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This Protein Could Be Spreading Type 2 Diabetes Like Mad Cow Disease

New clues.

MIKE MCRAE
2 AUG 2017
 

A type of misbehaving protein might be behind some cases of type 2 diabetes, indicating the condition could potentially be contracted through blood transfusions and organ transplants, or passed to children before birth.

While a lot more research needs to be done to determine if the risks to the general public are in any way significant, the find has established a new area of study in how the disease develops and spreads inside individuals.

 

Led by researchers from the University of Texas, the study used mice to test whether clumps of a misfolded protein called amyloid polypeptide (IAPP) taken from a pancreas can spread and produce diabetes-like symptoms when transferred between individuals.

Unlike its sister disease type 1 diabetes, type 2 – or diabetes mellitus – is a condition that forms over time, reducing a person's ability to produce or respond to insulin.

The disease is far more common that type 1, affecting just under half a billion people worldwide, but its exact causes are still vague. Researchers have identified genetic and environmental factors, but there is still a lot to learn about how many people develop the condition.

Toxic clumps of misfolded proteins similar to those in neurological disorders such as Alzheimer's disease have previously been associated with type 2 diabetes. But finding a link isn't the same thing as identifying a cause, so researchers have now taken a closer look at the amyloid proteins in the pancreas to trace their pathology.

Proteins such as IAPP can twist into forms that are more likely to clump as a result of mutations, which has also been identified in a number of people with type 2 diabetes.

One of the better known categories of misfolded proteins is the prion, most notorious for its role in causing bovine spongiform encephalopathy (BSE) in cattle, commonly known as mad cow disease.

 

The prions in this disease can be passed to humans where it sometimes causes a debilitating neurological condition called variant Creutzfeldt–Jakob disease.

The prion clumps spread their talent for misfolding by seeding new clumps, causing other proteins to bend the wrong way and stick around.

Mad cow disease first caused widespread concern in the UK in the 1980s when it was recognised prions from infected nerves were spread through contaminated meat.  

A similar condition called kuru was noticed among a community in Papua New Guinea who were renowned for the practice of endocannibalism – consuming the dead within their family.

To test for prion-like mechanisms in diabetes, the researchers cultured pancreatic tissues from healthy humans and from mice that had been genetically altered to produce large amounts of human IAPP.

Adding material from older mice with type 2 diabetes, IAPP plaques formed in both sets of tissue cultures.

 

To test if these clumps could occur outside of the petri dish, the scientists injected seeds of the amyloid plaques and pancreatic material from the diabetic subjects into the transgenic mice.

In both cases plaques grew, and the mice displayed the symptoms of type 2 diabetes.

"We can induce the full-blown disease just by administering these protein aggregates," lead researcher Claudio Soto from the University of Texas told Mitch Leslie at Science.

But you shouldn't be too alarmed, because this demonstration of a communicable diabetes 'agent' doesn't exactly make it a contagious disease.

"It's not like the flu," Soto stresses.

The researchers went to great lengths to inject plaques directly into the pancreases of mice engineered to produce large amounts of IAPP, which isn't the same as demonstrating an easy transfer of infectious material between individuals.

But it is a prompt to take a fresh look at epidemiological studies hinting at type 2 diabetes spreading from mothers to children, and possibly in some blood transfusions.

The discovery also poses a new way type 2 diabetes could form and spread through the pancreas, giving hope for earlier diagnosis and new treatments.

This research was published in The Journal of Experimental Medicine.

 

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