Armadillo repeat-containing proteins (ARMCs) are a large family found throughout eukaryotes, which play prominent roles in cell adhesion, signaling and cytoskeletal regulation. The ARMC6 protein is highly conserved in primates, including humans, but to date does not have a clear function beyond initial hints of a link to cancer and telomerase activity. We report here in vitro experiments showing ARMC6 binding to DNA promoter sequences from several cancer-related genes (e.g., EGFR, VEGF and c-MYC), and also to the telomeric RNA repeat (TERRA). ARMC6 binding activity appears to recognize G-quadruplex motifs, which are being increasingly implicated as structure-based protein binding sites in chromosome maintenance and repair. In vivo investigation of ARMC6 function revealed that when this protein is overexpressed in human cell lines, there is different expression of genes connected with oncogenic pathways and those implicated in downstream non-canonical telomerase pathways (e.g., VEGF, hTERT, c-MYC, ESM1, MMP3). ARMC6 is already known to interact with human shelterin protein TRF2 and telomerase. The protein binds G-quadruplex structures and does so preferentially to RNA over DNA. As such, this protein may be an example of how a non-canonical nucleic acid structural motif allows mediation between gene regulation and telomeric chromatin rearrangement pathways.
- MeSH
- DNA vazebné proteiny MeSH
- G-kvadruplexy * MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- nádory genetika metabolismus MeSH
- promotorové oblasti (genetika) * MeSH
- proteiny s doménou armadillo * metabolismus genetika MeSH
- regulace genové exprese u nádorů MeSH
- RNA metabolismus genetika MeSH
- telomerasa metabolismus genetika MeSH
- telomery * metabolismus MeSH
- transkripční faktory MeSH
- vazba proteinů MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Genetic and epigenetic alterations of the telomere maintenance machinery like telomere length and telomerase reverse transcriptase (encoded by TERT gene) are reported in several human malignancies. However, there is limited knowledge on the status of the telomere machinery in periampullary carcinomas (PAC) which are rare and heterogeneous groups of cancers arising from different anatomic sites around the ampulla of Vater. In the current study, we investigated the relative telomere length (RTL) and the most frequent genetic and epigenetic alterations in the TERT promoter in PAC and compared it with tumor-adjacent nonpathological duodenum (NDu). We found shorter RTLs (1.27 vs 1.33, P = 0.01) and lower TERT protein expression (p = 0.04) in PAC tissues as compared to the NDu. Although we did not find any mutation at two reactivating hotspot mutation sites of the TERT promoter, we detected polymorphism in 45% (9/20) of the cases at rs2853669 (T > C). Also, we found a hypermethylated region in the TERT promoter of PACs consisting of four CpGs (cg10896616 with Δβ 7%; cg02545192 with Δβ 9%; cg03323598 with Δβ 19%; and cg07285213 with Δβ 15%). In conclusion, we identified shorter telomeres with DNA hypermethylation in the TERT promoter region and lower TERT protein expression in PAC tissues. These results could be used further to investigate molecular pathology and develop theranostics for PAC.
In contrast to the catalytic subunit of telomerase, its RNA subunit (TR) is highly divergent in size, sequence and biogenesis pathways across eukaryotes. Current views on TR evolution assume a common origin of TRs transcribed with RNA polymerase II in Opisthokonta (the supergroup including Animalia and Fungi) and Trypanosomida on one hand, and TRs transcribed with RNA polymerase III under the control of type 3 promoter, found in TSAR and Archaeplastida supergroups (including e.g. ciliates and Viridiplantae taxa, respectively). Here, we focus on unknown TRs in one of the largest Animalia order - Hymenoptera (Arthropoda) with more than 300 available representative genomes. Using a combination of bioinformatic and experimental approaches, we identify their TRs. In contrast to the presumed type of TRs (H/ACA box snoRNAs transcribed with RNA Polymerase II) corresponding to their phylogenetic position, we find here short TRs of the snRNA type, likely transcribed with RNA polymerase III under the control of the type 3 promoter. The newly described insect TRs thus question the hitherto assumed monophyletic origin of TRs across Animalia and point to an evolutionary switch in TR type and biogenesis that was associated with the divergence of Arthropods.
