Chromosomal instability and telomere lengths of each chromosomal arm measured by Q-FISH in human fibroblast strains prior to replicative senescence☆

Telomere lengths in Barrett's esophagus as a precancerous lesion

BACKGROUND

We have reported that precancerous conditions and lesions invariably have shorter telomeres and associated chromosomal instability relative to normal tissue.

METHODS

Using the Q-FISH method and our original software, Tissue Telo, we estimated telomere lengths in cardiac- and intestinal-type mucosae in 48 cases of Barrett's esophagus (short-segment (SS) n = 18; long-segment (LS) n = 30).

RESULTS

There were no significant differences in telomere length between the cardiac and intestinal types in any of the 48 cases, suggesting that the presence or absence of goblet cells in the columnar segments is unrelated to telomere-dependent chromosomal instability in Barrett's esophagus. In LS Barrett's esophagus, telomeres were shorter in cardiac-type than in intestinal-type mucosa, suggesting that the former may play a more important role than the latter as a precancerous lesion in LS. Telomeres in cardiac-type mucosa were longer in SS than in LS, supporting the possibility that cardiac-type LS may pose a higher risk as a precancerous lesion than cardiac-type SS.

CONCLUSIONS

Although it has been considered that Barrett's carcinoma arises only from intestinal-type mucosa, our present findings support previous histogenetic studies suggesting that cardiac-type mucosa is more important as a precancerous condition in Barrett's esophagus than anticipated.

Selected In Situ Hybridization Methods: Principles and Application

We are experiencing rapid progress in all types of imaging techniques used in the detection of various numbers and types of mutation. In situ hybridization (ISH) is the primary technique for the discovery of mutation agents, which are presented in a variety of cells. The ability of DNA to complementary bind is one of the main principles in every method used in ISH. From the first use of in situ techniques, scientists paid attention to the improvement of the probe design and detection, to enhance the fluorescent signal intensity and inhibition of cross-hybrid presence. This article discusses the individual types and modifications, and is focused on explaining the principles and limitations of ISH division on different types of probes. The article describes a design of probes for individual types of in situ hybridization (ISH), as well as the gradual combination of several laboratory procedures to achieve the highest possible sensitivity and to prevent undesirable events accompanying hybridization. The article also informs about applications of the methodology, in practice and in research, to detect cell to cell communication and principles of gene silencing, process of oncogenesis, and many other unknown processes taking place in organisms at the DNA/RNA level.

Qualitative and quantitative alterations in intracellular and membrane glycoproteins maintain the balance between cellular senescence and human aging

Glycans are associated with and serve as biomarkers for various biological functions. We previously reported that cell surface sialylated glycoproteins of dermal fibroblasts decreased with cellular senescence and human aging. There is little information on the changes in glycoprotein expression and subcellular localization during the aging process. Here, we examined intracellular glycan profiles of fibroblasts undergoing cellular senescence and those derived from aging human subjects using lectin microarray analysis. We found a sequential change of the intracellular glycan profiles was little during cellular senescence. The intracellular glycans of cells derived from aged fetus and from elderly subjects showed similar localized patterns while repeating unsteady changes. The ratio of α2-3/2-6sialylated intracellular glycoproteins in total cell extracts increased, except for a part of α2-3sialylated O-glycans. These findings are in contrast to those for membrane glycoprotein, which decreased with aging. Interestingly, the ratio of increasing sialylated glycoproteins in the fetus-derived cells showing cellular senescence was similar to that in cells derived from the elderly. Thus, intracellular glycans may maintain cellular functions such as ubiquitin/proteasome-mediated degradation and/or autophagy during aging by contributing to the accumulation of intracellular glycosylated proteins. Our findings provide novel mechanistic insight into the molecular changes that occur during aging.

