Body cells change gears to use less oxygen under stress and crises conditions such as a heart attack or stroke, researchers at Johns Hopkins discovered.
Too little oxygen kills cells by compromising the mitochondria ? the powerhouses that run them. When oxygen is scarce, cells adjust by replacing one protein with an energy-efficient substitute “specialized to keep the motor running smoothly even as it begins to run out of gas,” said Dr. Gregg Semenza, professor of pediatrics and director of the vascular biology program in the Institute for Cell Engineering at Johns Hopkins.
A report on his work is published in today?s issue of the journal Cell.
The cell stretches out its energy supply by swapping a low-speed version of a protein that processes oxygen into water inside the mitochondria, the article states.
“Cells require a constant supply of oxygen,” Semenza said, “so it?s vital for them to quickly react to slight changes in oxygen levels.”
To test the idea, his team compared the growth of human cells in normal oxygen conditions to cells deprived of oxygen. In low oxygen, liver, uterus, lung and colon cells all made the high-efficiency protein. The researchers then exposed mice to hypoxia for a few weeks and found similar changes.
Fine-tuning oxygen use in the mitochondria is essential to keeping down the production of free radicals ? destructive ions of unbound oxygen which can destroy cells. Free radicals have been linked to weakened immune systems and disease, according to the National Institutes of Health.
Cancerous cells are the only tissues that appear to selectively engage the high-efficiency protein, Semenza said, in order to grow faster on limited resources. “We?re trying to understand how the basic metabolism gets altered in cancer cells,” he said.
Similar changes in proteins that process oxygen have been observed in people who have had a stroke as well as one-celled yeasts, he said.
