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Topic: Telomerase

Related Topics

Programmed cell death

DNA damage

Biological immortality

Gene therapy

Apoptosis

Telomere

Germ cell

Reverse transcriptase

Messenger RNA

Life extension

Leonard Hayflick

RNA polymerase

Senescence

Cancer

Protein

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	Telomerase - Wikipedia, the free encyclopedia
		Telomerase is an enzyme, that adds specific DNA sequence repeats, ("TTAGGG" in all vertebrates) to the 3' ("three prime") end of DNA strands, in the telomere regions at the ends of chromosomes which contain condensed DNA material during replication.
		Telomerase activation has been observed in ~90% of all human tumors, suggesting that the immortality conferred by telomerase is required for cancer development.
		Mutations in TERT, the gene for telomerase reverse transcriptase, in aplastic anemia.
	en.wikipedia.org /wiki/Telomerase (1463 words)

	Telomeres and Telomerase: The Cellular Timekeepers (Site not responding. Last check: 2007-10-07)
		Telomerase is a reverse-transcriptase enzyme that elongates the telomeres and thus corrects the normal telomere erosion (Greider and Blackburn, 1985).
		Telomerase activity is higher in primitive progenitor cells and then downregulated during proliferation and differentiation (Chiu et al., 1996).
		It is caused by a mutation in the DKC1 gene.
	www.senescence.info /telomeres.html (3994 words)

	Telomerase enzyme and leukemia - The Doctors Lounge(TM) (Site not responding. Last check: 2007-10-07)
		Telomerase activity is closely linked to attainment of cellular immortality, a step in carcinogenesis, while lack of such activity contributes to cellular senescence.
		Acting in concert with oncogenes or mutated tumor suppressor genes, telomerase expression is associated with the malignant phenotype and is found in 85% to 90% of all human cancers (Holt et al, 1996).
		Strong telomerase activity is found in progenitor stem cells and activated lymphocytes in vitro as well as in vivo, indicating that cells with high growth requirements can readily upregulate telomerase.
	www.thedoctorslounge.net /oncology/articles/telomleuk (1010 words)

	Biochemists report discovery of structure of major piece of telomerase; implications for cancer
		Although it is not known whether telomerase activation is just a marker for cancer cells or involved in causing it, telomerase is an attractive target for development of anti-cancer drugs by pharmaceutical companies.
		The domain of telomerase whose structure the biochemists have determined is essential for telomerase to add nucleotides to telomeres.
		For telomerase to be active, it needs the telomerase RNA and a protein called human telomerase reverse transcriptase, which is related to the reverse transcriptase protein that is important for replicating the AIDS virus.
	www.medicalnewstoday.com /medicalnews.php?newsid=21017 (969 words)

	Telomere - Wikipedia, the free encyclopedia
		Telomeres are extended by telomerases, specialized reverse transcriptase enzymes that are involved in synthesis of telomeres in humans and many other, but not all, organisms.
		In humans, the telomere sequence is a repeating string of TTAGGG, between 3 and 20 kilobases in length.
		There are theories that the steady shortening of telomeres with each replication in somatic (body) cells may have a role in senescence and in the prevention of cancer.
	en.wikipedia.org /wiki/Telomere (1259 words)

	Geron - Activation of Telomerase in Normal Human Cells Extends Their Life-Span; Important Implications for Medicine
		This achievement, which was accomplished by introducing the enzyme telomerase into normal mortal cells, provides definitive evidence that the triggering mechanism for aging, or senescence, in human cells is telomere shortening.
		Telomerase uses the RNA component to direct the synthesis of the repeated sequence (TTAGGG), and the fusion of the building blocks of DNA is accomplished by the catalytic compound hTRT.
		Inhibition of telomerase activity in cancer cells, on the other hand, causes them to stop growing and die once their telomeres become so short that their chromosomes are unstable.
	www.geron.com /showpage.asp?code=scibackta (1772 words)

	télomérase inhibiteur
		Specifically, Geron scientists have blocked human telomerase in tumor cell lines in vitro using both a small molecule compound and an antisense compound to the human telomerase RNA component.
		Telomerase inhibition is therefore expected to have delayed efficacy as cancer cell telomeres resume normal shortening.
		The Company believes that telomerase is a universal and highly specific marker of cancer and, therefore, the detection and quantification of telomerase may have significant clinical utility for cancer diagnosis.
	www.esculape.com /biologie/telomeraseinhib.html (1387 words)

