NLRX1 accelerates cisplatin-induced ototoxity in HEI-OC1 cells via promoting generation of ROS and activation of JNK signaling pathway

Haiyan Yin,Qi Qi,Qianqian Yang,Gaoying Sun,Jianfeng Li,Chen Chen,Haibo Wang

doi:10.1038/srep44311

Haiyan Yin, Qi Qi + Show 5 more

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https://doi.org/10.1038/srep44311

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Abstract

Nucleotide-binding domain and leucine-rich-repeat-containing family member X1 (NLRX1), located in mitochondria, can recognize cytoplasmic pattern recognition receptors and is tightly related to reactive oxygen species (ROS) production, mitochondrial function, apoptosis and inflammation. The present study was designed to explore whether NLRX1 expresses in HEI-OC1 cells and, if so, to investigate the possible correlations between NLRX1 and cisplatin-induced ototoxity in vitro. Here, we report that NLRX1 was specifically localized to mitochondria in the cytoplasm of HEI-OC1 cells and its expression was increased concurrent with the increase of ROS production and occurrence of apoptosis in HEI-OC1 cells in response to cisplatin stimulus. NLRX1 overexpression led to a higher apoptosis in HEI-OC1 cells treated with cisplatin, whereas, NLRX silencing decreased cisplatin induced apoptosis. Mechanistic studies showed that NLRX1 activated mitochondrial apoptosis pathway as well as promoted ROS generation and JNK activation. Either inhibition of ROS generation or JNK signaling significantly prevented NLRX1-mediated mitochondrial apoptosis in HEI-OC1cells. In addition, NLRX1 expression was confirmed in cochlear explants. The findings from this work reveal that NLRX1 sensitizes HEI-OC1 cells to cisplatin-induced apoptosis via activation of ROS/JNK signaling pathway, suggesting that NLRX1 acts as an important regulator of the cisplatin-elicited ototoxity.

Highlights

Cisplatin, the chemotherapeutic agent widely used in the treatment of a broad spectrum of tumors[1], is limited in its clinical application due to its severe side effects, including the ototoxicity and nephrotoxicity[2]
We observed the punctate expression of Nucleotide-binding domain and leucine-rich-repeat-containing family member X1 (NLRX1) in cytoplasm of the HEI-OC1 cells and NLRX1 was localized to mitochondria (Fig. 1a)
Similar NLRX1 expression was observed in HEK-293 cells, which was served as the positive control of NLRX1 expression

Summary

Introduction

The chemotherapeutic agent widely used in the treatment of a broad spectrum of tumors[1], is limited in its clinical application due to its severe side effects, including the ototoxicity and nephrotoxicity[2]. Except for mediating inflammation, recent studies have suggested that NLRX1 could regulate virus-induced autophagy and ROS production, mitochondrial function, cell death, and carcinogenesis[12,13,14,15]. We propose that under the condition of cisplatin stress, the survival of cochlea cells may be affected by altered NLRX1 via regulating ROS/JNK pathways associated with cell death. To test this hypothesis, the present study was designed to explore the effects of NLRX1 on auditory model HEI-OC1 cells, a conditionally immortalized cochlear cell line derived from the mouse organ of Corti[30], treated with cisplatin, and to elucidate the underlying mechanisms

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