Tuesday, July 20, 2010

The Aging Brain: Endangered by Runaway Development?

Mehmet Somel, a Turkish researcher doing post-doctoral work in Shanghai, has uncovered some fascinating genetic evidence suggesting that inappropriate-for-age gene regulation may be endangering aging brains:
Researchers have now identified a gene regulatory link between changes in the young and aging brain.

The brain undergoes rapid growth and development in the early years of life and then degenerates as we progress into old age, yet little is known about the biological processes that distinguish brain development and aging.

Underlying brain development is the complex and coordinated process of gene regulation.

"In development, many genes are turned on and off by regulators, such as transcription factors and microRNAs. The question is, do all of these regulatory processes cease once adulthood is reached, or are they still active in aging?" said Mehmet Somel, postdoctoral researcher at the Shanghai Institutes for Biological Sciences.

The researchers investigated messenger RNA (mRNA), microRNA, and protein expression changes in the prefrontal cortex of humans and rhesus macaque monkeys over the life span of each species.

The group found that distinct patterns of gene regulation in the prefrontal cortex do not stop at maturity, instead persisting into old age, a phenomenon that was observed for many different functional processes.

...The researchers showed that this process begins as early as three to four years of age, suggesting that these changes may be normal developmental regulation that continues long into old age.

While this regulation is likely to be beneficial during development, at old age continuation of the gene regulation, or "runaway" development, might be detrimental.

Interestingly, they found the runaway neuronal development to be conserved in macaques, but it occurs an accelerated rate.

Because the regulatory processes progress much faster, the authors suggest that this could be a significant contributor toward limiting the life span of macaques to only about one-third that of humans. _SiFy
Researchers will now need to determine whether a more "age-appropriate" pattern of gene regulation would allow for persistence of normal brain functioning further into old age.

It is known that DNA repair loses efficiency with increasing age. If inappropriate genes are consistently "over-clocked" at levels more appropriate to younger ages, the compounding of genetic errors due to inefficient DNA repair would occur more quickly and take on more significance.

This is a fascinating area of study, well worth following.



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