BOR - Papers in Press, published online ahead of print
October 23, 2002.
Biol Reprod 2002, 10.1095/biolreprod.102.008920
BIOLOGY OF REPRODUCTION 68, 717721 (2003)
DOI: 10.1095/biolreprod.102.008920
© 2003 by the Society for the Study of Reproduction, Inc.
Function of DNA-Protein Kinase Catalytic Subunit During the Early Meiotic Prophase Without Ku70 and Ku861
Geert Hamer2,a,b,
Hermien L. Roepers-Gajadiena,b,
Annemarie van Duyn-Goedhartc,
Iris S. Gademand,
Henk B. Kald,
Paul P.W. van Buulc,
Terry Ashleye, and
Dirk G. de Rooija,b
a Department of Endocrinology, Faculty of Biology, Utrecht University, 3584 CH Utrecht, The Netherlands
b Department of Cell Biology, UMCU, 3584 CX Utrecht, The Netherlands
c MCG-Department of Radiation Genetics and Chemical Mutagenesis, Sylvius Laboratory, Leiden University, 2333 AL Leiden, The Netherlands
d Department of Radiotherapy, UMCU, 3584 CX Utrecht, The Netherlands
e Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510
All components of the double-stranded DNA break (DSB) repair complex DNA-dependent protein kinase (DNA-PK), including Ku70, Ku86, and DNA-PK catalytic subunit (DNA-PKcs), were found in the radiosensitive spermatogonia. Although p53 induction was unaffected, spermatogonial apoptosis occurred faster in the irradiated DNA-PKcs-deficient scid testis. This finding suggests that spermatogonial DNA-PK functions in DNA damage repair rather than p53 induction. Despite the fact that early spermatocytes lack the Ku proteins, spontaneous apoptosis of these cells occurred in the scid testis. The majority of these apoptotic spermatocytes were found at stage IV of the cycle of the seminiferous epithelium where a meiotic checkpoint has been suggested to exist. Meiotic synapsis and recombination during the early meiotic prophase induce DSBs, which are apparently less accurately repaired in scid spermatocytes that then fail to pass the meiotic checkpoint. The role for DNA-PKcs during the meiotic prophase differs from that in mitotic cells; it is not influenced by ionizing radiation and is independent of the Ku heterodimer.
1 This work was supported by the J.A. Cohen Institute for Radiopathology and Radiation Protection, Leiden, The Netherlands.
2 Correspondence: Geert Hamer, Department of Endocrinology, Faculty of Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. FAX: 31 30 2532837; e-mail: g.hamer{at}bio.uu.nl
Copyright © 2003 by the Society for the Study of Reproduction.