scholarly journals Alternative Lengthening of Telomeres (ALT) in Tumors and Pluripotent Stem Cells

Genes ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1030 ◽  
Author(s):  
Shuang Zhao ◽  
Feng Wang ◽  
Lin Liu
Keyword(s):  
Stem Cells ◽  
Cancer Cells ◽  
Telomere Length ◽  
Dna Sequences ◽  
Pluripotent Stem Cells ◽  
Telomerase Activity ◽  
Age Related ◽  
Alternative Lengthening ◽  
Damage Response ◽  
Length Regulation

A telomere consists of repeated DNA sequences (TTAGGG)n as part of a nucleoprotein structure at the end of the linear chromosome, and their progressive shortening induces DNA damage response (DDR) that triggers cellular senescence. The telomere can be maintained by telomerase activity (TA) in the majority of cancer cells (particularly cancer stem cells) and pluripotent stem cells (PSCs), which exhibit unlimited self-proliferation. However, some cells, such as telomerase-deficient cancer cells, can add telomeric repeats by an alternative lengthening of the telomeres (ALT) pathway, showing telomere length heterogeneity. In this review, we focus on the mechanisms of the ALT pathway and potential clinical implications. We also discuss the characteristics of telomeres in PSCs, thereby shedding light on the therapeutic significance of telomere length regulation in age-related diseases and regenerative medicine.

scholarly journals TERRA: A Novel Biomarker of Embryo Quality and Art Outcome

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 475
Author(s):  
Maria Santa Rocca ◽  
Ludovica Dusi ◽  
Andrea Di Nisio ◽  
Erminia Alviggi ◽  
Benedetta Iussig ◽  
...  
Keyword(s):  
Telomere Length ◽  
Dna Sequences ◽  
Male Fertility ◽  
Embryo Quality ◽  
Assisted Reproductive Technologies ◽  
Biological Clock ◽  
Reproductive Technologies ◽  
Age Related ◽  
Non Coding Rna ◽  
First Time

Telomeres are considered to be an internal biological clock, and their progressive shortening has been associated with the risk of age-related diseases and reproductive alterations. Over recent years, an increasing number of studies have focused on the association between telomere length and fertility, identifying sperm telomere length (STL) as a novel biomarker of male fertility. Although typically considered to be repeated DNA sequences, telomeres have recently been shown to also include a long non-coding RNA (lncRNA) known as TERRA (telomeric repeat-containing RNAs). Interestingly, males with idiopathic infertility show reduced testicular TERRA expression, suggesting a link between TERRA and male fertility. The aim of this study was to investigate the role of seminal TERRA expression in embryo quality. To this end, STL and TERRA expression were quantified by Real Time qPCR in the semen of 35 men who underwent assisted reproductive technologies (ART) and 30 fertile men. We found that TERRA expression in semen and STL was reduced in patients that underwent ART (both p < 0.001). Interestingly, TERRA and STL expressions were positively correlated (p = 0.010), and TERRA expression was positively associated with embryo quality (p < 0.001). These preliminary findings suggest a role for TERRA in the maintenance of sperm telomere integrity during gametogenesis, and for the first time, TERRA expression was found as a predictive factor for embryo quality in the setting of assisted reproduction.

scholarly journals Establishing a deeper understanding of the osteogenic differentiation of monolayer cultured human pluripotent stem cells using novel and detailed analyses

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ping Zhou ◽  
Jia-Min Shi ◽  
Jing-E Song ◽  
Yu Han ◽  
Hong-Jiao Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Osteogenic Differentiation ◽  
Pluripotent Stem Cells ◽  
Embryonic Stem ◽  
Telomerase Activity ◽  
Human Pluripotent Stem Cells ◽  
Cell Counting ◽  
Cell Type ◽  
Alizarin Red

