Characterization of alternative isoforms and inclusion body of the TAR DNA-binding protein-43

Yoshinori Nishimoto, Daisuke Ito, Takuya Yagi, Yoshihiro Nihei, Yoshiko Tsunodo, Norihiro Suzuki

研究成果: Article査読

108 被引用数 (Scopus)

抄録

TAR DNA-binding protein-43 (TDP-43) has been recently identified as a major component of the ubiquitinated inclusions found in frontotemporal lobar degeneration with ubiquitin-positive inclusions and in amyotrophic lateral sclerosis, diseases that are collectively termed TDP-43 proteinopathies. Several amyotrophic lateral sclerosis-linked mutations of the TDP-43 gene have also been identified; however, the precise molecular mechanisms underlying the neurodegeneration remain unclear. To investigate the biochemical characteristics of TDP-43, we examined truncation, isoforms, and cytoplasmic inclusion (foci) formation using TDP-43-expressing cells. Under apoptosis, caspase-3 generates two 35-kDa (p35f) and 25-kDa (p25f) fragments. However, in caspase-3(-/-) cells, novel caspase-3-independent isoforms of these two variants (p35iso and p25iso) were also detected under normal conditions. With a deletion mutant series, the critical domains for generating both isoforms were determined and applied to in vitro transcription/translation, revealing alternate in-frame translation start sites downstream of the natural initiation codon. Subcellular localization analysis indicated that p35 (p35f and p35iso) expression leads to the formation of stress granules, cellular structures that package mRNA and RNA-binding proteins during cell stress. After applying proteasome inhibitors, aggresomes, which are aggregates of misfolded proteins, were formed in the cytoplasm of cells expressing p35. Collectively, this study demonstrates that the 35-kDa isoforms of TDP-43 assemble in stress granules, suggesting that TDP-43 plays an important role in translation, stability, and metabolism of mRNA. Our findings provide new biological and pathological insight into the development of TDP-43 proteinopathies.

本文言語English
ページ(範囲)608-619
ページ数12
ジャーナルJournal of Biological Chemistry
285
1
DOI
出版ステータスPublished - 2010 1月 1

ASJC Scopus subject areas

  • 生化学
  • 分子生物学
  • 細胞生物学

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