Clathrin interaction and subcellular localization of Ce-DAB-1, an adaptor for protein secretion in Caenorhabditis elegans.
Growth factors must be secreted appropriately to co-ordinate cell proliferation, specification and movement during development and to control cell numbers and migrations in adult animals. Previous results showed that the secretion of the Caenorhabditis elegans fibroblast growth factor homologue, EGL-17, from vulval precursor cells in vivo involves the cytoplasmic adaptor protein Ce-DAB-1 and two lipoprotein receptors that bind Ce-DAB-1 and EGL-17. Here, we confirm the Ce-DAB-1 requirement for EGL-17 secretion using mutant animals. In vitro, Ce-DAB-1 binds to clathrin and APT-4, the C. elegans homologue of the alpha-adaptin subunit of adaptor protein 2 (AP2), and weakly to the gamma-appendage domains of APT-1 (AP1gamma-adaptin) and APT-9 (GGA protein). In tissue-culture cells, Ce-DAB-1 localizes to various compartments, including AP2-containing vesicles near the cell surface and perinuclear vesicles that contain AP1. The latter also contain Rab8, but not Rab5 or Rab11, as well as proteins en route from the trans Golgi network (TGN) to the surface. In vivo, EGL-17 secretion was inhibited by depletion of apt-1, apt-9 or ce-rab-8 and partially inhibited by RNAi of ce-rab-5, consistent with an important role for these proteins in the secretion of EGL-17 in vivo. These results suggest that Ce-DAB-1 might co-ordinate the assembly of endocytic or secretory vesicles in vivo and may mediate EGL-17 secretion directly, by recruiting clathrin to lipoprotein receptors at the TGN, or indirectly, by affecting lipoprotein receptor endocytosis and recycling.
Kamikura
Darren M
DM
Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
Cooper
Jonathan A
JA
D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics* / Q000254:growth & development*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002966:Clathrin / Q000378:metabolism*; D004705:Endocytosis; D005260:Female; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009154:Mutation; D011485:Protein Binding; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection; D019076:Transgenes
D033942:Adaptor Proteins, Vesicular Transport; D029742:Caenorhabditis elegans Proteins; D002966:Clathrin; C510381:DAB-1 protein, C elegans; C105157:Egl-17 protein, C elegans; D036341:Intercellular Signaling Peptides and Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D005982:Glutathione Transferase