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 Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

nachricht First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>