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HMGB1 release by H2O2-induced hepatocytes is regulated through calcium overload and 58-F interference
Pei Zhao1, Tingjie Ye2, Xiaofeng Yan2
1The Public Experiment Platform, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
Insights
Hydrogen peroxide (H2O2) causes liver injury by disrupting calcium homeostasis and releasing High Mobility Group Box 1 (HMGB1). The flavanone 58-F protects hepatocytes by inhibiting this pathway and reducing HMGB1 release.
Area of Science:
- Cellular Biology
- Biochemistry
- Toxicology
Background:
- High Mobility Group Box 1 (HMGB1) release exacerbates inflammation and is implicated in H2O2-induced cell injury.
- Calcium overload is also a key mediator of H2O2-induced cellular damage.
- The interplay between HMGB1 release and calcium overload in H2O2 injury was previously unclear.
Purpose of the Study:
- To investigate the mechanism of calcium overload during H2O2-induced hepatocyte injury.
- To elucidate how extracellular HMGB1 release is regulated by calcium overload.
- To evaluate the therapeutic potential of 58-F, a flavanone from *Ophiopogon japonicus*, in mitigating H2O2-induced liver injury.
Main Methods:
- Utilized H2O2-induced hepatocytes as an experimental model.
- Investigated the role of the PLCγ1-IP3R-SOC signaling pathway in calcium homeostasis.
- Assessed the activation and translocation of calcium-dependent enzymes (PKCα and CaMKIV).
- Monitored HMGB1 phosphorylation, nuclear-to-cytoplasmic translocation, and extracellular release.
- Evaluated the effects of 58-F on cellular calcium levels and HMGB1 release.
Main Results:
- The PLCγ1-IP3R-SOC signaling pathway was identified as a key player in H2O2-induced calcium overload in hepatocytes.
- Increased intracellular calcium activated PKCα and CaMKIV, leading to HMGB1 phosphorylation.
- Phosphorylated HMGB1 translocated from the nucleus to the cytoplasm and was subsequently released extracellularly.
- 58-F treatment effectively suppressed the PLCγ1-IP3R-SOC pathway, reduced intracellular calcium, and inhibited HMGB1 release.
Conclusions:
- H2O2-induced hepatocyte injury involves calcium overload mediated by the PLCγ1-IP3R-SOC pathway.
- Calcium overload triggers a signaling cascade involving PKCα and CaMKIV that promotes HMGB1 release.
- 58-F demonstrates therapeutic potential by targeting this pathway, offering a novel strategy for treating H2O2-induced liver damage.
Abstract:
HMGB1 is passively released by injured or dying cells and aggravates inflammatory processes. The release of HMGB1 and calcium overload have each been reported to be important mediators of H2O2-induced injury. However, a potential connection between these two processes remains to be elucidated. In the present study, we employed H2O2-induced hepatocytes to investigate how calcium overload takes place during cellular injury and how the extracellular release of HMGB1 is regulated by this overload. In addition, we investigated the use of 58-F, a flavanone extracted from Ophiopogon japonicus, as a potential therapeutic drug. We show that the PLCγ1-IP3R-SOC signalling pathway participates in the H2O2-induced disturbance of calcium homoeostasis and leads to calcium overload in hepatocytes. After a rise in intracellular calcium, two calcium-dependent enzymes, PKCα and CaMKIV, are activated and translocated from the cytoplasm to the nucleus to modify HMGB1 phosphorylation. In turn, this promotes HMGB1 translocation from the nucleus to the cytoplasm and subsequent extracellular release. 58-F effectively rescued the hepatocytes by suppressing the PLCγ1-IP3R-SOC signalling pathway and decreasing the calcium concentration in cells, thus reducing HMGB1 release.