Killer waves

Often when a cell dies, its demise comes in a wave, propelled by killer proteins that strike one after the other in something scientists call a trigger wave, new research suggests.

Trigger waves transmit information quickly and continually, and have long been associated with normal tissue development. But until now it wasn’t clear that they’re instrumental in a form of cell death called apoptosis — a natural, and mostly pre-determined, part of healthy cell regulation that also kicks in to kill damaged or diseased cells.

“This work is another example of how nature makes use of these trigger waves — things that most biologists have never heard of — over and over again,” senior author James Ferrell, MD, PhD, professor of chemical and systems biology and of biochemistry, said of the study published Aug. 10 in Science.

He and the lead author, postdoctoral scholar Xianrui Cheng, PhD, used Xenopus frog eggs, which are giant single cells, to observe how death spreads through a cell. In the eggs, cell death occurred with constant and steady progress, indicating that trigger waves propagate the process.

“Sometimes our cells die when we really don’t want them to — say, in neurodegenerative diseases. And sometimes our cells don’t die when we really do want them to — say, in cancer,” Ferrell said. “And if we want to intervene, we need to understand how apoptosis is regulated.”