The Link of the Prion Protein with Ca Metabolism and ROS Production, and the Possible Implication in Aβ Toxicity.

The cellular prion protein (PrP) is an ubiquitous cell surface protein mostly expressed in neurons, where it localizes to both pre- and post-synaptic membranes. PrP aberrant conformers are the major components of mammalian prions, the infectious agents responsible for incurable neurodegenerative disorders. PrP was also proposed to bind aggregated misfolded proteins/peptides, and to mediate their neurotoxic signal.

The Prion Protein Regulates Synaptic Transmission by Controlling the Expression of Proteins Key to Synaptic Vesicle Recycling and Exocytosis.

The cellular prion protein (PrP), whose misfolded conformers are implicated in prion diseases, localizes to both the presynaptic membrane and postsynaptic density. To explore possible molecular contributions of PrP to synaptic transmission, we utilized a mass spectrometry approach to quantify the release of glutamate from primary cerebellar granule neurons (CGN) expressing, or deprived of (PrP-KO), PrP, following a depolarizing stimulus. Under the same conditions, we also tracked recycling of synaptic vesicles (SVs) in the two neuronal populations.

Generation and validation of novel adeno-associated viral vectors for the analysis of Ca homeostasis in motor neurons.

A finely tuned Ca homeostasis in restricted cell domains is of fundamental importance for neurons, where transient Ca oscillations direct the proper coordination of electro-chemical signals and overall neuronal metabolism. Once such a precise regulation is unbalanced, however, neuronal functions and viability are severely compromised. Accordingly, disturbed Ca metabolism has often been claimed as a major contributor to different neurodegenerative disorders, such as amyotrophic lateral sclerosis that is characterised by selective motor neuron (MN) damage.

The prion protein regulates glutamate-mediated Ca entry and mitochondrial Ca accumulation in neurons.

The cellular prion protein (PrP) whose conformational misfolding leads to the production of deadly prions, has a still-unclarified cellular function despite decades of intensive research. Following our recent finding that PrP limits Ca entry via store-operated Ca channels in neurons, we investigated whether the protein could also control the activity of ionotropic glutamate receptors (iGluRs). To this end, we compared local Ca movements in primary cerebellar granule neurons and cortical neurons transduced with genetically encoded Ca probes and expressing, or not expressing, PrP Our investigation demonstrated that PrP downregulates Ca entry through each specific agonist-stimulated iGluR and after stimulation by glutamate.

Absolute quantification of myosin heavy chain isoforms by selected reaction monitoring can underscore skeletal muscle changes in a mouse model of amyotrophic lateral sclerosis.

Skeletal muscle fibers contain different isoforms of myosin heavy chain (MyHC) that define distinctive contractile properties. In light of the muscle capacity to adapt MyHC expression to pathophysiological conditions, a rapid and quantitative assessment of MyHC isoforms in small muscle tissue quantities would represent a valuable diagnostic tool for (neuro)muscular diseases. As past protocols did not meet these requirements, in the present study we applied a targeted proteomic approach based on selected reaction monitoring that allowed the absolute quantification of slow and fast MyHC isoforms in different mouse skeletal muscles with high reproducibility.

Age-dependent neuromuscular impairment in prion protein knockout mice.

Introduction: The cellular prion protein (PrP(C) ) is commonly recognized as the precursor of prions, the infectious agents of the fatal transmissible spongiform encephalopathies, or prion diseases. Despite extensive effort, the physiological role of PrP(C) is still ambiguous. Evidence has suggested that PrP(C) is involved in different cellular functions, including peripheral nerve integrity and skeletal muscle physiology.

Prions and prion-like pathogens in neurodegenerative disorders.

Prions are unique elements in biology, being able to transmit biological information from one organism to another in the absence of nucleic acids. They have been identified as self-replicating proteinaceous agents responsible for the onset of rare and fatal neurodegenerative disorders-known as transmissible spongiform encephalopathies, or prion diseases-which affect humans and other animal species. More recently, it has been proposed that other proteins associated with common neurodegenerative disorders, such as Alzheimer's and Parkinson's disease, can self-replicate like prions, thus sustaining the spread of neurotoxic entities throughout the nervous system.

The cellular prion protein counteracts cardiac oxidative stress.

