Abstract
Insight into the normal function of PrPC, and how it can be subverted to produce neurotoxic effects, is provided by PrP molecules carrying deletions encompassing the conserved central region. The most neurotoxic of these mutants, Δ105–125 (called ΔCR), produces a spontaneous neurodegenerative illness when expressed in transgenic mice, and this phenotype can be dose-dependently suppressed by co-expression of wild-type PrP. Whether the toxic activity of ΔCR PrP and the protective activity or wild-type PrP are cell-autonomous, or can be exerted on neighboring cells, is unknown. To investigate this question, we have utilized co-cultures of differentiated neural stem cells derived from mice expressing ΔCR or wild-type PrP. Cells from the two kinds of mice, which are marked by the presence or absence of GFP, are differentiated together to yield neurons, astrocytes, and oligodendrocytes. As a surrogate read-out of ΔCR PrP toxicity, we assayed sensitivity of the cells to the cationic antibiotic, Zeocin. In a previous study, we reported that cells expressing ΔCR PrP are hypersensitive to the toxic effects of several cationic antibiotics, an effect that is suppressed by co-expression of wild type PrP, similar to the rescue of the neurodegenerative phenotype observed in transgenic mice. Using this system, we find that while ΔCR-dependent toxicity is cell-autonomous, the rescuing activity of wild-type PrP can be exerted in trans from nearby cells. These results provide important insights into how ΔCR PrP subverts a normal physiological function of PrPC, and the cellular mechanisms underlying the rescuing process.
Highlights
Prion diseases are fatal neurodegenerative disorders of humans and animals that are characterized by dementia, motor dysfunction, cerebral amyloidosis, and spongiform degeneration of the brain [1]
In the presence of epidermal growth factor (EGF), neural stem cells (NSCs) from all mouse lines formed spheroid bodies, measuring 50–200 mm in diameter, which could replicate in culture for multiple passages (Figure 1A and data not shown)
Expression of DCR PrP sensitizes several different cell lines to certain cationic antibiotics, including Zeocin, G418 and hygromicin, an effect that can be quantitated by the Drug-Based Cell Assay (DBCA) [16]
Summary
Prion diseases are fatal neurodegenerative disorders of humans and animals that are characterized by dementia, motor dysfunction, cerebral amyloidosis, and spongiform degeneration of the brain [1]. It is commonly accepted that PrPSc is a hallmark of prion diseases, emerging evidence suggests that its neurotoxicity relies on the presence of functional PrPC molecules at the cell surface [4] This conclusion is supported by the observation that the depletion of neuronal PrPC in mice with an established prion infection reversed both neuronal loss and the progression of clinical signs, despite the continuous production of PrPSc by surrounding glial cells [5,6]. This and other lines of evidence have sparked renewed efforts to understand the normal function of PrPC and how it may be hijacked to generate toxicity [7,8]. The physiological role of PrPC remains unclear, and far no robust assays have been developed for testing its function in vitro
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
