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Results 401 - 450 of 1500
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Glotin Anne-Lise - - 2008
The etiology of age-related macular degeneration (AMD), the leading cause of blindness in the developed world, remains poorly understood, but may be related to cumulative oxidative stress. The prime target of the disease is the retinal pigmented epithelium (RPE). To study the molecular mechanisms underlying RPE degeneration, we investigated whether ...
Suzuki Masatoshi - - 2008
Replicative senescence is a fundamental feature in normal human diploid cells and results from dysfunctional telomeres at the Hayflick cell division limit. Ionizing radiation (IR) prematurely induces the same phenotypes as replicative senescence prior to the Hayflick limit. This process is known as stress-induced premature senescence (SIPS). Since the cell ...
Cuenca Francisco - - 2008
A series of tri- and tetra-substituted naphthalene diimides have been designed and synthesized. Several compounds show exceptional affinity for telomeric G-quadruplex DNA in classical and competition FRET assays and SPR studies. They inhibit telomerase in the TRAP assay, and show potent senescence-based short-term anti-proliferative effects on MCF7 and A549 cancer ...
Marie-Egyptienne, Delphine
Telomeres are nucleoprotein structures that protect the ends of chromosomes from recombination and fusion. Telomeres are prefentially maintained by the enzyme telomerase. Telomerase is a reverse transcriptase, minimally composed of two core components, a catalytic subunit, TElomerase Reverse Transcriptase (TERT) and an RNA subunit, Telomerase RNA (TR) that carries the ...
Krunic, Damir
Telomeres are specialized DNA-protein structures at the ends of the linear chromosomes that form protective caps. They are composed of multi-fold double-stranded 5’-TTAGGG-3’ repeats and a 3’ single stranded overhang that loops back and invades the duplex region. The so called T-loop structure is stabilized by a number of associated ...
van Doorn Wouter G - - 2008
This review examines the hypotheses that developmental programmed cell death in leaves is mediated (i) by sugar starvation in the leaf cells or (ii) by sugar accumulation in these cells. Experimental evidence for both hypotheses is critically discussed and found to be lacking. For example, some papers show that sugars ...
Ponsot Elodie - - 2008
Telomere length is an important measure of cell and tissue regenerative capacities. The mean telomere length is classically used as global indicator of a tissue telomere length. In skeletal muscle, which is made of postmitotic myonuclei and satellite cells (muscle stem cells), minimum telomere length is also used to assess ...
Vigetti Davide - - 2008
Human aortic smooth muscle cells (AoSMCs) change their extracellular matrix composition during aging, with direct effects on cellular events and cell migration. For example, active matrix metalloproteinase-2 (MMP-2) is synthesized only by young AoSMCs, whereas aged cells produce only the inactive zymogen form. The pro-MMP-2 activation in young cells depends ...
Nakamura Asako J - - 2008
ABSTRACT: BACKGROUND: Cellular senescence is a state reached by normal mammalian cells after a finite number of cell divisions and is characterized by morphological and physiological changes including terminal cell-cycle arrest. The limits on cell division imposed by senescence may play an important role in both organismal aging and in ...
Makovets Svetlana - - 2008
Telomeres are an unusual component of the genome because they do not encode genes, but their structure and cellular maintenance machinery (which we define as "telotype") are essential for chromosome stability. Cells can switch between different phenotypic states. One such example is when they switch from maintenance mediated by telomerase ...
Huang Jing - - 2008
Sir2, a NAD-dependent deacetylase, modulates lifespan in yeasts, worms and flies. The SIRT1, mammalian homologue of Sir2, regulates signaling for favoring survival in stress. But whether SIRT1 has the function to influence cell viability and senescence under non-stressed conditions in human diploid fibroblasts is far from unknown. Our data showed ...
Mazzucchelli Gabriel D - - 2008
BACKGROUND: Telomerase confers cellular immortality by elongating telomeres, thereby circumventing the Hayflick limit. Extended-life-span cells have been generated by transfection with the human telomerase reverse transcriptase (hTERT) gene. hTERT transfected cell lines may be of outstanding interest to monitor the effect of drugs targeting the telomerase activity. The incidence of ...
Hao Huang - - 2008
The c-Myc and human telomerase reverse transcriptase gene (hTERT) gene are frequently deregulated and overexpressed in malignancy. hTERT activity is induced by c-Myc and strategies designed to inhibit c-Myc expression in cancer cells may have considerable therapeutic value. We designed and used a short hairpin RNA to inhibit c-Myc expression ...
