Rab23, a negative regulator of hedgehog signaling, localizes to the plasma membrane and the endocytic pathway

Traffic. 2003 Dec;4(12):869-84. doi: 10.1046/j.1600-0854.2003.00141.x.


The regulation of hedgehog signaling by vesicular trafficking was exemplified by the finding that Rab23, a Rab-GTPase vesicular transport protein, is mutated in open brain mice. In this study, the localization of Rab23 was analyzed by light and immunoelectron microscopy after expression of wild-type (Rab23-GFP), constitutively active Rab23 (Rab23Q68L-GFP), and inactive Rab23 (Rab23S23N-GFP) in a range of mammalian cell types. Rab23-GFP and Rab23Q68L-GFP were predominantly localized to the plasma membrane but were also associated with intracellular vesicular structures, whereas Rab23S23N-GFP was predominantly cytosolic. Vesicular Rab23-GFP colocalized with Rab5Q79L and internalized transferrin-biotin, but not with a marker of the late endosome or the Golgi complex. To investigate Rab23 with respect to members of the hedgehog signaling pathway, Rab23-GFP was coexpressed with either patched or smoothened. Patched colocalized with intracellular Rab23-GFP but smoothened did not. Analysis of patched distribution by light and immunoelectron microscopy revealed it is primarily localized to endosomal elements, including transferrin receptor-positive early endosomes and putative endosome carrier vesicles and, to a lesser extent, with LBPA-positive late endosomes, but was excluded from the plasma membrane. Neither patched or smoothened distribution was altered in the presence of wild-type nor mutant Rab23-GFP, suggesting that despite the endosomal colocalization of Rab23 and patched, it is likely that Rab23 acts more distally in regulating hedgehog signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biotin / chemistry
  • Biotin / metabolism
  • Blotting, Western
  • Cell Membrane / metabolism*
  • Cricetinae
  • Cytosol / metabolism
  • DNA / chemistry
  • DNA, Complementary / metabolism
  • Endocytosis
  • Endosomes / metabolism
  • Golgi Apparatus / metabolism
  • Green Fluorescent Proteins
  • Humans
  • Luminescent Proteins / metabolism
  • Mesocricetus
  • Mice
  • Microscopy, Fluorescence
  • Microscopy, Immunoelectron
  • Mutation
  • RNA, Messenger / metabolism
  • Recombinant Fusion Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction
  • Time Factors
  • Transfection
  • Transferrin / chemistry
  • Transferrin / metabolism
  • rab GTP-Binding Proteins / metabolism
  • rab GTP-Binding Proteins / physiology*


  • DNA, Complementary
  • Luminescent Proteins
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • Transferrin
  • Green Fluorescent Proteins
  • Biotin
  • DNA
  • RAB23 protein, human
  • Rab23 protein, mouse
  • rab GTP-Binding Proteins