Figure 4. A SNP in the OTX2 binding site 3 decreases the activity of the human TYR promoter. A–C: The T-223C (rs4547091) mutation (marked here as SNP) was introduced to reporters containing the TYR promoter fragments Enh./-2525 and −462. The wild-type and mutated reporters and −462m3 or −462m123 plasmids were transfected into ARPE-19, bovine (bRPE), and human fetal primary RPE (fhRPE) cells with MITF-A or OTX2 factors, their combination, or an empty expression vector (pCR3). Data are means±SEM from two independent transfections performed in triplicate or quadruplicate. D: The endogenous expression of tyrosinase, MITF-A, and OTX2 mRNA in fhRPE cells was measured at time point 48 h. Mean normalized expression±SEM are shown relative to 48 h ARPE-19 culture (=100) from two independent cultures each performed in triplicate.