Humans ; Telomere ; metabolism ; Telomere-Binding Proteins ; metabolism

Humans ; Metabolic Syndrome ; Telomerase ; metabolism ; Telomere

Pluripotent stem cells (PSCs) have the potential to produce any types of cells from all three basic germ layers and the capacity to self-renew and proliferate indefinitely in vitro. The two main types of PSCs, embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), share common features such as colony morphology, high expression of Oct4 and Nanog, and strong alkaline phosphatase activity. In recent years, increasing evidences suggest that telomere length represents another important internal factor in maintaining stem cell pluripotency. Telomere length homeostasis and its structural integrity help to protect chromosome ends from recombination, end fusion, and DNA damage responses, ensuring the divisional ability of mammalian cells. PSCs generally exhibit high telomerase activity to maintain their extremely long and stable telomeres, and emerging data indicate the alternative lengthening of telomeres (ALT) pathway may play an important role in telomere functions too. Such characteristics are likely key to their abilities to differentiate into diverse cell types in vivo. In this review, we will focus on the function and regulation of telomeres in ESCs and iPSCs, thereby shedding light on the importance of telomere length to pluripotency and the mechanisms that regulate telomeres in PSCs.
Animals ; Humans ; Models, Biological ; Pluripotent Stem Cells ; metabolism ; Telomerase ; metabolism ; Telomere ; metabolism ; Telomere Homeostasis

PURPOSE: An attempt was made to investigate N-nitrosomorpholine (NNM) induced carcinogenic processes in rat liver. MATERIALS AND METHODS: Rats were fed with NNM (200 mg/l) for 7 weeks, after then stopped. Length of telomere and activity of telomerase were analyzed. Hepatocytes were isolated and grown on tissue culture. Heat shock was treated at 43oC, and patterns of cell death ere evaluted by fluorescent study. Nuclei and nucleoli were isolated for analysis of various signal molecules. RESULTS: Shortening of telomere length presented in NNM treated liver, but induction of telomerase was not found. Ex vivo hepatocytes from 10~12th week showed increased heat shock resistance at 43oC. NNM-treated hepatocytes exhibited heat shock induced cell death (necrosis) after 7 hours, whereas the control showed necrosis after 3 hours. The signal molecules related to nucleolar growth revealed increased expression which included B23, C23, p38, Erk1/2 and p120. Partial degradation of B23 and Erk2 was noted in necrosis of NNM treated hepatocytes induced by heat shock. CONCLUSION: The hepatocytes at the stage of 10~12th week in the stop experiment of NNM are situated in the tumour promotion. Those cells showed various metabolic alterations. We found that the increased growth related signals were accompanied with increased heat shock resistance, telomere shortening but no induction of telomerase.
Animals ; Cell Death ; Hepatocytes* ; Hot Temperature ; Liver ; Metabolism* ; Necrosis ; Rats* ; Shock ; Telomerase ; Telomere ; Telomere Shortening

Telomerase reverse transcriptase (TERT) is the protein component of telomerase and combined with an RNA molecule, telomerase RNA component, forms the telomerase enzyme responsible for telomere elongation. Telomerase is essential for maintaining telomere length from replicative attrition and thus contributes to the preservation of genome integrity. Although diverse mouse models have been developed and studied to prove the physiological roles of telomerase as a telomere-elongating enzyme, recent studies have revealed non-canonical TERT activities beyond telomeres. To gain insights into the physiological impact of extra-telomeric roles, this review revisits the strategies and phenotypes of telomerase mouse models in terms of the extra-telomeric functions of telomerase.
Animals ; Mice ; Mice, Knockout ; Telomerase/genetics/*metabolism ; Telomere/metabolism

Lamin B1 (LMNB1) is highly expressed in liver cancer tissues, and its influence and mechanism on the proliferation of hepatocellular carcinoma cells were explored by knocking down the expression of the protein. In liver cancer cells, siRNAs were used to knock down LMNB1. Knockdown effects were detected by Western blotting. Changes in telomerase activity were detected by telomeric repeat amplification protocol assay (TRAP) experiments. Telomere length changes were detected by quantitative real-time polymerase chain reaction (qPCR). CCK8, cloning formation, transwell and wound healing were performed to detect changes in its growth, invasion and migration capabilities. The lentiviral system was used to construct HepG2 cells that steadily knocked down LMNB1. Then the changes of telomere length and telomerase activity were detected, and the cell aging status was detected by SA-β-gal senescence staining. The effects of tumorigenesis were detected by nude mouse subcutaneous tumorigenesis experiments, subsequent histification staining of tumors, SA-β-gal senescence staining, fluorescence in situ hybridization (FISH) for telomere analysis and other experiments. Finally, the method of biogenesis analysis was used to find the expression of LMNB1 in clinical liver cancer tissues, and its relationship with clinical stages and patient survival. Knockdown of LMNB1 in HepG2 and Hep3B cells significantly reduced telomerase activity, cell proliferation, migration and invasion abilities. Experiments in cells and tumor formation in nude mice had demonstrated that stable knockdown of LMNB1 reduced telomerase activity, shortened telomere length, senesced cells, reduced cell tumorigenicity and KI-67 expression. Bioinformatics analysis showed that LMNB1 was highly expressed in liver cancer tissues and correlated with tumor stage and patient survival. In conclusion, LMNB1 is overexpressed in liver cancer cells, and it is expected to become an indicator for evaluating the clinical prognosis of liver cancer patients and a target for precise treatment.
Animals ; Mice ; Telomerase/metabolism* ; Carcinoma, Hepatocellular/genetics* ; Liver Neoplasms/genetics* ; Telomere Shortening ; In Situ Hybridization, Fluorescence ; Mice, Nude ; Telomere/pathology* ; Carcinogenesis

AIMTo simultaneously determine the localization of histones and protamines within human sperm nuclei.

