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Premature ageing in mice expressing defective mitochondrial DNA polymerase

Premature ageing in mice expressing defective mitochondrial DNA polymerase Point mutations and deletions of mitochondrial DNA (mtDNA) accumulate in a variety of tissues during ageing in humans 1 , monkeys 2 and rodents 3 . These mutations are unevenly distributed and can accumulate clonally in certain cells, causing a mosaic pattern of respiratory chain deficiency in tissues such as heart 4 , skeletal muscle 5 and brain 6 . In terms of the ageing process, their possible causative effects have been intensely debated because of their low abundance and purely correlative connection with ageing 7,8 . We have now addressed this question experimentally by creating homozygous knock-in mice that express a proof-reading-deficient version of PolgA, the nucleus-encoded catalytic subunit of mtDNA polymerase. Here we show that the knock-in mice develop an mtDNA mutator phenotype with a threefold to fivefold increase in the levels of point mutations, as well as increased amounts of deleted mtDNA. This increase in somatic mtDNA mutations is associated with reduced lifespan and premature onset of ageing-related phenotypes such as weight loss, reduced subcutaneous fat, alopecia (hair loss), kyphosis (curvature of the spine), osteoporosis, anaemia, reduced fertility and heart enlargement. Our results thus provide a causative link between mtDNA mutations and ageing phenotypes in mammals. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Springer Journals

Premature ageing in mice expressing defective mitochondrial DNA polymerase

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References (40)

Publisher
Springer Journals
Copyright
Copyright © 2004 by Macmillan Magazines Ltd.
Subject
Science, Humanities and Social Sciences, multidisciplinary; Science, Humanities and Social Sciences, multidisciplinary; Science, multidisciplinary
ISSN
0028-0836
eISSN
1476-4687
DOI
10.1038/nature02517
Publisher site
See Article on Publisher Site

Abstract

Point mutations and deletions of mitochondrial DNA (mtDNA) accumulate in a variety of tissues during ageing in humans 1 , monkeys 2 and rodents 3 . These mutations are unevenly distributed and can accumulate clonally in certain cells, causing a mosaic pattern of respiratory chain deficiency in tissues such as heart 4 , skeletal muscle 5 and brain 6 . In terms of the ageing process, their possible causative effects have been intensely debated because of their low abundance and purely correlative connection with ageing 7,8 . We have now addressed this question experimentally by creating homozygous knock-in mice that express a proof-reading-deficient version of PolgA, the nucleus-encoded catalytic subunit of mtDNA polymerase. Here we show that the knock-in mice develop an mtDNA mutator phenotype with a threefold to fivefold increase in the levels of point mutations, as well as increased amounts of deleted mtDNA. This increase in somatic mtDNA mutations is associated with reduced lifespan and premature onset of ageing-related phenotypes such as weight loss, reduced subcutaneous fat, alopecia (hair loss), kyphosis (curvature of the spine), osteoporosis, anaemia, reduced fertility and heart enlargement. Our results thus provide a causative link between mtDNA mutations and ageing phenotypes in mammals.

Journal

Nature – Springer Journals

Published: May 27, 2004

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