MicroRNA-489 Induction by Hypoxia-Inducible Factor-1 Protects against Ischemic Kidney Injury
Qingqing Wei1, Yong Liu2, Pengyuan Liu2
1Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University and Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia; zdong@gru.edu 30912.qwei@gru.edu.
Abstract:
MicroRNAs have been implicated in ischemic AKI. However, the specific microRNA species that regulates ischemic kidney injury remains unidentified. Our previous microarray analysis revealed microRNA-489 induction in kidneys of mice subjected to renal ischemia-reperfusion. In this study, we verified the induction of microRNA-489 during ischemic AKI in mice and further examined the underlying mechanisms. Hypoxia-inducible factor-1α deficiency associated with diminished microRNA-489 induction in cultured rat proximal tubular cells subjected to hypoxia and kidney tissues of mice after renal ischemia-reperfusion injury. Moreover, genomic analysis revealed that microRNA-489 is intronic in the calcitonin receptor gene, and chromatin immunoprecipitation assays showed increased binding of hypoxia-inducible factor-1 to a specific site in the calcitonin receptor gene promoter after hypoxia. Inhibition of microRNA-489 increased apoptosis in renal tubular cells after ATP depletion injury in vitro, whereas microRNA-489 mimics mediated protection. In mice, inhibition of microRNA-489 enhanced tubular cell death and ischemic AKI without significantly affecting tubular cell proliferation. Deep sequencing identified 417 mRNAs that were recruited to the RNA-induced silencing complex by microRNA-489. Of the identified mRNAs, 127 contain microRNA-489 targeting sites, and of those, 18 are involved in the cellular stress response, including the poly(ADP-ribose) polymerase 1 gene implicated in ischemic kidney injury. Sequence analysis and in vitro studies validated poly(ADP-ribose) polymerase 1 as a microRNA-489 target. Together, these results suggest that microRNA-489 is induced via hypoxia-inducible factor-1 during ischemic AKI to protect kidneys by targeting relevant genes.
Insights
MicroRNA-489 protects kidneys during ischemic acute kidney injury (AKI) by targeting stress response genes. Its induction, mediated by hypoxia-inducible factor-1, is crucial for kidney protection.
Area of Science:
- Nephrology
- Molecular Biology
- Genetics
Background:
- MicroRNAs (miRNAs) play roles in ischemic acute kidney injury (AKI), but specific regulatory miRNAs are unknown.
- Previous microarray analysis identified microRNA-489 (miR-489) induction in renal ischemia-reperfusion injury.
- The precise function and regulatory mechanisms of miR-489 in ischemic AKI require elucidation.
Purpose of the Study:
- To verify miR-489 induction in ischemic AKI.
- To investigate the regulatory mechanisms of miR-489 induction.
- To determine the functional role of miR-489 in renal tubular cell injury and protection.
Main Methods:
- Microarray analysis, hypoxia-inducible factor-1α (HIF-1α) deficiency models, genomic analysis, chromatin immunoprecipitation assays.
- In vitro studies using cultured rat proximal tubular cells with ATP depletion and miR-489 mimics/inhibitors.
- In vivo studies in mice subjected to renal ischemia-reperfusion injury, followed by deep sequencing and target validation.
Main Results:
- miR-489 was induced during ischemic AKI in mice, with diminished induction in HIF-1α deficient cells/tissues.
- HIF-1α binds to the calcitonin receptor gene promoter, regulating miR-489 transcription.
- Inhibition of miR-489 exacerbated tubular cell apoptosis and AKI, while mimics conferred protection.
- Deep sequencing identified 417 target mRNAs, including poly(ADP-ribose) polymerase 1 (PARP1), a validated target involved in cellular stress.
Conclusions:
- miR-489 is induced by HIF-1α during ischemic AKI.
- miR-489 protects renal tubular cells from injury by targeting genes like PARP1.
- miR-489 represents a potential therapeutic target for ischemic AKI.
