Dynamics within tetraspanin pairs affect MHC class II expression.
Late endosomal multivesicular bodies (MVBs) are complicated organelles with various subdomains located at the limiting membrane and the internal vesicles (ILVs). ILVs accumulate tetraspanins such as CD63 and CD82 that might form protein assemblies, including major histocompatibility complex class II (MHC-II) and its chaperone human leukocyte antigen (HLA)-DM. Here, we studied the effect of four late endosomal tetraspanin proteins on MHC-II expression. Silencing CD9, CD63 and CD81 enhanced MHC-II expression whereas silencing CD82 did not. No effect on peptide loading was observed. Using confocal FRET technology, we measured the dynamics of CD63 and CD82 interaction with MHC-II and its chaperone HLA-DM. CD63-CD82 interactions remained unaltered in the two MVB subdomains whereas the interactions between CD63 or CD82 homologous pairs changed. CD63 stably associated with MHC-II, and CD82 with HLA-DM, on both MVB subdomains whereas the CD82-MHC-II and CD63-HLA-DM interactions changed. These data visualize for the first time the protein dynamics of tetraspanin assemblies in MVB subdomains. CD63, unlike CD82, stably interacts with MHC-II at both MVB subdomains and controls MHC-II expression.
Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam,  The Netherlands.
Tineke van den
Tv
Hoorn
Petra
P
Paul
Lennert
L
Janssen
Hans
H
Janssen
Jacques
J
Neefjes
D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002738:Chloroquine / Q000494:pharmacology; D004058:Diffusion; D031541:Fluorescence Resonance Energy Transfer; D057809:HEK293 Cells; D006681:HLA-D Antigens / Q000378:metabolism*; D006684:HLA-DR Antigens / Q000378:metabolism; D006801:Humans; D051861:Kangai-1 Protein / Q000378:metabolism*; D057146:Multivesicular Bodies / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D060149:Tetraspanin 30 / Q000378:metabolism*; D059470:Tetraspanins / Q000378:metabolism
D006681:HLA-D Antigens; C084245:HLA-DM antigens; D006684:HLA-DR Antigens; D051861:Kangai-1 Protein; D060149:Tetraspanin 30; D059470:Tetraspanins; D002738:Chloroquine