Featured Research

from universities, journals, and other organizations

Scientists discover 'fickle' DNA changes in brain

Date:
October 1, 2011
Source:
Johns Hopkins Medical Institutions
Summary:
Scientists investigating chemical modifications across the genomes of adult mice have discovered that DNA modifications in non-dividing brain cells, thought to be inherently stable, instead underwent large-scale dynamic changes as a result of stimulated brain activity. Their report has major implications for treating psychiatric diseases, neurodegenerative disorders, and for better understanding learning, memory and mood regulation.

Johns Hopkins scientists investigating chemical modifications across the genomes of adult mice have discovered that DNA modifications in non-dividing brain cells, thought to be inherently stable, instead underwent large-scale dynamic changes as a result of stimulated brain activity. Their report, in the October issue of Nature Neuroscience, has major implications for treating psychiatric diseases, neurodegenerative disorders, and for better understanding learning, memory and mood regulation.

Specifically, the researchers, who include a husband-and-wife team, found evidence of an epigenetic change called demethylation -- the loss of a methyl group from specific locations -- in the non-dividing brain cells' DNA, challenging the scientific dogma that even if the DNA in non-dividing adult neurons changes on occasion from methylated to demethylated state, it does so very infrequently.

"We provide definitive evidence suggesting that DNA demethylation happens in non-dividing neurons, and it happens on a large scale," says Hongjun Song, Ph.D., professor of neurology and neuroscience and director of the Stem Cell Program in the Institute for Cell Engineering of the Johns Hopkins University School of Medicine. "Scientists have previously underestimated how important this epigenetic mechanism can be in the adult brain, and the scope of change is dramatic."

DNA comprises the fixed chemical building blocks of each person or animal's genome, but the addition or removal of a methyl group at the specific location chemically alters DNA and regulates gene expression, enabling cells with the same genetic code to acquire and activate separate functions.

In previously published work, the same Hopkins researchers reported that electrical brain stimulation, such as that used in electroconvulsive therapy (ECT) for patients with drug resistant depression, resulted in increased brain cell growth in mice, due likely to changes in DNA methylation status.

This time, they again used electric shock to stimulate the brains of live mice. A few hours after administering the brain stimulation, the scientists analyzed two million of the same type of neurons from the brains of stimulated mice, focusing on what happens to one building block of DNA -- cytosine -- at 219,991 sites. These sites represented about one percent of all cytosines in the whole mouse genomes.

In collaboration with genomic biologist Yuan Gao, now at the Lieber Institute for Brain Development, the scientists used the latest DNA sequencing technology and compared neurons in mice with or without brain stimulation. About 1.4 percent of the cytosines measured showed rapid active demethylation or became newly methylated.

"It was mind-boggling to see that so many methylation sites -- thousands of sites -- had changed in status as a result of brain activity," Song says. "We used to think that the brain's epigenetic DNA methylation landscape was as stable as mountains and more recently realized that maybe it was a bit more subject to change, perhaps like trees occasionally bent in a storm. But now we show it is most of all like a river that reacts to storms of activity by moving and changing fast." The majority of the sites where the methylation status of the cytosine changed as a result of the brain activity were not in the expected areas of the genome that are traditionally believed to control gene expression, Song notes. Rather, they were in regions where cytosines are low in density, in genomic regions where the function of DNA methylation is not well understood.

Because DNA demethylation can occur passively during cell division, the scientists targeted radiation to the sections of mouse brains they were studying, permanently preventing passive cell division, and still found evidence of DNA demethylation. This confirms, they say, that the DNA methylation changes they measured occurred independently of cell division.

"Our finding opens up new opportunities to figure out if these epigenetic modifications are potential drug targets for treating depression and promote regeneration, for instance," says Guo-li Ming, M.D., Ph.D., professor of neurology and neuroscience.

This research was supported by the National Institutes of Health, a McKnight Scholar Award, the Brain and Behavior Research Foundation, the Adelson Medical Research Foundation, and the Johns Hopkins Brain Science Institute.

Authors of the paper from Johns Hopkins in addition to Song and Ming are Junjie U. Guo, Dengke K. Ma, Eric Ford, Mi-Hyeon Jang, Michael A Bonaguidi and Yuan Gao.

Other authors are Huan Mo and Hugh L. Eaves of the Virginia Commonwealth University; Madeleine P. Ball, Harvard Medical School; Jacob A Balazer, Proofpoint Inc.; Bin Xie, Lieber Institute for Brain Development; and Kun Zhang, University of California at San Diego.


Story Source:

The above story is based on materials provided by Johns Hopkins Medical Institutions. Note: Materials may be edited for content and length.


Journal Reference:

  1. Junjie U Guo, Dengke K Ma, Huan Mo, Madeleine P Ball, Mi-Hyeon Jang, Michael A Bonaguidi, Jacob A Balazer, Hugh L Eaves, Bin Xie, Eric Ford, Kun Zhang, Guo-li Ming, Yuan Gao, Hongjun Song. Neuronal activity modifies the DNA methylation landscape in the adult brain. Nature Neuroscience, 2011; 14 (10): 1345 DOI: 10.1038/nn.2900

Cite This Page:

Johns Hopkins Medical Institutions. "Scientists discover 'fickle' DNA changes in brain." ScienceDaily. ScienceDaily, 1 October 2011. <www.sciencedaily.com/releases/2011/09/110930195143.htm>.
Johns Hopkins Medical Institutions. (2011, October 1). Scientists discover 'fickle' DNA changes in brain. ScienceDaily. Retrieved April 21, 2014 from www.sciencedaily.com/releases/2011/09/110930195143.htm
Johns Hopkins Medical Institutions. "Scientists discover 'fickle' DNA changes in brain." ScienceDaily. www.sciencedaily.com/releases/2011/09/110930195143.htm (accessed April 21, 2014).

Share This



More Health & Medicine News

Monday, April 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Nine-Month-Old Baby Can't Open His Mouth

Nine-Month-Old Baby Can't Open His Mouth

Newsy (Apr. 19, 2014) Nine-month-old Wyatt Scott was born with a rare disorder called congenital trismus, which prevents him from opening his mouth. Video provided by Newsy
Powered by NewsLook.com
'Holy Grail' Of Weight Loss? New Find Could Be It

'Holy Grail' Of Weight Loss? New Find Could Be It

Newsy (Apr. 18, 2014) In a potential breakthrough for future obesity treatments, scientists have used MRI scans to pinpoint brown fat in a living adult for the first time. Video provided by Newsy
Powered by NewsLook.com
Little Progress Made In Fighting Food Poisoning, CDC Says

Little Progress Made In Fighting Food Poisoning, CDC Says

Newsy (Apr. 18, 2014) A new report shows rates of two foodborne infections increased in the U.S. in recent years, while salmonella actually dropped 9 percent. Video provided by Newsy
Powered by NewsLook.com
Scientists Create Stem Cells From Adult Skin Cells

Scientists Create Stem Cells From Adult Skin Cells

Newsy (Apr. 17, 2014) The breakthrough could mean a cure for some serious diseases and even the possibility of human cloning, but it's all still a way off. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins