A common functional polymorphism (C-->A substitution at position -863) in the promoter region of the tumour necrosis factor-alpha (TNF-alpha) gene associated with reduced circulating levels of TNF-alpha.
Tumour necrosis factor-alpha (TNF-alpha) plays a key role in orchestrating the complex events involved in inflammation and immunity. Accordingly, TNF-alpha has been implicated in a wide range of autoimmune and infectious diseases, but also in conditions such as obesity and insulin resistance. The regulation of TNF-alpha expression in man is indicated to be partly genetically determined. We therefore screened a 1263 bp section of the proximal promoter of the TNF-alpha gene for common genetic variants affecting the transcriptional activity of the gene. Here we report the characterization of a common functional polymorphism in the promoter region of the TNF-alpha gene, a C-->A substitution at position -863. Electromobility shift assays provided evidence for a distinct difference in the binding of monocytic and hepatic nuclear factors to the -863C and -863A alleles. The rare -863A allele was associated with 31% lower transcriptional activity ( P < 0.001) in chloramphenicol acetyltransferase (CAT) reporter gene studies in human hepatoblastoma (HepG2) cells, indicating that the-863C/A polymorphism influences the basal rate of transcription of the TNF-alpha gene in vitro. Allele frequencies were 0.83/0.17 amongst 254 apparently healthy men of Swedish origin, aged 35-50 years. In 156 men, the -863C/A polymorphism was associated with the serum TNF-alpha concentration, carriers of the rare A allele having a significantly lower TNF-alpha level ( P < 0.05). It is concluded that the common-863C/A polymorphism in the promoter region of the TNF-alpha gene is functional in vitro in monocytic and hepatic cells and influences the serum TNF-alpha concentration in vivo in healthy middle-aged men.
Atherosclerosis Research Unit, King Gustaf V Research Institute, Karolinska Institutet, Karolinska Hospital, S-171 76 Stockholm, Sweden. tiinasko@instmed.ks.se
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Skoog
F M
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van't Hooft
B
B
Kallin
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S
Jovinge
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Boquist
J
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Nilsson
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Eriksson
A
A
Hamsten
D000328:Adult; D000483:Alleles; D001665:Binding Sites / Q000235:genetics; D005786:Gene Expression Regulation; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D015846:Monokines / Q000097:blood* / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D017354:Point Mutation; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D014158:Transcription, Genetic / Q000235:genetics; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D015846:Monokines; D009687:Nuclear Proteins; D014409:Tumor Necrosis Factor-alpha