Our cells contain two different genomes: one in the cell nucleus and another in the mitochondria. Each has its own distinct machinery and evolutionary origin.
Both genomes contribute proteins to build the power plants that fuel our cells. For years, researchers have wondered: Do the nucleus and mitochondria talk to each other to coordinate energy production? If so, how?
To find out, members of the lab of Stirling Churchman, assistant professor of genetics at Harvard Medical School, are eavesdropping on the conversation.
They report in Nature on May 11 that in Saccharomyces cerevisiae, or baker’s yeast, the nucleus and mitochondria do work together. They discovered that the coordinated effort is directed by the nucleus and occurs at a later stage than anticipated, not when genes are read but instead when proteins are made.
“A lot of attention has gone to studying gene expression and translation in the cell nucleus and cytosol”—the fluid in which cell organelles float—“but we didn’t know much about them in the mitochondria,” said Mary Couvillion, a postdoctoral researcher in the Churchman lab and first author of the paper.
The team was able to discover “this really elegant synchronization,” Couvillion said, by taking RNA sequencing methods and translation protocols designed to study the nuclear genome and modifying them to study the mitochondrial genome.
The researchers are making these tools available so others can use them to further investigate questions such as how mitochondrial genes respond to shifting energy demands that occur during physical activity, eating, embryonic development and aging.
Although the findings still need to be confirmed in human cells, the results of this study could also help researchers better understand mitochondrial disorders as well as diseases and conditions that have been linked to mitochondrial dysfunction, such as cancer, neurodegeneration, obesity and aging.