Neuroprotective Function of Cellular Prion Protein in a Mouse Model of Amyotrophic Lateral Sclerosis

Department of Neurology, University of Ulm, Steinhovelstr.1, 89075 Ulm, Germany.
American Journal Of Pathology (Impact Factor: 4.59). 03/2010; 176(3):1409-20. DOI: 10.2353/ajpath.2010.090355
Source: PubMed


Transgenic mice expressing human mutated superoxide dismutase 1 (SOD1) linked to familial forms of amyotrophic lateral sclerosis are frequently used as a disease model. We used the SOD1G93A mouse in a cross-breeding strategy to study the function of physiological prion protein (Prp). SOD1G93APrp-/- mice exhibited a significantly reduced life span, and an earlier onset and accelerated progression of disease, as compared with SOD1G93APrp+/+ mice. Additionally, during disease progression, SOD1G93APrp-/- mice showed impaired rotarod performance, lower body weight, and reduced muscle strength. Histologically, SOD1G93APrp-/- mice showed reduced numbers of spinal cord motor neurons and extended areas occupied by large vacuoles early in the course of the disease. Analysis of spinal cord homogenates revealed no differences in SOD1 activity. Using an unbiased proteomic approach, a marked reduction of glial fibrillary acidic protein and enhanced levels of collapsing response mediator protein 2 and creatine kinase were detected in SOD1G93APrp-/- versus SOD1G93A mice. In the course of disease, Bcl-2 decreases, nuclear factor-kappaB increases, and Akt is activated, but these changes were largely unaffected by Prp expression. Exclusively in double-transgenic mice, we detected a significant increase in extracellular signal-regulated kinase 2 activation at clinical onset. We propose that Prp has a beneficial role in the SOD1G93A amyotrophic lateral sclerosis mouse model by influencing neuronal and/or glial factors involved in antioxidative defense, rather than anti-apoptotic signaling.

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Available from: Kerstin Elisabeth Braunstein, Apr 25, 2014
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    • "Mice at terminal disease stage were anesthetized and transcardially perfused with PBS for cryoconservation of the tissue or by PBS followed by paraformaldehyde in case of subsequent paraffin embedding as published elsewhere [16]. Prepared were the spinal cords as well as the whole brains separated sagittally into the two hemispheres. "
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    ABSTRACT: Objectives The paraffin-embedded tissue (PET) blot technique followed by limited protease digestion has been established to detect protein aggregates in prion diseases, alpha-synucleopathies, and tauopathies. We analyzed whether the scope of the method can be extended to analyze aggregates in mouse and human tissue with amyotrophic lateral sclerosis (ALS) associated with superoxide dismutase 1 (SOD1) mutation.Methods Formalin-fixed and paraffin-embedded brain and spinal cord tissue from SOD1G93A mice was first analyzed for the expression of SOD1, aggregated SOD1, ubiquitin, and p62 by convential immunohistochemistry and then used to establish the PET blot technique, limited protease digest, and immunodetection of SOD1 aggregates. The method was then transferred to spinal cord from an ALS patient with SOD1E100G mutation.ResultsMouse and human paraffin-embedded brain and spinal cord tissue can be blotted to membranes and stained with anti-SOD1 antibodies. The SOD1 labelling is abolished after limited proteolytic digest in controls, whereas under identical conditions SOD1 aggregates are detected the SOD1G93A mouse model of ALS and in human familial ALS. The most prominent areas where aggregates could be detected are the brainstem and the anterior horn of the spinal cord.DiscussionApplicability of the PET blot technique to demonstrate SOD1 aggregates in ALS tissue associated with mutations in the SOD1 gene offers a new approach to examine potential spreading of aggregates in the course of ALS.
    08/2014; 2(1):130. DOI:10.1186/PREACCEPT-8556289621364030
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    • "function inadvertently contributing to cellular decline. In a murine model of ALS, in which mice express a mutant form of SOD1 displaying a toxic gain of function, the absence of PrP leads to decreased levels of Bcl-2 and vacuolation of motor neurons (Steinacker et al., 2010). These observations might indicate that an overactivity of SOD1 caused by or coinciding with a disturbance of a PrP regulatory function could be responsible for characteristic prion pathology and cellular demise. "
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    ABSTRACT: Oxidative stress as a contributor to neuronal death during prion infection is supported by various oxidative damage markers accumulating in the brain during the course of disease. The cellular substrate of the causative agent, the prion protein, is also linked with protective functions against oxidative stress. Our previous work has found that in chronic prion infection an apoptotic sub-population of cells exhibit oxidative stress and accumulation of oxidised lipid and protein aggregates with caspase recruitment. Given the likely failure of antioxidant defence mechanisms within apoptotic prion-infected cells, we aimed to investigate the role of the critical antioxidant pathway components, superoxide dismutases (SOD) 1 and 2, in an in vitro model of chronic prion infection. Increased total SOD activity, attributable to SOD1, was found in the overall population coincident with a decrease in SOD2 protein levels. When apoptotic cells were separated from the total population, the induction of SOD activity in the infected apoptotic cells was lost with activity reduced back to levels seen in mock-infected control cells. In addition, mitochondrial superoxide production was increased and mitochondrial numbers decreased in the infected apoptotic sub-population. Further, a pan-caspase probe co-localised with SOD2 outside of mitochondria within cytosolic aggregates in infected cells and inhibition of caspase activity was able to restore cellular levels of SOD2 in the whole unseparated infected population to that of the mock-infected control cells. Our results suggest prion propagation exacerbates an apoptotic pathway whereby mitochondrial dysfunction follows mis-localisation of SOD2 to cytosolic caspases, permitting its degradation. Eventually cellular capacity to maintain oxidative homeostasis is overwhelmed, thus resulting in cell death.
    Disease Models and Mechanisms 04/2013; DOI:10.1242/dmm.010678 · 4.97 Impact Factor
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    ABSTRACT: The prion protein gene PRNP directs the synthesis of one of the most intensively studied mammalian proteins, the prion protein (PrP). Yet the physiological function of PrP has remained elusive and has created controversies in the literature. We found a downstream alternative translation initiation AUG codon surrounded by an optimal Kozak sequence in the +3 reading frame of PRNP. The corresponding alternative open reading frame encodes a polypeptide termed alternative prion protein (AltPrP) with a completely different amino acid sequence from PrP. We introduced a hemagglutinin (HA) tag in frame with AltPrP in PrP cDNAs from different species to test the expression of this novel polypeptide using anti-HA antibodies. AltPrP is constitutively coexpressed with human, bovine, sheep, and deer PrP. AltPrP is localized at the mitochondria and is up-regulated by endoplasmic reticulum stress and proteasomal inhibition. Generation of anti-AltPrP antibodies allowed us to test for endogenous expression of AltPrP in wild-type human cells expressing PrP. By transfecting cells with siRNA against PrP mRNA, we repressed expression of both PrP and AltPrP, confirming endogenous expression of AltPrP from PRNP. AltPrP was also detected in human brain homogenate, primary neurons, and peripheral blood mononuclear cells. These results demonstrate an unexpected function for PRNP, which, in addition to plasma membrane-anchored PrP, also encodes a second polypeptide termed AltPrP.
    The FASEB Journal 04/2011; 25(7):2373-86. DOI:10.1096/fj.10-173815 · 5.04 Impact Factor
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