Figure 4. The GC box in the Hdc PE is critical for histamine synthesis and IgE/mast cell-mediated anaphylaxis.

A. mice deficient in GC box (GGGCGG) were generated by a single sgRNA (underlined) targeting the GC box located from−48 to −43 in the proximal promoter of the Hdc gene. B. qPCR analysis of Hdc and Gabpb1 mRNA expression in cells isolated from Hdc^GCbox+/+ and Hdc^GC−/− mice (n=4, pooled from two experiments). C. histamine contents in BMMCs derived from Hdc^GCbox+/+ and Hdc^GC−/− mice (n=6, two experiments). D. PSA of Hdc^GCbox+/+ and Hdc^GC−/− mice (n=6, two experiments). E. histamine release in the plasma of Hdc^GCbox+/+ and Hdc^GC−/− mice that were treated with IgE anti-TNP antibody followed by challenge with BSA-TNP. Blood was drawn five minutes after challenge (n=6, two experiments). F. MMCP1 concentrations in the sera of Hdc^GCbox+/+ and Hdc^GC−/− mice that were treated with IgE anti-TNP antibody and BSA-TNP for one hour (n=6, two experiments). P values were calculated using the Mann-Whitney U test.