For the first time, scientists have created synthetic human prions in the laboratory.
This is a major breakthrough and could help in our understanding of how these infectious proteins give rise to various neurodegenerative diseases such as Creutzfeldt-Jakob disease, and potentially other more common forms of dementia.
Prions are effectively proteins made by the body that have folded incorrectly. Usually, proteins that do this are cleared away and destroyed, but prions instead bind to other proteins and transmit their misfolded state. This results in a honeycomb-like structure that effectively turns the brain into a sponge, leading to progressive neurodegeneration.
But why this happens, and more crucially what can be done to stop it, is difficult to figure out. So far, researchers have been able to create rodent prions, but these are unable to infect human cells and so are limiting in what they can tell us.
Now, however, a team from Case Western Reserve University have managed to insert the human gene that creates the prion protein into E.coli, which then successfully expresses the highly destructive molecule. They have also discovered another specific molecule that seems to be essential in triggering its transmission, known as Ganglioside GM1.
“Until now our understanding of prions in the brain has been limited,” explains Jiri G. Safar, lead author of the paper published in Nature Communications, in a statement. “Being able to generate synthetic human prions in a test tube as we have done will enable us to achieve a much richer understanding of prion structure and replication.”
“This is crucial for developing inhibitors of their replication and propagation throughout the brain, which is essential for halting prion-based brain disease.”
One such target for these inhibitors could be the newly identified Ganglioside GM1. The molecule, known as a cofactor, is thought to modulate cell-to-cell signaling and is crucial in the replication and transmission of prions. This raises the intriguing possibility that by targeting this cofactor, they could potentially slow or even stop the spread of the proteins.
The researchers were also able to show that it was not the misfolding of the protein per se that leads to dementia, but that it occurs in a specific region of the protein known as the C terminal domain.
“Our findings explain at the structural level the emergence of new human prions and provide a basis for understanding how seemingly subtle differences in mis-folded protein structure and modifications affect their transmissibility, cellular targeting, and thus manifestation in humans,” says Safar.
This work should allow more relevant studies to be conducted on the proteins, and hopefully lead to new treatments.
