DNA is the hereditary material in humans and almost all other organisms. It is essential for maintaining accurate transmission of genetic information. In the life cycle, DNA replication, cell division, or genome damag...DNA is the hereditary material in humans and almost all other organisms. It is essential for maintaining accurate transmission of genetic information. In the life cycle, DNA replication, cell division, or genome damage, including that caused by endogenous and exogenous agents, may cause DNA aberrations. Of all forms of DNA damage, DNA double-strand breaks(DSBs) are the most serious. If the repair function is defective, DNA damage may cause gene mutation, genome instability, and cell chromosome loss, which in turn can even lead to tumorigenesis. DNA damage can be repaired through multiple mechanisms. Homologous recombination(HR) and non-homologous end joining(NHEJ) are the two main repair mechanisms for DNA DSBs. Increasing amounts of evidence reveal that protein modifications play an essential role in DNA damage repair.Protein deubiquitination is a vital post-translational modification which removes ubiquitin molecules or polyubiquitinated chains from substrates in order to reverse the ubiquitination reaction. This review discusses the role of deubiquitinating enzymes(DUBs) in repairing DNA DSBs. Exploring the molecular mechanisms of DUB regulation in DSB repair will provide new insights to combat human diseases and develop novel therapeutic approaches.展开更多
Objective To explore if strand breaks of DNA in human early chorionic villus cells in uterus were induced by diagnostic ultrasound and to evaluate the method used for detection of single-stranded breaks and double-str...Objective To explore if strand breaks of DNA in human early chorionic villus cells in uterus were induced by diagnostic ultrasound and to evaluate the method used for detection of single-stranded breaks and double-stranded breaks in human DNA. Methods 60 normal pregnant women aged 20-30, who underwent artificial abortion during 6-8 weeks of gestation, were randomly divided into 2 experimental groups: All 30 cases were exposed to diagnostic ultrasound in uterus for 10 minutes, and 24 hours later chorionic villi were extracted; the other 30 cases were taken as the control group. Single-stranded DNA and double-stranded DNA in villus cells in all cases were isolated by the alkaline unwinding combined with hydroxylapatite chromatography, and were quantitatively detected using 32 P-labeled Alu probe for dot-blotting hybridization. Results There was no significant difference in quantity and percentage in single-stranded DNA and double-stranded DNA between 2 groups (P>0.05). 32 P-Alu probe could only hybridize with human DNA, and could detect DNA isolated from as few as 2.5×10 3 chorionic villus cells and 0.45ng DNA in human leukocytes. Conclusion The results suggested that there were no DNA strand damages in human chorionic villus cells when the uterus was exposed to diagnostic ultrasound for 10 minutes. The method,^(32)P-Alu probe for dot-blotting hybridization, was even more specific, sensitive and accurate than conventional approaches.展开更多
DNA damage is one of the most common threats to meiotic cells.It has the potential to induce infertility and genetic abnormalities that may be passed to the embryo.Here,we reviewed exogenous factors which could induce...DNA damage is one of the most common threats to meiotic cells.It has the potential to induce infertility and genetic abnormalities that may be passed to the embryo.Here,we reviewed exogenous factors which could induce DNA damage.Specially,we addressed the different effects of DNA damage on mouse oocytes and embryonic development.Complex DNA damage,doublestrand breaks,represents a more difficult repair process and involves various repair pathways.Understanding the mechanisms involved in DNA damage responses may improve therapeutic strategies for ovarian cancer and fertility preservation.展开更多
Double-strand breaks(DSBs),one class of the most harmful DNA damage forms that bring elevated health risks,need to be repaired timely and effectively.However,an increasing number of environmental pollutants have been ...Double-strand breaks(DSBs),one class of the most harmful DNA damage forms that bring elevated health risks,need to be repaired timely and effectively.However,an increasing number of environmental pollutants have been identified to impair DSB repair from various mechanisms.Our previous work indicated that the formation of unsaturated Rec A nucleofilaments plays an essential role in homology recombination(HR) pathway which can accurately repair DSBs.In this study,by developing a benzonase cutting protection assay and combining it with traditional electrophoretic mobility shift assay(EMSA) analysis,we further investigated the assembly patterns of four Rec A mutants that display differential DSB repair ability and ATPase activity.We observed that the mutants(G204S and S69G) possessing both ATP hydrolysis and DSB repair activities form unsaturated nucleofilaments similar to that formed by the wild type Rec A,whereas the other two ATP hydrolysis-deficient mutants(K72R and E96D) that fail to mediate HR form more compacted nucleofilaments in the presence of ATP.These results establish a coupling of ATPase activity and effective DSB repair ability via the assembly status of Rec A nucleofilaments.This linkage provides a potential target for environmental factors to disturb the essential HR pathway for DSB repair by suppressing the ATPase activity and altering the assembly pattern of nucleofilaments.展开更多
The purpose of the study was to investigate if the high gradient strength and slew rate used for long MRI-thermometry monitoring could cause DNA double-stranded breaks (DSBs). To this end, an enzyme-linked immunosorbe...The purpose of the study was to investigate if the high gradient strength and slew rate used for long MRI-thermometry monitoring could cause DNA double-stranded breaks (DSBs). To this end, an enzyme-linked immunosorbent assay (ELISA) was used to quantify γH2AX, a molecular marker for DSBs, in the blood of mice after a 6-hour exposure to magnetic resonance imaging (MRI). Fourteen CF-1 female mice were separated into 4 experimental groups: Untreated negative control, MRI-treated, MRI-Control, and exposed to ionizing radiation positive control. Untreated negative control was used as a baseline for ELISA to quantify γH2AX. MRI-treated consisted of a 6-hour continuous magnetic resonance imaging (MRI) echo planar imaging (EPI) sequence with a slew rate of 192 mT/m/s constituting a significantly longer imaging time than routine clinical imaging. MRI-control mice were maintained under the same conditions outside the MRI scanner for 6-hours. Mice in the irradiation group served as a positive control of DSBs and were exposed to either 2 Gy, 5 Gy or 10 Gy of ionizing radiation. DSBs in the blood lymphocytes from the treatment groups were analyzed using the γH2AX ELISA and compared. Total protein concentration in lysates was determined for each blood sample and averaged 1 ± 0.35 mg/mL. Irradiated positive controls were used to test radiation dose-dependency of the γH2AX ELISA assay where a linear dependency on radiation exposure was observed (r<sup>2</sup> = 0.93) between untreated and irradiated samples. Mean and standard error mean of γH2AX formation were calculated and compared between each treatment group. Repeated measures 1-way ANOVA showed statistically significant differences between the means of irradiated controls and both the MRI-control and MRI-treated groups. There was no statistically significant difference between the MRI-treated samples and the MRI-control groups. Our results show that long MRI exposure at a high slew rate did not cause increased levels of γH2AX when compa展开更多
DNA双链断裂(double-strand breaks,DSBs)修复对于保证基因组完整性以及维持细胞的平衡稳定性起着关键作用。p53结合蛋白1(p53-binding protein 1,53BP1)是针对产生的双链断裂损伤做出反应的重要调控因子。目前,研究人员对于53BP1被招...DNA双链断裂(double-strand breaks,DSBs)修复对于保证基因组完整性以及维持细胞的平衡稳定性起着关键作用。p53结合蛋白1(p53-binding protein 1,53BP1)是针对产生的双链断裂损伤做出反应的重要调控因子。目前,研究人员对于53BP1被招募到受损的染色质上的过程,以及53BP1在DSBs修复过程中阻止同源重组(homologous recombination,HR)的同时推动非同源末端连接(non-homologous end-joining,NHEJ)的过程,已经有了新的认识。并且,近期的研究结果启发科学家们提出了一种新的模型,即53BP1的招募需要直接识别DSBs特异性的组蛋白密码,而53BP1发挥作用时的通路选择则与BRCA1蛋白的拮抗作用有关。结合近年来有关53BP1的研究进展,主要综述了53BP1的结构与功能特点,其作为调控因子在DSBs修复过程中发挥的作用,以及53BP1达到有效聚集的方式。展开更多
基金supported by the National Natural Science Foundation of China (Nos. 91749115 and 81872298)the Natural Science Foundation of Jiangxi Province (No. 20181BAB205044), China。
文摘DNA is the hereditary material in humans and almost all other organisms. It is essential for maintaining accurate transmission of genetic information. In the life cycle, DNA replication, cell division, or genome damage, including that caused by endogenous and exogenous agents, may cause DNA aberrations. Of all forms of DNA damage, DNA double-strand breaks(DSBs) are the most serious. If the repair function is defective, DNA damage may cause gene mutation, genome instability, and cell chromosome loss, which in turn can even lead to tumorigenesis. DNA damage can be repaired through multiple mechanisms. Homologous recombination(HR) and non-homologous end joining(NHEJ) are the two main repair mechanisms for DNA DSBs. Increasing amounts of evidence reveal that protein modifications play an essential role in DNA damage repair.Protein deubiquitination is a vital post-translational modification which removes ubiquitin molecules or polyubiquitinated chains from substrates in order to reverse the ubiquitination reaction. This review discusses the role of deubiquitinating enzymes(DUBs) in repairing DNA DSBs. Exploring the molecular mechanisms of DUB regulation in DSB repair will provide new insights to combat human diseases and develop novel therapeutic approaches.
文摘Objective To explore if strand breaks of DNA in human early chorionic villus cells in uterus were induced by diagnostic ultrasound and to evaluate the method used for detection of single-stranded breaks and double-stranded breaks in human DNA. Methods 60 normal pregnant women aged 20-30, who underwent artificial abortion during 6-8 weeks of gestation, were randomly divided into 2 experimental groups: All 30 cases were exposed to diagnostic ultrasound in uterus for 10 minutes, and 24 hours later chorionic villi were extracted; the other 30 cases were taken as the control group. Single-stranded DNA and double-stranded DNA in villus cells in all cases were isolated by the alkaline unwinding combined with hydroxylapatite chromatography, and were quantitatively detected using 32 P-labeled Alu probe for dot-blotting hybridization. Results There was no significant difference in quantity and percentage in single-stranded DNA and double-stranded DNA between 2 groups (P>0.05). 32 P-Alu probe could only hybridize with human DNA, and could detect DNA isolated from as few as 2.5×10 3 chorionic villus cells and 0.45ng DNA in human leukocytes. Conclusion The results suggested that there were no DNA strand damages in human chorionic villus cells when the uterus was exposed to diagnostic ultrasound for 10 minutes. The method,^(32)P-Alu probe for dot-blotting hybridization, was even more specific, sensitive and accurate than conventional approaches.
基金This study was supported by the National Natural Science Foundation of China(31171376 and 31401276)National Basic Research Program of China(2012CB944401).
文摘DNA damage is one of the most common threats to meiotic cells.It has the potential to induce infertility and genetic abnormalities that may be passed to the embryo.Here,we reviewed exogenous factors which could induce DNA damage.Specially,we addressed the different effects of DNA damage on mouse oocytes and embryonic development.Complex DNA damage,doublestrand breaks,represents a more difficult repair process and involves various repair pathways.Understanding the mechanisms involved in DNA damage responses may improve therapeutic strategies for ovarian cancer and fertility preservation.
基金supported by the National Natural Science Foundation of China (Nos.21927807 and 91743201)the Ministry of Science and Technology of China (Nos.2018YFC1005003 and Y9L10301)。
文摘Double-strand breaks(DSBs),one class of the most harmful DNA damage forms that bring elevated health risks,need to be repaired timely and effectively.However,an increasing number of environmental pollutants have been identified to impair DSB repair from various mechanisms.Our previous work indicated that the formation of unsaturated Rec A nucleofilaments plays an essential role in homology recombination(HR) pathway which can accurately repair DSBs.In this study,by developing a benzonase cutting protection assay and combining it with traditional electrophoretic mobility shift assay(EMSA) analysis,we further investigated the assembly patterns of four Rec A mutants that display differential DSB repair ability and ATPase activity.We observed that the mutants(G204S and S69G) possessing both ATP hydrolysis and DSB repair activities form unsaturated nucleofilaments similar to that formed by the wild type Rec A,whereas the other two ATP hydrolysis-deficient mutants(K72R and E96D) that fail to mediate HR form more compacted nucleofilaments in the presence of ATP.These results establish a coupling of ATPase activity and effective DSB repair ability via the assembly status of Rec A nucleofilaments.This linkage provides a potential target for environmental factors to disturb the essential HR pathway for DSB repair by suppressing the ATPase activity and altering the assembly pattern of nucleofilaments.
文摘The purpose of the study was to investigate if the high gradient strength and slew rate used for long MRI-thermometry monitoring could cause DNA double-stranded breaks (DSBs). To this end, an enzyme-linked immunosorbent assay (ELISA) was used to quantify γH2AX, a molecular marker for DSBs, in the blood of mice after a 6-hour exposure to magnetic resonance imaging (MRI). Fourteen CF-1 female mice were separated into 4 experimental groups: Untreated negative control, MRI-treated, MRI-Control, and exposed to ionizing radiation positive control. Untreated negative control was used as a baseline for ELISA to quantify γH2AX. MRI-treated consisted of a 6-hour continuous magnetic resonance imaging (MRI) echo planar imaging (EPI) sequence with a slew rate of 192 mT/m/s constituting a significantly longer imaging time than routine clinical imaging. MRI-control mice were maintained under the same conditions outside the MRI scanner for 6-hours. Mice in the irradiation group served as a positive control of DSBs and were exposed to either 2 Gy, 5 Gy or 10 Gy of ionizing radiation. DSBs in the blood lymphocytes from the treatment groups were analyzed using the γH2AX ELISA and compared. Total protein concentration in lysates was determined for each blood sample and averaged 1 ± 0.35 mg/mL. Irradiated positive controls were used to test radiation dose-dependency of the γH2AX ELISA assay where a linear dependency on radiation exposure was observed (r<sup>2</sup> = 0.93) between untreated and irradiated samples. Mean and standard error mean of γH2AX formation were calculated and compared between each treatment group. Repeated measures 1-way ANOVA showed statistically significant differences between the means of irradiated controls and both the MRI-control and MRI-treated groups. There was no statistically significant difference between the MRI-treated samples and the MRI-control groups. Our results show that long MRI exposure at a high slew rate did not cause increased levels of γH2AX when compa
