AIM： To investigate the dynamic alteration of telomerase expression during development of hepatocellular carcinoma （HCC） and its diagnostic implications in liver tissues or peripheral blood mononuclear cells for HC...AIM： To investigate the dynamic alteration of telomerase expression during development of hepatocellular carcinoma （HCC） and its diagnostic implications in liver tissues or peripheral blood mononuclear cells for HCC. METHODS： Dynamic expressions of liver telomerase during malignant transformation of hepatocytes were observed in Sprague-Dawly （SD） rats fed with 0.05% of 2-fluoenyacetamide （2-FAA）. Total RNA and telomerase were extracted from rat or human liver tissues. The telomerase activities in livers and in circulating blood were detected by a telomeric repeat amplification protocol-enzyme-linked immunosorbent assay （TRAP- ELISA）, and its diagnostic value was investigated in patients with benign or malignant liver diseases. RESULTS： The hepatoma model displayed the dynamic expression of hepatic telomerase during HCC development. The telomerase activities were consistent with liver total RNA levels （r = 0.83, P 〈 0.01） at the stages of degeneration, precancerosis, and cancerization of hepatocytes. In HCC patients, the telomerase levels in HCC tissues were significantly higher than in their adjacent non-cancerous tissues, but liver total RNA levels were lower in the former than in the latter. Although the circulating telomerase of HCC patients was abnormally expressed among patients with chronic liver diseases, the telomerase activity was a non-specific marker for HCC diagnosis, because the incidence was 15.7% in normal control, 25% in chronic hepatitis, 45.9% in liver cirrhosis, and 85.2% in HCC, respectively when absorbance value of telomerase activity was more than 0.2. If the value was over 0.6, the incidence was 60% in HCC group and 0% in any of the others （P 〈 0.01） except in two cases with liver cirrhosis. However, the combination of circulating telomerase with serum alpha-fetoprotein level could increase the positive rate and the accuracy （92.6%, 125 of 135） of HCC diagnosis. CONCLUSION： The overexpression of telomerase is associated with HCC development, and its a展开更多
The chromosomes of spinyhead croaker Collichthys lucidus（Richardson,1844） were characterized for the first time by fluorescence staining,self genomic in situ hybridization（self-GISH）,and multicolor fluorescence in...The chromosomes of spinyhead croaker Collichthys lucidus（Richardson,1844） were characterized for the first time by fluorescence staining,self genomic in situ hybridization（self-GISH）,and multicolor fluorescence in situ hybridization（FISH） with 18 SrDNA,5 SrDNA and telomeric sequence probes.The female karyotype has exclusively 24 pairs of acrocentric chromosomes（2 n=48 a,NF=48）,while the male one consists of 22 pairs of acrocentric chromosomes,2 monosomic acrocentric chromosomes and a metacentric chromosome（2 n=1 m＋46 a,NF=48）.The difference between female and male karyotypes indicates the presence of a sex chromosome of X1 X1 X2 X2/X1 X2 Y type,where Y is the unique metacentric chromosome in the male karyotype.As revealed by FISH,5 S r DNA and 18 S r DNA sites were mapped at syntenic position of the largest acrocentric chromosome（X_1）,and the short arms of the Y chromosome as well.An X_1-chromosome specific interstitial telomeric signal（ITS） was detected overlapping the 5 S r DNA sites.In addition,self-GISH revealed that the repetitive DNAs accumulated on all the putative sex chromosome.Chromosome fusion accompanied by a partial deletion in the ancestral karyotype（2 n=48 a） is hypothesized for the origin of such multiple sex chromosome system.The present study,as the first description of differentiated sex chromosome in family Sciaenidae,will give clues to the studies on the sex chromosome of other Sciaenids.展开更多
Telomeres are specialized structures at the ends of linear chromosomes that protect genome stability.The telomeric repeat-containing RNA(TERRA)that is transcribed from subtelomeric regions can invade into double-stran...Telomeres are specialized structures at the ends of linear chromosomes that protect genome stability.The telomeric repeat-containing RNA(TERRA)that is transcribed from subtelomeric regions can invade into double-stranded DNA regions and form RNA:DNA hybrid-containing structure called R-loop.In tumor cells,R-loop formation is closely linked to gene expression and the alternative lengthening of telomeres(ALT)pathway.Dysregulated R-loops can cause stalled replication forks and telomere instability.However,how R-loops are recognized and regulated,particularly at telomeres,is not well understood.We discovered that ILF3 selectively associates with telomeric R-loops and safeguards telomeres from abnormal homologous recombination.Knocking out ILF3 results in excessive R-loops at telomeres and triggers telomeric DNA damage responses.In addition,ILF3 deficiency disrupts telomere homeostasis and causes abnormalities in the ALT pathway.Using the proximity-dependent biotin identification(BioID)technology,we mapped the ILF3 interactome and discovered that ILF3 could interact with several DNA/RNA helicases,including DHX9.Importantly,ILF3 may aid in the resolution of telomeric R-loops through its interaction with DHX9.Our findings suggest that ILF3 may function as a reader of telomeric R-loops,helping to prevent abnormal homologous recombination and maintain telomere homeostasis.展开更多
