delta(4)-isomer was also identified as an activator of DAF-12. To explore the tolerance of DAF-12 for structural variations in the ligand and to enable further studies requiring large amounts of ligands for DAF-12 and homologs in other nematodes, we synthesized (25R)- and (25S)-isomers of five dafachronic acids differing in A/B-ring configurations. Both the (25S)- and (25R)-Delta(7)-dafachronic acids are potent transcriptional activators in a Gal4-transactivation assay using HEK-293 cells, with EC(50) values of 23 and 33 nm, respectively, as are (25S)- and (25R)-Delta(4)-dafachronic acids, with EC(50) values of 23 and 66 nm, respectively. The (25S)- and (25R)-Delta(5)-isomers were much less potent, with EC(50) values approaching 1000 nm, and saturated 5alpha- and 5beta-dafachronic acids showed mostly intermediate potencies. Rescue assays using daf- 9-null mutants confirmed the results from transactivation experiments, but this in vivo assay accentuated the greater potencies of the (25S)-epimers, particularly for the (25S)-Delta(7)-isomer. We conclude that DAF-12 accommodates a large range of structural variation in ligand geometry, but (25S)-Delta(7)-dafachronic acid is the most potent and probably biologically relevant isomer. Potency derives more from the A/B-ring configuration than from the stereochemistry at C-25.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caenorhabditis elegans Proteins / metabolism*
  • Cell Line
  • Cholestenes / chemical synthesis*
  • Cholestenes / chemistry
  • Cholestenes / metabolism*
  • Humans
  • Isomerism
  • Ligands
  • Molecular Structure
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Trans-Activators / chemical synthesis
  • Trans-Activators / chemistry
  • Trans-Activators / metabolism


  • Caenorhabditis elegans Proteins
  • Cholestenes
  • DAF-12 protein, C elegans
  • Ligands
  • Receptors, Cytoplasmic and Nuclear
  • Trans-Activators
  • dafachronic acid