Measuring the Acceptability of Interurban Road Pricing Among Different Groups of Stakeholders. The Case of Spain

The European Commission is seeking ways to promote both the harmonization of transport policies among its constituent members and the homogenization of transport market conditions. The main goal is to insure that each transport mode pays for the true social and economic costs produced by it: transport taxes and prices should vary according to infrastructure damage, degree of congestion, risk of accidents and the expenses they cause, and environmental nuisances and damage. However, it is difficult to modify the present national systems in favor of a European-wide one, because every country has different perceptions of the need and reasons to implement such a European-wide system. Spain, like other EU countries, is considering the European transport policy and the related regulations which are intended to homogenize the present fragmented road pricing schemes. In Spain, different groups of road stakeholders (road freight and passengers’ operators, highway concessionaires, and associations of private car users) have experience with toll roads dating back to the 1960s. But a recent study of transport pricing, the Spanish Road Pricing Model (META), had as one of its aims the capture of different degrees of acceptance of a generalized road pricing system, and demonstrated that these stakeholders are still not willing to fully pay for the external costs (environmental and road safety costs) of the road network. The low approval rates raises questions about the most effective way for Spanish governmental bodies, those that are administratively responsible, to introduce a generalized tolling scheme

AMPA Receptors Commandeer an Ancient Cargo Exporter for Use as an Auxiliary Subunit for Signaling

Fast excitatory neurotransmission in the mammalian central nervous system is mainly mediated by ionotropic glutamate receptors of the AMPA subtype (AMPARs). AMPARs are protein complexes of the pore-lining α-subunits GluA1-4 and auxiliary β-subunits modulating their trafficking and gating. By a proteomic approach, two homologues of the cargo exporter cornichon, CNIH-2 and CNIH-3, have recently been identified as constituents of native AMPARs in mammalian brain. In heterologous reconstitution experiments, CNIH-2 promotes surface expression of GluAs and modulates their biophysical properties. However, its relevance in native AMPAR physiology remains controversial. Here, we have studied the role of CNIH-2 in GluA processing both in heterologous cells and primary rat neurons. Our data demonstrate that CNIH-2 serves an evolutionarily conserved role as a cargo exporter from the endoplasmic reticulum (ER). CNIH-2 cycles continuously between ER and Golgi complex to pick up cargo protein in the ER and then to mediate its preferential export in a coat protein complex (COP) II dependent manner. Interaction with GluA subunits breaks with this ancestral role of CNIH-2 confined to the early secretory pathway. While still taking advantage of being exported preferentially from the ER, GluAs recruit CNIH-2 to the cell surface. Thus, mammalian AMPARs commandeer CNIH-2 for use as a bona fide auxiliary subunit that is able to modify receptor signaling

THE IMMUNOSUPPRESSIVE EFFECT OF MESENCHYMAL STROMAL CELLS ON B LYMPHOCYTES IS MEDIATED BY MEMBRANE VESICLES.

The immunomodulatory properties of mesenchymal stromal cells are the subject of increasing interest and of widening clinical applications, but the reproducibility of their effects is controversial and the underlying mechanisms have not been fully clarified. We investigated the transfer of membrane vesicles, a recently recognized pathway of intercellular communication, as possible mediator of the interaction between mesenchymal stromal cells and B lymphocytes. Mesenchymal stromal cells exhibited a strong dose-dependent inhibition of B cell proliferation and differentiation in a CpG-stimulated peripheral blood mononuclear cell co-culture system. We observed that these effects could be fully reproduced by membrane vesicles isolated from mesenchymal stromal cell culture supernatants, in a dose-dependent fashion. Next, we evaluated the localization of fluorescent labeled membrane vesicles within specific cell subtypes both by flow cytometry and by confocal microscopy analysis. Membrane vesicles were found to be associated with stimulated B lymphocytes, but not with other cell phenotypes (T lymphocytes, dendritic cells, NK cells), in peripheral blood mononuclear cell culture. These results suggest that membrane vesicles derived from mesenchymal stromal cells are the conveyors of the immunosuppressive effect on B lymphocytes. These particles should be further evaluated as immunosuppressive agents in place of the parent cells, with possible advantages in term of standardization, safety and feasibility

Activity-dependent NMDA receptor degradation mediated by retrotranslocation and ubiquitination

The extracellular N-terminal domain (NTD) is the largest region of NMDA receptors; however, biological roles for this ectodomain remain unknown. Here, we determined that the F-box protein, Fbx2, bound to high-mannose glycans of the NR1 ectodomain. F-box proteins specify ubiquitination by linking protein substrates to the terminal E3 ligase. Indeed, ubiquitination of NR1 was increased by Fbx2 and diminished by an Fbx2 dominant-negative mutant. When expressed in hippocampal neurons, this Fbx2 dominant-negative mutant augmented NR1 subunit levels and NMDA receptor-mediated currents in an activity-dependent fashion. These results suggest that homeostatic control of synaptic NR1 involves receptor retrotranslocation and degradation by the ubiquitin-proteasome pathway