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| Heidelberg, 25 August 2006 |
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| A switch between life and death
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Researchers discover how a signal tells cells whether to grow or die
Press
Release 25 August 2006 [PDF]
Cells in an embryo divide
at an amazing rate to build a whole body, but this
growth needs to be controlled. Otherwise the result may
be defects in embryonic development or cancer in
adults. Controlling growth requires that some cells
divide while others die; their fates are determined by signals
that are passed from molecule to molecule within
the cell. Researchers at the European Molecular Biology
Laboratory [EMBL] in Heidelberg have now discovered
how one of these signaling pathways controls the life
and death of cells in the fruit fly. The study will be published
in this week's issue of the journal Cell.
The breakthrough came as Barry Thompson from
Stephen Cohen's group at EMBL looked at a recently
discovered signaling pathway called Hippo.
"Hippo acts as a switch between cell division and death,"
says Barry Thompson, "if the pathway is too active, tissues
overgrow because too many cells divide and too few
die. But until now, we hadn't found a connection
between the signals and the cellular machinery that
drives growth."
Using sophisticated genetic techniques, Thompson and
Cohen established that a small molecule, a microRNA
called bantam, makes this link. Without bantam, tissues
grow too slowly and remain smaller than normal. The
amount of bantam produced by the cell directly depends
on the amount of traffic on the Hippo signaling pathway,
and higher levels of bantam prompt more cell division.
"bantam is an unusual type of RNA molecule,"
Thompson says. "Normally, RNAs go on to make protein,
but bantam is different. Its job is to regulate other
RNAs by attaching itself to them; the result is that they
block their expression into proteins. In this case, those
proteins would go on to shut down cell division. With
bantam around, the brake is off, and they continue to
divide."
Cohen and his lab have been studying microRNAs like
bantam for some time because of their important role in
the regulation of many vital processes across species.
The next step will be to identify the RNAs that bantam docks onto to control. This will provide a more complete
view of the Hippo pathway and may provide
insights into the central role it plays in tissue growth and
cancers in humans and other organisms.
Source Article
B.J. Thompson & S.M. Cohen. The Hippo pathway regulates the bantam microRNA to control cell proliferation and apoptosis
in Drosophila, Cell, 25 August 2006
Press Contact
Anna-Lynn Wegener
Press Officer
EMBL Heidelberg
Tel: +49 +6221 387-8452
Email: wegener@embl.de |
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