Urinary miR-16 transactivated by C/EBPβ reduces kidney function after ischemia/reperfusion-induced injury

Ischemia-reperfusion (I/R) induced acute kidney injury (AKI) is regulated by transcriptional factors and microRNAs (miRs). However, modulation of miRs by transcriptional factors has not been characterized in AKI. Here, we found that urinary miR-16 was 100-fold higher in AKI patients. MiR-16 was detected earlier than creatinine in mouse after I/R. Using TargetScan, the 3'UTR of B-cell lymphoma 2 (BCL-2) was found complementary to miR-16 to decrease the fluorescent reporter activity. Overexpression of miR16 in mice significantly attenuated renal function and increased TUNEL activity in epithelium tubule cells. The CCAAT enhancer binding protein beta (C/EBP-beta) increased the expression of miR-16 after I/R injury. The ChIP and luciferase promoter assay indicated that about -1.0 kb to -0.5 kb upstream of miR-16 genome promoter region containing C/EBP-beta binding motif transcriptionally regulated miR-16 expression. Meanwhile, the level of pri-miR-16 was higher in mice infected with lentivirus containing C/EBP-beta compared with wild-type (WT) mice and overexpression of C/EBP-beta in the kidney of WT mice reduced kidney function, increased kidney apoptosis, and elevated urinary miR-16 level. Our results indicated that miR-16 was transactivated by C/EBP-beta resulting in aggravated I/R induced AKI and that urinary miR-16 may serve as a potential biomarker for AKI.