Transient Expression of Human Telomerase Extends the Life Span of Normal Human Fibroblasts

Steinert, Susanne; Shay, Jerry W.; Wright, Woodring E.

doi:10.1006/bbrc.2000.3080

Cited by 124 publications

(95 citation statements)

References 21 publications

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“…By creating untransformed human cells with varying telomere lengths, we confirmed that replicative life span is proportional to telomere length (48,52). We also found that experimental lengthening of the telomeres, at least within the limits achieved here, did not compromise cell proliferation or cause any obvious change in phenotype.…”

Section: Figsupporting

confidence: 73%

“…Our strategy for conditional telomerase expression, flanking hTERT by loxP sites, resembles that of Steinert et al (52). Our vector, however, conferred histidinol resistance prior to Creinduced excision and puromycin resistance after excision.…”

Section: Figmentioning

confidence: 99%

“…After hTERT expression, telomeres quickly equilibrate to an average length that depends on the cell type. In some cases, the telomeres elongate (12,13,52), but in other cases they shorten (56) or show only minor length changes (57). 2 Thus, telomerase may influence the IR response indirectly by altering telomere length.…”

Section: Figmentioning

confidence: 99%

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Reversible Manipulation of Telomerase Expression and Telomere Length

Rubio

Kim

Campisi

2002

Journal of Biological Chemistry

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Most human cells do not express telomerase and irreversibly arrest proliferation after a finite number of divisions (replicative senescence). Several lines of evidence suggest that replicative senescence is caused by short dysfunctional telomeres, which arise when DNA is replicated in the absence of adequate telomerase activity. We describe a method to reversibly bypass replicative senescence and generate mass cultures that have different average telomere lengths. A retrovirus carrying hTERT flanked by excision sites for Cre recombinase rendered normal human fibroblasts telomerase-positive and replicatively immortal. Superinfection with retroviruses carrying wild-type or mutant forms of TIN2, a negative regulator of telomere length, created telomerase-positive, immortal populations with varying average telomere lengths. Subsequent infection with a Creexpressing retrovirus abolished telomerase activity, creating mortal cells with varying telomere lengths. Using these cell populations, we show that, after hTERT excision, cells senesce with shorter telomeres than parental cells. Moreover, long telomeres, but not telomerase, protected cells from the loss of division potential caused by ionizing radiation. Finally, although telomerase-negative cells with short telomeres senesced after fewer doublings than those with long telomeres, telomere length per se did not correlate with senescence. Our results support a role for telomere structure, rather than length, in replicative senescence.

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Section: Figsupporting

confidence: 73%

Section: Figmentioning

confidence: 99%

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Reversible Manipulation of Telomerase Expression and Telomere Length

Rubio

Kim

Campisi

2002

Journal of Biological Chemistry

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“…These results also suggest that change in telomere length is not a prerequisite for the alteration in telomere-nuclear matrix interaction or transcription. Hemann et al (2001) and Steinert et al (2000) have demonstrated in mouse and human cells that the shortest telomere, not average telomere length, is critical for cell viability and chromosome stability. Therefore, the results showing no change in the average telomere length are in agreement with the maintenance of the Figure 4 Kinetics of hTERT interaction with telomeres and alteration of gene expression.…”

Section: Htert Expression Influences Telomere-nuclear Matrix Associationmentioning

confidence: 99%

hTERT associates with human telomeres and enhances genomic stability and DNA repair

et al. 2003

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Ectopic expression of telomerase in telomerase-silent cells is sufficient to overcome senescence and to extend cellular lifespan. We show here that the catalytic subunit of human telomerase (hTERT) crosslinks telomeres. This interaction is blocked by the telomere repeat binding factor 1, but not by a dominant negative form of this protein. It is also abolished by destruction of the RNA component of telomerase as well as by mutations in the hTERT protein.Ectopic expression of hTERT leads to transcriptional alterations of a subset of genes and changes in the interaction of the telomeres with the nuclear matrix. This is associated with reduction of spontaneous chromosome damage in G 1 cells, enhancement of the kinetics of DNA repair and an increase in NTP levels. The effect on DNA repair is likely indirect as TERT does not directly affect DNA end rejoining in vitro or meiotic recombination in vivo. The observed effects of hTERT occurred rapidly before any significant lengthening of telomeres was observed. Our findings establish an intimate relationship between hTERT-telomere interactions and alteration in transcription of a subset of genes that may lead to increased genomic stability and enhanced repair of genetic damage. These novel functions of telomerase are distinct from its known effect on telomere length and have potentially important biological consequences.

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“…To control gene expression, Cre/lox recombination system may be useful to elongate critically short telomeres as reported in normal human ®broblast (Steinert et al, 2000). The 38 kDa Cre recombinase from bacteriophage P1 catalyzes sitespeci®c recombination between 34 bp repeats termed loxP.…”

Section: Prospectivementioning

confidence: 99%