INCIDER fluorescent sensors visualize sticky situations

Osaka, Japan – Cells tend to get themselves in and out of “sticky situations” on a regular basis, as they make and break functional connections with each other. Monitoring intercellular interactions is essential for gaining deeper insights into the complex human physiology. Now, researchers from Japan have developed a new way to track some of these adhesive interactions in real time. 

In a recent article published in Communications Biology, researchers led by SANKEN (The Institute of Scientific and Industrial Research) at Osaka University have reported the development of a new fluorescent sensor system for imaging a key protein involved in interactions between cells.

The human body is made up of millions of cells that need to work together to keep everything functioning normally. In order for cells to work well together, they need to stick together, and they do this through the use of adhesion molecules such as neural cadherin (NCad).

“Due to a lack of appropriate detection techniques, it remains unclear when
and where NCad interactions occur,” says lead author of the study Takashi Kanadome. “Conventional sensor molecules have a low resolution and irreversible properties, which makes it challenging to detect dynamic changes in cell–cell interactions.”

To design a better way to visualize NCad-dependent interactions between cells, the researchers started with a set of two sensors that only let off a bright fluorescent signal when they are right next to each other. They inserted each of these sensors into different copies of NCad to generate INCIDERs (fluorescent indicators for the detection of NCad interactions) and then monitored the interactions between cells expressing the new sensor proteins.
“The results were striking,” explains senior author Tomoki Matsuda. “We observed bright fluorescence on the surfaces of interacting cells, indicating that the fluorescent sensors were appropriately activated by cell–cell adhesion.”

Treating the cells with calcium to disrupt the interaction between the paired INCIDER sensor proteins resulted in a decrease in fluorescence, and washing out the calcium increased the fluorescence, showing that this system is reversible and can therefore be used to image dynamic changes in cell interactions. In addition, the fluorescence signal was 70 times stronger than that of the only system that is currently available to detect these kinds of interactions.

“Our study demonstrated that, using the INCIDER system, it is possible to perform high-contrast microscopic imaging of temporal changes in cell–cell N-cadherin interactions,” says Matsuda.

Given that NCad-mediated intercellular adhesion is crucial to a wide range of cells and cellular processes, the INCIDER system is expected to be useful in the fields of developmental biology, neuroscience, and more. In the future, this fundamental technology could be expanded to image interactions between other types of intercellular adhesion proteins.

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The article, “Development of intensiometric indicators for visualizing N-cadherin interaction across cells,” was published in Communications Biology at DOI: 10.1038/s42003-022-04023-2.

About Osaka University

Osaka University was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world, being named Japan's most innovative university in 2015 (Reuters 2015 Top 100) and one of the most innovative institutions in the world in 2017 (Innovative Universities and the Nature Index Innovation 2017). Now, Osaka University is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation. 
Website: https://resou.osaka-u.ac.jp/en