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Published on: August 2, 2024
Cloning of canine Ku80 and its localization and accumulation at DNA damage sites
Manabu Koike1, Yasutomo Yutoku1, Aki Koike1
1National Institute of Radiological Sciences National Institutes for Quantum and Radiological Science and Technology Chiba Japan.
Abstract:
Molecularly targeted therapies have high specificity and significant cancer-killing effect. However, their antitumor effect might be greatly diminished by variation in even a single amino acid in the target site, as it occurs, for example, as a consequence of SNPs. Increasing evidence suggests that the DNA repair protein Ku80 is an attractive target molecule for the development of next-generation radiosensitizers for human cancers. However, the localization, post-translational modifications (PTMs), and complex formation of Ku80 have not been elucidated in canines. In this study, for the first time, we cloned, sequenced, and characterized canine Ku80 cDNA. Our data show that canine Ku80 localizes in the nuclei of interphase cells and is quickly recruited at laser-induced double-strand break sites. Comparative analysis shows that canine Ku80 had only 82.3% amino acid identity with the homologous human protein, while the nuclear localization signal (NLS) in human and canine Ku80 is evolutionarily conserved. Notably, some predicted PTM sites, including one acetylation site and one sumoylation site within the NLS, are conserved in the two species. These findings suggest that the spatial and temporal regulation of Ku80 might be conserved in humans and canines. However, our data indicate that the expression of Ku80 is considerably lower in the canine cell lines examined than in human cell lines. These important findings might be useful to better understand the mechanism of the Ku80-dependent DNA repair and for the development of potential next-generation radiosensitizers targeting common targets in human and canine cancers.
Insights
Researchers characterized canine Ku80, a DNA repair protein. Canine Ku80 shares conserved features with human Ku80, suggesting potential for developing radiosensitizers targeting both human and canine cancers.
Area of Science:
- Molecular Biology
- Cancer Research
- Genetics
Background:
- Molecularly targeted therapies offer specificity but can be limited by target site variations like single nucleotide polymorphisms (SNPs).
- The DNA repair protein Ku80 is a promising target for next-generation radiosensitizers in human cancers.
- Key aspects of canine Ku80, including its localization, post-translational modifications (PTMs), and complex formation, remain largely uncharacterized.
Purpose of the Study:
- To clone, sequence, and characterize canine Ku80 cDNA.
- To investigate the localization and functional conservation of canine Ku80 compared to its human counterpart.
- To explore the potential of canine Ku80 as a target for radiosensitizer development in both human and canine cancers.
Main Methods:
- Cloning and sequencing of canine Ku80 cDNA.
- Cellular localization studies using microscopy to observe Ku80 in interphase nuclei and at DNA double-strand break sites.
- Comparative sequence analysis between canine and human Ku80, including identification of conserved regions and predicted post-translational modification sites.
- Quantitative analysis of Ku80 expression levels in canine and human cell lines.
Main Results:
- Canine Ku80 cDNA was successfully cloned and sequenced.
- Canine Ku80 localizes to the nucleus and is rapidly recruited to sites of DNA double-strand breaks.
- Comparative analysis revealed 82.3% amino acid identity between canine and human Ku80, with conserved nuclear localization signals (NLS) and key predicted PTM sites (acetylation, sumoylation).
- Ku80 expression was significantly lower in examined canine cell lines compared to human cell lines.
Conclusions:
- Canine Ku80 shares significant structural and functional similarities with human Ku80, including conserved NLS and PTM sites, suggesting conserved spatial and temporal regulation.
- The lower expression of Ku80 in canine cells compared to human cells warrants further investigation.
- These findings provide a foundation for understanding Ku80-dependent DNA repair mechanisms and developing novel radiosensitizers targeting conserved Ku80 functions in both human and canine cancers.
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