Tuesday, August 19, 2008

[StemCells] 'Vestigial' brain cilia direct neural differentiation


Yale Researchers Discover Tiny Cellular Antennae Trigger Neural Stem
Cells
Published: August 11, 2008

Tiny thread like cilia on brain cells act as sort of an antennae that
directs signals telling stem cells to create new neurons.
New Haven, Conn. — Yale University scientists today reported evidence
suggesting that the tiny cilia found on brain cells of mammals,
thought to be vestiges of a primeval past, actually play a critical
role in relaying molecular signals that spur creation of neurons in
an area of the brain involved in mood, learning and memory. The
findings are published online in the journal Proceedings of the
National Academy of Science.

The cilia found on brain cells of mammals until recently had been
viewed as a mysterious remnant of a distant evolutionary past, when
the tiny hair-like structures were used by single-celled organisms to
navigate a primordial world.

"Many neuroscientists are shocked to learn that cells in the brain
have cilia. Thus it was even more exciting to show that cilia have a
key function in regulating the birth of new neurons in the brain,"
said Matthew Sarkisian, post doctoral fellow in the department of
neurobiology and co-first author on the study.

In the past decade, scientists have discovered primary cilia may have
important functions in many animals. For instance, in 2000, Yale
University scientists discovered defects in these cilia could lead to
rare type of kidney disease. Researchers have been finding new
functions for primary cilia ever since.

In the present study, researchers discovered that in mice, primary
cilia act like antennae to receive and coordinate signals that spur
creation of new brain cells. These cilia receive signals from a key
protein required in development called "sonic hedgehog." When the
Yale team deleted genes needed to form primary cilia, they discovered
that mice developed significant brain abnormalities including
hydrocephalus. They also found that the absence of primary cilia on
neural stem cells disrupted the ability of sonic hedgehog to signal
neural stem cells to initiate creation of new neurons in the brain.

Furthermore, this group also observed cilia on dividing brain tumor
cells. Postdoctoral fellow and co-first author Joshua Breunig
said, "Considering sonic hedgehog is also heavily implicated in brain
tumor formation, our study places the primary cilium at the
crossroads of both regenerative neurobiology and neuro-oncology."

Authors include: Jon Arellano, Yury Morozov, Albert Ayoub, Sonal
Sojitra, Baolin Wang, Richard Flavell, Pasko Rakic (corresponding
author) and Terrence Town

The study was funded by the National Institutes of Health and the
Kavli Institute.

Citation: PNAS, online publication, Aug. 11

PRESS CONTACT: Bill Hathaway 203-432-1322

http://opa.yale.edu/news/article.aspx?id=5935

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StemCells subscribers may also be interested in these sites:

Children's Neurobiological Solutions
http://www.CNSfoundation.org/

Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123

The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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