Figure 7.

Overexpression of JAK1 restores IFN-γ stimulated gene expression (A). PTA cells (5 × 10⁵) were electroporated with pIRE-luciferase (10 μg) and 5 μg of indicated expression vector. They were then treated with murine IFN-γ (150 units/ml) for 18 h prior to luciferase assay with equal amount of cell extracts (70 μg). Bars = mean luciferase activity ± SEM of triplicate samples. pRK5, expression vector alone; JAK1, pRK5 with wild-type JAK1 cDNA; JAK1-KE, pRK5 with a mutant JAK1 cDNA that lacks kinase activity. LT inhibits JAK1 function (B) U4A cells were transfected with pIRE-luciferase (8 μg) and indicated expression vector (4 μg). Total amount of DNA (12 μg) transfected was kept constant by adding pRK5 where necessary. Luciferase assay was performed as in panel A except that cells were treated with human IFN-γ (150 U/ml). “+” and “−” indicate presence or absence of the plasmid in transfection mixture, respectively. In the case of IFN-γ they indicate treatment or nontreatment, respectively.