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Expression of telomerase reverse transcriptase positively correlates with duration of lithium treatment in bipolar disorder.

ABSTRACT: Bipolar disorder (BD) may be associated with accelerated cellular aging. However, previous studies on telomere length (TL), an important biomarker of cellular aging, have yielded mixed results in BD. We aimed to evaluate the hypothesis that BD is associated with telomere shortening and whether this is counteracted by long-term lithium treatment. We also sought to determine whether long-term lithium treatment is associated with increased expression of telomerase reverse transcriptase (TERT), the catalytic subunit of telomerase. We determined TL and TERT expression in 100 BD I patients and 100 healthy controls. We also genotyped three single nucleotide polymorphisms associated with TL. TERT expression was significantly increased in BD I patients currently on lithium treatment. TERT expression was also significantly positively correlated with duration of lithium treatment in patients treated for 24 months or more. However, we did not find any significant effect of lithium treatment on TL. Neither did we find significant differences in TL between BD patients and controls. We suggest that long-term lithium treatment is associated with an increase in the expression of TERT. We hypothesize that an increase in TERT expression may contribute to lithium's mood stabilizing and neuroprotective properties by improving mitochondrial function and decreasing oxidative stress.

SUBMITTER: Lundberg M

PROVIDER: S-EPMC7334059 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Telomerase reverse transcriptase moonlights: Therapeutic targets beyond telomerase.

Project description:Telomeres, the repetitive sequences at chromosomal ends, protect intact chromosomes. Telomeres progressively shorten through successive rounds of cell divisions, and critically shortened telomeres trigger senescence and apoptosis. The enzyme that elongates telomeres and maintains their structure is known as telomerase. The catalytic subunit of this enzyme (telomerase reverse transcriptase [TERT]) is expressed at a high level in malignant cells, but at a very low level in normal cells. Although telomerase activity was long believed to be the only function of TERT, emerging evidence indicates that TERT plays roles beyond telomeres. For example, TERT contributes to stem cell maintenance and cell reprogramming processes in a manner independent of its canonical function. Even some types of splice variants that lack the telomerase catalytic domains exhibit the functions in a manner that does not depend on telomerase activity. We recently demonstrated that the RNA-dependent RNA polymerase (RdRP) activity of TERT is involved in regulation of gene silencing and heterochromatic transcription. Moreover, TERT RdRP activity is mediated by a newly identified complex, distinct from the authentic telomerase complex, that plays a role in cancer stem cells in a telomere maintenance independent manner. TERT has attracted interest as a molecular target for anticancer treatment, but previous efforts aimed at developing novel therapeutic strategies focused only on the canonical function of TERT. However, accumulating evidence about the non-canonical functions of TERT led us to speculate that the functions other than telomerase might be therapeutic targets as well. In this review, we discuss the non-canonical functions of TERT and their potential applications for anticancer treatment.

| S-EPMC4714691 | biostudies-literature

A telomerase holoenzyme protein enhances telomerase RNA assembly with telomerase reverse transcriptase.

Project description:Telomerase maintains the simple sequence repeats at chromosome ends, protecting cells from genomic rearrangement, proliferative senescence and death. The telomerase reverse transcriptase (TERT) and telomerase RNA (TER) alone can assemble into active enzyme in a heterologous cell extract, but the physiological process of telomerase biogenesis is more complex. The endogenous accumulation of Tetrahymena thermophila TERT and TER requires an additional telomerase holoenzyme protein, p65. Here, we reconstitute this cellular pathway for telomerase ribonucleoprotein biogenesis in vitro. We demonstrate that tandem RNA interaction domains in p65 recognize the sequence of the TER 3' stem. Notably, the p65-TER complex recruits TERT much more efficiently than does TER alone. Using bacterially expressed p65 and TERT polypeptides, we show that p65 enhances TERT-TER interaction by a mechanism involving a conserved bulge in the protein-bridging TER molecule. These findings reveal a pathway for telomerase holoenzyme biogenesis that preassembles TER for TERT recruitment.

| S-EPMC2913471 | biostudies-other

Immunophenotypes associated with bipolar disorder and lithium treatment.

Project description:Immune dysfunction is implicated in the etiology of bipolar disorder. The single-nucleotide polymorphism rs17026688 in the gene encoding glutamate decarboxylase-like protein 1 (GADL1) has been found to be associated with lithium response in Han Chinese patients with bipolar I disorder (BDI). However, whether patients with GADL1 polymorphisms have different immunophenotypes is unknown. To address this issue, differences in the immune profiles based on analysis of peripheral blood mononuclear cells (PBMCs) were compared among BDI patients and healthy controls who lack or carry the T allele of rs17026688. BDI patients had significantly higher percentages of total T cells, CD4+ T cells, activated B cells, and monocytes than healthy controls, suggesting that immunologic imbalance might be involved in BDI development or progression. Treatment of BDI patients-derived PBMCs with lithium in vitro increased the percentage of CD14+ monocytes and dendritic cells, suggesting that lithium plays an immunomodulatory role in CD14+ monocytes and dendritic cells. Among BDI patients, non-T carriers had a significantly higher percentage of CD11b+/CD33lo/HLA-DR- myeloid-derived suppressor cells than T carriers. Moreover, only T carriers exhibited differential sensitivity to lithium therapeutic use with respect to the percentage of myeloid cells. These findings suggest that rs17026688 polymorphisms in GADL1 are associated with immune dysfunction in BDI patients.

| S-EPMC6877517 | biostudies-literature

Human telomerase reverse transcriptase positively regulates mitophagy by inhibiting the processing and cytoplasmic release of mitochondrial PINK1.

Project description:Mutations in the phosphatase and tensin homologue-induced putative kinase 1 (PINK1) gene have been linked to an early-onset autosomal recessive form of familial Parkinson's disease (PD). PINK1, a mitochondrial serine/threonine-protein kinase, plays an important role in clearing defective mitochondria by mitophagy - the selective removal of mitochondria through autophagy. Evidence suggests that alteration of the PINK1 pathway contributes to the pathogenesis of PD, but the mechanisms by which the PINK1 pathway regulates mitochondrial quality control through mitophagy remain unclear. Human telomerase reverse transcriptase (hTERT) is a catalytic subunit of telomerase that functions in telomere maintenance as well as several non-telomeric activities. For example, hTERT has been associated with cellular immortalization, cell growth control, and mitochondrial regulation. We determined that hTERT negatively regulates the cleavage and cytosolic processing of PINK1 and enhances its mitochondrial localization by inhibiting mitochondrial processing peptidase ? (MPP?). Consequently, hTERT promotes mitophagy following carbonyl cyanide m-chlorophenylhydrazone (CCCP)-induced mitochondrial dysfunction and improves the function of damaged mitochondria by modulating PINK1. These findings suggest that hTERT positively regulates PINK1 function, leading to increased mitophagy following mitochondrial damage.

| S-EPMC7280311 | biostudies-literature

Panic disorder aging characteristics: The role of telomerase reverse transcriptase gene and brain function.

Project description:Panic disorder (PD) causes serious functional damage and disability and accelerates the process of individual aging. The pathological basis of PD is the same as that of age-related diseases, which is proposed as a new viewpoint in recent years. Memory decline and social functional impairment are common manifestations of accelerated aging in PD. The function of telomerase reverse transcriptase (TERT) and telomere length (TL) is abnormal in patients with aging and PD. However, the molecular mechanism behind remains unclear. The purpose of this study was to explore the relationship between TERT gene expression (including DNA methylation) and the changes in PD aging characteristics (memory and social function). By TERT gene knockout mice, we found that loss of TERT attenuated the acquisition of recent fear memory during contextual fear conditioning. This study reported that a significantly lower methylation level of human TERT (hTERT) gene was detected in PD patients compared with healthy control and particularly decreased CpG methylation in the promoter region of hTERT was associated with the clinical characteristics in PD. Regional homogeneity (ReHo) analysis showed that the methylation of hTERT (cg1295648) influenced social function of PD patients through moderating the function of the left postcentral gyrus (PCG). This indicates that the hTERT gene may play an important role in the pathological basis of PD aging and may become a biological marker for evaluating PD aging. These findings provide multidimensional evidence for the underlying genetic and pathological mechanisms of PD.

| S-EPMC9389410 | biostudies-literature

Telomerase reverse transcriptase promotes stem cell competition through MYC

Project description:This SuperSeries is composed of the SubSeries listed below.

2024-07-11 | GSE145659 | GEO

Hepatitis B Virus-Telomerase Reverse Transcriptase Promoter Integration Harnesses Host ELF4, Resulting in Telomerase Reverse Transcriptase Gene Transcription in Hepatocellular Carcinoma.

Project description:Background and aimsHepatitis B virus (HBV) integrations are common in hepatocellular carcinoma (HCC). In particular, alterations of the telomerase reverse transcriptase (TERT) gene by HBV integrations are frequent; however, the molecular mechanism and functional consequence underlying TERT HBV integration are unclear.Approach and resultsWe adopted a targeted sequencing strategy to survey HBV integrations in human HBV-associated HCCs (n = 95). HBV integration at the TERT promoter was frequent (35.8%, n = 34/95) in HCC tumors and was associated with increased TERT mRNA expression and more aggressive tumor behavior. To investigate the functional importance of various integrated HBV components, we employed different luciferase reporter constructs and found that HBV enhancer I (EnhI) was the key viral component leading to TERT activation on integration at the TERT promoter. In addition, the orientation of the HBV integration at the TERT promoter further modulated the degree of TERT transcription activation in HCC cell lines and patients' HCCs. Furthermore, we performed array-based small interfering RNA library functional screening to interrogate the potential major transcription factors that physically interacted with HBV and investigated the cis-activation of host TERT gene transcription on viral integration. We identified a molecular mechanism of TERT activation through the E74 like ETS transcription factor 4 (ELF4), which normally could drive HBV gene transcription. ELF4 bound to the chimeric HBV EnhI at the TERT promoter, resulting in telomerase activation. Stable knockdown of ELF4 significantly reduced the TERT expression and sphere-forming ability in HCC cells.ConclusionsOur results reveal a cis-activating mechanism harnessing host ELF4 and HBV integrated at the TERT promoter and uncover how TERT HBV-integrated HCCs may achieve TERT activation in hepatocarcinogenesis.

| S-EPMC7898544 | biostudies-literature

Implications of telomerase reverse transcriptase in tumor metastasis.

Project description:Metastasis is the main culprit of the great majority of cancerrelated deaths. However, the complicated process of the invasion-metastasis cascade remains the least understood aspect of cancer biology. Telomerase plays a pivotal role in bypassing cellular senescence and sustaining the cancer progression by maintaining telomere homeostasis and genomic integrity. Telomerase reverse transcriptase (TERT) exerts a series of fundamental functions that are independent of its enzymatic cellular activity, including proliferation, inflammation, epithelia-mesenchymal transition (EMT), angiogenesis, DNA repair, and gene expression. Accumulating evidence indicates that TERT may facilitate most steps of the invasion-metastasis cascade. In this review, we summarize important advances that have revealed some of the mechanisms by which TERT facilitates tumor metastasis, providing an update on the non-canonical functions of telomerase beyond telomere maintaining. [BMB Reports 2020; 53(9): 458-465].

| S-EPMC7526981 | biostudies-literature

Diverse regulatory manners of human telomerase reverse transcriptase.

Project description:Human telomerase reverse transcriptase (hTERT) is the core subunit of human telomerase and plays important roles in human cancers. Aberrant expression of hTERT is closely associated with tumorigenesis, cancer cell stemness maintaining, cell proliferation, apoptosis inhibition, senescence evasion and metastasis. The molecular basis of hTERT regulation is highly complicated and consists of various layers. A deep and full-scale comprehension of the regulatory mechanisms of hTERT is pivotal in understanding the pathogenesis and searching for therapeutic approaches. In this review, we summarize the recent advances regarding the diverse regulatory mechanisms of hTERT, including the transcriptional (promoter mutation, promoter region methylation and histone acetylation), post-transcriptional (mRNA alternative splicing and non-coding RNAs) and post-translational levels (phosphorylation and ubiquitination), which may provide novel perspectives for further translational diagnosis or therapeutic strategies targeting hTERT.

| S-EPMC6560729 | biostudies-literature

Involvement of telomerase reverse transcriptase in heterochromatin maintenance.

Project description:In the fission yeast Schizosaccharomyces pombe, centromeric heterochromatin is maintained by an RNA-directed RNA polymerase complex (RDRC) and the RNA-induced transcriptional silencing (RITS) complex in a manner that depends on the generation of short interfering RNA. In association with the telomerase RNA component (TERC), the telomerase reverse transcriptase (TERT) forms telomerase and counteracts telomere attrition, and without TERC, TERT has been implicated in the regulation of heterochromatin at locations distinct from telomeres. Here, we describe a complex composed of human TERT (hTERT), Brahma-related gene 1 (BRG1), and nucleostemin (NS) that contributes to heterochromatin maintenance at centromeres and transposons. This complex produced double-stranded RNAs homologous to centromeric alpha-satellite (alphoid) repeat elements and transposons that were processed into small interfering RNAs targeted to these heterochromatic regions. These small interfering RNAs promoted heterochromatin assembly and mitotic progression in a manner dependent on the RNA interference machinery. These observations implicate the hTERT/BRG1/NS (TBN) complex in heterochromatin assembly at particular sites in the mammalian genome.

| S-EPMC3993606 | biostudies-literature

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