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Abstract: FR-PO116

miR299a-5p Is a Pathogenic Driver of Renal Fibrosis in CKD

Session Information

Category: Glomerular Diseases

  • 1201 Glomerular Diseases: Fibrosis and Extracellular Matrix

Authors

  • Mehta, Neel, McMaster University, Hamilton, Ontario, Canada
  • Zhang, Dan, St. Joseph's Hospital, Hamilton, Ontario, Canada
  • He, Juehua, McMaster University, Hamilton, Ontario, Canada
  • Gao, Bo, St. Joseph's Hospital, Hamilton, Ontario, Canada
  • Krepinsky, Joan C., McMaster University, Hamilton, Ontario, Canada
Background

Chronic kidney disease (CKD) is a major cause of morbidity and mortality. It is characterized by glomerular and interstitial fibrosis. Glomerular mesangial cells (MCs) are a major contributor to glomerular fibrosis. Previously, we identified that caveolin-1 (cav-1) is required for basal and TGFβ1-induced MC synthesis of matrix proteins. The protective phenotype of cav-1 knockout (KO) MCs against fibrosis is associated with increased expression of a TGFβ family member neutralizing protein, follistatin (FST). To better understand the mechanism of FST upregulation and identify novel therapeutic targets, we performed a quantitative screen in cav-1 wild-type (WT) and KO MCs to identify differentially regulated miRNAs that bind to and regulate the 3’UTR of FST.

Methods

In vitro studies were carried out in primary MCs isolated from cav-1 WT and KO mice using standard molecular biology techniques. For in vivo studies, a 9-week 5/6 nephrectomy (5/6 Nx) mouse model of CKD was used.

Results

Expression and activity of miR299a-5p was significantly decreased in KO MCs which express high levels of FST. We confirmed that miR299a-5p regulates the 3’UTR of FST. In KO cells, FST downregulation increased TGFβ1-induced matrix synthesis. We thus examined whether miR299a-5p regulated this process. In WT MCs, TGFβ1 increased miR299-5p expression and downregulated FST, while exogenous FST reduced TGFβ1-induced matrix synthesis. Importantly, downregulation of miR299a-5p increased FST expression and decreased TGFβ1-induced matrix synthesis. Conversely, in KO cells, overexpression of miR299a-5p decreased FST expression and enhanced TGFβ1-induced matrix synthesis. These data demonstrate that miR299a-5p suppression of FST expression augments ECM production in response to TGFβ1, a key contributor to the pathogenesis of CKD. In the 5/6 Nx mouse model of CKD, we further identified significantly elevated expression of both TGFβ1 and miR299a-5p.

Conclusion

miR299a-5p expression is increased in the kidneys of mice with CKD. miR299a-5p augments TGFβ1-induced ECM production in glomerular MCs through downregulation of the antifibrotic protein FST. These data suggest that miR299a-5p plays a pathogenic role in the development and progression of renal fibrosis. Its inhibition thus represents a potential novel therapeutic target for the treatment of CKD.

Funding

  • Government Support - Non-U.S.