MRP8 and MRP14, S-100-like proteins associated with myeloid differentiation, are translocated to plasma membrane and intermediate filaments in a calcium-dependent manner.
MRP8 and MRP14 are two Ca(2+)-binding proteins of the S-100 family expressed by myelomonocytic cells. Both proteins assemble to noncovalently associated complexes in a Ca(2+)-dependent manner. Members of the S-100 family are known to play a role in cytoskeletal-membrane interactions; therefore, we investigated the subcellular distribution of MRP8/MRP14 and their complexes in human monocytes. Using differential centrifugation and subsequent Western blot or enzyme-linked immunosorbent assay analysis, we found that MRP8/MRP14 were almost completely translocated from the cytoplasma to membrane and cytoskeletal structures in a Ca(2+)-dependent manner. Using a cross-linking technique, complexed forms of MRP8/MRP14 were found to be associated with the plasma membrane. Analysis of MRP-transfected L132 cells showed that the MRP8 as well as the MRP14 component of the MRP8/MRP14 complex may independently bind to membrane and cytoskeletal structures. Furthermore, immunogold electron microscopy showed a colocalization of MRP8/MRP14 and the intermediate filament type III protein vimentin in A23187-treated monocytes. Our data indicate that, in analogy to other S-100-like proteins, MRP8 and MRP14 play a role in Ca(2+)-dependent cytoskeletal-membrane interactions. Restriction of MRP8/MRP14 expression to distinct stages of myelomonocytic differentiation suggests that these proteins are involved in highly specific pathways of intracellular signaling in phagocytes.
Roth
J
J
Institute of Experimental Dermatology, University of Münster, Germany.
Burwinkel
F
F
van den Bos
C
C
Goebeler
M
M
Vollmer
E
E
Sorg
C
C
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology*; D002135:Calcium-Binding Proteins / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D040501:Calgranulin A; D040502:Calgranulin B; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007382:Intermediate Filaments / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D009000:Monocytes / Q000166:cytology* / Q000378:metabolism*; D014162:Transfection; D014746:Vimentin / Q000032:analysis
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D002135:Calcium-Binding Proteins; D040501:Calgranulin A; D040502:Calgranulin B; D014746:Vimentin; D002118:Calcium