[
International Worm Meeting,
2005]
Cilia are important structures that function in a variety of ways including sensory perception, cell and fluid motility, and embryonic patterning. Intraflagellar Transport (IFT) is a mechanism by which proteins necessary for cilia formation and maintenance are assembled into large rafts at the base of the cilia and are carried along the cilium axoneme in anterograde and retrograde directions by motor proteins. The importance of IFT and its role in ciliogenesis is evident because mutations in known IFT genes can lead to loss of motility and mating in Chlamydomonas, defects in sensory functions and mating behavior in C. elegans, and systemic diseases such as polycystic kidney disease and embryonic patterning defects in the mouse. Several characterized IFT genes in C. elegans have previously been shown to be regulated by a common transcription factor, DAF-19, which binds to a sequence known as an X-box in the promoters of these IFT genes. Based on the presence of this X-box, we have identified a novel cilia protein, T28F3.6, that shares significant homology with members of the Rab family of proteins which are known to be involved in protein trafficking. In addition, this protein is homologous to the RabL5 protein that is conserved among ciliated eukaryotes including human, mouse, and Drosophila. We have found that T28F3.6::GFP is localized to cilia in C. elegans and moves along the cilium axoneme similar to other IFT proteins. Furthermore, mutation of a single amino acid believed to be involved in GTP binding causes delocalization of the protein throughout the ciliated sensory neurons. Also, analysis of T28F3.6::GFP in several known cilia mutants shows that T28F3.6::GFP remains localized to cilia despite loss of other IFT proteins. Preliminary results show that T28F3.6 is a GTP binding protein. We are continuing to explore this binding by creating point mutations in the conserved GTP binding domains. Finally, we have obtained two C. elegans mutants in T28F3.6 and found that the cilia are properly formed in both strains. Therefore, we are continuing to analyze these mutants for IFT and cilia associated sensory phenotypes as a way to discern the specific role of T28F3.6 in cilia.