Mitochondria, ER, and nuclear membrane defects reveal early mechanisms for upper motor neuron vulnerability with respect to TDP-43 pathology

Gautam, Mukesh; Jara, Javier H.; Koçak, Nuran; Rylaarsdam, Lauren; Kim, Ki Dong; Bigio, Eileen H.; Özdinler, P. Hande

doi:10.1007/s00401-018-1934-8

Cited by 64 publications

(138 citation statements)

References 78 publications

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“…Despite our data, impaired mitochondrial function was shown to be closely related to ALS pathophysiology (Muyderman and Chen, 2014). Mitochondrial dysfunction is another toxic effect mediated by TDP-43 according to independent reports [23,24], and TDP-43 colocalization in the mitochondria seems to be essential for this deleterious effect [25,26].…”

Section: Tdp-43 Overexpression and Mitochondrial Functionmentioning

confidence: 92%

TDP-43-Mediated Toxicity in HEK293T Cells: A Fast and Reproducible Protocol To Be Employed in the Search of New Therapeutic Options against Amyotrophic Lateral Sclerosis

Lanznaster

Bourgeais

Bruno

et al. 2019

Cells

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Cytoplasmic TDP-43 aggregates are a hallmark of amyotrophic lateral sclerosis (ALS). Today, only two drugs are available for ALS treatment, and their modest effect prompts researchers to search for new therapeutic options. TDP-43 represents one of the most promising targets for therapeutic intervention, but reliable and reproducible in vitro protocols for TDP-43-mediated toxicity are lacking. Here, we used HEK293T cells transfected with increasing concentrations of TDP-43-expressing plasmid to evaluate different parameters of toxicity and alterations in cellular metabolism. Overexpression of TDP-43 induced aggregates occurrence followed by the detection of 25-and 35-kDa forms of TDP-43. TDP-43 overexpression decreased cell viability and increased cells arrested at G2/M phase and nuclear fragmentation. Analysis of the energetic metabolism showed a tendency to decrease oxidative phosphorylation and increase glycolysis, but no statistical differences were observed. Metabolomics revealed alterations in different metabolites (mainly sphingolipids and glycerophospholipids) in cells overexpressing TDP-43. Our data reveal the main role of TDP-43 aggregation in cellular death and highlight novel insight into the mechanism of cellular toxicity induced by TDP-43. Here, we provide a simple, sensitive, and reliable protocol in a human-derived cell line to be used in high-throughput screenings of potential therapeutic molecules for ALS treatment.

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Section: Tdp-43 Overexpression and Mitochondrial Functionmentioning

confidence: 92%

TDP-43-Mediated Toxicity in HEK293T Cells: A Fast and Reproducible Protocol To Be Employed in the Search of New Therapeutic Options against Amyotrophic Lateral Sclerosis

Lanznaster

Bourgeais

Bruno

et al. 2019

Cells

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“…In fact, moderate over expression of the TDP-43 has been reported to cause mitochondrial aggregation and also enhance the levels of mitochondrial fission protein Fis1 [29]. Consistent reports from several model systems, including the ALS patient-derived fibroblasts harbouring TDP-43 mutation, have also indicated of the damage to the mitochondria upon the TDP-43 expression [18,[30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 76%

Role ofCNC1gene in TDP-43 aggregation-induced oxidative stress-mediated cell death inS. cerevisiaemodel of ALS

