Defective embryonic neurogenesis in Ku-deficient but not DNA-dependent protein kinase catalytic subunit-deficient mice

Defective embryonic neurogenesis in Ku-deficient but not DNA-dependent protein kinase catalytic subunit-deficient mice

^*Howard Hughes Medical Institute, The Children's Hospital, and Center for Blood Research, and Department of Genetics, Harvard Medical School, Boston, MA 02115; ^‡Department of Neurology, The Children's Hospital, Boston, MA 02115; ^§Lexicon Genetics, 4000 Research Forest Drive, The Woodlands, TX 77381; and ^¶Department of Pharmacology, Neuroscience Program, School of Medicine, University of California, San Diego, La Jolla, CA 92093

Contributed by Frederick W. Alt

Abstract

Mammalian nonhomologous DNA end joining employs Ku70, Ku80, DNA-dependent protein kinase catalytic subunit (DNA-PKcs), XRCC4, and DNA ligase IV (Lig4). Herein, we show that Ku70 and Ku80 deficiency but not DNA-PKcs deficiency results in dramatically increased death of developing embryonic neurons in mice. The Ku-deficient phenotype is qualitatively similar to, but less severe than, that associated with XRCC4 and Lig4 deficiency. The lack of a neuronal death phenotype in DNA-PKcs-deficient embryos and the milder phenotype of Ku-deficient versus XRCC4- or Lig4-deficient embryos correlate with relative leakiness of residual end joining in these mutant backgrounds as assayed by a V(D)J recombination end joining assay. We conclude that normal development of the nervous system depends on the four evolutionarily conserved nonhomologous DNA end joining factors.

Footnotes

↵ † Y.G., J.S., and Y.G. contributed equally to this work.
↵ ‖ To whom reprint requests should be addressed. E-mail: alt{at}rascal.med.harvard.edu.
Abbreviations:

DSB,

double-strand break;

NHEJ,

nonhomologous end joining;

DSBR,

DSB repair;

DNA-PKcs,

DNA-dependent protein kinase catalytic subunit;

RS,

recombination signal sequences;

CNS,

central nervous system;

VZ,

ventricular zone;

IZ,

intermediate zone;

ML,

mantle layer;

TUNEL,

terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labeling;

En,

embryonic day n;

MEF,

murine embryonic fibroblast;

Pn,

postnatal day n