Telomere shortening by transgenerational transmission of TNF-α-induced TERRA via ATF7

Various stresses increase disease susceptibility and accelerate aging, and increasing evidence suggests that these effects can be transmitted over generation. Epidemiological studies suggest that stressors experienced by parents affect the longevity of their offspring, possibly by regulating telomere dynamics. Telomeres are elongated by telomerase and shortened by certain stresses as well as telomere repeat-containing RNA (TERRA), a telomere transcript. However, the mechanism underlying the transgenerational effects is poorly understood. Here, we show that TNF-α, which is induced by various psychological stresses, induces the p38-dependent phosphorylation of ATF7, a stress-responsive chromatin regulator, in mouse testicular germ cells. This caused a release of ATF7 from the TERRA gene promoter in the subtelomeric region, which disrupted heterochromatin and induced TERRA. TERRA was transgenerationally transmitted to zygotes via sperm and caused telomere shortening. These results suggest that ATF7 and TERRA play key roles in paternal stress-induced telomere shortening in the offspring.

ATF7 mediates TNF-α-induced telomere shortening

Telomeres maintain the integrity of chromosome ends and telomere length is an important marker of aging. The epidemiological studies suggested that many types of stress including psychosocial stress decrease telomere length. However, it remains unknown how various stresses induce telomere shortening. Here, we report that the stress-responsive transcription factor ATF7 mediates TNF-α–induced telomere shortening. ATF7 and telomerase, an enzyme that elongates telomeres, are localized on telomeres via interactions with the Ku complex. In response to TNF-α, which is induced by various stresses including psychological stress, ATF7 was phosphorylated by p38, leading to the release of ATF7 and telomerase from telomeres. Thus, a decrease of ATF7 and telomerase on telomeres in response to stress causes telomere shortening, as observed in ATF7-deficient mice. These findings give credence to the idea that various types of stress might shorten telomere.

Ontogenetic and Pathogenetic Views on Somatic Chromosomal Mosaicism

Intercellular karyotypic variability has been a focus of genetic research for more than 50 years. It has been repeatedly shown that chromosome heterogeneity manifesting as chromosomal mosaicism is associated with a variety of human diseases. Due to the ability of changing dynamically throughout the ontogeny, chromosomal mosaicism may mediate genome/chromosome instability and intercellular diversity in health and disease in a bottleneck fashion. However, the ubiquity of negligibly small populations of cells with abnormal karyotypes results in difficulties of the interpretation and detection, which may be nonetheless solved by post-genomic cytogenomic technologies. In the post-genomic era, it has become possible to uncover molecular and cellular pathways to genome/chromosome instability (chromosomal mosaicism or heterogeneity) using advanced whole-genome scanning technologies and bioinformatic tools. Furthermore, the opportunities to determine the effect of chromosomal abnormalities on the cellular phenotype seem to be useful for uncovering the intrinsic consequences of chromosomal mosaicism. Accordingly, a post-genomic review of chromosomal mosaicism in the ontogenetic and pathogenetic contexts appears to be required. Here, we review chromosomal mosaicism in its widest sense and discuss further directions of cyto(post)genomic research dedicated to chromosomal heterogeneity.

Changes in telomere length with aging in human neurons and glial cells revealed by quantitative fluorescence in situ hybridization analysis

AIM

The telomere is a structure present at the ends of chromosomes, and is known to shorten with aging and successive rounds of cell division. However, very little is known about telomere attrition in post-mitotic cells, such as neurons.

METHODS

Using our originally developed quantitative fluorescence in situ hybridization method, we analyzed age-dependent alterations of telomere length in three types of cells in the human cerebrum: neurons and glial cells in both the gray and white matter.

RESULTS

In adults, telomeres were significantly longer in neurons than in glial cells, whereas in infants, telomere lengths did not differ among the three cell types. No aging-related telomere attrition was evident in neurons. However, the telomeres of glial cells were shorter in older individuals than in younger individuals, and attrition was more rapid in the white matter than in the gray matter.

CONCLUSIONS

The present results suggest that the telomeres of neurons remain stable throughout life, whereas telomeres in white matter glial cells become significantly shorter with age. Examination of adults showed no significant correlation between telomere length and age in the three cell types. Although the present study was cross-sectional, the results suggest that telomere shortening before adolescence contributes to the significant decrease of telomere length in white matter glial cells. The present findings in normal cerebral tissues will be informative for future studies of telomere stability in the diseased brain. Geriatr Gerontol Int 2018; 18: 1507-1512.

