Organization and functional analysis of the mouse transporter associated with antigen processing 2 promoter.
In accordance with the key role of MHC class I molecules in the adaptive immune response against viruses, they are expressed by most cells, and their expression can be enhanced by cytokines. The assembly and cell surface expression of class I complexes depend on a continuous peptide supply. The peptides are generated mainly by the proteasome and are transported to the endoplasmic reticulum by a peptide transport pump consisting of two subunits, TAP1 and TAP2. The proteasome low molecular weight polypeptide (2 and 7), as well as TAP (1 and 2) genes, are coordinately regulated and are induced by IFNs. Despite this coordinate regulation, examination of tumors shows that these genes can be discordantly down-regulated. In pursuing a molecular explanation for these observations, we have characterized the mouse TAP2 promoter region and 5'-flanking sequence. We show that the 5' untranslated regions of TAP2 genes have a characteristic genomic organization that is conserved in both the mouse and the human. The mouse TAP2 promoter belongs to a class of promoters that lack TATA boxes but contain a MED1 (multiple start site element downstream) sequence. Accordingly, transcription is initiated from multiple sites within a 100-nucleotide window. An IFN regulatory factor 1 (IRF1)/IRF2 binding site is located in this region and is involved in both basal and IRF1-induced TAP2 promoter activity. The implication of the extensive differences found among the promoters of class I heavy chain, low molecular weight polypeptide, and TAP genes, all encoding proteins involved in Ag presentation, is discussed.
Department of Cell Research and Immunology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel.
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Arons
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Kunin
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Schechter
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Ehrlich
D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D006224:Cricetinae; D003546:Cysteine Endopeptidases; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005805:Genes, MHC Class I; D006071:Gorilla gorilla; D006801:Humans; D050856:Interferon Regulatory Factor-1; D050836:Interferon Regulatory Factor-2; D051379:Mice; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000276:immunology*; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D051381:Rats; D012097:Repressor Proteins; D020218:Response Elements / Q000276:immunology; D017422:Sequence Analysis, DNA; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000276:immunology
D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; C494229:IRF2 protein, human; D050856:Interferon Regulatory Factor-1; D050836:Interferon Regulatory Factor-2; C494258:Irf1 protein, mouse; C494259:Irf1 protein, rat; C494230:Irf2 protein, mouse; D009097:Multienzyme Complexes; D010750:Phosphoproteins; D011506:Proteins; D012097:Repressor Proteins; C489516:Tap2 protein, mouse; C489514:Tap2 protein, rat; D014157:Transcription Factors; C071692:TAP2 protein, human; D003546:Cysteine Endopeptidases; C077436:LMP7 protein; D046988:Proteasome Endopeptidase Complex