Featured Research

from universities, journals, and other organizations

A potential cause of autism? Key enzymes are found to have a 'profound effect' across dozens of genes linked to autism

Date:
August 28, 2013
Source:
University of North Carolina School of Medicine
Summary:
Problems with a key group of enzymes called topoisomerases can have profound effects on the genetic machinery behind brain development and potentially lead to autism spectrum disorder (ASD), according to new research. Scientists have described a finding that represents a significant advance in the hunt for environmental factors behind autism and lends new insights into the disorder’s genetic causes.

Topoisomerase inhibitors reduce the expression of long genes in neurons, including a remarkable number of genes implicated in Autism Spectrum Disorders -- 200 kb is four times longer than the average gene.
Credit: Concept: Mark Zylka. Illustration: Janet Iwasa.

Problems with a key group of enzymes called topoisomerases can have profound effects on the genetic machinery behind brain development and potentially lead to autism spectrum disorder (ASD), according to research announced today in the journal Nature. Scientists at the University of North Carolina School of Medicine have described a finding that represents a significant advance in the hunt for environmental factors behind autism and lends new insights into the disorder's genetic causes.

"Our study shows the magnitude of what can happen if topoisomerases are impaired," said senior study author Mark Zylka, PhD, associate professor in the Neuroscience Center and the Department of Cell Biology and Physiology at UNC. "Inhibiting these enzymes has the potential to profoundly affect neurodevelopment -- perhaps even more so than having a mutation in any one of the genes that have been linked to autism."

The study could have important implications for ASD detection and prevention.

"This could point to an environmental component to autism," said Zylka. "A temporary exposure to a topoisomerase inhibitor in utero has the potential to have a long-lasting effect on the brain, by affecting critical periods of brain development. "

This study could also explain why some people with mutations in topoisomerases develop autism and other neurodevelopmental disorders.

Topiosomerases are enzymes found in all human cells. Their main function is to untangle DNA when it becomes overwound, a common occurrence that can interfere with key biological processes.

Most of the known topoisomerase-inhibiting chemicals are used as chemotherapy drugs. Zylka said his team is searching for other compounds that have similar effects in nerve cells. "If there are additional compounds like this in the environment, then it becomes important to identify them," said Zylka. "That's really motivating us to move quickly to identify other drugs or environmental compounds that have similar effects -- so that pregnant women can avoid being exposed to these compounds."

Zylka and his colleagues stumbled upon the discovery quite by accident while studying topotecan, a topoisomerase-inhibiting drug that is used in chemotherapy. Investigating the drug's effects in mouse and human-derived nerve cells, they noticed that the drug tended to interfere with the proper functioning of genes that were exceptionally long -- composed of many DNA base pairs. The group then made the serendipitous connection that many autism-linked genes are extremely long.

"That's when we had the 'Eureka moment,'" said Zylka. "We realized that a lot of the genes that were suppressed were incredibly long autism genes."

Of the more than 300 genes that are linked to autism, nearly 50 were suppressed by topotecan. Suppressing that many genes across the board -- even to a small extent -- means a person who is exposed to a topoisomerase inhibitor during brain development could experience neurological effects equivalent to those seen in a person who gets ASD because of a single faulty gene.

The study's findings could also help lead to a unified theory of how autism-linked genes work. About 20 percent of such genes are connected to synapses -- the connections between brain cells. Another 20 percent are related to gene transcription -- the process of translating genetic information into biological functions. Zylka said this study bridges those two groups, because it shows that having problems transcribing long synapse genes could impair a person's ability to construct synapses.

"Our discovery has the potential to unite these two classes of genes -- synaptic genes and transcriptional regulators," said Zylka. "It could ultimately explain the biological mechanisms behind a large number of autism cases."

The study's coauthors include Benjamin Philpot (co-senior author), Terry Magnuson, Ian King, Chandri Yandava, Angela Mabb, Hsien-Sung Huang, Brandon Pearson, J. Mauro Calabrese, Joshua Starmer and Joel Parker from UNC and Jack S. Hsiao and Stormy Chamberlain of the University of Connecticut Health Center.


Story Source:

The above story is based on materials provided by University of North Carolina School of Medicine. Note: Materials may be edited for content and length.


Journal Reference:

  1. Ian F. King, Chandri N. Yandava, Angela M. Mabb, Jack S. Hsiao, Hsien-Sung Huang, Brandon L. Pearson, J. Mauro Calabrese, Joshua Starmer, Joel S. Parker, Terry Magnuson, Stormy J. Chamberlain, Benjamin D. Philpot, Mark J. Zylka. Topoisomerases facilitate transcription of long genes linked to autism. Nature, 2013; DOI: 10.1038/nature12504

Cite This Page:

University of North Carolina School of Medicine. "A potential cause of autism? Key enzymes are found to have a 'profound effect' across dozens of genes linked to autism." ScienceDaily. ScienceDaily, 28 August 2013. <www.sciencedaily.com/releases/2013/08/130828131841.htm>.
University of North Carolina School of Medicine. (2013, August 28). A potential cause of autism? Key enzymes are found to have a 'profound effect' across dozens of genes linked to autism. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2013/08/130828131841.htm
University of North Carolina School of Medicine. "A potential cause of autism? Key enzymes are found to have a 'profound effect' across dozens of genes linked to autism." ScienceDaily. www.sciencedaily.com/releases/2013/08/130828131841.htm (accessed July 24, 2014).

Share This




More Mind & Brain News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Painkiller Designed To Discourage Abuse: Will It Work?

New Painkiller Designed To Discourage Abuse: Will It Work?

Newsy (July 24, 2014) The FDA approved Targiniq ER on Wednesday, a painkiller designed to keep users from abusing it. Like any new medication, however, it has doubters. Video provided by Newsy
Powered by NewsLook.com
China's Ageing Millions Look Forward to Bleak Future

China's Ageing Millions Look Forward to Bleak Future

AFP (July 24, 2014) China's elderly population is expanding so quickly that children struggle to look after them, pushing them to do something unexpected in Chinese society- move their parents into a nursing home. Duration: 02:07 Video provided by AFP
Powered by NewsLook.com
Idaho Boy Helps Brother With Disabilities Complete Triathlon

Idaho Boy Helps Brother With Disabilities Complete Triathlon

Newsy (July 23, 2014) An 8-year-old boy helped his younger brother, who has a rare genetic condition that's confined him to a wheelchair, finish a triathlon. Video provided by Newsy
Powered by NewsLook.com
Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Newsy (July 22, 2014) The 83 new genetic markers could open dozens of new avenues for schizophrenia treatment research. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins