In June 2026, a joint team from the University of Tokyo, Meisei University, and RIKEN in Japan announced an important research breakthrough: the team resolved, for the first time, the complex structure formed by the key DNA repair proteins Rad26/CSB and the nucleosome, revealing how gene transcription and DNA repair are seamlessly coordinated along the chromosome. This discovery advances basic life sciences research and also provides an important foundation for future treatment strategies for DNA repair-related diseases, such as Cockayne syndrome.
Research Highlights
First-ever resolution of the Rad26/CSB–nucleosome complex structure: using cryo-electron microscopy (Cryo-EM), the research team obtained the three-dimensional structure of Rad26/CSB bound to the nucleosome, providing critical visual evidence for understanding the DNA repair mechanism.
Discovery of a unique binding mode: Rad26/CSB binds nucleosomal DNA in a way that differs from conventional chromatin remodeling factors, producing a distinctive structural bend particularly at the DNA's "entry-exit region," making it easier for repair factors to reach the site of damage.
Revealing a self-inhibition release mechanism: the study found that Rad26/CSB has a built-in self-inhibition system; once it transfers from a stalled RNA polymerase II onto the nucleosome, this inhibition is released, activating its chromatin remodeling function and making it the central bridge linking "gene transcription" and "DNA repair."
Why This Research Matters for Medicine
DNA in human cells is constantly being damaged by factors such as UV light, chemical exposure, and reactive oxygen species. When damage occurs while a gene is actively being read, RNA polymerase II can stall, gene expression can be interrupted, and repair factors may struggle to access the damaged region — which is why cells rely on a mechanism called transcription-coupled repair (TC-NER) to quickly fix this type of damage. The Rad26/CSB mechanism revealed in this study is a core part of that repair process, and its structure and regulatory mechanism could become a foundation for future treatment strategies, with relevant implications for Cockayne syndrome, certain inherited neurological conditions, and diseases related to genomic instability.
What This Means for Patients Seeking Treatment in Japan
Research findings from the University of Tokyo and RIKEN are often translated relatively quickly into new directions for rare disease treatment strategies. For patients and families affected by DNA repair-related conditions such as Cockayne syndrome or certain neurodegenerative diseases, progress in this kind of foundational research carries long-term significance, and reflects Japan's broader strength across basic and translational medicine. MIZUHO PHARMA will continue to track the clinical translation of related research.