Scientists identify a molecule that coordinates the movemen...( Even cells commute. To get from thei...)

Even cells commute. To get from their birthplace to their work site, they sequentially attach to and detach from an elaborate track of exceptionally strong proteins known as the extracellular matrix. Now, in research to appear in the October 3 issue of Cell, scientists at the Howard Hughes Medical Institute and Rockefeller University show that a molecule, called ACF7, helps regulate and power this movement from the inside - findings that could have implications for understanding how cancer cells metastasize.

"The most dangerous part of cancer is that cancer cells migrate from their primary location and invade other parts of the body," says first author Xiaoyang Wu, a postdoc in Elaine Fuchs's Laboratory of Mammalian Cell Biology and Development. "ACF7 facilitates cell movement, so it's possible that the less ACF7 a cell has, the less malignant it would become. It's a really exciting question in cancer biology now."

To travel along the extracellular matrix, cells must stick to and unstick from it via focal adhesions, structures composed of molecules that connect the inside to the outside of the cell. (While some molecules connect to the matrix, others connect to a scaffold inside the cell called the cytoskeleton.) As these structures collectively assemble and disassemble, the cell walks forward. Fuchs and Wu show that ACF7 can not only access energy stores to power this movement from within but also coordinate it by linking two fiber-like proteins called f-actin and microtubules, which together form the cytoskeleton and help give cells their shape.

"Inside the cell, actin cables converge at focal adhesions at the cell's leading edge," Fuchs explains. "We found that ACF7 guides microtubules along a roadway of actin cables and leads them toward the focal adhesions at the cell's periphery. Among the cargo transported along microtubules are factors that disassemble focal adhesions. Hence by coupling microtubule, actin and focal adh
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