Structure and expression of daf-12: a nuclear hormone receptor with three isoforms that are involved in development and aging in Caenorhabditis elegans
Mi. Snow et Pl. Larsen, Structure and expression of daf-12: a nuclear hormone receptor with three isoforms that are involved in development and aging in Caenorhabditis elegans, BBA-GENE ST, 1494(1-2), 2000, pp. 104-116
Citations number
67
Categorie Soggetti
Molecular Biology & Genetics
Journal title
BIOCHIMICA ET BIOPHYSICA ACTA-GENE STRUCTURE AND EXPRESSION
During Caenorhabditis elegans early larval development environmental condit
ions promote a cascade of signaling molecules to direct growth to the repro
ductive adult or to arrest development as a dauer larva. Two parallel chemo
sensory signal transduction pathways, one of which is transforming growth f
actor (TGF)-beta -like, converge on the daf-12 gene to regulate dauer forma
tion. A third insulin-like signaling pathway interacts with the daf-12 path
way to regulate both dauer formation and adult longevity. To further unders
tand the role of daf-12 in these processes, we have molecularly characteriz
ed this gene. We establish rescue of the mutant dauer defective phenotype w
ith a genomic clone. We show that three transcripts of different lengths, d
ue to differential splicing, are made from the daf-12 gene. The deduced pro
tein isoforms are similar to both DNA- and ligand-binding domains of nuclea
r hormone receptors. The three daf-12 transcripts are produced throughout d
evelopment and expression increases during the preparation for and executio
n of dauer formation. Analysis of various daf mutant strains suggests that
the isoform ratios of daf-12 steady-state mRNA are not changed by reduction
of function in the TGF-P and insulin signaling components of the dauer pat
hway. The daf-12 promoter directs expression of GFP in the pharynx. daf-12
is a C. elegans nuclear hormone receptor with multiple isoforms, is express
ed throughout development in distinct cells, and functions under a variety
of environmental conditions. (C) 2000 Elsevier Science B.V. All rights rese
rved.