Aberrant cleavage of TDP-43 enhances aggregation and cellular toxicity

作者：Yong‐Jie Zhang, Ya-Fei Xu, Casey Cook, Tania F. Gendron, Paul S. Roettges, Christopher D. Link, Wen-Lang Lin, Jimei Tong, Monica Castanedes‐Casey, Peter E.A. Ash, Jennifer Gass, Vijayaraghavan Rangachari, Emanuele Buratti, Francisco E. Baralle, Todd E. Golde, Dennis W. Dickson, Leonard Petrucelli · 发表于：Proceedings of the National Academy of Sciences · 年份：2009 · DOI：10.1073/pnas.0900688106 · 被引用次数：620 · 研究领域：Amyotrophic Lateral Sclerosis Research、Parkinson's Disease Mechanisms and Treatments、Neurogenetic and Muscular Disorders Research

Inclusions of TAR DNA-binding protein-43 (TDP-43), a nuclear protein that regulates transcription and RNA splicing, are the defining histopathological feature of frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-Us) and sporadic and familial forms of amyotrophic lateral sclerosis (ALS). In ALS and FTLD-U, aggregated, ubiquitinated, and N-terminally truncated TDP-43 can be isolated from brain tissue rich in neuronal and glial cytoplasmic inclusions. The loss of TDP-43 function resulting from inappropriate cleavage, translocation from the nucleus, or its sequestration into inclusions could play important roles in neurodegeneration. However, it is not known whether TDP-43 fragments directly mediate toxicity and, more specifically, whether their abnormal aggregation is a cause or consequence of pathogenesis. We report that the ectopic expression of a approximately 25-kDa TDP-43 fragment corresponding to the C-terminal truncation product of caspase-cleaved TDP-43 leads to the formation of toxic, insoluble, and ubiquitin- and phospho-positive cytoplasmic inclusions within cells. The 25-kDa C-terminal fragment is more prone to phosphorylation at S409/S410 than full-length TDP-43, but phosphorylation at these sites is not required for inclusion formation or toxicity. Although this fragment shows no biological activity, its exogenous expression neither inhibits the function nor causes the sequestration of full-length nuclear TDP-43, suggesting that the 25-kDa ...