Objective： To explore and investigate the selection of effective antisense oligodeoxynuleotides with the help of computer and RNAstructure folding software. Methods： Bcl-2 gene was used as the target gene and five a...Objective： To explore and investigate the selection of effective antisense oligodeoxynuleotides with the help of computer and RNAstructure folding software. Methods： Bcl-2 gene was used as the target gene and five antisense oligodeoxynuleotides were designed to be bound to Bcl-2 mRNA optimal secondary structure regions that were predicted free from intramolecular fold or instability of free energy. The five antisense oligodeoxynucleotides were studied with experimental assay of leukemia cells, including cell grow assay with tropan blue exclusion, expression of Bcl-2 protein detected with immunochemistry and flowcytometry, Bcl-2 mRNA content detected with RT-PCR technique, as well as apoptosis observed and determined with morphonological method, electrophoresis and flowcytometry. Results： The results showed that two of the five antisense oligodeoxynucleotides were effective antisense oligodeoxynucleotides, which were able to inhibit cell growth in leukemia, to decrease the level of Bcl-2 mRNA and protein, to induce apoptosis of leukemia cells significantly. Conclusion： The computational prediction of antisense efficacy is faster than other methods and more efficient, which can potentially speed the development of sequences for both research and clinical applications.展开更多
AIM： To study the effect of H2 gas on liver injury in massive hepatectomy using the Intermittent Pringle maneuver in swine. METHODS： Male Bama pigs （n = 14） treated with ketamine hydrochloride and Sumianxin Ⅱ as ...AIM： To study the effect of H2 gas on liver injury in massive hepatectomy using the Intermittent Pringle maneuver in swine. METHODS： Male Bama pigs （n = 14） treated with ketamine hydrochloride and Sumianxin Ⅱ as induc- tion drugs followed by inhalation anesthesia with 2% isoflurane, underwent 70% hepatotectomy with loss of bleeding less than 50 mL, and with hepatic pedicle occlusion for 20 min, were divided into two groups： Hydrogen-group （n = 7）, the pigs with inhalation of 2% hydrogen by the tracheal intubation during major hepa- totectomy; Contrast-group （n= 7）, underwent 70% hepatotectomy without inhalation of hydrogen. Hemo- dynamic changes and plasma concentrations of alanine aminotransferase （ALT）, aspartate aminotransferase （AST）, hyaluronic acid （HA）, tumor necrosis factor-α （TNF-α）, interleukin-6 （IL-6）, and malondialdehyde （MDA） in liver tissue were measured at pre-operation, post-hepatotectomy （PH） 1 h and 3 h. The apoptosis and proliferating cell nuclear antigen （PCNA） expres- sion in liver remnant were evaluated at PH 3 h. Then we compared the two groups by these marks to evalu- ate the effect of the hydrogen in the liver injury during major hepatotectomy with the Pringle Maneuver in the swine. RESULTS： There were no significant differences in body weight, blood loss and removal liver weight be- tween the two groups. There was no significant differ- ence in changes of portal vein pressure between two groups at pre-operation, PH 30 min, but in hydrogen gas treated-group it slightly decrease and lower than its in Contrast-group at PH 3 h, although there were no significant difference （P = 0.655）. ALT and AST in Hydrogen-group was significantly lower comparing to Contrast-group （P = 0.036, P = 0.011, vs P = 0.032, P = 0.013） at PH 1 h and 3 h, although the two groups all increased. The MDA level increased between the two group at PH i h and 3 h. In the hydrogen gas treated- group, the MDA level was not significantly significant at pre-operation and significantly low at PH 1 h and 3 h comparing to Contrast-group （P = 0.0005, P = 0.0004）. In Hydrogen-group, the HA level was also significantly low to Contrast-group （P = 0.0005, P = 0.0005） al- though the two groups all increased at PH 1 h and 3 h. The expression of cluster of differentiation molecule 31 molecules Hydrogen-group was low to Contrast-group. However, PCNA index （%） was not statistically signifi- cant between the two groups （P = 0.802）. Micropho- tometric evaluation of apoptotic index （AI） in terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-stained tissue after hepatotectomy for 3h, the AI% level in the hydrogen was significantly low to Contrast-group （P = 0.012）. There were no significant difference between Hydrogen-group and Contrast- group at pre-operation （P = 0.653, P = 0.423）, but after massive hepatotectomy, the TNF-α and IL-6 levels increase, and its in Hydrogen-group was significantly low compared with Contrast-group （P = 0.022, P = 0.013, vs P = 0.016, P= 0.012）, respectively. Hydro- gen-gas inhalation reduce levels of these markers and relieved morphological liver injury and apoptosis.CONCLUSION： H2 gas attenuates markedly ischemia and portal hyperperfusion injury in pigs with massive hepatotectomy, possibly by the reduction of inflamma- tion and oxidative stress, maybe a potential agent for treatment in clinic.展开更多
