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Abstract: TH-PO539

Differential Alterations of Hippo Signaling Pathway in Kidney Cells After Unilateral Ureteral Obstruction

Session Information

  • Pathology and Lab Medicine
    November 03, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pathology and Lab Medicine

  • 1700 Pathology and Lab Medicine

Authors

  • Zhang, Yaochun, National University of Singapore, Singapore, Singapore
  • Li, Zhenhua, National University of Singapore, Singapore, Singapore
  • Lu, Liangjian, National University of Singapore, Singapore, Singapore
  • Ahmad, Nurul Jannah Binti, National University of Singapore, Singapore, Singapore
  • Chan, Chang-Yien, National University of Singapore, Singapore, Singapore
  • Ng, Jun Li, National University of Singapore, Singapore, Singapore
  • Yap, Hui Kim, National University of Singapore, Singapore, Singapore
  • Ng, Kar Hui, National University of Singapore, Singapore, Singapore
Background

The Hippo signaling pathway regulates physiological functions. Renal fibrosis enhances nuclear translocation of the Hippo signalling effectors YAP/TAZ. We previously analyzed single cell RNA sequencing (scRNA-Seq) databases and observed heterogeneity in Hippo signaling activation status in different kidney cells. Here, we aimed to study the differential alterations of Hippo signaling in kidney cell clusters after unilateral ureteral obstruction (UUO), a process which causes fibrosis.

Methods

Ligation of left ureters was performed in rats. The kidneys were harvested after 7 days’ obstruction (UUO7) and cell transcriptomics were profiled with RNA-Seq. Separately, publicly available single-cell transcriptomics of UUO2, UUO7 and wild-type mice (GEO: GSE140023) were re-analyzed with Seurat v4.0. Gene Set Enrichment Analysis (GSEA) was performed with evolutionary conserved YAP target genes to compare the Hippo pathway activation status in UUO and normal states. Cellular distributions of YAP were confirmed with immunohistochemistry.

Results

The UUO kidneys displayed extensive tubular dilation. Intense Yap nuclear localization was observed in all dilated tubules and some medullary interstitial cells. GSEA revealed upregulation of Yap target genes (NES = 1.50, P = 0.02) in UUO rats. scRNA-Seq on the UUO2 mouse kidneys showed significant upregulation of Yap target genes in five kidney cell clusters, namely podocytes, cluster 5 (PT5) and cluster 9 (PT9) of proximal tubular cells (PT), principal cells of collecting duct and epithelial cells of inner medullary collecting duct. In contrast, only PT5 was upregulated in UUO7 kidneys. Additionally, two other cell clusters, PT1 and the distal convoluted tubular cells, showed significant upregulation of Yap target genes. Interestingly, while the evolutionary conserved gene set was upregulated in PT7, PT8, PT9, thick ascending limb and endothelial cells in UUO2, it was downregulated in UUO7, though these were not significant.

Conclusion

The Hippo signalling pathway was differentially altered in kidney cells after UUO. Different trends in some cell clusters between UUO2 and UUO7 mice may imply the Hippo signaling pathway exert different effects in the acute and chronic phases of ureteral obstruction.

Funding

  • Government Support – Non-U.S.