The Cellular Prion Protein Interacts with the Tissue Non-Specific Alkaline Phosphatase in Membrane Microdomains of Bioaminergic Neuronal Cells

BACKGROUND: The cellular prion protein, PrP(C), is GPI anchored and abundant in lipid rafts. The absolute requirement of PrP(C) in neurodegeneration associated to prion diseases is well established. However, the function of this ubiquitous protein is still puzzling. Our previous work using the 1C11 neuronal model, provided evidence that PrP(C) acts as a cell surface receptor. Besides a ubiquitous signaling function of PrP(C), we have described a neuronal specificity pointing to a role of PrP(C) in neuronal homeostasis. 1C11 cells, upon appropriate induction, engage into neuronal differentiation programs, giving rise either to serotonergic (1C11(5-HT)) or noradrenergic (1C11(NE)) derivatives. METHODOLOGY/PRINCIPAL FINDINGS: The neuronal specificity of PrP(C) signaling prompted us to search for PrP(C) partners in 1C11-derived bioaminergic neuronal cells. We show here by immunoprecipitation an association of PrP(C) with an 80 kDa protein identified by mass spectrometry as the tissue non-specific alkaline phosphatase (TNAP). This interaction occurs in lipid rafts and is restricted to 1C11-derived neuronal progenies. Our data indicate that TNAP is implemented during the differentiation programs of 1C11(5-HT) and 1C11(NE) cells and is active at their cell surface. Noteworthy, TNAP may contribute to the regulation of serotonin or catecholamine synthesis in 1C11(5-HT) and 1C11(NE) bioaminergic cells by controlling pyridoxal phosphate levels. Finally, TNAP activity is shown to modulate the phosphorylation status of laminin and thereby its interaction with PrP. CONCLUSION/SIGNIFICANCE: The identification of a novel PrP(C) partner in lipid rafts of neuronal cells favors the idea of a role of PrP in multiple functions. Because PrP(C) and laminin functionally interact to support neuronal differentiation and memory consolidation, our findings introduce TNAP as a functional protagonist in the PrP(C)-laminin interplay. The partnership between TNAP and PrP(C) in neuronal cells may provide new clues as to the neurospecificity of PrP(C) function

Revisiting the genetic diversity of emerging hantaviruses circulating in Europe using a pan-viral resequencing microarray

Hantaviruses are zoonotic agents transmitted from small mammals, mainly rodents, to humans, where they provoke diseases such as Hemorrhagic fever with Renal Syndrome (HFRS) and its mild form, Nephropathia Epidemica (NE), or Hantavirus Cardio-Pulmonary Syndrome (HCPS). Hantaviruses are spread worldwide and monitoring animal reservoirs is of primary importance to control the zoonotic risk. Here, we describe the development of a pan-viral resequencing microarray (PathogeniD v3.0) able to explore the genetic diversity of rodent-borne hantaviruses endemic in Europe. Among about 800 sequences tiled on the microarray, 52 correspond to a tight molecular sieve of hantavirus probes covering a large genetic landscape. RNAs from infected animal tissues or from laboratory strains have been reverse transcribed, amplified, then hybridized to the microarray. A classical BLASTN analysis applied to the sequence delivered through the microarray allows to identify the hantavirus species up to the exact geographical variant present in the tested samples. Geographical variants of the most common European hantaviruses from France, Germany, Slovenia and Finland, such as Puumala virus, Dobrava virus and Tula virus, were genetically discriminated. Furthermore, we precisely characterized geographical variants still unknown when the chip was conceived, such as Seoul virus isolates, recently emerged in France and the United Kingdom