AIM To investigate the role of telomeric association in the development of esophageal cancer. METHODS Using chromosome R banding technique, telomeric association of chromosome in peripheral blood lymphocytes from 1...AIM To investigate the role of telomeric association in the development of esophageal cancer. METHODS Using chromosome R banding technique, telomeric association of chromosome in peripheral blood lymphocytes from 16 untreated patients with esophageal squamous cell carcinoma were observed and 16 healthy adults served as controls. RESULTS The telomeric association frequencies of cell and chromosomes were significantly higher than those of controls (x 2=9.56,P<0.01), but its distribution on the chromosome showed no significant difference (x 2=1.01, P>0.05) between the two groups. CONCLUSION Chromosomal instability can be initiated by telomeric associations, and sequential chromosome analysis can aid the understanding of the tumor occurrence and progression.展开更多
Objective： To study the expression level of TRF1 （telomeric repeat binding factor 1） protein in human acute leukemia and relationship between expression level of TRF1 protein and telomerase, Methods： A quantitativ...Objective： To study the expression level of TRF1 （telomeric repeat binding factor 1） protein in human acute leukemia and relationship between expression level of TRF1 protein and telomerase, Methods： A quantitative Western±Blot technique was developed using anti±TRF1^33±277 monoclonal antibody and GST±TRFI purity protein as a standard to further determine the expression level of TRF1 protein in total proteins extracted from clinical specimens. Results： Bone marrow tissues of 20 acute leukemia patients were studied, 11 healthy donors＇ bone marrows were taken as a control. The expression level of TRF1 protein was significantly higher （P〈0.01） in normal bone marrow （（2.2174±0.462） μg/μl） than that of acute leukemia patients （（0.7544±0.343） μg/μl）, But there was no remarkable difference between ALL and ANLL patients （（0.6184±0.285） μg/μl vs （0.8454±0.359） μg/μl, P〉0.05）. After chemotherapy, TRFI expression level of patients with complete remission elevated （（0.7724±0.307）/μg/μl vs （1.6834±0,344）μg/μl, P〈0.01 ）, but lower than that of normal （（2.2174±0.462）/μg/μl, P〈0.01）. There was no significantly difference after chemotherapy （（0.7264±0.411） μg/μl vs （0.895±0.339） μg/μl,p〉0.05）. TRF1 expression level of patients with complete remission is higher than that of patients without complete remission （（1,683±0.344）μg/μl vs （0.895±0.339）μg/μl P〈0.01）. All samples were determined for telomerase activity. It was confirmed that the activity of telomerase in normal bone marrow was lower than that of acute leukemia patients （（0.125±0.078） μg/μl vs （0.765±0.284）μg/μl, P〈0.01）. There was no significant difference of expression level ofTRF I protein between ALL and ANLL patients （（0.897±0.290） μg/μl vs （0.677±0.268） μg/μl, P〉0.05）. After chemotherapy, telomerase activity of patients with complete remission decreased （（0.393±0.125） μg/μl）, but was展开更多
Interspecific hybridization is an important approach to improve cultivated peanut varieties. Cytological markers such as tandem repeats will facilitate alien gene introgression in peanut. Telomeric repeats have also b...Interspecific hybridization is an important approach to improve cultivated peanut varieties. Cytological markers such as tandem repeats will facilitate alien gene introgression in peanut. Telomeric repeats have also been frequently used in chromosome research. Most plant telomeric repeats are（TTTAGGG）n that are mainly distributed at the chromosome ends, although interstitial telomeric repeats（ITRs） are also commonly identified. In this study, the telomeric repeat was chromosomally localized in 10 Arachis species through sequential GISH（genomic in situ hybridization） and FISH（fluorescence in situ hybridization） combined with 4＇,6-diamidino-2-phenylindole（DAPI） staining. Six ITRs were identified such as in the centromeric region of chromosome Bi5 in Arachis ipa？nsis, pericentromeric regions of chromosomes As5 in A. stenosperma, Bho7 in A. hoehnei and Av5 in A. villosa, nucleolar organizer regions of chromosomes As3 in A. stenosperma and Adi3 in A. diogoi, subtelomeric regions of chromosomes Bho9 in A. hoehnei and Adu7 in A. duranensis, and telomeric region of chromosome Es7 in A. stenophylla. The distributions of the telomeric repeat, 5S r DNA, 45 S r DNA and DAPI staining pattern provided not only ways of distinguishing different chromosomes, but also karyotypes with a higher resolution that could be used in evolutionary genome research. The distribution of telomeric repeats, 5S r DNA and 45 S r DNA sites in this study, along with inversions detected on the long arms of chromosomes Kb10 and Bho10, indicated frequent chromosomal rearrangements during evolution of Arachis species.展开更多
