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Abstract: FR-PO055

MicroRNA-132 Mediates Tubular Cell Sensitivity and Increases Kidney Injury in Mice

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Gerlach, Cory V., Harvard Medical School, Boston, Massachusetts, United States
  • Lin, Jia-Ren, Harvard Medical School, Boston, Massachusetts, United States
  • Everley, Robert A., Harvard Medical School, Boston, Massachusetts, United States
  • Bonventre, Joseph V., Brigham and Women’s Hospital, Boston, Massachusetts, United States
  • Vaidya, Vishal S., Brigham and Women’s Hospital, Boston, Massachusetts, United States
Background

MicroRNAs regulate multiple signaling pathways that can affect disease progression. We previously reported that miR-132 was upregulated in kidney tubular epithelial cells following injury with nephrotoxic chemicals and was positively correlated with kidney injury in mice and humans.

Methods

MiR-132 knockout (KO) mice and wild-type (WT) littermate controls were subjected to folic acid (FA) nephropathy (250 mg/kg, ip). Kidney structure and function was assessed by widely established methods. Cyclic immunofluorescence was conducted to evaluate 21 proteins representing inflammation, proliferation and DNA damage on the same fixed kidney tissue. For mechanistic investigations, tandem mass tag proteomics was conducted and targeted pathways were probed using Human Proximal Tubular Epithelial Cells (HPTECs) transfected with miR-132 mimics or inhibitors.

Results

In miR-132 KO mice, FA injections resulted in 37% less tubular injury and 64% lower levels of blood urea nitrogen after 2 days compared to WT mice (p<0.05). At day 2, tubular cell proliferation, DNA damage and inflammation were also decreased in miR-132 KO mice relative to WT. Interestingly, miR-132 KO and WT mice had similar kidney damage at day 1, demonstrating that miR-132 KO mice recovered more quickly despite less tubular cell proliferation. On the other hand, proteomics revealed that miR-132 overexpression in HPTECs upregulated proteins involved in promoting cell cycle progression. Out of the 9 proteins predicted to be miR-132 targets, RASA1 (inhibitor of Ras) and SOD2 (detoxifier of mitochondrial reactive oxygen species) were confirmed. In HPTECs, overexpression of miR-132 increased cell count by 69% while miR-132 inhibition decreased cell count by 33% (p<0.05). Testing the functional importance of these data in an injury setting, when HPTECs overexpressing miR-132 were treated with cisplatin there was ~2.5-fold increase in cell death (p<0.05).

Conclusion

Upregulation of miR-132 following kidney injury increases the sensitivity of the kidney to further damage. Therefore, inhibition of miR-132 may offer a therapeutic benefit for acute kidney injury and limit the extent of kidney damage.

Funding

  • Other NIH Support