Synergistic Effects of Chronic Restraint-Induced Stress and Low-Dose 56Fe-particle Irradiation on Induction of Chromosomal Aberrations in Trp53-Heterozygous Mice

Astronauts can develop psychological stress (PS) during space flights due to the enclosed environment, microgravity, altered light-dark cycles, and risks of equipment failure or fatal mishaps. At the same time, they are exposed to cosmic rays including high atomic number and energy (HZE) particles such as iron-56 (Fe) ions. Psychological stress or radiation exposure can cause detrimental effects in humans. An earlier published pioneering study showed that chronic restraint-induced psychological stress (CRIPS) could attenuate Trp53 functions and increase carcinogenesis induced by low-linear energy transfer (LET) γ rays in Trp53-heterozygous (Trp53+/–) mice. To elucidate possible modification effects from CRIPS on high-LET HZE particle-induced health consequences, Trp53+/– mice were received both CRIPS and accelerated Fe ion irradiation. Six-week-old Trp53+/– C57BL/6N male mice were restrained 6 h per day for 28 consecutive days. On day 8, they received total-body Fe-particle irradiation (Fe-TBI, 0.1 or 2 Gy). Metaphase chromosome spreads prepared from splenocytes at the end of the 28-day restraint regimen were painted with the fluorescence in situ hybridization (FISH) probes for chromosomes 1 (green), 2 (red) and 3 (yellow). Induction of psychological stress in our experimental model was confirmed by increase in urinary corticosterone level on day 7 of restraint regimen. Regardless of Fe-TBI, CRIPS reduced splenocyte number per spleen at the end of the 28-day restraint regimen. At 2 Gy, Fe-TBI alone induced many aberrant chromosomes and no modifying effect was detected from CRIPS on induction of aberrant chromosomes. Notably, neither Fe-TBI at 0.1 Gy nor CRIPS alone induced any increase in the frequency of aberrant chromosomes, while simultaneous exposure resulted in a significant increase in the frequency of chromosomal exchanges. These findings clearly showed that CRIPS could enhance the frequency of chromosomal exchanges induced by Fe-TBI at a low dose of 0.1 Gy

Reduced High-Dose Radiation-Induced Residual Genotoxic Damage by Induction of Radioadaptive Response and Prophylactic Mild Dietary Restriction in Mice

Radioadaptive response (RAR) describes a phenomenon in a variety of in vitro and in vivo systems that a low-dose of priming ionizing radiation (IR) reduces detrimental effects of a subsequent challenge IR at higher doses. Among in vivo investigations, studies using the mouse RAR model (Yonezawa Effect) showed that RAR could significantly extenuate high-dose IR-induced detrimental effects such as decrease of hematopoietic stem cells and progenitor cells, acute radiation hematopoietic syndrome, genotoxicity and genomic instability. Meanwhile, it has been demonstrated that diet intervention has a great impact on health, and dietary restriction shows beneficial effects on numerous diseases in animal models. In this work, by using the mouse RAR model and mild dietary restriction (MDR), we confirmed that combination of RAR and MDR could more efficiently reduce radiogenotoxic damage without significant change of the RAR phenotype. These findings suggested that MDR may share some common pathways with RAR to activate mechanisms consequently resulting in suppression of genotoxicity. As MDR could also increase resistance to chemotherapy and radiotherapy in normal cells, we propose that combination of MDR, RAR, and other cancer treatments (i.e., chemotherapy and radiotherapy) represent a potential strategy to increase the treatment efficacy and prevent IR risk in humans

Integrative Annotation of 21,037 Human Genes Validated by Full-Length cDNA Clones

The human genome sequence defines our inherent biological potential; the realization of the biology encoded therein requires knowledge of the function of each gene. Currently, our knowledge in this area is still limited. Several lines of investigation have been used to elucidate the structure and function of the genes in the human genome. Even so, gene prediction remains a difficult task, as the varieties of transcripts of a gene may vary to a great extent. We thus performed an exhaustive integrative characterization of 41,118 full-length cDNAs that capture the gene transcripts as complete functional cassettes, providing an unequivocal report of structural and functional diversity at the gene level. Our international collaboration has validated 21,037 human gene candidates by analysis of high-quality full-length cDNA clones through curation using unified criteria. This led to the identification of 5,155 new gene candidates. It also manifested the most reliable way to control the quality of the cDNA clones. We have developed a human gene database, called the H-Invitational Database (H-InvDB; http://www.h-invitational.jp/). It provides the following: integrative annotation of human genes, description of gene structures, details of novel alternative splicing isoforms, non-protein-coding RNAs, functional domains, subcellular localizations, metabolic pathways, predictions of protein three-dimensional structure, mapping of known single nucleotide polymorphisms (SNPs), identification of polymorphic microsatellite repeats within human genes, and comparative results with mouse full-length cDNAs. The H-InvDB analysis has shown that up to 4% of the human genome sequence (National Center for Biotechnology Information build 34 assembly) may contain misassembled or missing regions. We found that 6.5% of the human gene candidates (1,377 loci) did not have a good protein-coding open reading frame, of which 296 loci are strong candidates for non-protein-coding RNA genes. In addition, among 72,027 uniquely mapped SNPs and insertions/deletions localized within human genes, 13,215 nonsynonymous SNPs, 315 nonsense SNPs, and 452 indels occurred in coding regions. Together with 25 polymorphic microsatellite repeats present in coding regions, they may alter protein structure, causing phenotypic effects or resulting in disease. The H-InvDB platform represents a substantial contribution to resources needed for the exploration of human biology and pathology

Integrative annotation of 21,037 human genes validated by full-length cDNA clones.

