Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Mazowiecka 5, 92-215 Lodz, Poland.
Int J Mol Sci. 2024 Jul 12;25(14):7679. doi: 10.3390/ijms25147679.
Parkinson's disease (PD) is a neurodegenerative disorder which affects dopaminergic neurons of the midbrain. Accumulation of α-synuclein or exposure to neurotoxins like 6-hydroxydopamine (6-OHDA) induces endoplasmic reticulum (ER) stress along with the unfolded protein response (UPR), which executes apoptosis via activation of PERK/CHOP or IRE1/JNK signaling. The present study aimed to determine which of these pathways is a major contributor to neurodegeneration in an 6-OHDA-induced in vitro model of PD. For this purpose, we have applied pharmacological PERK and JNK inhibitors (AMG44 and JNK V) in differentiated SH-SY5Y cells exposed to 6-OHDA. Inhibition of PERK and JNK significantly decreased genotoxicity and improved mitochondrial respiration, but only JNK inhibition significantly increased cell viability. Gene expression analysis revealed that the effect of JNK inhibition was dependent on a decrease in and mRNA levels, whereas inhibition of either PERK or JNK significantly reduced the expression of mRNA. Western blot has shown that JNK inhibition strongly induced the XBP1s protein, and inhibition of each pathway attenuated the phosphorylation of eIF2α and JNK, as well as the expression of CHOP. Collectively, our data suggests that targeting the IRE1/JNK pathway of the UPR is a more effective option for PD treatment as it simultaneously affects more than one pro-apoptotic pathway.
帕金森病（PD）是一种神经退行性疾病，影响中脑的多巴胺能神经元。α-突触核蛋白的积累或暴露于神经毒素如 6-羟多巴胺（6-OHDA）会引起内质网（ER）应激和未折叠蛋白反应（UPR），通过 PERK/CHOP 或 IRE1/JNK 信号通路激活执行细胞凋亡。本研究旨在确定在 6-OHDA 诱导的体外 PD 模型中，这些通路中的哪一种是导致神经退行性变的主要因素。为此，我们在暴露于 6-OHDA 的分化 SH-SY5Y 细胞中应用了 PERK 和 JNK 的药理学抑制剂（AMG44 和 JNK V）。PERK 和 JNK 的抑制显著降低了遗传毒性并改善了线粒体呼吸，但只有 JNK 的抑制显著增加了细胞活力。基因表达分析显示，JNK 抑制的作用依赖于 和 mRNA 水平的降低，而 PERK 或 JNK 的抑制均显著降低了 mRNA 的表达。Western blot 表明，JNK 抑制强烈诱导 XBP1s 蛋白，并且抑制每条途径均减弱了 eIF2α 和 JNK 的磷酸化以及 CHOP 的表达。总之，我们的数据表明，靶向 UPR 的 IRE1/JNK 途径是 PD 治疗的更有效选择，因为它同时影响多种促凋亡途径。
