Dataset Information

Low molecular weight species of TDP-43 generated by abnormal splicing form inclusions in amyotrophic lateral sclerosis and result in motor neuron death.

ABSTRACT: The presence of lower molecular weight species comprising the C-terminal region of TAR DNA-binding protein 43 (TDP-43) is a characteristic of TDP-43 proteinopathy in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Here, we have identified a novel splice variant of TDP-43 that is upregulated in ALS and generates a 35-kDa N-terminally truncated species through use of an alternate translation initiation codon (ATG(Met85)), denoted here as Met(85)-TDP-35. Met(85)-TDP-35 expressed ectopically in human neuroblastoma cells exhibited reduced solubility, cytoplasmic distribution, and aggregation. Furthermore, Met(85)-TDP-35 sequestered full-length TDP-43 from the nucleus to form cytoplasmic aggregates. Expression of Met(85)-TDP-35 in primary motor neurons resulted in the formation of Met(85)-TDP-35-positive cytoplasmic aggregates and motor neuron death. A neo-epitope antibody specific for Met(85)-TDP-35 labeled the 35-kDa lower molecular weight species on immunoblots of urea-soluble extracts from ALS-FTLD disease-affected tissues and co-labeled TDP-43-positive inclusions in ALS spinal cord sections, confirming the physiological relevance of this species. These results show that the 35-kDa low molecular weight species in ALS-FTLD can be generated from an abnormal splicing event and use of a downstream initiation codon and may represent a mechanism by which TDP-43 elicits its pathogenicity.

SUBMITTER: Xiao S

PROVIDER: S-EPMC4468798 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Low molecular weight species of TDP-43 generated by abnormal splicing form inclusions in amyotrophic lateral sclerosis and result in motor neuron death.

Xiao Shangxi S Sanelli Teresa T Chiang Helen H Sun Yulong Y Chakrabartty Avijit A Keith Julia J Rogaeva Ekaterina E Zinman Lorne L Robertson Janice J

Acta neuropathologica 20150319 1

The presence of lower molecular weight species comprising the C-terminal region of TAR DNA-binding protein 43 (TDP-43) is a characteristic of TDP-43 proteinopathy in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Here, we have identified a novel splice variant of TDP-43 that is upregulated in ALS and generates a 35-kDa N-terminally truncated species through use of an alternate translation initiation codon (ATG(Met85)), denoted here as Met(85)-TDP-35. Met(85)-TD ...[more]

PMID: 25788357

Similar Datasets

Project description:BackgroundThe brain predominantly expressed RING finger protein, Znf179, is known to be important for embryonic neuronal differentiation during brain development. Downregulation of Znf179 has been observed in motor neurons of adult mouse models for amyotrophic lateral sclerosis (ALS), yet the molecular function of Znf179 in neurodegeneration has never been previously described. Znf179 contains the classical C3HC4 RING finger domain, and numerous proteins containing C3HC4 RING finger domain act as E3 ubiquitin ligases. Hence, we are interested to identify whether Znf179 possesses E3 ligase activity and its role in ALS neuropathy.MethodsWe used in vivo and in vitro ubiquitination assay to examine the E3 ligase autoubiquitination activity of Znf179 and its effect on 26S proteasome activity. To search for the candidate substrates of Znf179, we immunoprecipitated Znf179 and subjected to mass spectrometry (MS) analysis to identify its interacting proteins. We found that ALS/ FTLD-U (frontotemporal lobar degeneration (FTLD) with ubiquitin inclusions)-related neurodegenerative TDP-43 protein is the E3 ligase substrate of Znf179. To further clarify the role of E3 ubiquitin ligase Znf179 in neurodegenerative TDP-43-UBI (ubiquitinated inclusions) (+) proteinopathy, the effect of Znf179-mediated TDP-43 polyubiquitination on TDP-43 protein stability, aggregate formation and nucleus/cytoplasm mislocalization were evaluated in vitro cell culture system and in vivo animal model.ResultsHere we report that Znf179 is a RING E3 ubiquitin ligase which possesses autoubiquitination feature and regulates 26S proteasome activity through modulating the protein expression levels of 19S/20S proteasome subunits. Our immunoprecipitation assay and MS analysis results revealed that the neuropathological TDP-43 protein is one of its E3 ligase substrate. Znf179 interactes with TDP-43 protein and mediates polyubiquitination of TDP-43 in vitro and in vivo. In neurodegenerative TDP-43 proteinopathy, we found that Znf179-mediated polyubiquitination of TDP-43 accelerates its protein turnover rate and attenuates insoluble pathologic TDP-43 aggregates, while knockout of Znf179 in mouse brain results in accumulation of insoluble TDP-43 and cytosolic TDP-43 inclusions in cortex, hippocampus and midbrain regions.ConclusionsHere we unveil the important role for the novel E3 ligase Znf179 in TDP-43-mediated neuropathy, and provide a potential therapeutic strategy for combating ALS/ FTLD-U neurodegenerative pathologies.

Project description:Hyperphosphorylated TDP-43 aggregates in the cytoplasm of motor neurons is a neuropathological signature of amyotrophic lateral sclerosis (ALS). These aggregates have been proposed to possess a toxic disease driving role in ALS pathogenesis and progression, however, the contribution of phosphorylation to TDP-43 aggregation and ALS disease mechanisms remains poorly understood. We've previously shown that CK1δ and CK1ε phosphorylate TDP-43 at disease relevant sites, and that genetic reduction and chemical inhibition could reduce phosphorylated TDP-43 (pTDP-43) levels in cellular models. In this study, we advanced our findings into the hTDP-43-ΔNLS in vivo mouse model of ALS and TDP-43 proteinopathy. This mouse model possesses robust disease-relevant features of ALS, including TDP-43 nuclear depletion, cytoplasmic pTDP-43 accumulation, motor behavior deficits, and shortened survival. We tested the effect of homozygous genetic deletion of Csnk1e in the hTDP-43-ΔNLS mouse model and observed a delay in the formation of pTDP-43 without significant ultimate rescue of TDP-43 proteinopathy or disease progression. Homozygous genetic deletion of Csnk1d is lethal in mice, and we were unable to test the role of CK1δ alone. We then targeted both CK1δ and CK1ε kinases by way of CK1δ/ε-selective PF-05236216 inhibitor in the hTDP-43-ΔNLS mouse model, reasoning that inhibiting CK1ε alone would be insufficient as shown by our Csnk1e knockout mouse model study. Treated mice demonstrated reduced TDP-43 phosphorylation, lowered Nf-L levels, and improved survival in the intermediate stages. The soluble TDP-43 may have been more amenable to the inhibitor treatment than insoluble TDP-43. However, the treatments did not result in improved functional measurements or in overall survival. Our results demonstrate that phosphorylation contributes to neuronal toxicity and suggest CK1δ/ε inhibition in combination with other therapies targeting TDP-43 pathology could potentially provide therapeutic benefit in ALS.

Dataset Information

Low molecular weight species of TDP-43 generated by abnormal splicing form inclusions in amyotrophic lateral sclerosis and result in motor neuron death.

Publications

Low molecular weight species of TDP-43 generated by abnormal splicing form inclusions in amyotrophic lateral sclerosis and result in motor neuron death.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets