Nerve Signals Kept In Check By Friend Protein

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Nerve Signals Kept In Check By " Friend " Protein

http://www.medicalnewstoday.com/medicalnews.php?newsid=47993

Among the many thousands of proteins in the cell, some are essential

players while some are " hangers-on. " The neuronal protein syntaxin is

essential. Without it, you die. A more recently discovered protein

called tomosyn hangs on, or binds, to syntaxin. Its Japanese

discoverers named it tomosyn by combining tomo -- " friend " in

Japanese -- with " syn " for syntaxin, to mean " friend of syntaxin. "

Now a U.S.-based research team reports this friendly protein appears

to play a key role in regulating the synaptic release of

neurotransmitter chemicals, which suggests that it may also play a

role in learning and memory.

Better understanding of the neurological function of this protein may

lead to a better understanding of how synapses get stronger or

weaker, and how that, in turn, affects memory formation and loss,

says Janet Richmond, associate professor of biological sciences at

the University of Illinois at Chicago.

" It's amazing we remember things from as far back as our early

childhood with the constant protein turnover going on in our brains, "

said Richmond. " So understanding how proteins function to control

synaptic strength is really important. "

Richmond and her colleagues used the soil nematode worm

Caenorhabditis elegans to study the function of tomosyn using a

recording technique she developed to understand how synaptic proteins

affect release of neurotransmitters at the nerve cell junctions. The

lab's ability to study synaptic transmission was recently improved

with the addition of high pressure freeze electron microscopy and

immuno-gold staining, which together provide a clearer picture of

where neurotransmitter-containing synaptic vesicles and proteins

cluster.

Mutant worms lacking tomosyn were compared to normal worms to

determine what effect, if any, the protein had on neuronal

transmission. The observed effect is substantial -- the protein helps

put a limit on the number of synaptic vesicles that become competent

to fuse at synapses, thereby regulating the amount of

neurotransmitter released.

" If you remove tomosyn, you get exuberant neurotransmitter release, "

said Richmond. " This suggests tomosyn is a negative regulator of

release. In other words, it dampens down the system, regulating the

efficiency and strength of the synapse. "

Because the nematode C. elegans uses proteins in its nervous system

comparable to those in humans, Richmond suspects that forthcoming

experiments involving tomosyn in mammals such as laboratory mice will

show similar results.

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The findings were reported online July 24 in PLoS Biology, the Public

Library of Science. Funding was provided by the National Institutes

of Health.

Co-authors of the paper include Elena Gracheva, Burdina, e

Berthelot-Grosjean and Ackley of UIC, Robby Weimer of Cold

Stream Harbor Laboratory, Holgado of Loyola University

Chicago, and Gayla Hadwiger and Nonet of Washington

University in St. Louis.