Alpine Space Prospective Study. Sustainable territorial development in the Alpine Space: Towards long term transnational cooperation

This "Prospective Study" argues that a long term transnational cooperation will be able to pursue the sustainable territorial development in the Alpine Space only at the condition of a substantial improvement of the current experience. This regards an increased awareness of the complexity of issues and challenges currently at stake in the Alpine area but especially, in this light, the capacity of involving all relevant institutional and socioeconomic stakeholders in the building of shared transnational strategie

Alpine Space Prospective Study. Sustainable territorial development in the Alpine Space: Towards long term transnational cooperation

This "Prospective Study" argues that a long term transnational cooperation will be able to pursue the sustainable territorial development in the Alpine Space only at the condition of a substantial improvement of the current experience. This regards an increased awareness of the complexity of issues and challenges currently at stake in the Alpine area but especially, in this light, the capacity of involving all relevant institutional and socioeconomic stakeholders in the building of shared transnational strategies

Perforin Rapidly Induces Plasma Membrane Phospholipid Flip-Flop

The cytotoxic cell granule secretory pathway is essential for host defense. This pathway is fundamentally a form of intracellular protein delivery where granule proteases (granzymes) from cytotoxic lymphocytes are thought to diffuse through barrel stave pores generated in the plasma membrane of the target cell by the pore forming protein perforin (PFN) and mediate apoptotic as well as additional biological effects. While recent electron microscopy and structural analyses indicate that recombinant PFN oligomerizes to form pores containing 20 monomers (20 nm) when applied to liposomal membranes, these pores are not observed by propidium iodide uptake in target cells. Instead, concentrations of human PFN that encourage granzyme-mediated apoptosis are associated with pore structures that unexpectedly favor phosphatidylserine flip-flop measured by Annexin-V and Lactadherin. Efforts that reduce PFN mediated Ca influx in targets did not reduce Annexin-V reactivity. Antigen specific mouse CD8 cells initiate a similar rapid flip-flop in target cells. A lipid that augments plasma membrane curvature as well as cholesterol depletion in target cells enhance flip-flop. Annexin-V staining highly correlated with apoptosis after Granzyme B (GzmB) treatment. We propose the structures that PFN oligomers form in the membrane bilayer may include arcs previously observed by electron microscopy and that these unusual structures represent an incomplete mixture of plasma membrane lipid and PFN oligomers that may act as a flexible gateway for GzmB to translocate across the bilayer to the cytosolic leaflet of target cells

Perforin activity at membranes leads to invaginations and vesicle formation

The cytotoxic cell granule secretory pathway is essential for immune defence. How the pore-forming protein perforin (PFN) facilitates the cytosolic delivery of granule-associated proteases (granzymes) remains enigmatic. Here we show that PFN is able to induce invaginations and formation of complete internal vesicles in giant unilamellar vesicles. Formation of internal vesicles depends on native PFN and calcium and antibody labeling shows the localization of PFN at the invaginations. This vesiculation is recapitulated in large unilamellar vesicles and in this case PFN oligomers can be seen associated with the necks of the invaginations. Capacitance measurements show PFN is able to increase a planar lipid membrane surface area in the absence of pore formation, in agreement with the ability to induce invaginations. Finally, addition of PFN to Jurkat cells causes the formation of internal vesicles prior to pore formation. PFN is capable of triggering an endocytosis-like event in addition to pore formation, suggesting a new paradigm for its role in delivering apoptosis-inducing granzymes into target cells