30 research outputs found

    Evidence of Presynaptic Localization and Function of the c-Jun N-Terminal Kinase

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    The c-Jun N-terminal kinase (JNK) is part of a stress signalling pathway strongly activated by NMDA-stimulation and involved in synaptic plasticity. Many studies have been focused on the post-synaptic mechanism of JNK action, and less is known about JNK presynaptic localization and its physiological role at this site. Here we examined whether JNK is present at the presynaptic site and its activity after presynaptic NMDA receptors stimulation. By using N-SIM Structured Super Resolution Microscopy as well as biochemical approaches, we demonstrated that presynaptic fractions contained significant amount of JNK protein and its activated form. By means of modelling design, we found that JNK, via the JBD domain, acts as a physiological effector on T-SNARE proteins; then using biochemical approaches we demonstrated the interaction between Syntaxin-1-JNK, Syntaxin-2-JNK, and Snap25-JNK. In addition, taking advance of the specific JNK inhibitor peptide, D-JNKI1, we defined JNK action on the SNARE complex formation. Finally, electrophysiological recordings confirmed the role of JNK in the presynaptic modulation of vesicle release. These data suggest that JNK-dependent phosphorylation of T-SNARE proteins may have an important functional role in synaptic plasticity

    Simulated microgravity induces nuclear translocation of Bax and BCL-2 in glial cultured C6 cells

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    Alterations in the control of apoptotic processes were observed in cells during space flight or under simulated microgravity, the latter obtained with the 3D-Random Positioning Machine (3D-RPM). Usually the proteins Bax and Bcl-2, act as pro- or anti-apoptotic regulators. Here we investigated the effects of simulated microgravity obtained by the 3D-RPM on cell viability, localization and expression of Bax and Bcl-2 in cultures of glial cancerous cells. We observed for the first time a transient cytoplasmic/nuclear translocation of Bax and Bcl-2 triggered by changing gravity vector. Bax translocates into the nucleus after 1 h, is present simultaneously in the cytoplasm after 6 h and comes back to the cytoplasm after 24 h. Bcl-2 translocate into the nucleus only after 6 h and comes back to the cytoplasm after 24 h. Physiological meaning, on the regulation of apoptotic event and possible applicative outcomes of such finding are discussed

    Pharmacological Agents Targeting the Cellular Prion Protein

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    Prion diseases are associated with the conversion of the cellular prion protein (PrPC), a glycoprotein expressed at the surface of a wide variety of cell types, into a misfolded conformer (the scrapie form of PrP, or PrPSc) that accumulates in brain tissues of affected individuals. PrPSc is a self-catalytic protein assembly capable of recruiting native conformers of PrPC, and causing their rearrangement into new PrPSc molecules. Several previous attempts to identify therapeutic agents against prion diseases have targeted PrPSc, and a number of compounds have shown potent anti-prion effects in experimental models. Unfortunately, so far, none of these molecules has successfully been translated into effective therapies for prion diseases. Moreover, mounting evidence suggests that PrPSc might be a difficult pharmacological target because of its poorly defined structure, heterogeneous composition, and ability to generate different structural conformers (known as prion strains) that can elude pharmacological intervention. In the last decade, a less intuitive strategy to overcome all these problems has emerged: targeting PrPC, the common substrate of any prion strain replication. This alternative approach possesses several technical and theoretical advantages, including the possibility of providing therapeutic effects also for other neurodegenerative disorders, based on recent observations indicating a role for PrPC in delivering neurotoxic signals of different misfolded proteins. Here, we provide an overview of compounds claimed to exert anti-prion effects by directly binding to PrPC, discussing pharmacological properties and therapeutic potentials of each chemical class

    Dual-point FDG-PET/CT for treatment response assessment in Hodgkin lymphoma, when an FDG-avid lesion persists after treatment

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    FDG-PET/CT (PET) is now considered the standard imaging tool for Hodgkin Lymphoma (HL) staging and restaging. However a CT-detected residual mass at the end of therapy (EoT) is still a challenge for PET interpretation. The aim of our study was to improve the overall accuracy of EoT PET/CT by using a dynamic dual-point scanning at 60 and 120 after FDG injection (2P-PET/CT). Fifty-one HL patients showing a single residual FDG-avid mass (SFAM) at EoT PET/CT were included in the study in Italy and Poland. Treatment was ABVD, ABVD followed by BEACOPP or ABVD plus radiotherapy. Only patients with a SFAM and a Deauville score (DS) > 2 in EoT PET/CT were included in the study. Two independent nuclear medicine reviewed images with a semi-quantitative analysis (SUVMax and retention index, RI) and a visual scoring according to DS. Compared to standard PET, 2P-PET/CT showed only a modest increase in NPV and PPV, from 0.87 to 0.89 and of the PPV from 0.67 to 0.71, respectively. Increase of the overall accuracy became substantial upon including in the analysis only patients whose images were acquired in strict adhesion to original protocol of 2P-PET/CT scanning: (t 120'-6040 min): the sensitivity increased from 0.60 to 1.00, PPV from 0.75 to 0.83 and NPV from 0.89 to 1. This study, with caution for the small number of patients included, seems to suggest that 2P-PET/CT could increase the overall accuracy of EoT PET/CT in correctly classifying treatment response in HL with a persisting SFAM at EoT

    An antipsychotic drug exerts anti-prion effects by altering the localization of the cellular prion protein

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    <div><p>Prion diseases are neurodegenerative conditions characterized by the conformational conversion of the cellular prion protein (PrP<sup>C</sup>), an endogenous membrane glycoprotein of uncertain function, into PrP<sup>Sc</sup>, a pathological isoform that replicates by imposing its abnormal folding onto PrP<sup>C</sup> molecules. A great deal of evidence supports the notion that PrP<sup>C</sup> plays at least two roles in prion diseases, by acting as a substrate for PrP<sup>Sc</sup> replication, and as a mediator of its toxicity. This conclusion was recently supported by data suggesting that PrP<sup>C</sup> may transduce neurotoxic signals elicited by other disease-associated protein aggregates. Thus, PrP<sup>C</sup> may represent a convenient pharmacological target for prion diseases, and possibly other neurodegenerative conditions. Here, we sought to characterize the activity of chlorpromazine (CPZ), an antipsychotic previously shown to inhibit prion replication by directly binding to PrP<sup>C</sup>. By employing biochemical and biophysical techniques, we provide direct experimental evidence indicating that CPZ does not bind PrP<sup>C</sup> at biologically relevant concentrations. Instead, the compound exerts anti-prion effects by inducing the relocalization of PrP<sup>C</sup> from the plasma membrane. Consistent with these findings, CPZ also inhibits the cytotoxic effects delivered by a PrP mutant. Interestingly, we found that the different pharmacological effects of CPZ could be mimicked by two inhibitors of the GTPase activity of dynamins, a class of proteins involved in the scission of newly formed membrane vesicles, and recently reported as potential pharmacological targets of CPZ. Collectively, our results redefine the mechanism by which CPZ exerts anti-prion effects, and support a primary role for dynamins in the membrane recycling of PrP<sup>C</sup>, as well as in the propagation of infectious prions.</p></div
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