An autosomal recessive polycystic kidney disease gene homolog is involved in intraflagellar transport in C. elegans ciliated sensory neurons

In this report, we show that the Caenorhabditis elegans gene osm-5 is homologous to the Chlamydomonas gene IFT88 and the mouse autosomal recessive polycystic kidney disease (ARPKD) gene, Tg737. The function of this ARPKD gene may be evolutionarily conserved: mutations result in defective ciliogenesis in worms 1], algae 2], and mice 2, 3]. Intraflagellar transport (IFT) is essential for the development and maintenance of motile and sensory cilia 4]. The biochemically isolated IFT particle from Chlamydomonas flagella is composed of 16 polypeptides in one of two Complexes (A and B) 5, 6] whose movement is powered by kinesin II (anterograde) and cytoplasmic dynein (retrograde) 7-9]. We demonstrate that OSM-5 (a Complex B polypeptide), DAF-10 and CHE-11 (two Complex A polypeptides), and CHE-2 10], a previously uncategorized IFT polypeptide, all move at the same rate in C. elegans sensory cilia. In the absence of osm-5, the C. elegans autosomal dominant PKD (ADPKD) gene products 11] accumulate in stunted cilia, suggesting that abnormal or lack of cilia or defects in IFT may result in diseases such as polycystic kidney disease (PKD).