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Hum Mol Genet. 2013 Mar 1;22(5):1017-25. doi: 10.1093/hmg/dds506. Epub 2012 Nov 29.

Polg2 is essential for mammalian embryogenesis and is required for mtDNA maintenance.

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1
Mitochondrial DNA Replication Group, Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.

Abstract

Mammalian mitochondrial DNA (mtDNA) is replicated by the heterotrimeric Pol γ comprised of a single catalytic subunit, encoded by Polg, and a homodimeric accessory subunit encoded by the Polg2 gene. While the catalytic subunit has been shown to be essential for embryo development, genetic data regarding the accessory subunit are lacking in mammalian systems. Here, we describe the generation of heterozygous (Polg2(+/-)) and homozygous (Polg2(-/-)) knockout (KO) mice. Polg2(+/-) mice are haplosufficient and develop normally with no discernable difference in mitochondrial function through 2 years of age. In contrast, the Polg2(-/-) is embryonic lethal at day 8.0-8.5 p.c. with concomitant loss of mtDNA and mtDNA gene products. Electron microscopy shows severe ultra-structural defects and loss of organized cristae in mitochondria of the Polg2(-/-) embryos as well as an increase in lipid accumulation compared with both wild-type (WT) and Polg2(+/-) embryos. Our data indicate that Polg2 function is critical to mammalian embryogenesis and mtDNA replication, and that a single copy of Polg2 is sufficient to sustain life.

PMID:
23197651
PMCID:
PMC3561914
DOI:
10.1093/hmg/dds506
[Indexed for MEDLINE]
Free PMC Article
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