Telomere capping

Telomeres protect the ends of chromosomes and prevent chromosomal end-to-end fusions. The DNA-dependent protein kinase (DNA-PK) has been implicated in DNA repair and telomere maintenance. In the December 18 Proceedings of the National Academy of Sciences, David Gilley and researchers at the Lawrence Berkeley National Laboratory report the use of knockout mice to examine the function of the DNA-PK catalytic subunit (Proc Natl Acad Sci USA 2001, 98:15084-15088). Analysis of fibroblast and primary cultured kidney cells lacking DNA-PK catalytic subunit revealed no changes in telomere length, but high levels of telomere fusions. These observations differ from those seen in SCID (severe combined immune deficiency) mice, which have a genetically altered DNA-PK catalytic subunit gene.