Le phénomène Prion, différents aspects d'un nouveau concept en biologie

International audiencePrion diseases are neurodegenerative disorders causing spongiform encephalopthies in mammals. They have the peculiarity of being transmissible and have led to epidemics such as Kuru in human, scrapie in sheep, chronic wasting disease in cervids and mad cow in bovine. This latter has been transmitted to human where it has induced a variant form of the human Creutzfeldt-Jakob disease. Amyloïd deposits of a misfolded protein (PrPSc) due to the conformational change of the host encoded cellular prion protein (PrPC) are features of these diseases. The prion hypothesis has proposed PrPSc to be the infectious agent. Recent arguments in favor of this hypothesis will be reviewed. The puzzling prion strain phenomenon leading to different pathologies and the nature of the infectious particle will also be questioned. The Prion concept, in addition to apply to diseases, has allowed a better understanding of some epigenetics transmissions in fungi. Principle of this concept suggests that different protein conformations may carry and propagate various information opening the way to new investigations on amyloïdosis and their potential to be transmitted. Several examples of Prion-like phenomena not systematically associated with diseases but related to functional amyloïds, sustain a conceptual novelty in biology that will be discussed.Les maladies à prions sont des maladies neurodégénératives responsables d’encéphalopathies spongiformes chez les mammifères, ayant la particularité d’être transmissibles. Elles ont ainsi provoqué des épidémies (Kuru chez l’homme, tremblante du mouton, dépérissement chronique des cervidés, vache folle) et ont conduit à l’émergence d’un variant de la maladie de Creutzfeldt-Jakob après transmission inter-espèce de l’agent bovin à l’homme. Elles sont caractérisées par des dépôts amyloïdes constitués d’une protéine de structure anormale, la PrPSc qui résulte de la conversion de la protéine prion cellulaire (PrPC) de l’hôte et qui, selon l’hypothèse Prion, constituerait l’agent infectieux. Cette revue présente les arguments récents appuyant cette hypothèse. L’intriguant phénomène de souches associées à des pathologies différentes et la caractérisation de la particule infectieuse seront également abordés. Par ailleurs, le concept prion qui dépasse maintenant le cadre de ces maladies, a permis de réévaluer certains événements épigénétiques décrits chez les champignons. Ce concept, en suggérant un principe tel que diverses structures d’une même protéine puissent porter des informations différentes, a permis d’élargir le champ des investigations sur les amyloïdoses et leur transmissibilité potentielle. L’existence de phénomènes de type Prion impliqués dans des fonctions non systématiquement associées à des pathologies, apporte une nouveauté conceptuelle en biologie

LES MALADIES À PRIONS ET LE CONCEPT PRION Complexité, structures dynamiques, organisation du vivant

http://www.nicolasbouleau.eu/histoire-des-sciences/concept-de-prion/Ce texte sur les prions est né de nos nombreuses discussions et s’est construit autour de questions. Bien que détaillé pour la compréhension, il a été rédigé de façon à pouvoir être lu à différents niveaux par des lecteurs intéressés provenant d’horizons différents. Le résultat en est une revue documentée à partir d’éléments puisés dans la littérature scientifique sur les prions et, au-delà des maladies qui lui sont associées, sur le concept prion. Le phénomène prion qui renverse certains dogmes de génétique moléculaire est en effet un bon prétexte pour débattre d’exemples qui nous intéressent, illustrant la diversité des modes de fonctionnement du vivant et leur complexité. Cette revue montre, comme c’est d’ailleurs souvent le cas en science, comment un processus non conventionnel peut rendre compte de phénomènes non compris d’autres domaines qui peuvent sembler éloignés. L’idée de cette revue comme l’indique son sous-titre, est d’ouvrir à une réflexion sur le thème de la complexité qui bien sûr pourrait être illustré par bien d’autres exemples. Il est à espérer que cette première revue sera suivie d’autres textes abordant des problématiques variées qui viendront enrichir cette discussion

