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Ram P Naikawadi, Supparerk Disayabutr, Benat Mallavia, Matthew L Donne, Gary Green, Janet L La, Jason R Rock, Mark R Looney, Paul J Wolters
Telomeres are short in type II alveolar epithelial cells (AECs) of patients with idiopathic pulmonary fibrosis (IPF). Whether dysfunctional telomeres contribute directly to development of lung fibrosis remains unknown. The objective of this study was to investigate whether telomere dysfunction in type II AECs, mediated by deletion of the telomere shelterin protein TRF1, leads to pulmonary fibrosis in mice (SPC-Cre TRF1(fl/fl) mice). Deletion of TRF1 in type II AECs for 2 weeks increased γH2AX DNA damage foci, but not histopathologic changes in the lung...
September 8, 2016: JCI Insight
Tania Aguado, Francisco J Gutiérrez, Esther Aix, Ralph P Schneider, Giovanna Giovinnazo, María A Blasco, Ignacio Flores
Induced pluripotent stem cells (iPSCs) can be differentiated in vitro and in vivo to all cardiovascular lineages and are therefore a promising cell source for cardiac regenerative therapy. However, iPSC lines do not all differentiate into cardiomyocytes with the same efficiency. Here, we show that telomerase-competent iPSCs with relatively long telomeres and high expression of the shelterin-complex protein TRF1 (iPSC(highT) ) differentiate sooner and more efficiently into cardiomyocytes than those with relatively short telomeres and low TRF1 expression (iPSC(lowT) )...
September 10, 2016: Stem Cells
Jasminka Boskovic, Jaime Martinez-Gago, Marinela Mendez-Pertuz, Alberto Buscato, Jorge Luis Martinez-Torrecuadrada, Maria A Blasco
Telomeres are specific DNA-protein structures found at both ends of eukaryotic chromosomes that protect the genome from degradation and from being recognized as double-stranded breaks. In vertebrates, telomeres are composed of tandem repeats of the TTAGGG sequence that are bound by a six-subunit complex called shelterin. Molecular mechanisms of telomere functions remain unknown in large part due to lack of structural data on shelterins, shelterin complex, and its interaction with the telomeric DNA repeats. TRF1 is one of the best studied shelterin components however the molecular architecture of the full length protein remains unknown...
August 25, 2016: Journal of Biological Chemistry
Hai-Long Li, Jun Song, Hong-Mei Yong, Ping-Fu Hou, Yan-Su Chen, Wen-Bo Song, Jin Bai, Jun-Nian Zheng
PIN2/TRF1-interacting telomerase inhibitor 1 (PinX1) is a novel cloned gene located at human chromosome 8p23, playing a vital role in maintaining telomeres length and chromosome stability. It has been demonstrated to be involved in tumor genesis and progression in most malignancies. However, some researches showed opposing molecular status of PinX1 gene and its expression patterns in several other types of tumors. The pathogenic mechanism of PinX1 expression in human malignancy is not yet clear. Moreover, emerging evidence suggest that PinX1 (especially its TID domain) might be a potential new target cancer treatment...
August 19, 2016: Oncotarget
Ilgen Mender, Jerry W Shay
Telomerase maintains telomeric DNA in eukaryotes during early developments, ~90% of cancer cells and some proliferative stem like cells. Telomeric repeats at the end of chromosomes are associated with the shelterin complex. This complex consists of TRF1, TRF2, Rap1, TIN2, TPP1, POT1 which protect DNA from being recognized as DNA double-stranded breaks. Critically short telomeres or impaired shelterin proteins can cause telomere dysfunction, which eventually induces DNA damage responses at the telomeres. DNA damage responses can be identified by antibodies to 53BP1, gammaH2AX, Rad17, ATM, and Mre11...
November 20, 2015: Bio-protocol
Lihua Yao, Xiaolan Guo
As an important telomere binding protein, TPP1 protects the ends of telomeres and maintains the stability and integrity of its structure and function by interacting with other five essential core proteins (POT1, TRF1, TRF2, TIN2, and RAP1) to form a complex called Shelterin. Recently, researchers have discovered that TPP1 participates in protection of telomeres and regulation of telomerase activity. The relationship between TPP1 and tumorigenesis, tumor progression and treatment has also been investigated. This paper reviews the latest findings of TPP1 regarding to its structure, function and interaction with other proteins involved in tumorigenesis...
August 2016: Zhonghua Yi Xue Yi Chuan Xue za Zhi, Zhonghua Yixue Yichuanxue Zazhi, Chinese Journal of Medical Genetics
Umesh Kalathiya, Monikaben Padariya, Maciej Baginski
Shelterin is a six-protein complex (TRF1, TRF2, POT1, RAP1, TIN2, and TPP1) that also functions in smaller subsets in regulation and protection of human telomeres. Two closely related proteins, TRF1 and TRF2, make high-affinity contact directly with double-stranded telomeric DNA and serve as a molecular platform. Protein TIN2 binds to TRF1 and TRF2 dimer-forming domains, whereas Apollo makes interaction only with TRF2. To elucidate the molecular basis of these interactions, we employed molecular dynamics (MD) simulations of TRF1TRFH-TIN2TBM and TRF2TRFH-TIN2TBM/ApolloTBM complexes and of the isolated proteins...
