Downregulation of peptide transporter genes in cell lines transformed with the highly oncogenic adenovirus 12.
The expression of class I major histocompatibility complex antigens on the surface of cells transformed by adenovirus 12 (Ad12) is generally very low, and correlates with the high oncogenicity of this virus. In primary embryonal fibroblasts from transgenic mice that express both endogenous H-2 genes and a miniature swine class I gene (PD1), Ad12-mediated transformation results in suppression of cell surface expression of all class I antigens. Although class I mRNA levels of PD1 and H-2Db are similar to those in nonvirally transformed cells, recognition of newly synthesized class I molecules by a panel of monoclonal antibodies is impaired, presumably as a result of inefficient assembly and transport of the class I molecules. Class I expression can be partially induced by culturing cells at 26 degrees C, or by coculture of cells with class I binding peptides at 37 degrees C. Analysis of steady state mRNA levels of the TAP1 and TAP2 transporter genes for Ad12-transformed cell lines revealed that they both are significantly reduced, TAP2 by about 100-fold and TAP1 by 5-10-fold. Reconstitution of PD1 and H-2Db, but not H-2Kb, expression is achieved in an Ad12-transformed cell line by stable transfection with a TAP2, but not a TAP1, expression construct. From these data it may be concluded that suppressed expression of peptide transporter genes, especially TAP2, in Ad12-transformed cells inhibits cell surface expression of class I molecules. The failure to fully reconstitute H-2Db and H-2Kb expression indicates that additional factors are involved in controlling class I gene expression in Ad12-transformed cells. Nevertheless, these results suggest that suppression of peptide transporter genes might be an important mechanism whereby virus-transformed cells escape immune recognition in vivo.
Rotem-Yehudar
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R
Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel.
Winograd
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S
Sela
S
S
Coligan
J E
JE
Ehrlich
R
R
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D000256:Adenoviridae / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D000954:Antigens, Surface / Q000276:immunology / Q000378:metabolism; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002472:Cell Transformation, Viral; D015536:Down-Regulation; D000939:Epitopes / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals / Q000235:genetics / Q000378:metabolism*; D013552:Swine; D013556:Swine, Miniature; D013696:Temperature; D014162:Transfection
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D000954:Antigens, Surface; D002352:Carrier Proteins; D000939:Epitopes; D015395:Histocompatibility Antigens Class I; D021382:Protein Sorting Signals; C073119:TAP1 protein, human; C486171:Tap1 protein, mouse; C489516:Tap2 protein, mouse; C071692:TAP2 protein, human