Biologists at the University of California, San Diego have found that two genes associated with the development of human cancer play a central role in orienting a cell's "internal compass," guiding white blood cells with missile-like precision to the sites of infections and leading other types of cells directly to nutrients and a myriad of other important chemical cues.

Their discovery, detailed in a paper in the May 31 issue of the journal Cell, sheds light on the long-standing mystery of how cells are able to steer directly toward the source of chemical attractants, a process biologists call "chemotaxis."

"Many cells within our body are able to sense chemical signals over long distances and move to the source of these signals," says Richard A. Firtel, a professor of biology and director of the Center for Molecular Genetics at UCSD. "For example, when a wound becomes infected, white blood cells rush to the site of the wound in the body's first major response to fighting the infection. The white blood cells are able to sense the bacteria because the bacteria release small molecules that are recognized by proteins on the surface of the white blood cell. Similarly, breast cancer cells can migrate out of the tumor in the direction of blood vessels, leading to metastasis and secondary sites of tumor formation."

Scientists have learned much about the chemical cues that elicit these responses in cells. But until now, the mechanisms cells use to steer themselves to these attractants had been poorly understood.

Firtel and his colleagues-UCSD postdoctoral researchers Satoru Funamoto and Reudi Meili; Susan Lee, a research associate; and Lisa Parry, an undergraduate student-elucidated how this internal directional compass in cells works by studying Dictyostelium discoideum, a simple social amoeba and model genetic system that exhibits many of the properties of white blood cells. The scientists first determined that chemotaxis in Dictyostel
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Contact: Richard A. Firtel
rafirtel@ucsd.edu
619-300-3366
University of California - San Diego
30-May-2002