The -308 tumor necrosis factor-alpha promoter polymorphism effects transcription.
Since the tumor necrosis factor alpha (TNF-alpha) gene was found to be located in the central major histocompatibility complex (MHC) there has been much speculation concerning a genetic association between particular TNF alleles and disease susceptibility. A relationship between the MHC haplotype A1, B8, DR3, TNF-alpha expression levels and susceptibility to autoimmune disease has been suggested by several groups. The identification of the -308 polymorphism and its association with the HLA A1, B8, DR3 haplotype have led to speculation that the polymorphism may play a role in the altered expression of TNF-alpha. We have demonstrated that the region (-323 to -285) encompassing -308 in the TNF2 allele binds nuclear factors differently to the same region in the promoter of the more common TNF1 allele. The G/A -308 polymorphism affected the affinity of factor binding and resulted in a factor binding to TNF2 but not TNF1. The observed differential binding was shown to be functional, with the 38bp region from TNF2 causing a two-fold greater activity of a heterologous promoter over that due to the same region in TNF1. To further substantiate the functional consequences of the TNF-alpha -308 polymorphism, we analysed both allelic forms of the TNF-alpha promoter region (-993 to +110) in a transient transfection assay, using luciferase as a reporter gene. The results showed that when present with the 3'UTR the -308A allelic form gave a two-fold greater level of transcription than the 308G form in PMA-stimulated Jurkat and U937 cells. This suggests that the -308 G/A polymorphism may play a role in the altered TNF-alpha gene expression observed in individuals with the HLA A1, B8, DR3 haplotype.
Kroeger
K M
KM
Department of Biochemistry, The University of Western Australia, Perth, Nedlands.
Carville
K S
KS
Abraham
L J
LJ
D001483:Base Sequence; D006528:Carcinoma, Hepatocellular; D002461:Cell Line, Transformed; D004268:DNA-Binding Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D009687:Nuclear Proteins / Q000378:metabolism; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic / Q000276:immunology*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000276:immunology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha