Featured Research

from universities, journals, and other organizations

Jumping Genes Can Knock Out DNA; Alter Human Genome

Date:
August 9, 2002
Source:
University Of Michigan Health System
Summary:
Results of a new University of Michigan study suggest that junk DNA – dismissed by many scientists as mere strings of meaningless genetic code – could have a darker side.

ANN ARBOR, MI – Results of a new University of Michigan study suggest that junk DNA – dismissed by many scientists as mere strings of meaningless genetic code – could have a darker side.

Related Articles


In a paper published in the Aug. 9 issue of Cell, scientists from the U-M Medical School report that, in cultured human cancer cells, segments of junk DNA called LINE-1 elements can delete DNA when they jump to a new location – possibly knocking out genes or creating devastating mutations in the process.

"The value of this study is the unexpected knowledge that LINE-1 elements have the potential to cause broad-spectrum mutations in individual tumor cells," says John V. Moran, Ph.D., an assistant professor of human genetics and internal medicine in the U-M Medical School.

Transposable LINE-1 or L1 elements make up 17 percent of human DNA, according to Moran, who developed the first assay to identify mobile L1s in the human and mouse genome. L1s "reproduce" by using RNA and a process called reverse transcription to make complementary DNA copies of themselves, as they integrate into other DNA sequences.

"Of 37 transposable events in our study, four resulted in deletions of genetic material," says Nicolas Gilbert, Ph.D., a U-M post-doctoral fellow in human genetics. "One of the deletions was more than 24 Kb in length [24,000 individual units of DNA called nucleotides] and potentially as large as 71 Kb. That's roughly equivalent to the size of BRCA1, a well-known gene that helps prevent the development of breast cancer."

"In cultured cells, we know that L1s can add to the genome by increasing its size, and now we've learned that they can decrease genome size by deleting genetic material," says Sheila Lutz-Prigge, a U-M research associate and co-author of the study. "But we have no control over the size or location of the deletion, and we don't yet know how often it occurs in humans."

Moran and his research team are part of a small group of scientists who study L1s in the human genome. "My personal feeling is that L1s built our genome and have continued to co-evolve with us for millions of years in sort of a host-parasite relationship," Moran says. "The more we learn about L1s, the more we'll learn about the evolution of the human genome."

When the project began, Gilbert and Lutz-Prigge were simply looking for a faster, more efficient way to figure out where L1s land when they jump and what changes L1s make in the original DNA sequence. Instead of using time-consuming, traditional molecular cloning techniques, they developed a new plasmid cassette technology and used E. coli bacteria to churn out multiple copies of DNA at the insertion site.

"Before Nico and Sheila developed this technique, we could jump L1s into cells, but we could never get them out efficiently," Moran explains. "Now we can see where L1s integrate and what they change. Access to the draft human genome lets us isolate the original site prior to L1 integration, and compare it with the post-integration sequence. We have gone from characterizing four events over a six-year period to about 50 events within the last 18 months."

Moran says one of the more intriguing results of the study is that L1s use different mechanisms to create new breaks, or take advantage of existing breaks, in DNA. He suspects L1s interact in multiple ways with host enzymes in the cell.

"The L1 is always the same, no matter what cell it's in, so if you end up with different rearrangements, that implies interaction between host factors and the L1 retrotransposition machinery," he says. "The more we study L1s, the more we realize how little we know about them. In biology, the stories are always simple until somebody delves deeper into them."

The research project was supported by the W.M. Keck Foundation, the National Institutes of Health, the March of Dimes, and the U-M Comprehensive Cancer Center.


Story Source:

The above story is based on materials provided by University Of Michigan Health System. Note: Materials may be edited for content and length.


Cite This Page:

University Of Michigan Health System. "Jumping Genes Can Knock Out DNA; Alter Human Genome." ScienceDaily. ScienceDaily, 9 August 2002. <www.sciencedaily.com/releases/2002/08/020809071852.htm>.
University Of Michigan Health System. (2002, August 9). Jumping Genes Can Knock Out DNA; Alter Human Genome. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2002/08/020809071852.htm
University Of Michigan Health System. "Jumping Genes Can Knock Out DNA; Alter Human Genome." ScienceDaily. www.sciencedaily.com/releases/2002/08/020809071852.htm (accessed October 25, 2014).

Share This



More Health & Medicine News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Texas Nurse Nina Pham Cured of Ebola

Texas Nurse Nina Pham Cured of Ebola

AFP (Oct. 25, 2014) — An American nurse who contracted Ebola while caring for a Liberian patient in Texas has been declared free of the virus and will leave the hospital. Duration: 01:01 Video provided by AFP
Powered by NewsLook.com
IKEA Desk Converts From Standing to Sitting With One Button

IKEA Desk Converts From Standing to Sitting With One Button

Buzz60 (Oct. 24, 2014) — IKEA is out with a new convertible desk that can convert from a sitting desk to a standing one with just the push of a button. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Ebola Protective Suits Being Made in China

Ebola Protective Suits Being Made in China

AFP (Oct. 24, 2014) — A factory in China is busy making Ebola protective suits for healthcare workers and others fighting the spread of the virus. Duration: 00:38 Video provided by AFP
Powered by NewsLook.com
WHO: Millions of Ebola Vaccine Doses by 2015

WHO: Millions of Ebola Vaccine Doses by 2015

AP (Oct. 24, 2014) — The World Health Organization said on Friday that millions of doses of two experimental Ebola vaccines could be ready for use in 2015 and five more experimental vaccines would start being tested in March. (Oct. 24) 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:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

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