Telomeres, which are found at the ends of eukaryotic chromosomes, are composed of tandem arrays of repetitive sequences and safeguard genomic stability. Previous studies have revealed that telomeric repeats are also p...Telomeres, which are found at the ends of eukaryotic chromosomes, are composed of tandem arrays of repetitive sequences and safeguard genomic stability. Previous studies have revealed that telomeric repeats are also present at internal chromosomal loci in many eukaryotes. However, the biological role of these interstitial telomeric sequences (ITSs) remains unknown. The integrity of telomeric length and chromatin structure is required for telomere stability. However, the study of these telomeric features can be impeded by the presence of ITSs. Frequently cutting restriction enzymes have been revealed to be very useful tools for the study of the length and chromatin structure of telomeres independent of the presence of ITSs.展开更多
[ Objective] To observe the expression of telomerase in antler of sika deer during growth stage and thus to provide a new line for revealing the mechanisms of development and regeneration of antlers. [Method] The upda...[ Objective] To observe the expression of telomerase in antler of sika deer during growth stage and thus to provide a new line for revealing the mechanisms of development and regeneration of antlers. [Method] The updated TRAP （Telomedc repeat amplification protocol） argentumdying method was used to detect the activity of telomerase in mesenchyme, precartilage, cartilage and ossification tissue of antler tip during the growth stage. Reverse transcription polymerase chain reaction （RT-PCR） was used to detect the expression of telomerase reverse transcriptase （TERT） in these cells. I-Result] The activity of telomerase was detected in the mesanchyme, precartilage and cartilage but not in the sclerotic tissue. The relative telomerase activity in the mesanchyme, precartilage and cartilage was 91.2, 46.4 and 13.7, respectively. In addition, the results of the expression of TERT gene also supported the detection result of telomerase activity. I-Conclmionl During growth phase, telomerase is expressed in multiplication area of deer antlers, and its activity decreases gradually with further differentiation of cells in antlers. Therefore, telomerase may play a key role in develoomant and rsoaneration of antlers.展开更多
BAC2, a rice BAC clone containing (TTTAGGG)n homologous sequences, was analyzed by Southern hybridization and DNA sequencing of its subclones. It was disclosed that there were many tandem repeated satellite DNA sequen...BAC2, a rice BAC clone containing (TTTAGGG)n homologous sequences, was analyzed by Southern hybridization and DNA sequencing of its subclones. It was disclosed that there were many tandem repeated satellite DNA sequences, called TA352, as well as simple tandem repeats consisting of TTTAGGG or its variant within the BAC2 insert. A 0. 8 kb (TTTAGGG) n-containing fragment in BAC2 was mapped in the telomere regions of at least 5 pairs of rice chromosomes by using fluorescence in situ hybridization (FISH). By RFLP analysis of low copy sequences the BAC2 clone was localized in one terminal region of chromosome 6. All the results strongly suggest that the telomeric DNA sequences of rice are TTTAGGG or its variant, and the linked satellite DNA TA352 sequences belong to telomere-associated sequences.展开更多
Objective: To investigate the significance of telomerase activity in breast carcinoma with its respect to axillary lymph node status Methods: Telomerase activity was analyzed in 88 breast carcinomas and 16 benign b...Objective: To investigate the significance of telomerase activity in breast carcinoma with its respect to axillary lymph node status Methods: Telomerase activity was analyzed in 88 breast carcinomas and 16 benign breast lesions, using polymerase chain reaction (PCR) based telomeric repeat amplification protocol (TRAP) assay Results: Telomerase activity was detected in 75 (85%) of 88 breast carcinomas (including three breast carcinomas in situ which were all positive for telomerase activity), whereas in benign breast lesions analyzed only 2(12 5%) of 16 cases were positive for telomerase activity The difference between the two groups was statistically significant ( P <0 001) Besides, telomerase activity was expressed significantly higher in node positive breast carcinoma (93%) than in node negative ones (77%) ( P <0 05) Conclusion: Our results suggest that telomerase activation plays an important role during breast carcinoma development It is possible that this enzyme may serve as an early indication of breast carcinoma展开更多
Telomeres are composed of TTAGGG repeats and located at the ends of chromosomes. Telomeres protect chromosomes from instability in mammals, including mice and humans. Repetitive TTAGGG sequences are also found at intr...Telomeres are composed of TTAGGG repeats and located at the ends of chromosomes. Telomeres protect chromosomes from instability in mammals, including mice and humans. Repetitive TTAGGG sequences are also found at intrachromosomal sites, where they are named as interstitial telomeric sequences （ITSs）. Aberrant ITSs are implicated in chromosomal instability and found in cancer cells. Interestingly, in pigs, vertebrate telomere sequences TTAGGG （vlTSs） are also localized at the centro- meric region of chromosome 6, in addition to the end of all chromosomes. Surprisingly, we found that botanic telomere se- quences, TTTAGGG （bITSs）, also localize with vITSs at the centromeric regions of pig chromosome 6 using telomere fluo- rescence in situ hybridization （FISH） and by comparisons between several species. Furthermore, the average lengths of vITSs are highly correlated with those of the terminal telomeres （TTS）. Also, pig ITSs show a high incidence of telomere doublets, suggesting that pig ITSs might be unstable and dynamic. Together, our results show that pig cells maintain the conserved te- lomere sequences that are found at the ITSs from of plants and other vertebrates. Further understanding of the function and regulation of pig ITSs may provide new clues for evolution and chromosomal instability.展开更多