publication en ligne. Article dans revue scientifique avec comité de lecture. nationale.National audienceThe human genome sequence defines our inherent biological potential; the realization of the biology encoded therein requires knowledge of the function of each gene. Currently, our knowledge in this area is still limited. Several lines of investigation have been used to elucidate the structure and function of the genes in the human genome. Even so, gene prediction remains a difficult task, as the varieties of transcripts of a gene may vary to a great extent. We thus performed an exhaustive integrative characterization of 41,118 full-length cDNAs that capture the gene transcripts as complete functional cassettes, providing an unequivocal report of structural and functional diversity at the gene level. Our international collaboration has validated 21,037 human gene candidates by analysis of high-quality full-length cDNA clones through curation using unified criteria. This led to the identification of 5,155 new gene candidates. It also manifested the most reliable way to control the quality of the cDNA clones. We have developed a human gene database, called the H-Invitational Database (H-InvDB; http://www.h-invitational.jp/). It provides the following: integrative annotation of human genes, description of gene structures, details of novel alternative splicing isoforms, non-protein-coding RNAs, functional domains, subcellular localizations, metabolic pathways, predictions of protein three-dimensional structure, mapping of known single nucleotide polymorphisms (SNPs), identification of polymorphic microsatellite repeats within human genes, and comparative results with mouse full-length cDNAs. The H-InvDB analysis has shown that up to 4% of the human genome sequence (National Center for Biotechnology Information build 34 assembly) may contain misassembled or missing regions. We found that 6.5% of the human gene candidates (1,377 loci) did not have a good protein-coding open reading frame, of which 296 loci are strong candidates for non-protein-coding RNA genes. In addition, among 72,027 uniquely mapped SNPs and insertions/deletions localized within human genes, 13,215 nonsynonymous SNPs, 315 nonsense SNPs, and 452 indels occurred in coding regions. Together with 25 polymorphic microsatellite repeats present in coding regions, they may alter protein structure, causing phenotypic effects or resulting in disease. The H-InvDB platform represents a substantial contribution to resources needed for the exploration of human biology and pathology

Induction of Genotoxicity by Accelerated Iron Particles in Mouse Hematopoietic System

The genotoxicity induced by Fe particles to that by X-rays was comparatively studied. C57BL/6 female mice (8 weeks old) were exposed to total body irradiation (TBI) from Fe particles (500 MeV/nucleon, 200 keV/μm, 0.1 to 3.0 Gy) or X-rays (200 kVp, 0.1 to 5.0 Gy). The RBE of Fe particles for induction of genotoxicity was determined one and two months after TBI using the frequency of micronuclei in bone marrow erythrocytes. Health condition (body weight and peripheral hemogram) was also investigated. Animals were treated in accordance with the Guidelines for the Care and Use of Laboratory Animals established by NIRS.Reduction in a similar way of the body weight gain was observed in the groups exposed to TBI at high doses from Fe particles or X-rays. X-rays caused more efficiently hematological abnormality. Fe particles and X-rays reduced the ratio of polychromatic erythrocytes (PCEs) to PCEs plus normochromatic erythrocytes (NCEs) in a similar way. Fe particles resulted in more efficiently micronucleated PCEs and NCEs at low doses. The RBE of Fe particles for induction of genotoxicity was higher at a low dose (0.5 Gy) than that at a high dose (3.0 Gy).Work was partially supported by MEXT Grant-in-Aid for Scientific Research on Innovative Areas, Grant Number 15H05935 “Living in Space” and HIMAC Projects 22B258 and 14J286.「日本放射線影響学会第60回大会

Induction of genotoxicity by accelerated heavy iron particles in the hematopoietic system in mice.

Purpose: The genotoxicity induced by high LET iron particles was studied and compared to that by low LET X-rays in the ground-based experiments carried out at NIRS using total body irradiation (TBI) of mice with the Heavy Ion Medical Accelerator in Chiba (HIMAC) and an X-ray generator (Pantak 320S, Shimadzu).Materials and Methods: C57BL/6J Jms strain female mice of 8 weeks old were used. TBI was performed at a dose ranging from 0.1 to 3.0 Gy for iron particles (500 MeV/nucleon, 200 keV/μm), or from 0.1 to 5.0 Gy for X-rays (200 kVp, 0.5 mm Al + 0.5 mm Cu filter). The RBE of iron particles to X-rays for induction of acute genotoxicity and late residual damage in the hematopoietic system was determined respectively at one and two months after TBI using the frequency of micronuclei in bone marrow erythrocytes as the endpoint. The health condition (body weight gain and the hemogram of the peripheral blood) was also investigated. Animals were treated in accordance with the Guidelines for the Care and Use of Laboratory Animals established by NIRS.Results and Conclusions: Reduction of body weight gain after TBI was in a similar way observed in the groups exposed to high doses from iron particles or X-rays. X-rays caused more efficiently hematological abnormality than iron particles. Iron particles and X-rays reduced the ratio of polychromatic erythrocytes (PCEs) to PCEs plus normochromatic erythrocytes (NCEs), an indicator for bone marrow proliferation, in a similar way, while iron particles resulted in more efficiently micronucleated PCEs and NCEs at low doses than X-rays. The relative effectiveness of iron particles to X-rays for induction of genotoxicity in bone marrow erythrocytes was higher at a low dose (0.5 Gy) than that at a high dose (3.0 Gy).Acknowledgments: This work was partially supported by both the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Grant-in-Aid for Scientific Research on Innovative Areas, Grant Number 15H05935 “Living in Space” and three HIMAC Research Project Grants (22B258, 14J286 and 16J295). The expert technical assistance and administrative support of Ms. Hiromi Arai, Mr. Sadao Hirobe, Ms. Mikiko Nakajima, and Ms. Yasuko Morimoto are gratefully acknowledged.COSPAR 2018 （42nd Assembly, 60th Anniversary