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PROTEIN FOUND TO PLAY IMPORTANT ROLE IN CELL DIVISION
MADISON, Wis. -- Looking deep into the eye of a fly, University of Wisconsin researchers have found that a single protein orchestrates two fundamental biological processes ordinarily thought to be unrelated. Not only does it command certain cells to differentiate, it also helps regulate cell division.
The finding, reported by scientists at the McArdle Laboratory for Cancer Research in the Jan. 10 issue of Science, may have important implications for understanding pancreatic and colon cancer.
The Wisconsin work focuses on DPP (decapentaplegic), a member of a powerful class of proteins called growth factors. Common to organisms as different as flies and humans, the proteins order undefined cells in the developing embryo to become organized, a process known as cell differentiation. In flies, the result is the formation of eyes, wings and legs; in humans, the end product is bone, tissues and organs.
Scientists are making significant headway using the human equivalent of DPP, known as bone morphogenic protein, to grow bones and cartilage in the laboratory. Research on fruit flies by basic scientists such as UW Medical School professor of oncology F. Michael Hoffmann, Ph.D., is helping to pave the way for such advances.
Hoffmann's group has added consistently to the growing body of knowledge on the proteins. As reported in Science, they recently found that in addition to regulating cell differentiation, DPP also synchronizes an entirely different biological process, cell division. In this multi-step cyclical process, cells make new DNA, copy it and then divide into two cells, thereby reproducing themselves.
Hoffmann and graduate student Andrea Penton concentrated on DPP's role in a sheet of cells that gives rise to the characteristic array of 700 hexagonal facets that make up the fly eye. The scientists were particularly interested in a furrow of cells that moves across the sheet like a wave, changing unpatterned cells as it rolls by into clusters of highly structured nerve cells.
"Our previous work showed that DPP is produced in the furrow and plays a role in getting cells from one stage of development to another," he said.
In a series of experiments, Penton genetically engineered cells that were unable to receive signals from DPP onto the sheet of developing eye cells. She found that DPP at the furrow was needed to synchronize cells as they entered one of the four standard steps in the cell reproduction cycle. The UW scientists speculate that DPP synchronizes cells as they are reproducing so they will be ready to differentiate into structured cells in a coordinated fashion when the signal comes.
Hoffmann said much interest surrounds mechanisms that regulate the cell cycle, since without proper regulation, cell division can fly out of control and lead potentially to cancer. Clarifying DPP's role in the process may open the door to a better understanding of human malignancies, such as pancreatic and colon cancer, which lose their ability to respond to related growth factors, he said.
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