Telomere length of gallbladder epithelium is shortened in patients with congenital biliary dilatation: measurement by quantitative fluorescence in situ hybridization

BACKGROUND

Congenital biliary dilatation (CBD) is a congenital malformation involving both dilatation of the extrahepatic bile duct and pancreaticobiliary maljunction. Persistent reflux of pancreatic juice injures the biliary tract mucosa, resulting in chronic inflammation and higher rates of carcinogenesis in the biliary tract, including the gallbladder. Telomeres are repetitive DNA sequences located at the ends of chromosomes. Chromosomal instability due to telomere dysfunction plays an important role in the carcinogenesis of many organs. This study was performed to determine whether excessive shortening of telomeres occurs in the gallbladder mucosa of patients with CBD.

METHODS

Resected gallbladders were obtained from 17 patients with CBD, ten patients with cholecystolithiasis without pancreatic juice reflux, and 17 patients with normal gallbladders (controls) (median age of each group of patients: 37, 50, and 53 years, respectively). The telomere lengths of the gallbladder epithelium were measured by quantitative fluorescence in situ hybridization using tissue sections, and the normalized telomere-to-centromere ratio (NTCR) was calculated.

RESULTS

The NTCRs in the CBD, cholecystolithiasis, and control groups were 1.24 [interquartile range (IQR) 1.125-1.52], 1.96 (IQR 1.56-2.295), and 1.77 (IQR 1.48-2.53), respectively. The NTCR in the CBD group was significantly smaller than that in the cholecystolithiasis and control groups (p = 0.003 and 0.004, respectively), even in young patients.

CONCLUSIONS

Our findings indicate that telomere shortening in the gallbladder mucosa plays an important role in the process of carcinogenesis in patients with CBD. These results support the recommendation of established guidelines for prophylactic surgery in patients with CBD because CBD is a premalignant condition with excessive telomere shortening.

Changes of telomere status with aging: An update

Accumulated data have shown that most human somatic cells or tissues show irreversible telomere shortening with age, and that there are strong associations between telomere attrition and aging-related diseases, including cancers, diabetes and cognitive disorders. Although it has been largely accepted that telomere attrition is one of the major causes of aging-related disorders, critical aspects of telomere biology remain unresolved, especially the lack of standardized methodology for quantification of telomere length. Another frustrating issue is that no potentially promising methods for safe prevention of telomere erosion, or for telomere elongation, have been devised. Here, we review several methods for quantification of telomere length currently utilized worldwide, considering their advantages and drawbacks. We also summarize the results of our recent studies of human cells and tissues, mainly using quantitative fluorescence in situ hybridization and Southern blotting, including those derived from patients with progeria-prone Werner syndrome and trisomy 21, and several strains of induced pluripotent stem cells. We discuss the possible merits of using telomere shortness as an indicator, or a new marker, for diagnosis of precancerous states and aging-related disorders. In addition, we describe newly found factors that are thought to impact telomere dynamics, providing a new avenue for examining the unsolved issues related to telomere restoration and maintenance.

N- and O-glycan cell surface protein modifications associated with cellular senescence and human aging

Background

Glycans play essential roles in biological functions such as differentiation and cancer. Recently, glycans have been considered as biomarkers for physiological aging. However, details regarding the specific glycans involved are limited. Here, we investigated cellular senescence- and human aging-dependent glycan changes in human diploid fibroblasts derived from differently aged skin donors using a lectin microarray.

Results

We found that α2-6sialylated glycans in particular differed between elderly- and fetus-derived cells at early passage. However, both cell types exhibited sequentially decreasing α2-3sialylated O-glycan structures during the cellular senescence process and showed similar overall glycan profiles.

Conclusions

We observed a senescence-associated decrease in sialylation and increase in galactose exposure. Therefore, glycan profiling using lectin microarrays might be useful for the characterization of biomarkers of aging.

Electronic supplementary material

The online version of this article (doi:10.1186/s13578-016-0079-5) contains supplementary material, which is available to authorized users.

β-cell telomere attrition in diabetes: inverse correlation between HbA1c and telomere length

CONTEXT

Although accelerated β-cell telomere shortening may be associated with diabetes that shows a dramatically increased incidence with aging, β-cell telomere length in diabetes has never been explored.

OBJECTIVE

The objective of the present study was to examine telomere length in the β-cells of patients with diabetes.

