Neurotoxic effects of TDP-43 overexpression in C. elegans.
RNA-binding protein TDP-43 has been associated with multiple neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal lobar dementia. We have engineered pan-neuronal expression of human TDP-43 protein in Caenorhabditis elegans, with the goal of generating a convenient in vivo model of TDP-43 function and neurotoxicity. Transgenic worms with the neuronal expression of human TDP-43 exhibit an 'uncoordinated' phenotype and have abnormal motorneuron synapses. Caenorhabditis elegans contains a single putative ortholog of TDP-43, designated TDP-1, which we show can support alternative splicing of CFTR in a cell-based assay. Neuronal overexpression of TDP-1 also results in an uncoordinated phenotype, while genetic deletion of the tdp-1 gene does not affect movement or alter motorneuron synapses. By using the uncoordinated phenotype as a read-out of TDP-43 overexpression neurotoxicty, we have investigated the contribution of specific TDP-43 domains and subcellular localization to toxicity. Full-length (wild-type) human TDP-43 expressed in C. elegans is localized to the nucleus. Deletion of either RNA recognition domain (RRM1 or RRM2) completely blocks neurotoxicity, as does deletion of the C-terminal region. These deleted TDP-43 variants still accumulate in the nucleus, although their subnuclear distribution is altered. Interestingly, fusion of TDP-1 C-terminal sequences to TDP-43 missing its C-terminal domain restores normal subnuclear localization and toxicity in C. elegans and CFTR splicing in cell-based assays. Overexpression of wild-type, full-length TDP-43 in mammalian cells (differentiated M17 cells) can also result in cell toxicity. Our results demonstrate that in vivo TDP-43 neurotoxicity can result from nuclear activity of overexpressed full-length protein.
Ash
Peter E A
PE
Department of Neuroscience, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
Zhang
Yong-Jie
YJ
Roberts
Christine M
CM
Saldi
Tassa
T
Hutter
Harald
H
Buratti
Emanuele
E
Petrucelli
Leonard
L
Link
Christopher D
CD
D000818:Animals; D030801:Animals, Genetically Modified; D015153:Blotting, Western; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D010641:Phenotype; D017384:Sequence Deletion; D013569:Synapses / Q000378:metabolism* / Q000473:pathology; D014162:Transfection
D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D049452:Green Fluorescent Proteins