help solve age-old questions
BY JAMIE TALAN
June 10, 2004
In the first genetic analysis of
the aging human brain, Harvard
scientists have identified hundreds of genes tied specifically to aging
- genes that begin to change at the ripe middle-age of 40.
finding gives new meaning to reaching 40," said Ann Graybiel, a
professor of brain science at the Massachusetts Institute of Technology
in Cambridge who was not involved in the research. "It is a heroic
effort to determine which genes are particularly vulnerable as we age."
Also of consequence is a finding of great variability in the aging
status of these genes among individuals between 40 and 70. These
age-related genes looked like those of young adults in some people in
their 50s, while others at that age had the genetic patterns of people
in their 80s, said
Dr. Bruce Yankner, lead investigator of the study,
which appears this week in the journal Nature.
professor of neurology and neuroscience at Harvard Medical School and
Children's Hospital in Boston, and his colleague, Tao Lu, collected
brain tissue from 30 unidentified people who died between ages 26 and
106. These were so-called "normal" brains, with no signs of injury or
disease. Tissue came from brain banks around the country.
According to Yankner, about 4 percent
of the 11,000 genes identified
were significantly changed over the life span and linked to the aging
frontal lobe is a uniquely human tissue that
regulates ability to carry out tasks, organize, plan, judge and analyze
information. The scientists took snippets of frontal lobe brain tissue
and placed them in lab dishes filled with thousands of gene markers,
so-called gene chip analysis. This allows scientists to identify
specific genes active at a particular time.
scientists discovered that many of the genes associated with aging play
a role in the functioning of the synapse, the gap between neurons where
communication takes place. There are billions of neurons in the human
brain. Learning and memory are tied to the strength and number of the
synapses made by these brain cells. The genes most altered by the aging
process govern several neurotransmitters that are involved with
learning and memory. Activity of these genes is significantly decreased
with advancing age,
Yankner and his colleagues found.
The good news for me is >>>>>:
found genes that did just the opposite; these genes worked harder as
the person grew older. These include
genes that repair brain proteins,
genes that repair damaged genes, and genes that protect against free
radical damage. Free radicals are toxic molecules that damage cells,
and have been the targets for prevention and treatment studies with
antioxidant compounds like vitamin E. Yankner suspects that these
increases in activity are part of a compensatory effort to protect the
brain against damage.
Yankner said variability in middle-age of
the status of these genes could begin to explain why some people seem
younger for their age, and some much older. He said the finding proves
that there are genes that are more vulnerable to damage than others.
And it seems that these age-related genes are damaged by free radical
molecules. "It does raise the possibility that this kind of damage is
reversible," Yankner said.
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