A pathway for unicellular tube extension depending on the lymphatic vessel determinant Prox1 and on osmoregulation

Nat Cell Biol. 2013 Feb;15(2):157-68. doi: 10.1038/ncb2662. Epub 2013 Jan 20.


The mechanisms regulating the extension of small unicellular tubes remain poorly defined. Here we identify several steps in Caenorhabditis elegans excretory canal growth, and propose a model for lumen extension. Our results suggest that the basal and apical excretory membranes grow sequentially: the former extends first like an axon growth cone; the latter extends next as a result of an osmoregulatory activity triggering peri-apical vesicles (a membrane reservoir) to fuse with the lumen. An apical cytoskeletal web including intermediate filaments and actin crosslinking proteins ensures straight regular lumen growth. Expression of several genes encoding proteins mediating excretory lumen extension, such as the osmoregulatory STE20-like kinase GCK-3 and the intermediate filament IFB-1, is regulated by ceh-26 (here referred to as pros-1), which we found essential for excretory canal formation. Interestingly, PROS-1 is homologous to vertebrate Prox1, a transcription factor controlling lymphatic vessel growth. Our findings have potential evolutionary implications for the origin of fluid-collecting organs, and provide a reference for lymphangiogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Animals
  • Animals, Genetically Modified
  • Caenorhabditis elegans / embryology
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans / ultrastructure
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Cell Membrane / metabolism*
  • Cell Membrane / ultrastructure
  • Gene Expression Regulation, Developmental
  • Genotype
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Humans
  • Intermediate Filament Proteins / metabolism
  • Intermediate Filaments / metabolism
  • Lymphangiogenesis*
  • Lymphatic Vessels / embryology
  • Lymphatic Vessels / metabolism*
  • Morphogenesis
  • Osmotic Pressure
  • Phenotype
  • Protein-Serine-Threonine Kinases / metabolism
  • RNA Interference
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*
  • Water-Electrolyte Balance*


  • Caenorhabditis elegans Proteins
  • Homeodomain Proteins
  • IFB-1 protein, C elegans
  • Intermediate Filament Proteins
  • Tumor Suppressor Proteins
  • prospero-related homeobox 1 protein
  • Protein-Serine-Threonine Kinases
  • gck-3 protein, C elegans