Paeschke Katrin K Institute of Cell Biology, University Witten/Herdecke, Stockumer Strasse 10, Witten, - - 2008
It is well established that telomeres are tethered in the eukaryotic nucleus, but a detailed analysis of the regulation of telomere attachment throughout the cell cycle is still lacking. We show here that the telomeres in the macronucleus of the ciliate Stylonychia lemnae are bound to a sub-nuclear structure by ...
Zhong Ya-Hua - - 2008
A relationship between telomeres and radiosensitivity has been established by several studies based on non-mammalian model systems, mouse models, and few human genetic diseases. However, the relationship has not been proven in human carcinoma cells, which have more clinical significance than these other models. The present study aims to determine ...
Subramanian Lakxmi L Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 S. Ashland Ave., MC669, Chicago, IL 60607, USA. - - 2008
Fission yeast cells survive loss of the telomerase catalytic subunit Trt1 (TERT) through recombination-based telomere maintenance or through chromosome circularization. Although trt1Delta survivors with linear chromosomes can be obtained, they often spontaneously circularize their chromosomes. Therefore, it was difficult to establish genetic requirements for telomerase-independent telomere maintenance. In contrast, when ...
Rózanowski Bartosz - - 2008
The purpose of this study was to determine whether an age-related increase in photoreactivity of human retinal melanosomes (MS) can cause phototoxicity to retinal pigment epithelium (RPE) cells. MS were isolated post mortem from young (20-30 years, young human melanosomes [YHMs]) and old (60-90 years, old human melanosomes [OHMs]) human ...
Churikov Dmitri D Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, PO Box 0524, Cincinnati, Ohio 45267-0524, - - 2008
Removal of the vertebrate telomere protein Pot1 results in a DNA damage response and cell cycle arrest. Here we show that loss of chicken Pot1 causes Chk1 activation, and inhibition of Chk1 signaling prevents the cell cycle arrest. However, arrest still occurs after disruption of ATM, which encodes another DNA ...
Amrite Aniruddha C AC Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska, - - 2008
Age-related macular degeneration (ARMD) is a leading cause of blindness. The major reason for severe vision loss in ARMD is choroidal neovascularization due to an elevation in the expression of angiogenic factors such as vascular endothelial growth factor (VEGF). Drugs with anti-VEGF and antiproliferative activities can be beneficial for the ...
Burton Dominick G A DG School of Pharmacy and Biomolecular Sciences, Cockcroft Building, University of Brighton, Brighton, East Sussex, BN2 4GJ, - - 2007
The senescence of mitotic cells is hypothesized to play a causal role in organismal aging. Cultures of normal human cells become senescent in vitro as a result of a continuous decline in the mitotic fraction from cell turnover. However, one potential barrier to the evaluation of the frequency and distribution ...
Canudas Silvia S Program in Molecular Pathogenesis and Department of Pathology, The Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, NY 10016, - - 2007
Previous studies in human cells indicate that sister telomeres have distinct requirements for their separation at mitosis. In cells depleted for tankyrase 1, a telomeric poly(ADP-ribose) polymerase, sister chromatid arms and centromeres separate normally, but telomeres remain associated and cells arrest in mitosis. Here, we use biochemical and genetic approaches ...
Dmitrieva Natalia I - - 2007
High extracellular NaCl was previously shown to increase the number of DNA breaks in mammalian cells in tissue culture, renal medullary cells in vivo, C. elegans and marine invertebrates. It was also shown to increase reactive oxygen species in renal cells, resulting in oxidation of proteins and DNA. Cellular senescence ...
Shan Hai-Yan - - 2008
Vascular endothelial cells have a finite cell lifespan and eventually enter an irreversible growth arrest, cellular senescence. The functional changes associated with cellular senescence are thought to contribute to human aging and age-related cardiovascular disorders, e.g. atherosclerosis. In this study, induction of Angiotensin II (Ang II) promoted a growth arrest ...
Liu Qian Q Department of Medicine, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, - - 2007
Previous studies have suggested that B cells promote Th2 cell development by inhibiting Th1 cell differentiation. To examine whether B cells are directly required for the development of IL-4-producing T cells in the lymph node during a highly polarized Th2 response, B cell-deficient and wild-type mice were inoculated with the ...
Erenpreisa Jekaterina - - 2007
In the last decade, the concept of "cancer stem cells" has emerged, recognised by the fact that only a small fraction of tumour cells appears to retain the stem cell properties of self-renewal and unlimited proliferation. At the same time, it is well known that cancer is an age-related disease ...
