State Key Laboratory of Medical Neurobiology, Shanghai Medical College and Institutes of Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
Neurotox Res. 2013 Aug;24(2):164-75. doi: 10.1007/s12640-013-9375-6. Epub 2013 Jan 15.
RESP18 (Regulated endocrine-specific protein, 18 kDa) was first identified as a dopaminergic drugs-regulated intermediate pituitary transcript. RESP18 protein is a unique endoplasmic reticulum (ER) resident protein. Its functions in the brain especially in the nervous system disorders remain unknown. ER stress (ERS) has been proved to be one of the important pathogenesis of neurodegenerative diseases, including Parkinson's disease (PD). Here, we explored the association of RESP18 and ERS in cell models of PD. Dopaminergic neurotoxin 1-methyl-4-phenyl-pyridinium ion (MPP⁺), 6-hydroxydopamine (6-OHDA), and rotenone evoked dramatic MN9D cell death. The transcriptional expressions of RESP18 and two ERS markers--binding immunoglobulin protein/glucose-regulated protein 78 (BiP/GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP) manifested differential changes in MN9D cells treated with MPP⁺, 6-OHDA, and rotenone. The RESP18 protein levels increased in MPP⁺ and 6-OHDA-treated cells, but did not change in the cells treated with rotenone, while the protein levels of ER molecular chaperone heat shock protein 90 kDa beta member 1/glucose-regulated protein 94 (HSP90B1/GRP94) and BiP in the cells were up-regulated by MPP⁺ and 6-OHDA, respectively. Salubrinal, an ERS inhibitor, significantly reduced MPP⁺ and 6-OHDA-induced cell death. Moreover, ERS inducer--thapsigargin and tunicamycin, decreased the expression of RESP18, which is different from the changes of BiP, GRP94, and CHOP. Silencing RESP18 expression with Lenti-shRNA alleviated MPP⁺-induced cell death, while over-expression of RESP18 resulted in aggravated cell death induced by MPP⁺ and 6-OHDA. Taken together, our results suggest that RESP18 is involved in the cytotoxicity of dopaminergic neurotoxins.
RESP18（调节内分泌特异性蛋白，18kDa）最初被鉴定为多巴胺能药物调节的中间垂体转录物。RESP18 蛋白是一种独特的内质网（ER）驻留蛋白。其在大脑中的功能，特别是在神经系统疾病中的功能尚不清楚。内质网应激（ERS）已被证明是神经退行性疾病（包括帕金森病）的重要发病机制之一。在这里，我们在帕金森病细胞模型中探索了 RESP18 与 ERS 的关联。多巴胺能神经毒素 1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPP⁺）、6-羟多巴胺（6-OHDA）和鱼藤酮引起 MN9D 细胞的剧烈死亡。MPP⁺、6-OHDA 和鱼藤酮处理的 MN9D 细胞中转录表达的 RESP18 和两个 ERS 标志物--结合免疫球蛋白蛋白/葡萄糖调节蛋白 78（BiP/GRP78）和 CCAAT/增强子结合蛋白同源蛋白（CHOP）表现出不同的变化。RESP18 蛋白水平在 MPP⁺和 6-OHDA 处理的细胞中增加，但在鱼藤酮处理的细胞中没有变化，而内质网分子伴侣热休克蛋白 90kDaβ成员 1/葡萄糖调节蛋白 94（HSP90B1/GRP94）和 BiP 的蛋白水平在 MPP⁺和 6-OHDA 处理的细胞中分别上调。ERS 抑制剂 Salubrinal 显著降低了 MPP⁺和 6-OHDA 诱导的细胞死亡。此外，ERS 诱导剂--他普西龙和衣霉素降低了 RESP18 的表达，这与 BiP、GRP94 和 CHOP 的变化不同。用 Lenti-shRNA 沉默 RESP18 表达减轻了 MPP⁺诱导的细胞死亡，而过表达 RESP18 导致 MPP⁺和 6-OHDA 诱导的细胞死亡加重。总之，我们的结果表明 RESP18 参与了多巴胺能神经毒素的细胞毒性。
