Cell movements totally modular, Stanford s...( STANFORD Calif. A study describing ...)

STANFORD, Calif. A study describing how cells within blood vessel walls move en masse overturns an assumption common in the age of genomics that the proteins driving cell behavior are doing so much multitasking that it would be near impossible to group them according to a few discrete functions.

But now researchers at the Stanford University School of Medicine have shown that distinct groups of proteins each control one of four simple activities involved in the cells' collective migration. The findings will be published in the Dec. 1 issue of Genes and Development.

Graduate student Philip Vitorino, the study's first author, began the project in 2004 in the laboratory of senior author Tobias Meyer, PhD, professor of chemical and systems biology. The work is part of the Meyer lab's larger effort to find order in the overwhelming complexity of the inner workings of cells.

First they grew the cells (originally from umbilical cord tissue) into sheets and watched what happened when they scratched some of the cells away: They were looking to see the movements of individual cells and overall sheet movements as cells filled the open space.

"We stained the nuclei and took a movie under a microscope and watched what they did over a 15- to 20-hour period," said Vitorino. "That's when we noticed the cells moving inside the sheet, even in the absence of an open space. Not only were they moving, but they were moving in a flow-like pattern with neighboring cells moving as small collective groups. It looked like these groups were moving on invisible paths."

The cells moved at a rate of 10 microns an hour, pretty sprightly for a cell, Vitorino said. The researchers found they could break down movement into four processes: single cell movements, coordination of neighboring cells, directional sensing and cell division.

Vitorino went on to inactivate the more than 100 genes suspected of playing a role in controlling m
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