We have previously reported that the kidney- and liver-specific expression of transporters in mice involve the coordinated regulation by Hepatocyte Nuclear Factor (HNF) 1 and DNA methylation. The present study was aimed at investigating the role of this cascade in the transcriptional regulation of renal organic anion transporters yet to be characterized in human and mouse. Luciferase assays and electrophoretic mobility shift assays demonstrated that HNF1α/β enhances the promoter activity of Organic Anion Transporter (OAT) 4/SLC22A11 via binding to the HNF1-motif located nearby the transcriptional start site (TSS). DNA methylation profiles of human OAT1, OAT3, OAT4 and URAT1 were determined in human liver and kidney cortex by bisulfite sequencing. Most of the CpG dinucleotides around the TSSs of OAT1 and OAT3 were highly methylated in the liver compared with kidney cortex, being consistent with their tissue specificity, while the difference in the DNA methylation status was less remarkable between the two tissues for OAT4 and URAT1. Mouse Oat1 gene also contained CpG dinucleotides hypomethylated in the kidney and hypermethylated in the liver downstream its TSS, whereas two of the seven CpG dinucleotides around the TSS of mouse Oat3 were significantly methylated in the liver compared with the kidney. Taken together, these findings underscored the central role of HNF1α/β in the transcriptional regulation of OATs and highlighted DNA methylation-dependent gene silencing as one of the mechanisms underlying the tissue-specific transactivation by this master regulator.
- Received August 21, 2011.
- Revision received November 20, 2011.
- Accepted November 28, 2011.
- The American Society for Pharmacology and Experimental Therapeutics