Toxic chemicals wreak havoc on cells, damaging DNA and other critical molecules. A new study from researchers at MIT and the University at Albany reveals how a molecular emergency-response system shifts the cell into damage-control mode and helps it survive such attacks by rapidly producing proteins that counteract（抵消） the harm. Peter Dedon, a professor of biological engineering at MIT, and colleagues had previously shown that cells treated with poisons such as arsenic（砒霜） alter their chemical modification of molecules known as transfer RNA (tRNA), which deliver protein building blocks within a cell. In their new paper, appearing in the July 3 issue of Nature Communications, the research team delved into how these modifications help cells survive.

The researchers found that toxic stresses reprogram the tRNA modifications to turn on a system that diverts the cell's protein-building machinery away from its routine activities to emergency action. "In the end, a stepwise mechanism leads to selective expression of proteins that you need to survive," says Dedon, senior author of the Nature Communications paper.

The findings offer insight into not only cells' response to toxins, but also their reactions to all kinds of stimuli, such as nutrients or hormones, Dedon says. "We're proposing that any time there's a stimulus, you're going to have a reprogramming [of tRNA] that causes selective translation of proteins you need for the next step in whatever you're going to do," he says.

Lead author of the paper is recent MIT PhD recipient Clement Chan. Other MIT authors are postdocs Yan Ling Joy Pang and Wenjun Deng and research scientist Ramesh Indrakanti. Authors from the University at Albany are Thomas Begley, an associate professor of nanobioscience, and research scientist Madhu Dyavaiah.