The conserved nuclear receptor Ftz-F1 is required for embryogenesis, moulting and reproduction in Caenorhabditis elegans.
BACKGROUND
Nuclear receptors are essential players in the development of all metazoans. The nematode Caenorhabditis elegans possesses more than 200 putative nuclear receptor genes, several times more than the number known in any other organism. Very few of these transcription factors are conserved with components of the steroid response pathways in vertebrates and arthropods. Ftz-F1, one of the evolutionarily oldest nuclear receptor types, is required for steroidogenesis and sexual differentiation in mice and for segmentation and metamorphosis in Drosophila.


RESULTS
We employed two complementary approaches, direct mutagenesis and RNA interference, to explore the role of nhr-25, a C. elegans ortholog of Ftz-F1. Deletion mutants show that nhr-25 is essential for embryogenesis. RNA interference reveals additional requirements throughout the postembryonic life, namely in moulting and differentiation of the gonad and vulva. All these defects are consistent with the nhr-25 expression pattern, determined by in situ hybridization and GFP reporter activity.


CONCLUSIONS
Our data link the C. elegans Ftz-F1 ortholog with a number of developmental processes. Significantly, its role in the periodical replacement of cuticle (moulting) appears to be evolutionarily shared with insects and thus supports the monophyletic origin of moulting.
Asahina
M
M
Department of Developmental Genetics, National Institute of Genetics, Mishima, Shizuoka-ken 411-8540, Japan.
Ishihara
T
T
Jindra
M
M
Kohara
Y
Y
Katsura
I
I
Hirose
S
S
D000818:Animals; D019521:Body Patterning; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D017403:In Situ Hybridization; D007814:Larva; D018978:Molting; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012313:RNA / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear; D012098:Reproduction; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C486359:nuclear hormone receptor NHR-25, C elegans; D012313:RNA