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Nerve cells are 'ultrafast' recyclers, Utah study finds

Published December 5, 2013 7:33 am

University of Utah • New, quicker process for recycling "communication bubbles" between nerve cells discovered.
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New research at the University of Utah indicates a key part of the communication between nerve cells can happen much faster than previously thought.

The discovery could one day help treat degenerative diseases such as Lou Gehrig's and Alzheimer's.

Researchers examined how cells recycle tiny, bubble-like vesicles that move neurotransmitters between synapses. Vesicles are formed in cell nuclei, and after they deliver their cargo, they melt back into the cell's outer plasma membrane, a little like a soup bubble releasing steam and popping.

The process happens hundreds of times per second, and it's how the brain gets messages like, the stove is hot! or move your finger now!

Vesicles are a hot topic in neuroscience — other research on how they're formed and function won a Nobel prize this year.

In the new study published Wednesday in the journal Nature, U. scientists and German biologists studied how vesicles are recycled to make new ones. The researchers found the process can happen in one-tenth of a second — much faster than previous hypotheses of 1 to 20 seconds.

"If you are sending vesicles formed in the nuclei to the synapse, every time you use one it takes forever, so you have to locally regenerate the vesicles," said Shigeki Watanabe, a postdoctoral fellow in biology and first author on the paper.

The process is called ultrafast endocytosis. U. biology professor and senior author Erik Jorgensen says it's a little like Whac-a-Mole.

"One vesicle goes down (fuses and unloads) and another pops up someplace else," he said in a statement.

Each cell has a supply of 300 to 400 of these little messengers at any one time. They're used and recycled so fast that a single cell can use several hundred per second.

"Without recycling these containers ... you could move once and stop, think one thought and stop, take one step and stop, and speak one word and stop," Jorgensen said.

The researchers set up a unique method to study the process. They bred mice with an algae gene that caused their brain cells to fire up when exposed to light. Researchers removed some of those cells, cultured them and then flash-froze the cells with a blast of liquid nitrogen in the act of turning on.

"We found a way to look at this process on a time­scale that no one ever looked at before," Watanabe said in a statement. The researchers studied the frozen neurons under an electron microscope.

The scientists will now look at how often the cells use ultrafast endocytosis — Jorgensen believes it's more common than previously identified methods, called kiss-and-run endocytosis and clathrin-mediated endocytosis.

The new method may also help protect neurons from disease, so understanding it better could also help treat neurodegenerative disorders.

lwhitehurst@sltrib.com

Twitter: @lwhitehurst