TOXIC EFFECTS OF THE NOVEL PROTEIN UPI FROM THE SEA-ANEMONE URTICINA-PISCITVORA

UpI is a basic protein, with molecular mass (similar to 28 kDa) and a pI>9.4, isolated from the sea anemone Urticina piscivora. It is a pote nt cardiac stimulatory protein with the partial amino acid sequence K( 15)AKDLT(20)AGASY(25)LTKEA(30)GCTKL(35)QAGCT(40) MYQAY(45)N [1]. The t oxic effects of UpI and the crude extract from which it was isolated h ave been investigated on three tumour cell lines: KB, L1210, and HEL 2 99 cells. UpI, however, was less potent on each cell line than the cru de extract. Since previous experiments had shown extracts of U. pisciv ora to be haemolytic on erythrocytes of rat, guinea pig and dog, the h aemolytic action of UpI was investigated. It was found to be a potent haemolysin on erythrocytes of rat, guinea pig, dog, pig and human, cau sing haemolysis on erythrocytes of each species tested at concentratio ns as low as 10(-10) M. Haemolysis was inhibited in a concentration-de pendent manner by the phospholipid sphingomyelin but not cholesterol. Using scanning electron microscopy, it is now being shown that UpI pro duces significant structural damage to membranes of erythrocytes from rat and guinea pig. It proved to be a potent ichthyotoxin. These data suggest that sea anemone toxin not only possess different pharmacologi cal activities but that UpI, one of the active constituents, could be responsible for the different pharmacological effects exhibited by the crude extract. (C) 1995 The Italian Pharmacological Society