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. 2014 Apr 16;9(4):e93568.
doi: 10.1371/journal.pone.0093568. eCollection 2014.

The progeroid phenotype of Ku80 deficiency is dominant over DNA-PKCS deficiency

Erwin Reiling  1 , Martijn E T Dollé  2 , Sameh A Youssef  3 , Moonsook Lee  4 , Bhawani Nagarajah  2 , Marianne Roodbergen  2 , Piet de With  2 , Alain de Bruin  3 , Jan H Hoeijmakers  5 , Jan Vijg  4 , Harry van Steeg  6 , Paul Hasty  7
Affiliations

The progeroid phenotype of Ku80 deficiency is dominant over DNA-PKCS deficiency

Erwin Reiling et al. PLoS One. .

Abstract

Ku80 and DNA-PKCS are both involved in the repair of double strand DNA breaks via the nonhomologous end joining (NHEJ) pathway. While ku80-/- mice exhibit a severely reduced lifespan and size, this phenotype is less pronounced in dna-pkcs-/- mice. However, these observations are based on independent studies with varying genetic backgrounds. Here, we generated ku80-/-, dna-pkcs-/- and double knock out mice in a C57Bl6/J*FVB F1 hybrid background and compared their lifespan, end of life pathology and mutation frequency in liver and spleen using a lacZ reporter. Our data confirm that inactivation of Ku80 and DNA-PKCS causes reduced lifespan and bodyweights, which is most severe in ku80-/- mice. All mutant mice exhibited a strong increase in lymphoma incidence as well as other aging-related pathology (skin epidermal and adnexal atrophy, trabacular bone reduction, kidney tubular anisokaryosis, and cortical and medullar atrophy) and severe lymphoid depletion. LacZ mutation frequency analysis did not show strong differences in mutation frequencies between knock out and wild type mice. The ku80-/- mice had the most severe phenotype and the Ku80-mutation was dominant over the DNA-PKCS-mutation. Presumably, the more severe degenerative effect of Ku80 inactivation on lifespan compared to DNA-PKCS inactivation is caused by additional functions of Ku80 or activity of free Ku70 since both Ku80 and DNA-PKCS are essential for NHEJ.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Breeding strategy to generate the knockout cohorts.
Ku80+/− and dna-pkcs +/− animals are backcrossed for multiple generations to C57Bl6/J-pUR288 (left of dashed line) and FVB (right of dashed line) background. Double heterozygous knock out C57BL6/J male mice are crossed with double heterozygous knock out FVB female mice. Using this strategy all four desired cohorts are generated as F1 hybrids (grey boxes).
Figure 2
Figure 2. Mean body weights.
(A) Males. (B) Females.
Figure 3
Figure 3. Survival curves.
Median survivals are shown in the figure legends in parentheses. dna-pkcs−/− mice live significantly longer compared to ku80−/− mice in both male (p = 0.01) and females (p = 8.7*10−6) mice. Survival of double knock out mice is identical to ku80−/−. (A) Males. (B) Females.
Figure 4
Figure 4. LacZ mutant frequency.
Error bars represent standard deviation. (A) Mutant frequency in liver. (B) Mutant frequency in spleen.
See this image and copyright information in PMC

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