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Newly discovered DNA 'body clock' may unlock secrets of aging

By Catholic Online (NEWS CONSORTIUM)
October 23rd, 2013
Catholic Online (www.catholic.org)

An internal body clock based on DNA, which measures the biological age of our tissues and organs has been discovered by scientists. As we age, a DNA biological clock shows that while many healthy tissues age at the same rate, others age much faster or slower. Diseased organs rate of aging varied widely. Some of them proved to be tens of years "older" than healthy tissue in the same person, according to the clock.

LOS ANGELES, CA (Catholic Online) - Unraveling the mechanisms behind the DNA clock will help scientists understand the aging process. In turn, this will lead to drugs and other procedures to slow it down.

This is creating great interest in the medical community, as scores of incurable diseases that strike in old age.

"Ultimately, it would be very exciting to develop therapy interventions to reset the clock and hopefully keep us young," Steve Horvath, professor of genetics and bio statistics at the University of California in Los Angeles says.

Methylation, a natural process that chemically modifies DNA, varied with age was examined by Horvath along with nearly 8,000 samples of 51 different healthy and cancerous cells and tissues. 

Methylation of 353 DNA markers varied consistently with age and could be used as a biological clock. The clock sped fastest in the years up to around age 20, then slowed down to a steadier rate. Whether the DNA changes cause aging or are caused by aging is an unknown that scientists are now keen to work out.

"Does this relate to something that keeps track of age, or is a consequence of age? I really don't know," Horvath says. "The development of gray hair is a marker of aging, but nobody would say it causes aging," he said.

The clock revealed many heretofore biological secrets. Tests on healthy heart tissue showed that its biological age was around nine years younger than expected. Female breast tissue aged faster than the rest of the body, on average appearing two years older.

Cancerous tissue sped up the clock by an average of 36 years. Some brain cancer tissues taken from children had a biological age of more than 80 years.

"Female breast tissue, even healthy tissue, seems to be older than other tissues of the human body. That's interesting in the light that breast cancer is the most common cancer in women. Also, age is one of the primary risk factors of cancer, so these types of results could explain why cancer of the breast is so common," Horvath said.

Tests revealed that healthy tissue surrounding a breast tumor was on average 12 years older than the rest of the woman's body, the scientist's tests revealed.

Horvath says that the biological clock was reset to zero when cells plucked from an adult were reprogrammed back to a stem-cell-like state. The process for converting adult cells into stem cells, which can grow into any tissue in the body, won the Nobel prize in 2012 for Sir John Gurdon at Cambridge University and Shinya Yamanaka at Kyoto University.

"It provides a proof of concept that one can reset the clock," Horvath says. The scientist now wants to run tests to see how neuro-degenerative and infectious diseases affect, or are affected by, the biological clock.

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