Recognition of DNA damage is a critical step for DNA damage-mediated cellular response. XPC is an important DNA damage recognition protein involved in nucleotide excision repair (NER). We have studied the XPC protein ...Recognition of DNA damage is a critical step for DNA damage-mediated cellular response. XPC is an important DNA damage recognition protein involved in nucleotide excision repair (NER). We have studied the XPC protein in cisplatin DNA damaging treatment-mediated cellular response. Comparison of the microarray data from both normal and XPCdefective human fibroblasts identified 861 XPC-responsive genes in the cisplatin treatment (with minimum fold change≥1.5).The cell cycle and cell proliferation-related genes are the most affected genes by the XPC defect in the treatment. Many other cellular function genes, especially the DNA repair and signal transduction-related genes, were also affected by the XPC defect in the treatment. To validate the microarray data, the transcription levels of some microarray-identified genes were also determined by an RT-PCR based real time PCR assay. The real time PCR results are consistent with the microarray data for most of the tested genes, indicating the reliability of the microarray data. To further validate the microarray data, the cisplatin treatment-mediated caspase-3 activation was also determined. The Western blot hybridization results indicate that the XPC defect greatly attenuates the cisplatin treatment-mediated Caspase-3 activation. We elucidated the role of p53 protein in the XPC protein DNA damage recognition-mediated signaling process. The XPC defect reduces the cisplatin treatment-mediated p53 response. These results suggest that the XPC protein plays an important role in the cisplatin treatment-mediated cellular response. It may also suggest a possible mechanism of cancer cell drug resistance.展开更多
Single-strand breaks （SSBs） can occur in cells either directly, or indirectly following initiation of base excision repair （BER）. SSBs generally have blocked termini lacking the conventional 5＇-phosphate and 3＇-...Single-strand breaks （SSBs） can occur in cells either directly, or indirectly following initiation of base excision repair （BER）. SSBs generally have blocked termini lacking the conventional 5＇-phosphate and 3＇-hydroxyl groups and require further processing prior to DNA synthesis and ligation. XRCC1 is devoid of any known enzymatic activity, but it can physically interact with other proteins involved in all stages of the overlapping SSB repair and BER pathways, including those that conduct the rate-limiting end-tailoring, and in many cases can stimulate their enzymatic activities. XRCC1^-/- mouse fibroblasts are most hypersensitive to agents that produce DNA lesions repaired by monofunctional glycosylase-initiated BER and that result in formation of indirect SSBs. A requirement for the deoxyribose phosphate lyase activity of DNA polymerase β （pol β） is specific to this pathway, whereas pol β is implicated in gap-filling during repair of many types of SSBs. Elevated levels of strand breaks, and diminished repair, have been demonstrated in MMS- treated XRCC1^-/-, and to a lesser extent in pol β^-/- cell lines, compared with wild-type cells. Thus a strong correlation is observed between cellular sensitivity to MMS and the ability of cells to repair MMS-induced damage. Exposure of wild-type and polβ^-/- cells to an inhibitor of PARP activity dramatically potentiates MMS-induced cytotoxicity. XRCC1^-/- cells are also sensitized by PARP inhibition demonstrating that PARP-mediated poly（ADP-ribosyl）ation plays a role in modulation of cytotoxicity beyond recruitment of XRCC 1 to sites of DNA damage.展开更多
A fundamental question in DNA repair is how a lesion is detected when embedded in millions to billions of normal base pairs. Extensive structural and functional studies reveal atomic details of DNA repair protein and ...A fundamental question in DNA repair is how a lesion is detected when embedded in millions to billions of normal base pairs. Extensive structural and functional studies reveal atomic details of DNA repair protein and nucleic acid interactions. This review summarizes seemingly diverse structural motifs used in lesion recognition and suggests a general mechanism to recognize DNA lesion by the poor base stacking. After initial recognition of this shared structural feature of lesions, different DNA repair pathways use unique verification mechanisms to ensure correct lesion identification and removal.展开更多
DNA damage can, but does not always, induce cell death. While several pathways linking DNA damage signals to mitochondria-dependent and -independent death machineries have been elucidated, the connectivity of these pa...DNA damage can, but does not always, induce cell death. While several pathways linking DNA damage signals to mitochondria-dependent and -independent death machineries have been elucidated, the connectivity of these pathways is subject to regulation by multiple other factors that are not well understood. We have proposed two conceptual models to explain the delayed and variable cell death response to DNA damage： integrative surveillance versus autonomous pathways. In this review, we discuss how these two models may explain the in vivo regulation of cell death induced by ionizing radiation （IR） in the developing central nervous system, where the death response is regulated by radiation dose, cell cycle status and neuronal development.展开更多