Aims: The cellular prion protein, PrP(C), whose aberrant isoforms are related to prion diseases of humans and animals, has a still obscure physiological function. Having observed an increased expression of PrP(C) in two in vivo paradigms of heart remodelling, we focused on isolated mouse hearts to ascertain the capacity of PrP(C) to antagonize oxidative damage induced by ischaemic and non-ischaemic protocols.

Methods And Results: Hearts isolated from mice expressing PrP(C) in variable amounts were subjected to different and complementary oxidative perfusion protocols.

Altered behavioral aspects of aged mice lacking the cellular prion protein.

The biological function of the prion protein, which is intimately involved in the onset of prion diseases, remains unclear. To understand whether the prion protein could play a role in animal behavior, a battery of tests was applied to young and aged mice that express, or not, the prion protein. In contrast to the similar results obtained in all young animals, we found that aged mice lacking the prion protein reacted to new and stressful environments differently than their wild-type counterparts.

Relative quantification of membrane proteins in wild-type and prion protein (PrP)-knockout cerebellar granule neurons.

Approximately 25% of eukaryotic proteins possessing homology to at least two transmembrane domains are predicted to be embedded in biological membranes. Nevertheless, this group of proteins is not usually well represented in proteome-wide experiments due to their refractory nature. Here we present a quantitative mass spectrometry-based comparison of membrane protein expression in cerebellar granule neurons grown in primary culture that were isolated from wild-type mice and mice lacking the cellular prion protein.

Protein expression changes in skeletal muscle in response to growth promoter abuse in beef cattle.

The fraudulent treatment of cattle with growth promoting agents (GPAs) is a matter of great concern for the European Union (EU) authorities and consumers. It has been estimated that 10% of animals are being illegally treated in the EU. In contrast, only a much lower percentage of animals (<0.

Cellular prion protein is implicated in the regulation of local Ca2+ movements in cerebellar granule neurons.

The cellular prion protein (PrP(C)) is a cell-surface glycoprotein mainly expressed in the CNS. The structural conversion of PrP(C) generates the prion, the infectious agent causing transmissible spongiform encephalopathies, which are rare and fatal diseases affecting animals and humans. Despite decades of intensive research, the mechanism of prion-associated neurodegeneration and the physiologic role of PrP(C) are still obscure.

Heterogeneous PrPC metabolism in skeletal muscle cells.

Recent reports have shown that prions, the causative agent of transmissible spongiform encephalopathies, accumulate in the skeletal muscle of diseased animals and man. In an attempt to characterise in this tissue the prion protein (PrP(C)), whose conformational rearrangement governs the generation of prions, we have analysed the protein in primary cultured murine myocytes and in different skeletal muscle types. Our results indicate that the expression and cellular processing of PrP(C) change during myogenesis, and in muscle fibres with different contractile properties.

The prion protein and its paralogue Doppel affect calcium signaling in Chinese hamster ovary cells.

The function of the prion protein (PrP(c)), implicated in transmissible spongiform encephalopathies (TSEs), is largely unknown. We examined the possible influence of PrP(c) on Ca(2+) homeostasis, by analyzing local Ca(2+) fluctuations in cells transfected with PrP(c) and Ca(2+)-sensitive aequorin chimeras targeted to defined subcellular compartments. In agonist-stimulated cells, the presence of PrP(c) sharply increases the Ca(2+) concentration of subplasma membrane Ca(2+) domains, a feature that may explain the impairment of Ca(2+)-dependent neuronal excitability observed in TSEs.

Selective and efficient immunoprecipitation of the disease-associated form of the prion protein can be mediated by nonspecific interactions between monoclonal antibodies and scrapie-associated fibrils.

Transmissible spongiform encephalopathies are characterized by the accumulation in brain tissues of an abnormal isoform of the prion protein named PrPsc, which is the only direct marker known for transmissible spongiform encephalopathies. Here we show that PrPsc can be specifically immunoprecipitated by using several monoclonal antibodies (mAbs) of various specificities independently of the properties of their binding site (paratope). These results strongly suggest that a significant proportion of mAbs can interact with PrPsc aggregates through nonspecific paratope-independent interactions allowing selective immunoprecipitation of PrPsc when these mAbs are immobilized on a polydisperse solid phase like microbeads.