Liver ASK1 protects from non-alcoholic fatty liver disease and fibrosis

Area of Science:

• Hepatology
• Molecular Biology
• Cellular Biology

Background:

• Non-alcoholic fatty liver disease (NAFLD) is linked to obesity and can advance to non-alcoholic steatohepatitis (NASH) and liver fibrosis.
• Limited pharmacological treatments for NASH and fibrosis stem from a poor understanding of their pathological pathways.

Purpose of the Study:

• To investigate the role of apoptosis signal-regulating kinase 1 (ASK1) in the pathogenesis of NASH and liver fibrosis.
• To identify ASK1 as a potential therapeutic target for NAFLD and related liver conditions.

Main Methods:

• Utilized liver-specific ASK1-knockout and overexpression mouse models.
• Administered high-fat diets and carbon tetrachloride to induce liver disease.
• Assessed hepatic steatosis, inflammation, and fibrosis.
• Examined the impact of pharmacological ASK1 inhibition and modulation of autophagy.
• Correlated ASK1 expression with liver fat and NASH scores in human liver samples.

Main Results:

• Liver-specific ASK1 knockout mice exhibited exacerbated hepatic steatosis, inflammation, and fibrosis.
• ASK1 inhibition led to increased hepatic lipid accumulation in wild-type mice.
• ASK1 overexpression protected against diet-induced steatosis and fibrosis.
• ASK1 depletion impaired autophagy, promoting lipid accumulation and fibrosis.
• Human liver studies revealed an inverse correlation between ASK1 expression and liver fat/NASH scores, and a positive correlation with autophagy markers.

Conclusions:

• Apoptosis signal-regulating kinase 1 (ASK1) acts as a suppressor of NASH and liver fibrosis.
• ASK1 plays a crucial role in maintaining liver health by regulating autophagy and lipid metabolism.
• ASK1 represents a promising novel therapeutic target for treating NAFLD and liver fibrosis.