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Cardiology |
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| 13 Oct 2009 | Viewed: 35 | |
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Scientists prevented age-Related changes in the hearts of mice and
preserved heart function by suppressing a form of the PI3K gene, in a
study reported in Circulation: Journal of the American Heart Association.
"The study provides evidence that delaying or preventing heart failure
in humans may be possible," said Tetsuo Shioi, M.D., Ph.D., senior
author of the study and assistant professor of medicine at Kyoto
University Graduate School of Medicine in Kyoto, Japan.
"Advanced age is a major risk factor for heart failure. One
reason is that aging increases the chance of exposure to cardiovascular
risk factors. However, natural changes due to aging may also compromise
the cardiovascular system."
According to the American Heart Association, 5.7 million
Americans have heart failure, and nearly 10 out of every 1,000 people
over age 65 suffer heart failure every year.
Shioi and his colleagues studied elderly mice genetically
engineered to suppress the activity of one form of the PI3K gene, which
is a part of the insulin/IGF-1signaling system that helps regulate the
lifespan of cells.
A variation of PI3K, known as the p110α isoform, plays an
important role in tissue aging. Suppressing the isoform's activity in
the roundworm C. elegans extends its life. And in fruit flies,
suppression prevents the age-dependent decline of heart function.
The Japanese researchers compared aged mice with a functional p110α to
aged mice with suppressed p110α and found that mice with the suppressed
gene had:
- improved cardiac function;
- less fibrosis (fibrosis causes the heart to lose flexibility);
- fewer biological markers of aging; and
- a pattern of cardiac gene expression like that of younger mice.
"This study showed that aging of the heart can be prevented
by modifying the function of insulin and paves the way to preventing
age-associated susceptibility to heart failure," Shioi said.
The researchers concluded that PI3K's role in cardiac aging
involved regulating other points further downstream in the
insulin/IGF-1signaling pathway, which resulted in changes in how
insulin acted in heart cells. The biological mechanism by which
suppressing the gene's activity improved the survival of the mice
remains unclear.
"The heart failure epidemic in the United States and many
other countries is due, in part, to our aging population," said Mariell
Jessup, M.D., an American Heart Association spokesperson and professor
of medicine at the University of Pennsylvania School of Medicine in
Philadelphia. "Aging humans experience a slow but gradual loss of heart
cells and a host of other cellular and sub-cellular abnormalities which
make the remaining cells contract less efficiently. Thus, this early
work in a mouse model, clarifying the role of PI3K in cardiac aging,
could ultimately allow scientists to understand if human hearts are
similarly influenced."
Co-authors are: Yasutaka Inuzuka, M.D.; Junji Okuda, M.D.;
Tsuneaki Kawashima, M.D.; Takao Kato, M.D.; Shinichiro Niizuma, M.D.;
Yodo Tamaki, M.D.; Yoshitaka Iwanaga, M.D., Ph.D.; Yuki Yoshida, M.D.,
Ph.D.; Rie Kosugi, M.D., Ph.D.; Kayo Watanabe-Maeda, M.D., Ph.D.; Yoji
Machida, M.D., Ph.D.; Shingo Tsuji, Ph.D.; Hiroyuki Aburatani, M.D.,
Ph.D.; Tohru Izumi, M.D., Ph.D.; and Toru Kita, M.D., Ph.D.
Author disclosures and funding sources are in the study.
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| News Source: medical news today |
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