( An organelle called the nucleolus resid...)Regulating the nuclear architecture of the cell

Gary Karpen and Jamy Peng, researchers in the Life Sciences Division of the Department of Energy's Lawrence Berkeley National Laboratory, have now discovered two pathways that regulate the organization of the nucleolus and other features of nuclear architecture, maintaining genome stability in the fruit fly Drosophila melanogaster. Their results are published in Nature Cell Biology and are now available online to subscribers.

Because much of the genome of Drosophila is shared with human beings, learning how nuclear organization is controlled in the fruit fly can apply to human disorders like birth defects and cancer. The organization of structures in the cell's nucleus has profound effects on such essential functions as how and when genes are expressed. When regulation fails, genome aberrations accumulate, including repeated sequences of DNA or even entire extra chromosomes.

"Our project continues to point to an understanding of genome stability in humans," says Karpen, who heads Berkeley Lab's Department of Genome and Computational Biology. Karpen is also codirector of the Drosophila Genome Center (sponsored by the National Human Genome Research Institute, the National Cancer Institute, and the Department of Energy) and an adjunct professor of molecular and cell biology at the University of California at Berkeley.

The epigenetics of heterochromatin

Controlling functions of the cell and organism through nuclear architecture and spatial rearrangements is known as epigenetics from the Greek for "on, over, or at" the genes, instead of by the DNA sequence. The chromosomal material known as heterochromatin mediates gene silencing, chromo
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Source:DOE/Lawrence Berkeley National Laboratory