The C. elegans gene
rol-3 has been recently identified as a member of the receptor tyrosine kinase family.
rol-3 has the typical conserved domains of a receptor tyrosine kinase and shows 56% sequence similarity to the human proto- onogene , c-ROS. Homozygous mutant worms are identified as having an abnormally left-hand twisted cuticle, body muscle, gut and ventral nerve cord, and are seen to display left hand rotation during movement. Using a variety of genetic and biochemical methods, we are characterising the
rol-3 signalling pathway in C. elegans . 11 alleles of
rol-3 , including one temperature sensitive mutation (
s1040ts ), have been previously isolated in our lab. 9 of these alleles are being sequenced to identify the molecular basis of the lesions. These alleles all exhibit a recessive early to mid larval lethal phenotype suggesting an early, essential activity for
rol-3 . A
rol-3 promoter::GFP fusion construct was injected into wild type worms and GFP expression is strongly observed in hypodermis and body wall muscle throughout embryogenesis. This expression drops off during early larval development in agreement with the expression pattern predicted using available SAGE data. Temperature shift analysis of the
s1040ts allele also suggests an essential requirement for
rol-3 between 15-35 hours post egg-lay. Weak GFP expression is also observed in the adult vulva and body wall muscle. To identify components of the
rol-3 pathway I have undertaken an RNAi screen using the
s1040ts allele of
rol-3 looking for enhancement of the hypomorphic phenotype. RNAi candidates include conserved members of RTK signalling pathways such as the Rho family GTPases and their interacting proteins. Two suppressors of
rol-3 lethality have been identified,
srl-1 and
srl-2 ( S upp of R oller L ethality). Mapping of the genetic positions of these suppressors places
srl-1 onto chromosome II and
srl-2 onto a position of LGIII in the region of two overlapping cosmids B0361 and F56C9, current work is now directed at identifying these genes and characterising their molecular nature.