Researchers at the University of North Carolina Lineberger Comprehensive Cancer Center can illuminate cells from within using an embedded “biological flashlight,” and then use the light to control the cell’s function.

In a proof-of-concept study published in the journal ACS Synthetic Biology, researchers describe an advance in “optogenetics,” a field in which scientists use light to control cells with light-sensitive proteins.

 

“Our technology revolves around the light itself – it’s no longer external; instead, it’s now generated within any cell wherever we put it,” said UNC Lineberger’s Antonio Amelio, PhD, assistant professor in the UNC Adams School of Dentistry. “We then used the technology to control existing optogenetic tools.”

UNC Lineberger's Antonio Amelio, PhD.
UNC Lineberger’s Antonio Amelio, PhD.

More than 15 years ago, scientists discovered laboratory techniques that allowed them to use light to control functions in individual cells, and used them to study neurons brain circuitry. This technology works by using light to trigger proteins that are activated by light at certain wavelengths. Since then, Amelio said researchers have developed different tools to control living cells in the laboratory, and this has led to discoveries important to neurobiology, cancer biology, molecular biology and other fields.

A problem for this field, however, is the exterior light source used to control cells can damage living cells, the researchers said.

Kshitij Parag-Sharma
Kshitij Parag-Sharma is a graduate student in the UNC School of Medicine Department of Cell Biology and Physiology.

“The optogenetic systems are already used in dozens of different fields from neurobiology to molecular and synthetic biology,” said Kshitij Parag-Sharma, the study’s first author and a graduate student in the UNC School of Medicine Department of Cell Biology and Physiology. “The problem, for the most part, has been that when you bring cells into play, and you’re using really bright light from sources like lasers, then they can cause light-induced damage and kill cells over time. However, if your cells can self-illuminate, then there is minimal damage or phototoxicity, as we demonstrated in our study.”

Building upon previous work

The latest study builds off of previous work by Amelio’s lab in which they developed a self-illuminating protein complex called the LumiFluor by fusing a naturally-occurring bioluminescent enzyme found in shrimp with another fluorescent protein from jellyfish.

In their recent study, they described how they adapted the LumiFluor so that it could be switched on and off from within the cell. Then they used it to remotely control light-sensitive proteins, which were genetically engineered into the cell. Together, they called the combination of the adapted LumiFluor with the light-sensitive proteins “BEACON,” or BRET-Activated Optogenetics.

They showed they could turn “on” the biologic light using a certain drug to generate light from within the cell. Further, they demonstrated they could engineer BEACON to shine only in certain regions of the cell, giving the researchers unprecedented control over sub-cellular processes.

Amelio said their study proved they could control the duration and strength of the light.

Benefits to using the “biological flashlight”

“Not only have we shown we can engineer biologic light of different colors and intensities inside a cell, but we can also control its location within the cell,” Amelio said. “You don’t have to use an external light source – like a laser or an LED. You can generate the light where you want it and when you need it within the cell to control a specific biological function or process.”

There are benefits to using their embedded light over an external light source, Amelio said, including it does not create as much heat.

“The intensities are lower, and they’re at the location where you want them in the cell, so you don’t need very much direct light,” he said.

They plan to use their tool to visualize and better understand signaling pathways that control cancer cell behavior, and to potentially investigate using it to study regulation of light-activated drugs. Amelio said they envision studying this tool to turn on drugs when and where they want the drug released.

“This is a really exciting finding that will have diverse applications for cell, molecular and cancer biology research,” Parag-Sharma said. “We can combine our BEACON approach with other systems to engineer synthetic circuits that allow us to study complex signaling paradigms involved in health and disease.”

Authors and Disclosures

In addition to Amelio and Parag-Sharma, other authors include Colin P. O’Banion, Erin C. Henry, Adele M. Musicant, John L. Cleveland and David S. Lawrence.

The study was supported by the National Cancer Institute, a National Institutes of Health/National Institute of General Medical Sciences training grant, National Institute of Neurological Disorders and Stroke and National Cancer Institute grant, the University Cancer Research Fund, UNC Lineberger Tier 3 Developmental Award, the Corter-Couch Endowed Chair for Cancer Research, and an NCI Howard Temin Pathway to Independence Award in Cancer Research.