Interaction of members of the heat shock protein-70 family with the macrophage mannose receptor.
The macrophage MR has been the subject of investigation for over 20 years, and several important physiological functions have been described. However, the molecular mechanisms that regulate MR signaling and trafficking during these processes still remain elusive. The focus of the current paper was to identify potential cellular MR-interacting proteins. An initial screen of binding proteins in MR-expressing cells was performed using coimmunoprecipitation, followed by identification of matching peptide sequences using proteomics and MS. The major class of binding proteins identified belonged to the heat shock family of proteins. The specific interaction of the MR with HSP70 family members was validated by Western blot analysis, ligand binding assays, and intracellular colocalization using confocal microscopy. Additional studies indicated that inhibition of the HSP BiP by treatment of cells with EGCG reduced BiP interaction with and surface expression of the MR. Studies of possible motifs within the cytoplasmic tail of the receptor suggested that a juxtamembrane dibasic sequence may contribute to the interaction with BiP. These findings suggest that the molecular association of the MR with HSP70 family members via the receptor cytoplasmic tail may contribute to MR trafficking in macrophages.
Department of Veterans Affairs Medical Center, Vanderbilt University, Nashville, Tennessee, USA.
Seungchan
S
Yang
David J
DJ
Vigerust
Virginia L
VL
Shepherd
D000595:Amino Acid Sequence; D001665:Binding Sites; D015153:Blotting, Western; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D015870:Gene Expression; D057809:HEK293 Cells; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010957:Plasmids; D011485:Protein Binding / Q000187:drug effects; D054730:Protein Interaction Domains and Motifs; D021381:Protein Transport / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D018840:HSP70 Heat-Shock Proteins; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D002392:Catechin; C045651:epigallocatechin gallate