Campisi Judith - - 2007
Cells continually experience stress and damage from exogenous and endogenous sources, and their responses range from complete recovery to cell death. Proliferating cells can initiate an additional response by adopting a state of permanent cell-cycle arrest that is termed cellular senescence. Understanding the causes and consequences of cellular senescence has ...
Bollmann F Mathias - - 2007
Cells lacking aerobic metabolism because of damaged mtDNA accumulate in many postmitotic tissues in the course aging. Although being only a small fraction of cells, they might play a major role in oxidative stress affecting the whole body. However, it remains unclear how such cells, which are under normal circumstances ...
Baerlocher Gabriela M - - 2007
OBJECTIVE: To study if telomere length can be used as a surrogate marker for the mitotic history in normal and affected hematopoietic cells from patients with paroxysmal nocturnal hemoglobinuria (PNH). METHODS: The telomere length was measured by automated multicolor flow fluorescence in situ hybridization in glycosyl-phosphatidyl-inositol anchored protein (GPI)-negative and ...
Baird Duncan M - - 2008
Human telomeres are intrinsically dynamic structures, with multiple biological processes operating to generate substantial length heterogeneity. Processes that operate specifically at the terminus, that include the end-replication problem coupled with C-strand resection, result in gradual telomere erosion with ongoing cell division. Rates of telomere erosion can be modulated by cell ...
Zhao Chang-Qing - - 2007
Intervertebral disc degeneration, which mimics disc aging but occurs at an accelerated rate, is considered to be related to neck or low back pain and disc herniation. Degenerated discs show breakdown of the extracellular matrix and thus fail to bear the daily loadings exerted on the spine. Rather than a ...
Seluanov Andrei A Department of Biology, University of Rochester, Rochester, NY 14627-0211, United - - 2007
Aging is associated with accumulation of genomic rearrangements consistent with aberrant repair of DNA breaks. We have shown previously that DNA repair by non-homologous end joining (NHEJ) becomes less efficient and more error-prone in senescent cells. Here, we show that the levels of Ku70 and Ku80 drop approximately twofold in ...
Vernace Vita A - - 2007
In all cells, protein degradation is a constant, ongoing process that is critical for cell survival and repair. The ubiquitin/proteasome pathway (UPP) is the major proteolytic pathway that degrades intracellular proteins in a regulated manner. It plays critical roles in many cellular processes and diseases. Disruption of the UPP is ...
Davison Glenda Mary - - 2007
Telomeres are DNA structures which serve to stabilize chromosomes. In human cells telomeres progressively shorten with each cell division leading to eventual chromosome instability and cell death. Telomerase is a DNA polymerase which is required for the maintenance of telomeres. Therefore, telomeres and telomerase play a role in the regulation ...
Matulić M - - 2007
Telomeres are among the most important structures in eukaryotic cells. Creating the physical ends of linear chromosomes, they play a crucial role in maintaining genome stability, control of cell division, cell growth and senescence. In vertebrates, telomeres consist of G-rich repetitive DNA sequences (TTAGGG)n and specific proteins, creating a specialized ...
Yan Haifang - - 2007
Senescence or cell death in plant leaves is known to be inducible by darkness or H(2)O(2). When the Arabidopsis gene MAX2/ORE9 is disrupted, leaf senescence or cell death in response to the above stimuli is delayed. Because the rice (Oryza sativa L.) gene DWARF3 (D3) is orthologous to MAX2/ORE9, we ...
Sprung Carl N - - 2007
PURPOSE: To investigate the link between radiosensitivity and telomere length in murine lymphoid cell line stocks that have similar genetic backgrounds but different radiosensitivities. MATERIALS AND METHODS: We used two stocks from both the parental L5,178Y-R cell line and the repair-deficient radiosensitive subline, L5,178Y-S, to assess telomere length. We used ...
Liao Chien-Huang - - 2007
Recombinant fungal immunomodulatory protein, reFIP-gts, was cloned from Ganoderma tsugae and purified. In our previous study, it was shown that reFIP-gts has anti-telomerase effects in A549 cells. Here, we proved that reFIP-gts entry into the cell and localization in endoplasmic reticulum can result in ER stress, thereby increasing ER stress ...
Park Chaehwa - - 2007
Recently, negative effects of phosphatase in tumorigenesis and metastasis have been suggested in various tumor types. In this study, we showed that RhoA activation modulated phosphatase during senescence-like arrest in human prostate cancer cells. Under senescence-inducing condition, decreased Erk phosphorylation was detected in caRhoA-transfected cells and inactivation of Erk, but ...