Most current knowledge about DNA polymerase zeta （pol ζ） comes from studies of the enzyme in the budding yeast Saccharomyces cerevisiae, where pol ζ consists of a complex of the catalytic subunit Rev3 with Rev7, w...Most current knowledge about DNA polymerase zeta （pol ζ） comes from studies of the enzyme in the budding yeast Saccharomyces cerevisiae, where pol ζ consists of a complex of the catalytic subunit Rev3 with Rev7, which associates with Revl. Most spontaneous and induced mutagenesis in yeast is dependent on these gene products, and yeast pol can mediate translesion DNA synthesis past some adducts in DNA templates. Study of the homologous gene products in higher eukaryotes is in a relatively early stage, but additional functions for the eukaryotic proteins are already apparent. Suppression of vertebrate REV3L function not only reduces induced point mutagenesis but also causes larger-scale genome instability by raising the frequency of spontaneous chromosome translocations. Disruption of Rev3L function is tolerated in Drosophila, Arabidopsis, and in vertebrate cell lines under some conditions, but is incompatible with mouse embryonic development. Functions for REV3L and REV7（MAD2B） in higher eukaryotes have been suggested not only in translesion DNA synthesis but also in some forms of homologous recombination, repair of interstrand DNA crosslinks, somatic hypermutation of immunoglobulin genes and cell-cycle control. This review discusses recent developments in these areas.展开更多
DNA replication is tightly regulated during the S phase of the cell cycle, and the activation of the intra-S-phase checkpoint due to DNA damage usually results in arrest of DNA synthesis. However, the molecular detail...DNA replication is tightly regulated during the S phase of the cell cycle, and the activation of the intra-S-phase checkpoint due to DNA damage usually results in arrest of DNA synthesis. However, the molecular details about the correlation between the checkpoint and regulation of DNA replication are still unclear. To investigate the connections between DNA replication and DNA damage checkpoint, a DNA-damage reagent, tripchlorolide, was applied to CHO (Chinese ovary hamster) cells at early- or middle-stages of the S phase. The early-S-phase treatment with TC significantly delayed the progression of the S phase and caused the phosphorylation of the Chkl checkpoint protein, whereas the middle-S-phase treatment only slightly slowed down the progression of the S phase. Furthermore, the analysis of DNA replication patterns revealed that replication pattern II was greatly prolonged in the cells treated with the drug during the early-S phase, whereas the late-replication patterns of these cells were hardly detected, suggesting that the activation of the intra-S-phase checkpoint inhibits the late-origin firing of DNA replication. We conclude that cells at different stages of the S phase are differentially sensitive to the DNA-damage reagent, and the activation of the intra-S phase checkpoint blocks the DNA replication progression in the late stage of S phase.展开更多
Objective: To study the roles of different truncated hepatitis C virus (HCV) core proteins (CORE) in the pathogenesis of HCV persistent infection and hepatocellular carcinoma (HCC) and to assess intracellular localiza...Objective: To study the roles of different truncated hepatitis C virus (HCV) core proteins (CORE) in the pathogenesis of HCV persistent infection and hepatocellular carcinoma (HCC) and to assess intracellular localization in transiently transfected cells. Methods: Seven truncated CORE-GFP (green fluorescent protein) fusion protein expression plasmids were constructed, which contained HCV CORE sequences derived from tumor tissues (BT) and non-tumor tissues (BNT) from one patient infected with HCV. Amino acid (aa) lengths were BT: 1?172 aa, 1?126 aa, 1?58 aa, 59?126 aa, 127?172 aa; BNT: 1?172 aa and C191: 1?172 aa respectively. Subcellular localization of CORE-GFP was analyzed by con-focal laser scanning microscope. Apoptosis and necrosis were quantified by flow cytometry. Results: Different truncated CORE-GFP localized mainly in the cytoplasm, but nuclear staining was also observed. HCV CORE could induce apoptosis and necrosis, and different truncated COREs could induce cell apoptosis and necrosis at different levels. Among the same length 1?172 aa of BT, BNT and C191, the cell apoptosis and necrosis percentage of BT is highest, and C191 is the lowest (BT>BNT>C191). To the different fragment COREs of BT, N-terminal of CORE induced apoptosis and necrosis higher, compared with that of C-terminal (1?172 aa>1?126 aa>1?58 aa>127?172 aa>59?126 aa). Conclusion: These results suggest HCV CORE could induce apoptosis and necrosis of cells, which might play an important role in the pathogenesis of HCV persistent infection and HCC and the different CORE domains of dif- ferent HCV quasi-species might have some difference in their pathogenesis.展开更多
This report gives a better emphasis on the role of targeted effectors (e.g. a combination of 5-FC with CD-NSPCs as compared to the application of NSPCs alone) and how such delivery of pro-drug activating enzymes and o...This report gives a better emphasis on the role of targeted effectors (e.g. a combination of 5-FC with CD-NSPCs as compared to the application of NSPCs alone) and how such delivery of pro-drug activating enzymes and other tumor-killing substances may overcome melanocytic defence system, interact with and promote the host defence and immune response modulations not only in melanoma but, potentially, in other highly-metastatic cancers.展开更多
AIM： To elucidate the role of neuropilin-1 （Nrp-1） and semaphorin 3A （Sema3A） in sinusoidal remodeling dur- ing liver regeneration in rats. METHODS： Male Wistar/ST rats at 7 wk of age, weigh- ing about 200 g, we...AIM： To elucidate the role of neuropilin-1 （Nrp-1） and semaphorin 3A （Sema3A） in sinusoidal remodeling dur- ing liver regeneration in rats. METHODS： Male Wistar/ST rats at 7 wk of age, weigh- ing about 200 g, were used for all animal experiments. In vivo, at 24, 48, 72, 96, 144 and 192 h after two- thirds partial hepatectomy （PHx）, the remnant livers were removed. Liver tissues were immunohistochemi- cally stained for Nrp-1, Sema3A and SE-1, a liver sinu- soidal endothelial cell （SEC） marker. Total RNA of the liver tissue was extracted and reversely transcribed into cDNA. The mRNA expression of Sema3A was ana- lyzed by quantitative real-time polymerase chain reac- tion and normalized to that of ribosomal protein $18. In vitro, SECs were isolated from rat liver and cultured in endothelial growth medium containing 20 ng/mL vascular endothelial cell growth factor. Migration of SECs in primary culture was assessed by cell transwell assay with or without recombinant Sema3A. Apoptotic cells were determined by a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling method. RESULTS： In vitro, immunohistochemistry study re- vealed that Sema3A and Nrp-1 were constitutively ex- pressed in hepatocytes and SECs, respectively, in normal rat liver tissues. Nrp-1 expression in SECs was quantified by the percentage of immunostained area with anti- Nrp-1 antibody in relation to the area stained with SE-1. Between 24 h and 96 h following resection of liver, Nrp-1 expression in SECs was transiently increased. Compared with the baseline （5.2% ± 0.1%）, Nrp-1 expression in SECs significantly increased at 24 h （17.3% ± 0.7%, P 〈 0.05）, 48 h （39.1% ± 0.6%, P 〈 0.01）, 72 h （46.9% ± 4.5%, P 〈 0.01） and 96 h （29.9% ±3.8%, P 〈 0.01） after PHx, then returned to the basal level at termination of liver regeneration. Interestingly, the expression of Sema3A was inversely associated with that of Nrp-1 in liver after PHx. Sema3A mRNA expres- sion was significantly reduced by about 75% over the period 24-144 h after PHx （P 〈 0.05）, and returned to basal levels at 192 h after PHx. In vitro, SECs isolated from rats after PHx （PHx-SECs） were observed to mi- grate to the lower chamber of the cell transwell system after incubation for 24 h, but not cells from normal rats （CONT-SECs）, indicating that mobility of PHx-SECs increases as compared with that of CONT-SECs. More- over, recombinant Sema3A significantly attenuated mi- gration in PHx-SECs in primary culture （vehicle-treated 100% ± 7.9% vs Sema3A-treated 42.6% ± 5.4%, P 〈 0.01）, but not in CONT-SECs. Compared with CONT- SECs, the apoptotic rate of PHx-SECs decreased by 78.3% （P 〈 0.05）. There was no difference in apopto- sis between CONT-SECs that were treated with vehicle and Sema3A. However, in PHx-SECs, apoptosis was induced by the presence of 5 nmol Sema3A for 24 h （vehicle-treated 21.7%±7.6% vs Sema3A-treated 104.3% ± 8.9%, P 〈 0.05）. In addition, immunohisto- chemistry confirmed the increased expression of Nrp-1 in PHx-SECs, while it was noted to a lesser extent in CONT-SECs. CONCLUSION： The interplay of Nrp-1 and Sema3A shown in our results may lead to a better understand- ing of interaction between sinusoidal remodeling and SECs during liver regeneration.展开更多
Hesperidin is a bioflavonoid abundantly found in citrus fruits and displays chemoprotective effects against DNA （deoxyribonucleic acid） damage, however there are few reports about hesperidin effects against cisplati...Hesperidin is a bioflavonoid abundantly found in citrus fruits and displays chemoprotective effects against DNA （deoxyribonucleic acid） damage, however there are few reports about hesperidin effects against cisplatin-DNA damage induction. The aim of this work was to evaluate hesperidin antimutagenicity against cisptatin-DNA damage. （1） The antimutagenicity of hesperidin was assayed by bone marrow of mice in vivo using the micronucleus test. Hesperidin pre-treatment protocol reduced the frequency of MNPCE （micronucleated polychromatic erythrocytes） and the dose of 100 mg·kg-1 was highest efficiency, with 65.24% of damage reduction. In the simultaneous treatment protocol, the dose of 200 mg·kg-1 exhibited a more effective reduction of MNPCE, with 94.01% of damage reduction. （2） Hesperidin was also effective in reducing the MNPCE frequency in the post-treatment protocol for all doses, with 77.48%, 82.13% and 90.08% of damage reduction at the doses of 100, 200 and 400 mg·kg-1, respectively. From the study, it can be concluded that hesperidin was able to promote the reduction of micronuclei frequency and DNA damage induced by cisplatin. Hesperidin is a powerful antioxidant compound and its chemoprotective effects on DNA may occur due to its association with the antioxidant cell system which is responsible for eliminate free radicals generated by chemical harmful to DNA.展开更多
