Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, UK.
Geoffrey Jefferson Brain Research Centre, The Manchester Academic Health Science Centre, Northern Care Alliance NHS Group, University of Manchester, Manchester, UK.
Sci Rep. 2022 Mar 21;12(1):4799. doi: 10.1038/s41598-022-08724-w.
A repeat expansion in C9orf72 is the major cause of both frontotemporal dementia and amyotrophic lateral sclerosis, accounting for approximately 1 in 12 cases of either disease. The expansion is translated to produce five dipeptide repeat proteins (DPRs) which aggregate in patient brain and are toxic in numerous models, though the mechanisms underlying this toxicity are poorly understood. Recent studies highlight nucleocytoplasmic transport impairments as a potential mechanism underlying neurodegeneration in C9orf72-linked disease, although the contribution of DPRs to this remains unclear. We expressed DPRs in HeLa cells, in the absence of repeat RNA. Crucially, we expressed DPRs at repeat-lengths found in patients (> 1000 units), ensuring our findings were relevant to disease. Immunofluorescence imaging was used to investigate the impact of each DPR on the nucleus, nucleocytoplasmic transport machinery and TDP-43 localisation. DPRs impaired the structural integrity of the nucleus, causing nuclear membrane disruption and misshapen nuclei. Ran and RanGAP, two proteins required for nucleocytoplasmic transport, were also mislocalised in DPR-expressing cells. Furthermore, DPRs triggered mislocalisation of TDP-43 to the cytoplasm, and this occurred in the same cells as Ran and RanGAP mislocalisation, suggesting a potential link between DPRs, nucleocytoplasmic transport impairments and TDP-43 pathology.
C9orf72 中的重复扩展是额颞叶痴呆和肌萎缩侧索硬化症的主要原因，约占这两种疾病的 1/12。该扩展被翻译产生了五种二肽重复蛋白（DPRs），这些蛋白在患者大脑中聚集并在许多模型中具有毒性，尽管其毒性的机制仍不清楚。最近的研究强调核质转运受损是 C9orf72 相关疾病神经退行性变的潜在机制，尽管 DPRs 对此的贡献尚不清楚。我们在 HeLa 细胞中表达了 DPRs，而没有重复 RNA。至关重要的是，我们在患者中发现的重复长度（>1000 个单位）表达了 DPRs，确保了我们的发现与疾病相关。免疫荧光成像用于研究每种 DPR 对核、核质转运机制和 TDP-43 定位的影响。DPRs 破坏了核的结构完整性，导致核膜破裂和核形状异常。Ran 和 RanGAP 是核质转运所必需的两种蛋白质，在表达 DPR 的细胞中也发生了定位错误。此外，DPRs 触发了 TDP-43 向细胞质的错误定位，并且这种情况发生在 Ran 和 RanGAP 定位错误的相同细胞中，这表明 DPRs、核质转运受损和 TDP-43 病理学之间存在潜在联系。
