Telomeres are elongated in rats exposed to moderate altitude

TERT mutations-associated alterations in clinical characteristics, immune environment and therapy response in glioblastomas

OBJECTIVE TERT: is the most frequently mutated gene in adult glioblastomas (GBMs) defined by the 2021 World Health Organization classification system. The present study aims to explore differences in clinical characteristics and immune microenvironment between TERT mutant and wild-type GBM.

METHODS

Three GBM-related cohorts consisting of 205 GBM patients in our cohort, 463 GBM patients without immune checkpoint inhibitor(ICI) therapy and 1465 tumour patients (including 92 GBM cases) receiving ICI treatment in the MSK cohort were included. Retrospective analysis and immunohistochemistry assay were used for investigating the local (including tumour cells, local immune cells, and seizures) and systemic (including circulating immune cells, coagulation-related functions, and prognosis) effects of TERT mutations. Besides, differences in genetic alterations and immunotherapy responses between TERT mutant and wild-type GBMs were also explored.

RESULTS

We found that TERT mutant and wild-type GBMs possessed similar initial clinic symptoms, circulating immune microenvironment and immunotherapy response. With respect to that in TERT wild-type GBMs, mutations in TERT resulted in higher levels of tumour-infiltrating neutrophils, prolonged coagulation time, worse chemotherapy response and poorer overall survival.

CONCLUSION

Mutations in TERT alter the local immune environment and decrease the sensitivity of GBM to chemotherapy.

Hyperbaric oxygen therapy restores cognitive function and hippocampal pathologies in both aging and aging-obese rats

The population of obese-elderly has increased prominently around the world. Both aging and obesity are major factors of neurodegeneration. The present study hypothesizes that HBOT attenuates metabolic disturbance, cognitive decline, hippocampal pathologies in aging and aging-obese model. Sixty Wistar rats were separated into 2 groups to receive normal-diet (ND) or high-fat diet (HFD) for 22 weeks. At week 13, ND rats were divided into two subgroups to receive vehicle (0.9 % NSS, s.c) or d-gal (150 mg/kg/d, s.c) for total 10 weeks. HFD rats were injected only d-gal (150 mg/kg/d, s.c; HFDD) for total 10 weeks. At week 20, rats in each subgroup were given sham-treatment (1ATA, 80 L/min, 80 min/day), or HBOT (2ATA, pure O₂, 250 L/min, 80 min/day) for 14 days. Novel object location test, metabolic parameters, and hippocampal pathologies were determined after HBOT. d-gal induced insulin resistance, increased oxidative stress, autophagy impairment, microglial hyperactivation, apoptosis, synaptic dysplasticity which resulted in cognitive impairment. d-gal-treated HFD-fed rats had the highest levels of oxidative stress, apoptosis, dendritic spine loss. HBOT attenuated insulin resistance, cognitive impairment, hippocampal aging and pathologies in both models. These findings suggest that HBOT restored insulin sensitivity, hippocampal functions, cognition in aging and aging-obese models.

Alterations in telomere length and mitochondrial DNA copy number in human lymphocytes on short-term exposure to moderate hypoxia

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Exposure to moderate hypoxia for 24 h significantly increased telomere length.

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Telomere elongation is related to the duration of hypoxia exposure.

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Mitochondrial DNA copy number was unaffected by hypoxia exposure.

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Mitochondrial DNA copy number is a more stable marker than telomere length alteration under hypoxia.

Hypoxia is related to a variety of diseases, such as cardiovascular and inflammatory diseases and various cancers. Telomere length (TL) may vary according to the hypoxia level and cell types. To the best of our knowledge, no study has investigated the effect of moderate hypoxia on TL and mitochondrial DNA copy number (mtDNAcn) in human lymphocytes. Therefore, in this study, we analyzed the effect of moderate hypoxia on TL in correlation with mtDNAcn. This study included 32 healthy male nonsmoker’s subjects; in this cohort, we had previously studied sister chromatid exchange and microsatellite instability. Blood samples from each subject were divided into three groups: a control group and two experimental groups exposed to moderate hypoxia for 12 or 24 h. Relative TL and mtDNAcn were measured by a quantitative real-time polymerase chain reaction. The TL in the control group did not significantly differ from that in the experimental group subjected to hypoxia for 12 h; however, the TL in the 24 h hypoxia–treated experimental group was significantly higher than that in the control group. The correlation between TL and mtDNAcn was not statistically significant in the two hypoxic states. The increase in TL was observed on exposure to hypoxia for 24 h and not for 12 h; thus, the findings suggest that telomere elongation is related to hypoxia exposure duration. The mtDNAcn in the two experimental groups did not significantly differ from that in the control group. These observations suggest that mtDNAcn alterations show more genetic stability than TL alterations. To the best of our knowledge, this is the first in vitro study on human lymphocytes reporting an increase in TL and no alteration in mtDNAcn after short-time exposure to moderate hypoxia.