Objective:To investigate the radiosensitivity of 6-thio-dG and its underlying molecular mechanisms in non-small cell lung cancer(NSCLC).Methods:H1299 and A549 NSCLC cells were pretreated with 6-thio-dG for one week an...Objective:To investigate the radiosensitivity of 6-thio-dG and its underlying molecular mechanisms in non-small cell lung cancer(NSCLC).Methods:H1299 and A549 NSCLC cells were pretreated with 6-thio-dG for one week and then exposed toγ-irradiation.Cell proliferation and survival were quantified using clonogenic assays.DNA damage was assessed using immunofluorescence forγH2AX.Telomere dysfunction-induced foci analysis was performed by the colocalization of telomere signals(FISH)andγH2AX.Telomere fusion was defined as two telomere signals merged into one at the chromosome by immuno-FISH in metaphase spreads.Proteins related to the DNA damage response were detected using Western blot analysis.Apoptosis wasanalyzed using flow cytometry and Western blot.Results:The presence of 6-thio-dG increased the radio sensitivity of H1299 and A549 cells(P<0.05),but had no effect on the normal human lung fibroblast line,MRC5.6-thio-dG pretreatment significantly reduced the clonogenic potential induced byγ-ray irradiation and aggravated genomic DNA and telomeric DNA damage(P<0.05).In addition,6-thio-dG pretreatment effectively increasedγ-ray irradiation induced telomere dysfunction(P<0.05),resulting in disruption of chromosome stability and inhibition of the ATM pathway,thereby impairing genomic DNA and telomeric DNA repair,which was closely associated with enhanced drug-mediated radiation-induced apoptosis.Conclusions:6-thio-dG increases the radiosensitivity of NSCLC by inhibiting ATM and inducing telomere dysfunction,which can potentially be used as a strategy for radiotherapy for NSCLC.展开更多
Objective： Detecting the expression and mutation of human telomeric repeat binding factor （hTRF1） in 10 malignant hematopoietic cell line cells on the base of determining its genomic structure and its four pseudoge...Objective： Detecting the expression and mutation of human telomeric repeat binding factor （hTRF1） in 10 malignant hematopoietic cell line cells on the base of determining its genomic structure and its four pseudogenes to clarify ifhTRF1 mutation is one of the factors of the activation of telomerase. Methods： hTRFlcDNA sequences were obtained from GenBank, its genome structure and pseudogenes were forecasted by BLAST and other biology information programs and then testified by sequencing. Real-time RT-PCR was used to detect the expression of h TRFlmRNA in 10 cell line cells, including myelogenous leukemia cell lines K562, HL-60, U-937, NB4, THP-I, HEL and Dami; lymphoblastic leukemia cell lines 6T-CEM, Jurkat and Raji. Telomerase activities of cells were detected by using telomeric repeat amplification （TRAP）-ELISA protocol. PCR and sequencing were used to detect mutation of each exon ofhTRF1 in 10 cell line cells. Results： hTRF1 gene, mapped to 8q13, was divided into 10 exons and spans 38.6 kb. Four processed pseudogenes ofhTRF1 located on chromosome 13, 18, 21 and X respectively, was named as ψhTRFI-13, ψhTRFI-18, ψhTRF1-21 and ψhTRFI-X respectively. All cell line cells showed positive telomerase activity. The expression of hTRF1 was significantly lower in malignant hematopoietic cell lines cells （0.0338, 0.0108-0.0749） than in normal mononuclear cells （0.0493, 0.0369-0.128） （P=0.004）. But no significant mutation was found in all exons of hTRF1 in 10 cell line cells. Four variants were found in part ofintron 1, 2 and 8 ofhTRF1. Their infection on gene function is unknown and needs further studies. Conclusion： hTRF1 mutation is probably not one of the main factors for telomerase activation in malignant hematopoietic disease.展开更多
Objective: To study the telomerase activity in human renal cell carcinoma and to evaluate the correlation with the clinicobiologic features of the neogrowth.Methods: The telomerase activity was studied by means of a m...Objective: To study the telomerase activity in human renal cell carcinoma and to evaluate the correlation with the clinicobiologic features of the neogrowth.Methods: The telomerase activity was studied by means of a modified telomeric repeat amplification protocol (TRAP) in 32 renal cell carcinoma tissues, 32 normal renal tissues and 32 paracancer tissues and its correlation with the clinicopathologic features of the tumor was evaluated.Results: Telomerase activity was strongly positive in 17, positive in 12 and negative in 3 cases of renal cell carcinoma tissues, the total positive rate being 91%. Telomerase activity was weakly positive (6%) in only 2 out of 32 samples of normal renal cortex tissues and positive in 6 paracancer tissues (19%), the difference was conspicuous (P<0.01).Conclusion: The positive rate of telomerase activity was significantly higher in renal cell carcinoma tissues and might serve as a prognostic marker for estimating the biologic characteristics of renal cell carcinoma.展开更多
