Featured Research

from universities, journals, and other organizations

Human genes transplanted into zebrafish: Helps identify genes related to autism, schizophrenia and obesity

Date:
May 16, 2012
Source:
Duke University Medical Center
Summary:
Researchers have transplanted a set of human genes into a zebrafish and then used it to identify genes responsible for head size at birth. This finding also is related to some cases of autism and possibly schizophrenia and childhood obesity.

Here are images of live zebrafish that were studied for genetics and head size to give insight into human head size. The top fish does not have the gene KCTD13 and its head size and brain size are larger; the middle fish is normal; the fish on the bottom expresses too much of the gene and has the smallest head and brain size.
Credit: Christelle Golzio, Duke Center for Human Disease Modeling and Duke Department of Cell Biology

What can a fish tell us about human brain development? Researchers at Duke University Medical Center transplanted a set of human genes into a zebrafish and then used it to identify genes responsible for head size at birth.

Researchers at Duke University Medical Center transplanted a set of human genes into a zebrafish and then used it to identify genes responsible for head size at birth.

Head size in human babies is a feature that is related to autism, a condition that recent figures have shown to be more common than previously reported, 1 in 88 children in a March 2012 study. Head size is also a feature of other major neurological disorders, such as schizophrenia.

"In medical research, we need to dissect events in biology so we can understand the precise mechanisms that give rise to neurodevelopmental traits," said senior author Nicholas Katsanis, Ph.D., Jean and George Brumley Jr., MD, Professor of Developmental Biology, and Professor of Pediatrics and Cell Biology. "We need expert scientists to work side by side with clinicians who see such anatomic and other problems in patients, if we are to effectively solve many of our medical problems."

The study was published online in Nature journal on May 16.

Katsanis knew that a region on chromosome 16 was one of the largest genetic contributors to autism and schizophrenia, but a conversation at a European medical meeting pointed him to information that changes within that same region of the genome also were related to changes in a newborn's head size.

The problem was difficult to address because the region had large deletions and duplications in DNA, which are the most common mutational mechanisms in humans. "Interpretation is harrowingly hard," said Katsanis, who is also director of the Duke Center for Human Disease Modeling.

The reason is that a duplication of DNA or missing DNA usually involves several genes. "It is very difficult to go from 'here is a region with many genes, sometimes over 50' to 'these are the genes that are driving this pathology,'" Katsanis said.

"There was a light bulb moment," Katsanis said. "The area of the genome we were exploring gave rise to reciprocal (opposite) defects in terms of brain cell growth, so we realized that overexpressing a gene in question might give one phenotype -- a smaller head, while shutting down the same gene might yield the other, a larger head."

The researchers transplanted a common duplication area of human chromosome 16 known to contain 29 genes into zebrafish embryos and then systematically turned up the activity of each transplanted human gene to find which might cause a small head (microcephaly) in the fish. They then suppressed the same gene set and asked whether any of them caused the reciprocal defect: larger heads (macrocephaly).

The researchers knew that deletion of the region that contained these 29 genes occurred in 1.7% of children with autism.

It took the team a few months to dissect such a "copy number variant" -- an alteration of the genome that results in an abnormal number of one or more sections of chromosomal DNA.

"Now we can go from a genetic finding that is dosage-sensitive and start asking reasonable questions about this gene as it pertains to neurocognitive traits, which is a big leap," Katsanis said. Neurocognitive refers to the ability to think, concentrate, reason, remember, process information, learn, understand and speak.

Many human conditions have anatomical features that are also related to genetics, he said. "There are major limitations in studying autistic or schizophrenic behavior in zebrafish, but we can measure head size, jaw size, or facial abnormalities."

The single gene in question, KCTD13, is responsible for driving head size in zebrafish by regulating the creation and destruction of new neurons (brain cells). This discovery let the team focus on the analogous gene in humans. "This gene contributes to autism cases, and probably is associated with schizophrenia and also childhood obesity," Katsanis said.

Once the gene has been uncovered, researchers can examine the protein it produces. "Once you have the protein, you can start asking valuable functional questions and learning what the gene does in the animal or human," Katsanis said.

Copy number variants, such as the ones this team found on chromosome 16, are now thought to be one of the most common sources of genetic mutations. Hundreds, if not thousands, of such chromosomal deletions and duplications have been found in patients with a broad range of clinical problems, particularly neurodevelopmental disorders.

"Now we may have an efficient tool for dissecting them, which gives us the ability to improve both diagnosis and understanding of disease mechanisms," Katsanis said.

The current study suggests that KCTD13 is a major contributor to some cases of autism, but also points to the synergistic action of this gene with two other genes in the region, named MVP and MAPK3, Katsanis said.

Other authors include lead author Christelle Golzio, Jason Willer and Edwin Oh of the Duke Center for Human Disease Modeling and Department of Cell Biology; Mike Talkowski, Mei Sun and Jim Guzella from the Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital in Boston; Sebastien Jacquemont, Alexandre Reymond and Jacques Beckmann from the Service de Génétique Médicale, Centre Hospitalier Universitaire Vaudois, in Lausanne, Switzerland; and Yu Taniguchi, Akira Sawa and Atsushi Kamiya from the Department of Psychiatry, Johns Hopkins University School of Medicine in Baltimore.

Funding is from a Silvio O. Conte Center grant from the National Institute of Mental Health (NIMH), National Institutes of Health grants, the Simons Foundation, the Autism Consortium of Boston, the Leenaards Foundation Prize, the Swiss National Science Foundation, a National Science Foundation Sinergia grant, an NIMH National Research Service Award, and an academic study award from the University of Lausanne.


Story Source:

The above story is based on materials provided by Duke University Medical Center. Note: Materials may be edited for content and length.


Journal Reference:

  1. Christelle Golzio, Jason Willer, Michael E. Talkowski, Edwin C. Oh, Yu Taniguchi, Sébastien Jacquemont, Alexandre Reymond, Mei Sun, Akira Sawa, James F. Gusella, Atsushi Kamiya, Jacques S. Beckmann, Nicholas Katsanis. KCTD13 is a major driver of mirrored neuroanatomical phenotypes of the 16p11.2 copy number variant. Nature, 2012; 485 (7398): 363 DOI: 10.1038/nature11091

Cite This Page:

Duke University Medical Center. "Human genes transplanted into zebrafish: Helps identify genes related to autism, schizophrenia and obesity." ScienceDaily. ScienceDaily, 16 May 2012. <www.sciencedaily.com/releases/2012/05/120516140012.htm>.
Duke University Medical Center. (2012, May 16). Human genes transplanted into zebrafish: Helps identify genes related to autism, schizophrenia and obesity. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2012/05/120516140012.htm
Duke University Medical Center. "Human genes transplanted into zebrafish: Helps identify genes related to autism, schizophrenia and obesity." ScienceDaily. www.sciencedaily.com/releases/2012/05/120516140012.htm (accessed July 28, 2014).

Share This




More Health & Medicine News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

$15B Deal on Vets' Health Care Reached

$15B Deal on Vets' Health Care Reached

AP (July 28, 2014) — A bipartisan deal to improve veterans health care would authorize at least $15 billion in emergency spending to fix a veterans program scandalized by long patient wait times and falsified records. (July 28) Video provided by AP
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) — Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
West Africa Gripped by Deadly Ebola Outbreak

West Africa Gripped by Deadly Ebola Outbreak

AFP (July 28, 2014) — The worst-ever outbreak of the deadly Ebola epidemic grips west Africa, killing hundreds. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) — A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. 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