	Telomerase.org (Site not responding. Last check: 2007-10-07)
		Today I was reading an abstract at www.pubmed.com on how inhibiting telomerase may cause early onset of old-age related diseases such as osteoporosis. Going after telomerase is something we should be very careful about.
		Telomerase was discovered by Elizabeth Blackburn and Carol Greider.
		Telomerase was used to rejuvenate the white blood cells in AIDS patients, increasing resistance to the disease.
	www.telomerase.org (1079 words)

	Inhibition of Telomerase Activity in Human Cancer Cells by RNA Interference -- Kosciolek et al. 2 (3): 209 -- Molecular ...
		Telomerase RNA was quantified by a reverse transcriptase-PCR
		The telomerase activity of the clones isolated is shown in Table 1.
		The telomerase RNA content was determined by a reverse transcriptase-PCR assay as described in "Materials and Methods" using either 50 or 100 ng RNA.
	mct.aacrjournals.org /cgi/content/full/2/3/209 (4817 words)

	Telomerase: Facts and details from Encyclopedia Topic (Site not responding. Last check: 2007-10-07)
		The telomerase binds to the to the 5' single stranded end of a chromosome.
		A telomere is a region of highly repetitive dna at the end of a chromosome similar to the plastic tips on the end of a shoe lace....
		The genetic code is a set of rules, which maps dna sequences to proteins in the living cell, and is employed in the process of protein synthesis....
	www.absoluteastronomy.com /encyclopedia/t/te/telomerase.htm (1606 words)

	txt001nkg: Telomerase-directed molecular therapeutics (Site not responding. Last check: 2007-10-07)
		A study of telomerase activity in small-cell versus non-small-cell lung cancers (Ref. 40) recorded a high level of TRAP positivity in 100%; of samples from primary small-cell lung cancers and their metastases, but only 69.2–88.5% positivity, varying with histology, in primary non-small-cell samples, and only 50% positivity in metastases derived from non-small-cell lesions.
		Although AZT is not specifically targeted to telomerase, and the activated analogue is a general inhibitor of polymerase activity, several studies have examined the effects of AZT on telomerase activity in cancer cell lines and have shown an inhibitory effect, although the therapeutic value is uncertain.
		Telomerase expression and activity can vary greatly even among cancers, yet it is clear that many cancers have high levels of telomerase and are totally dependent on this activity for their long-term survival.
	www-ermm.cbcu.cam.ac.uk /02004507h.htm (9761 words)

	Telomerase, TRF1, TRF2, TP1, Tankyrase antibodies and positive controls,
		Telomerase is an unusual RNA-dependent DNA polymerase that uses and RNA component to specify the addition of telomere.
		In ciliated protozoa and yeast, telomere length is maintained by regulating the activity of telomerase.
		Telomerase activity has been detected in a wide variety of eukaryotic species, including yeast, ciliates, Xenopus, mouse and human.
	www.4adi.com /flr/telomerase.html (659 words)

	Hayflick Licked: Telomerase Lengthens Life of Normal Human Cells
		An enzyme, telomerase, which extends the telomere, had been discovered just before, and Cooke wondered whether it might be inactive in normal human cells.
		Telomerase, then, is the little bit of Scotch tape that gives new life to a frayed shoelace.
		Equally exciting is the possibility that telomerase could act as a marker for cancers that are otherwise difficult to detect.
	www.sciencewatch.com /may-june2000/sw_may-june2000_page8.htm (902 words)

	COUNTING MECHANISMS FOR TELOMERE LENGTH (Site not responding. Last check: 2007-10-07)
		Telomerase, an RNA-dependent DNA polymerase, is bound to an RNA template with a sequence complementary to this telomeric repeat sequence.
		This ribonucleoprotein complex consisting of the telomerase and the RNA template catalyzes the in vitro and in vivo synthesis of the telmeric repeats.
		The association of the TP1 with telomerase was shown by immunoprecipitating the telomerase activity from the cell extracts by an antiserum to TP1.
	www.bioscience.org /news/scientis/telomer1.htm (213 words)

	Studies of the molecular mechanisms in the regulation of telomerase activity -- LIU 13 (15): 2091 -- The FASEB Journal (Site not responding. Last check: 2007-10-07)
		telomerase RNA and catalytic subunits and with the mosaic of
		with the telomerase RNA subunit and to reverse transcribe telomere
		the telomerase holoenzyme, it is noteworthy that whereas hTEP1
	www.fasebj.org /cgi/content/full/13/15/2091 (6413 words)

