Salk researchers have created a novel imaging method that lets scientists monitor actin. The imaging technique, enables researchers to investigate how actin mediates the cellular "power stations" known as mitochondria divide. Their research is published in the journal, Nature Methods. The novel imaging method will provide important insights on mitochondrial dysfunction, which has been linked to cancer and neurodegenerative diseases.
"Actin is the most abundant protein in the cell, so when you image it, it's all over the cell," says Uri Manor, director of Salk's Biophotonics Core facility. He continues, "Until now, it's been really hard to tell where individual actin molecules of interest are, because it's difficult to separate the relevant signal from all the background."
The new method developed by Manor, and his colleagues, provide a new way to image actin. Instead of tagging all the actin in the cell with fluorescence, they developed an actin probe targeted to the outer membrane of mitochondria. The actin needs to be within 10 nanometers of the mitochondria in order to attach to the sensor, causing the fluorescence signal to increase.
Manor's team observed hotspots of actin were located at the same locations where the endoplasmic reticulum crosses the mitochondria. Researchers discovered that 97 percent of mitochondrial fission sites had actin fluorescing around them.
"This is the clearest evidence I've ever seen that actin is accumulating at fission sites," says Cara Schiavon, co-first author of the paper. "It's much easier to see than when you use any other actin marker."
In the future, the Manor’s team will look at how genetic mutations might affect actin's interactions with the mitochondria. They also plan to adapt the actin probes to visualize actin that's close to other cellular membranes.