Researchers solve piece of large-scale gene silenci...(viable therapeutic approach for cancer p...)

"Dr. Pikaard's study demonstrates the potential of a plant model system to yield important molecular details on how cells silence large clusters of genes," said Anthony Carter, Ph.D., who oversees gene regulation grants at the National Institutes of Health's National Institute of General Medical Sciences, which partially supported the research. "His findings on the control of a major class of RNA found in all cells offer new insights into gene silencing mechanisms."

Pikaard and his collaborators' work, which was published in Molecular Cell on Dec. 4, is also one of the first to demonstrate how siRNAs can play a role in controlling the dosage of vital genes. The research was supported by the National Institutes of Health and the National Science Foundation.

Nucleolar dominance is considered an "epigenetic" phenomenon. Epigenetics refers to heritable changes in gene expression that arise from changes in the "packaging" of DNA rather than modification of the underlying DNA sequence itself. Because these changes do not follow the normal rules of genetics, Pikaard refers to them as the "X-files of biology," unusual events that are not easily explained nor predicted.

Although biologists have been studying nucleolar dominance since the 1920s, this phenomenon remained largely unresolved until recently, when Pikaard's lab reversed an old dogma. Up until this point, researchers had presumed that nucleolar dominance was all about turning on one set of parental ribosomal genes. In 1997, Pikaard and his colleagues made headlines with an experiment that used chemicals to inhibit the two-pronged method cells employ to silence genes
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