From: Gina Miller (echoz@hotmail.com)
Date: Fri Apr 23 1999 - 14:01:39 MDT
Study Discloses New Component of Cells' Built-In Suicide Program;
Research Finding Opens Uncharted Area of Cell Life/Death
BUSINESS WIRE
Company Multilink
• Howard Hughes Medical Institute
BOSTON--(BW HealthWire)--April 22, 1999--Scientists at Dana-Farber
Cancer Institute and Duke University Medical Center have uncovered a
new portion of the circuitry that controls the natural death of cells
-- a malfunction of which may underlie diseases ranging from cancer
to heart disease to autoimmune disorders.
The study, published in the April 23 issue of Science, not only opens
a previously uncharted area of cell life to scientific study, but
also identifies new targets for therapies that can return diseased
cells to the normal path of mortality.
"This research elucidates how cells naturally commit suicide, or
undergo 'apoptosis,'" says Joan Mannick, M.D., of Dana-Farber, who co-
authored the study with Jonathan Stamler, M.D., a [ Howard Hughes
Medical Institute ] researcher at Duke. "We now know that in addition
to the controls on apoptosis that have already been identified,
there's another control system that works in unison with them."
The study focuses on a protein called caspase which is an essential
component of cells' suicide machinery.
In the laboratory, chemical bundles of nitric oxide (NO) can be made
to attach to, or become detached from, caspase. This coupling and
decoupling can have a powerful effect on a protein's activity. When
caspase proteins are bound to NO, they're essentially handcuffed from
performing their normal function. When the NO is removed, cell death
can proceed.
But whether such binding and unbinding occurs in living cells -- and
what it would mean if it does -- has been unclear. In fact, only a
few types of proteins have been found to be attached to NO in cells.
The current study involved human lymphocytes, white blood cells that
help provide immune protection against disease. Such cells perform a
variety of functions, but one thing they don't do is produce much NO.
Mannick and her colleagues extracted caspase from lymphocytes that
were in a "resting" state -- that is, not yet embarked on apoptosis.
To their surprise, they found the protein had an NO group attached.
"The fact that we found NO attached to proteins even in cells that
produce very little of it indicates that NO may help regulate protein
function in a much broader range of cells than was previously
appreciated," Mannick says.
The nature of its role became clear when researchers triggered the
cells' apoptosis mechanism. The caspase proteins collected from the
apoptotic cells had lost their NO.
"This is the first time that NO has been found to attach and detach
from caspase in living cells," Mannick says. "It represents a new
control mechanism for cell death, and potentially, a new mechanism
for controlling other cell functions."
Researchers were able to detect the presence or absence of NO thanks
to technology developed by Stamler and his colleagues at Duke. The
Duke team has developed new techniques which make it possible to find
minute amounts of NO within cells.
Previous work by the Stamler lab has shown that NO represents a key
on-off switch for a variety of cell functions. "The new study
confirms that apoptosis is one of them," Stamler says.
Besides demonstrating that the control system for apoptosis has a
previously unknown layer of complexity, the new study may offer new
prospects for therapy.
"Defects in apoptosis contribute not only to cancer, in which cells
are blocked from committing suicide, but also in conditions such as
stroke and neurodegenerative diseases, in which cells die too
readily," Stamler says. "Knowing more about the systems that controls
apoptosis provides new opportunities for therapies aimed at
correcting the system when it goes awry."
(Copyright 1999)
_____via IntellX_____
Publication Date: April 22, 1999
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Gina "Nanogirl" Miller
Nanotechnology Industries
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