C. elegans ten-1 is synthetic lethal with mutations in cytoskeleton regulators, and enhances many axon guidance defective mutants

BACKGROUND: Teneurins are transmembrane proteins that assist morphogenetic processes in many organisms. ten-1 is the C. elegans teneurin homolog with two transcripts, ten-1a and ten-1b, that respectively encode a long (TEN-1L) and short (TEN-1S) form of the protein. We previously isolated a C. elegans mutant where one pharyngeal neuron was frequently misplaced, and now show that it corresponds to a novel allele of ten-1. RESULTS: The novel ten-1(et5) allele is a hypomorph since its post-embryonic phenotype is weaker than the null alleles ten-1(ok641) and ten-1(tm651). ten-1 mutants have defects in all pharyngeal neurons that we examined, and in vivo reporters show that only the long form of the ten-1 gene is expressed in the pharynx, specifically in six marginal cells and the M2 neurons. Defects in the pharyngeal M2 neurons were enhanced when the ten-1(ok641) mutation was combined with mutations in the following genes: mig-14, unc-5, unc-51, unc-52 and unc-129. None of the body neurons examined show any defects in the ten-1(ok641) mutant, but genetic interaction studies reveal that ten-1(ok641) is synthetic lethal with sax-3, unc-34 and unc-73, and examination of the hypodermal cells in embryos of the ten-1(ok641) mutant point to a role of ten-1 during hypodermal cell morphogenesis. CONCLUSIONS: Our results are consistent with ten-1 normally providing a function complementary to the cytoskeletal remodeling processes that occur in migrating cells or cells undergoing morphogenesis. It is possible that ten-1 influences the composition/distribution of extracellular matrix.