METHODSImmunofluorescence of the core histones and protamines and fluorescence in situ hybridization of the telomere region of chromosome 16 was assessed in decondensed human sperm nuclei.

RESULTSImmunofluorescent localization of histones, protamine 1 (PRM1) and protamine 2 (PRM2) along with fluorescence in situ hybridization localization of chromosome 16 telomeric sequences revealed a discrete distribution in sperm nuclei. Histones localized to the posterior ring region (i.e. the sperm nuclear annulus), whereas PRM1 and PRM2 appeared to be dispersed throughout the entire nucleus.

CONCLUSIONThe co-localization of the human core sperm histones with the telomeric regions of chromosome 16 is consistent with the reorganization of specific non-protamine regions into a less compacted state.

Cell Nucleus ; metabolism ; Chromosomes, Human, Pair 16 ; metabolism ; Histones ; metabolism ; Humans ; Male ; Protamines ; metabolism ; Spermatozoa ; metabolism ; Telomere ; metabolism

OBJECTIVETo measure telomere length of patients with bone marrow failure syndrome (BMFS) and explore the relationship between telomerase gene mutation and telomere shortening.

METHODSBlood samples from 10 patients with AA, MDS-RA were collected and performed TERC and TERT gene mutation analysis. Telomere length was measured by Southern blot and compared with normal controls and two patients with MDS-RAEB and AML each.

RESULTSTwo patients in the 10 BMFS patients had TERC and TERT gene mutations and very short telomeres compared with normal controls and with the 8 BMFS counterparts, the telomere length was less than 50% of that of normal control, and was similar to that of patients with MDS-RAEB and acute myelogenous leukemia, indicating the possibility of malignant transformation. Some BMFS patients with no mutations also had short telomeres.

CONCLUSIONSBMFS patients with telomerase gene mutation have very short telomeres, being similar to that of hematological malignancies. Some BMFS patients with no telomerase gene mutations also have short telomere length.

Asian Continental Ancestry Group ; Humans ; Mutation ; Pancytopenia ; Telomerase ; metabolism ; Telomere ; metabolism

OBJECTIVETo investigate the proportion between tumors which maintain their telomeres by a mechanism of alternative lengthening of telomeres(ALT) and telomerase-dependent tumors in gastrointestinal malignant tumors, the expression difference of hRad21 between the two groups and the clinicopathological characteristics of ALT tumors were also explored.

METHODSOne hundred and four cases of gastrointestinal malignant tumors were divided into 2 groups: ALT group and telomerase group by detecting telomerase activity using TRAP method. Expression difference of hRad21 was investigated between the two groups. All the patients were followed up and clinicopathological data of these patients were analyzed.

RESULTSOf 104 cases, there were 12 cases in ALT group and 94 cases in telomerase group. Expression of hRad21 in ALT group was higher than that in telomerase group. Tumors in ALT group had a thinner invasion depth (lower T stage) as compared to telomerase group (P=0.021). Other indexes, such as age, gender, tumor size, tumor grade, location of tumor, CEA and CA199, were not significantly different between the two groups. Results of follow-up showed that the survival rate of ALT group was 100% while that of telomerase group was 56% at 30 months postoperatively.

CONCLUSIONSThere are tumors which maintain their telomeres by ALT in gastrointestinal malignant tumors, accounting for 10%-12% of the total tumors. As compared to telomerase group, ALT group presents higher expression of hRad21, thinner tumor invasion depth, and higher survival rate.

Female ; Gastrointestinal Neoplasms ; metabolism ; pathology ; Humans ; Male ; Neoplasm Invasiveness ; Nuclear Proteins ; metabolism ; Phosphoproteins ; metabolism ; Telomerase ; metabolism ; Telomere ; metabolism

With the smooth move towards the coming expected clinical reports of anticancer pharmaceutical molecules targeting telomeres and telomerase, and also with the exciting success in the extension of lifespan by regulating telomerase activity without increased onset of oncogenesis in laboratory mouse models (Garcia-Cao et al., 2006; Jaskelioff et al., 2011), we are convinced that targeting telomeres based on telomerase will be a potential approach to conquer both aging and cancer and the idea of longevity seems to be no more mysterious. More interestingly, emerging evidences from clinical research reveal that other telomeric factors, like specific telomeric binding proteins and nonspecific telomere associated proteins also show crucial importance in aging and oncogenesis. This stems from their roles in the stability of telomere structure and in the inhibition of DNA damage response at telomeres. Uncapping these proteins from chromosome ends leads to dramatic telomere loss and telomere dysfunction which is more abrupt than those induced by telomerase inactivation. Abnormal expression of these factors results in developmental failure, aging and even oncogenesis evidenced by several experimental models and clinical cases, indicating telomere specific proteins and its associated proteins have complimentary roles to telomerase in telomere protection and controlling cellular fate. Thus, these telomeric factors might be potential clinical biomarkers for early detection or even therapeutic targets of aging and cancer. Future studies to elucidate how these proteins function in telomere protection might benefit patients suffering aging or cancer who are not sensitive to telomerase mediation.
Aging ; Biomarkers ; metabolism ; Humans ; Longevity ; Neoplasms ; metabolism ; pathology ; Telomerase ; metabolism ; Telomere ; metabolism ; ultrastructure ; Telomeric Repeat Binding Protein 2 ; metabolism