[Editors] MIT IDs proteins key to brain function

[Elizabeth Thomson]

MIT News Office
Massachusetts Institute of Technology
Room 11-400
77 Massachusetts Avenue
Cambridge, MA  02139-4307
Phone: 617-253-2700
http://web.mit.edu/newsoffice/www

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MIT IDs proteins key to brain function

--Research could lead to new treatments for brain injuries

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For Immediate Release
TUESDAY, NOV. 20, 2007
Contact: Elizabeth A. Thomson, MIT News Office -- Phone: 617-258-5402  
-- Email: thomson at mit.edu

PHOTO, VIDEO AVAILABLE

CAMBRIDGE, MA- MIT researchers have identified a family of proteins  
key to the formation of the communication networks critical for  
normal brain function. Their research could lead to new treatments  
for brain injury and disease.

The team, led by MIT biology professor Frank Gertler, found that a  
certain family of proteins is necessary to direct the formation of  
axons and dendrites, the cellular extensions that facilitate  
communication between neurons.

The work focuses on cellular outgrowths called neurites, which are  
the precursors to axons and dendrites. Understanding how neurites  
form could eventually lead to therapies involving stimulation of  
neurite growth, said Gertler.

“You could use these insights to help repair injuries to the top of  
the spinal column, or treat brain injuries or neurodegenerative  
disorders,” he said.

The researchers developed the first model that allows for study of  
the effects of this protein family, known as the Ena/VASP proteins.  
The team reported aspects of their work in the Nov. 11 issue of  
Neuron and the Nov. 18 online edition of Nature Cell Biology.

The majority of neurons in the cerebral cortex have a single axon-a  
long, thin extension that relays information to other cells-and many  
shorter dendrites, which receive messages from other cells. The  
interconnection of these axons and dendrites is essential to create a  
functional neural circuit.

In their study, the researchers found that mice without the three Ena/ 
VASP proteins did produce brain cells, but those neurons were unable  
to extend any axons or dendrites.

It was already known that Ena/VASP proteins are involved in axon  
navigation, but the researchers were surprised to find that they are  
also critical for neurite formation, Gertler said.

Ena/VASP proteins are located in the tips of a neurite's filopodia,  
which are short extensions that receive environmental signals and  
translate them into instructions for the cell. Those instructions  
tell the cell whether to continue extending the filopodia by  
lengthening actin protein filaments, or to stop growth.

Without the Ena/VASP proteins, neurites cannot form, and no  
connections are made between neurons.

The researchers believe that Ena/VASP proteins control the growth of  
filopodia by regulating actin filaments' interactions with  
microtubules in the cell (which form part of the cell skeleton). One  
theory is that the microtubules might be delivering materials or  
sending signals to the filopodia through the actin filaments, Gertler  
said.

Lead authors of the Neuron paper are Adam Kwiatkowski, an MIT Ph.D.  
recipient, and graduate student Douglas Rubinson. Lead author of the  
Nature Cell Biology paper is former MIT postdoctoral fellow Erik Dent.

The research was funded by the National Institutes of Health and the  
Stanley Center for Psychiatric Research at the Broad Institute of MIT  
and Harvard.

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Written by Anne Trafton, MIT News Office