What doesn't kill you makes you stronger: Cells become more efficient after going through stress by eating unwanted body tissue

  • The secret to surviving stress lies in a cell's ability to eat its own body tissue
  • The process, known as autophagy, enables us to grow stronger after mild stress
  • Stress might help us cope with age-related diseases such as Huntington's

By DAISY DUNNE FOR MAILONLINE

Published: | Updated:

Going through hard times really does make you stronger, according to new research.

Scientists have known for decades that our cells become stronger if they go through a short period of stress - but the reason for this has remained a mystery.

Now, new research suggests that the secret to surviving stress lies in our cells' ability to eat their own unwanted body tissue.

Researchers studied the tiny roundworm Caenorhabditis elegans, pictured, and found the secret to surviving stress lies in their cells' ability to eat their own body tissue

Researchers studied the tiny roundworm Caenorhabditis elegans, pictured, and found the secret to surviving stress lies in their cells' ability to eat their own body tissue

THE EXPERIMENT 

The researchers tested two groups of worms. 

One group of worms were able to undergo autophagy as normal whereas the other group had been biologically engineered to stop their self-eating abilities.

The researchers incubated the worms at 36°C, which is significantly above the temperature they are usually kept at in the laboratory, for one hour.

The heat exposure prompted the worms to feel a mild form of stress and worms from the first group started to increase their rates of autophagy.

A few days later, they exposed both groups of worms to another, longer heat shock.

The researchers found that worms that were prevented from using autophagy failed to benefit from the initial mild heat shock - whereas the worms with normal recycling abilities did benefit.

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Human cells rely on a process called autophagy - meaning self-devouring in Ancient Greek - to get rid of old, broken or unneeded molecules from the body.

Scientists at the Sanford Burnham Prebys Medical Discovery Institute (SBP) in California studied translucent worms to investigate how autophagy is linked to stress.

Dr Caroline Kumsta, who led the new study, said: 'We used C. elegans - tiny roundworms used to study fundamental biology - to test the importance of autophagy in becoming stress resistant.

'They're a great model system because they're transparent, so you can easily observe what goes on inside them, most of their genes and molecular signaling pathways have functional counterparts in humans, and they only live a few weeks, which greatly facilitate measuring their lifespans.'

As part of their experiment, the researchers tested two groups of worms.

The first group of worms were able to undergo autophagy as normal, while the other group had been biologically engineered to stop their self-eating abilities.

The researchers incubated the worms at 36°C (67°C), which is significantly above the temperature they are usually kept at in the laboratory, for one hour.

The heat exposure prompted the worms to feel a mild form of stress and worms from the first group started to increase their rates of autophagy.

A few days later, they exposed both groups of worms to another, longer heat shock.

The researchers found that worms that were prevented from using autophagy failed to benefit from the initial mild heat shock - whereas the worms with normal recycling abilities did benefit.

C. elegans, pictured, rely on a process called autophagy - meaning self-devouring in Ancient Greek - to get rid of old, broken or unneeded molecules from the body

C. elegans, pictured, rely on a process called autophagy - meaning self-devouring in Ancient Greek - to get rid of old, broken or unneeded molecules from the body

HUNTINGTON'S DISEASE

Huntington's disease was originally called Huntington's chorea (Greek for dancing) due to the involuntary movements associated with the condition.

It is an inherited disease that attacks the nerve cells in the brain. Victims can start to show symptoms at almost any age, but most will develop problems between the ages of 35 and 55.

Huntington's usually worsens over ten to 25 years. Early features include slight, uncontrollable movements of the face, jerky movements and slurred speech, which become more extreme.

Sufferers increasingly lose co-ordination and tend to find eating tiring as the throat and mouth muscles stop working properly, leading to choking and recurrent chest infections.

Hope for a treatment lies in developing medication that can slow or halt the condition by 'switching off' the faulty gene that causes the disease.

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In a second experiment, the researchers studied worms that had been given the symptoms of Huntington's disease, a fatal inherited disorder caused by proteins in the brain clumping together as the patient grows older.

The researchers discovered that a stressful heat shock early in life helped the worms cope with the symptoms of the disease later in life. 

'Our finding that brief heat exposure helps alleviate protein aggregation is exciting because it could lead to new approaches to slow the advance of neurodegenerative diseases such as Huntington's,' said Dr Hansen.

'The results may also be relevant to Alzheimer's and Parkinson's, which are similarly caused by clumping-prone proteins.'

She added that the research raises many exciting questions.

'For example, how does induction of autophagy by a mild heat stress early on make cells better able to survive heat later - what's the cellular memory? There's a lot to follow up on,' she said.

'A lot of people ask us if this means they should start going to the sauna or do hot yoga.

'That may not be an entirely bad idea - epidemiological studies do indicate that frequent sauna use is associated with longer life.

'But we have a lot more research to do to figure out whether that has anything to do with the beneficial induction of autophagy by heat stress that we see in C. elegans.'  

The researchers studied worms that had been given the symptoms of Huntington's disease, a fatal inherited disorder caused by proteins in the brain clumping together. They found that a heat shock helped the worms cope with the symptoms

The researchers studied worms that had been given the symptoms of Huntington's disease, a fatal inherited disorder caused by proteins in the brain clumping together. They found that a heat shock helped the worms cope with the symptoms

 

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