Expression and function of conserved nuclear receptor genes in Caenorhabditis elegans

Abstract

The Caenorhabditis elegans genome encodes 284 nuclear receptor (NR) genes. Among these 284 NR genes are 15 genes conserved among the Metazoa. Here, we analyze the expression and function of eight heretofore uncharacterized conserved C. elegans NR genes. Reporter gene analysis demonstrates that these genes have distinct expression patterns and that a majority of the C. elegans cell types express a conserved NR gene. RNA interference with NR gene function resulted in visible phenotypes for three of the genes, revealing functions in various processes during postembryonic development. Five of the conserved NR genes are orthologs of NR genes that function during molting and metamorphosis in insects. Functional studies confirm a role for most of these 'ecdysone cascade' NR orthologs during the continuous growth and dauer molts. Transcript levels for these genes fluctuate in a reiterated pattern during the molting cycles, reminiscent of the expression hierarchy observed in the insect ecdysone response. Together, these analyses provide a foundation for further dissecting the role of NRs in nematode development as well as for evaluating conservation of NR functions among the Metazoa.

Nuclear receptor BgFTZ‐F1 regulates molting and the timing of ecdysteroid production during nymphal development in the hemimetabolous insect Blattella germanica

“…As observed in insects, expression of nhr-23 and nhr-25 mRNAs oscillates with each molting cycle (Gissendanner et al, 2004) and RNAi of both receptors at the intermolt results in a defective molt, with associated problems of cuticle shedding (Ashaina et al, 2000;Gissendanner and Sluder, 2000). However, whereas HR3 controls the expression of FTZ-F1 in insects, nhr-25 expression seems not dependent of nhr-23 (Krostrouchova et al, 2001).…”

A Mediator subunit, MDT-15, integrates regulation of fatty acid metabolism by NHR-49-dependent and -independent pathways inC. elegans

“…1). Other candidates include NHR-64 (which can bind MDT-15 in the two-hybrid assay [this study] and is expressed in the gut, among other tissues [Gissendanner et al 2004]) and SBP-1, the only C. elegans ortholog of human SREBP proteins (which regulate lipid and cholesterol metabolism and interact with Mediator [Naar et al 1999;Toth et al 2004]). In any case, our data indicate that MDT-15 controls the expression of a subset of FA-metabolism genes by interacting with multiple regulatory factors.…”

The neuroendocrine system of invertebrates: a developmental and evolutionary perspective

“…The genome of Caenorhabditis elegans contains 41 genes encoding peptide hormones, 21 of which represent FMRF-like peptides with multiple functions in neural transmission (Li et al 1999). A neuroendocrine network that has been characterized in detail in C. elegans regulates growth, metabolism, and lifespan (Kimura et al 1997, Gerisch et al 2001, Jia et al 2002, Tatar et al 2003, Gissendanner et al 2004, Kurz & Tan 2004, Mak & Ruvkun 2004. Central neurons producing insulin-like peptide act on a group of cells, among them a pair of sensory neurons and a set of epidermal cells in the head, which express a cytochrome P450 enzyme (encoded by the daf-9 gene) suspected to be involved in the synthesis of a steroid hormone.…”