Expression of mutant TDP-43 induces neuronal dysfunction in transgenic mice

Ya Fei Xu, Yong Jie Zhang, Wen Lang Lin, Xiangkun Cao, Caroline Stetler, Dennis W. Dickson, Jada Lewis, Leonard Petrucelli

Research output: Contribution to journalArticle

93 Scopus citations

Abstract

Background: Abnormal distribution, modification and aggregation of transactivation response DNA-binding protein 43 (TDP-43) are the hallmarks of multiple neurodegenerative diseases, especially frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U) and amyotrophic lateral sclerosis (ALS). Researchers have identified 44 mutations in the TARDBP gene that encode TDP-43 as causative for cases of sporadic and familial ALS http://www.molgen.ua.ac.be/FTDMutations/. Certain mutant forms of TDP-43, such as M337V, are associated with increased low molecular weight (LMW) fragments compared to wild-type (WT) TDP-43 and cause neuronal apoptosis and developmental delay in chick embryos. Such findings support a direct link between altered TDP-43 function and neurodegeneration. Results: To explore the pathogenic properties of the M337V mutation, we generated and characterized two mouse lines expressing human TDP-43 (hTDP-43 M337V) carrying this mutation. hTDP-43 M337Vwas expressed primarily in the nuclei of neurons in the brain and spinal cord, and intranuclear and cytoplasmic phosphorylated TDP-43 aggregates were frequently detected. The levels of TDP-43 LMW products of ∼25 kDa and ∼35 kDa species were also increased in the transgenic mice. Moreover, overexpression of hTDP-43 M337Vdramatically down regulated the levels of mouse TDP-43 (mTDP-43) protein and RNA, indicating TDP-43 levels are tightly controlled in mammalian systems. TDP-43 M337Vmice displayed reactive gliosis, widespread ubiquitination, chromatolysis, gait abnormalities, and early lethality. Abnormal cytoplasmic mitochondrial aggregates and abnormal phosphorylated tau were also detected in the mice. Conclusion: Our novel TDP-43 M337Vmouse model indicates that overexpression of hTDP-43 M337Valone is toxic in vivo. Because overexpression of hTDP-43 in wild-type TDP-43 and TDP-43 M337Vmouse models produces similar phenotypes, the mechanisms causing pathogenesis in the mutant model remain unknown. However, our results suggest that overexpression of the hTDP-43 M337Vcan cause neuronal dysfunction due to its effect on a number of cell organelles and proteins, such as mitochondria and TDP-43, that are critical for neuronal activity. The mutant model will serve as a valuable tool in the development of future studies designed to uncover pathways associated with TDP-43 neurotoxicity and the precise roles TDP-43 RNA targets play in neurodegeneration.

Original languageEnglish (US)
Article number73
JournalMolecular neurodegeneration
Volume6
Issue number1
DOIs
StatePublished - Nov 21 2011

Keywords

  • ALS
  • aggregation
  • mitochondria
  • mouse model
  • tau

ASJC Scopus subject areas

  • Molecular Biology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience

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