CCTV.com - CNTV English - CCTV News

U.S. researchers complete first genome-wide mapping of DNA modification

07-23-2011 17:12 BJT

LOS ANGELES, July 22 (Xinhua) -- U.S. researchers have completed the first genome-wide mapping of a DNA modification called 5-hydroxymethylcytosine (5hmC) in embryonic stem cells.

The molecule is predominantly found in genes that are turned on, or active, according to the researchers from the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at University of California, Los Angeles.

The finding may prove to be important in controlling diseases like cancer, where the regulation of certain genes plays a role in disease development.

The researchers used genomics to define where in human embryonic stem cells the 5hmC was present.

Human embryonic stem cells were used because it had been shown previously that the molecule is abundant in those cells, as well as in brain cells, said lead researcher Steven E. Jacobsen, a professor of molecular, cell and developmental biology.

In the study, the researchers found that 5hmC was associated with genes and tended to be found on genes that were active. The study also revealed that 5hmC was present on a type of DNA regulatory element, called enhancers, which help control gene expression. In particular, 5hmC was present on enhancers that are crucial for defining the nature of the human embryonic stem cells.

The results suggest that 5hmC plays a role in the activation of genes. This is opposite of the role of the more well studied 5mC ( DNA methylation), which is involved in silencing genes. This relationship is in line with the view that 5hmC is created directly from 5mC.

"If we can understand the function of 5hmC, that will lead to greater understanding of how genes are turned on and off and that could lead to the development of methods for controlling gene regulation," Jacobsen said.

"Any way you can control genes will be hugely important for human disease and cancer. Cancer is generally a problem of genes being inappropriately turned off or mutated, like tumor suppressors genes, or genes that should be off getting switched on. "

5hmC is formed from the DNA base cytosine by adding a methyl group and then a hydroxy group. The molecule is important in epigenetics - the study of changes in gene expression caused by mechanisms other than changes in the DNA sequence - because the newly formed hydroxymethyl group on the cytosine can potentially switch a gene on and off, Jacobsen said.

The molecule 5hmC was only recently discovered, and its function has not been clearly understood, Jacobsen said. Until now, researchers didn't know where 5hmC was located within the genome.

The study appears in the July issue of the journal Genome Biology.

Editor:Zhang Pengfei |Source: Xinhua

Hot Videos view more

The celebrations are still continuing as the victorious coach, Joachim Loew, has been honored for his achievement in his hometown of Freiburg.
Germany coach Loew honored in hometown of Freiburg

Chinese men´s national team continued its preparations for next year´s Asian Cup, as they managed a one-all draw against visitors Jordan during a football friendly in Harbin, the capital city of Northeast China´s Heilongjiang Province.
China held to 1-1 draw by Jordan

The defending world champs came into the contest with a perfect 6-and-oh record, but they would be in for a tough first half before opening things up in the second.
USA beat Slovenia 119-76 in quarter-finals

Hot Stories more

UK authorities believe killer of James Foley is a British national

Across the UK the hunt is on for James Foley’s killer, who authorities believe is a British national. As Richard Bestic reports from London, Prime Minister David Cameron cut short his summer break to lead his government’s response.

Israeli war jets renews Gaza strike as truce talks stalled

Three Palestinians were killed and 40 others wounded in the intensive Israeli war jets´ airstrikes on the Gaza city on Tuesday night, shortly before an end of a 24-hour ceasefire in the Gaza Strip,

Missouri police arrest dozens after violent night

As the protests in the town of Ferguson, Missouri turned violent with police facing ´heavy gunfire´ from some ´criminal elements´, cops fired tear gas, stun grenades and arrested 31 demonstrators on Monday night.

Picture in news more

More Video News

Choose TV Program