FUNCTIONAL ANALYSIS OF LINKER-SCAN MUTANTS SPANNING THE −376, −308, −244, AND −238 POLYMORPHIC SITES OF THE TNF-α PROMOTER

Abstract

Tumor necrosis factor alpha (TNF-α) promoter polymorphisms have been linked to a large number of diseases but studies examining the possible direct functional effects of these polymorphisms have been contradictory. Previous studies compared TNF-α promoter constructs containing single nucleotide changes. We have now made a series of mutant constructs in which regions of the TNF-α promoter containing suspected functional single nucleotide polymorphisms, including −376, −308, −244 and −238, were replaced by a 10bp linker scan sequence. These constructs were transiently transfected into the T cell line Jurkat, the B cell line Raji, and the monocytic cell line U937, and tested for basal and induced transcriptional activity. Mutant constructs covering both the −308 and −376 polymorphisms showed no significant differences in either basal or induced transcriptional activity. Constructs covering the −244/−238 region showed a small increase in basal activity in the U937 cell line. These results indicate (i) that the −308 and −376 regions are of no functional relevance for TNF-α promoter transcription, and (ii) that the −244/−238 region does not influence transcription in some cell lines but may have some role in transcription in others.