Ku is associated with the telomere in mammals

Ku is associated with the telomere in mammals

^†Life Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545; ^‡Department of Microbiology and Immunology University of California, San Francisco, CA 94143-0414; and ^§Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720

Edited by Joseph G. Gall, Carnegie Institution of Washington, Baltimore, MD, and approved August 31, 1999 (received for review June 14, 1999)

Abstract

Telomeres are specialized DNA/protein complexes that comprise the ends of eukaryotic chromosomes. The highly expressed Ku heterodimer, composed of 70 and 80 K _d subunits (Ku70 and Ku80), is the high-affinity DNA binding component of the DNA-dependent protein kinase. Ku is critical for nonhomologous DNA double-stranded break repair and site-specific recombination of V(D)J gene segments. Ku also plays an important role in telomere maintenance in yeast. Herein, we report, using an in vivo crosslinking method, that human and hamster telomeric DNAs specifically coimmunoprecipitate with human Ku80 after crosslinking. Localization of Ku to the telomere does not depend on the DNA-dependent protein kinase catalytic component. These findings suggest a direct link between Ku and the telomere in mammalian cells.

Footnotes

↵ * Present address: Life Sciences Division, Lawrence Berkeley National Laboratory, Mail stop 74, 1 Cyclotron Road, Berkeley, CA 94720.
↵ ¶ To whom reprint requests should be addressed. E-mail: djchen{at}lbl.gov.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

DNA-PKcs,

DNA-dependent protein kinase catalytic component;

HSF,

human skin fibroblast;

CHO,

Chinese hamster ovary