Mutation of the N1 motif increases basal promoter activity in COL2A1 and COMP promoters. (A) RCS cells were transiently transfected (in triplicate experiments) with either wild-type COL2A1 human promoter (COL2A1-WT) or the mutated (COL2A1-N1Del) promoter-luciferase reporter constructs in the presence (+) or absence (−) of IL1B, to evaluate the cis-regulatory function of the predicted N1 motif. The core sequence (underlined) in the N1 motif (CCAGTGCCC) was deleted to CCA----CC. (B) RCS cells were transfected with wild-type (COMP-WT) or mutant (COMP-N1Mut) COMP luciferase-reporter promoter constructs (human). The N1 motif in COMP promoter was converted from CACCACAGCCC to CACTGTGGCCC to form N1Mut (the mutational changes are underlined). Luciferase activity was normalized as described in Methods.
