Paracrine Diffusion of PrPC and Propagation of Prion Infectivity by Plasma Membrane-Derived Microvesicles

Cellular prion protein (PrPc) is a physiological constituent of eukaryotic cells. The cellular pathways underlying prions spread from the sites of prions infection/peripheral replication to the central nervous system are still not elucidated. Membrane-derived microvesicles (MVs) are submicron (0.1–1 µm) particles, that are released by cells during plasma membrane shedding processes. They are usually liberated from different cell types, mainly upon activation as well as apoptosis, in this case, one of their hallmarks is the exposure of phosphatidylserine in the outer leaflet of the membrane. MVs are also characterized by the presence of adhesion molecules, MHC I molecules, as well as of membrane antigens typical of their cell of origin. Evidence exists that MVs shedding provide vehicles to transfer molecules among cells, and that MVs are important modulators of cell-to-cell communication. In this study we therefore analyzed the potential role of membrane-derived MVs in the mechanism(s) of PrPC diffusion and prion infectivity transmission. We first identified PrPC in association with the lipid raft components Fyn, flotillin-2, GM1 and GM3 in MVs from plasma of healthy human donors. Similar findings were found in MVs from cell culture supernatants of murine neuronal cells. Furthermore we demonstrated that PrPSc is released from infected murine neuronal cells in association with plasma membrane-derived MVs and that PrPSc-bearing MVs are infectious both in vitro and in vivo. The data suggest that MVs may contribute both to the intercellular mechanism(s) of PrPC diffusion and signaling as well as to the process of prion spread and neuroinvasion

Thermosensitive polynorbornene poly(ethylene oxide) nanoparticles loaded with oligoDNAs: an innovative approach for acting on cancer-associated pain

DNA oligonucleotides (oligoDNAs) have been recently identified as a novel class of therapeutic tools for acting on the cancer-associated pain.</p

Serum IgG antibodies to P0 dimer and 35 kDa P0 related protein in neuropathy associated with monoclonal gammopathy

Background: Peripheral neuropathies (PN) associated with monoclonal gammopathy (MG) are widely considered as autoimmune disorders, but the putative role of incriminated antigens is still not understood. Objective: Fifty five patients with PN associated with MG were studied to investigate whether new antigens could be found, and to evaluate their relation to clinical manifestations. Methods: An immunological study was conducted on patient sera to identify autoreactivities against nerve proteins by western blotting. Antigen proteins were purified and analysed by proteomic tools. Correlation with ultrastrucural and clinical features was then studied. Results: Of the 55 patients suffering from PN associated with MG, 17 exhibited IgG autoantibodies directed against peripheral nerve proteins of 35, 58, and 60 kDa. N-terminal microsequencing and mass spectrometry analyses of the 35 kDa protein revealed perfect peptidic matching with 47% of the amino acid sequence of P0, whereas the 58 and 60 kDa proteins were identified as the reduced and non-reduced forms of a P0 dimer. Deglycosylation did not affect IgG binding to the 35 kDa P0 related protein, suggesting a peptidic epitope. In contrast, deglycosylation abolished IgG recognition of the P0 dimer protein, so that a carbohydrate moiety may be implicated in the epitope formation. This confirmed the existence of two different types of IgG, one recognising the 58 and 60 kDa proteins and one directed against the 35 kDa protein. Conclusions: This is the first report of antibody activity directed against the dimeric association of P0. Although P0 oligomerisation and adhesion properties play a crucial part in the myelin sheath compaction, the pathogenic significance of these autoantibodies needs further investigations to be elucidated

Mitochondrial DNA-based identification of developmental stages and empty puparia of forensically important flies (Diptera) in Egypt

Relying on morphology in the estimation of postmortem intervals is not always accurate for all life phases of flies, especially for immature stages. The present study demonstrates the application of cytochrome oxidase I sequences, a partial mitochondrial (mt) gene region, to differentiate forensically important flies in Alexandria, Egypt. Thirty-three adult flies, larvae, and pupae were collected from rabbit carcasses. Nineteen were used for genotyping. Sequence analysis revealed no significant intraspecific divergence in Diptera species. Accordingly, a neighbor-joining tree using the Kimura 2-parameter model illustrated reciprocal morphology between species. Specimens represented five species, four genera, four subfamilies, two families, and one order. We herein identify five different Diptera species, Chrysomya albiceps, Chrysomya megacephala, Calliphora vicina, Lucilia sericata, and Ophyra capensis, using mt DNA as a species-specific marker for identification in a local database set-up

The phosphatidylinositol (PI)-5-phosphate 4-kinase type II enzyme controls insulin signaling by regulating PI-3,4,5-trisphosphate degradation

Phosphatidylinositol-5-phosphate (PI-5-P) is a newly identified phosphoinositide with characteristics of a signaling lipid but no known cellular function. PI-5-P levels are controlled by the type II PI-5-P 4-kinases (PIP4K IIs), a family of kinases that converts PI-5-P into phosphatidylinositol-4,5-bisphosphate (PI-4,5-P(2)). The PI-5-P pathway is an alternative route for PI-4,5-P(2) synthesis as the bulk of this lipid is generated by the canonical pathway in which phosphatidylinositol-4-phosphate (PI-4-P) is the intermediate. Here we examined the effect of activation of the PI-5-P pathway on phosphoinositide 3-kinase (PI3K) signaling by expressing PIP4K IIβ in cells that lack this enzyme. Although PIP4K II generates PI-4,5-P(2), a substrate for PI3K, expression of this enzyme reduced rather than increased phosphatidylinositol-3,4,5-trisphosphate (PI-3,4,5-P(3)) levels in cells stimulated with insulin or cells expressing activated PI3K. This reduction in PI-3,4,5-P(3) levels resulted in decreased activation of the downstream protein kinase, Akt/PKB. Consistent with these results, expression of IpgD, a bacterial phosphatase that converts PI-4,5-P(2) to PI-5-P, resulted in Akt activation, and this effect was partially reversed by PIP4K IIβ. PIP4K IIβ expression did not impair insulin-dependent association of PI3K with insulin receptor substrate 1 (IRS1) but abbreviated Akt activation, indicating that PIP4K II regulates PI-3,4,5-P(3) degradation rather than synthesis. These data support a model in which the PI-5-P pathway controls insulin signaling that leads to Akt activation by regulating a PI-3,4,5-P(3) phosphatase

miR-92a regulates expression of synaptic GluA1-containing AMPA receptors during homeostatic scaling

We investigated whether microRNAs could regulate AMPA receptor expression during activity blockade. miR-92a strongly repressed the translation of GluA1 receptors by binding the 3' untranslated region of rat GluA1 (also known as Gria1) mRNA and was downregulated in rat hippocampal neurons after treatment with tetrodotoxin and AP5. Deleting the seed region in GluA1 or overexpressing miR-92a blocked homeostatic scaling, indicating that miR-92a regulates the translation and synaptic incorporation of new GluA1-containing AMPA receptors