The wonderfully adorable egg-laying mammal known as the platypus may hold the key to
new treatments for type 2 diabetes in humans. In particular, the platypus’ venom contains an insulin-regulating hormone that can lower blood glucose levels.
Endemic to Eastern Australia, the duck-billed platypus is somewhat of an evolutionary oddity. Besides its whimsical appearance, the platypus is one in a handful of living mammals that lays eggs instead of giving live birth. In addition, the platypus has 10 sex chromosomes, as compared to our meager 2.
But these characteristics were not what drew researchers from the University of Adelaide and Flinders University. Instead, the scientists were interested in the platypus stomach, or lack thereof. "We knew from genome analysis that there was something weird about the platypus's metabolic control system because they basically lack a functional stomach,” said Frank Grutzer, the lead researcher.
Instead of a stomach, the platypus seems to secrete a gut hormone that regulates their blood glucose levels. The hormone, known as glucagon-like peptide-1 (GLP-1), is also made in humans too; however, some people don’t have enough and the hormone degrades very quickly.
But further research revealed that the platypus has another reservoir for GLP-1 – in the spurs on the heels of their hind feet. "We've discovered conflicting functions of GLP-1 in the platypus: in the gut as a regulator of blood glucose, and in venom to fend off other platypus males during breeding season. This tug of war between the different functions has resulted in dramatic changes in the GLP-1 system," said Briony Forbes, associate professor at the Flinders University's School of Medicine, and the study’s co-lead author.
While the human version of GLP-1 degrades in a flash, the platypus version appears to have evolved to be long-lasting – a quality that makes it highly desirable for the treatment of type 2 diabetes. "Our research team has discovered that monotremes -- our iconic platypus and echidna -- have evolved changes in the hormone GLP-1 that make it resistant to the rapid degradation normally seen in humans," said Grutzner.
"We've found that GLP-1 is degraded in monotremes by a completely different mechanism. Further analysis of the genetics of monotremes reveals that there seems to be a kind of molecular warfare going on between the function of GLP-1, which is produced in the gut but surprisingly also in their venom," Grutzner explained.
"This is an amazing example of how millions of years of evolution can shape molecules and optimize their function,” said Grutzner. "These findings have the potential to inform diabetes treatment, one of our greatest health challenges, although exactly how we can convert this finding into a treatment will need to be the subject of future research."
Additional sources:
BBC,
University of Adelaide