DESIGN AND PATIENTS

We determined telomere length in β- and α-cells of pancreases obtained at autopsy from 47 patients with type 2 diabetes and 51 controls, all older than 60 years.

MAIN OUTCOME MEASURE

The normalized telomere to centromere ratio (NTCR), an index of telomere length, was determined for β- (NTCRβ) and α- (NTCRα) cells by quantitative fluorescence in situ hybridization.

RESULTS

The NTCRβ was reduced by 27% ± 25% and NTCRα by 15% ± 27% in the patients with diabetes relative to the controls (P < .01 for both). Importantly, the degree of shortening was significantly (P < .01) greater in β-cells than in α-cells. The histogram of NTCR distribution was significantly skewed to the left in the patients with diabetes relative to the controls for both β- and α-cells, indicating preferential depletion of longer-telomere islet cells. Glycated hemoglobin was negatively correlated with β-cell telomere length, and the telomeres were significantly shorter in patients who had used hypoglycemic agents than in those who had not.

CONCLUSION

The telomeres of β-cells are shortened in patients with type 2 diabetes. There may be a vicious cycle involving β-cell telomere attrition and sustained hyperglycemia.

Ataxia telangiectasia derived iPS cells show preserved x-ray sensitivity and decreased chromosomal instability

Ataxia telangiectasia is a neurodegenerative inherited disease with chromosomal instability and hypersensitivity to ionizing radiation. iPS cells lacking ATM (AT-iPS cells) exhibited hypersensitivity to X-ray irradiation, one of the characteristics of the disease. While parental ataxia telangiectasia cells exhibited significant chromosomal abnormalities, AT-iPS cells did not show any chromosomal instability in vitro for at least 80 passages (560 days). Whole exome analysis also showed a comparable nucleotide substitution rate in AT-iPS cells. Taken together, these data show that ATM is involved in protection from irradiation-induced cell death.

Q-FISH measurement of hepatocyte telomere lengths in donor liver and graft after pediatric living-donor liver transplantation: donor age affects telomere length sustainability

Along with the increasing need for living-donor liver transplantation (LDLT), the issue of organ shortage has become a serious problem. Therefore, the use of organs from elderly donors has been increasing. While the short-term results of LDLT have greatly improved, problems affecting the long-term outcome of transplant patients remain unsolved. Furthermore, since contradictory data have been reported with regard to the relationship between donor age and LT/LDLT outcome, the question of whether the use of elderly donors influences the long-term outcome of a graft after LT/LDLT remains unsettled. To address whether hepatocyte telomere length reflects the outcome of LDLT, we analyzed the telomere lengths of hepatocytes in informative biopsy samples from 12 paired donors and recipients (grafts) of pediatric LDLT more than 5 years after adult-to-child LDLT because of primary biliary atresia, using quantitative fluorescence in situ hybridization (Q-FISH). The telomere lengths in the paired samples showed a robust relationship between the donor and grafted hepatocytes (r = 0.765, p = 0.0038), demonstrating the feasibility of our Q-FISH method for cell-specific evaluation. While 8 pairs showed no significant difference between the telomere lengths for the donor and the recipient, the other 4 pairs showed significantly shorter telomeres in the recipient than in the donor. Multiple regression analysis revealed that the donors in the latter group were older than those in the former (p = 0.001). Despite the small number of subjects, this pilot study indicates that donor age is a crucial factor affecting telomere length sustainability in hepatocytes after pediatric LDLT, and that the telomeres in grafted livers may be elongated somewhat longer when the grafts are immunologically well controlled.

Quantitative fluorescence in situ hybridization measurement of telomere length in skin with/without sun exposure or actinic keratosis

Chromosomal and genomic instability due to telomere dysfunction is known to play an important role in carcinogenesis. To study telomere shortening in the epidermis surrounding actinic keratosis, we measured telomere lengths of basal, parabasal, and suprabasal cells in epidermis with actinic keratosis (actinic keratosis group, n = 18) and without actinic keratosis (sun-protected, n = 15, and sun-exposed, n = 13 groups) and in actinic keratosis itself as well as in dermal fibroblasts in the 3 groups, using quantitative fluorescence in situ hybridization. Among the 3 cell types, telomeres of basal cells were not always the longest, suggesting that tissue stem cells are not necessarily located among basal cells. Telomeres of basal cells in the sun-exposed group were shorter than those in the sun-protected group. Telomeres in the background of actinic keratosis and in actinic keratosis itself and those of fibroblasts in actinic keratosis were significantly shorter than those in the controls. Our findings demonstrate that sun exposure induces telomere shortening and that actinic keratosis arises from epidermis with shorter telomeres despite the absence of any histologic atypia.

