The planar cell polarity (PCP) pathway is responsible for organizing cell polarity in the plane of the epithelium. We have recently shown that the core PCP pathway components Van Gogh (
vang-1), Prickle (
prkl-1), and Dishevelled (
dsh-1) are required in a subset of peripheral motor neurons (VC neurons) to restrict neurite emergence to a specific tissue axis. In loss-of-function mutants, VC4 and VC5 neurons display ectopic neurites that extend abnormally along the anteroposterior (AP) body axis. The
unc-4 promoter is expressed in the VA, DA and VC motor neurons.
unc-4 driven over-expression of PRKL-1 in the VC neurons is sufficient to suppress neurite growth. These transgenic animals also displayed backwards locomotion impairment; a movement controlled by the VA and DA neurons. This inability to move backwards is suppressed by
vang-1 null mutants, which are known to interact with
prkl-1 in the PCP pathway. We used these observations as the basis of a genetic screen to identify other suppressors that can restore backwards locomotion. Our preliminary findings include the identification of several suppressor mutants including at least 8 new alleles of
vang-1 and at least one allele of
fntb-1, the beta subunit of farnesyltransferase. Farnesyltransferases post translationally modifies proteins by attaching a 15-carbon isoprenoid lipid, farnesyl, to the cysteine residue of a C-terminal CAAX motif. The addition of a farnesyl group facilitates membrane association of the protein due to the hydrophobic nature of the lipid. We believe that FNTB-1 prenylates PRKL-1 at its C-terminal CAAX motif to promote membrane association and interaction in the PCP pathway. We will be describing the characterisation of
fntb-1 and genetic interactions with
prkl-1 as well as further findings from the genetic screen.