Biomedical Beat - A monthly digest of research news from NIGMS

August 15, 2006

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The National Institute of General Medical Sciences (NIGMS), one of the National Institutes of Health, supports all research featured in this digest. Although only the lead scientists are named, coworkers and other collaborators also contributed to the findings. To read additional news items, visit NIGMS News.

Cool Image: The Cellular Metropolis

Courtesy of Kathryn Howell, a cell biologist at the University of Colorado Health Sciences Center.
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Like a major city, a cell teems with specialized workers that carry out its daily operations—making energy, moving proteins, or helping with other tasks. Researchers took microscopic pictures of thin layers of a cell and then combined them to make this 3-D image featuring color-coded organelles—the cell’s “workers.” Using this image, scientists can understand how these specialized components fit together in the cell's packed inner world. Courtesy of Kathryn Howell, a cell biologist at the University of Colorado Health Sciences Center.

Howell lab home page

FDA Approves HIV Drug for Resistant Infections

Structure of darunavir bound to HIV protease. Courtesy of Ghosh.
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Caption: Structure of darunavir bound to HIV protease. Courtesy of Ghosh.

The U.S. Food and Drug Administration has approved Prezista (darunavir), the first antiviral drug designed to treat drug-resistant strains of HIV. The drug is a molecule designed by Arun Ghosh, a synthetic organic chemist now at Purdue University. Ghosh created the molecule based on the structure of HIV protease, an enzyme that enables the virus to reproduce and the target of many existing therapies. Ghosh's molecule blocks the enzyme's activity by binding to its backbone. This region is less likely to change as the virus evolves, reducing the likelihood that the virus will become resistant to the new drug. The drug enhances the current approach for treating HIV infection and may be available to patients this year.

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Ghosh lab home page

High Weight Doesn’t Always Equal High Fat

What’s the skinny on fat? Size matters. A team of researchers led by statistical geneticist Gary Churchill of the Jackson Laboratory studied the genetic networks that influence body size and body fat in mice. The scientists found that the two networks can act independently, suggesting that a high weight doesn’t necessarily equal a high percentage of body fat. If the findings hold up in humans, they may point to the value of calculating obesity not just by weight and height, but also by body size. Churchill leads the Jackson Center for Genome Dynamics, a new NIGMS-supported systems biology center that uses experimental and computational approaches to understand how our genes interact to keep us healthy or make us sick.

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Center for Genome Dynamics home page
NIGMS Systems Biology home page
Article abstract (from the July 2006 issue of PLoS Genetics)

Spider Venom Opens Door to New Drugs

Brown recluse spider. Courtesy of John S. Williams.

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Caption: Brown recluse spider. Courtesy of John S. Williams.

Ion channels are like carefully controlled doors into cells. By selectively allowing charged molecules called ions to pass, the channels generate electrical signals key to neuronal and muscular function. Some channels require a special molecular key to open, while others respond to electrical jolts. With an enzyme from the venom of the brown recluse spider, physiologist Zhe Lu of the University of Pennsylvania forced open a type of ion channel previously known only to respond to an electrical trigger. Because ion channels are involved in a host of biological processes, the work may pave the way for new drugs that target the channels.

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Lu home page
Article abstract (from the June 21, 2006, issue of Nature)

Metabolic Enzyme Moonlights in Gene Expression

Most enzymes involved in energy metabolism stick to the job of breaking down complex molecules into smaller molecular building blocks and energy. Not so for one cog in this intricate process. A study led by molecular biologist Jef Boeke of Johns Hopkins University revealed that the enzyme Acs2p also plays a key role in gene regulation—loss of Acs2p leads yeast cells to turn off 70 percent of their genes and die. According to the study, this sweeping effect on gene activity results from the accompanying loss of Acs2p’s product, acetyl-CoA, which is involved in a global gene activation process known as histone acetylation. These findings could lead to new ways to slow cellular aging, which has been linked to energy metabolism and histone acetylation in yeast and other organisms.

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Boeke lab home page
Article abstract (from the July 21, 2006, issue of Molecular Cell)