Investigation of telomere length dynamics in induced pluripotent stem cells using quantitative fluorescence in situ hybridization

Here we attempted to clarify telomere metabolism in parental cells and their derived clonal human induced pluripotent stem cells (iPSCs) at different passages using quantitative fluorescence in situ hybridization (Q-FISH). Our methodology involved estimation of the individual telomere lengths of chromosomal arms in individual cells within each clone in relation to telomere fluorescence units (TFUs) determined by Q-FISH. TFUs were very variable within the same metaphase spread and within the same cell. TFUs of the established iPSCs derived from human amnion (hAM933 iPSCs), expressed as mean values of the median TFUs of 20 karyotypes, were significantly longer than those of the parental cells, although the telomere extension rates varied quite significantly among the clones. Twenty metaphase spreads from hAM933 iPSCs demonstrated no chromosomal instability. The iPSCs established from fetal lung fibroblasts (MRC-5) did not exhibit telomere shortening and chromosomal instability as the number of passages increased. However, the telomeres of other iPSCs derived from MRC-5 became shorter as the number of passages increased, and one (5%) of 20 metaphase spreads showed chromosomal abnormalities including X trisomy at an early stage and all 20 showed abnormalities including X and 12 trisomies at the late stage.

Human Xp/Yp telomere analysis by Southern-STELA

Telomeres are specialized structures designed to protect the ends of linear chromosomes. They are dynamic structures such that in normal somatic cells they constantly shorten as cell division progresses. There is compelling evidence that telomere shortening leads to cell senescence, a process perceived as the main cause of aging in higher mammals. Therefore, the features of telomere shortening are of great importance in understanding cell senescence and aging in general. By identifying unique subtelomeric regions, large enough to produce strong chemiluminescent signals, we have provided a new tool for Southern blot analysis of individual human Xp/Yp telomeres. We extend these results with quantitative fluorescence in situ hybridization using peptide nucleic acid probe (PNA Q-FISH) analysis of telomeres on the Y chromosome. Our results demonstrates unequal shortening dynamics between the p and q telomeres.

Evaluation of senescence in mesenchymal stem cells isolated from equine bone marrow, adipose tissue, and umbilical cord tissue

Mesenchymal stem cells (MSCs) from adult and neonatal tissues are intensively investigated for their use in regenerative medicine. The purpose of this study was to compare the onset of replicative senescence in MSCs isolated from equine bone marrow (BMSC), adipose tissue (ASC), and umbilical cord tissue (UCMSC). MSC proliferation (cell doubling), senescence-associated β-galactosidase staining, telomere length, Sox-2, and lineage-specific marker expression were assessed for MSCs harvested from tissues of 4 different donors. The results show that before senescence ensued, all cell types proliferated at ∼1 day/cell doubling. BMSCs significantly increased population doubling rate by passage 10 and ceased proliferation after a little >30 total population doublings, whereas UCMSCs and ASCs achieved about 60 to 80 total population doublings. UCMSC and ASCs showed marked β-galactosidase staining after ∼70 population doublings, whereas BMSCs stained positive by ∼30 population doublings. The onset of senescence was associated with a significant reduction in telomere length averaging 10.2 kbp at passage 3 and 4.5 kbp in senescent cultures. MSCs stained intensively for osteonectin at senescence compared with earlier passages, whereas vimentin and low levels of smooth muscle actin were consistently expressed. Sox-2 gene expression was consistently noted in all 3 MSC types. In conclusion, equine BMSCs appear to senesce much earlier than ASCs and UCMSCs. These results demonstrate the limited passage numbers of subcultured BMSCs available for use in research and tissue engineering and suggest that adipose tissue and umbilical cord tissue may be preferable for tissue banking purposes.