DNA damage is a relatively common event in eukaryotic cell and may lead to genetic mutation and even cancer. DNA damage induces cellular responses that enable the cell either to repair the damaged DNA or cope with the...DNA damage is a relatively common event in eukaryotic cell and may lead to genetic mutation and even cancer. DNA damage induces cellular responses that enable the cell either to repair the damaged DNA or cope with the damage in an appropriate way. Histone proteins are also the fundamental building blocks of eukaryotic chromatin besides DNA, and many types of post-translational modifications often occur on tails of histones. Although the function of these modifications has remained elusive, there is ever-growing studies suggest that histone modifications play vital roles in several chromatin-based processes, such as DNA damage response. In this review, we will discuss the main histone modifications, and their functions in DNA damage response.展开更多
文摘Objective： To explore and investigate the selection of effective antisense oligodeoxynuleotides with the help of computer and RNAstructure folding software. Methods： Bcl-2 gene was used as the target gene and five antisense oligodeoxynuleotides were designed to be bound to Bcl-2 mRNA optimal secondary structure regions that were predicted free from intramolecular fold or instability of free energy. The five antisense oligodeoxynucleotides were studied with experimental assay of leukemia cells, including cell grow assay with tropan blue exclusion, expression of Bcl-2 protein detected with immunochemistry and flowcytometry, Bcl-2 mRNA content detected with RT-PCR technique, as well as apoptosis observed and determined with morphonological method, electrophoresis and flowcytometry. Results： The results showed that two of the five antisense oligodeoxynucleotides were effective antisense oligodeoxynucleotides, which were able to inhibit cell growth in leukemia, to decrease the level of Bcl-2 mRNA and protein, to induce apoptosis of leukemia cells significantly. Conclusion： The computational prediction of antisense efficacy is faster than other methods and more efficient, which can potentially speed the development of sequences for both research and clinical applications.
文摘AIM： To study the effect of H2 gas on liver injury in massive hepatectomy using the Intermittent Pringle maneuver in swine. METHODS： Male Bama pigs （n = 14） treated with ketamine hydrochloride and Sumianxin Ⅱ as induc- tion drugs followed by inhalation anesthesia with 2% isoflurane, underwent 70% hepatotectomy with loss of bleeding less than 50 mL, and with hepatic pedicle occlusion for 20 min, were divided into two groups： Hydrogen-group （n = 7）, the pigs with inhalation of 2% hydrogen by the tracheal intubation during major hepa- totectomy; Contrast-group （n= 7）, underwent 70% hepatotectomy without inhalation of hydrogen. Hemo- dynamic changes and plasma concentrations of alanine aminotransferase （ALT）, aspartate aminotransferase （AST）, hyaluronic acid （HA）, tumor necrosis factor-α （TNF-α）, interleukin-6 （IL-6）, and malondialdehyde （MDA） in liver tissue were measured at pre-operation, post-hepatotectomy （PH） 1 h and 3 h. The apoptosis and proliferating cell nuclear antigen （PCNA） expres- sion in liver remnant were evaluated at PH 3 h. Then we compared the two groups by these marks to evalu- ate the effect of the hydrogen in the liver injury during major hepatotectomy with the Pringle Maneuver in the swine. RESULTS： There were no significant differences in body weight, blood loss and removal liver weight be- tween the two groups. There was no significant differ- ence in changes of portal vein pressure between two groups at pre-operation, PH 30 min, but in hydrogen gas treated-group it slightly decrease and lower than its in Contrast-group at PH 3 h, although there were no significant difference （P = 0.655）. ALT and AST in Hydrogen-group was significantly lower comparing to Contrast-group （P = 0.036, P = 0.011, vs P = 0.032, P = 0.013） at PH 1 h and 3 h, although the two groups all increased. The MDA level increased between the two group at PH i h and 3 h. In the hydrogen gas treated- group, the MDA level was not significantly significant at pre-operation and significantly low at PH 1 h and 3 h comparing to Contrast-group （P = 0.0005, P = 0.0004）. In Hydrogen-group, the HA level was also significantly low to Contrast-group （P = 0.0005, P = 0.0005） al- though the two groups all increased at PH 1 h and 3 h. The expression of cluster of differentiation molecule 31 molecules Hydrogen-group was low to Contrast-group. However, PCNA index （%） was not statistically signifi- cant between the two groups （P = 0.802）. Micropho- tometric evaluation of apoptotic index （AI） in terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-stained tissue after hepatotectomy for 3h, the AI% level in the hydrogen was significantly low to Contrast-group （P = 0.012）. There were no significant difference between Hydrogen-group and Contrast- group at pre-operation （P = 0.653, P = 0.423）, but after massive hepatotectomy, the TNF-α and IL-6 levels increase, and its in Hydrogen-group was significantly low compared with Contrast-group （P = 0.022, P = 0.013, vs P = 0.016, P= 0.012）, respectively. Hydro- gen-gas inhalation reduce levels of these markers and relieved morphological liver injury and apoptosis.CONCLUSION： H2 gas attenuates markedly ischemia and portal hyperperfusion injury in pigs with massive hepatotectomy, possibly by the reduction of inflamma- tion and oxidative stress, maybe a potential agent for treatment in clinic.
