Prior to the advent of the tools and technologies for live-cell imaging, biologists relied on single snapshots of cellular events to understand how cells function.
Yet without the ability to observe dynamic cellular processes in real-time, it was difficult, if not impossible, to understand what was going on at the molecular level.
“The difference between taking snapshots of the process and watching a movie is just night and day,” says David Drubin, Ph.D., professor of cell and developmental biology at the University of California, Berkeley, whose lab uses fluorescence to understand the intricate details underlying clathrin-mediated endocytosis.
Over the past few decades, developments in two major research areas have made it possible for researchers to unveil more and more about how everyday cellular processes occur. Scientists have developed genetically encoded biosensors that allow cells to express fluorescent protein fusions that light up under a fluorescence microscope. On the imaging side, researchers have developed technologies that allow real-time visualization of the spatial arrangement of fluorescently labeled proteins inside live cells.
These two research fronts converge into a field known as live-cell imaging. Despite the major strides made in the field in recent years, there is still much room for growth, and continual advancements will enable researchers to address fundamental biological questions about how cells function.
Once we understand the molecular basis of normal cellular processes, we can begin to understand how alterations to these functions lead to disease, says Mark Rizzo, Ph.D., assistant professor of physiology at the University of Maryland. Dr. Rizzo uses live-cell imaging techniques to understand the molecular and cellular details underlying the progression of diabetes.
Dr. Rizzo’s lab studies mouse pancreatic β cells, which are responsible for secreting insulin in response to a rise in glucose levels. The process of insulin secretion is tightly regulated by glucokinase and several cellular enzymes. Glucokinase is known to play a key role in regulating blood sugar levels, but what remains unclear is whether the mechanism of glucokinase regulation breaks down during the progression of type 2 diabetes, Dr. Rizzo says. If so, does it promote disease progression, or is it simply correlated?
In the field of diabetes research, these and many other questions remain, but Dr. Rizzo says one thing is clear: “There’s a lot of research out there now that says that early intervention of diabetes produces the best prognosis.” With a better understanding of how the disease develops, researchers will be better positioned to develop therapeutic interventions.
Live-cell imaging is essential to this work, Dr. Rizzo says, because it allows his research team to observe what is happening on the time scale on which glucokinase is regulated. Researchers in his lab have developed a cyan fluorescent protein (CFP)-glucokinase fusion protein that can be expressed in pancreatic β cells isolated from normal mice. Using live-cell imaging, they have demonstrated for the first time that glucokinase is activated on the surface of insulin secretory granules.
Dr. Rizzo is currently working on developing better and brighter reagents that will enable faster data acquisition and will require less reagent, and plans to continue fundamental research on diabetes as well.