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Ethanol-triggered Lipophagy Requires SQSTM1 in AML12 Hepatic Cells
Lin Wang1,2,3,4, Jun Zhou1,5, Shengmin Yan1
1Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
Scientific Reports
|September 28, 2017
Summary
Ethanol elevates liver cell lipids, but autophagy, mediated by SQSTM1/p62, helps clear them. This study reveals how SQSTM1 guides autophagosomes to lipid droplets, protecting against liver injury.
Area of Science:
- Cell Biology
- Hepatology
- Autophagy Research
Background:
- Ethanol-induced liver injury is a significant health concern.
- Lipophagy, the autophagic breakdown of lipids, is a protective mechanism against liver damage.
- The precise molecular mechanisms regulating ethanol-induced lipophagy remain incompletely understood.
Purpose of the Study:
- To elucidate the mechanism by which ethanol induces lipophagy in hepatocytes.
- To investigate the role of the adaptor protein SQSTM1/p62 in ethanol-induced lipophagy.
- To explore the interaction between SQSTM1/p62, lipid droplets, and the autophagy machinery.
Main Methods:
- Utilized an immortalized mouse hepatocyte cell line (AML12).
- Investigated the effects of ethanol treatment on cellular lipid content and autophagy markers (LC3, SQSTM1).
- Employed knockdown strategies for SQSTM1 and perilipin1, followed by colocalization studies using immunofluorescence.
Main Results:
- Ethanol treatment increased lipid content in hepatocytes, which was modulated by autophagy.
- SQSTM1/p62 and LC3 colocalized with lipid droplets (LDs) upon ethanol exposure.
- SQSTM1 knockdown inhibited LC3-LD colocalization and reduced ethanol-induced lipid accumulation.
- Ubiquitin signals and perilipin1 were found to colocalize with SQSTM1 on LDs, and perilipin1 knockdown affected lipophagy.
Conclusions:
- Ethanol induces lipophagy in hepatocytes through a mechanism involving the adaptor protein SQSTM1/p62.
- SQSTM1 facilitates the targeting of autophagosomes to LDs by binding to ubiquitinated proteins, potentially including perilipin1.
- This pathway represents a key cytoprotective mechanism against ethanol-induced liver injury.
