Background
Ischemic reperfusion injury of kidney is major cause for renal failure, however the involved pathogenesis remains unclear creating an void for its effective treatment. Here we studied involvement of microRNA-424 in renal injury.
Conclusion
The study confirmed p53/miR-424/DR6 as a protective cascade during ischemic-reperfusion injury.
Methods
For the study, p53 or HIF-1α mice were used, ischemic renal injury was induced using clamping of renal pedicles bilateraly. Proximal kidney tubular cells were used for in vitro studies. Hoechst 33342 analysis was done for apoptosis. Blood urea nitrogen (BUN) and serum creatinine was done for renal function, Hematoxylin-eosin tissue damage and Terminal transferase-dUTP nick-end labeling assay for apoptosis. RT-PCR was done for miRNA and ChIP assay to identify the binding of p53 to miR-424. TargetScan and miRanda data base were scanned to find targets of miR-424. Protein expression was done by western blot analysis.
Results
We discovered that, miR-424 was over-expressed in ischemic renal injury mice and in hypoxia exposed renal cells. In cells, miR-424 suppressed the expression levels of death receptor 6 (DR6) and halted the apoptosis mediated by hypoxia. Blocking of miR-424 halted the inhibition of DR6 and caused apoptosis and activation of caspase. In mice, miR-424 mimic inhibited expression of DR6 and attenuated ischemic renal injury. We established that, up-regulation of miR-424 in ischemic reperfusion injury was p53 dependent, also inhibition of p53 caused repression of miR-424 levels in hypoxia induced cells in vitro. The p53 knockout mice showed attenuation in levels of miR-424 confirming role of p53 behind up-regulation of miR-424 in vivo.