文摘Recognition of DNA damage is a critical step for DNA damage-mediated cellular response. XPC is an important DNA damage recognition protein involved in nucleotide excision repair (NER). We have studied the XPC protein in cisplatin DNA damaging treatment-mediated cellular response. Comparison of the microarray data from both normal and XPCdefective human fibroblasts identified 861 XPC-responsive genes in the cisplatin treatment (with minimum fold change≥1.5).The cell cycle and cell proliferation-related genes are the most affected genes by the XPC defect in the treatment. Many other cellular function genes, especially the DNA repair and signal transduction-related genes, were also affected by the XPC defect in the treatment. To validate the microarray data, the transcription levels of some microarray-identified genes were also determined by an RT-PCR based real time PCR assay. The real time PCR results are consistent with the microarray data for most of the tested genes, indicating the reliability of the microarray data. To further validate the microarray data, the cisplatin treatment-mediated caspase-3 activation was also determined. The Western blot hybridization results indicate that the XPC defect greatly attenuates the cisplatin treatment-mediated Caspase-3 activation. We elucidated the role of p53 protein in the XPC protein DNA damage recognition-mediated signaling process. The XPC defect reduces the cisplatin treatment-mediated p53 response. These results suggest that the XPC protein plays an important role in the cisplatin treatment-mediated cellular response. It may also suggest a possible mechanism of cancer cell drug resistance.
文摘Single-strand breaks （SSBs） can occur in cells either directly, or indirectly following initiation of base excision repair （BER）. SSBs generally have blocked termini lacking the conventional 5＇-phosphate and 3＇-hydroxyl groups and require further processing prior to DNA synthesis and ligation. XRCC1 is devoid of any known enzymatic activity, but it can physically interact with other proteins involved in all stages of the overlapping SSB repair and BER pathways, including those that conduct the rate-limiting end-tailoring, and in many cases can stimulate their enzymatic activities. XRCC1^-/- mouse fibroblasts are most hypersensitive to agents that produce DNA lesions repaired by monofunctional glycosylase-initiated BER and that result in formation of indirect SSBs. A requirement for the deoxyribose phosphate lyase activity of DNA polymerase β （pol β） is specific to this pathway, whereas pol β is implicated in gap-filling during repair of many types of SSBs. Elevated levels of strand breaks, and diminished repair, have been demonstrated in MMS- treated XRCC1^-/-, and to a lesser extent in pol β^-/- cell lines, compared with wild-type cells. Thus a strong correlation is observed between cellular sensitivity to MMS and the ability of cells to repair MMS-induced damage. Exposure of wild-type and polβ^-/- cells to an inhibitor of PARP activity dramatically potentiates MMS-induced cytotoxicity. XRCC1^-/- cells are also sensitized by PARP inhibition demonstrating that PARP-mediated poly（ADP-ribosyl）ation plays a role in modulation of cytotoxicity beyond recruitment of XRCC 1 to sites of DNA damage.
文摘A fundamental question in DNA repair is how a lesion is detected when embedded in millions to billions of normal base pairs. Extensive structural and functional studies reveal atomic details of DNA repair protein and nucleic acid interactions. This review summarizes seemingly diverse structural motifs used in lesion recognition and suggests a general mechanism to recognize DNA lesion by the poor base stacking. After initial recognition of this shared structural feature of lesions, different DNA repair pathways use unique verification mechanisms to ensure correct lesion identification and removal.
文摘DNA damage can, but does not always, induce cell death. While several pathways linking DNA damage signals to mitochondria-dependent and -independent death machineries have been elucidated, the connectivity of these pathways is subject to regulation by multiple other factors that are not well understood. We have proposed two conceptual models to explain the delayed and variable cell death response to DNA damage： integrative surveillance versus autonomous pathways. In this review, we discuss how these two models may explain the in vivo regulation of cell death induced by ionizing radiation （IR） in the developing central nervous system, where the death response is regulated by radiation dose, cell cycle status and neuronal development.
