Implication of E3 ligase RAD18 in UV-induced mutagenesis in human induced pluripotent stem cells and neuronal progenitor cells

Shimada, Mikio*; Tokumiya, Takumi*; Miyake, Tomoko*; Tsukada, Kaima*; Kanzaki, Norie; Yanagihara, Hiromi*; Kobayashi, Junya*; Matsumoto, Yoshihisa*

Journal of Radiation Research (Internet), 64(2), p.345 - 351, 2023/03

https://doi.org/10.1093/jrr/rrac099

Yields of strand breaks and base lesions induced by soft X-rays in plasmid DNA

Yokoya, Akinari; Fujii, Kentaro; Ushigome, Takeshi; Shikazono, Naoya; Urushibara, Ayumi; Watanabe, Ritsuko

Radiation Protection Dosimetry, 122(1-4), p.86 - 88, 2006/12

https://doi.org/10.1093/rpd/ncl408

We have studied yields of DNA damages induced by soft X-rays obtained from a conventional soft X-ray machine in a LET region between -rays and ultrasoft X-rays. Practically soft X-rays with a broad energy spectrum emitted from a target of heavy metal, such as tungsten, have been widely used not only for radiobiological experiments but also for medical application such as mammography. Radiation weighting factors for these soft X-rays have been assigned to be 1 by ICRP. However, the fraction of a large number of low energy photons in the spectrum (below several tens keV) provided by bremsstrahlung is expected to be more effective for DNA damage induction than -rays since low energy photo- and Auger electrons predominantly ejected in consequence of a photoelectric effect can produce dense clusters of ionization/excitation on DNA molecules. We have examined the yield of DNA strand breaks induced by white soft X-rays (150 kVp, tungsten target). Yields of base lesions revealed by base excision repair enzymes will be also presented.

Clustered DNA damage induced by ionizing radiaton

Yokoya, Akinari; Shikazono, Naoya; Urushibara, Ayumi; Fujii, Kentaro; Akamatsu, Ken; Watanabe, Ritsuko

Hoshasen Seibutsu Kenkyu, 40(2), p.168 - 184, 2005/06

http://ci.nii.ac.jp/naid/40006828265

Ionizing radiation causes modifications in a DNA molecule depending on the characteristic tack-structure in which two or more isolated lesions arise in a few nm scale (1 or 2 helical turn of DNA), known as "clustered DNA damage". These clustered DNA damages could be distinct from those by reactive oxygen species (ROS) endogenously induced on their severity of induction of biological effects such as mutation. However, the studies on the nature and repair mechanism of clustered DNA damage have still been behind because of the technical difficulties on determination of the chemical structure and yield. This article reviews some experimental evidences of the clustered DNA damages in this research field, as well as our recent progress on the studies on the clustered DNA damages using both molecular biological techniques and synchrotron spectroscopic method.

Molecular dynamics of 8-oxoguanine lesioned B-DNA molecule; Structure and energy analysis

Pinak, M.; O'Neill, P.*; Fujimoto, Hirofumi; Nemoto, Toshiyuki*

AIP Conference Proceedings 708, p.310 - 313, 2004/05

https://doi.org/10.1063/1.1764151

The multiple nanosecond molecular dynamics simulations of DNA mutagenic oxidative lesion - 7,8-dihydro-8-oxoguanine (8-oxoG), complexed with the repair enzyme - human oxoguanine glycosylase 1 (hOGG1) in a physiological aqueous environment, were performed in order to describe the structural and energy changes in DNA and the dynamical process of DNA-enzyme complex formation. In complex the N-terminus of arginine 324 was found located close to the phosphodiester bond of the nucleotide with 8-oxoG enabling chemical reaction(s) between the amino acid and the lesion. The recognition of lesion on DNA, its recognition by repair enzyme and the formation of stable DNA-enzyme complex are necessary conditions for the onset of the successful enzymatic repair process.

Selected materials of the international workshop on radiation risk and its origin at molecular and cellular level; February 6-7, 2003

Pinak, M.

JAERI-Conf 2003-011, 113 Pages, 2003/09

JAERI-Conf-2003-011.pdf:10.08MB

The workshop "International Workshop on Radiation Risk and its Origin at Molecular and Cellular Level" was held at The Tokai Research Establishment, Japan Atomic Energy Research Institute, on the 6th and 7th of February 2003. The Laboratory of Radiation Risk Analysis of JAERI organized it. This international workshop attracted scientists from several different scientific areas, including radiation physics, radiation biology, molecular biology, crystallography of biomolecules, modeling and bio-informatics. Several foreign and domestic keynote speakers addresses the very fundamental areas of radiation risk and tried to establish a link between the fundamental studies at the molecular and cellular level and radiation damages at the organism. The symposium consisted of 13 oral lectures, 10 poster presentations and panel discussion. The 108 participants attended the workshop. This publication comprises of proceedings of oral and poster presentations where available. For the rest of contributions the abstracts or/and selections of presentation materials are shown instead.

Effects of hydration on the induction of strand breaks, base lesions, and clustered damage in DNA films by -radiation

Yokoya, Akinari; Cunniffe, S. M. T.*; Stevens, D. L.*; O'Neill, P.*

Journal of Physical Chemistry B, 107(3), p.832 - 837, 2003/01

https://doi.org/10.1021/jp0270708

no abstracts in English

Characterization of RecA424 and RecA670 proteins from

Sato, Katsuya; Narumi, Issei; Kikuchi, Masahiro; Kitayama, Shigeru; Yanagisawa, Tadashi*; Yamamoto, Kazuo; Watanabe, Hiroshi

Journal of Biochemistry, 131(1), p.121 - 129, 2002/01

https://doi.org/10.1093/oxfordjournals.jbchem.a003066

RecA protein is considered to be the most important participant in the radiation resistance of . We identified a new mutation () in the DNA-repair deficient mutant strain KI696, the phenotype of which is remarkably different from mutant strain rec30 carrying . In vitro, neither RecA424 nor RecA670 could promote DNA strand exchange, indicating that both RecA424 and Rec670 are defective in recombination activity. RecA424 promoted the autocleavage reaction of LexA in vitro, whereas RecA670 did not. The LexA level in KI696 was decreased following -irradiation. However, the LexA level in strain rec30 was constant irrespective of irradiation. These results indicate that RecA424 retains co-protease activity, whereas RecA670 does not. While strain rec30 is extremely radiation sensitive, strain KI696 is only slightly sensitive. Together, these observations suggest that the co-protease activity rather than the recombination activity of RecA contributes to the radiation resistance in .