Fas-Associated Factor 1 Promotes Hepatic Insulin Resistance via JNK Signaling Pathway

Area of Science:

• Cellular biology
• Metabolic disorders
• Molecular mechanisms

Background:

• Fas-associated factor 1 (FAF1) interacts with various proteins, but its role in hepatic metabolic disorder and insulin resistance is unknown.
• Hepatic insulin resistance is a critical component of metabolic disorders, impacting liver function and glucose homeostasis.

Purpose of the Study:

• To investigate the role and molecular mechanism of FAF1 in hepatic insulin resistance.
• To determine if FAF1 influences key metabolic pathways and oxidative stress in the liver.

Main Methods:

• Utilized high-fat diet-induced insulin resistance rat models.
• Assessed FAF1 expression via qPCR, immunohistochemistry, and immunofluorescence.
• Quantified ROS production, lipid accumulation, and glucose uptake using flow cytometry.
• Investigated protein-protein interactions using immunoprecipitation and Western blotting.

Main Results:

• FAF1 expression is significantly increased in insulin-resistant rat livers.
• FAF1 overexpression worsened insulin resistance, upregulated gluconeogenesis, downregulated glucose transport, and increased ROS production.
• FAF1 directly interacts with and phosphorylates c-Jun N-terminal kinase (JNK), inhibiting downstream insulin signaling.
• FAF1 downregulation reversed these detrimental effects, improving insulin sensitivity.

Conclusions:

• FAF1 acts as a key regulator in the development of hepatic insulin resistance and metabolic disorder.
• FAF1-mediated JNK activation is a crucial mechanism underlying its role in insulin resistance.
• Targeting FAF1 may offer a therapeutic strategy for managing hepatic metabolic dysfunction.