G-Quadruplexes(GQs),which are formed by G-rich DNA sequences in human telomeres,have become an attractive target for cancer treatment.The ligands to stabilize the conformation of human telomeric GQs in vivo are partic...G-Quadruplexes(GQs),which are formed by G-rich DNA sequences in human telomeres,have become an attractive target for cancer treatment.The ligands to stabilize the conformation of human telomeric GQs in vivo are particularly important for structure-based ligand design and drug development targeting the noncanonical DNA structure.Here we report the conformational conversion of Tel26 induced by a naphthalene diimide(NDI)ligand in K^(+)buffer,even at cellular physiological temperature(37℃)and under mimetic cellular crowding conditions created by Ficoll 70.We provide an insight into the dynamic conversion from initial hybrid-2 GQ topology to final parallel GQ topology.These results are helpful for the design of ligands with GQ conformation regulation.展开更多
基金Supported by grants-in-aid from the Key Project of Medical Science, No. RC2003100 and grants-in-aid from the project of Department of Health, No. H200523, Jiangsu Province, China
文摘AIM： To investigate the dynamic alteration of telomerase expression during development of hepatocellular carcinoma （HCC） and its diagnostic implications in liver tissues or peripheral blood mononuclear cells for HCC. METHODS： Dynamic expressions of liver telomerase during malignant transformation of hepatocytes were observed in Sprague-Dawly （SD） rats fed with 0.05% of 2-fluoenyacetamide （2-FAA）. Total RNA and telomerase were extracted from rat or human liver tissues. The telomerase activities in livers and in circulating blood were detected by a telomeric repeat amplification protocol-enzyme-linked immunosorbent assay （TRAP- ELISA）, and its diagnostic value was investigated in patients with benign or malignant liver diseases. RESULTS： The hepatoma model displayed the dynamic expression of hepatic telomerase during HCC development. The telomerase activities were consistent with liver total RNA levels （r = 0.83, P 〈 0.01） at the stages of degeneration, precancerosis, and cancerization of hepatocytes. In HCC patients, the telomerase levels in HCC tissues were significantly higher than in their adjacent non-cancerous tissues, but liver total RNA levels were lower in the former than in the latter. Although the circulating telomerase of HCC patients was abnormally expressed among patients with chronic liver diseases, the telomerase activity was a non-specific marker for HCC diagnosis, because the incidence was 15.7% in normal control, 25% in chronic hepatitis, 45.9% in liver cirrhosis, and 85.2% in HCC, respectively when absorbance value of telomerase activity was more than 0.2. If the value was over 0.6, the incidence was 60% in HCC group and 0% in any of the others （P 〈 0.01） except in two cases with liver cirrhosis. However, the combination of circulating telomerase with serum alpha-fetoprotein level could increase the positive rate and the accuracy （92.6%, 125 of 135） of HCC diagnosis. CONCLUSION： The overexpression of telomerase is associated with HCC development, and its a
基金The National Natural Science Foundation of China under contract Nos 31272653 and 41706157the Natural Science Foundation of Fujian Province under contract No.2017J01449
文摘The chromosomes of spinyhead croaker Collichthys lucidus（Richardson,1844） were characterized for the first time by fluorescence staining,self genomic in situ hybridization（self-GISH）,and multicolor fluorescence in situ hybridization（FISH） with 18 SrDNA,5 SrDNA and telomeric sequence probes.The female karyotype has exclusively 24 pairs of acrocentric chromosomes（2 n=48 a,NF=48）,while the male one consists of 22 pairs of acrocentric chromosomes,2 monosomic acrocentric chromosomes and a metacentric chromosome（2 n=1 m＋46 a,NF=48）.The difference between female and male karyotypes indicates the presence of a sex chromosome of X1 X1 X2 X2/X1 X2 Y type,where Y is the unique metacentric chromosome in the male karyotype.As revealed by FISH,5 S r DNA and 18 S r DNA sites were mapped at syntenic position of the largest acrocentric chromosome（X_1）,and the short arms of the Y chromosome as well.An X_1-chromosome specific interstitial telomeric signal（ITS） was detected overlapping the 5 S r DNA sites.In addition,self-GISH revealed that the repetitive DNAs accumulated on all the putative sex chromosome.Chromosome fusion accompanied by a partial deletion in the ancestral karyotype（2 n=48 a） is hypothesized for the origin of such multiple sex chromosome system.The present study,as the first description of differentiated sex chromosome in family Sciaenidae,will give clues to the studies on the sex chromosome of other Sciaenids.
基金National Natural Science Foundation(Grant Nos.82271598,81871109,82071587,31930058,32330023 and 32170757)National Key Research and Development Program of China(2018YFA0107003)Guang Dong Basic and Applied Basic Research Foundation(2020A1515010462).