SRT1720-induced activation of SIRT1 alleviates vascular smooth muscle cell senescence through PKA-dependent phosphorylation of AMPKα at Ser485

Aging is a major risk factor for hypertension and atherosclerosis, and vascular smooth muscle cell (VSMC) senescence can promote aging‐related vascular diseases. Sirtuin‐1 (SIRT1) and AMP‐activated protein kinase (AMPK) were previously reported to modulate vascular senescence; however, its effects have not been well characterized. To determine the nature of the interaction between SIRT1 and AMPK in VSMC senescence, we investigated the effects of SRT1720 on its downstream targets of SIRT1 and the phosphorylation of AMPKα at Ser485. During Adriamycin‐induced VSMC senescence, SRT1720 increased the activity of SIRT1 and AMPKα phosphorylation at Ser485 via the cAMP–protein kinase A (PKA) pathway. Telomere length and telomerase reverse transcriptase expression were increased by SIRT1 activation with SRT1720. Taken together, these data show that activation of the SIRT1/cAMP–PKA/p‐AMPKα (Ser485) pathway may be an effective antisenescence mechanism for VSMCs.

Hypoxia Causes Transgenerational Impairment of Ovarian Development and Hatching Success in Fish

Hypoxia is a pressing environmental problem in both marine and freshwater ecosystems globally, and this problem will be further exacerbated by global warming in the coming decades. Recently, we reported that hypoxia can cause transgenerational impairment of sperm quality and quantity in fish (in F0, F1, and F2 generations) through DNA methylome modifications. Here, we provide evidence that female fish ( Oryzias melastigma) exposed to hypoxia exhibit reproductive impairments (follicle atresia and retarded oocyte development), leading to a drastic reduction in hatching success in the F2 generation of the transgenerational group, although they have never been exposed to hypoxia. Further analyses show that the observed transgenerational impairments in ovarian functions are related to changes in the DNA methylation and expression pattern of two gene clusters that are closely associated with stress-induced cell cycle arrest and cell apoptosis. The observed epigenetic and transgenerational alterations suggest that hypoxia may pose a significant threat to the sustainability of natural fish populations.

Telomere elongation protects heart and lung tissue cells from fatal damage in rats exposed to severe hypoxia

Background

The effects of acute hypoxia at high altitude on the telomere length of the cells in the heart and lung tissues remain unclear. This study aimed to investigate the change in telomere length of rat heart and lung tissue cells in response to acute exposure to severe hypoxia and its role in hypoxia-induced damage to heart and lung tissues.

Methods

Forty male Wistar rats (6-week old) were randomized into control group (n = 10) and hypoxia group (n = 30). Rats in control group were kept at an altitude of 1500 m, while rats in hypoxia group were exposed to simulated hypoxia with an altitude of 5000 m in a low-pressure oxygen chamber for 1, 3, and 7 days (n = 10). The left ventricular and right middle lobe tissues of each rat were collected for measurement of telomere length and reactive oxygen species (ROS) content, and the mRNA and protein levels of telomerase reverse transcriptase (TERT), hypoxia-inducible factor1α (HIF-1α), and hypoxia-inducible factor1α (HIF-2α).

Results

Increased exposure to hypoxia damaged rat heart and lung tissue cells and increased ROS production and telomere length. The mRNA and protein levels of TERT and HIF-1α were significantly higher in rats exposed to hypoxia and increased with prolonged exposure; mRNA and protein levels of HIF-2α increased only in rats exposed to hypoxia for 7 days. TERT was positively correlated with telomere length and the levels of HIF-1α but not HIF-2α.

Conclusions

Acute exposure to severe hypoxia causes damage to heart and lung tissues due to the production of ROS but promotes telomere length and adaptive response by upregulating TERT and HIF-1α, which protect heart and lung tissue cells from fatal damage.

