Research topics

A joint research group involving Dr. Liu Lutan, Associate Professor Shuntaro Takahashi, and Distinguished Professor Naoki Sugimoto from Konan University’s Frontier Institute for Biomolecular Engineering Research (FIBER), along with RIKEN and Kyoto University, has pioneered a method for evaluating DNA quadruplexes formed within cellular mitochondria. The research paper detailing this collaborative achievement has been published in the online edition of Communications Chemistry, a sister journal of the British scientific journal Nature, and was selected as the journal’s Featured Image.

Mitochondria are organelles that synthesize adenosine triphosphate (ATP), the energy source of life. Therefore, mitochondrial activity is critically important for maintaining cellular homeostasis. While cells contain chromosomal DNA within the nucleus, mitochondria also possess their own DNA (mtDNA), which contains genes essential for ATP synthesis. When mtDNA genes mutate for any reason, it can trigger cellular aging or carcinogenesis. One characteristic feature of the cause of these genetic mutations is the formation of quadruplexes on DNA, which is normally double-stranded. Since mtDNA contains many sequences prone to form guanine quadruplexes, developing methods to predict and evaluate the formation of guanine quadruplexes within mitochondria was urgently needed. Therefore, in this study, we examined the formation behavior of DNA quadruplexes using various solutions that mimic the environment inside mitochondria. Furthermore, using a technology developed by Professor Numata and Dr. Yoshinaga at RIKEN and Kyoto University for delivering DNA into mitochondria, we developed an evaluation technique that makes mitochondria fluoresce when guanine quadruplexes form. Results obtained using human cancer cells (HeLa cells) revealed that mitochondria exist in a more molecularly crowded environment than the cell nucleus, making them more conducive to guanine quadruplex formation. We successfully artificially recreated this mitochondrial environment that favorably promotes guanine quadruplex formation. Leveraging these findings, future analysis of how cellular environments influence quadruplexes within mitochondria is expected to contribute to the development of novel biomedical engineering technologies for preventing aging and cancer.

【Communications Chemistry (online edition)】Link to the published page is here.

“Predictability of environment-dependent formation of G-quadruplex DNAs in human mitochondria”

L. Liu, S. Takahashi, S. Ghosh, T. Endoh, N. Yoshinaga, K. Numata, and N. Sugimoto, Communications Chemistry, 8, 135 (2025)