Kidney Week

Abstract: TH-PO1090

Repression of Frmd6 Expression by miR-17/-20a in the Renal Epithelium Mitigates Interstitial Fibrosis

Session Information

• CKD: Mechanisms - 1
  October 24, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

• 2303 CKD (Non-Dialysis): Mechanisms

Authors

• Malta C.S Santos, Debora, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Debora Malta C.S Santos, PhD

• Tayeb, Maliha, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Maliha Tayeb

• Bodnar, Andrew J., University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Andrew J. Bodnar

• O'Connor, Christopher Lund, University of Michigan, Ann Arbor, Michigan, United States

Christopher Lund O'Connor

• Zhang, Huanqing, University of Michigan, Ann Arbor, Michigan, United States

Huanqing Zhang, MD, PhD

• Appolonia, Corynn, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Corynn Appolonia

• Rush, Brittney M., University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Brittney M. Rush

• Tan, Roderick J., University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Roderick J. Tan, MD, PhD

• Subramanya, Arohan R., University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Arohan R. Subramanya, MD, FASN

• Turner, David L., University of Michigan, Ann Arbor, Michigan, United States

David L. Turner, PhD

• Bitzer, Markus, University of Michigan, Ann Arbor, Michigan, United States

Markus Bitzer, MD

• Ho, Jacqueline, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Jacqueline Ho, MD, MS

Background

Chronic kidney disease (CKD) is characterized by a progressive decline in kidney function, and renal fibrosis is an essential part of the pathophysiological mechanism underlying disease progression. In this study, we investigated the role of the miR-17~92 microRNA (miRNA) cluster in renal fibrosis. This cluster generates a single polycistronic primary transcript that yields six mature miRNAs (miR-17, -18a, -19a, -19b, -20a, and -92a).

Methods

Unilateral ureteral obstruction (UUO) and acute kidney injury (AKI) to CKD model were used as models of renal fibrosis. To investigate the potential role of miR-17~92 as an anti-fibrotic molecule, genetic mouse models of inducible Pax8 lineage-specific deletion (imiR-17~92^EpiLOF) and gain-of-function (imiR-17~92^EpiGOF) of miR-17~92 were generated. Protein expression was assessed by immunostaining in mouse kidneys and human nephrectomy samples from the PRECISE cohort, which includes patients with CKD stages 1 and 2. PAR-CLIP was performed in the human proximal tubular epithelial cell line HK2 treated or not with TGFβ1 to identify potential miR-17~92 targets, which were then validated by dual luciferase reporter assays in HEK293 cells. HK2 cells were transfected with either an empty vector or a vector containing the Frmd6 cDNA.

Results

miRs-17, -18a, and -20a were upregulated in UUO and the AKI to CKD model. Interestingly, UUO-induced fibrosis was exacerbated in imiR-17~92^EpiLOF mice but ameliorated in imiR-17~92^EpiGOF mice. Frmd6, an activator of Hippo signaling, was identified as a novel miR-17/-20a target. Frmd6 was increased in the tubular epithelium of obstructed imiR-17~92^EpiLOF kidneys compared to controls. Furthermore, augmented Frmd6 was associated with regions of human nephrectomy samples with increased collagen III deposition. Finally, overexpression of Frmd6 in HK2 cells resulted in increased expression of the COPII secretory pathway component, Sec31, and was accompanied by elevated secretion of collagen III in conditioned media.

Conclusion

Together, our findings indicate that the epithelial-derived miR-17~92 limits collagen deposition during renal fibrosis by regulating Frmd6 expression.

Funding

• NIDDK Support