Department of Spine Surgery, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China.
Cell Prolif. 2019 Mar;52(2):e12542. doi: 10.1111/cpr.12542. Epub 2018 Nov 14.
Tumour necrosis factor alpha (TNF-α) expressed by nucleus pulposus cells (NPCs) plays a critical role in intervertebral disc (IVD) degeneration. A key unfolded protein response (UPR) component, X-box binding protein 1 (XBP1) and nuclear factor-kappa B (NF-κB) are essential for cell survival and proliferation. The aim of our study was to elucidate the roles of XBP1 and NF-κB in IVD degeneration (IDD).
Rat NPCs were cultured with TNF-α in the presence or absence of XBP1 and NF-κB-p65 small interfering RNA. The associated genes and proteins were evaluated through quantitative real-time PCR, Western blot analyses and immunofluorescence staining to monitor UPR and NF-κB signalling and identify the regulatory mechanism of p65 by XBP1. Cell counting kit-8 assay, cell cycle analysis and related gene and protein expression were performed to examine the proliferation of NPCs.
The acute exposure of TNF-α accelerated the proliferation of rat NPCs by activating the UPR/XBP1 pathway. XBP1 signalling favoured the phosphorylation and nuclear translocation of p65 subunit of NF-κB. The activation of NF-κB in the later phase also enhanced NPC proliferation.
Unfolded protein response reinforces the survival and proliferation of NPCs under TNF-α stimulation by activating the XBP1 pathway, and NF-κB serves as a vital mediator in these events. The XBP1 signalling of UPR can be a novel therapeutic target in IDD.
核内体蛋白细胞（NPC）中表达的肿瘤坏死因子-α（TNF-α）在椎间盘退变（IDD）中起着关键作用。未折叠蛋白反应（UPR）的一个关键组成部分，X 盒结合蛋白 1（XBP1）和核因子-κB（NF-κB）是细胞存活和增殖所必需的。本研究的目的是阐明 XBP1 和 NF-κB 在 IDD 中的作用。
用 TNF-α在存在或不存在 XBP1 和 NF-κB-p65 小干扰 RNA 的情况下培养大鼠 NPC。通过定量实时 PCR、Western blot 分析和免疫荧光染色评估相关基因和蛋白，以监测 UPR 和 NF-κB 信号，并确定 XBP1 对 p65 的调节机制。通过细胞计数试剂盒-8 测定、细胞周期分析以及相关基因和蛋白表达，研究 NPC 的增殖情况。
TNF-α 的急性暴露通过激活 UPR/XBP1 通路加速了大鼠 NPC 的增殖。XBP1 信号通路促进了 NF-κB p65 亚基的磷酸化和核转位。后期 NF-κB 的激活也增强了 NPC 的增殖。
未折叠蛋白反应通过激活 XBP1 通路增强 NPC 在 TNF-α刺激下的存活和增殖，NF-κB 是这些事件的重要介质。UPR 的 XBP1 信号通路可能成为 IDD 的一个新的治疗靶点。