- MeSH
- Eukaryota genetika MeSH
- fylogeneze MeSH
- Hymenoptera * genetika MeSH
- konformace nukleové kyseliny MeSH
- RNA-polymerasa II genetika metabolismus MeSH
- RNA-polymerasa III genetika metabolismus MeSH
- RNA genetika MeSH
- rostliny genetika MeSH
- telomerasa * genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
About 30 percent of patients diagnosed with myelodysplastic syndromes (MDS) progress to acute myeloid leukemia (AML). The senescence of bone marrow?derived mesenchymal stem cells (BMSCs) seems to be one of the determining factors in inducing this drift. Research is continuously looking for new methodologies and technologies that can use bioelectric signals to act on senescence and cell differentiation towards the phenotype of interest. The Radio Electric Asymmetric Conveyer (REAC) technology, aimed at reorganizing the endogenous bioelectric activity, has already shown to be able to determine direct cell reprogramming effects and counteract the senescence mechanisms in stem cells. Aim of the present study was to prove if the anti-senescence results previously obtained in different kind of stem cells with the REAC Tissue optimization - regenerative (TO-RGN) treatment, could also be observed in BMSCs, evaluating cell viability, telomerase activity, p19ARF, P21, P53, and hTERT gene expression. The results show that the REAC TO-RGN treatment may be a useful tool to counteract the BMSCs senescence which can be the basis of AML drift. Nevertheless, further clinical studies on humans are needed to confirm this hypothesis.
Telomere biology is closely linked to the process of aging. The restoration of telomere length by maintaining telome-rase activity in certain cell types of human adults allows for the proliferative capacity of the cells and preserves the regeneration potential of the tissue. The absence of telome-rase, that leads to telomere attrition and irreversible cell cycle arrest in most somatic cells, acts as a protective mechanism against uncontrolled cancer growth. Nevertheless, there have been numerous studies indicating noncanonical functions of telomerase besides those involved in telomere lengthening. Eusocial insects serve as a great system for aging research. This is because eusocial reproductives, such as queens and kings, have a significantly extended lifespan compared to nonreproductive individuals of the same species. We report that the somatic tissues of honeybee queens (Apis mellifera) are associated with upregulated telomerase activity; however, this upregulation does not fully correlate with the rate of DNA replication in the tissues. This indicates a noncanonical role of telomerase in the somatic tissues of honeybee queens.
Telomere shortening at chromosomal ends due to the constraints of the DNA replication process acts as a tumor suppressor by restricting the replicative potential in primary cells. Cancers evade that limitation primarily through the reactivation of telomerase via different mechanisms. Mutations within the promoter of the telomerase reverse transcriptase (TERT) gene represent a definite mechanism for the ribonucleic enzyme regeneration predominantly in cancers that arise from tissues with low rates of self-renewal. The promoter mutations cause a moderate increase in TERT transcription and consequent telomerase upregulation to the levels sufficient to delay replicative senescence but not prevent bulk telomere shortening and genomic instability. Since the discovery, a staggering number of studies have resolved the discrete aspects, effects and clinical relevance of the TERT promoter mutations. The promoter mutations link transcription of TERT with oncogenic pathways, associate with markers of poor outcome and define patients with reduced survivals in several cancers. In this review, we discuss the occurrence and impact of the promoter mutations and highlight the mechanism of TERT activation. We further deliberate on the foundational question of the abundance of the TERT promoter mutations and a general dearth of functional mutations within noncoding sequences, as evident from pan-cancer analysis of the whole-genomes. We posit that the favorable genomic constellation within the TERT promoter may be less than a common occurrence in other noncoding functional elements. Besides, the evolutionary constraints limit the functional fraction within the human genome, hence the lack of abundant mutations outside the coding sequences.
- MeSH
- aktivace transkripce MeSH
- lidé MeSH
- mutace * MeSH
- nádory klasifikace genetika patologie MeSH
- nestabilita genomu MeSH
- promotorové oblasti (genetika) * MeSH
- stárnutí buněk MeSH
- telomerasa genetika metabolismus MeSH
- telomery genetika MeSH
- zkracování telomer MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Current multiagent chemotherapy regimens have improved the cure rate in acute leukemia patients, but they are highly toxic and poorly efficient in relapsed patients. To improve the treatment approaches, new specific molecules are needed. The G-quadruplexes (G4s), which are noncanonical nucleic acid structures found in specific guanine-rich DNA or RNA, are involved in many cellular events, including control of gene expression. G4s are considered as targets for the development of anticancer agents. Heterocyclic molecules are well known to target and stabilize G4 structures. Thus, a new series of 2,9-bis[(substituted-aminomethyl)phenyl]-1,10-phenanthroline derivatives (1a-i) was designed, synthesized, and evaluated against five human myeloid leukemia cell lines (K562, KU812, MV4-11, HL60, and U937). Their ability to stabilize various oncogene promoter G4 structures (c-MYC, BCL-2, and K-RAS) as well as the telomeric G4 was also determined through the fluorescence resonance energy transfer melting assay and native mass spectrometry. In addition, the more bioactive ligands 1g-i were tested for telomerase activity in HuT78 and MV4-11 protein extracts.
