Parthenolide Alleviates Peritoneal Fibrosis by Blocking Smad2/3 Phosphorylation via Smad Anchor for Receptor...

Area of Science:

• Nephrology
• Cell Biology
• Molecular Biology

Background:

• Progressive peritoneal fibrosis is a severe complication of peritoneal dialysis (PD).
• The transforming growth factor (TGF)-β/Smad pathway is implicated in fibrosis.
• The role of Smad anchor for receptor activation (SARA) in PD-associated fibrosis is unclear.

Purpose of the Study:

• To elucidate the role of SARA in PD-associated peritoneal fibrosis.
• To investigate the relationship between parthenolide (PTL) and SARA.
• To determine the mechanism by which PTL alleviates peritoneal fibrosis.

Main Methods:

• Single-cell sequencing (scRNA-seq) data analysis.
• Collection and analysis of long-dwell PD fluid samples.
• Establishment of PD mouse models, TGF-β1-induced mesothelial-mesenchymal transition (MMT) models, and CRISPR/Cas9-engineered SARA gene (ZFYVE9) knockout cell lines.
• In vitro and in vivo coimmunoprecipitation experiments, molecular docking, and PTL-biotin pulldown assays.

Main Results:

• SARA activates Smad2/3, and Smad3 promotes SARA degradation, leading to decreased SARA expression during fibrosis progression.
• PTL inhibits the SARA-Smad3 interaction without affecting SARA protein stability.
• PTL directly binds to SARA at the Smad3-binding interface (Pro788 and Ser795 residues).

Conclusions:

• SARA promotes PD-related peritoneal fibrosis by phosphorylating Smad2/3.
• PTL alleviates peritoneal fibrosis by specifically binding to SARA (ZFYVE9) and disrupting the SARA-Smad3 interaction.
• This mechanism restores SARA expression, improves MMT, and offers a theoretical basis for clinical treatment of peritoneal fibrosis.