Fig. 3

Transcriptional inhibition of KIBRA promoters by in vitro methylation. a Schematic representation of KIBRA promoters P1a and P1b, CpG islands, and respective positions of methylated promoter constructs generated in the CpG-free pCpGL-Basic vector. b In renal IHKE cells, transcriptional activity of promoter P1a was extensively silenced by SssI methylation. No considerable differences were observed for transcriptional activity of control region P1bII (without CpG island). Transcriptional activity of promoter portion P1bI was significantly decreased. Partial methylation by HpaII also resulted in a significant decrease of P1a transcriptional activity, whereas P1bI was unaffected. c Transcriptional activity of P1a was comparably silenced by SssI methylation in neuronal SH-SY5Y cells. Partial methylation by HpaII resulted in an increase of transcriptional activity of promoter region P1aII, whereas transcriptional activity of P1aI was significantly decreased. None of the P1b promoter constructs exerted sufficient activity in SH-SY5Y cells, independent of the methylation pattern. Figures are representative for experiments (n = 3). Transcriptional activity was assessed as relative light units (RLU). ***p < 0.001, ns not significant