Stress makes your hair go gray

Jun 11, 2009

Those pesky graying hairs that tend to crop up with age really are signs of stress, reveals a new report in the June 12 issue of Cell.

Researchers have discovered that the kind of "genotoxic stress" that does damage to DNA depletes the melanocyte stem cells (MSCs) within hair follicles that are responsible for making those pigment-producing cells. Rather than dying off, when the going gets tough, those precious stem cells differentiate, forming fully mature melanocytes themselves.

Anything that can limit the stress might stop the graying from happening, the researchers said.

"The DNA in cells is under constant attack by exogenously- and endogenously-arising DNA-damaging agents such as mutagenic chemicals, ultraviolet light and ionizing radiation," said Emi Nishimura of Tokyo Medical and Dental University. "It is estimated that a single cell in mammals can encounter approximately 100,000 DNA damaging events per day."

Consequently, she explained, cells have elaborate ways to repair damaged DNA and prevent the lesions from being passed on to their daughter cells.

"Once stem cells are damaged irreversibly, the damaged stem cells need to be eliminated to maintain the quality of the stem cell pools," Nishimura continued. "We found that excessive genotoxic stress triggers differentiation of melanocyte stem cells." She says that differentiation might be a more sophisticated way to get rid of those cells than stimulating their death.

Nishimura's group earlier traced the loss of hair color to the gradual dying off of the stem cells that maintain a continuous supply of new melanocytes, giving hair its youthful color. Those specialized stem cells are not only lost, they also turn into fully committed pigment cells and in the wrong place.

Now, they show in mice that irreparable , as caused by ionizing radiation, is responsible. They further found that the "caretaker gene" known as ATM (for ataxia telangiectasia mutated) serves as a so-called stemness checkpoint, protecting against MSCs differentiation. That's why people with Ataxia-telangiectasia, an aging syndrome caused by a mutation in the ATM gene, go gray prematurely.

The findings lend support to the notion that genome instability is a significant factor underlying aging in general, the researchers said. They also support the "stem cell aging hypothesis," which proposes that DNA damage to long-lived stem cells can be a major cause for the symptoms that come with age.
In addition to the aging-associated stem cell depletion typically seen in melanocyte stem cells, qualitative and quantitative changes to other body stem cells have been reported in blood , cardiac muscle, and skeletal muscle, the researchers said. Stresses on stem cell pools and genome maintenance failures have also been implicated in the decline of tissue renewal capacity and the accelerated appearance of aging-related characteristics.

"In this study, we discovered that hair graying, the most obvious aging phenotype, can be caused by the genomic damage response through stem cell differentiation, which suggests that physiological hair graying can be triggered by the accumulation of unavoidable DNA damage and DNA-damage response associated with aging through MSC differentiation," they wrote.

Source: Cell Press (news : web)

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User comments : 3

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googleplex
not rated yet Jun 11, 2009
Some people don't get grey hairs. How does this happen if they are exposed to the same environment as the grey haired folks.
However I could not find any reports of elderly people without grey hairs. Has there ever been one exception?
If this article is true then grey hair is a 'litmus test' of environmental exposure to mutogens.
wordofmouth
not rated yet Jun 11, 2009
Yeah,I can go with the idea that environmental influences can accelerate IE:hair greying,however only if the person has a predisposition already within their genes.On average,everyone are basically exposed to all environmental factors,take and give a little,so for me it's down to your genes being the primary influence of all ageing process.
ArtflDgr
not rated yet Jun 12, 2009
Some people don't get grey hairs. How does this happen if they are exposed to the same environment as the grey haired folks.


thats because the left has been lying as to our similarities and abilities.

we are not the same... we dont performa the same, we have natural aptitudes and thigns adn all of those thigns are mediated by our genetics. (if thsi wasnt so, then explain how psychotropics work).

basically we are all different and unique, and not interchangeable parts in a collective...

that means that some of us will take stress better and not turn gray as fast if we have the turn gray faster on stress gene... and some of us will take stress work and so that will then allow the other gene to be stimulated.

that is we are all different to test out which one of us will perform better than antoher. (thats called evolution). and so how we perform and do better or worse is how our fitness and genes are selected for the next generation...

shows you how far from biology collectivism is. collectivism would seek to change aroudn all these variables as if they dont exist.

and thats why you cant understand why it doenst do the same thing if your in the same environment.

environment has been falsely elevated, and that point is taught in school as part of creating the new future.

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