Podocyte-specific KLF4 is required to maintain parietal epithelial cell quiescence in the kidney

Abstract

Podocyte loss triggering aberrant activation and proliferation of parietal epithelial cells (PECs) is a central pathogenic event in proliferative glomerulopathies. Podocyte-specific Krüppel-like factor 4 (KLF4), a zinc-finger transcription factor, is essential for maintaining podocyte homeostasis and PEC quiescence. Using mice with podocyte-specific knockdown of Klf4, we conducted glomerular RNA-sequencing, tandem mass spectrometry, and single-nucleus RNA-sequencing to identify cell-specific transcriptional changes that trigger PEC activation due to podocyte loss. Integration with in silico chromatin immunoprecipitation identified key ligand-receptor interactions, such as fibronectin 1 (FN1)-V6, between podocytes and PECs dependent on KLF4 and downstream signal transducer and activator of transcription 3 (STAT3) signaling. Knockdown of Itgb6 in PECs attenuated PEC activation. Additionally, podocyte-specific induction of human KLF4 or pharmacological inhibition of downstream STAT3 activation reduced FN1 and integrin  6 (ITGB6) expression and mitigated podocyte loss and PEC activation in mice. Targeting podocyte-PEC crosstalk might be a critical therapeutic strategy in proliferative glomerulopathies.

The Pathology Lesion Patterns of Podocytopathies: How and why?

“…Lineage tracing by genetic tagging employing both podocyte and PEC-specific reporter mice in a model mimicking CG finally proved that hyperplastic cells were not podocyte-derived, but of PEC origin ( Suzuki et al, 2009 ). Moreover, a recent multiomics study reported that podocyte-specific knockdown of Krüppel-like factor 4 contributes to podocyte loss triggering the activation of a distinct PEC subpopulation, suggesting that in this disorder PEC proliferation and pseudocrescent formation represent a response to podocyte injury and loss ( Pace et al, 2021 ).…”

Comparison of human recombinant protein coatings and fibroblast-ECM to Matrigel for induced pluripotent stem cell culture and renal podocyte differentiation

“…The majority of pluripotent markers in iPSC-derived podocytes showed low to no mRNA expression. Two exceptions were PODXL and KLF4 that both showed clear expression that remained consistent across all coating in the podocyte-like cells, this is expected as both genes play important roles in the formation and function of podocytes (Refaeli et al, 2020, Pace et al, 2021. Interestingly, KLF4, one of the Yamanaka factors used for the reprogramming of iPSCs (Takahashi and Yamanaka, 2006), showed a much higher difference in mRNA expression levels in undifferentiated iPSC, with a significantly greater expression for all three cell lines when cultured on fibroblast-ECM compared to any of the other coatings, including Geltrex (Figure 4).…”

The Role of Parietal Epithelial Cells in the Pathogenesis of Podocytopathy

“…By using RNA-sequencing, mass spectrometry, and single-cell RNA-sequencing, Pace et al have identified key ligand-receptor interactions between podocytes and PECs via KLF4/STAT3 signaling. Restoration of KLF4 expression in podocytes or inhibition of STAT3 signaling prevented the loss of podocytes and suppressed PEC activation in mice ( Pace et al, 2021 ).…”