Cj. Haycraft et al., The C-elegans homolog of the murine cystic kidney disease gene Tg737 functions in a ciliogenic pathway and is disrupted in osm-5 mutant worms, DEVELOPMENT, 128(9), 2001, pp. 1493-1505
Cilia and flagella are important organelles involved in diverse functions s
uch as fluid and cell movement, sensory perception and embryonic patterning
. They are devoid of protein synthesis, thus their formation and maintenanc
e requires the movement of protein complexes from the cytoplasm into the ci
lium and flagellum axoneme by intraflagellar transport (IFT), a conserved p
rocess common to all ciliated or flagellated eukaryotic cells. We report th
at mutations in the Caenorhabditis elegans gene Y41g9a.1 are responsible fo
r the ciliary defects in osm-5 mutant worms. This was confirmed by transgen
ic rescue of osm-5(p813) mutants using the wild-type Y41g9a.1 gene, osm-5 e
ncodes a tetratricopeptide repeat (TPR)-containing protein that is the homo
log of murine polaris (Tg737), a protein associated with cystic kidney dise
ase and left-right axis patterning defects in the mouse, osm-5 is expressed
in ciliated sensory neurons in C, elegans and its expression is regulated
by DAF-19, an RFX-type transcription factor that governs the expression of
other genes involved in cilia formation in the worm. Similar to murine pola
ris, the OSM-5 protein was found to concentrate at the cilium base and with
in the cilium axoneme as shown by an OSM-5::GFP translational fusion and im
munofluorescence. Furthermore, time-lapse imaging of OSM-5::GFP fusion prot
ein shows fluorescent particle migration within the cilia, Overall, the dat
a support a crucial role for osm-5 in a conserved ciliogenic pathway, most
likely as a component of the IFT process.