文摘Most current knowledge about DNA polymerase zeta （pol ζ） comes from studies of the enzyme in the budding yeast Saccharomyces cerevisiae, where pol ζ consists of a complex of the catalytic subunit Rev3 with Rev7, which associates with Revl. Most spontaneous and induced mutagenesis in yeast is dependent on these gene products, and yeast pol can mediate translesion DNA synthesis past some adducts in DNA templates. Study of the homologous gene products in higher eukaryotes is in a relatively early stage, but additional functions for the eukaryotic proteins are already apparent. Suppression of vertebrate REV3L function not only reduces induced point mutagenesis but also causes larger-scale genome instability by raising the frequency of spontaneous chromosome translocations. Disruption of Rev3L function is tolerated in Drosophila, Arabidopsis, and in vertebrate cell lines under some conditions, but is incompatible with mouse embryonic development. Functions for REV3L and REV7（MAD2B） in higher eukaryotes have been suggested not only in translesion DNA synthesis but also in some forms of homologous recombination, repair of interstrand DNA crosslinks, somatic hypermutation of immunoglobulin genes and cell-cycle control. This review discusses recent developments in these areas.
基金This work was supported by a grant from the National Natural Science Foundation of China(No.30230110)a special grant from the Major State Basic Research Pro-gram of China(No.G1999053901)a grant from the Chinese Academy of Sciences(No.KSCX2-SW-203)to Jia Rui WU.
文摘DNA replication is tightly regulated during the S phase of the cell cycle, and the activation of the intra-S-phase checkpoint due to DNA damage usually results in arrest of DNA synthesis. However, the molecular details about the correlation between the checkpoint and regulation of DNA replication are still unclear. To investigate the connections between DNA replication and DNA damage checkpoint, a DNA-damage reagent, tripchlorolide, was applied to CHO (Chinese ovary hamster) cells at early- or middle-stages of the S phase. The early-S-phase treatment with TC significantly delayed the progression of the S phase and caused the phosphorylation of the Chkl checkpoint protein, whereas the middle-S-phase treatment only slightly slowed down the progression of the S phase. Furthermore, the analysis of DNA replication patterns revealed that replication pattern II was greatly prolonged in the cells treated with the drug during the early-S phase, whereas the late-replication patterns of these cells were hardly detected, suggesting that the activation of the intra-S-phase checkpoint inhibits the late-origin firing of DNA replication. We conclude that cells at different stages of the S phase are differentially sensitive to the DNA-damage reagent, and the activation of the intra-S phase checkpoint blocks the DNA replication progression in the late stage of S phase.
基金Project (No. 2001BA705B06) supported by a grant from the National Key Technologies R&D program (10th Five-Year Plan) of China
文摘Objective: To study the roles of different truncated hepatitis C virus (HCV) core proteins (CORE) in the pathogenesis of HCV persistent infection and hepatocellular carcinoma (HCC) and to assess intracellular localization in transiently transfected cells. Methods: Seven truncated CORE-GFP (green fluorescent protein) fusion protein expression plasmids were constructed, which contained HCV CORE sequences derived from tumor tissues (BT) and non-tumor tissues (BNT) from one patient infected with HCV. Amino acid (aa) lengths were BT: 1?172 aa, 1?126 aa, 1?58 aa, 59?126 aa, 127?172 aa; BNT: 1?172 aa and C191: 1?172 aa respectively. Subcellular localization of CORE-GFP was analyzed by con-focal laser scanning microscope. Apoptosis and necrosis were quantified by flow cytometry. Results: Different truncated CORE-GFP localized mainly in the cytoplasm, but nuclear staining was also observed. HCV CORE could induce apoptosis and necrosis, and different truncated COREs could induce cell apoptosis and necrosis at different levels. Among the same length 1?172 aa of BT, BNT and C191, the cell apoptosis and necrosis percentage of BT is highest, and C191 is the lowest (BT>BNT>C191). To the different fragment COREs of BT, N-terminal of CORE induced apoptosis and necrosis higher, compared with that of C-terminal (1?172 aa>1?126 aa>1?58 aa>127?172 aa>59?126 aa). Conclusion: These results suggest HCV CORE could induce apoptosis and necrosis of cells, which might play an important role in the pathogenesis of HCV persistent infection and HCC and the different CORE domains of dif- ferent HCV quasi-species might have some difference in their pathogenesis.
文摘This report gives a better emphasis on the role of targeted effectors (e.g. a combination of 5-FC with CD-NSPCs as compared to the application of NSPCs alone) and how such delivery of pro-drug activating enzymes and other tumor-killing substances may overcome melanocytic defence system, interact with and promote the host defence and immune response modulations not only in melanoma but, potentially, in other highly-metastatic cancers.
