Influence of donor liver telomere and G-tail on clinical outcome after living donor liver transplantation.

It has been reported that donor age affects patient outcomes after liver transplantation, and that telomere length is associated with age. However, to our knowledge, the impact of donor age and donor liver telomere length in liver transplantation has not been well investigated. This study aimed to clarify the influence of the length of telomere and G-tail from donor livers on the outcomes of living donors and recipients after living donor liver transplantation. The length of telomere and G-tail derived from blood samples and liver tissues of 55 living donors, measured using the hybridization protection assay. The length of telomeres from blood samples was inversely correlated with ages, whereas G-tail length from blood samples and telomere and G-tail lengths from liver tissues were not correlated with ages. Age, telomere, and G-tail length from blood did not affect postoperative liver failure and early liver regeneration of donors. On the other hand, the longer the liver telomere, the poorer the liver regeneration tended to be, especially with significant difference in donor who underwent right hemihepatectomy. We found that the survival rate of recipients who received liver graft with longer telomeres was inferior to that of those who received liver graft with shorter ones. An elderly donor, longer liver telomere, and higher Model for End-Stage Liver Disease score were identified as independent risk factors for recipient survival after transplantation. In conclusion, telomere shortening in healthy liver does not correlate with age, whereas longer liver telomeres negatively influence donor liver regeneration and recipient survival after living donor liver transplantation. These results can direct future studies and investigations on telomere shortening in the clinical and experimental transplant setting.

Telomere G-tail Length is a Promising Biomarker Related to White Matter Lesions and Endothelial Dysfunction in Patients With Cardiovascular Risk: A Cross-sectional Study.

BACKGROUND: The telomeric 3'-overhang (G-tail) length is essential for the biological effects of telomere dysfunction in vitro, but the association of length with aging and cardiovascular risk is unclear in humans. We investigated the association between the telomere G-tail length of leukocytes and cardiovascular risk, age-related white matter changes (ARWMCs), and endothelial function. METHODS: Patients with a history of cerebrovascular disease and comorbidity were enrolled (n = 102; 69 males and 33 females, 70.1 ± 9.2 years). Total telomere and telomere G-tail lengths were measured using a hybridization protection assay. Endothelial function was evaluated by ultrasound assessment of brachial flow-mediated dilation (FMD). FINDINGS: Shortened telomere G-tail length was associated with age and Framingham risk score (P = 0.018 and P = 0.012). In addition, telomere G-tail length was positively correlated with FMD values (P = 0.031) and negatively with the severity of ARWMCs (P = 0.002). On multivariate regression analysis, telomere G-tail length was independently associated with FMD values (P = 0.022) and the severity of ARWMCs (P = 0.033), whereas total telomere length was not associated with these indicators. INTERPRETATION: Telomere G-tail length is associated with age and vascular risk factors, and might be superior to total telomere length as a marker of endothelial dysfunction and ARWMC severity.

Telomeric g-tail length and hospitalization for cardiovascular events in hemodialysis patients.

BACKGROUND AND OBJECTIVES: Telomeric G-tails play a pivotal role in maintaining the intramolecular loop structure of telomeres. Previous in vitro studies have suggested that the erosion of telomeric G-tails triggers cellular senescence, leading to organ dysfunction and atherosclerosis. The authors recently established a method to measure telomeric G-tail length using a hybridization protection assay. Using this method, this study investigated whether telomeric G-tail length could be used as a novel predictor for future cardiovascular events in hemodialysis patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A prospective observational study was performed involving a cohort of 203 Japanese hemodialysis patients to examine the lengths of telomeric G-tails and total telomeres and subsequent cardiovascular events during a median follow-up period of 48 months. The lengths of telomeric G-tails and total telomeres were also measured in 203 participants who did not have CKD and who were age- and sex-matched to hemodialysis patients. RESULTS: The lengths of telomeric G-tails and total telomeres were significantly shorter in hemodialysis patients than in control subjects. Telomeric G-tails, but not total telomeres, were independently and negatively associated with clinical history of cardiovascular disease. During follow-up, 80 cardiovascular events occurred. Total telomere length did not predict cardiovascular events. However, the length of telomeric G-tails was associated with new-onset cardiovascular events (hazard ratio per log luminescence signals, 0.12; 95% confidence interval, 0.12 to 0.50) that persisted after adjustment for age, sex, diabetes mellitus, clinical history of cardiovascular disease, inflammation, use of vitamin D, and serum levels of phosphate and intact parathyroid hormone. CONCLUSIONS: Longer telomeric G-tail length is associated with a lower risk of future cardiovascular events in hemodialysis patients.

Establishment of functional telomerase immortalized human hepatocytes and a hepatic stellate cell line for telomere-targeting anticancer drug development.

We previously reported that the telomere-targeting drug telomestatin induces apoptosis accompanied by G-tail reduction and dissociation of binding protein TRF2 from telomeres in cancer cell lines but not normal or human telomerase reverse transcriptase (hTERT)-immortalized cells. Because telomere-targeting drugs induce growth arrest in normal cells at higher doses, their development is dependent on the ability to predict toxicity before in vivo use, but no models for this are available. Here, we established two new cell lines, telomerase immortalized human fetal hepatocytes, Hc3716-hTERT, and telomerase immortalized hepatic stellate cells, NPC-hTERT. Examinations showed that Hc3716-hTERT maintained normal mammalian cell morphology, cell growth, albumin expression, and wild-type p53 responsiveness, whereas NPC-hTERT maintained hepatic stellate-like morphology, expression of hepatic stellate markers, alpha-smooth muscle actin, and secretion of type I collagen, an extracellular matrix protein. Given our finding that telomere G-tail length in Hc3716 cells was decreased in senescence and increased by hTERT infection, we next examined the effect of high-dose telomestatin-induced telomere dysfunction and G-tail shortening on cellular functions in Hc3716-hTERT cells. Interestingly, telomestatin decreased expression of cytochrome P450 (CYP) family members CYP3A3/4, CYP3A5, and CYP3A7, mRNA and induced albumin expression at both mRNA and protein levels. These gene expression responses to telomestatin were similar to those of the normal parental cell Hc3716. These established cell lines thus represent the first model for predicting the side-effects of telomere-targeting drugs in normal cells, and should be powerful tools in the development of these drugs.

Telomerase activation induces elongation of the telomeric single-stranded overhang, but does not prevent chromosome aberrations in human vascular endothelial cells.

Chromosome aberrations such as loss of chromosome 13 were frequently observed in human endothelial cells from umbilical cord veins (HUVEC). A recent study showed that the length of telomeric single-stranded 3'-overhangs (G-tails) is more important as an essential structure for chromosome maintenance than the net telomere length in telomere t-loop formation. Here, we have examined G-tail length using G-tail telomere HPA in normal and hTERT-transduced HUVECs. We found that forced expression of hTERT in HUVEC induced G-tail as well as total telomere length elongation. G-tail length was well correlated with total telomere length. However, hTERT introduction did not prevent chromosome aberrations such as loss of chromosome 13. Normal characteristics such as morphology, up-regulation of vWF, and tube formation were observed in hTERT-HUVEC as in young normal HUVEC. These results show that chromosome aberrations in HUVEC are independent of telomere G-tail and total telomere attrition.