PPL⁺ Cholangiocytes Define a Pro-Regenerative Subset Associated With NRG1-ERBB3-PI3K/AKT Signalling During Liver...

Area of Science:

• Hepatology and Regenerative Medicine
• Molecular Biology
• Cell Biology

Background:

• Chronic biliary injury is a key driver of liver fibrosis.
• Mechanisms of liver injury resolution and hepatocyte regeneration are not fully understood.
• Periplakin (PPL), a cholangiocyte-associated protein, is upregulated during biliary injury but its role in fibrosis and repair is unknown.

Purpose of the Study:

• To investigate the functional role of Periplakin (PPL) in liver fibrosis and repair following chronic biliary injury.
• To identify the specific subset of cholangiocytes involved in liver regeneration and fibrosis resolution.
• To elucidate the molecular mechanisms by which PPL+ cholangiocytes influence hepatocyte proliferation and fibrosis.

Main Methods:

• Single-nucleus RNA sequencing (snRNA-seq) to map PPL expression in mouse liver.
• Generation of hepatic PPL-overexpression and knockdown models using viral vectors (Adenovirus and Adeno-associated virus).
• Isolation and functional assessment of PPL+ and PPL- cholangiocytes through adoptive transfer, co-culture assays, and molecular analyses (qRT-PCR, Western blot, ELISA, IHC).
• Inference of intercellular signaling pathways using CellChat and validation of NRG1-ERBB3-PI3K/AKT signaling in vitro.

Main Results:

• snRNA-seq identified PPL as a marker for a distinct cholangiocyte subset.
• PPL overexpression attenuated DDC-induced liver fibrosis, while PPL knockdown exacerbated it.
• Adoptive transfer of PPL+ cholangiocytes improved liver function, reduced fibrosis, and promoted hepatocyte proliferation.
• PPL+ cholangiocytes were found to activate hepatocytes via the NRG1-ERBB3-PI3K/AKT signaling axis.

Conclusions:

• PPL+ cholangiocytes constitute a pro-regenerative epithelial cell population.
• This subset is associated with reduced liver fibrosis and enhanced hepatocyte proliferation.
• The pro-regenerative function of PPL+ cholangiocytes may involve NRG1-ERBB3-PI3K/AKT signaling, suggesting potential therapeutic targets for liver diseases.