New Protein Target Could Unlock FGF21's Power Against Fatty Liver Disease

This groundbreaking research reveals how FGF21, a promising therapeutic hormone, protects against metabolic dysfunction-associated steatohepatitis (MASH) - a severe form of fatty liver disease that can progress to cirrhosis and liver cancer. Understanding this mechanism is crucial as MASH affects millions worldwide with limited treatment options.

Scientists used liver-specific knockout mice and two different diet models to study MASH development. They fed mice either an AMLN diet for 16 weeks or a choline-deficient high-fat diet for 8 weeks, then treated them with FGF21 or placebo. Mass spectrometry identified PPP6C as a key FGF21-binding protein.

The study revealed that FGF21 works by activating protein phosphatase 6 (PPP6C), which directly interacts with the FGF21 receptor complex. PPP6C then removes phosphate groups from TSC2 protein at specific sites, effectively shutting down mTORC1 - a cellular pathway that promotes inflammation and liver damage when overactive. This allows beneficial proteins TFE3 and Lipin1 to enter cell nuclei and promote healing.

Crucially, when researchers removed PPP6C from mouse livers, FGF21 completely lost its protective effects against MASH. Human liver samples from MASH patients confirmed the clinical relevance, showing decreased PPP6C levels and increased harmful TSC2 phosphorylation compared to healthy controls.

These findings explain why FGF21 analogs show promise in clinical trials and suggest PPP6C could become a new drug target. However, this research was conducted primarily in mice, and human studies are needed to confirm therapeutic potential.