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Sutterlüty H, Bargl M, Holzmann K. Quantifying telomere transcripts as tool to improve risk assessment for genetic instability and genotoxicity. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2023; 891:503690. [PMID: 37770147 DOI: 10.1016/j.mrgentox.2023.503690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/18/2023] [Accepted: 09/04/2023] [Indexed: 10/03/2023]
Abstract
Telomere repeat-containing RNAs (TERRA) are transcribed from telomeres as long non-coding RNAs and are part of the telomere structure with protective function. The genetic stability of cells requires telomeric repeats at the ends of chromosomes. Maintenance of telomere length (TL) is essential for proliferative capacity and chromosomal integrity. In contrast, telomere shortening is a recognized risk factor for carcinogenesis and a biomarker of aging due to the cumulative effects of environmental exposures and life experiences such as trauma or stress. In this context, telomere repeats are lost due to cell proliferation, but are also susceptible to stress factors including reactive oxygen species (ROS) inducing oxidative base damage. Quantitative PCR (qPCR) of genomic DNA is an established method to analyze TL as a tool to detect genotoxic events. That same qPCR method can be applied to RNA converted into cDNA to quantify TERRA as a useful tool to perform high-throughput screenings. This short review summarizes relevant qPCR studies using both TL and TERRA quantification, provides an overall view of the molecular mechanisms of telomere protection against ROS by TERRA, and summarizes the presented studies comparing the results at DNA and RNA levels, which indicate that fluctuations at transcript level might reflect a short-term response. Therefore, we conclude that performing both of these measurements together will improve genotoxicity studies.
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Affiliation(s)
- Hedwig Sutterlüty
- Center for Cancer Research, Comprehensive Cancer Center, Medical University Vienna, Borschkegasse 8a, A-1090 Vienna, Austria
| | - Maximilian Bargl
- Center for Cancer Research, Comprehensive Cancer Center, Medical University Vienna, Borschkegasse 8a, A-1090 Vienna, Austria
| | - Klaus Holzmann
- Center for Cancer Research, Comprehensive Cancer Center, Medical University Vienna, Borschkegasse 8a, A-1090 Vienna, Austria.
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Dahlgren PN, Bishop K, Dey S, Herbert BS, Tanaka H. Development of a New Monochrome Multiplex qPCR Method for Relative Telomere Length Measurement in Cancer. Neoplasia 2018; 20:425-431. [PMID: 29573637 PMCID: PMC5915991 DOI: 10.1016/j.neo.2018.02.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 02/14/2018] [Accepted: 02/19/2018] [Indexed: 01/30/2023] Open
Abstract
Excess telomere shortening has been observed in most cancer cells. The telomere quantitative polymerase chain reaction (qPCR) assay has become an important tool for epidemiological studies examining the effects of aging, stress, and other factors on the length of telomeres. Current telomere qPCR methods analyze the relative length of telomeres by amplifying telomere sequence products and normalizing with single-copy gene products. However, the current telomere qPCR does not always reflect absolute telomere length in cancer DNA. Because of genomic instability in cancer cells, we hypothesized that the use of single-copy genes (scg) is less accurate for normalizing data in cancer DNA and that new primer sets are required to better represent relative telomere length in cancer DNA. We first confirmed that cancer cells had a different copy ratio among different scg, implying that DNA is aneuploid. By using the new primer sets that amplify multiple-copy sequences (mcs) throughout the genome, the telomere qPCR results showed that the mcs primers were interchangeable with the scg primers as reference primers in normal DNA. By comparing results from the traditional southern blotting method (as kilobases) and results from monochrome multiplex qPCR using the mcs primers (as T/M ratios), we verified that the T/M ratio is highly correlated with absolute telomere length from the southern blot analysis. Together, the mcs primers were able to represent the telomere lengths accurately in cancer DNA samples. These results would allow for analyses of telomeres within cancerous DNA and the development of new, less invasive diagnostic tools for cancer.
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Affiliation(s)
- Paige N Dahlgren
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Kanokwan Bishop
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Shatovisha Dey
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Brittney-Shea Herbert
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Hiromi Tanaka
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN.
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González-Giraldo Y, Forero DA, Echeverria V, Gonzalez J, Ávila-Rodriguez M, Garcia-Segura LM, Barreto GE. Neuroprotective effects of the catalytic subunit of telomerase: A potential therapeutic target in the central nervous system. Ageing Res Rev 2016; 28:37-45. [PMID: 27095058 DOI: 10.1016/j.arr.2016.04.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 04/12/2016] [Accepted: 04/13/2016] [Indexed: 12/15/2022]
Abstract
Senescence plays an important role in neurodegenerative diseases and involves key molecular changes induced by several mechanisms such as oxidative stress, telomere shortening and DNA damage. Potential therapeutic strategies directed to counteract these molecular changes are of great interest for the prevention of the neurodegenerative process. Telomerase is a ribonucleoprotein composed of a catalytic subunit (TERT) and a RNA subunit (TERC). It is known that the telomerase is involved in the maintenance of telomere length and is a highly expressed protein in embryonic stages and decreases in adult cells. In the last decade, a growing number of studies have shown that TERT has neuroprotective effects in cellular and animal models after a brain injury. Significantly, differences in TERT expression between controls and patients with major depressive disorder have been observed. More recently, TERT has been associated with the decrease in reactive oxygen species and DNA protection in mitochondria of neurons. In this review, we highlight the role of TERT in some neurodegenerative disorders and discuss some studies focusing on this protein as a potential target for neuroprotective therapies.
