Science: Death is our best friend for life: Knowledge of how cells constantly die may provide treatments for the most dangerous diseases. Ruth McKernan reports

DEATH is good for us. Not only good but also necessary. In the human body, billions of cells must die for a person to live a normal life. Scientists already know much of how cells grow and flourish. Now understanding how they die may cast light on many common illnesses from cancer to Alzheimer's disease.

The predestined death of cells in the body is a normal process. It is vital in sculpting the body during foetal development. As a hand forms, two things happen: the fingers grow, but the web of skin between them dies. To shape a human body without programmed cell death would be like trying to make a chair without a saw and sandpaper.

The same principle applies during formation of many other tissues, including skin, brain and components of the immune system. Cells must die to allow new features to evolve. In other words, death becomes us.

In the developing brain, a complex network of connections form. To ensure that cells are correctly 'wired up', double the necessary number of cells are made.

Those which do not make proper contacts die automatically. Half of our brain cells are lost in this way. If we survived without programmed cell death, we could have brains twice the size, skin inches thick and webbed feet.

Scientists believe it is preferable for cells to die in a programmed way rather than necrotically, whereby a cell 'spills its guts' and activates a series of inflammatory clean-up systems. The quick and economical removal of cells is akin to dismantling a building carefully rather than demolishing it.

Programmed cell death is important not only in development but throughout life as well. Over four to five years, virtually all the molecules in our bodies are replaced, yet we remain pretty much the same, barring perhaps a few extra wrinkles and grey hairs.

According to Gerard Evan, a senior scientist from the Imperial Cancer Research Fund (ICRF) in London, programmed cell death is largely responsible for maintaining the status quo. 'Every normal cell when it starts to divide becomes a threat to the body.'

Just one cell in which the suicide pathway has gone awry is enough to cause cancer and death of the whole animal. As a failsafe mechanism, whenever a cell is instructed to grow it will also be given the potential order to die.

It is probably better to lose functional cells than to risk keeping overactive ones. For example, a party-goer can drink to excess, lose a few irreplaceable brain cells and, provided this is not a regular event, be little the worse for it. 'For a large organism, cells are cheap - it is the whole animal that is important,' Mr Evan says.

Individual tumour cells spring up all the time but are nipped in the bud by cell death. The ICRF has found that in several tumours, a gene (c-myc) which normally promotes cell growth, is active when it should not be and seems to push the cell one step closer to being cancerous.

Other failsafe mechanisms can still trigger cell death, and it is only when there are multiple mutations that the cell will escape with its life and develop into a tumour. With greater understanding of the suicide pathway, scientists may be able to activate it in tumour cells and persuade them to self-destruct.

Martin Raff, professor of biology at University College London, believes programmed cell death does not just prevent cancer; it exists in all our cells all the time. 'Left to themselves, our cells will actively kill themselves unless continuously instructed by other cells not to do so,' he says.

The command to stay alive comes in the form of constant stimulation by growth factors and other recently discovered signalling molecules.

Several factors that can rescue nerve cells from death under laboratory conditions are undergoing clinical trials for treatment of the neuro-degeneration that underlies motor neuron disease.

As with all bodily processes, cell death is controlled by genes - so far, only a few have been identified - and rendering them inactive has serious repercussions.

One might imagine that removing a gene for cell death would make an animal live longer. Not so. Flies fail to develop at all, and the microscopic worm C. elegans lives only as long as its normal relatives, but with an extra 131 cells. Scientists know little about the genes controlling cell death in humans, but they have found one, similar to the worm gene, which means that the process is fundamentally important and conserved throughout evolution.

Two British scientists, Tom Curran and James Morgan, associate director and head of neurobiology respectively at the Roche Institute for Molecular Biology in the United States, are investigating what happens once the lethal process is switched on.

They report in Nature that they have found a gene (c-fos) which is activated in cells destined to die, the earliest event identified so far. They do not yet know whether this gene directs or merely monitors cell death, but it is active for prolonged periods whenever cell death takes place, during development of the hand or brain and, like a harbinger of death, under other circumstances too.

'It happens in all situations we've looked at: naturally, in response to an environmental toxin and after anti- cancer agents,' Dr Morgan says. While turning on cell death may be useful in controlling cancer, however, it may have dire consequences in more specialised brain or nerve cells that do not divide and cannot be replaced.

Some scientists believe that disorders in which brain cells are lost could result from problems with the suicide system. Two environmental toxins, domoic acid and kainic acid, present in algae and concentrated throughout the food chain, are neurotoxic to humans and other species. When administered to laboratory animals, Drs Curran and Morgan found that both chemicals turn on the 'grim reaper' gene and nerve cells subsequently die.

In an animal model of Parkinson's disease, where mice lost brain cells of the same type and location as in human sufferers, the Roche group found that the gene was activated only in the relevant cells.

'If we could find agents that prevent our gene switching on, these would be candidates for the treatment of Parkinson's disease,' Dr Curran says.

In principle, factors that prevent cell death or rescue dying cells may be useful in treating many degenerative diseases, including Alzheimer's. And now that there is a 'window on the process of cell death', the Roche group says that scientists can begin to seek such therapeutics.

Programmed cell death has brought scientists from different fields together. Italian scientists suspect that the agent which causes bovine spongiform encephalopathy - better known as mad cow disease and the related human Creutzfeldt-Jakob condition - can also activate the cell death programme.

Although programmed cell death has not been proved responsible for any disease, so many links have been found that there is excitement among medical researchers.

The fatal system may well turn out to be as fundamental as life itself. Contrary to Woody Allen's pessimistic dictum, it may now be possible to experience one's own death objectively, and still carry a tune.

(Photograph omitted)

Suggested Topics
News
Susan Sarandon described David Bowie as
peopleSusan Sarandon reveals more on her David Bowie romance
Sport
Arsenal supporters gather for a recent ‘fan party’ in New Jersey
football
News
i100
Sport
sportDidier Drogba returns to Chelsea on one-year deal
PROMOTED VIDEO
Arts and Entertainment
The Secret Cinema performance of Back to the Future has been cancelled again
film
Life and Style
Balmain's autumn/winter 2014 campaign, shot by Mario Sorrenti and featuring Binx Walton, Cara Delevingne, Jourdan Dunn, Ysaunny Brito, Issa Lish and Kayla Scott
fashionHow Olivier Rousteing is revitalising the house of Balmain
News
i100
Arts and Entertainment
Christian Grey cradles Ana in the Fifty Shades of Grey film
filmFifty Shades of Grey trailer provokes moral outrage in US
News
people
News
BBC broadcaster and presenter Evan Davis, who will be taking over from Jeremy Paxman on Newsnight
peopleForget Paxman - what will Evan Davis be like on Newsnight?
Life and Style
fashionCustomer complained about the visibly protruding ribs
News
ebookA unique anthology of reporting and analysis of a crucial period of history
News
newsComedy club forced to apologise as maggots eating a dead pigeon fall out of air-conditioning
Arts and Entertainment
Jo Brand says she's mellowed a lot
tvJo Brand says shows encourage people to laugh at the vulnerable
Life and Style
People may feel that they're procrastinating by watching TV in the evening
life
News
Tovey says of homeless charity the Pillion Trust : 'If it weren't for them and the park attendant I wouldn't be here today.'
people
Sport
Rhys Williams
commonwealth games
Independent
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
santorini
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Employment Solicitor

Highly Competitive Salary: Austen Lloyd: MANCHESTER - Senior Employment Solici...

Senior Risk Manager - Banking - London - £650

£600 - £650 per day: Orgtel: Conduct Risk Liaison Manager - Banking - London -...

Commercial Litigation Associate

Highly Attractive Package: Austen Lloyd: CITY - COMMERCIAL LITIGATION - GLOBAL...

Systems Manager - Dynamics AX

£65000 - £75000 per annum + Benefits: Progressive Recruitment: The client is a...

Day In a Page

Evan Davis: The BBC’s wolf in sheep’s clothing to take over at Newsnight

The BBC’s wolf in sheep’s clothing

What will Evan Davis be like on Newsnight?
Finding the names for America’s shame: What happens to the immigrants crossing the US-Mexico border without documents who never make it past the Arizona desert?

Finding the names for America’s shame

The immigrants crossing the US-Mexico border without documents who never make it past the Arizona desert
Inside a church for Born Again Christians: Speaking to God in a Manchester multiplex

Inside a church for Born Again Christians

As Britain's Anglican church struggles to establish its modern identity, one branch of Christianity is booming
Rihanna, Kim Kardashian and me: How Olivier Rousteing is revitalising the house of Balmain

Olivier Rousteing is revitalising the house of Balmain

Parisian couturier Pierre Balmain made his name dressing the mid-century jet set. Today, Olivier Rousteing – heir to the house Pierre built – is celebrating their 21st-century equivalents. The result? Nothing short of Balmania
Cancer, cardiac arrest, HIV and homelessness - and he's only 39

Incredible survival story of David Tovey

Tovey went from cooking for the Queen to rifling through bins for his supper. His is a startling story of endurance against the odds – and of a social safety net failing at every turn
Backhanders, bribery and abuses of power have soared in China as economy surges

Bribery and abuses of power soar in China

The bribery is fuelled by the surge in China's economy but the rules of corruption are subtle and unspoken, finds Evan Osnos, as he learns the dark arts from a master
Commonwealth Games 2014: Highland terriers stole the show at the opening ceremony

Highland terriers steal the show at opening ceremony

Gillian Orr explores why a dog loved by film stars and presidents is finally having its day
German art world rocked as artists use renowned fat sculpture to distil schnapps

Brewing the fat from artwork angers widow of sculptor

Part of Joseph Beuys' 1982 sculpture 'Fettecke' used to distil schnapps
BBC's The Secret History of Our Streets reveals a fascinating window into Britain's past

BBC takes viewers back down memory lane

The Secret History of Our Streets, which returns with three films looking at Scottish streets, is the inverse of Benefits Street - delivering warmth instead of cynicism
Joe, film review: Nicolas Cage delivers an astonishing performance in low budget drama

Nicolas Cage shines in low-budget drama Joe

Cage plays an ex-con in David Gordon Green's independent drama, which has been adapted from a novel by Larry Brown
How to make your own gourmet ice lollies, granitas, slushy cocktails and frozen yoghurt

Make your own ice lollies and frozen yoghurt

Think outside the cool box for this summer's tempting frozen treats
Ford Fiesta is UK's most popular car of all-time, with sales topping 4.1 million since 1976

Fiesta is UK's most popular car of all-time

Sales have topped 4.1 million since 1976. To celebrate this milestone, four Independent writers recall their Fiestas with pride
10 best reed diffusers

Heaven scent: 10 best reed diffusers

Keep your rooms smelling summery and fresh with one of these subtle but distinctive home fragrances that’ll last you months
Commonwealth Games 2014: Female boxers set to compete for first time

Female boxers set to compete at Commonwealth Games for first time

There’s no favourites and with no headguards anything could happen
Five things we’ve learned so far about Manchester United under Louis van Gaal

Five things we’ve learned so far about United under Van Gaal

It’s impossible to avoid the impression that the Dutch manager is playing to the gallery a little