IRE1\u03b1 siRNA relieves endoplasmic reticulum stress-induced apoptosis and alleviates diabetic peripheral neuropathy in vivo and in vitro

Weijie Yao,Xinwei Yang,Liping Xu,Biane Gao,Haotian Shi,Jiayue Zhu

doi:10.1038/s41598-018-20950-9

Weijie Yao, Xinwei Yang + Show 4 more

Open Access

https://doi.org/10.1038/s41598-018-20950-9

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Journal: Scientific Reports	Publication Date: Feb 7, 2018
Citations: 33	License type: open-access

Affiliation: Capital Medical University

Abstract

Diabetic peripheral neuropathy (DPN) is mainly characterized by demyelination resulted from the apoptosis of the Schwann cell (SCs). Although the exact mechanisms underlying DPN remain unclear, endoplasmic reticulum (ER) stress is strongly implicated in the apoptosis. Under ER stress, activated inositol-requiring kinase 1α (IRE1α) unregulated CHOP, phosphorylated JNK and Caspase-12 to aggravate apoptosis-mediated damage of DPN. Therefore, we tested the hypothesis that inhibition of IRE1α could reduce the ER stress-related apoptosis to relieve DPN. Here, we show that IRE1α siRNA improved the neurological morphology and function of DPN rats and rescued ER stress-related apoptosis in the sciatic nerve. Additionally, RSC96 cells transfected with IRE1α siRNA were used as in vitro model of DPN. It was found that IRE1α siRNA also decreased high glucose-induced apoptosis and inhibited ER stress-related apoptosis in the cells. Altogether, our results suggest that IRE1α should be considered a potential therapeutic agent for DPN.

Highlights

Diabetic peripheral neuropathy (DPN), one of the diabetes complications, is a neurodegenerative disease with no treatment options available[1]
Our previous study has demonstrated that Inositol-requiring kinase 1α (IRE1α) is overexpressed in the sciatic nerve of high-carbohydrate/high-fat diet and lowdose STZ-induced DPN rats and this result was further verified in this study (Fig. 1A), where overexpressed IRE1α induced the prolonged endoplasmic reticulum (ER) stress, leading to demyelination and nerve dysfunction[13]
Injected IRE1α siRNA was used to further investigate the IRE1α pathway in DPN. Because this method has not been fully reported in DPN rats, immunofluorescence (IF) staining and Western blotting (WB) were used to examine IRE1α expression in the sciatic nerve. 3 days after injection, IRE1α was reduced to 22% (IF staining) and 24% (WB), respectively, as compared to IRE1α siRNA control-transfected group and to 39% (IF staining) and 44% (WB) in DPN IRE1α siRNA transfected group compared to DPN group (Fig. 1)

Summary

Introduction

Diabetic peripheral neuropathy (DPN), one of the diabetes complications, is a neurodegenerative disease with no treatment options available[1]. Chronic hyperglycemia induces endoplasmic reticulum (ER) stress, which is the key factor leading to the apoptosis of the Schwann cell (SCs), and contributing to DPN3. IRE1α determines cell fate based on ER stress severity. Hyperglycemia and hyperlipidemia in diabetes patients hyperactivate IRE1α and potentiate ER stress-induced apoptosis[6]. This research will focus on the IRE1α pathway in DPN rats and the Schwann cells to investigate whether IRE1α siRNA could relieve DPN as well as the molecular mechanisms underlying ER stress-related apoptosis. In this work we evaluated IRE1α inhibition to decrease the ER stress-induced apoptosis, using experimental models of DPN. We demonstrate that inhibition of IRE1α reduces the CHOP, Caspase-12 and phosphorylated JNK related-apoptosis and decreases the demyelination of DPN, potentially leading to new therapeutic approaches

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