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Abstract: FR-PO153

miRNA Profiling of Kidney Disease Indicates a Conserved Role for miRNA99 Family

Session Information

Category: Glomerular Diseases

  • 1201 Glomerular Diseases: Fibrosis and Extracellular Matrix

Authors

  • Raman, Archana, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Miguel, Verónica, CBMSO, Madrid, Spain
  • Qiu, Chengxiang, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Park, Jihwan, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Huang, Shizheng, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Susztak, Katalin, University of Pennsylvania, Philadelphia, Pennsylvania, United States

Group or Team Name

  • Susztaklab
Background

MicroRNAs (miRNAs) are short non-coding RNA molecules that play a crucial role in cellular homeostasis by regulating gene expression. Lately, miRNAs have become important therapeutic targets. To determine consistently altered miRNAs that could causally affect chronic kidney disease (CKD) development, we sought to define miRNA profiles in kidneys of five different CKD models and validated these results in patient samples.

Methods

miRNA fraction was isolated from the kidneys of wildtype mice or mice with CKD induced by 1) unilateral ureteral obstruction (UUO), 2) folic acid (FA) administration, 3) transgenic expression of Notch intracellular domain in tubule cells, 4) transgenic expression of PGC1α in podocytes and 5) transgenic expression of APOL1 risk allele in podocytes. Small RNA sequencing was followed by miRNA alignment and abundance quantification. qPCR analysis and in situ hybridization were used to validate candidate miRNAs differentially expressed in CKD. We used microRNA mimics and inhibitors to understand the role of miRNA in cultured renal tubule cells.

Results

We detected differences in levels of 457 miRNAs among all analyzed models of kidney disease. miR-99 family consisting of 99a, 99b and 100, were significantly downregulated in all five models. In situ hybridization for miR-99 family on wildtype, UUO, and FA kidney sections showed that these miRNAs were expressed widely in normal tubules but absent or significantly downregulated in injured/dedifferentiated tubules. Importantly, human renal biopsy sections also showed significant downregulation in the expression of the miR-99 family in CKD patients, compared to healthy volunteers. Furthermore, transfection of HKC8, a human proximal tubule cell line, with miR-99a and 100 mimics improved epithelial characteristics and reduced proliferation. We identified IGF1 and mTOR as likely targets of miR-99 family in kidney tubule samples.

Conclusion

We found that miR-99a, 99b and 100 are significantly downregulated across all examined CKD models and human subjects, implying a causal role in disease. Upregulation of miR-99 family in vitro significantly decreased expression of mTOR, IGF-1, cell proliferation and improved epithelial characteristics, suggesting a crucial regulatory function. In summary, miR-99 family could be potential therapeutic targets for CKD.

Funding

  • NIDDK Support