Pore-forming toxins from sea anemones: from protein-membrane interaction to its implications for developing biomedical applications

Actinoporins are pore-forming proteins produced by sea anemones which have aroused the interest of the scientific community due to their unique properties. Secreted in soluble form, they undergo conformational changes leading to pore-formation in the cell membrane. These processes have been carefully examined over the last few years although we are still far from fully understanding them. It is clear that actinoporins show a high affinity for sphingomyelin, a ubiquitous sphingophospholipid in the membrane of eukaryotic organisms, but other membrane components and the bilayer physico-chemical properties regulate their pore-forming activity as well. In this chapter we present a general overview of the structural properties of actinoporins and the discussion on the pore structure with particular focus on sticholysins, two actinoporins widely studied in our laboratory. Our main interest is to show in greater depth the biomedical and biotechnological applications that are under development based on the high cytotoxic capacity of these proteins. First, we describe the main alterations that these cytolysins cause to simple cells such as mammal non-nucleated erythrocytes and then to the more complex ones, including tumor and non-tumor eukaryotic cells. The advances in the construction of immunotoxins directed against undesirable cells, particularly tumor cells, and the development of a vaccine platform against cancer are described in more detail and are among the most promising potential applications of this toxin family.