Premature Aging in Mice Deficient in DNA Repair and Transcription

TLDR

Accumulation of DNA damage is thought to drive aging, and in TTD mice unrepaired damage may compromise transcription, causing loss of critical gene function and increased apoptosis. The study aims to support the DNA‑damage hypothesis by examining XPD‑mutant mice, a model of trichothiodystrophy. The authors used XPD‑mutant mice, which lack a DNA helicase involved in repair and transcription, to investigate aging phenotypes. TTD mice display multiple premature‑aging features such as osteoporosis, kyphosis, osteosclerosis, early greying, cachexia, infertility, and shortened lifespan, and the phenotype is further accelerated by an additional XPA mutation that heightens sensitivity to oxidative DNA damage.

Abstract

One of the factors postulated to drive the aging process is the accumulation of DNA damage. Here, we provide strong support for this hypothesis by describing studies of mice with a mutation in XPD , a gene encoding a DNA helicase that functions in both repair and transcription and that is mutated in the human disorder trichothiodystrophy (TTD). TTD mice were found to exhibit many symptoms of premature aging, including osteoporosis and kyphosis, osteosclerosis, early greying, cachexia, infertility, and reduced life-span. TTD mice carrying an additional mutation in XPA , which enhances the DNA repair defect, showed a greatly accelerated aging phenotype, which correlated with an increased cellular sensitivity to oxidative DNA damage. We hypothesize that aging in TTD mice is caused by unrepaired DNA damage that compromises transcription, leading to functional inactivation of critical genes and enhanced apoptosis.