• Authors: Nekhoroshkova, E., Albert, S., Becker, M., Rapp, U. R.
  • Year: 2009
  • Journal: PLoS One 4 e4647
  • Applications: in vitro / DNA / jetPEI
  • Cell types:
    1. Name: COS-7
      Description: African green monkey kidney cells
      Known as: COS, COS7
    2. Name: HeLa
      Description: Human cervix epitheloid carcinoma cells
    3. Name: NIH/3T3
      Description: Murine embryonic fibroblasts
      Known as: NIH/3T3, 3T3


BACKGROUND: RAF kinases direct ERK MAPK signaling to distinct subcellular compartments in response to growth factor stimulation. METHODOLOGY/PRINCIPAL FINDINGS: Of the three mammalian isoforms A-RAF is special in that one of its two lipid binding domains mediates a unique pattern of membrane localization. Specific membrane binding is retained by an N-terminal fragment (AR149) that corresponds to a naturally occurring splice variant termed DA-RAF2. AR149 colocalizes with ARF6 on tubular endosomes and has a dominant negative effect on endocytic trafficking. Moreover actin polymerization of yeast and mammalian cells is abolished. AR149/DA-RAF2 does not affect the internalization step of endocytosis, but trafficking to the recycling compartment. CONCLUSIONS/SIGNIFICANCE: A-RAF induced ERK activation is required for this step by activating ARF6, as A-RAF depletion or inhibition of the A-RAF controlled MEK-ERK cascade blocks recycling. These data led to a new model for A-RAF function in endocytic trafficking.