Dznep, a histone modification inhibitor, inhibits HIF1α binding to TIMP2 gene and suppresses TIMP2 expression under hypoxia

Epidemiological studies have shown that patients who recovered from acute kidney injury (AKI) may subsequently develop chronic kidney disease (CKD). AKI is primarily caused by renal hypoxia, and it causes epigenetic alterations, known as hypoxic memory. 3‐Deazaneplanocin A (Dznep), an inhibitor of histone modification, suppresses renal fibrosis and the expression of tissue inhibitor of metalloproteinases‐2 (TIMP2), a profibrotic factor, in mouse ischemia–reperfusion models. The current study investigated the epigenetic regulation of TIMP2 in human kidney 2 (HK‐2) cells. The expression of TIMP2 was upregulated in HK‐2 cells under hypoxic conditions and was suppressed by Dznep. ChIP‐qPCR showed that Dznep reduced the amount of H3K4me3 at the promoter region of the TIMP2 gene under hypoxic condition. Formaldehyde‐assisted isolation of regulatory elements‐qPCR of the TIMP2 gene showed that Dznep reduced open chromatin area. In addition, based on ChIP‐qPCR of hypoxia‐inducible factor 1 alpha (HIF1α), Dznep inhibited the binding of HIF1α to the TIMP2 gene under hypoxic conditions. The reporter assays for the binding region of HIF1α showed enhanced transcriptional activity by hypoxia. Dznep suppresses the expression of TIMP2 under hypoxic conditions by inhibiting the binding of HIF1α to the TIMP2 gene.