PKD-2 and LOV-1 are a putative mechanosensory transient receptor potential channel-receptor polycystin (TRPP) complex that is required for male mating behaviors. PKD-2 and LOV-1 localize to cilia found at the end of dendrites of male-specific sensory neurons, which include the CEMs in the head and the RnB and HOB neurons in the tail.
pkd-2 and
lov-1 mutants are defective in responding to hermaphrodites and exhibit location of vulva (Lov) defects. Mutations in PKD1 and PKD2, the human homologs of
lov-1 and
pkd-2, cause ADPKD. As in C. elegans, the mammalian TRPPs localize to cilia on renal epithelial cells. In C. elegans localization of PKD-2 to cilia requires the kinesin-3 KLP-6. We previously screened for mutants exhibiting mislocalization of PKD-2::GFP (Bae et al 2008). In the ciliary localization (Cil) defective mutant
my16, we observe an abnormal accumulation of PKD-2::GFP in CEM cilia as well as along the distal dendrites of the RnB and HOB neurons.
my16 males also exhibit response defects. We are interested in determining the effects of
my16 on male sensory behaviors, including sex drive, response, and vulva location. We are also examining genetic interactions between
my16,
pkd-2, and other components in the PKD pathway. In the wild-type male head, KLP-6::GFP is expressed in and localizes throughout the CEM and IL2 neurons. In CEM neurons,
my16 males mislocalize the KLP-6 kinesin motor protein in both globular structures and small puncta located laterally along dendritic endings. In core IL2 neurons, KLP-6::GFP looks similar between wild-type and
my16 animals. This suggests that the
my16 mutation specifically affects the CEMs with respect to KLP-6::GFP localization. Similar to the
my16 single mutant, the
my16;
pkd-2 double mutant exhibits mislocalized KLP-6::GFP, indicating that this phenotype is PKD-2 cargo independent. We are interested in determining whether
my16 acts in the core ciliated nervous system.
my16 mutants are nonDyf (dye filling defective), suggesting that ciliogenesis in amphids and phasmids is intact. To confirm this, we examined the localization of the intraflagellar transport (IFT) reporter OSM-5::GFP. OSM-5::GFP subcellular distribution appears unaltered in
my16 males.
my16 hermaphrodites are defective in chemotaxis to diacetyl and benzaldehyde, suggesting functions in the core nervous system. We will clone the gene mutated in
my16 animals using three factor and SNP mapping combined with whole genome sequencing. The molecular identification will provide important insight into how PKD-2 localizes to cilia, with the ultimate goal of gaining knowledge into human ciliopathies.