Cone snails employ a fast-acting venom to paralyse their prey. But what is bad news for fish is good news for diabetics. New research suggests the "weaponised insulin" produced by these sea critters is far more efficient than conventional medicines used to treat high blood sugar. A cone snail hunting fish. (Image: Baldomero Olivera)
While hunting, some cone snails secrete insulin, along with other toxic compounds, into the water. When an unsuspecting fish swims by, this poisonous brew causes its blood sugar to plummet, sending the fish into a hypoglycemic trance. Stunned, the fish is easy prey for the cone snail, who engulfs and consumes it. That's why marine biologists refer to this as weaponised insulin.
In a new study published in Nature Structural & Molecular Biology, a research team from the United States and Australia show that this undersea weapon could inspire the development of fast-acting medicines to treat diabetes in humans. A molecular analysis of the cone snail venom revealed its potency; it's much faster than the best rapid-acting therapeutic insulin, and it can begin working in the body in just five minutes. Compare that to the 15 minutes it takes the fastest-acting insulin to kick in.
"You look at what venoms animals make to affect the physiology of their prey, and you use that as a starting point," noted University of Utah biologist Helena Safavi, a co-author of the paper, in a press statement. "You can get new ideas from venoms. To have something that has already been evolved -- that's a huge advantage."
Like cone snails, humans also produce insulin. But instead of using it as a venom, our bodies use it to regulate the amount of glucose in our blood. When the body can't produce enough insulin -- a condition known as diabetes -- it can result in high blood sugar, or hyperglycemia. To prevent this from happening, diabetics receive synthetic insulin injections. (Natural insulin is produced in the pancreas.)
Safavi and her colleagues discovered that cone snail insulin is different than human insulin and synthetic insulin in one very important way: It lacks a molecular segment that causes it to stick to other insulin molecules. This allows it to act fast in the body. Tests on insulin receptors show that snail insulin isn't quite as good as human insulin, but its ability to quickly get to work makes it an attractive candidate for future therapies. More experiments are needed to measure how snail insulin works in the human body, and whether it will function the way the researchers hope it will.
"People think it's easy to make drugs," said Safavi. "But where do you start? You have to have some kind of idea of what a drug should look like, what kind of properties the drug should have, so it's very difficult to design novel drugs." And as her colleague and study co-author Danny Chou aptly put it, "It's really about learning from nature."