2004 West Coast Worm Meeting abstract 34
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
| 1 | Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison |
| 2 | School of Pharmacy, UW-Madison |
In <i)C. elegans, sexual mating requires stereotypical sub-steps by the male: response (Resp), backing, turning, location of vulva (Lov), spicule insertion, and sperm transfer. The lov-2(sy511) mutant was identified in an EMS-behavioral screen. lov-2 males specifically exhibit defects in Resp and Lov substeps. Mutations in lov-1 and pkd-2, the C. elegans homologues of mammalian polycystic kidney genes PKD1 and PKD2, also result in Resp and Lov phenotypes. To test for genetic interactions between lov-2, lov-1 and pkd-2, we rigorously quantified the Resp and Lov defects of single, double and triple mutants. Our data reveals that the lov-2(sy511) mutation is epistatic to lov-1 and pkd-2. As another test for interactions, we analyzed the sub-cellular expression of an integrated PKD-2::GFP transgene. PKD-2 expression is restricted to tips of cilia but absent along dendrites in wild type males. In a lov-2(sy511) background, PKD-2 is grossly mislocalized along dendrites. However, cilia appear normal in lov-2(sy511) male neurons.
Recombination mapping and transformation rescue show that lov-2 encodes a kinesin belonging to the UNC-104/Kif1a subfamily. Consistent with its mutant phenotype, lov-2 co-expresses and co-localizes with lov-1 and pkd-2 in cilia of male specific ray (RnB), hook (HOB) and CEM neurons. lov-2 is additionally expressed in the 3 pairs of IL2 neurons, which, although they do not express lov-1 and pkd-2, have cilia that are exposed to the environment like those of the CEMs, RnBs and HOB.
UNC-104/Kif1a family members are composed of an N-Terminal Motor head domain (ATP and microtubule binding domains), followed by a coiled-coil, hinge region important for multimerization and motor regulation, and a C-terminal tail of variable length and composition. To understand how these modules contribute to LOV-2 localization and function, we analyzed the in vivo expression and function of a series of LOV-2::GFP fragments in wild type and lov-2(sy511): 1. MOTOR 2. HINGE 3. MOTOR+HINGE 4. TAIL, and 5. HINGE+TAIL. We present evidence that the LOV-2 TAIL contains a ciliary-targeting motif.
Together, our results suggest that the kinesin LOV-2 provides a crucial microtubule-dependent activity in dendrites and/or cilia of male specific neurons necessary for LOV-1 and PKD-2 ciliary localization and male mating behavior. We conclude that lov-2 is required for the function of a subset of cilia, but not cilia formation.