文摘Telomeres are specialized structures at the ends of linear chromosomes that protect genome stability.The telomeric repeat-containing RNA(TERRA)that is transcribed from subtelomeric regions can invade into double-stranded DNA regions and form RNA:DNA hybrid-containing structure called R-loop.In tumor cells,R-loop formation is closely linked to gene expression and the alternative lengthening of telomeres(ALT)pathway.Dysregulated R-loops can cause stalled replication forks and telomere instability.However,how R-loops are recognized and regulated,particularly at telomeres,is not well understood.We discovered that ILF3 selectively associates with telomeric R-loops and safeguards telomeres from abnormal homologous recombination.Knocking out ILF3 results in excessive R-loops at telomeres and triggers telomeric DNA damage responses.In addition,ILF3 deficiency disrupts telomere homeostasis and causes abnormalities in the ALT pathway.Using the proximity-dependent biotin identification(BioID)technology,we mapped the ILF3 interactome and discovered that ILF3 could interact with several DNA/RNA helicases,including DHX9.Importantly,ILF3 may aid in the resolution of telomeric R-loops through its interaction with DHX9.Our findings suggest that ILF3 may function as a reader of telomeric R-loops,helping to prevent abnormal homologous recombination and maintain telomere homeostasis.
文摘AIM To investigate the role of telomeric association in the development of esophageal cancer. METHODS Using chromosome R banding technique, telomeric association of chromosome in peripheral blood lymphocytes from 16 untreated patients with esophageal squamous cell carcinoma were observed and 16 healthy adults served as controls. RESULTS The telomeric association frequencies of cell and chromosomes were significantly higher than those of controls (x 2=9.56,P<0.01), but its distribution on the chromosome showed no significant difference (x 2=1.01, P>0.05) between the two groups. CONCLUSION Chromosomal instability can be initiated by telomeric associations, and sequential chromosome analysis can aid the understanding of the tumor occurrence and progression.
文摘Objective： To study the expression level of TRF1 （telomeric repeat binding factor 1） protein in human acute leukemia and relationship between expression level of TRF1 protein and telomerase, Methods： A quantitative Western±Blot technique was developed using anti±TRF1^33±277 monoclonal antibody and GST±TRFI purity protein as a standard to further determine the expression level of TRF1 protein in total proteins extracted from clinical specimens. Results： Bone marrow tissues of 20 acute leukemia patients were studied, 11 healthy donors＇ bone marrows were taken as a control. The expression level of TRF1 protein was significantly higher （P〈0.01） in normal bone marrow （（2.2174±0.462） μg/μl） than that of acute leukemia patients （（0.7544±0.343） μg/μl）, But there was no remarkable difference between ALL and ANLL patients （（0.6184±0.285） μg/μl vs （0.8454±0.359） μg/μl, P〉0.05）. After chemotherapy, TRFI expression level of patients with complete remission elevated （（0.7724±0.307）/μg/μl vs （1.6834±0,344）μg/μl, P〈0.01 ）, but lower than that of normal （（2.2174±0.462）/μg/μl, P〈0.01）. There was no significantly difference after chemotherapy （（0.7264±0.411） μg/μl vs （0.895±0.339） μg/μl,p〉0.05）. TRF1 expression level of patients with complete remission is higher than that of patients without complete remission （（1,683±0.344）μg/μl vs （0.895±0.339）μg/μl P〈0.01）. All samples were determined for telomerase activity. It was confirmed that the activity of telomerase in normal bone marrow was lower than that of acute leukemia patients （（0.125±0.078） μg/μl vs （0.765±0.284）μg/μl, P〈0.01）. There was no significant difference of expression level ofTRF I protein between ALL and ANLL patients （（0.897±0.290） μg/μl vs （0.677±0.268） μg/μl, P〉0.05）. After chemotherapy, telomerase activity of patients with complete remission decreased （（0.393±0.125） μg/μl）, but was
基金supported by the China Agriculture Research System(CARS-14)the Henan Provincial Agriculture Research System,China(S2012-05)the Major Technology Research and Development Program of Henan Province,China(141100110600)
文摘Interspecific hybridization is an important approach to improve cultivated peanut varieties. Cytological markers such as tandem repeats will facilitate alien gene introgression in peanut. Telomeric repeats have also been frequently used in chromosome research. Most plant telomeric repeats are（TTTAGGG）n that are mainly distributed at the chromosome ends, although interstitial telomeric repeats（ITRs） are also commonly identified. In this study, the telomeric repeat was chromosomally localized in 10 Arachis species through sequential GISH（genomic in situ hybridization） and FISH（fluorescence in situ hybridization） combined with 4＇,6-diamidino-2-phenylindole（DAPI） staining. Six ITRs were identified such as in the centromeric region of chromosome Bi5 in Arachis ipa？nsis, pericentromeric regions of chromosomes As5 in A. stenosperma, Bho7 in A. hoehnei and Av5 in A. villosa, nucleolar organizer regions of chromosomes As3 in A. stenosperma and Adi3 in A. diogoi, subtelomeric regions of chromosomes Bho9 in A. hoehnei and Adu7 in A. duranensis, and telomeric region of chromosome Es7 in A. stenophylla. The distributions of the telomeric repeat, 5S r DNA, 45 S r DNA and DAPI staining pattern provided not only ways of distinguishing different chromosomes, but also karyotypes with a higher resolution that could be used in evolutionary genome research. The distribution of telomeric repeats, 5S r DNA and 45 S r DNA sites in this study, along with inversions detected on the long arms of chromosomes Kb10 and Bho10, indicated frequent chromosomal rearrangements during evolution of Arachis species.
