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Review
. 1999 Mar 30;96(7):3339-41.
doi: 10.1073/pnas.96.7.3339.

Crisis intervention: the role of telomerase

A J Lustig
Review

Crisis intervention: the role of telomerase

A J Lustig. Proc Natl Acad Sci U S A. .
No abstract available

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Figures

Figure 1
Figure 1
The effect of ectopic expression of hTERT on growth and telomere size in cells cultured in vitro. As shown in red, when primary cultures are grown in vitro, telomere size decreases. Cells undergo population doublings until they reach a point, termed senescence (or M1), where populations cease to grow and telomere size is stabilized. One way to overcome senescence is expression of ectopic hTERT (green), which increases telomere size and allows continual growth. In the presence of oncogenic viruses such as SV40 virus large T antigen (and the loss of p53 or pRB functions), cells are capable of passing the senescence point (blue) and continuing to grow, with concomitant loss of telomeric sequences. This process continues until the population reaches a point called crisis (or M2) stage. At crisis, both a high rate of cell death and chromosome abnormalities have been observed. Of interest, this M2 arrest of growth appears to correlate with a particular threshold telomere length. Crisis can be overcome, however, by expression of hTERT in cells approaching M2 (yellow), with telomeres ultimately stabilizing at sizes close to or below the M2 threshold as defined in cells lacking ectopic expression of hTERT.
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