July 22, 2016: European Biophysics Journal: EBJ
Heather Root, Andrew Larsen, Martin Komosa, Fakhriya Al'Azri, Ren Li, David P Bazett-Jones, M Stephen Meyn
Fanconi Anemia and Bloom syndrome are genomic instability syndromes caused by mutations in proteins that participate in overlapping DNA repair and replication pathways. Here, we show that the monoubiquitinated form of the Fanconi Anemia protein FANCD2 acts in opposition to the BLM DNA helicase to restrain telomere replication and recombination in human cells that utilize the Alternative Lengthening of Telomeres (ALT) pathway. ALT relies on exchanges of telomeric DNA to maintain telomeres, a process that we show FANCD2 suppresses...
July 17, 2016: Human Molecular Genetics
Vijaya Lakshmi Tiruveedi, Swarna Bale, Amit Khurana, Chandraiah Godugu
Tankyrases belong to a group of enzymes called poly ADP ribosyl polymerases (PARPs). With the advent of a new class of small molecule inhibitors of PARP for clinical use like OLAPARIB; that gained accelerated approval by the USFDA in treating ovarian and breast cancers, the horizons of the PARPs as a novel target in various disease conditions has risen. Tankyrases (PARP 5) are yet another class of PARPs that perform poly ADP ribosylation on different substrate proteins aiding in progression of many diseases like cancer, fibrosis, diabetes and neurological disorders even...
July 15, 2016: Current Drug Targets
Samrat Roy Choudhury, Yi Cui, Anoop Narayanan, David P Gilley, Nazmul Huda, Chiao-Ling Lo, Feng C Zhou, Dinesh Yernool, Joseph Irudayaraj
Telomere length homeostasis, critical for chromosomal integrity and genome stability, is controlled by intricate molecular regulatory machinery that includes epigenetic modifications. Here, we examine site-specific and spatiotemporal alteration of the subtelomeric methylation of CpG islands using optogenetic tools to understand the epigenetic regulatory mechanisms of telomere length maintenance. Human DNA methyltransferase3A (DNMT3A) were assembled selectively at chromosome ends by fusion to cryptochrome 2 protein (CRY2) and its interacting complement, the basic helix loop helix protein-1 (CIB1)...
July 4, 2016: Oncotarget
Jiahui An, Mengying Wu, Xiaoru Xin, Zhuojia Lin, Xiaonan Li, Qidi Zheng, Xin Gui, Tianming Li, Hu Pu, Haiyan Li, Dongdong Lu
Cancer stem cells are associated with tumor recurrence. IKK is a protein kinase that is composed of IKKα, IKKβ, IKKγ. Herein, we demonstrate that IKKα plus IKKβ promoted and IKKγ inhibited liver cancer stem cell growth in vitro and in vivo. Mechanistically, IKKα plus IKKβ enhanced and IKKγ inhibited the interplay among HP1α, HP1β and HP1γ that competes for the interaction among HP1α, SUZ12, HEZ2. Therefore, IKKα plus IKKβ inhibited and IKKγ enhanced the activity of H3K27 methyltransferase SUZ12 and EZH2, which methylates H3K27 immediately sites on HOTAIR promoter region...
June 29, 2016: Oncotarget
Yinshan Bai, Meiying Feng, Shanshan Liu, Hengxi Wei, Li Li, Xianwei Zhang, Chao Shen, Shouquan Zhang, Ningfang Ma
Mouse spermatogonial stem cells (mSSCs) may be reprogrammed to become pluripotent stem cells under in vitro culture conditions, due to epigenetic modifications, which are closely associated with the expression of transcription factors and epigenetic factors. Thus, this study was conducted to compare the gene expression of transcription factors and epigenetic factors in mSSCs and mouse embryonic stem cells (mESCs). Firstly, the freshly isolated mSSCs [mSSCs (f)] were enriched by magnetic-activated cell sorting with Thy1...
August 2016: International Journal of Molecular Medicine
Amel Chebel, Régine Catallo, Céline Mabon, Emmanuel Bachy, Thomas Wenner, Gilles Salles, Claire Pouteil-Noble, Martine Ffrench
Several studies reported the benefits of switching from anticalcineurins to mTOR inhibitors to avoid cancer occurrence after organ transplantation. The purpose of our study was to determine in vivo biological markers to explain these benefits. Cellular changes related to cellular senescence and DNA damage were analyzed in peripheral blood lymphocytes. Thirty-five kidney transplanted patients receiving anticalcineurins were investigated: 17 patients were proposed to switch to rapamycin and 18 patients with similar age and transplantation duration, continued anticalcineurins...
