Can Proteins kill you? | Earth Lab

Can Proteins kill you? | Earth Lab


Proteins. They’re a major part of our everyday
diet – they’re in chicken, eggs and my favourite – cottage cheese. Proteins are needed to make your muscles move,
to make your nerves fire, they’re pretty much involved in almost everything that your
body does. So surely something that is a major chunk
of our food intake, and a big deal in the makeup of our bodies, couldn’t hurt us could
they? Well, yeah. There is a protein that could kill you. And it’s called a prion. All proteins are made from long chains of
building blocks – amino acids – that are intricately folded up into specific three dimensional
shapes. The shape determines a protein’s function, so if the shape changes, the protein
doesn’t work. A prion, it turns out, is a normal protein
that has somehow been folded up wrongly, like tangled up headphones in your pocket – and
we all know how frustrating that can be. But the real problem comes when the misfolded
prion comes into contact with other proteins. Just like putting a neat set of headphones
in with your tangled set, you know its going to end up in one huge mess. The misfolded prion protein acts as a template
to tell its neighbours to also twist and contort incorrectly. Each of those then changes its
neighbour, and it starts an exponential cascade of pathologic proportions. Without the right shape, the proteins in the
brain can’t do their job properly, and the brain itself grinds to an erratic, but inevitable
halt. But where do these chaos-causing proteins
come from? For that, we need to turn to two very different
groups of people – the cannibalistic Fore tribe of Papua New Guinea, and the family
of an 18th Century Venetian doctor. Both the Fore and the Venetians were once
medical mysteries, thanks to the strange and terrible diseases that afflicted them. At first glance, the symptoms were very very
different. Many of the members of the Venetian family were completely unable to sleep, for
months at a time, until they died of apparent exhaustion and organ failure. Their affliction
became known as Fatal Familial Insomnia. Whereas, on the other side of the world, the
Papua New Guineans were struck with uncontrollable shaking and laughter along with mental decline.
Their disease was named Kuru, which means ‘to shake’, or alternatively named the
macabre ‘Laughing Disease’. Despite their differences though, autopsies
of both groups revealed that all of their brains were full of tiny holes, where normal
grey and white matter should have been. Both groups had forms of what’s known now
as TSE – transmissible spongiform encephalopathy. A human version of mad cow disease in cattle
and Scrapie in sheep. Other symptoms of TSE included difficulty
speaking, unsteadiness when walking, and severe mental deterioration over a couple of months
before, invariably, death. It was vicious and unstoppable, and for a
long time, medical professionals had no idea what caused it. Most infectious diseases are caused by pathogenic
agents like bacteria, viruses, parasites. But the sufferers of TSE seemed to have no
such infection. What could be so powerful to cause a brain
to so suddenly and irreversibly begin to eat itself? Theories were thrown around, but for
many years there was simply no proof. It wasn’t until the 1980s that an American
scientist, Stanley B. Prusiner, managed to find and isolate the cause of TSE. And you’ve guessed it, it was the prion. One of the things that makes prions so terrifying,
is that there’s more than one way they can get into your brain. Like many normal pathogens, they are infectious,
meaning that if you come into contact with affected tissues, the prions can make the
leap to you. That’s what happened to the Fore tribe. As a mark of love and respect to their dead,
their funeral rites involved extracting and eating the brains of the deceased. Once one person died of Kuru, this morbid
tradition led to countless more being infected. Thankfully though, once it was found that
literally eating brains was the cause of the brain-eating disease, the Fore people found
other ways to honour their dead, and the Laughing Disease is all but gone from Papua New Guinea. However, the Venetians aren’t known for
eating brains, so they must have contracted their prion disease in another way. As well as being infectious, prions are also
hereditary, meaning that the instructions for them can be carried in a family’s genes
and passed on to future generations. And so, thanks to a potently tangled protein,
fatal familial insomnia has been killing members of the same Italian family for over 250 years.
And sadly, it continues to do so today, because there is no known cure for prion diseases
– the proteins themselves are ridiculously difficult to destroy. And they can lay dormant
for decades before triggering the disease, and they can even be transmitted from animals
to humans. In the UK 150 people have died from TSE to
date, although several thousand are thought to be infected with dormant prions. It’s genuinely scary stuff. But while we wait for science to fill the
gaps in our knowledge about these deadly proteins, the Fore tribe can give us at least one ray
of hope. A simple lesson, and one that I feel we should
all try to live by. Don’t, if you can manage it, eat other people’s brains… If this wasn’t all too gruesome for you,
give us a like and check out our other videos here at BBC Earth Lab. Click to subscribe and be notified of new
videos, and remember kids, don’t eat brains. If you remember one thing today, its that.

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