Study of 894 dogs links body size to faster age-related changes in DNA methylation

Study of 894 dogs links body size to faster age-related changes in DNA methylation

On October 8, Science published a study from the Dog Aging Project, which studies aging in companion dogs. The researchers analyzed 1 640 DNA methylation profiles from 894 animals and linked body size to the rate of molecular aging.

Large dog breeds generally have shorter lifespans than small breeds, making dogs a useful species for studying the relationship between body size and the rate of aging. The researchers examined whether this difference was reflected in DNA methylation, the chemical marks on DNA that influence how regions of the genome function. Epigenetic clocks, statistical models that estimate age from the pattern of these marks, predicted mortality. Age-related changes in methylation occurred faster in larger dogs and in males, both of which have shorter average lifespans.

Sex and body size were associated with distinct methylation patterns. Sex-related changes were concentrated on the X chromosome. The association between body size and methylation was particularly pronounced in transposons, DNA sequences that can copy themselves and insert those copies elsewhere in the genome.

LINE1 elements are a type of transposon. In the full earlier preprint from the same research group, methylation at LINE1-associated sites declined with age; in giant dogs, it declined by 0,26 percentage points per year faster than in small dogs. Methylation helps cells keep these elements suppressed, so LINE1 may be one of the molecular links between body size and the rate of aging.