Abstract Background Derivation of osteoblast-like cells from human pluripotent stem cells (hPSCs) is a popular topic in bone tissue engineering. Although many improvements have been achieved, the low induction efficiency because of spontaneous differentiation hampers their applications. To solve this problem, a detailed understanding of the osteogenic differentiation process of hPSCs is urgently needed. Methods Monolayer cultured human embryonic stem cells and human-induced pluripotent stem cells were differentiated in commonly applied serum-containing osteogenic medium for 35 days. In addition to traditional assays such as cell viability detection, reverse transcription-polymerase chain reaction, immunofluorescence, and alizarin red staining, we also applied studies of cell counting, cell telomerase activity, and flow cytometry as essential indicators to analyse the cell type changes in each week. Results The population of differentiated cells was quite heterogeneous throughout the 35 days of induction. Then, cell telomerase activity and cell cycle analyses have value in evaluating the cell type and tumourigenicity of the obtained cells. Finally, a dynamic map was made to integrate the analysis of these results during osteogenic differentiation of hPSCs, and the cell types at defined stages were concluded. Conclusions Our results lay the foundation to improve the in vitro osteogenic differentiation efficiency of hPSCs by supplementing with functional compounds at the desired stage, and then establishing a stepwise induction system in the future.

scholarly journals Telomere length set point regulation in human pluripotent stem cells critically depends on the shelterin protein TPP1

2020 ◽  
Vol 31 (23) ◽  
pp. 2583-2596
Author(s):  
John M. Boyle ◽  
Kelsey M. Hennick ◽  
Samuel G. Regalado ◽  
Jacob M. Vogan ◽  
Xiaozhu Zhang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Telomere Length ◽  
Pluripotent Stem Cells ◽  
Human Stem Cells ◽  
Set Point ◽  
Hypomorphic Allele ◽  
Point Control ◽  
Set Point Control ◽  
Stem Cell Lines

To better understand telomere length set point control in human stem cells, we generated knockout stem cell lines for TPP1 and contrasted their phenotypes with those of homozygous TPP1 L104A mutant stem cells. This comparison reveals that TPP1 L104A is not a hypomorphic allele but formally establishes TPP1 L104 as a dissociation of function mutant.

scholarly journals Opportunities for Antibody Discovery Using Human Pluripotent Stem Cells: Conservation of Oncofetal Targets

2019 ◽  
Vol 20 (22) ◽  
pp. 5752 ◽  
Author(s):  
Heng Liang Tan ◽  
Andre Choo
Keyword(s):  
Stem Cells ◽  
Cancer Cells ◽  
Pluripotent Stem Cells ◽  
Disease Modeling ◽  
Embryonic Stem ◽  
Oncofetal Antigens ◽  
Antibody Discovery ◽  
Induced Pluripotent ◽  
New Biomarkers

Pluripotent stem cells (PSCs) comprise both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). The application of pluripotent stem cells is divided into four main areas, namely: (i) regenerative therapy, (ii) the study and understanding of developmental biology, (iii) drug screening and toxicology and (iv) disease modeling. In this review, we describe a new opportunity for PSCs, the discovery of new biomarkers and generating antibodies against these biomarkers. PSCs are good sources of immunogen for raising monoclonal antibodies (mAbs) because of the conservation of oncofetal antigens between PSCs and cancer cells. Hence mAbs generated using PSCs can potentially be applied in two different fields. First, these mAbs can be used in regenerative cell therapy to characterize the PSCs. In addition, the mAbs can be used to separate or eliminate contaminating or residual undifferentiated PSCs from the differentiated cell product. This step is critical as undifferentiated PSCs can form teratomas in vivo. The mAbs generated against PSCs can also be used in the field of oncology. Here, novel targets can be identified and the mAbs developed as targeted therapy to kill the cancer cells. Conversely, as new and novel oncofetal biomarkers are discovered on PSCs, cancer mAbs that are already approved by the FDA can be repurposed for regenerative medicine, thus expediting the route to the clinics.

