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A UCLA study has uncovered a biological clock embedded in our genomes that may shed light on why our bodies age and how we can slow the process. Published in the Oct. 21 edition of Genome Biology, the findings could offer valuable insights into cancer and stem cell research.
"To fight aging, we first need an objective way of measuring it. Pinpointing a set of biomarkers that keeps time throughout the body has been a four-year challenge," explained Steve Horvath, a professor of human genetics at the David Geffen School of Medicine at UCLA and of biostatistics at the UCLA Fielding School of Public Health. "My goal in inventing this clock is to help scientists improve their understanding of what speeds up and slows down the human aging process."
To create the clock, Horvath focused on methylation, a naturally occurring process that chemically alters DNA. Horvath sifted through 121 sets of data collected previously by researchers who had studied methylation in both healthy and cancerous human tissue.
Gleaning information from nearly 8,000 samples of 51 types of tissue and cells taken from throughout the body, Horvath charted how age affects DNA methylation levels from pre-birth through 101 years. To create the clock, he zeroed in on 353 markers that change with age and are present throughout the body.
Horvath tested the clock’s effectiveness by comparing a tissue’s biological age to its chronological age. When the clock repeatedly proved accurate, he was thrilled — and a little stunned.
Caption: A newly discovered biological clock measures aging throughout the body. Credit: UCLA/Horvath lab
Steve Horvath. DNA methylation age of human tissues and cell types. Genome Biology, 2013; 14 (10): R115 DOI: 10.1186/gb-2013-14-10-r115