细胞的应急自救系统

Toxic¹ chemicals wreak² havoc³ on cells, damaging DNA⁴ and other critical molecules⁵. A new study from researchers at MIT and the University at Albany reveals how a molecular⁶ emergency-response system shifts the cell into damage-control mode and helps it survive such attacks by rapidly producing proteins that counteract⁷（抵消） the harm. Peter Dedon, a professor of biological engineering at MIT, and colleagues had previously⁸ shown that cells treated with poisons such as arsenic⁹（砒霜） alter their chemical modification¹⁰ 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 delved¹¹ into how these modifications¹² 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 machinery¹³ away from its routine activities to emergency action. "In the end, a stepwise mechanism¹⁴ 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 toxins¹⁵, but also their reactions to all kinds of stimuli¹⁶, such as nutrients¹⁷ or hormones¹⁸, Dedon says. "We're proposing that any time there's a stimulus¹⁹, 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.

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Lead author of the paper is recent MIT PhD recipient²⁰ Clement²¹ Chan. Other MIT authors are postdocs Yan Ling Joy Pang²² 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. #