The secret to a long life? A protein that acts as a cellular 'time machine' is found to extend the lifespan of fruit flies by 20%
- Biologists increased levels of a protein called Drp1 in the cells of fruit flies
- This was found to lengthen their life-span by between 10 and 20 per cent
- Drugs to mimic this effect in humans could increase life expectancy
- Biologists have turned back the clock on ageing in the cells of fruit flies, by increasing levels of a protein called Drp1.
This cellular time machine was found to lengthen the life-span of the insects by between 10 and 20 per cent.
Experts hope to develop drugs to mimic this effect in humans with age-related diseases including Alzheimer's, extending people's life expectancy and giving them more healthy years towards the end of their lives.
Biologists have turned back the clock on ageing in the cells of fruit flies (pictured), by increasing levels of a protein called Drp1. This cellular time machine was found to lengthen the life-span of the insects by between 10 and 20 per cent
Their approach focused on mitochondria - the tiny power generators within cells that control their growth and determine for how long they live and when they die.
Mitochondria often become damaged with age and, as people grow older, those damaged mitochondria tend to accumulate in the brain, muscles and other organs.
When cells can't eliminate the damaged mitochondria, they can become toxic and contribute to a wide range of age-related diseases.
The UCLA scientists removed the damaged mitochondria by breaking them up into smaller pieces.
When they did, the flies became more active and more energetic and had more endurance.
Following the treatment, female flies lived 20 per cent longer than their typical lifespan, while males lived 12 per cent longer on average.
David Walker, senior author of the study, said: 'It's like we took middle-aged muscle tissue and rejuvenated it to youthful muscle.
'We actually delayed age-related health decline.
'And seven days of intervention was sufficient to prolong their lives and enhance their health.'
Experts hope to develop drugs to mimic the fruit fly (pictured) effect in humans, extending people's life expectancy and giving them more healthy years towards the end of their lives
They believe that the fact that the mitochondria become larger and elongated impairs the cell's ability to clear the damaged mitochondria.
The research highlights the importance of a protein called Drp1 in ageing, levels of which decline with age in flies and mice.
To break apart the flies' mitochondria, the UCLA team increased their levels of Drp1.
This enabled the flies to discard the smaller, damaged mitochondria, leaving only healthy mitochondria. 
The team found that as fruit flies reach middle age, their mitochondria change from their original small, round shape. They believe that the fact that the mitochondria become larger and elongated impairs the cell's ability to clear the damaged mitochondria (stock image)
Drp1 levels were increased for one week starting when the flies were 30 days old.
At the same time, the flies' Atg1 gene was 'turned off', rendering the flies' cells unable to eliminate the damaged mitochondria.
This proved that Atg1 is required to reap the procedure's anti-ageing effects.
While Drp1 breaks up enlarged mitochondria, the Atg1 gene is needed to dispose of the damaged ones.
An end to Alzheimer's? Scientists show how we could block the disease in its earliest stages
- Researchers may have discovered how brain cells go bad in Alzheimer's patients
- They found bead-like structures that form and indicate the disease are caused by two proteins
- The team from UNC Medical School also said those proteins could be used to create drug targets to slow or reverse symptoms
A team of scientists at the University of North Carolina's Medical School conducted a series of experiments to look at different factors driving the disease in order to try and pinpoint a way to stop it in its tracks.
Alzheimer's disease causes abnormal deposits of amyloid beta protein and tau protein in the brain, as well as swarms of activated immune cells.
The team of researchers used different experiments to look at how the proteins and activated immune cells attack the brain and cause Alzheimer's-related symptoms.
They also found that one medicine currently in development that blocks a specific protein - HDAC6, which originates from within neurons - show progress in preventing the damage that causes those symptoms.
The drug, called tubastatin A, is currently undergoing late stage clinical trials at a number of hospitals around the United States.
Scientists at the UNC's Medical School conducted a series of experiments to look at different factors driving the disease in order to try and pinpoint a way to stop it in its tracks (stock image shows amyloid beta peptide in the brains of Alzheimer's patients)
Led by Dr Todd Cohen, assistant professor of neurology, UNC scientists used human cell cultures to show how amyloid beta can trigger a dramatic inflammatory response in immune cells and how that interaction damages neurons.
The team then showed how that kind of neuron damage leads to the formation of bead-like structures filled with abnormal tau protein.
Similar bead-like structures are known to form in the brain cells of people with Alzheimer's disease.
The UNC researchers also identified two proteins - MMP-9 and HDAC6 - that help promote this harmful, amyloid-to-inflammation-to-tau cascade.
These proteins and others associated with them could become drug targets to treat or prevent Alzheimer's.
'It's exciting that we were able to observe tau - the major Alzheimer's protein - inside these beaded structures,' said Dr Cohen, who is also a member of the UNC Neuroscience Center.
