Among known ALS genes, TDP-43 is of particular interest because its protein is hyper-phosphorylated and ubiquitinated in sporadic ALS. Compared with genetic mutation, post-translational modification is difficult to detect in patients and hard to reproduce in animal models. Therefore, a critical step toward understanding TDP-43 pathogenesis is revealing the pathways by which mutant TDP-43 causes neurodegeneration in ALS. TDP-43 binds to many RNAs and proteins, but how pathogenic mutation impacts TDP-43 function has not yet been determined, particularly in an appropriate animal model. Unexpectedly, overexpression of both WT and mutant TDP-43 in rodents causes indistinguishable phenotypes, indicating that excessive TDP-43 is neurotoxic. Because transgene expression is heavily influenced by position effect, the patterns and levels of transgene expression vary greatly from line to line. Whether mutant TDP-43 is more or less toxic than its WT form thus cannot be determined using existing transgenic models. The question regarding the impact of pathogenic mutation on TDP-43 function is further confounded by observations that TDP-43 depletion induces neurodegeneration in TDP-43 knock-out and knock-down mice. As TDP-43 binds to the 3'-untranslated region of its own mRNA and thereby regulates its own expression, the cDNA knock-in (KI) approach destroys TDP-43 self-regulatory machinery, rendering TDP-43 KI animals not very useful. Even 7 years after the discovery of TDP-43 mutation in ALS, whether mutant TDP-43 causes ALS through a gain or loss of function is still uncertain, and this unresolved issue is a roadblock to unraveling TDP-43 disease mechanisms. To resolve this critical issue, we created KI rats by introducing a single disease-linked point mutation into the rat genome. With the unprecedented rat models, we will determine how pathogenic mutation impacts TDP-43 function in a systematic manner.

Public Health Relevance

Using novel knockin rats, this proposal will examine how pathogenic mutation of TDP-43 affects its function in a systematic manner, providing a critical insight into the mechanisms of amyotrophic lateral sclerosis caused by TDP-43 mutation.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Cell Death in Neurodegeneration Study Section (CDIN)
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Gubitz, Amelie
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University of Central Florida
Other Basic Sciences
Schools of Medicine
United States
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Huang, Bo; Wu, Qinxue; Zhou, Hongxia et al. (2016) Increased Ubqln2 expression causes neuron death in transgenic rats. J Neurochem 139:285-293
Wu, Qinxue; Liu, Mujun; Huang, Cao et al. (2015) Pathogenic Ubqln2 gains toxic properties to induce neuron death. Acta Neuropathol 129:417-28
Huang, Cao; Huang, Bo; Bi, Fangfang et al. (2014) Profiling the genes affected by pathogenic TDP-43 in astrocytes. J Neurochem 129:932-9
Bi, Fangfang; Li, Fang; Huang, Cao et al. (2013) Pathogenic mutation in VPS35 impairs its protection against MPP(+) cytotoxicity. Int J Biol Sci 9:149-55
Bi, Fangfang; Huang, Cao; Tong, Jianbin et al. (2013) Reactive astrocytes secrete lcn2 to promote neuron death. Proc Natl Acad Sci U S A 110:4069-74
Tong, Jianbin; Huang, Cao; Bi, Fangfang et al. (2013) Expression of ALS-linked TDP-43 mutant in astrocytes causes non-cell-autonomous motor neuron death in rats. EMBO J 32:1917-26
Huang, Cao; Tong, Jianbin; Bi, Fangfang et al. (2012) Entorhinal cortical neurons are the primary targets of FUS mislocalization and ubiquitin aggregation in FUS transgenic rats. Hum Mol Genet 21:4602-14
Tong, Jianbin; Huang, Cao; Bi, Fangfang et al. (2012) XBP1 depletion precedes ubiquitin aggregation and Golgi fragmentation in TDP-43 transgenic rats. J Neurochem 123:406-16
Huang, Cao; Tong, Jianbin; Bi, Fangfang et al. (2012) Mutant TDP-43 in motor neurons promotes the onset and progression of ALS in rats. J Clin Invest 122:107-18