Research by the USA’s National Human Genome Research Institute describes epigenetic clocks that apply to both dogs and humans. The findings offer confidence that future treatments to delay or reverse epigenetic age in one species will have the same effect in another species.
Epigenetic clocks — a technique that measures DNA methylation profiles — are used to estimate the biological age of humans and animals. These clocks can provide a better indicator of an organism’s functional capacity than its actual, chronological age. Until now though, epigenetic clocks only applied to one species at a time. The recent study in PNAS presents two highly accurate human-dog dual species epigenetic clocks which may facilitate antiaging treatments from canine to human use – or vice versa.
Who’s a good (model) boy?
Research into the ageing process typically relies on animal models, such as dogs. Dogs are similar to us in many ways, they suffer from many of the same age-related disorders such as arthritis, hypothyroidism, and diabetes, and their DNA undergoes similar age-related changes. But it is important to know to what extent the dog model accurately reflects the process that occurs in humans.
To test if epigenetic clocks could apply to both dogs and humans, the authors took over 700 DNA samples from 93 breeds of dog – from giant great Danes to tiny toy poodles. They also used human DNA samples (over 1300) derived from either blood or tissue, then profiled the dog and human samples on the same methylation array.
Tick-tocking in time
Overall, the authors identified two so-called human–dog clocks; one for predicting chronological age and one for predicting relative age. The authors note that these epigenetic clocks may facilitate the ready translation from dog to human (or vice versa) of antiaging treatments and preventive medicine.
“[This study] demonstrates that, at least at the DNA level, there are remarkable similarities in the ageing process between dogs and humans,” they say.
The authors then researched dog clocks further. Small breeds of dog live much longer than large breeds, so dogs offer researchers the unique chance to study the relationship between size and lifespan within one species. They developed an epigenetic clock that predicated a dog’s lifespan and conducted epigenome-wide association studies that revealed individual methylation sites that could underlie the inverse relationship between breed weight and lifespan. The findings from this study provide biomarkers that could be used to measure the ageing of dogs and possibly their health status.
Written by Charlotte Harrison, Science Writer
Image Credit: Canva