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Affiliation(s)
- Yeimy González-Giraldo
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - Diego A Forero
- Laboratory of Neuropsychiatric Genetics, Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, Bogotá, Colombia
| | - Valentina Echeverria
- Facultad de Ciencias de la Salud, Universidad San Sebastián, Lientur 1457, Concepción, Chile
| | - Janneth Gonzalez
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | | | | | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia; Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile; Universidad Científica del Sur, Lima, Peru.
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Novel Luminex Assay for Telomere Repeat Mass Does Not Show Well Position Effects Like qPCR. PLoS One 2016; 11:e0155548. [PMID: 27182778 PMCID: PMC4868509 DOI: 10.1371/journal.pone.0155548] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 04/29/2016] [Indexed: 12/03/2022] Open
Abstract
Telomere length is a potential biomarker of aging and risk for age-related diseases. For measurement of relative telomere repeat mass (TRM), qPCR is typically used primarily due to its low cost and low DNA input. But the position of the sample on a plate often impacts the qPCR-based TRM measurement. Recently we developed a novel, probe-based Luminex assay for TRM that requires ~50ng DNA and involves no DNA amplification. Here we report, for the first time, a comparison among TRM measurements obtained from (a) two singleplex qPCR assays (using two different primer sets), (b) a multiplex qPCR assay, and (c) our novel Luminex assay. Our comparison is focused on characterizing the effects of sample positioning on TRM measurement. For qPCR, DNA samples from two individuals (K and F) were placed in 48 wells of a 96-well plate. For each singleplex qPCR assay, we used two plates (one for Telomere and one for Reference gene). For the multiplex qPCR and the Luminex assay, the telomere and the reference genes were assayed from the same well. The coefficient of variation (CV) of the TRM for Luminex (7.2 to 8.4%) was consistently lower than singleplex qPCR (11.4 to 14.9%) and multiplex qPCR (19.7 to 24.3%). In all three qPCR assays the DNA samples in the left- and right-most columns showed significantly lower TRM than the samples towards the center, which was not the case for the Luminex assay (p = 0.83). For singleplex qPCR, 30.5% of the variation in TL was explained by column-to-column variation and 0.82 to 27.9% was explained by sample-to-sample variation. In contrast, only 5.8% of the variation in TRM for the Luminex assay was explained by column-to column variation and 50.4% was explained by sample-to-sample variation. Our novel Luminex assay for TRM had good precision and did not show the well position effects of the sample that were seen in all three of the qPCR assays that were tested.
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Forero DA, González-Giraldo Y, López-Quintero C, Castro-Vega LJ, Barreto GE, Perry G. Telomere length in Parkinson's disease: A meta-analysis. Exp Gerontol 2016; 75:53-5. [PMID: 26772888 DOI: 10.1016/j.exger.2016.01.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 12/24/2015] [Accepted: 01/04/2016] [Indexed: 12/17/2022]
Abstract
Parkinson's disease (PD) is a common and severe movement disorder. Differences in telomere length (TL) have been reported as possible risk factors for several neuropsychiatric disorders, including PD. Results from published studies for TL in PD are inconsistent, highlighting the need for a meta-analysis. In the current work, a meta-analysis of published studies for TL in PD was carried out. PubMed, Web of Science and Google Scholar databases were used to identify relevant articles that reported TL in groups of PD patients and controls. A random-effects model was used for meta-analytical procedures. The meta-analysis included eight primary studies, derived from populations of European and Asian descent, and did not show a significant difference in TL between 956 PD patients and 1284 controls (p value: 0.246). Our results show that there is no consistent evidence of shorter telomeres in PD patients and suggest the importance of future studies on TL and PD that analyze other populations and also include assessment of TL from different brain regions.
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Affiliation(s)
- Diego A Forero
- Laboratory of Neuropsychiatric Genetics, Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, Bogotá, Colombia.
| | - Yeimy González-Giraldo
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Catalina López-Quintero
- Department of Epidemiology and Biostatistics, College of Human Medicine, Michigan State University, East Lansing, MI, United States
| | - Luis J Castro-Vega
- INSERM, UMR970, Paris-Cardiovascular Research Center, F-75015 Paris, France
| | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia; Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile
| | - George Perry
- College of Sciences, University of Texas at San Antonio, San Antonio, TX, USA
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