	Telomerase
		A complex enzyme composed of several proteins and a strand of ribonucleic acid (RNA), telomerase affixes brief DNA sequences to the ends of chromosomes.
		Since most adult cells do not use telomerase to rebuild their telomeres, scientists have long thought that the dwindling of telomeres pushes cells into senescence.
		While many scientists remain firm proponents of telomerase inhibition as an anticancer strategy, Huber Warner of the National Institute on Aging in Bethesda, Md., says that both camps will have to await the development of inhibitors and their testing in animals.
	www.thehormoneshop.com /telomerase.htm (1005 words)

	Telomeres and telomerase -- Blasco et al. 13 (18): 2353 -- Genes and Development
		The telomerase RNA pseudoknot is critical for the stable assembly of a catalytically active ribonucleoprotein.
		Reverse transcriptase motifs in the catalytic subunit of telomerase.
		In vivo alteration of telomere sequences and senescence caused by mutated Tetrahymena telomerase RNAs.
	www.genesdev.org /cgi/content/full/13/18/2353 (4248 words)

	Science--Telomerase
		To test this hypothesis, two telomerase-negative normal human cell types, retinal pigment epithelial cells and fore-skin fibroblasts, were transfected with vectors encoding the human telomerase catalytic subunit.
		In contrast to telomerase-negative control clones, which exhibited telomere shortening and senescence, telomerase-expressing clones had elongated telomeres, divided vigorously, and showed reduced staining for b-galactosidase, a biomarker for senescence.
		Now in a paper in the 16 January, 1998 issue of Science, the telomeric theory of aging is dramatically resuscitated.Bodnar et al.
	www.sciencemag.org /feature/data/telomerase/telomerase.dtl (500 words)

	A little telomerase isn't enough
		The failure of telomerase to lengthen these telomeres explains why successive generations develop the physical symptoms of the disease at younger ages than their parents or grandparents, say the researchers.
		Mary Armanios, M.D., now an assistant professor of oncology in the Johns Hopkins Kimmel Cancer Center, discovered that the family carried a genetic defect that caused the telomerase protein to be half as effective as normal and that shortening telomeres were to blame for earlier onset.
		When the researchers looked at fifth-generation mice that had by chance inherited their parents' good telomerase copies, giving the animals a full complement of telomerase, they were surprised to find that those mice had the same symptoms and problems as their half-telomerase littermates.
	www.eurekalert.org /pub_releases/2005-12/jhmi-alt122205.php (1093 words)

	Cancer Biog @ NaturalResearch.org (Natural Research) (Site not responding. Last check: 2007-10-07)
		Telomerase mutations remove additional barriers, extending the number of times a cell can divide.
		Other mutations enable the tumor to grow new blood vessels to provide more nutrients, or to metastasize, spreading to other parts of the body.
		A cell that degenerates into a tumor cell does not usually acquire all these properties at once, but its descendant cells are selected to build them.
	www.naturalresearch.org /encyclopedia/Cancer (5642 words)

	Telomerase Activity and Telomere Length in Primary and Metastatic Tumors from Pediatric Bone Cancer Patients -- ... (Site not responding. Last check: 2007-10-07)
		Telomerase Activity and Telomere Length in Primary and Metastatic Tumors from Pediatric Bone Cancer Patients -- SOTILLO-PIÑEIRO et al.
		Telomerase Activity and Telomere Length in Primary and Metastatic Tumors from Pediatric Bone Cancer Patients
		Telomerase activity was detected in 85% of the bone
	www.pedresearch.org /cgi/content/full/55/2/231 (3310 words)

	Natural and pharmacological regulation of telomerase -- Mergny et al. 30 (4): 839 -- Nucleic Acids Research
		Telomerase is composed of two major components: the catalytic subunit and the template RNA (hTR).
		Mutations in two telomerase component (hTR and dyskerin, in red) have been demonstrated to be involved into dyskeratosis congenita (DKC), a progressive bone-marrow failure syndrome (103,104).
		telomerase activity is disabled in immortalised cells (63).
	nar.oxfordjournals.org /cgi/content/full/30/4/839 (8583 words)

	TERC - Telomerase RNA component - aka: hTR, TRC3 - Cancer GeneticsWeb
		Telomerase is an enzyme that adds TTAGGG nucleotide repeats onto the ends of vertebrate chromosomal DNA (telomeres) to compensate for losses that occur with each round of DNA replication.
		A number of studies suggest that telomerase expression is an adverse prognostic factor for lung cancers.
		Telomerase activity in small-cell and non-small-cell lung cancers.
	www.cancerindex.org /geneweb/TERC.htm (308 words)

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