We also analyzed the
SAA1 gene region because of the prominent upregulation of
SAA1 mRNA induced by DEX treatment (
Table 1), and a previous report showing recombinant SAA protein-induced elevation of IOP in human ocular perfusion organ culture.
29 We found that CpG sites within the promoter regions of the
SAA1 gene were demethylated in lot 2584 TM cells (
Fig. 4, top left arrow, the β-value was decreased 18% by DEX treatment) and also were demethylated in lot 3423 (
Fig. 4, middle left arrowhead, the β-value was decreased 8% by DEX treatment), although they did not reach to the cutoff value of our study (10% alteration of the β-value during DEX treatment). Prominent upregulation of
SAA1 mRNA expression was observed with 5-aza-dC treatment under DEX stimulation (
Fig. 4, middle lane), and even without DEX stimulation (
Fig. 4, right lane). These results suggested strong dependency of the
SAA1 transcription machinery on the demethylated status of DNA. The insufficient numbers of CpG probes within the
SAA1 promoter region hindered the detection of significant DNA demethylation in lot 4973, so we are now investigating the DNA methylation status of the
SAA1 promoter region more precisely by analyzing bisulfite sequences data. Our results were consistent with a report showing increased
SAA1 mRNA expression and a decrease of DNA methylation in the
SAA1 promoter region in colonic biopsy samples obtained from ulcerative colitis patients compared to control samples.
30