文摘Telomeres, which are found at the ends of eukaryotic chromosomes, are composed of tandem arrays of repetitive sequences and safeguard genomic stability. Previous studies have revealed that telomeric repeats are also present at internal chromosomal loci in many eukaryotes. However, the biological role of these interstitial telomeric sequences (ITSs) remains unknown. The integrity of telomeric length and chromatin structure is required for telomere stability. However, the study of these telomeric features can be impeded by the presence of ITSs. Frequently cutting restriction enzymes have been revealed to be very useful tools for the study of the length and chromatin structure of telomeres independent of the presence of ITSs.
基金funded by the Changchun Science and Technology Program (08KZ39)
文摘[ Objective] To observe the expression of telomerase in antler of sika deer during growth stage and thus to provide a new line for revealing the mechanisms of development and regeneration of antlers. [Method] The updated TRAP （Telomedc repeat amplification protocol） argentumdying method was used to detect the activity of telomerase in mesenchyme, precartilage, cartilage and ossification tissue of antler tip during the growth stage. Reverse transcription polymerase chain reaction （RT-PCR） was used to detect the expression of telomerase reverse transcriptase （TERT） in these cells. I-Result] The activity of telomerase was detected in the mesanchyme, precartilage and cartilage but not in the sclerotic tissue. The relative telomerase activity in the mesanchyme, precartilage and cartilage was 91.2, 46.4 and 13.7, respectively. In addition, the results of the expression of TERT gene also supported the detection result of telomerase activity. I-Conclmionl During growth phase, telomerase is expressed in multiplication area of deer antlers, and its activity decreases gradually with further differentiation of cells in antlers. Therefore, telomerase may play a key role in develoomant and rsoaneration of antlers.
文摘BAC2, a rice BAC clone containing (TTTAGGG)n homologous sequences, was analyzed by Southern hybridization and DNA sequencing of its subclones. It was disclosed that there were many tandem repeated satellite DNA sequences, called TA352, as well as simple tandem repeats consisting of TTTAGGG or its variant within the BAC2 insert. A 0. 8 kb (TTTAGGG) n-containing fragment in BAC2 was mapped in the telomere regions of at least 5 pairs of rice chromosomes by using fluorescence in situ hybridization (FISH). By RFLP analysis of low copy sequences the BAC2 clone was localized in one terminal region of chromosome 6. All the results strongly suggest that the telomeric DNA sequences of rice are TTTAGGG or its variant, and the linked satellite DNA TA352 sequences belong to telomere-associated sequences.
文摘Objective: To investigate the significance of telomerase activity in breast carcinoma with its respect to axillary lymph node status Methods: Telomerase activity was analyzed in 88 breast carcinomas and 16 benign breast lesions, using polymerase chain reaction (PCR) based telomeric repeat amplification protocol (TRAP) assay Results: Telomerase activity was detected in 75 (85%) of 88 breast carcinomas (including three breast carcinomas in situ which were all positive for telomerase activity), whereas in benign breast lesions analyzed only 2(12 5%) of 16 cases were positive for telomerase activity The difference between the two groups was statistically significant ( P <0 001) Besides, telomerase activity was expressed significantly higher in node positive breast carcinoma (93%) than in node negative ones (77%) ( P <0 05) Conclusion: Our results suggest that telomerase activation plays an important role during breast carcinoma development It is possible that this enzyme may serve as an early indication of breast carcinoma
基金supported by the National Basic Research Program of China(Grant Nos. 2009CB941000 and 2011CBA01002)
文摘Telomeres are composed of TTAGGG repeats and located at the ends of chromosomes. Telomeres protect chromosomes from instability in mammals, including mice and humans. Repetitive TTAGGG sequences are also found at intrachromosomal sites, where they are named as interstitial telomeric sequences （ITSs）. Aberrant ITSs are implicated in chromosomal instability and found in cancer cells. Interestingly, in pigs, vertebrate telomere sequences TTAGGG （vlTSs） are also localized at the centro- meric region of chromosome 6, in addition to the end of all chromosomes. Surprisingly, we found that botanic telomere se- quences, TTTAGGG （bITSs）, also localize with vITSs at the centromeric regions of pig chromosome 6 using telomere fluo- rescence in situ hybridization （FISH） and by comparisons between several species. Furthermore, the average lengths of vITSs are highly correlated with those of the terminal telomeres （TTS）. Also, pig ITSs show a high incidence of telomere doublets, suggesting that pig ITSs might be unstable and dynamic. Together, our results show that pig cells maintain the conserved te- lomere sequences that are found at the ITSs from of plants and other vertebrates. Further understanding of the function and regulation of pig ITSs may provide new clues for evolution and chromosomal instability.
