Dysregulation of the ALS-associated gene TDP-43 leads to neuronal death and degeneration in mice.

ABSTRACT: Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are characterized by cytoplasmic protein aggregates in the brain and spinal cord that include TAR-DNA binding protein 43 (TDP-43). TDP-43 is normally localized in the nucleus with roles in the regulation of gene expression, and pathological cytoplasmic aggregates are associated with depletion of nuclear protein. Here, we generated transgenic mice expressing human TDP-43 with a defective nuclear localization signal in the forebrain (hTDP-43-?NLS), and compared them with mice expressing WT hTDP-43 (hTDP-43-WT) to determine the effects of mislocalized cytoplasmic TDP-43 on neuronal viability. Expression of either hTDP-43-?NLS or hTDP-43-WT led to neuron loss in selectively vulnerable forebrain regions, corticospinal tract degeneration, and motor spasticity recapitulating key aspects of FTLD and primary lateral sclerosis. Only rare cytoplasmic phosphorylated and ubiquitinated TDP-43 inclusions were seen in hTDP-43-?NLS mice, suggesting that cytoplasmic inclusions were not required to induce neuronal death. Instead, neurodegeneration in hTDP-43 and hTDP-43-?NLS-expressing neurons was accompanied by a dramatic downregulation of the endogenous mouse TDP-43. Moreover, mice expressing hTDP-43-?NLS exhibited profound changes in gene expression in cortical neurons. Our data suggest that perturbation of endogenous nuclear TDP-43 results in loss of normal TDP-43 function(s) and gene regulatory pathways, culminating in degeneration of selectively vulnerable affected neurons.

SUBMITTER: Igaz LM 

PROVIDER: S-EPMC3026736 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature