Stabilin-1 localizes to endosomes and the trans-Golgi network in human macrophages and interacts with GGA adaptors.
Stabilin-1 and stabilin-2 constitute a novel family of fasciclin domain-containing hyaluronan receptor homologues recently described by us. Whereas stabilin-1 is expressed in sinusoidal endothelial cells and in macrophages in vivo, stabilin-2 is absent from the latter. In the present study, we analyzed the subcellular distribution of stabilin-1 in primary human ... macrophages. Using flow cytometry, expression of stabilin-1 was demonstrated on the surface of interleukin-4/dexamethasone-stimulated macrophages (MPhi2). By immunofluorescence and confocal microscopy, we established that stabilin-1 is preferentially localized in early endosome antigen-1-positive early/sorting endosomes and in recycling endosomes identified by transferrin endocytosis. Association of stabilin-1 was infrequently seen with p62 lck ligand-positive late endosomes and with CD63-positive lysosomes but not in lysosome-associated membrane protein-1-positive lysosomes. Stabilin-1 was also found in the trans-Golgi network (TGN) but not in Golgi stack structures. Glutathione S-transferase pull-down assay revealed that the cytoplasmic tail of stabilin-1 but not stabilin-2 binds to recently discovered Golgi-localized, gamma-ear-containing, adenosine 5'-diphosphate-ribosylation factor-binding (GGA) adaptors GGA1, GGA2, and GGA3 long, mediating traffic between Golgi and endosomal/lysosomal compartments. Stabilin-1 did not bind to GGA3 short, which lacks a part of the Vps27p/Hrs/STAM domain. Deletion of DDSLL and LL amino acid motifs resulted in decreased binding of stabilin-1 with GGAs. A small portion of stabilin-1 colocalized with GGA2 and GGA3 in the TGN in MPhi2. Treatment with brefeldin A resulted in accumulation of stabilin-1 in the TGN. Our results suggest that stabilin-1 is involved in the GGA-mediated sorting processes at the interface of the biosynthetic and endosomal pathways; similarly to other GGA-interacting proteins, stabilin-1 may thus function in endocytic and secretory processes of human macrophages.
Mesh Terms:
ADP-Ribosylation Factors, Adaptor Proteins, Vesicular Transport, Amino Acid Motifs, Antigens, CD, Antigens, CD63, Brefeldin A, Carrier Proteins, Cell Adhesion Molecules, Neuronal, Cell Compartmentation, Cells, Cultured, Dexamethasone, Endocytosis, Endosomes, Flow Cytometry, Humans, Interleukin-4, Lysosome-Associated Membrane Glycoproteins, Macrophages, Membrane Glycoproteins, Platelet Membrane Glycoproteins, Protein Binding, Protein Structure, Tertiary, Protein Transport, Receptors, Immunologic, Receptors, Lymphocyte Homing, Signal Transduction, Transferrin, trans-Golgi Network
ADP-Ribosylation Factors, Adaptor Proteins, Vesicular Transport, Amino Acid Motifs, Antigens, CD, Antigens, CD63, Brefeldin A, Carrier Proteins, Cell Adhesion Molecules, Neuronal, Cell Compartmentation, Cells, Cultured, Dexamethasone, Endocytosis, Endosomes, Flow Cytometry, Humans, Interleukin-4, Lysosome-Associated Membrane Glycoproteins, Macrophages, Membrane Glycoproteins, Platelet Membrane Glycoproteins, Protein Binding, Protein Structure, Tertiary, Protein Transport, Receptors, Immunologic, Receptors, Lymphocyte Homing, Signal Transduction, Transferrin, trans-Golgi Network
J. Leukoc. Biol.
Date: Dec. 01, 2004
PubMed ID: 15345724
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