Fig. 1

NF-κB deficient Tax mutants are functional but poorly expressed on protein level in Jurkat T-cells. a Schematic presentation of the amino acid sequence of Tax protein. Point mutations resulting in the Tax mutant proteins M7 (C29A, P30S), M22 (T130A, L130S), M47 (L319R, L320S) and S113A (S113A) are indicated. b Jurkat T-cells were transiently transfected with an empty vector (mock), the Tax-1 expression plasmids Tax (wildtype), M47 (CREB-deficient), M22 (NF-κB-deficient) or M7 (CREB- and NF-κB-deficient), all in the pEF-1α backbone, with the same set of Tax-1 expression plasmids in the pcDNA backbone (50 µg each), or with the pEF-1α based Tax expression plasmids Tax (wildtype) and S113A (30 µg each). Western Blot analysis shows Tax protein and α-Tubulin as a loading control. c Jurkat T-cells were co-transfected with an empty vector (mock) or the Tax expression constructs Tax, M47, M22, M7 or S113A, all in the pEF-1α backbone (30 µg each), together with the luciferase reporter vector for the U3R promoter from the HTLV-1 5′ LTR region (U3R-Luc), or a luciferase reporter vector carrying five NF-κB responsive elements (NF-κB-Luc; 20 µg each). Values were normalized on protein content and on luciferase background activity. One representative experiment ± SD is shown. d Jurkat T-cells were transfected with an empty vector (mock) or the Tax expression constructs Tax, M47, M22, M7 or S113A, all in the pEF-1α backbone (30 µg each), replenished with 70 µg of an empty vector (pcDNA). Tax transcript levels were measured by quantitative PCR (qPCR), and mean relative copy numbers (rcn), normalized on β-actin (ACTB), of three (M47, M22 and M7) or four (S113A) independent experiments ± SD or SE, respectively, were compared using student’s t-test n.s. not significant