Fig. 4

Promoter activities of HML-10 LTRs. a LTRs of the HML-10(DAP3), HML-10(C4) and HML-10(PKIB) proviruses were cloned in both orientations into the promoter-free pGL3-Enhancer vector and transfected into HepG2 or HEK293T cells. Firefly luciferase (fLuc) activities were determined 24 h after transfection b Promoter activities expressed as fLuc activity normalized to renilla luciferase (rLuc) activity of the co-transfected pGL4.74 vector in the indicated cell lines. The pGL3-Control vector bearing the SV40 promoter (grey bars) served as positive and empty pGL3-Enhancer (white bars) as negative control. Promoter activities were normalized to pGL3-Control set to 100%. The bars show mean ± SEM of three independent experiments in duplicates. *P-value ≤ 0.05, Student’s t-Test compared to pGL3-Enhancer. c For HepG2 cells the effect of IFNγ stimulation on two selected LTRs as well as the SV40 and HSV-TK promoters is shown. LTR and SV40 activity is expressed as fLuc normalized to rLuc signals, HSV-TK activity is expressed as rLuc activity only. The bars show mean ± SEM of at least three independent experiments and were normalized to unstimulated (-) cells set to 100%. n.d., not determined. d Identification of a conserved IFNγ activated site (GAS) of the consensus sequence 5′-TTNCNNNAA-3′ [45]. e Locations of primers used to detect transcripts originating from the 5′LTR of HML-10(DAP3). The predicted TSS was identified as described in the text and Additional file 1: Figure S1. f Detection of DAP3 mRNA and HML-10(DAP3) transcripts in HepG2 and HeLa cells by qRT-PCR. cDNA samples prepared without reverse transcriptase (RT) for the indicated primer pairs, but with RT for GAPDH, served as controls. Values are normalized to GAPDH mRNA levels. Bars show mean ± SD of two measurements. In most cases, the SD is too small to be visible