Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Patterns of new DNA letter in brain suggest distinct function

31.10.2011
Vocabulary of epigenetics expanding

In 2009, the DNA alphabet expanded. Scientists discovered that an extra letter or "sixth nucleotide" was surprisingly abundant in DNA from stem cells and brain cells.

Now, researchers at Emory University School of Medicine have mapped the patterns formed by that letter in the brains of mice, observing how its pattern of distribution in the genome changes during development and aging.

Those patterns, stable or dynamic depending on the gene, suggest that 5-hydroxymethylcytosine (5-hmC) has its own distinct functions, which still need to be fully brought to light.

"Our data tells us that 5-hmC is not just an intermediate state," says senior author Peng Jin, PhD, associate professor of human genetics at Emory University School of Medicine. "It looks like it has specific functions in stem cells and brain. 5-hmC may poise a gene to be turned on after being repressed."

The results were published online Sunday by the journal Nature Neuroscience. The paper is the first report on how the patterns of 5-hmC's distribution change in mouse brain during development, and also contains data on 5-hmC in DNA samples from human brain.

Postdoctoral fellow Keith Szulwach and instructor Xuekun Li are co-first authors, and collaborators from the University of Chicago and the University of Wisconsin-Madison contributed to the paper.

5-hydroxymethylcytosine (5-hmC) is an epigenetic modification of cytosine, one of the four bases or "letters" making up DNA. Epigenetic modifications are changes in the way genes are turned on or off, but are not part of the underlying DNA sequence. 5-hmC resembles 5-methylcytosine (5-mC), another modified DNA base that scientists have been studying for decades. Until recently, chemical techniques did not allow scientists to tell the difference between them.

In contrast to 5-mC, 5-hmC appears to be enriched on active genes, especially in brain cells. 5-mC is generally found on genes that are turned off or on repetitive "junk" regions of the genome. When stem cells change into the cells that make up blood, muscle or brain, 5-mC helps shut off genes that aren't supposed to be turned on. Changes in 5-mC's distribution also underpin a healthy cell's transformation into a cancer cell.

It looks like 5-hmC can only appear on DNA where 5-mC already was present. This could be a clue that 5-hmC could be a transitory sign that the cell is going to remove a 5-mC mark. Jin says the patterns his team sees tell a different story, at least for some genes. On those genes, the level of 5-hmC is stably maintained and increases with age.

The Emory team used a method for chemically labeling 5-hmC they developed in cooperation with scientists at the University of Chicago. They find that 5-hmC is ten times more abundant in brain than in stem cells, and it is found more in the body of some genes, compared to stem cells.

In addition, the researchers found a relative lack of 5-hmC on X chromosomes in both males and females. That result is a surprise, Jin says, because it was already known that the X chromosome is subject to a special form of regulation in females only. Males have one X chromosome and females have two, and in female cells one of the X chromosomes is inactivated.

Jin's team is beginning to map how 5-hmC changes in neurological disorders, including Rett syndrome and autism, and refining techniques for detecting 5-hmC in DNA at high resolution.

The research was supported by the National Institutes of Health, the Simons Foundation and the Emory Genetics Discovery Initiative.

Reference: K.E. Szulwach et al 5-hydroxymethylcytosine–mediated epigenetic dynamics during postnatal neurodevelopment and aging. Nature Neuro. (2011).

Writer: Quinn Eastman

The Robert W. Woodruff Health Sciences Center of Emory University is an academic health science and service center focused on missions of teaching, research, health care and public service.

Learn more about Emory's health sciences:
Blog: http://emoryhealthblog.com
Twitter: @emoryhealthsci
Web: http://emoryhealthsciences.org

Holly Korschun | EurekAlert!
Further information:
http://www.emory.edu

More articles from Life Sciences:

nachricht 3D technology lets us look into the distant past
20.05.2019 | Eberhard Karls Universität Tübingen

nachricht Dangerous pathogens use this sophisticated machinery to infect hosts
20.05.2019 | California Institute of Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

Im Focus: A step towards probabilistic computing

Working group led by physicist Professor Ulrich Nowak at the University of Konstanz, in collaboration with a team of physicists from Johannes Gutenberg University Mainz, demonstrates how skyrmions can be used for the computer concepts of the future

When it comes to performing a calculation destined to arrive at an exact result, humans are hopelessly inferior to the computer. In other areas, humans are...

Im Focus: Recording embryonic development

Scientists develop a molecular recording tool that enables in vivo lineage tracing of embryonic cells

The beginning of new life starts with a fascinating process: A single cell gives rise to progenitor cells that eventually differentiate into the three germ...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Cement as a climate killer: Using industrial residues to produce carbon neutral alternatives

20.05.2019 | Materials Sciences

When bees are freezing

20.05.2019 | Life Sciences

Machine learning speeds modeling of experiments aimed at capturing fusion energy on Earth

20.05.2019 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>