Washington: Japanese scientists have claimed that a number of toxins found in snake venom could help develop new therapies for chronic diseases like heart attack, stroke and cancer. The scientists, who reported their findings in theJournal of Biological Chemistry, said that inhibiting aprotein found on the surface of blood cells known as plateletsmay combat both irregular blood clotting and the spread ofcertain cancers throughout the body.
Others potently activate platelets, which results in bloodclots," said Yonchol Shin, an associate professor at KogakuinUniversity who specialises in snake toxins. "Identification of the molecular targets of many of thesetoxins has made an enormous contribution to our understandingof platelet activation and related diseases." In 2000, researchers had come across a protein on thesurface of platelets, called CLEC-2. At the time, it remainedunclear how CLEC-2 was produced or what its job was, but theteam suspected it was worth further study. In 2006, the team discovered how rhodocytin -- a moleculepurified from the venom of the Southeast Asia pit viperCalloselasma rhodastoma -- binds to the CLEC-2 receptorprotein on the platelet surface, spurring the platelet to clotwith others like it. Then, in 2007, Suzuki-Inoue and her colleagues reportedhow a separate molecule, called podoplanin, binds to theCLEC-2 platelet receptor protein very much like the venommolecule does. "To shield themselves from the immune system, cancercells send out a chemical, podoplanin, which binds to theCLEC-2 receptor protein on platelets, telling the platelets toget together and form a protective barrier around the cancercells," Suzuki-Inoue explained. "Once enveloped, the cancer cells are not detected by theimmune system and are able to bind to blood vessels` innerlinings and spread, or metastasise, throughout the body." Using a mouse model, the team in 2008 showed thatblocking the tumour protein podoplanin from binding with theplatelet receptor protein CLEC-2 could prevent tumours frommetastasising to the lung. The recent investigations by the team hinged on thegeneration and study of genetically engineered mouse embryosthat lacked the platelet receptor protein CLEC-2.
In the end, the experiments showed that CLEC-2 is notonly necessary for blood clotting but also necessary for thedevelopment of a different type of vessel, specificallylymphatic vessels that carry fluid away from tissues andprevent swelling, or edema. It has been known that tumours generate blood vessels topromote their growth, and the scientists found thatinteraction between the platelet`s CLEC-2 protein and thepodoplanin molecule in lymphatic cells plays an essential rolein this process. "If this is the case, a drug that blocks that interactionwould prevent the spread of tumours through lymphaticvessels," the researchers said. PTI
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