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Telomeres

A tale of ends

Nature volume 403, pages 149–151 (2000)Cite this article

An Erratum to this article was published on 20 January 2000

During the past few years in the field of chromosome biology, much attention has focused on the very tip of the chromosome — the telomere. This is because functional telomeres are essential for continuous cellular proliferation, an observation that has profound implications for our understanding of ageing and cancer. Studies of telomere biology have been aided by the discovery of numerous genes required for telomere replication in ciliates, yeast, mice and humans. But missing from this genetic pantheon has been the nematode worm Caenorhabditis elegans, one of the premier organisms for gene identification and analysis. Now, however, on page 159 of this issue, Ahmed and Hodgkin1 describe an elegant screen for C. elegans mutants with mortal germ lines. The first gene to be characterized from this work, mortal germline-2 (mrt-2), plays double duty in the nucleus — it is required not only for telomere replication, but also for monitoring damaged DNA.

The strategy used to identify the mrt-2 gene was based, in part, on what we know about telomere dysfunction in other systems. For growth of single-celled eukaryotes such as ciliates and yeast, continuous telomere replication is needed. Loss of telomerase — the enzyme responsible for replicating telomeres — results in a cell line that can be maintained for only a limited number of cell divisions, whereas restoration of telomerase function confers unlimited cellular propagation2,3. In mammals, by contrast, telomere replication is highly regulated, and many tissues do not sustain high levels of telomerase. However, the germ line, which is passed from one next generation to the next, is an immortal cell lineage that must be able to proliferate indefinitely. Here, as expected, telomeres are maintained at their full length4, and, if telomerase is eliminated by a directed knockout in mice, the result is eventual sterility5.

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Figure 1: Proposed set of common events at DNA double-strand breaks and telomeres.

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  1. the Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza , Houston, 77030, Texas, USA

    Victoria Lundblad

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  1. Victoria Lundblad
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Correspondence to Victoria Lundblad.

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Lundblad, V. A tale of ends. Nature 403, 149–151 (2000). https://doi.org/10.1038/35003085

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