基金National Natural Science Foundation of China(No.31670860 and 11835014)Recruitment Program for Leading Talent Team of Anhui Province(2019–16).
文摘Objective:To investigate the radiosensitivity of 6-thio-dG and its underlying molecular mechanisms in non-small cell lung cancer(NSCLC).Methods:H1299 and A549 NSCLC cells were pretreated with 6-thio-dG for one week and then exposed toγ-irradiation.Cell proliferation and survival were quantified using clonogenic assays.DNA damage was assessed using immunofluorescence forγH2AX.Telomere dysfunction-induced foci analysis was performed by the colocalization of telomere signals(FISH)andγH2AX.Telomere fusion was defined as two telomere signals merged into one at the chromosome by immuno-FISH in metaphase spreads.Proteins related to the DNA damage response were detected using Western blot analysis.Apoptosis wasanalyzed using flow cytometry and Western blot.Results:The presence of 6-thio-dG increased the radio sensitivity of H1299 and A549 cells(P<0.05),but had no effect on the normal human lung fibroblast line,MRC5.6-thio-dG pretreatment significantly reduced the clonogenic potential induced byγ-ray irradiation and aggravated genomic DNA and telomeric DNA damage(P<0.05).In addition,6-thio-dG pretreatment effectively increasedγ-ray irradiation induced telomere dysfunction(P<0.05),resulting in disruption of chromosome stability and inhibition of the ATM pathway,thereby impairing genomic DNA and telomeric DNA repair,which was closely associated with enhanced drug-mediated radiation-induced apoptosis.Conclusions:6-thio-dG increases the radiosensitivity of NSCLC by inhibiting ATM and inducing telomere dysfunction,which can potentially be used as a strategy for radiotherapy for NSCLC.
文摘Objective： Detecting the expression and mutation of human telomeric repeat binding factor （hTRF1） in 10 malignant hematopoietic cell line cells on the base of determining its genomic structure and its four pseudogenes to clarify ifhTRF1 mutation is one of the factors of the activation of telomerase. Methods： hTRFlcDNA sequences were obtained from GenBank, its genome structure and pseudogenes were forecasted by BLAST and other biology information programs and then testified by sequencing. Real-time RT-PCR was used to detect the expression of h TRFlmRNA in 10 cell line cells, including myelogenous leukemia cell lines K562, HL-60, U-937, NB4, THP-I, HEL and Dami; lymphoblastic leukemia cell lines 6T-CEM, Jurkat and Raji. Telomerase activities of cells were detected by using telomeric repeat amplification （TRAP）-ELISA protocol. PCR and sequencing were used to detect mutation of each exon ofhTRF1 in 10 cell line cells. Results： hTRF1 gene, mapped to 8q13, was divided into 10 exons and spans 38.6 kb. Four processed pseudogenes ofhTRF1 located on chromosome 13, 18, 21 and X respectively, was named as ψhTRFI-13, ψhTRFI-18, ψhTRF1-21 and ψhTRFI-X respectively. All cell line cells showed positive telomerase activity. The expression of hTRF1 was significantly lower in malignant hematopoietic cell lines cells （0.0338, 0.0108-0.0749） than in normal mononuclear cells （0.0493, 0.0369-0.128） （P=0.004）. But no significant mutation was found in all exons of hTRF1 in 10 cell line cells. Four variants were found in part ofintron 1, 2 and 8 ofhTRF1. Their infection on gene function is unknown and needs further studies. Conclusion： hTRF1 mutation is probably not one of the main factors for telomerase activation in malignant hematopoietic disease.
文摘Objective: To study the telomerase activity in human renal cell carcinoma and to evaluate the correlation with the clinicobiologic features of the neogrowth.Methods: The telomerase activity was studied by means of a modified telomeric repeat amplification protocol (TRAP) in 32 renal cell carcinoma tissues, 32 normal renal tissues and 32 paracancer tissues and its correlation with the clinicopathologic features of the tumor was evaluated.Results: Telomerase activity was strongly positive in 17, positive in 12 and negative in 3 cases of renal cell carcinoma tissues, the total positive rate being 91%. Telomerase activity was weakly positive (6%) in only 2 out of 32 samples of normal renal cortex tissues and positive in 6 paracancer tissues (19%), the difference was conspicuous (P<0.01).Conclusion: The positive rate of telomerase activity was significantly higher in renal cell carcinoma tissues and might serve as a prognostic marker for estimating the biologic characteristics of renal cell carcinoma.
文摘G-Quadruplexes(GQs),which are formed by G-rich DNA sequences in human telomeres,have become an attractive target for cancer treatment.The ligands to stabilize the conformation of human telomeric GQs in vivo are particularly important for structure-based ligand design and drug development targeting the noncanonical DNA structure.Here we report the conformational conversion of Tel26 induced by a naphthalene diimide(NDI)ligand in K^(+)buffer,even at cellular physiological temperature(37℃)and under mimetic cellular crowding conditions created by Ficoll 70.We provide an insight into the dynamic conversion from initial hybrid-2 GQ topology to final parallel GQ topology.These results are helpful for the design of ligands with GQ conformation regulation.
