Featured Research

from universities, journals, and other organizations

Head Trauma Damages DNA Repair Mechanism

Date:
July 12, 1999
Source:
University Of Pennsylvania Medical Center
Summary:
Last year, researchers at the University of Pennsylvania Medical Center found that brain cells continue to die for weeks to months after sustaining injury. Now, these investigators have found that a cell's ability to detect damage to DNA in its nucleus is also impaired for months after an injury.

Last year, researchers at the University of Pennsylvania Medical Center found that brain cells continue to die for weeks to months after sustaining injury. Now, these investigators have found that a cell's ability to detect damage to DNA in its nucleus is also impaired for months after an injury. The DNA in human cells is assaulted everyday by all sorts of damaging agents -- ultraviolet radiation, chemicals, and heat, for example -- but normally the body has a vigilant surveillance system in place to detect damage and quickly repair it.

"This is the first paper to show that brain trauma alters the specific pathways for recognizing DNA damage and initiating the DNA repair process," says senior author Tracy K. McIntosh, PhD, professor of neurosurgery, bioengineering, and pharmacology and director of Penn's Head Injury Center. McIntosh and colleagues report their findings in the current issue of the Journal of Neurochemistry.

Using a model of experimental brain injury in rats, McIntosh and colleagues showed that the enzyme poly(ADP-ribose) polymerase (PARP), which repairs specific cuts in the DNA helix, is activated by brain cells as early as 30 minutes after an injury. But, at seven days post-injury, destruction of PARP becomes pronounced, which suggests that DNA repair is initiated in the acute post-injury phase, but subsequent DNA repair may be weakened. The researchers hypothesize that this might be due to cell-death-mediated degradation of PARP, which ultimately adversely affects the repair of damaged DNA.

Essentially, an injured cell's internal observation system for detecting damage breaks down and cellular repair crews are never called into action. "If the body can't detect that DNA has been fragmented, the repair mechanisms that we normally have in place can't do their job," says McIntosh. "So, all the efforts we're using to save cells after brain damage become useless, because if the DNA is damaged, the cell can't make proteins and will eventually die."

Calcium enters cells in massive amounts following injury, with devastating effects. As a result, harsh biochemicals called oxygen free radicals punch holes in the cell membrane, and intracellular proteases called calpains attack the cell's internal skeleton, both of which cause the cell to collapse. Immediately after trauma, various drugs are given to stop calcium entry.

But, this cascade of events occurs outside the nucleus, away from the genome. "If we go to great lengths to protect the cell and in the meantime the DNA is also damaged due to trauma, that cell is doomed and all of our heroic efforts will have been in vain," notes McIntosh.

PARP production may also be detrimental for the injured brain because its activation uses up an enormous amount of energy, draining much-needed biochemical fuel from tissue repair, which further contributes to cell death. McIntosh's lab is currently evaluating the energy-draining theory by pharmacologically inhibiting PARP in rodents.

Michelle LaPlaca, PhD, a former post-doctoral fellow in McIntosh's lab was lead author of the study. Penn colleagues Ramesh Raghupathi, PhD, assistant professor of neurosurgery, and Kathryn Saatman, PhD, research assistant professor of neurosurgery, also collaborated on this study. This research was supported by grants from the National Institutes of Health.


Story Source:

The above story is based on materials provided by University Of Pennsylvania Medical Center. Note: Materials may be edited for content and length.


Cite This Page:

University Of Pennsylvania Medical Center. "Head Trauma Damages DNA Repair Mechanism." ScienceDaily. ScienceDaily, 12 July 1999. <www.sciencedaily.com/releases/1999/07/990712081442.htm>.
University Of Pennsylvania Medical Center. (1999, July 12). Head Trauma Damages DNA Repair Mechanism. ScienceDaily. Retrieved August 22, 2014 from www.sciencedaily.com/releases/1999/07/990712081442.htm
University Of Pennsylvania Medical Center. "Head Trauma Damages DNA Repair Mechanism." ScienceDaily. www.sciencedaily.com/releases/1999/07/990712081442.htm (accessed August 22, 2014).

Share This




More Mind & Brain News

Friday, August 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Lost Brain Cells To Blame For Sleep Problems Among Seniors

Lost Brain Cells To Blame For Sleep Problems Among Seniors

Newsy (Aug. 21, 2014) According to a new study, elderly people might have trouble sleeping because of the loss of a certain group of neurons in the brain. Video provided by Newsy
Powered by NewsLook.com
Do More Wedding Guests Make A Happier Marriage?

Do More Wedding Guests Make A Happier Marriage?

Newsy (Aug. 20, 2014) A new study found couples who had at least 150 guests at their weddings were more likely to report being happy in their marriages. Video provided by Newsy
Powered by NewsLook.com
Charter Schools Alter Post-Katrina Landscape

Charter Schools Alter Post-Katrina Landscape

AP (Aug. 20, 2014) Nine years after Hurricane Katrina, charter schools are the new reality of public education in New Orleans. The state of Louisiana took over most of the city's public schools after the killer storm in 2005. (Aug. 20) Video provided by AP
Powered by NewsLook.com
Researcher Testing on-Field Concussion Scanners

Researcher Testing on-Field Concussion Scanners

AP (Aug. 19, 2014) Four Texas high school football programs are trying out an experimental system designed to diagnose concussions on the field. The technology is in response to growing concern over head trauma in America's most watched sport. (Aug. 19) Video provided by AP
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