scholarly journals Telomere Length in Valve Tissue Is Shorter in Individuals With Aortic Stenosis and in Calcified Valve Areas

2021 ◽  
Vol 9 ◽  
Author(s):  
Ilona Saraieva ◽  
Athanase Benetos ◽  
Carlos Labat ◽  
Anders Franco-Cereceda ◽  
Magnus Bäck ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Telomere Length ◽  
Telomerase Activity ◽  
Aortic Valves ◽  
Fragment Analysis ◽  
Replacement Surgery ◽  
Age Related ◽  
Amplification Protocol ◽  
Telomere Restriction Fragment

BackgroundShort telomere length (TL) is associated with age-related diseases, in particular cardiovascular diseases. However, whether the onset and course of aortic stenosis (AS) is linked to TL in aortic valves remains unknown.ObjectivesTo assess telomere dynamics (TL and telomerase activity) in aortic valves and the possible implication of TL in onset and course of AS.MethodsDNA was extracted from aortic valves obtained from 55 patients (78.2% men; age, 37–79 years), who had undergone replacement surgery due to AS (AS group, n = 32), aortic valve regurgitation and aortic dilation (Non-AS group, n = 23). TL was measured by telomere restriction fragment analysis (TRF) in calcified and non-calcified aortic valve areas. Telomerase activity was evaluated using telomerase repeat amplification protocol (TRAP) in protein extracts from non-calcified and calcified areas of valves obtained from 4 additional patients (50% men; age, 27–70 years).ResultsTL was shorter in calcified aortic valve areas in comparison to non-calcified areas (n = 31, 8.58 ± 0.73 kb vs. 8.12 ± 0.75 kb, p &lt; 0.0001), whereas telomerase activity was not detected in any of those areas. Moreover, patients from AS group displayed shorter telomeres in non-calcified areas than those from the Non-AS group (8.40 ± 0.64 kb vs. 8.85 ± 0.65, p = 0.01).ConclusionsShort telomeres in aortic valves may participate in the development of AS, while concurrently the calcification process seems to promote further local decrease of TL in calcified areas of valves.

Epigenetic features in regulation of telomeres and telomerase in stem cells

2021 ◽  
Author(s):  
Fatma Dogan ◽  
Nicholas R. Forsyth
Keyword(s):  
Stem Cells ◽  
Telomere Length ◽  
Cell Biology ◽  
Replicative Senescence ◽  
Telomerase Activity ◽  
Cell Phenotype ◽  
Tissue Degeneration ◽  
Unique System ◽  
Telomerase Regulation

The epigenetic nature of telomeres is still controversial and different human cell lines might show diverse histone marks at telomeres. Epigenetic modifications regulate telomere length and telomerase activity that influence telomere structure and maintenance. Telomerase is responsible for telomere elongation and maintenance and is minimally composed of the catalytic protein component, telomerase reverse transcriptase (TERT) and template forming RNA component, telomerase RNA (TERC). TERT promoter mutations may underpin some telomerase activation but regulation of the gene is not completely understood due to the complex interplay of epigenetic, transcriptional, and posttranscriptional modifications. Pluripotent stem cells (PSCs) can maintain an indefinite, immortal, proliferation potential through their endogenous telomerase activity, maintenance of telomere length, and a bypass of replicative senescence in vitro. Differentiation of PSCs results in silencing of the TERT gene and an overall reversion to a mortal, somatic cell phenotype. The precise mechanisms for this controlled transcriptional silencing are complex. Promoter methylation has been suggested to be associated with epigenetic control of telomerase regulation which presents an important prospect for understanding cancer and stem cell biology. Control of down-regulation of telomerase during differentiation of PSCs provides a convenient model for the study of its endogenous regulation. Telomerase reactivation has the potential to reverse tissue degeneration, drive repair, and form a component of future tissue engineering strategies. Taken together it becomes clear that PSCs provide a unique system to understand telomerase regulation fully and drive this knowledge forward into aging and therapeutic application.

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