Bharathi

Girdhar

Patel

2020

Preprint

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TDP-43 is a multi-functional ribonucleoprotein that is also found deposited as hyperphosphorylated and ubiquitinated TDP-43 inclusions in the brain and spinal cord of the patients of the motor neuron diseases, amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Till date, how the cell death ensues is not fully deciphered although several molecular mechanisms of the TDP-43 toxicity such as impairments of endocytosis and chromatin remodelling, mis-regulations of autophagy and proteasome function, mis-localization to the mitochondria and generation of oxidative stress etc., have been proposed. A predominantly nuclear protein, Cyclin C, can regulate the oxidative stress response by affecting the transcription of stress response genes and also by translocation to the cytoplasm for the activation of the mitochondrial fragmentation-dependent cell death pathway. Using the well-established yeast model of TDP-43 aggregation and toxicity, we examined here whether upon TDP-43 aggregation, the cell survival depends on the presence of the CNC1 gene that encodes Cyclin C protein or other genes that encode proteins that function in conjunction with Cyclin C, such as the DNM1, FIS1 and MED13 genes. We found that the TDP-43 toxicity is significantly reduced in the yeast deleted for the CNC1 or DNM1 genes. Importantly, the rescue of TDP-43 toxicity in these yeast deletion backgrounds required the presence of functional mitochondria. Also, the deletion of YBH3 gene, which encodes for a protein involved in the mitochondria-dependent apoptosis, also reduced the TDP-43 toxicity. Furthermore, Cyclin C-YFP was observed to localize from the nucleus to the cytoplasm in response to the TDP-43 co-expression. Also, this cytoplasmic localization of Cyclin C was prevented by the addition of an anti-oxidant molecule, N-acetyl-cysteine.Taken together, our data suggest that Cyclin C, Dnm1 and Ybh3 proteins are important in mediating the TDP-43-induced oxidative stress-mediated cell death in the S. cerevisiae model.3

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“…Interestingly, in the spinal cord, not all SMN display equal vulnerability and some remain resistant to degeneration. There appears to be a progressive line of degeneration among different subsets of SMN, where S alpha SMN displays initial signs of degeneration, followed by FR and FF remain mostly resistant [20,[28][29][30][31][32]. Differentiating vulnerable and degeneration-resistant neurons in a reporter line is of great importance to monitor and assess their responses to compound treatment strategies.…”

Section: Discussionmentioning

confidence: 99%

The Timing and Extent of Motor Neuron Vulnerability in ALS Correlates with Accumulation of Misfolded SOD1 Protein in the Cortex and in the Spinal Cord

Genç¹,

Gozutok²,

Koçak³

et al. 2020

Cells

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Understanding the cellular and molecular basis of selective vulnerability has been challenging, especially for motor neuron diseases. Developing drugs that improve the health of neurons that display selective vulnerability relies on in vivo cell-based models and quantitative readout measures that translate to patient outcome. We initially developed and characterized UCHL1-eGFP mice, in which motor neurons are labeled with eGFP that is stable and long-lasting. By crossing UCHL1-eGFP to amyotrophic lateral sclerosis (ALS) disease models, we generated ALS mouse models with fluorescently labeled motor neurons. Their examination over time began to reveal the cellular basis of selective vulnerability even within the related motor neuron pools. Accumulation of misfolded SOD1 protein both in the corticospinal and spinal motor neurons over time correlated with the timing and extent of degeneration. This further proved simultaneous degeneration of both upper and lower motor neurons, and the requirement to consider both upper and lower motor neuron populations in drug discovery efforts. Demonstration of the direct correlation between misfolded SOD1 accumulation and motor neuron degeneration in both cortex and spinal cord is important for building cell-based assays in vivo. Our report sets the stage for shifting focus from mice to diseased neurons for drug discovery efforts, especially for motor neuron diseases.

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Mitochondria, ER, and nuclear membrane defects reveal early mechanisms for upper motor neuron vulnerability with respect to TDP-43 pathology

Cited by 64 publications

References 78 publications

TDP-43-Mediated Toxicity in HEK293T Cells: A Fast and Reproducible Protocol To Be Employed in the Search of New Therapeutic Options against Amyotrophic Lateral Sclerosis

TDP-43-Mediated Toxicity in HEK293T Cells: A Fast and Reproducible Protocol To Be Employed in the Search of New Therapeutic Options against Amyotrophic Lateral Sclerosis

Role ofCNC1gene in TDP-43 aggregation-induced oxidative stress-mediated cell death inS. cerevisiaemodel of ALS

The Timing and Extent of Motor Neuron Vulnerability in ALS Correlates with Accumulation of Misfolded SOD1 Protein in the Cortex and in the Spinal Cord

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