September 2016: European Journal of Cell Biology
Sophie Zaaijer, Nadeem Shaikh, Rishi Kumar Nageshan, Julia Promisel Cooper
Clearance of entangled DNA from the anaphase mid-region must accurately proceed in order for chromosomes to segregate with high fidelity. Loss of Taz1 (fission yeast ortholog of human TRF1/TRF2) leads to stalled telomeric replication forks that trigger telomeric entanglements; the resolution of these entanglements fails at ≤20°C. Here, we investigate these entanglements and their promotion by the conserved replication/repair protein Rif1. Rif1 plays no role in taz1Δ fork stalling. Rather, Rif1 localizes to the anaphase mid-region and regulates the resolution of persisting DNA structures...
June 28, 2016: Cell Reports
Jiangguo Lin, Preston Countryman, Haijiang Chen, Hai Pan, Yanlin Fan, Yunyun Jiang, Parminder Kaur, Wang Miao, Gisele Gurgel, Changjiang You, Jacob Piehler, Neil M Kad, Robert Riehn, Patricia L Opresko, Susan Smith, Yizhi Jane Tao, Hong Wang
Proper chromosome alignment and segregation during mitosis depend on cohesion between sister chromatids. Cohesion is thought to occur through the entrapment of DNA within the tripartite ring (Smc1, Smc3 and Rad21) with enforcement from a fourth subunit (SA1/SA2). Surprisingly, cohesin rings do not play a major role in sister telomere cohesion. Instead, this role is replaced by SA1 and telomere binding proteins (TRF1 and TIN2). Neither the DNA binding property of SA1 nor this unique telomere cohesion mechanism is understood...
July 27, 2016: Nucleic Acids Research
Huazong Yin, Liuwang Nie, Feifei Zhao, Huaxing Zhou, Haifeng Li, Xianmei Dong, Huanhuan Zhang, Yuqin Wang, Qiong Shi, Jun Li
Mauremys reevesii (Geoemydidae) is one of the most common and widespread semi-aquatic turtles in East Asia. The unusually long lifespan of some individuals makes this turtle species a potentially useful model organism for studying the molecular basis of longevity. In this study, pooled total RNA extracted from liver, spleen and skeletal-muscle of three adult individuals were sequenced using Illumina Hiseq 2500 platform. A set of telomere-related genes were found in the transcriptome, including tert, tep1, and six shelterin complex proteins coding genes (trf1, trf2, tpp1, pot1, tin2 and rap1)...
2016: PeerJ
Cory Rice, Emmanuel Skordalakes
Telomeres comprise the ends of eukaryotic chromosomes and are essential for cell proliferation and genome maintenance. Telomeres are replicated by telomerase, a ribonucleoprotein (RNP) reverse transcriptase, and are maintained primarily by nucleoprotein complexes such as shelterin (TRF1, TRF2, TIN2, RAP1, POT1, TPP1) and CST (Cdc13/Ctc1, Stn1, Ten1). The focus of this review is on the CST complex and its role in telomere maintenance. Although initially thought to be unique to yeast, it is now evident that the CST complex is present in a diverse range of organisms where it contributes to genome maintenance...
2016: Computational and Structural Biotechnology Journal
Larissa Alexsandra da Silva Neto Trajano, Ana Carolina Stumbo, Camila Luna da Silva, Andre Luiz Mencalha, Adenilson S Fonseca
Infrared laser therapy is used for skeletal muscle repair based on its biostimulative effect on satellite cells. However, shortening of telomere length limits regenerative potential in satellite cells, which occurs after each cell division cycle. Also, laser therapy could be more effective on non-physiologic tissues. This study evaluated low-level infrared laser exposure effects on mRNA expression from muscle injury repair and telomere stabilization genes in myoblasts in normal and stressful conditions. Laser fluences were those used in clinical protocols...
August 2016: Lasers in Medical Science
Yuanlong Ge, Shu Wu, Yong Xue, Jun Tao, Feng Li, Yanlian Chen, Haiying Liu, Wenbin Ma, Junjiu Huang, Yong Zhao
The majority of tumor cells overcome proliferative limit by expressing telomerase. Whether or not telomerase preferentially extends the shortest telomeres is still under debate. When human cancer cells are cultured at neutral pH, telomerase extends telomeres in telomere length-independent manner. However, the microenvironment of tumor is slightly acidic, and it is not yet known how this influences telomerase action. Here, we examine telomere length homeostasis in tumor cells cultured at pHe 6.8. The results indicate that telomerase preferentially extends short telomeres, such that telomere length distribution narrows and telomeres become nearly uniform in size...
September 30, 2016: Nucleic Acids Research
Florence R Wilson, Angus Ho, John R Walker, Xu-Dong Zhu
TRF1, a duplex telomeric DNA binding protein, is implicated in homologous-recombination-based alternative lengthening of telomeres, known as ALT. However, how TRF1 promotes ALT activity has yet to be fully characterized. Here we report that Cdk-dependent TRF1 phosphorylation on T371 acts as a switch to create a pool of TRF1, referred to as (pT371)TRF1, which is recruited to ALT-associated PML bodies (APBs) in S and G2 phases independently of its binding to telomeric DNA. We find that phosphorylation of T371 is essential for APB formation and C-circle production, both of which are hallmarks of ALT...
July 1, 2016: Journal of Cell Science
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