TNAP, an Essential Player in Membrane Lipid Rafts of Neuronal Cells

International audienceThe tissue non-specific alkaline phosphatase (TNAP) is a glycosyl-phosphatidylinositol (GPI) anchored glycoprotein which exists under different forms and is expressed in different tissues. As the other members of the ecto-phosphatase family, TNAP is targeted to membrane lipid rafts. Such micro domains enriched in particular lipids, are involved in cell sorting, are in close contact with the cellular cytoskeleton and play the role of signaling platform. In addition to its location in functional domains, the extracellular orientation of TNAP and the fact this glycoprotein can be shed from plasma membranes, contribute to its different phosphatase activities by acting as a phosphomonoesterase on various soluble substrates (inorganic pyrophosphate -PPi-, pyridoxal phosphate -PLP-, phosphoethanolamine -PEA-), as an ectonucleotidase on nucleotide-phosphate and presumably as a phosphatase able to dephosphorylate phosphoproteins and phospholipids associated to cells or to extra cellular matrix. More and more data accumulate on an involvement of the brain TNAP both in physiological and pathological situations. This review will summarize what is known and expected from the TNAP localization in lipid rafts with a particular emphasis on the role of a neuronal microenvironment on its potential function in the central nervous system

What Do We Know about How Hantaviruses Interact with Their Different Hosts?

Hantaviruses, like other members of the Bunyaviridae family, are emerging viruses that are able to cause hemorrhagic fevers. Occasional transmission to humans is due to inhalation of contaminated aerosolized excreta from infected rodents. Hantaviruses are asymptomatic in their rodent or insectivore natural hosts with which they have co-evolved for millions of years. In contrast, hantaviruses cause different pathologies in humans with varying mortality rates, depending on the hantavirus species and its geographic origin. Cases of hemorrhagic fever with renal syndrome (HFRS) have been reported in Europe and Asia, while hantavirus cardiopulmonary syndromes (HCPS) are observed in the Americas. In some cases, diseases caused by Old World hantaviruses exhibit HCPS-like symptoms. Although the etiologic agents of HFRS were identified in the early 1980s, the way hantaviruses interact with their different hosts still remains elusive. What are the entry receptors? How do hantaviruses propagate in the organism and how do they cope with the immune system? This review summarizes recent data documenting interactions established by pathogenic and nonpathogenic hantaviruses with their natural or human hosts that could highlight their different outcomes

Role of the cytosolic tails of Rift Valley fever virus envelope glycoproteins in viral morphogenesis

International audienceThe correct folding, heterodimerization and trafficking of Gn/Gc envelope glycoproteins of Rift Valley fever virus, RVFV (Bunyaviridae and Phlebovirus genus) are essential for Golgi assembly and budding of viral particles. The Gn and Gc carboxy-terminus contain a Golgi targeting and an ER-retrieval signal, respectively. We generated RVFV-like particles with mutations in the cytosolic tails of Gn or Gc and identified regions important for release of infectious particles. The role of specific amino-acids in these regions was further investigated by creating recombinant mutant viruses by reverse-genetics. Residues outside the suspected Golgi targeting motif, i.e. the di-lysine K29-K30 motif and the N43, R44 and I46 residues of the Gn cytosolic domain, appeared important for Golgi localization and RNP packaging. Concerning the Gc tail, replacement of K2 or K3 in the di-lysine motif, had a drastic impact on Gn trafficking and induced an important organelle redistribution and cell remodeling, greatly affecting particle formation and release

Glycosylation-related genes are variably expressed depending on the differentiation state of a bioaminergic neuronal cell line: implication for the cellular prion protein

Chantier qualité GAA striking feature of the cellular prion protein (PrPC) is the heterogeneity of its glycoforms, whose contribution to PrPC function has yet to be defined. Using the 1C11 neuronal bioaminergic differentiation model and a glycomics approach, we show here a correlation between differential PrPC N-glycosylations in 1C115-HT serotonergic and 1C11NE noradrenergic cells compared to their 1C11 precursor cells and a variation of the glycogenome expression status in these cells. In particular, expression of genes involved in N-glycan synthesis or in the modeling of chondroitin and heparan sulfate proteoglycans appeared to be modulated. Our results highlight that, the expression of glycosylation-related genes is regulated during bioaminergic neuronal differentiation, consistent with a participation of glycoconjugates in neuronal development and plasticity. A neuronal regulation of glycosylation processes may have direct implications on some neurospecific functions of PrPC and may participate in specific brain targeting of prion strains