Pollok S - - 2007
Cell division cycle protein 45 (Cdc45) plays a critical role in DNA replication to ensure that chromosomal DNA is replicated only once per cell cycle. We analysed the expression of human Cdc45 in proliferating and nonproliferating cells. Our findings show that Cdc45 protein is absent from long-term quiescent, terminally differentiated ...
Jennings Paul - - 2007
The nephrotoxic potential of the widely used immunosuppressive agent cyclosporine A (CsA) is well recognized. However, the mechanism of renal tubular toxicity is not yet fully elucidated. Chronic CsA nephropathy and renal organ aging share some clinical features, such as renal fibrosis and tubular atrophy, raising the possibility that CsA ...
Khaw Aik Kia - - 2007
The aim of the present study is to investigate the effect of histone deacetylase inhibitor, trichostatin A (TSA) on the cell growth, apoptosis, genomic DNA damage and the expression of telomerase and associated factors in human normal and brain cancer cells. Here, human normal un-transformed fibroblasts (MRC-5), human normal hTERT-immortalised ...
Aida Junko - - 2007
We developed a novel method for evaluating telomere length in 6 cell types of noncancerous and cancerous mucosal tissues from 11 cases of gastric neoplasm using the quantitative fluorescence in situ hybridization method with telomere and centromere peptide nucleic acid probes. Our telomere length estimates were determined from the background-corrected ...
Sima Ni - - 2007
OBJECTIVE: Human papillomavirus type 16 (HPV-16) is a high-risk DNA tumor virus involved in the development of cervical carcinomas. Substantial studies have demonstrated that E6 and E7 oncoproteins of HPV-16 could induce cell proliferation and immortalization. Repression of E6 and/or E7 oncogenes may induce cervical cancer cells to undergo apoptosis ...
Côté Marceline M Department of Microbiology and Immunology, McGill University, Montreal, - - 2007
The RON receptor tyrosine kinase is a member of the MET proto-oncogene family and is important for cell proliferation, differentiation, and cancer development. Here, we created a series of Madin-Darby canine kidney (MDCK) epithelial cell clones that express different levels of RON, and have investigated their biological properties. While low ...
Stöckl Petra - - 2007
The mitochondrial theory of aging predicts that functional alterations in mitochondria leading to reactive oxygen species (ROS) production contribute to the aging process in most if not all species. Using cellular senescence as a model for human aging, we have recently reported partial uncoupling of the respiratory chain in senescent ...
Antal T T Center for Polymer Studies and Department of Physics, Boston University, Boston, MA 02215, - - 2007
We investigate a model of cell division in which the length of telomeres within a cell regulates its proliferative potential. At each division, telomeres undergo a systematic length decrease as well as a superimposed fluctuation due to exchange of telomere DNA between the two daughter cells. A cell becomes senescent ...
Ferrara Luciana L Department of Biological Sciences, University of Delaware, Delaware Biotechnology Institute, 15 Innovation Way, Newark, DE 19711, - - 2007
We have previously shown that activation of the homologous recombinational repair pathway leads to a block of cell division in corrected cells, possibly through the activity of checkpoint proteins Chk1 and Chk2. In this study, we examine the long-term impact of this stalling on the growth of cells that have ...
Moreau Marielle - - 2007
BACKGROUND AND OBJECTIVES: Cell longevity is linked to sirtuins (silent information regulators), which belong to a family of enzymes implicated in gene silencing, apoptosis, fatty acid metabolism, and regulation of cellular life spans of organisms. Sirtuins are associated with genes that coordinate and optimize the functions of cells as cells ...
Vega Leticia R - - 2007
The Saccharomyces cerevisiae Pif1p helicase is a negative regulator of telomere length that acts by removing telomerase from chromosome ends. The catalytic subunit of yeast telomerase, Est2p, is telomere associated throughout most of the cell cycle, with peaks of association in both G1 phase (when telomerase is not active) and ...
Garbe James C - - 2007
Cultured human mammary epithelial cells (HMEC) encounter two distinct barriers to indefinite growth. The first barrier, originally termed selection, can be overcome through loss of expression of the cyclin-dependent kinase inhibitor p16(INK4A). The resultant p16-, p53+ post-selection HMEC encounter a second barrier, termed agonescence, associated with critically shortened telomeres and ...
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