Effects of stimulus and cell type on the expression of the - 308 tumour necrosis factor promoter polymorphism

The authors have previously demonstrated that the tumour necrosis factor (T NF) - 308 G/A polymorphism affects the binding of transcription factors. Tn transient transfection assays in PMA stimulated U937 monocytes and Jurkat T cells, the A-containing TNF2 promoter has a 2-3-fold greater transcriptio nal activity than the TNF1 promoter in the presence of the TNF 3'UTR, In th is study it was found that a difference in TNF1 and TNF2 promoter activitie s was only observed in U937 and Jurkat cells, and not in Raji (B cell line) , HeLa (epithelial carcinoma cell line), HepG2 (hepatoma cell line) or THP- 1 (monocyte), suggesting cell-type specific transcription factors or modifi cations may be involved in the formation of the - 308 protein/ DNA complex. Physiological stimulators, TNF and interferon gamma (IFN-gamma) did not ca use differential promoter activity between TNF1 and TNF2, but T,PS did with only the TNF2 promoter/3'UTR construct being significantly responsive to l ipopolysaccharide (LPS) in U937 cells. In U937 cells, the - 308 polymorphis m affected transcription following differentiation by phorbol myristate ace tate (PMA), retinoic acid, PMA plus LPS and PMA plus retinoic acid with an increase in nuclear factor binding to both TNF1 and TNF2 in the - 323 to - 285 region being observed. The greatest difference between TNF2 and TNF1 pr omoter activities (5-fold) was observed following PMA plus retinoic acid tr eatment of transfected U937 cells for 48h, During this time, U937 different iated into cells with a macrophage-like morphology. An understanding of the cell type and stimuli specific requirements for differential expression of the - 308 polymorphism may help elucidate the role the TNF - 308 polymorph ism plays in diseases where elevated TNF levels are thought to be important . (C) 2000 Academic Press.