Abstract: TH-PO1130
Disruption of PPP1R3G-PP1γ Interaction by Deletion or Pharmacologic Inhibition Mitigates Kidney Fibrosis Progression
Session Information
- CKD: Mechanisms, AKI, and Beyond - 1
November 06, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: CKD (Non-Dialysis)
- 2303 CKD (Non-Dialysis): Mechanisms
Authors
- Rani, Alka, University of South Florida Morsani College of Medicine, Tampa, Florida, United States
- Tran, Minh Hoang, University of South Florida Morsani College of Medicine, Tampa, Florida, United States
- Parris, Colby Lucien, University of South Florida Morsani College of Medicine, Tampa, Florida, United States
- Esquivel, Carlos R, University of South Florida Morsani College of Medicine, Tampa, Florida, United States
- Oropeza, Andrea, University of South Florida Morsani College of Medicine, Tampa, Florida, United States
- Wang, Lei, University of South Florida Morsani College of Medicine, Tampa, Florida, United States
Background
Crosstalk between dying tubular cells and inflammation is a key driver of kidney fibrosis. Necroptosis, a type of programmed cell death involving receptor-interacting protein kinase 1 (RIPK1), plays a major role in this process. Protein phosphatase 1 regulatory subunit 3G (PPP1R3G) collaborates with protein phosphatase 1γ (PP1γ) to regulate kinase activity, but its role in RIPK1 activation and tubular cell death during fibrosis development remains unknown.
Methods
Fibrosis was induced both in primary proximal tubular cells (PTCs) using TGF-β and in vivo using the reversible unilateral ureteral obstruction (RUUO) model in wild-type and Ppp1r3g-/- mice. Cell viability, cell death, kidney injury, fibrosis, and renal function were assessed. The phosphorylation status of RIPK1 and NLRP3 inflammasome formation were analyzed using RT-PCR and Western blotting, and these findings were correlated with the extent of kidney fibrosis and functional decline. Additionally, compounds designed to disrupt the PPP1R3G/PP1γ interaction were synthesized and tested in kidney fibrosis models.
Results
Renal cellular injury increases PPP1R3G expression and activates the RIPK1-mediated necroptosis pathway. Deletion of PPP1R3G significantly attenuated tubular cell death, reduced necroptosis markers (phospho-RIPK1, RIPK3, and MLKL), suppressed inflammatory responses, and led to marked reductions in kidney injury and fibrosis, evidenced by approximately 85% of KO cells survival from fibrosis, while only 36% of WT cells exhibited survival under the same conditions and a 62% reduction in plasma creatinine (0.74±0.16 mg/dl vs. 0.87 ± 0.18 mg/dL, p<0.001, n=5) and a 46% increase in GFR (n=5). Histological analysis confirmed decreased necroptosis and interstitial fibrosis in the Ppp1r3g-/- mice. Peptide inhibitors, PGB-1, effectively blocked RIPK1-dependent tubular cell death by disrupting the PPP1R3G–PP1γ interaction. PGB-1 treatment reduced fibrosis signals and improved kidney function, lowering plasma creatinine by 74% compared to the untreated group.
Conclusion
This study reveals that PPP1R3G-mediated necroptosis significantly contributes to kidney fibrosis progression and that disrupting the PPP1R3G/PP1γ interaction with PGB-1 is a promising therapeutic intervention for human chronic kidney disease.
Funding
- NIDDK Support