telomerase


Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

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 ?
When telomerase isn't active, each time our cells divide, the telomeres get shorter.
Telomerase activity was measured using commercially available kit according to the kit instruction (Telomerase activity kit, Roche Company Ltd.
Preclinical studies have shown that inhibiting telomerase causes tumor cells to lose immortality, reinitiate telomere shortening, and eventually die.
In most of the tissue samples of melanomas of all stages they found alterations in the telomerase gene switch, which the researchers clearly identified as typical consequences of sun exposure.
Telomerase is already targeted by some anti-cancer drugs, but success has been mixed.
The results clearly demonstrated that there could be a broad spectrum of karyotype abnormalities and heterogeneity in the telomerase activity in different FAB subtypes of MDS of and ANLL patients.
Most normal cells do not divide frequently; therefore, their chromosomes are not at risk of shortening and they do not require high telomerase activity.
Very recently, remedies have been developed that could possibly alleviate, abolish, or reverse this "up to now" inevitable fate by activating an enzyme called telomerase, which may help maintain telomere length.
The new study clarifies the active region of telomerase and provides the first view of the telomerase molecule's critical protein component at the atomic level, showing the enzyme's configuration and how it works--a process critical to tumor development and the aging process.
TERT has been shown to contain at least 6 alternative splicing sites (16-20); however, only the full-length TERT transcript is associated with telomerase activity (16-18).
Italian researchers examined 218 men (84 healthy individuals and 134 patients at first diagnosis with bladder cancer) and compared the effectiveness of the telomerase measurement to urine cytology, an examination of cells.