Oleate inhibits hepatic autophagy through p38 mitogen-activated protein kinase (MAPK)

Area of Science:

• Cell Biology
• Metabolic Disease Research
• Molecular Mechanisms

Background:

• Hepatic autophagy is crucial for lipid metabolism, particularly in nonalcoholic fatty liver disease (NAFLD).
• The precise relationship between oleic acid and hepatic autophagy remains incompletely understood.
• Investigating this interaction is vital for understanding NAFLD pathogenesis.

Purpose of the Study:

• To investigate the role of oleic acid in regulating hepatic autophagy.
• To elucidate the molecular mechanisms underlying oleic acid's effects on autophagy.
• To explore potential therapeutic targets for NAFLD related to autophagy.

Main Methods:

• Utilized mouse epithelial cell line (hepa1c1c7) for experimental studies.
• Assessed autophagy markers such as LC3 accumulation and p62 protein expression.
• Quantified mRNA levels of key autophagy-related genes (ATG7, BECN1, ULK1).
• Employed p38 kinase inhibitors (SB203580) and dominant-negative p38α to explore signaling pathways.
• Investigated transcription factor activation (ATF-2) and promoter activity (ULK1).

Main Results:

• Oleic acid exposure significantly reduced LC3 accumulation and increased p62 protein expression in hepatic cells.
• mRNA levels of ATG7 and BECN1 were decreased following oleic acid treatment.
• The inhibitory effect of oleic acid on autophagy was blocked by p38 pathway inhibitors.
• Oleic acid activated ATF-2, a downstream target of p38 kinase.
• Oleic acid inhibited the ULK1 promoter, leading to decreased ULK1 mRNA levels.

Conclusions:

• Oleic acid suppresses hepatic autophagy through a mechanism involving the p38/ATF-2 pathway.
• This pathway activation leads to the inhibition of ULK1, ultimately suppressing autophagy.
• Findings provide novel insights into the molecular regulation of hepatic autophagy by fatty acids and its implications for NAFLD.