Role of the mitochondrial calcium uniporter in Mg²⁺-free-induced epileptic hippocampal neuronal apoptosis

Abstract

Purpose

Mitochondrial Ca²⁺ overload is closely associated with seizure-induced neuronal damage. The mitochondrial calcium uniporter (MCU) plays a crucial role in regulating mitochondrial Ca²⁺ homeostasis. However, the role of the MCU in seizure-induced neuronal damage remains elusive.

Materials and methods: In this study, the hippocampal neuronal culture (HNC) model of acquired epilepsy (AE) was used to investigate the role of the MCU in seizure-induced neuronal injury.

Results: We found an increase in mitochondrial Ca²⁺ concentration in the HNC model of AE. The MCU inhibitor, Ru360, significantly reduced the rate of seizure-induced cell apoptosis and mitochondrial reactive oxygen species (ROS) production; whereas, the MCU agonist, spermine, exacerbated these processes. In addition, Ru360 significantly attenuated seizure-induced endoplasmic reticulum (ER) stress, which is characterized by the expression of glucose-regulated protein 78 (GRP78) and C/-EBP homologous protein (CHOP), while spermine had the opposite effect. We also found that pre-treatment with the mitochondria-targeted antioxidant, mitoquinone, decreased GRP78 and CHOP expression. Moreover, knockdown of CHOP using CHOP-specific small interfering RNA reduced neuronal seizure-induced apoptosis.

Conclusions: Taken together, our data indicate that MCU inhibition has a neuroprotective effect against seizure-induced neuronal damage and that this mechanism may involve reduction of ROS-mediated ER stress.

Keywords:

• Mitochondrial calcium uniporter
• endoplasmic reticulum stress
• oxidative stress
• epilepsy
• calcium

Acknowledgements

Conceived and designed the experiments: Nanchang Xie; Performed the experiments: Yingjiao Li, Mengyan Yu, Xianghe Meng, Yujuan Li; Analyzed the data: Nanchang Xie, Cui Wang, Yajun Lian, Haifeng, Zhang; Wrote the manuscript: Nanchang Xie, Yingjiao Li.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Compliance with ethical standards

The authors have no conflicts of interest to declare.

Research involving animals.

Ethical approval

“All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.”

Additional information

Funding

This study was supported by grants from National Natural Science Foundation of China (No.81971214, 81701272) and Provincial Ministry Co-construction Project from Medical Scientific and Technological Research Program of Henan Province (SB201902011).