Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Permanent Changes In Brain Genes May Not Be So Permanent After All

29.01.2014
In normal development, all cells turn off genes they don’t need, often by attaching a chemical methyl group to the DNA, a process called methylation.

Historically, scientists believed methyl groups could only stick to a particular DNA sequence: a cytosine followed by a guanine, called CpG. But in recent years, they have been found on other sequences, and so-called non-CpG methylation has been found in stem cells, and in neurons in the brain.

Now, a team of researchers at Johns Hopkins has discovered that non-CpG methylation occurs later and more dynamically in neurons than previously appreciated, and that it acts as a system of gene regulation, which can be independent of traditional CpG methylation.

In a study described in the January 28 issue of Nature Neuroscience, the Hopkins team describes this new gene control mechanism and how it may contribute to Rett Syndrome, a nervous system disorder affecting mostly girls that causes problems with movement and communication.

The team, led by Hongjun Song, Ph.D., professor of neurology and director of Johns Hopkins Medicine's Institute for Cell Engineering's Stem Cell Program, had found non-CpG methylation prevalent in neurons, a finding that surprised them, since this wasn’t found in any other cells besides stem cells.

By looking at what genes were being transcribed in neurons, he and his colleagues found that, like the form of methylation scientists had seen in stem cells, non-CpG methylation stops genes from being expressed. They also mapped the genome to find where non-CpG methylation happens, and found that it carves out its own niche, and are distributed in regions without CpG methlyation. "That was the first hint that maybe it can function independently of CpG methylation," Song says.

The new kind of methylation also seems to operate under different rules. Scientists have long thought methylation was final. Once a cytosine gets a methyl stuck to it, so the story went, that gene is shut off forever. "This became dogma," Song says. "Once cells become the right type, they don't change their identity or DNA methylation."

But non-CpG methylation seems to happen later, when the neuron is mature—and even after conventional wisdom said it was irreversible. The researchers learned this from an experiment in which they knocked out in adult mice the enzymes that attach methyl groups to DNA. They found the neurons still had just as much CpG methylation, but the non-CpG methylation dropped off. This suggests that non-CpG methylation is an active process, Song says, with methyl groups continually being taken off and put back on, adding to evidence that non-CpG methylation may play more of a role in managing operations in mature cells.

The researchers also found a way that non-CpG methylation is similar to CpG methylation in one important way: it's read by MeCP2, an enzyme long identified as a player in methylation.

That's significant because a mutation in MeCP2 causes Rett Syndrome, and understanding DNA methylation is key to understanding this syndrome. The disorder occurs, Song says, when working copies of the gene for MeCP2 are silenced during development.

Other authors on the paper include Junjie Guo, Yijing Su, Joo Heon Shin, Jaehoon Shin, Bin Xie, Chun Zhong, Shaohui Hu, Heng Zhu, Yuan Gao and Guo-li Ming, all of Johns Hopkins University;Hongda Li and Qiang Chang of the University of Wisconsin-Madison; and Thuc Le and Guoping Fan of University of California Los Angeles.

This research was supported by the National Institute of Neurological Disorders and Stroke(NS047344, NS048271 and NS072924), National Institute of Environmental Health Sciences (ES021957), the National Institute of Mental Health (MH087874), National Institute of Child Health and Human Development (HD06918, HD064743 and HD066560), the Simons Foundation Autism Research Initiative, NARSAD, the Maryland Stem Cell Research Fund (MSCRF) and the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation.

Nature Neuroscience article

Contact Information
Johns Hopkins Medicine
Media Relations and Public Affairs
Media Contacts: Vanessa McMains; 410-502-9410; vmcmain1@jhmi.edu
Catherine Kolf; 443-287-2251; ckolf@jhmi.edu

Vanessa McMains | Newswise
Further information:
http://www.jhmi.edu

More articles from Life Sciences:

nachricht Fruit fly studies shed light on adaptability of nerve cells
17.04.2015 | Deutsches Zentrum für Neurodegenerative Erkrankungen e.V. (DZNE)

nachricht Rare monkey photographed in Congo's newest national park, Ntokou-Pikounda
17.04.2015 | Wildlife Conservation Society

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Astronomers reveal supermassive black hole's intense magnetic field

Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a supermassive black hole in a distant galaxy

Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a...

Im Focus: A “pin ball machine” for atoms and photons

A team of physicists from MPQ, Caltech, and ICFO proposes the combination of nano-photonics with ultracold atoms for simulating quantum many-body systems and creating new states of matter.

Ultracold atoms in the so-called optical lattices, that are generated by crosswise superposition of laser beams, have been proven to be one of the most...

Im Focus: UV light robot to clean hospital rooms could help stop spread of 'superbugs'

Can a robot clean a hospital room just as well as a person?

According to new research out of the Texas A&M Health Science Center College of Medicine, that is indeed the case. Chetan Jinadatha, M.D., M.P.H., assistant...

Im Focus: Graphene pushes the speed limit of light-to-electricity conversion

Researchers from ICFO, MIT and UC Riverside have been able to develop a graphene-based photodetector capable of converting absorbed light into an electrical voltage at ultrafast timescales

The efficient conversion of light into electricity plays a crucial role in many technologies, ranging from cameras to solar cells.

Im Focus: Study shows novel pattern of electrical charge movement through DNA

Electrical charges not only move through wires, they also travel along lengths of DNA, the molecule of life. The property is known as charge transport.

In a new study appearing in the journal Nature Chemistry, authors, Limin Xiang, Julio Palma, Christopher Bruot and others at Arizona State University's...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

HHL's Entrepreneurship Conference on FinTech

13.04.2015 | Event News

World Conference On Regenerative Medicine 2015: Registration And Abstract Submission Now Open

25.03.2015 | Event News

University presidents from all over the world meet in Hamburg

19.03.2015 | Event News

 
Latest News

Engineer Improves Rechargeable Batteries with MoS2 Nano 'Sandwich'

17.04.2015 | Power and Electrical Engineering

Comparing Climate Models to Real World Shows Differences in Precipitation Intensity

17.04.2015 | Earth Sciences

A blueprint for clearing the skies of space debris

17.04.2015 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>