Site-specific ubiquitination of VDAC1 restricts its oligomerization and mitochondrial DNA release in liver fibrosis
Related Experiment Video
Updated: Aug 13, 2025
Isolation of Primary Mouse Hepatocytes for Nascent Protein Synthesis Analysis by Non-radioactive L-azidohomoalanine Labeling Method
Published on: October 23, 2018
Ne N Wu1,2, Lifeng Wang3, Lu Wang4,5
1Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital Fudan University, Shanghai, 200032, China.
Abstract:
Mitochondrial DNA (mtDNA) released through protein oligomers, such as voltage-dependent anion channel 1 (VDAC1), triggers innate immune activation and thus contributes to liver fibrosis. Here, we investigated the role of Parkin, an important regulator of mitochondria, and its regulation of VDAC1-mediated mtDNA release in liver fibrosis. The circulating mitochondrial DNA (mtDNA) and protein levels of liver Parkin and VDAC1 were upregulated in patients with liver fibrosis. A 4-week CCl4 challenge induced release of mtDNA, activation of STING signaling, a decline in autophagy, and apoptosis in mouse livers, and the knockout of Parkin aggravated these effects. In addition, Parkin reduced mtDNA release and prevented VDAC1 oligomerization in a manner dependent on its E3 activity in hepatocytes. We found that site-specific ubiquitination of VDAC1 at lysine 53 by Parkin interrupted VDAC1 oligomerization and prevented mtDNA release into the cytoplasm under stress. The ubiquitination-defective VDAC1 K53R mutant predominantly formed oligomers that resisted suppression by Parkin. Hepatocytes expressing VDAC1 K53R exhibited mtDNA release and thus activated the STING signaling pathway in hepatic stellate cells, and this effect could not be abolished by Parkin. We propose that the ubiquitination of VDAC1 at a specific site by Parkin confers protection against liver fibrosis by interrupting VDAC1 oligomerization and mtDNA release.
Insights
Parkin protein prevents liver fibrosis by inhibiting mitochondrial DNA release. It achieves this by modifying the VDAC1 protein, stopping harmful inflammatory responses and protecting liver cells.
Area of Science:
- Biochemistry
- Cell Biology
- Immunology
Background:
- Mitochondrial DNA (mtDNA) release activates innate immunity, contributing to liver fibrosis.
- Protein oligomers, like VDAC1, facilitate mtDNA release.
- Parkin is a key regulator of mitochondria.
Purpose of the Study:
- Investigate Parkin's role in regulating VDAC1-mediated mtDNA release in liver fibrosis.
- Determine Parkin's mechanism of action in preventing liver fibrosis.
Main Methods:
- Analysis of mtDNA and protein levels in human liver fibrosis patients.
- CCl4-induced liver fibrosis model in mice with and without Parkin.
- Assessment of VDAC1 oligomerization, mtDNA release, STING signaling, autophagy, and apoptosis.
- Site-directed mutagenesis of VDAC1 (K53R) to study ubiquitination effects.
Main Results:
- Parkin and VDAC1 levels were elevated in human liver fibrosis.
- Parkin deficiency exacerbated CCl4-induced liver injury, mtDNA release, STING activation, autophagy decline, and apoptosis.
- Parkin inhibited mtDNA release and VDAC1 oligomerization via its E3 ligase activity.
- Parkin-mediated ubiquitination of VDAC1 at Lys53 prevented oligomerization and mtDNA release.
- A ubiquitination-defective VDAC1 mutant (K53R) promoted mtDNA release and STING activation, independent of Parkin.
Conclusions:
- Parkin ubiquitination of VDAC1 at Lys53 is a protective mechanism against liver fibrosis.
- This modification interrupts VDAC1 oligomerization and subsequent mtDNA release, thereby mitigating innate immune activation and liver damage.
More Related Videos
08:56Bile Duct Ligation in Mice: Induction of Inflammatory Liver Injury and Fibrosis by Obstructive Cholestasis
Published on: February 10, 2015
08:27Visualization and Quantification of Endogenous Intra-Organelle Protein Interactions at ER-Mitochondria Contact Sites by Proximity Ligation Assays
Published on: October 20, 2023