Elevated Vasodilatory Cyclases and Shorter Telomere Length Contribute to High-Altitude Pulmonary Edema

Rain, Manjari, Himanshi Chaudhary, Ritushree Kukreti, Tashi Thinlas, Ghulam Mohammad, and Qadar Pasha. Elevated vasodilatory cyclases and shorter telomere length contribute to high-altitude pulmonary edema. High Alt Med Biol. 19:60-68, 2018.

AIM

High-altitude (HA) genetics is complex with respect to health and disease (HA pulmonary edema i.e., HAPE). Based on the widely recognized fact that oxidative stress is a major trigger of several physiological processes, this study was designed to establish the significance of vasodilatory cyclases and telomere length in HA physiology. The study was performed in three groups, namely HAPE-free sojourners (HAPE-f, n = 150), HAPE patients (HAPE-p, n = 150), and healthy highland natives or highlanders (HLs, n = 150). Variations in soluble guanylyl cyclase β1-subunit (GUCY1B3) and adenylyl cyclase type 6 (ADCY6) were genotyped by the SNaPshot method and/or Fluidigm SNP type genotyping. Plasma GUCY1B3 and ADCY6 levels were estimated using ELISA, and relative telomere length was estimated by qRT-PCR.

RESULTS

The rs7638AA genotype was over-represented in HLs compared with HAPE-f and HAPE-p (p = 0.035 and p = 0.012, respectively). Similarly, the rs7638A allele was prevalent in HLs compared with both groups, but significance was attained against HAPE-p (p = 0.012). Significantly elevated plasma levels of GUCY1B3 and ADCY6 were obtained in HAPE-p compared with HAPE-f (p = 0.001 and p = 0.006, respectively) and HLs (p = 3.31E-05 and p = 0.05, respectively). Shorter telomere length was observed in HAPE-p compared with HAPE-f (p > 0.05) and HLs (p = 0.017).

CONCLUSION

Elevated cyclases and shorter telomere length associate with HAPE pathophysiology.

Telomere length-related gene ACYP2 polymorphism is associated with the risk of HAPE in Chinese Han population

BACKGROUND

High altitude pulmonary edema (HAPE) is a type of pneumonedema that mostly occurs under conditions such as high altitude, rapid ascent and hypoxia, amongst others. The ACYP2 polymorphism is suggested to be associated with mean telomere length, and telomere length is significantly longer at a moderate attitude than at sea-level or at simulated high attitude. The present study aimed to determine whethher there is any association between ACYP2 polymorphism and the risk of HAPE.

METHODS

A total of 265 patients and 303 healthy controls were enrolled in our case-control study. Six SNPs were selected and genotyped using the Sequenom MassARRAY method. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by unconditional logistic regression with adjustment for gender and age.

RESULTS

Using chi-squared tests, we found that the minor allele G of rs11896604 is significantly associated with a decreased risk of HAPE [odds ratio (OR) = 0.87, 95% confidence interval (CI) = 0.65-1.16, p = 0.048]. We also found that the 'A/A' genotype of rs12615793 is associated with a decreased risk of HAPE based on the recessive model (OR =0.28; 95% CI = 0.09-0.88; p = 0.017). Additionally, the 'G/G' genotype of rs11896604 was found to be associated with a decreased risk of HAPE based on the codominant model (OR =0.26; 95% CI = 0.08-0.79; p = 0.025) and recessive model (OR =0.25; 95% CI = 0.08-0.77; p = 0.007). However, only rs11896604 remained significant after Bonferroni correction (p < 0.0083).

CONCLUSIONS

The present study found that the ACYP2 gene polymorphism significantly decreased the risk of HAPE. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Association between regulator of telomere elongation helicase1 (RTEL1) gene and HAPE risk: A case-control study

High altitude pulmonary edema (HAPE) is a paradigm of pulmonary edema. Mutations in regulator of telomere elongation helicase1 (RTEL1) represent an important contributor to risk for pulmonary fibrosis. However, little information is found about the association between RTEL1 and HAPE risk. The present study was undertaken to tentatively explore the potential relation between single-nucleotide polymorphisms (SNPs) in RTEL1 and HAPE risk in Chinese Han population. A total of 265 HAPE patients and 303 healthy controls were included in our case-control study. Four SNPs in RTEL1 were selected and genotyped using the Sequenom MassARRAY method. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by unconditional logistic regression with adjustment for gender and age. All P values were Bonferroni corrected, and statistical significance was set at P < .0025 (.05/20). In allelic model analysis, we found that the allele "G" of rs6089953 and rs6010621 and the allele "A" of rs2297441 were associated with decreased risk of HAPE. In the genetic model analysis, we found that rs6010621, rs6089953, and rs2297441 were relevant to decreased HAPE risk under dominant model (rs6010621: OR = 0.55; 95% CI = 0.39-0.78; P = .001; rs6089953: OR = 0.68; 95% CI = 0.48-0.96; P = .027; rs2297441: OR = 0.63; 95% CI = 0.45-0.89; P = .008, respectively) and additive model (rs6010621: OR = 0.51; 95% CI = 0.46-0.81; P < .001; rs6089953: OR = 0.72; 95% CI = 0.55-0.95; P = .022; rs2297441: OR = 0.73; 95% CI = 0.57-0.95; P = .019, respectively). SNPs rs6010621 remained significant after Bonferroni correction (P < .0025). In addition, haplotype "GG, GT, AT" of rs6089953-rs6010621 were detected significantly associated with HAPE risk (P < .05), haplotype "GG" remained significant after Bonferroni correction (P < .0025). Our findings provide new evidence for the association between SNPs in RTEL1 and a decreased risk HAPE in the Chinese population. The results need further confirmation.

Mechanisms of fetal epigenetics that determine telomere dynamics and health span in adulthood

Advances in epigenetics now enable us to better understand environmental influences on the genetic background of human diseases. This refers especially to fetal development where an adverse intrauterine environment impacts oxygen and nutrient supply to the fetus. Recently, differences in telomere length and telomere loss dynamics among individuals born with intrauterine growth restriction compared to normal controls have been described. In this paper we propose possible molecular mechanisms that (pre)program telomere epigenetics during pregnancy. This programming sets differences in telomere lengths and dynamics of telomere shortening in adulthood and therefore dictates the dynamics of aging and morbidity in later life.

Non-linear actions of physiological agents: Finite disarrangements elicit fitness benefits

Finite disarrangements of important (vital) physiological agents and nutrients can induce plethora of beneficial effects, exceeding mere attenuation of the specific stress. Such response to disrupted homeostasis appears to be universally conserved among species. The underlying mechanism of improved fitness and longevity, when physiological agents act outside their normal range is similar to hormesis, a phenomenon whereby toxins elicit beneficial effects at low doses. Due to similarity with such non-linear response to toxins described with J-shaped curve, we have coined a new term “mirror J-shaped curves” for non-linear response to finite disarrangement of physiological agents. Examples from the clinical trials and basic research are provided, along with the unifying mechanisms that tie classical non-linear response to toxins with the non-linear response to physiological agents (glucose, oxygen, osmolarity, thermal energy, calcium, body mass, calorie intake and exercise). Reactive oxygen species and cytosolic calcium seem to be common triggers of signaling pathways that result in these beneficial effects. Awareness of such phenomena and exploring underlying mechanisms can help physicians in their everyday practice. It can also benefit researchers when designing studies and interpreting growing number of scientific data showing non-linear responses to physiological agents.

Association between genetic polymorphism of telomere-associated gene ACYP2 and the risk of HAPE among the Chinese Han population: A Case-control study

High-altitude pulmonary edema (HAPE) is a hypoxia-induced, life-threatening, pulmonary edema, which is characterized by exaggerated pulmonary hypertension caused by stress failure. ACYP2 was found to associated with telomere length, the aim of this study was to identify whether ACYP2 polymorphisms increase or decrease HAPE risk in the Chinese Han individuals.In present study, we have genotyped 7 single-nucleotide polymorphisms (SNPs) in ACYP2 to determine the haplotypes in a case-control study with 265 HAPE patients and 303 healthy individuals. Genotypes were determined using the Sequenom MassARRAY method. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression with adjustment for gender and age. We found 3 SNPs yielded significant evidence for association with HAPE risk which had not been investigated before. Rs6713088 was found to have a 1.85- and 1.30-fold increased risk of HAPE in the recessive and additive model. The GT of rs843752 also conferred an increased risk of HAPE (GT/TT: OR = 1.51, 95% CI: 1.05-2.16, P = 0.026) and the genotype frequency distributions of rs843752 had significant difference between cases and controls. The CC genotype of rs17045754 had a protect effect on HAPE patients, and it was found to have a 0.29-fold reduced risk of HAPE in the recessive model.Although additional, larger population-based studies are needed to confirm these findings, our study shed light on the association between ACYP2 variant and HAPE risk in Han Chinese population for the first time.