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Kidney Week

Abstract: PO2242

Plasminogen Activator Inhibitor 1 (PAI-1) Induction During Kidney Injury Promotes Epithelial Dysfunction via TGF-β1 Receptor Signaling and Klotho Downregulation

Session Information

Category: Pathology and Lab Medicine

  • 1601 Pathology and Lab Medicine: Basic

Authors

  • Gifford, Cody Charles, Albany Medical College, Albany, New York, United States
  • Lian, Fei, Albany Medical College, Albany, New York, United States
  • Tang, Jiaqi, Albany Medical College, Albany, New York, United States
  • Costello, Angelica, Albany Medical College, Albany, New York, United States
  • Goldschmeding, Roel, Department of Pathology, University Medical Center Utrecht, Utrecht, Netherlands
  • Samarakoon, Rohan, Albany Medical College, Albany, New York, United States
  • Higgins, Paul J., Albany Medical College, Albany, New York, United States
Background

Persistent PAI-1 induction is evident in several nephropathies in mice and humans. Although PAI-1 is an established CKD promoting factor, the precise role of PAI-1 in disease progression is unclear and, surprisingly, this fibrogenic response appears to be mediated by uPA-independent mechanisms. Expression of the anti-aging gene klotho is lost during renal injury, predisposing to CKD, and recombinant klotho administration in mice suppresses progressive fibrosis. Whether kidney tubular PAI-1 induction promotes maladaptive repair and orchestrates klotho downregulation is currently unknown.

Methods

To mimic sustained renal epithelial PAI-1 expression during renal injury, we stably expressed PAI-1 via lentiviral transduction in HK2 human kidney epithelial cells (CMV-PAI-1); western blotting confirmed PAI-1 overexpression relative to vector controls (CMV-Con). Double-transgenic cells engineered to express both PAI-1 and klotho were used to assess pathological interplay between PAI-1 and klotho in renal fibrosis.

Results

PAI-1 expressing HK-2 cells robustly upregulated pro-fibrotic factor expression/secretion (fibronectin and collagen-1) and exhibited dedifferentiation (loss of E-cadherin and increased vimentin expression), G2/M growth arrest and susceptibility to apoptosis, evident by increases in pHistone-H-3, pH2AX, p21 and p53 expression, caspase3 cleavage and annexin V-positivity compared to the CMV-Con population. PAI-1-transductants had increased TGF-β receptor 1/2 levels and SMAD2/3 activation relative to vector controls. TGF-β1 receptor-1 kinase inhibition with SB431542 attenuated the PAI-1-driven fibrotic phenotype, independent of TGF-β1 ligand synthesis. Interestingly, sustained PAI-1 expression also downregulated klotho protein levels compared to controls. Rescue of klotho expression in CMV-PAI-1 cells attenuated fibrogenesis and reversed the proliferative arrest.

Conclusion

Persistent PAI-1 expression promotes a fibrotic maladaptive repair orchestrated, in part, via TGF-β1-receptor1/2 hyperactivity and klotho loss. Our studies identify not only a novel role for PAI-1 in renal tubular dysfunction but also in klotho deregulation in renal fibrosis.

Funding

  • Other NIH Support