Distinct pathways leading to TDP-43-induced cellular dysfunctions.
Distinct pathways leading to TDP-43-induced cellular dysfunctions.
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DOI：
10.1093/hmg/ddu152
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发表时间：
2014-08
影响因子：
3.5
通讯作者：
M. Yamashita;T. Nonaka;S. Hirai;A. Miwa;H. Okado;T. Arai;M. Hosokawa;H. Akiyama;M. Hasegawa
中科院分区：
文献类型：
--
作者：
M. Yamashita;T. Nonaka;S. Hirai;A. Miwa;H. Okado;T. Arai;M. Hosokawa;H. Akiyama;M. Hasegawa
TAR DNA结合蛋白（TDP-43）是肌萎缩侧索硬化症（ALS）和额颞叶变性（FTLD-TDP）患者脑内包涵体的主要成分蛋白。然而，TDP-43引起神经元功能障碍和死亡的分子机制仍然未知。在这里，我们报告了全长TDP-43（FL-TDP）及其C-末端片段（CTF）在SH-SY 5 Y细胞中的不同细胞毒性作用。当使用慢病毒系统在细胞中过表达FL-TDP时，外源性TDP-43与内源性TDP-43一样，主要在细胞核中表达而没有任何细胞内包涵体。然而，这些细胞显示出显著的细胞死亡、半胱天冬酶激活和G2/M期生长停滞，表明即使是简单的TDP-43过表达也会诱导细胞功能障碍，导致凋亡。另一方面，与表达FL-TDP的细胞相比，表达TDP-43 CTF的细胞显示细胞质聚集体，但没有显著的细胞死亡。共聚焦显微镜分析显示，RNA聚合酶II（RNA pol II）和几个转录因子，如特异性蛋白1和cAMP反应元件结合蛋白，与TDP-43 CTF的聚集体共定位，表明这些因子螯合到TDP-43聚集体引起转录失调。事实上，在FTLD-TDP患者的脑中检测到TDP-43包涵体处的RNA pol II积累。此外，在含有磷酸化和聚集的TDP-43病理的FTLD-TDP脑的受影响神经元中未观察到细胞凋亡。我们的研究结果表明，TDP-43诱导的细胞功能障碍的不同途径可能有助于参与ALS和FTLD-TDP发病的退化级联反应。
TAR DNA-binding protein of 43 kDa (TDP-43) is the major component protein of inclusions found in brains of patients with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD-TDP). However, the molecular mechanisms by which TDP-43 causes neuronal dysfunction and death remain unknown. Here, we report distinct cytotoxic effects of full-length TDP-43 (FL-TDP) and its C-terminal fragment (CTF) in SH-SY5Y cells. When FL-TDP was overexpressed in the cells using a lentiviral system, exogenous TDP-43, like endogenous TDP-43, was expressed mainly in nuclei of cells without any intracellular inclusions. However, these cells showed striking cell death, caspase activation and growth arrest at G2/M phase, indicating that even simple overexpression of TDP-43 induces cellular dysfunctions leading to apoptosis. On the other hand, cells expressing TDP-43 CTF showed cytoplasmic aggregates but without significant cell death, compared with cells expressing FL-TDP. Confocal microscopic analyses revealed that RNA polymerase II (RNA pol II) and several transcription factors, such as specificity protein 1 and cAMP-response-element-binding protein, were co-localized with the aggregates of TDP-43 CTF, suggesting that sequestration of these factors into TDP-43 aggregates caused transcriptional dysregulation. Indeed, accumulation of RNA pol II at TDP-43 inclusions was detected in brains of patients with FTLD-TDP. Furthermore, apoptosis was not observed in affected neurons of FTLD-TDP brains containing phosphorylated and aggregated TDP-43 pathology. Our results suggest that different pathways of TDP-43-induced cellular dysfunction may contribute to the degeneration cascades involved in the onset of ALS and FTLD-TDP.