- MeSH
- akutní myeloidní leukemie farmakoterapie patologie MeSH
- antitumorózní látky chemická syntéza chemie farmakologie MeSH
- buňky K562 MeSH
- fenantroliny chemická syntéza chemie farmakologie MeSH
- G-kvadruplexy účinky léků MeSH
- HL-60 buňky MeSH
- lidé MeSH
- ligandy MeSH
- nádorové buněčné linie MeSH
- racionální návrh léčiv MeSH
- rezonanční přenos fluorescenční energie MeSH
- telomerasa metabolismus MeSH
- U937 buňky MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Telomeres are repetitive nucleoprotein DNA sequences that shorten with each cell division. The stem cells activate telomerase to compensate for the telomere loss. This study aimed to evaluate the effect of cultivation passaging on the relative telomere length and proliferation capacity of dental pulp stem cells. We used ten dental pulp stem cell (DPSC) lineages stored for 12 months using uncontrolled-rate freezing to reach the study's goal. We analyzed their proliferation rate, phenotype using flow cytometry, multipotency, and relative telomere length using a qPCR analysis. We determined the relative telomere length in the added study by performing analysis after one, two, and three weeks of cultivation with no passaging. We documented the telomere attrition with increasing passaging. The shorter the relative telomere length, the lower reached population doublings, and longer population doubling time were observed at the end of the cultivation. We observed the telomere prolongation in DPSCs cultivated for two weeks with no passaging in the added subsequent study. We concluded that excessive proliferation demands on DPSCs during in vitro cultivation result in telomere attrition. We opened the theory that the telomerase might be more efficient during cell cultivation with no passaging. This observation could help in preserving the telomere length during ex vivo DPSC expansion.
- MeSH
- fenotyp MeSH
- imunohistochemie MeSH
- kmenové buňky cytologie metabolismus MeSH
- lidé MeSH
- polymerázová řetězová reakce MeSH
- proliferace buněk genetika fyziologie MeSH
- průtoková cytometrie MeSH
- telomerasa metabolismus MeSH
- telomery genetika MeSH
- zubní dřeň cytologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The gene coding for the telomerase reverse transcriptase (TERT) is essential for the maintenance of telomeres. Previously we described the presence of three TERT paralogs in the allotetraploid plant Nicotiana tabacum, while a single TERT copy was identified in the paleopolyploid model plant Arabidopsis thaliana. Here we examine the presence, origin and functional status of TERT variants in allotetraploid Nicotiana species of diverse evolutionary ages and their parental genome donors, as well as in other diploid and polyploid plant species. A combination of experimental and in silico bottom-up analyses of TERT gene copies in Nicotiana polyploids revealed various patterns of retention or loss of parental TERT variants and divergence in their functions. RT-qPCR results confirmed the expression of all the identified TERT variants. In representative plant and green algal genomes, our synteny analyses show that their TERT genes were located in a conserved locus that became advantageous after the divergence of eudicots, and the gene was later translocated in several plant groups. In various diploid and polyploid species, translocation of TERT became fixed in target loci that show ancient synapomorphy.
Colorectal cancer (CRC) continues to be one of the leading malignancies and causes of tumour-related deaths worldwide. Both impaired DNA repair mechanisms and disrupted telomere length homeostasis represent key culprits in CRC initiation, progression and prognosis. Mechanistically, altered DNA repair results in the accumulation of mutations in the genome and, ultimately, in genomic instability. DNA repair also determines the response to chemotherapeutics in CRC treatment, suggesting its utilisation in the prediction of therapy response and individual approach to patients. Telomere attrition resulting in replicative senescence, simultaneously by-passing cell cycle checkpoints, is a hallmark of malignant transformation of the cell. Telomerase is almost ubiquitous in advanced solid cancers, including CRC, and its expression is fundamental to cell immortalisation. Therefore, there is a persistent effort to develop therapeutics, which are telomerase-specific and gentle to non-malignant tissues. However, in practice, we are still at the level of clinical trials. The current state of knowledge and the route, which the research takes, gives us a positive perspective that the problem of molecular models of telomerase activation and telomere length stabilisation will finally be solved. We summarise the current literature herein, by pointing out the crosstalk between proteins involved in DNA repair and telomere length homeostasis in relation to CRC.
- MeSH
- chromozomální nestabilita MeSH
- homeostáza telomer genetika MeSH
- kolorektální nádory farmakoterapie genetika metabolismus patologie MeSH
- kontrolní body buněčného cyklu genetika MeSH
- lidé MeSH
- nádorová transformace buněk genetika metabolismus MeSH
- oprava DNA genetika MeSH
- stárnutí buněk genetika MeSH
- telomerasa genetika metabolismus MeSH
- telomery metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
