Fig. 3.

The proximal PU.1 binding site in the Hotairm1 promoter induces luciferase gene expression in Gr1⁺CD11b⁺ cells. a A diagram of wild-type and mutant reporter constructs containing the proximal promoter region of Hotairm1 cloned upstream of the luciferase gene. b Gr1⁺CD11b⁺ cells were isolated from the bone marrow of post-acute septic mice. The cells were transfected with the indicated luciferase constructs. After 48 h, the cells were harvested for the measurement of firefly and Renilla luciferase activities. A luciferase vector with the GAPDH promoter served as a positive control for maximum firefly luciferase gene activity. Background reading from transfection with a negative control vector was subtracted, and firefly luciferase values were normalized to Renilla luciferase activity. Data are means ± SD for 6 mice per group, from 3 experiments, and are presented as firefly/Renilla ratio. *p < 0.05 versus PU.1 mutant 1. MDSCs, myeloid-derived suppressor cells.