The small GTPase ARF-1.2 is a regulator of unicellular tube formation in Caenorhabditis elegans

J Physiol Sci. 2019 Jan;69(1):47-56. doi: 10.1007/s12576-018-0617-5. Epub 2018 Apr 27.


The membrane trafficking events that regulate unicellular tube formation and maintenance are not well understood. Here, using an RNAi screen, we identified the small GTPase ARF1 homolog ARF-1.2 as a regulator of excretory tube formation in Caenorhabditis elegans. RNAi-mediated knockdown and knockout of the arf-1.2 gene resulted in the formation of large intracellular vacuoles at the growth sites (varicosities) of the excretory canals. arf-1.2 mutant animals were sensitive to hyperosmotic conditions. arf-1.2 RNAi affected the localization of the anion transporter SULP-8, which is expressed in the basal plasma membrane of the excretory canals, but did not affect the expression of SULP-4, which is expressed in the apical membrane. The phenotype of arf-1.2 mutants was suppressed by mutation of the small Rho GTPase CDC-42, a regulator of apical/basal traffic balance. These results suggest that ARF-1.2 plays an essential role in basal membrane traffic to regulate the formation of the unicellular excretory tube.

Keywords: ARF-1.2; CDC-42; Caenorhabditis elegans; Small GTPase; Unicellular tube formation.

MeSH terms

  • Animals
  • Caenorhabditis elegans / growth & development*
  • Caenorhabditis elegans / metabolism
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Membrane / metabolism*
  • GTP Phosphohydrolases / genetics
  • GTP Phosphohydrolases / metabolism*
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism
  • RNA Interference


  • Caenorhabditis elegans Proteins
  • Cell Cycle Proteins
  • cdc-42 protein, C elegans
  • ARF-1.2 protein, C elegans
  • GTP Phosphohydrolases
  • GTP-Binding Proteins