Kidney Week

Abstract: SA-PO340

miR-17/-20a Alleviates Renal Interstitial Fibrosis by Repressing Frmd6 Expression in Renal Epithelia

Session Information

• Development, Organoids, Vascularized Kidneys, Nephrons, and More
  November 04, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Development, Stem Cells, and Regenerative Medicine

• 600 Development, Stem Cells, and Regenerative Medicine

Authors

• Malta C.S Santos, Debora, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, United States

Debora Malta C.S Santos,

• Tayeb, Maliha, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, United States

Maliha Tayeb,

• Bodnar, Andrew J., Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, United States

Andrew J. Bodnar,

• Appolonia, Corynn, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, United States

Corynn Appolonia,

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

Roderick J. Tan,

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

Arohan R. Subramanya,

• Bitzer, Markus, University of Michigan Department of Internal Medicine, Ann Arbor, Michigan, United States

Markus Bitzer,

• Ho, Jacqueline, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, United States

Jacqueline Ho,

Background

An estimated 37 million Americans have chronic kidney disease (CKD), and its prevalence is increasing with higher rates of diabetes mellitus, hypertension and obesity. Regardless of the underlying etiology, renal fibrosis is the final manifestation of CKD. microRNAs (miRNAs) are endogenous, small non-coding RNAs that bind to target mRNAs and regulate their expression. In this study, we investigated the role of the miR-17~92 cluster (comprises miR-17, -18a, -19a, -19b, -20a and -92a) in renal fibrosis.

Methods

Genetic mouse models of inducible epithelial-specific miR-17~92 loss-of-function (imiR-17~92^EpiLOF) or gain-of-function (imiR-17~92^EpiGOF) were generated by crossing Pax8Cre-rtTA; LC1-cre mice with miR-17~92 floxed mice or with a mouse line containing a constitutively active CAG promoter ahead of a loxP-flanked STOP cassette preventing transcription of the downstream miR-17~92 sequence, respectively. Unilateral ureteral obstruction (UUO) and acute kidney injury (AKI) to CKD model were performed. Renal fibrosis was assessed by immunostaining with anti-collagen III and anti-α-SMA antibodies, followed by semi-quantitative analyses with ImageJ. The human proximal tubular epithelial cell line HK2 was transfected with either empty vector or a vector containing the Frmd6 cDNA. HK2 cells were used for experimental identification of miR-17~92 target genes using PAR-CLIP.

Results

miRs-17, -18a, and -20a were upregulated in UUO and the AKI to CKD model. Interestingly, imiR-17~92^EpiLOF mice exhibited increased predisposition to renal fibrosis with aging and after UUO, which was accompanied by increased expression of known miR-17~92 profibrotic targets, p-Stat3 and p-Smad3. Conversely, UUO-induced fibrosis was ameliorated in imiR-17~92^EpiGOF kidneys. 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. Finally, overexpression of Frmd6 in HK2 cells resulted in increased expression of the mesenchymal markers SNAI1 and FN1, and elevated secretion of collagen III in conditioned media.

Conclusion

Together, our findings indicate that the miR-17~92 cluster in renal epithelia functions to limit fibrosis by regulating multiple pro-fibrotic pathways.

Funding

• NIDDK Support