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 Single-stranded DNA and RNA origami go live
15.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

nachricht New antbird species discovered in Peru by LSU ornithologists
15.12.2017 | Louisiana State University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>