'We think that preventing these structures from forming would leave people with healthier neurons that are more resistant to Alzheimer's.'RESEARCHERS SHOWED HOW NEURONS ARE DAMAGED IN PEOPLE WITH ALZHEIMER'S
'Our thinking was that the amyloid beta oligomers would activate an inflammatory response in these immune cells, as prior research suggested, and we wanted to see if this would induce pathological forms of tau when given to neurons,' Dr Cohen said.
The researchers then focused on the fluid in which the immune cells had been growing.
This fluid, which was filled with inflammatory factors - or proteins - resembled the fluid in which these cells typically live inside human brains.
The team added this fluid to cultures of human cortical neurons. The neurons soon developed abnormal, bead-like swellings along their axons and dendrites.
Axons and dendrites are on either side of a neuron - dendrites bring information into the cell body, and axons send it out into another cell.
This 'neuritic beading' on axons and dendrites has been seen in Alzheimer's patients and has been considered an early sign of neuronal damage, although it hasn't been clear how beading was connected to abnormal tau or if the beading led to Alzheimer's disease.
The researchers then looked for tau in the beads and found a striking accumulation of it, though it was in an abnormal form and undetectable with the usual tools scientists use to detect the type of tau typically seen in Alzheimer's patients.
Instead, the beaded tau was modified in a different way than previously thought. This modification is what causes tau to become aggregated, Dr Cohen said.
Tau proteins normally provide structural support for long, railway-like structures called microtubules, which are used to transport key molecules along axons.
For reasons that have never been clear, tau proteins in Alzheimer's-affected neurons have a different pattern.
They are detached from microtubules, bear abnormal chemical modifications, and clump into long, tangled, and thread-like aggregates.
Whether these tau aggregates actively harm neurons isn't clear, but prior studies suggested that the loss of tau from microtubules and resulting disruption of axonal transport might cause serious damage.
The finding of abnormal tau in the neuritic beads indicated that these beads could mark tau's entry into the Alzheimer's disease process.
Within the beads, Dr Cohen's lab also found high calcium levels, which are known to harm neurons and are considered an important feature of neurons in people with Alzheimer's.
'We think these neuroinflammatory factors trigger this cascade,' Dr Cohen said.
'They flood the neuron with calcium. And we think that once the calcium accumulates, it causes tau to become abnormally modified.
'This probably leads to a snowball effect: tau detaches from microtubules and is trafficked throughout the neuron, ending up in these beads.
'One possibility is that these tau-filled beads are the sites where the classic tangle-like aggregates of tau will eventually emerge, which is the hallmark of Alzheimer's disease.'
A team led by collaborating researcher Dr Xian Chen, associate professor of biochemistry and biophysics at UNC, used mass spectrometry to sort out the amyloid beta-induced neuroinflammatory molecules that had triggered the calcium influx and neuritic beading.
RESEARCHERS IDENTIFIED TWO PROTEINS THAT HELP PROMOTE THE BUILDUP OF AMYLOID BETA IN THE BRAIN
'MMP-9 is an inflammatory protein shown to be elevated in the brains of Alzheimer's patients,' Dr Cohen said.
'In our study, we show that MMP-9 alone can trigger a calcium influx that floods the neuron.'
The researchers also identified the protein HDAC6, which originates from within neurons and concentrates in the neuritic beads.
Normally, HDAC6 is thought to detect unwanted protein aggregates within neurons and transport them away for disposal. However, blocking the protein stopped nearly all beads from forming in Dr Cohen's lab experiments.
Both of these proteins have been found to be elevated in affected areas of Alzheimer's brains.
Drug companies are now developing and testing HDAC6 inhibitors, which have performed surprisingly well in early studies, although it has not been fully understood how these inhibitors work.
'Our work might explain why HDAC6 inhibitors have shown such early promise,' Dr Cohen said.
'And we think our work can help inform the development of other kinds of inhibitors that affect this cascade, particularly those that might impact cognitive processes.'
A therapeutic strategy to block HDAC6 or MMP-9 might have applications beyond Alzheimer's.
Neuritic beading is seen in several other neurodegenerative diseases as well as after head injury.
Scientists have even observed beading to small extents in seemingly healthy elderly brains. Beading might be a general mechanism underlying cognitive decline, Dr Cohen said.
In their study, Dr Cohen and colleagues found some tau-filled neuritic beads in the brains of aged mice. And they discovered that chronic neuroinflammation could induce the beads to form in younger mice.
The researchers are now focused on creating a mouse model to confirm and further investigate the amyloid-to-inflammation-to tau process seen in this Cell Reports study.
'If we can demonstrate this cascade in a wild-type mouse, then we'll be able to study Alzheimer's and test therapies in ordinary lab mice without the need for artificial genetic engineering used in traditional Alzheimer's mouse models,' Cohen said.
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