QPS Neuropharmacology offers several cellular models comprising primary neurons or transgenic and non-transgenic cell lines to mimic disease related conditions. Cellular models offer the advantage of a controlled environment useful for exploring single pathogenic mechanisms and the proteins involved. Our models are fast and cost-efficient. Customized models are generated gladly on request.
- Alpha-synuclein fibrils
- Okadaic acid
- NMDA lesion
- Glutamate lesion
- Sodium arsenite
- Sodium cyanide
- Growth factor withdrawal
Excitotoxicity is the pathological process by which neurons are damaged and killed by excessive stimulation by neurotransmitters such as glutamate. This occurs when receptors for the excitatory neurotransmitter glutamate (glutamate receptors) such as the NMDA receptor and AMPA receptor are overactivated by glutamatergic storm. Excitotoxins like NMDA which bind to these receptors, or pathologically high levels of glutamate, can cause excitotoxicity by allowing high levels of calcium ions to enter the cell.
Excitotoxicity may be involved in stroke or traumatic brain injury and in neurodegenerative diseases of the central nervous system such as multiple sclerosis, Alzheimer’s disease, amyotrophic lateral sclerosis (ALS), Parkinson’s disease, and also Huntington’s disease.
Stress granule formation
The RNA-binding protein TDP-43 is strongly linked to neurodegenerative diseases like ALS and FTLD. Several studies have shown that cytoplasmic TDP-43 aggregates co-localize with stress granule markers. Stress granules (SGs) are cytoplasmic inclusions that repress translation of a subset of RNAs during cellular stress. Since it was shown that SG formation contributes to accumulation of TDP-43, inhibition of SG formation and/or recruitment of TDP-43 to SGs are pathways that are currently in the focus of ALS research.
TDP-43 overexpressing neuroblastoma cells are treated with the well-described SG inducer sodium arsenite (SA). TDP-43 aggregation is measured in soluble and insoluble protein fractions via proteinsimple WES technology (Fig 1). Additionally, SG formation and TDP-43 recruitment can be analyzed by immunocytochemistry (Fig. 2). WES analysis shows a strong shift from soluble to insoluble TDP-43 species upon SA treatment (Fig. 1). Immunocytochemical staining for the SG marker G3BP reveals substantial SG formation in SA treated cells compared to the respective vehicle control (Fig. 2), while cycloheximide can counteract SG formation (Fig. 2 bottom row).
Figure 1. Effect of sodium arsenite (SA) treatment on soluble and insoluble TDP-43 levels. Cells were harvested after SA or vehicle treatment and a soluble and insoluble protein fraction were separated. Both fractions were analyzed for TDP-43 on proteinsimple WES. WES lane view of TDP-43 signal in soluble and insoluble fraction.
Figure 2. Representative images of vehicle (VC 0.1% DMSO), 200 µM sodium arsenite (SA) and SA lesioned plus 10 µM cycloheximide (CHX) treated SH-TDP-43 cells stained for the stress granule marker G3BP (orange) and human TDP-43 (green). Scale bar 100 µm.