Subcellular localization of the melanoma-associated protein Melan-AMART-1 influences the processing of its HLA-A2-restricted epitope.
The peptide derived from the melanoma-associated protein Melan-A (Melan-A(26-35)/HLA-A2) is an attractive candidate for tumor immunotherapy but little is known about the intracellular processing of this antigen. Here we show that Melan-A is a single-pass membrane protein with an NH(2) terminus exposed to the lumen of the exocytic compartment. In transfected melanoma cells, Melan-A accumulates in the Golgi region. Inversion of the membrane topology leads to the retention of Melan-A in the endoplasmic reticulum. Most strikingly, melanoma cells expressing this form of Melan-A are more effectively recognized by specific CTL than those expressing either Melan-A in its native membrane orientation or Melan-A artificially localized in the cytosol. Our data are compatible with the notion that proteins retained in the endoplasmic reticulum are more efficiently degraded and produce more antigenic peptides.
Rimoldi
D
D
Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, CH-1066 Epalinges, Switzerland. Donata.Rimoldi@isrec.unil.ch
Muehlethaler
K
K
Salvi
S
S
Valmori
D
D
Romero
P
P
Cerottini
J C
JC
Levy
F
F
D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000939:Epitopes; D005089:Exocytosis; D006026:Glycoside Hydrolases / Q000494:pharmacology; D006056:Golgi Apparatus / Q000378:metabolism; D015789:HLA-A2 Antigen / Q000096:biosynthesis / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D058965:MART-1 Antigen; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000494:pharmacology; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
D000951:Antigens, Neoplasm; D000939:Epitopes; D015789:HLA-A2 Antigen; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009097:Multienzyme Complexes; D009363:Neoplasm Proteins; D010455:Peptides; D006026:Glycoside Hydrolases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex