Extending health span with genetics
Fruit fly find suggests approaches for keeping youthful vigor
By Charlene Laino
MSNBC
June 1 —Canadian scientists reported Monday that they have successfully
extended the life span of the fruit fly by inserting into its DNA a designer
gene that prevented some of the cellular damage normally associated with
aging. The approach holds potential for increasing humans’ health span —
“our days of youthful vigor,” said researcher John Phillips of the
University of Guelph.
USING GENETIC ENGINEERING techniques, an extra gene was inserted into the
fruit fly’s motor neurons — nerve cells that control movement — boosting
their ability to remove toxins from the body and extending their life span
by 40 percent.
While an extra 30 days added to the normal 80-day life span of a
fruit fly might sound insignificant, the find has enormous implications for
biology, Phillips said.
“We have discovered that [weakening of the detoxifying mechanism] in
motor neurons is the Achilles heel of life span,” the Canadian scientist
said.
Drug companies are already working on new pharmaceuticals targeted at
the motor neurons that would work to increase our health span, he noted.
But perhaps even more importantly, the findings mark the first time
researchers have shown that a single gene in a single type of cell can
affect longevity.
“We were really surprised,” said study head Gabrielle Boulianne, a
neurobiologist at the Hospital for Sick Children and a professor of
molecular and medical genetics at the University of Toronto. “We now know
that just manipulating just one gene, targeting one type of cell, has a huge
impact on aging.
“Contrary to what was previously thought — that many different
factors contribute to aging — it now appears that the process may be
simpler,” Boulianne said.
The study is published in the June issue of the journal Nature
Genetics.
The new research grew out of work showing that the efficiency with
which organisms use oxygen directly correlates to their life span, Phillips
said. Humans, who have the longest lives of any organism, are the most
efficient users of oxygen, for example, while mice and hummingbirds, who
have relatively short lives, are inefficient users.
The reason, he said, is that oxygen is very toxic. “Even at the 21
percent atmospheric oxygen that we breathe, there has evolved a detoxifying
mechanism without which we would all keel over and die,” Phillips explained.
Over the past decade, scientists have identified the genes
responsible for this detoxifying mechanism. When this gene is made inactive
via a human-made mutation in the fruit fly, Phillips said, its life span is
reduced by some 80 percent to 90 percent.
At about the same time, researchers came to better understand that
motor neurons are somehow associated with this detoxifying mechanism.
Studies have shown that people with Lou Gehrig’s disease, a paralytic
disorder that is caused by a loss of motor neurons, tend to have family
members whose genes controlling oxygen detoxification are faulty, for
example.
Moreover, in species ranging fruit flies to humans, there is evidence
that loss of motor neuron function is a prominent feature of disease, aging
and death, molecular biologist Phillips said. “We theorized that motor
neurons might be at the nexus of aging and oxygen metabolism.”
That research led to the question: What would happen if we upgraded
that detoxification defense mechanism? Would the organism live longer?
To answer the question, the team created a designer gene that would
enhance oxygen detoxification in motor neurons.
The human-made gene was then added to the fruit fly’s normal genetic
makeup.
The experiment worked. Not only did the gene help the motor neurons
eliminate more waste, but the fruit flies they lived longer.
Drug companies are already working on new antioxidant formulas
targeted at the motor neurons that work more efficiently in the nervous
system to rid our bodies of toxins and increase our health span, Phillips
said.
While some theorize that the approach could be used to create a pill
that would let us all live 40 percent longer — boosting average age from 80
to 110 — Phillips said that is not his intention. “There are too many social
implications,” he said. “Already there are problems with old-age pensions,
for example.”
Rather, the find can be used to help us live healthier, avoiding the
sickness and disease normally associated with old age, he said.
“The way in which the approach extended the life span of the fruit
fly is encouraging,” Phillips said. “Life span was extended though
postponement of the onset of senescence.”
In other words, he said, we could live our final days not in a
geriatric ward, but full of youthful energy.