FIGURE 5.

Modulation of reporter gene activation in BJAB cells expressing FCRL4 and the HCK p59 or FGR src-family kinases. (A) BJAB cells expressing FCRL4 wt (filled bars) or “empty vector” control cells (open bars) in the absence of exogenous wt src-family kinase (left panel), or in the presence of HCK p59 (middle panel) or FGR (right panel) were transfected with the firefly luciferase reporter gene under control of the Elk-1 promoter (top row) or under control of an NF-κB–inducible promoter (bottom row) and the Renilla luciferase reporter gene under control of the TK promoter for normalization. For Ag receptor ligations, the cells were pretreated with heat-aggregated IgA. The cells were stimulated for 24 h with the indicated concentrations of anti-IgA/M/G Abs (top row) or CpG (bottom row). (B) HCK p59 and FGR cells expressing “empty vector” (open bars), FCRL4 wt (closed bars), FCRL4 C410A (hatched bars), or FCRL4 FFF (dotted bars) were transfected with the firefly luciferase reporter gene under control of the Elk-1 promoter (top row) or under control of an NF-κB–inducible promoter (bottom row) and the Renilla luciferase reporter gene under control of the TK promoter and stimulated as in (A). Reporter gene activity was normalized to the cotransfected Renilla luciferase reporter gene activity. Values are displayed as mean ± SD from at least 11 independently performed experiments. Statistical significance was assessed using the two-tailed Student t test. *p < 0.05.