基金Supported by A Grant-in-aid for Young Scientists from Japan Society for the Promotion of Science,No.22790671
文摘AIM： To elucidate the role of neuropilin-1 （Nrp-1） and semaphorin 3A （Sema3A） in sinusoidal remodeling dur- ing liver regeneration in rats. METHODS： Male Wistar/ST rats at 7 wk of age, weigh- ing about 200 g, were used for all animal experiments. In vivo, at 24, 48, 72, 96, 144 and 192 h after two- thirds partial hepatectomy （PHx）, the remnant livers were removed. Liver tissues were immunohistochemi- cally stained for Nrp-1, Sema3A and SE-1, a liver sinu- soidal endothelial cell （SEC） marker. Total RNA of the liver tissue was extracted and reversely transcribed into cDNA. The mRNA expression of Sema3A was ana- lyzed by quantitative real-time polymerase chain reac- tion and normalized to that of ribosomal protein $18. In vitro, SECs were isolated from rat liver and cultured in endothelial growth medium containing 20 ng/mL vascular endothelial cell growth factor. Migration of SECs in primary culture was assessed by cell transwell assay with or without recombinant Sema3A. Apoptotic cells were determined by a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling method. RESULTS： In vitro, immunohistochemistry study re- vealed that Sema3A and Nrp-1 were constitutively ex- pressed in hepatocytes and SECs, respectively, in normal rat liver tissues. Nrp-1 expression in SECs was quantified by the percentage of immunostained area with anti- Nrp-1 antibody in relation to the area stained with SE-1. Between 24 h and 96 h following resection of liver, Nrp-1 expression in SECs was transiently increased. Compared with the baseline （5.2% ± 0.1%）, Nrp-1 expression in SECs significantly increased at 24 h （17.3% ± 0.7%, P 〈 0.05）, 48 h （39.1% ± 0.6%, P 〈 0.01）, 72 h （46.9% ± 4.5%, P 〈 0.01） and 96 h （29.9% ±3.8%, P 〈 0.01） after PHx, then returned to the basal level at termination of liver regeneration. Interestingly, the expression of Sema3A was inversely associated with that of Nrp-1 in liver after PHx. Sema3A mRNA expres- sion was significantly reduced by about 75% over the period 24-144 h after PHx （P 〈 0.05）, and returned to basal levels at 192 h after PHx. In vitro, SECs isolated from rats after PHx （PHx-SECs） were observed to mi- grate to the lower chamber of the cell transwell system after incubation for 24 h, but not cells from normal rats （CONT-SECs）, indicating that mobility of PHx-SECs increases as compared with that of CONT-SECs. More- over, recombinant Sema3A significantly attenuated mi- gration in PHx-SECs in primary culture （vehicle-treated 100% ± 7.9% vs Sema3A-treated 42.6% ± 5.4%, P 〈 0.01）, but not in CONT-SECs. Compared with CONT- SECs, the apoptotic rate of PHx-SECs decreased by 78.3% （P 〈 0.05）. There was no difference in apopto- sis between CONT-SECs that were treated with vehicle and Sema3A. However, in PHx-SECs, apoptosis was induced by the presence of 5 nmol Sema3A for 24 h （vehicle-treated 21.7%±7.6% vs Sema3A-treated 104.3% ± 8.9%, P 〈 0.05）. In addition, immunohisto- chemistry confirmed the increased expression of Nrp-1 in PHx-SECs, while it was noted to a lesser extent in CONT-SECs. CONCLUSION： The interplay of Nrp-1 and Sema3A shown in our results may lead to a better understand- ing of interaction between sinusoidal remodeling and SECs during liver regeneration.
文摘Hesperidin is a bioflavonoid abundantly found in citrus fruits and displays chemoprotective effects against DNA （deoxyribonucleic acid） damage, however there are few reports about hesperidin effects against cisplatin-DNA damage induction. The aim of this work was to evaluate hesperidin antimutagenicity against cisptatin-DNA damage. （1） The antimutagenicity of hesperidin was assayed by bone marrow of mice in vivo using the micronucleus test. Hesperidin pre-treatment protocol reduced the frequency of MNPCE （micronucleated polychromatic erythrocytes） and the dose of 100 mg·kg-1 was highest efficiency, with 65.24% of damage reduction. In the simultaneous treatment protocol, the dose of 200 mg·kg-1 exhibited a more effective reduction of MNPCE, with 94.01% of damage reduction. （2） Hesperidin was also effective in reducing the MNPCE frequency in the post-treatment protocol for all doses, with 77.48%, 82.13% and 90.08% of damage reduction at the doses of 100, 200 and 400 mg·kg-1, respectively. From the study, it can be concluded that hesperidin was able to promote the reduction of micronuclei frequency and DNA damage induced by cisplatin. Hesperidin is a powerful antioxidant compound and its chemoprotective effects on DNA may occur due to its association with the antioxidant cell system which is responsible for eliminate free radicals generated by chemical harmful to DNA.
基金supported by the National Natural Science Foundation of China(8132100391319302+3 种基金31070691)Ministry of Science and Technology of China(2011CB504200)Ministry of Education of China(111 project)Peking University-Tsinghua University Center for Life Science
文摘DNA damage is a relatively common event in eukaryotic cell and may lead to genetic mutation and even cancer. DNA damage induces cellular responses that enable the cell either to repair the damaged DNA or cope with the damage in an appropriate way. Histone proteins are also the fundamental building blocks of eukaryotic chromatin besides DNA, and many types of post-translational modifications often occur on tails of histones. Although the function of these modifications has remained elusive, there is ever-growing studies suggest that histone modifications play vital roles in several chromatin-based processes, such as DNA damage response. In this review, we will discuss the main histone modifications, and their functions in DNA damage response.
