( Scientists at Duke University Medical C...)Living view in animals shows how cells decide to make proteins

The scientists say the findings, made in mice, help explain a key wonder of human biology: how the same genes found in every cell of an individual’s body can produce different proteins in different tissues and organs. These varied proteins, in turn, dictate the function of each tissue or organ.

The findings also may offer insight into a number of diseases, including cancer, in which the genetic process -- called alternative splicing -- goes awry and produces the wrong proteins, the scientists said.

The scientists published the findings in the Dec. 1, 2006, issue of the journal RNA. The study was funded by the National Institutes of Health.

Scientists previously have examined alternative splicing in cells and tissues in test tubes, but this study marks its first successful visualization in a living mammal, said senior investigator Mariano Garcia-Blanco, M.D., Ph.D., a professor of molecular genetics and microbiology.

"We were able to watch alternative splicing as it occurred in different tissues," he said. "It’s an excellent example of how experiments in living organisms provide a much more complete picture of how genes and proteins behave than do experiments using cells in culture."

Until 20 years ago, scientists believed that a single gene made a single protein. With the discovery of alternative splicing, it became clear that one gene can produce multiple proteins.

In alternative splicing, microscopic "scissors" in a gene chop the genetic material RNA into bits called "exons" and then reassemble the bits in a different order to form a new RNA molecule. In the process, some of the exons are retained while others are excluded. The exons that are retained in the final RNA determine which proteins the RNA pr
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Source:Duke University Medical Center