Figure 4.

The promoter methylation level of CDH1 is not significantly changed in human epithelial cells derived from normal donors and those with COPD. (A) Top: The schematic diagram displays the percentage of cytosine–guanine dinucleotide (CpG) dinucleotide (CG) content in the 5′ promoter region of the CDH1. In an in silico analysis by MethPrimer, four CpG islands (CGIs) were identified (blue) (CG content >60%, an observed:expected ratio = 0.6). Bottom: The average methylation percentage (% Met) of the CDH1 promoter is shown among CGIs. % Met was calculated by taking an average of the methylation level of all CpG sites within CGI1, CGI2, and CGI3 and CGI4 of 3 normal donors (N) and 3 with COPD (C) by bisulfite sequencing. (B) The % Met of individual CpG sites at the CDH1 promoter (6–10 clones per donor). (C and D) Chromatin immunoprecipitation of (C) RNA polymerase II (RNAPII) and (D) histone H3 monomethylated at lysine 4 (H3K4 me1) at the TSS region (5 normal donors and 5 with COPD). Error bars represent SEM. Statistics were determined using (A) Wilcoxon matched-pairs signed rank tests and (C and D) the Mann–Whitney test, with P < 0.05 considered statistically significant. TSS = transcription start site; UTR = untranslated region.