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Expression of TDP-43 C-terminal fragments in vitro recapitulates pathological features of TDP-43 proteinopathies


Igaz, L M; Kwong, L K; Chen-Plotkin, A; Winton, M J; Unger, T L; Xu, Y; Neumann, M; Trojanowski, J Q; Lee, V M Y (2009). Expression of TDP-43 C-terminal fragments in vitro recapitulates pathological features of TDP-43 proteinopathies. Journal of Biological Chemistry, 284(13):8516-8524.

Abstract

The disease protein in frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U) and amyotrophic lateral sclerosis (ALS) was identified recently as the TDP-43 (TAR DNA-binding protein 43), thereby providing a molecular link between these two disorders. In FTLD-U and ALS, TDP-43 is redistributed from its normal nuclear localization to form cytoplasmic insoluble aggregates. Moreover, pathological TDP-43 is abnormally ubiquitinated, hyperphosphorylated, and N-terminally cleaved to generate C-terminal fragments (CTFs). However, the specific cleavage site(s) and the biochemical properties as well as the functional consequences of pathological TDP-43 CTFs remained unknown. Here we have identified the specific cleavage site, Arg(208), of a pathological TDP-43 CTF purified from FTLD-U brains and show that the expression of this and other TDP-43 CTFs in cultured cells recapitulates key features of TDP-43 proteinopathy. These include the formation of cytoplasmic aggregates that are ubiquitinated and abnormally phosphorylated at sites found in FTLD-U and ALS brain and spinal cord samples. Furthermore, we observed splicing abnormalities in a cell culture system expressing TDP-43 CTFs, and this is significant because the regulation of exon splicing is a known function of TDP-43. Thus, our results show that TDP-43 CTF expression recapitulates key biochemical features of pathological TDP-43 and support the hypothesis that the generation of TDP-43 CTFs is an important step in the pathogenesis of FTLD-U and ALS.

Abstract

The disease protein in frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U) and amyotrophic lateral sclerosis (ALS) was identified recently as the TDP-43 (TAR DNA-binding protein 43), thereby providing a molecular link between these two disorders. In FTLD-U and ALS, TDP-43 is redistributed from its normal nuclear localization to form cytoplasmic insoluble aggregates. Moreover, pathological TDP-43 is abnormally ubiquitinated, hyperphosphorylated, and N-terminally cleaved to generate C-terminal fragments (CTFs). However, the specific cleavage site(s) and the biochemical properties as well as the functional consequences of pathological TDP-43 CTFs remained unknown. Here we have identified the specific cleavage site, Arg(208), of a pathological TDP-43 CTF purified from FTLD-U brains and show that the expression of this and other TDP-43 CTFs in cultured cells recapitulates key features of TDP-43 proteinopathy. These include the formation of cytoplasmic aggregates that are ubiquitinated and abnormally phosphorylated at sites found in FTLD-U and ALS brain and spinal cord samples. Furthermore, we observed splicing abnormalities in a cell culture system expressing TDP-43 CTFs, and this is significant because the regulation of exon splicing is a known function of TDP-43. Thus, our results show that TDP-43 CTF expression recapitulates key biochemical features of pathological TDP-43 and support the hypothesis that the generation of TDP-43 CTFs is an important step in the pathogenesis of FTLD-U and ALS.

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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Institute of Neuropathology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2009
Deposited On:29 Jan 2010 12:02
Last Modified:23 Sep 2018 05:12
Publisher:American Society for Biochemistry and Molecular Biology
ISSN:0021-9258
Additional Information:This research was originally published in Igaz, L M; Kwong, L K; Chen-Plotkin, A; Winton, M J; Unger, T L; Xu, Y; Neumann, M; Trojanowski, J Q; Lee, V M Y (2009). Expression of TDP-43 C-terminal fragments in vitro recapitulates pathological features of TDP-43 proteinopathies. Journal of Biological Chemistry, 284(13):8516-8524. © the American Society for Biochemistry and Molecular Biology
OA Status:Hybrid
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1074/jbc.M809462200
PubMed ID:19164285

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