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Abstract: TH-PO539

The Balance Between STAT3 and Glutathione Metabolism Is Required for Parietal Cell Activation and Proliferation in Proliferative Glomerulopathies

Session Information

Category: Glomerular Diseases

  • 1401 Glomerular Diseases: From Inflammation to Fibrosis

Authors

  • Kim, Joseph, Stony Brook University Hospital, Stony Brook, New York, United States
  • Gowthaman, Yogesh, Stony Brook University Hospital, Stony Brook, New York, United States
  • Guo, Yiqing, Stony Brook University Hospital, Stony Brook, New York, United States
  • Bronstein, Robert, Stony Brook University Hospital, Stony Brook, New York, United States
  • Chow, Andrew, Stony Brook University Hospital, Stony Brook, New York, United States
  • Mallipattu, Sandeep K., Stony Brook University Hospital, Stony Brook, New York, United States
Background

STAT3 signaling is activated in podocytes and parietal epithelial cells (PECs) in murine models of proliferative glomerulopathy and in human RPGN and subtypes of FSGS. We previously showed that podocyte-specific loss of STAT3 preserves podocyte loss and attenuates PEC activation. However, the mechanism by which STAT3 activation triggers PEC activation, proliferation, and crescent formation and whether its inhibition as a therapeutic target in proliferative glomerulopathies remains poorly understood.

Methods

PECs were treated with increasing doses of IL-6 (5, 10, 20, 40ng/ml) to explore the role of STAT3 activation in cell viability. We generated mouse PECs with deletion of STAT3 using Crispr/Cas9. MTT assay was performed on Cas9 (wildtype) and STAT3 knockout (STAT3-/-) PECs. Cell migration of Cas9 and C7 cells were measured using a scratch assay. Mitochondrial respiration, glycolytic rate, and ATP production were performed using seahorse analyzer. Glutathione, superoxide, and reactive oxygen species (ROS) levels were measured. RNA sequencing was conducted in the Cas9 and STAT3-/- PECs. PEC-specific STAT3-/- mice were generated as well as STAT3 inhibitor treatment in mice post-nephrotoxic serum (NTS) administration.

Results

STAT3-/- PECs exhibited reduced cell proliferation, activation, oxygen consumption, and ATP production. RNAseq demonstrated a downregulation of differential expressed genes (DEGs) involved in glutathione metabolism with an upregulation in focal adhesion DEGs. STAT3-/- PECs had reduced cellular glutathione pool leading to increased levels of superoxide levels leading to increased oxidative stress and DHE expression. In silico analysis showed that pSTAT3 occupies the promoter region of key glutathione synthesis genes, suggesting potential direct regulation. PEC-specific STAT3-/- mice or treatment with STAT3 inhibitor reduced proteinuria, PEC activation (CD44, Akap12), crescent formation with increased oxidative stress (8-oxo-G, OGG1) as compared to their respective controls post-NTS treatment.

Conclusion

To date, this is the first study to demonstrate the mechanism by which STAT3 activation in PECs enhances glutathione metabolism to maintain a balance in ROS and exacerbate PEC activation and crescent formation in proliferative glomerulopathies.

Funding

  • NIDDK Support