Tissues and organs form and grow through a highly regulated process of cell division known as mitosis. Normally, cells stop dividing once they start performing specialized functions. If the process is incorrectly regulated, however, cells divide too fast or too slowly. Accelerated cell division can result in cancers that proliferate rapidly unless anti-cancer agents intervene.
To measure cell division timing, the researchers incorporated fluorescent proteins, called biosensors, into the cell nuclei. When used with a specialized microscopy technique called total internal reflection fluorescence, the biosensor glows when the nuclear membrane breaks down, passes through the surrounding cellular material and is released into the cell membrane. When genetic material is re-enclosed in the nuclear envelope of newly formed cells, the biosensor moves back into the reformed nucleus and there is no fluorescence. The effect is like a light switch being turned on and off, signaling the start and end of the cell division process, respectively.
The biosensor is a first example of new types of probes designed to observe and measure cellular processes in real time rather than just looking at before-and-after static snapshots, said Tobias Meyer, PhD, associate professor of molecular pharmacology, who led the research team. "The biosensor will be useful for discovering genes involved in cell proliferation and cancer," he said.