Pusan National University develops novel biosensor to detect DNA damage in real time

Double-strand breaks (DSBs) are a type of DNA damage where both strands of DNA break at the same location. They can  adversely affect cell growth and functioning. Currently, DSBs are detected by immunostaining techniques, which identify markers that accompany DNA damage, such as the protein γH2AX. However, these methods are tedious, and cannot be used to detect DSBs in real time in living specimens.

In a 2023 study, published in Biomaterials Research, researchers describe a fluorescence resonance energy transfer (FRET) biosensor that can detect DSBs in real time, and provide time- and location-based information on yH2AX. "The biosensor we have designed could be useful in areas such as cancer treatment and drug discovery," says Associate Professor Tae-Jin Kim, from Pusan National University, Korea, who led the study.

FRET sensors consist of two fluorescent proteins or dyes—a donor and an acceptor—which investigate interactions between biological molecules. The energy transfer, and consequently, the amount of emitted light (the FRET signal) depends on the distance and orientation between the two dyes.

The researchers attached the fluorescent dyes with proteins that are involved in the cellular response to DNA damage, namely the H2AX substrate and BRCT1 domain. The H2AX substrate is a target for the H2AX protein to bind and become phosphorylated (forming γH2AX). On the other hand, the BRCT1 domain acts as a site for the accumulation of repair proteins, including γH2AX. Thus, when a DSB occurs, γH2AX is attracted to the BRCT1 domain, leading to a conformational change in the fluorescent proteins, thereby causing a change in the FRET signal.

The researchers then confirmed the validity of the sensor by introducing plasmids (DNA that, here, contain instructions to make the FRET sensor inside the cells) encoding the FRET sensor into human embryonic kidney cells (HEK293T) cells. Compared to conventional immunostaining techniques, this biosensor was more sensitive at reacting to the presence of γH2AX, making it more effective at detecting drug- and radiation-induced DSBs.

"Moreover, as changes in the FRET signal give useful indications of the extent of the DNA damage, the sensor can also be used to examine DNA damage and repair mechanisms, optimize cancer treatments, discover and assess DNA repair drugs, and identify DNA damaging factors in the environment," concludes Associate Prof. Kim.

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Reference

DOI: https://doi.org/10.1186/s40824-023-00354-1

Authors: Jung-Soo Suh and Tae-Jin Kim*

Affiliations: Pusan National University, Republic of Korea

About Pusan National University
Pusan National University, located in Busan, South Korea, was founded in 1946, and is now the no. 1 national university of South Korea in research and educational competency. The multi-campus university also has other smaller campuses in Yangsan, Miryang, and Ami. The university prides itself on the principles of truth, freedom, and service, and has approximately 30,000 students, 1200 professors, and 750 faculty members. The university is composed of 14 colleges (schools) and one independent division, with 103 departments in all.    

Website: https://www.pusan.ac.kr/eng/Main.do

About the author
Prof. Tae-Jin Kim is an Associate Professor of Biological Sciences and the Director of the Inter-Biome Optical Imaging Laboratory at Pusan National University (PNU). His group focuses on developing biosensors and advanced imaging techniques to study the mechanisms of cellular processes. The lab's research aims to deepen our understanding of the regulation and communication of signaling pathways within cells, as well as the role of mechanical forces in cellular processes. The lab's research is highly interdisciplinary, drawing from areas such as biochemistry, molecular biology, and biophysics to design new biosensors and imaging technologies. Ultimately, the lab's research seeks to address important biological questions and improve our ability to diagnose and treat diseases, such as cancer. Before coming to PNU, he held the position of PI (senior researcher) at Korea Institute of Science and Technology (KIST). In 2013, Tae-Jin Kim received a PhD in Neuroscience from University of Illinois at Urbana-Champaign.

Lab Website: https://tjkim77.wixsite.com/cmbl  

ORCID id: 0000-0001-7678-0478