telomerase


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telomerase

 [tĕ-lo´mer-ās]
a DNA polymerase involved in the formation of telomeres and the maintenance of telomere sequences during replication.

tel·o·me·rase

(tel-ō'mĕ-rās),
A reverse transcriptase comprising an RNA template, which acts as a die for the TTAGGG sequence, and a catalytic protein component that is not found in normal, aging somatic cells. Telomerase mediates the repair or preservation of telomere regions (terminal sequences) of chromosomes.

The aging process that takes place in normal somatic cells and the natural limit on the number of times such cells can undergo mitosis involve a sequential shortening of telomeres due to failure of terminal sequences to be replicated during mitosis. Cells in which this shortening does not occur (cancer cells, germ cells, hematopoietic stem cells, and others) display a transient expression of telomerase, which not only delays the erosion of telomeres but actually adds DNA bases to telomeres. Experimental transfection of a gene for the catalytic component of telomerase into normal, aging cells results in extension of telomeres. Restoring telomere length appears to reset gene expression, cell morphology, and the replicative life span. It has therefore been suggested that such procedures may permit therapeutic modification of the cellular mechanisms underlying age-related diseases such as atherosclerosis, osteoarthritis, macular degeneration, and Alzheimer dementia. Cellular aging is but one element of clinical aging, however, others being heredity and environment. Although telomerase expression is an important marker of malignancy, it is not itself the cause of cancer. Telomerase expression and telomere lengthening apparently do not alter normal cell cycle control, chromosome complement, or cell morphology.

telomerase

/telo·mer·ase/ (tĕ-lo´mer-ās) a DNA polymerase involved in the formation of telomeres and the maintenance of telomere sequences during replication.

telomerase

(tə-lŏm′ə-rās′, -rāz′)
n.
An enzyme that is found in the telomeres of chromosomes in germ cells, stem cells, and most cancer cells and that preserves the length of telomeres across cell divisions.

telomerase

[tə·lō′mər·ās]
a DNA polymerase involved in the formation of telomeres and the maintenance of telomere sequences during replication.

telomerase

The enzyme that can reforms the TELOMERES at the ends of chromosomes. Telomerase is found in cancers and is able to prevent the shortening that would otherwise occur with repeated replication, thus allowing cancerous cells in culture to achieve immortality. Telomerase consists of two subunits, telomerase reverse transcriptase and an RNA component.

telomerase

an enzyme that adds specific nucleotides to the ends of eukaryotic chromosomes to form TELOMERES.
References in periodicals archive ?
Comparison of telomerase assays using TRAP/PCR, TRAP/real-time PCR, and hTERT mRNA/RT-PCR.
One study found that telomerase appears to be even more accurate than examining cells under the microscope, now the standard way of judging whether they are cancerous.
Controlled activation of the enzyme telomerase may restore the regenerative and functional capacity of cells in various organ systems impacted by senescence, injury or chronic disease.
Although telomerase was discovered in 1985, exactly how this enzyme repairs telomeres to enable cancer cells to divide and grow was largely unknown.
Andrews, founder of Sierra Sciences, LLC and one of the principal discoverers of the telomerase genes, said: "Cleopatra, Ponce de Leon, and untold others throughout the ages have searched for the secrets of youth.
16 [micro]g of primer], incubated at 30 [degrees]C for 30 min, and then heated to 90 [degrees]C for 3 min to inactivate the telomerase activity.
Keynote Presentation: Targeting Telomerase for Cancer Therapeutics
It is believed that telomerase activity is required in essentially all tumours for the immortalisation of a subset of cells, including cancer stem cells.
When telomerase isn't active, each time our cells divide, the telomeres get shorter.
In most tissues, telomerase turns off during development, after which telomeres shorten and limit the number of times a cell can divide, eventually losing their capping function--similar to the shoelace tip falling off.
Telomerase protects the ends of chromosomes from being lost in the process of cell division and, thus, prevents that the cell ages and dies.
But in some, stem cells and cancer cells for example, telomeres are replenished through the action of telomerase, an enzyme that has both protein and ribonucleic acid, or RNA, components.