Impact of UCP2 depletion on heat stroke-induced mitochondrial function in human umbilical vein endothelial cells

Abstract

Objective

The incidence rate of heat stroke (HS) has increased, with high morbidity and mortality rates, in recent years. Previous studies have suggested that vascular endothelial cell injury is one of the main pathological features of HS. Uncoupling protein 2 (UCP2) exhibits antioxidant activity under various stress conditions. This study aims to investigate the role of UCP2 in HS-induced vascular endothelial injury.

Method

To explore the mechanisms mediating vascular endothelial cell injury induced by HS, we established an HS model of HUVECs in vitro. The percentage of cell death and viability induced by HS were assessed using annexin V-FITC/PI staining and CCK8 assays. HS-induced mitochondrial membrane potential (ΔΨm) was detected by JC-1 staining. HS-induced mitochondrial superoxide was measured by MitoSOX staining, and analyzed by flow cytometry. UCP2, Drp1, phosphorylated Drp1, OPA1, and Mfn2 expression levels were measured by western blotting.

Results

HS triggered mitochondrial fragmentation and UCP2 upregulation in a time-dependent manner in HUVECs. As a specific Drp1 inhibitor, Mdivi‐1 pretreatment significantly promoted mitochondrial fission and apoptosis in HS-induced HUVECs. In addition, siRNA-mediated UCP2 knockdown further aggravated mitochondrial fragmentation and ΔΨm depolarization and increased mitochondrial ROS production and cell apoptosis in HS-induced HUVECs, which were abolished by Drp1 inhibition.

Conclusion

Our results indicate that UCP2 protects against HS-induced vascular endothelial damage and that it enhances mitochondrial function. These findings reveal that UCP2 can be a potential contributor to mechanism-based therapeutic strategies for HS.

Keywords:

• Heat stress
• UCP2
• Drp1
• mitochondrial dysfunction
• pulmonary microvascular endothelial cells

Author contributions

Wei Huang and Liangfeng Mao were responsible for primary data generation and the composition of this manuscript. Weidang Xie and Sumin Cai performed all the experiments. Qiaobing Huang and Zhongqing Chen acquired and interpreted the data. Yanan Liu and Chen confirmed the authenticity of the raw data. All authors analyzed the data, and reviewed and approved the final manuscript.

Disclosure statement

No potential conflict of interest is reported by the authors.

Additional information

Funding

This work was supported by research grants from the National Nature Science Fund of China [grant numbers 81701955, 81871604, and 82172181].