Genetics researchers have identified a key gene that, when mutated, causes the rare multisystem disorder Cornelia deLange syndrome (CdLS). By revealing how mutations in the HDAC8 gene disrupt the biology of proteins that control both gene expression and cell division, the research sheds light on this disease, which causes intellectual disability, limb deformations and other disabilities resulting from impairments in early development.
"As we better understand how CdLS operates at the level of cell biology, we will be better able to define strategies for devising treatments for CdLS, and possibly for related disorders," said study leader Matthew A. Deardorff, M.D., Ph.D., a pediatric genetics clinician and scientist at The Children's Hospital of Philadelphia. Deardorff also is in the Perelman School of Medicine at the University of Pennsylvania.
Deardorff and co-corresponding author Katsuhiko Shirahige, Ph.D., of the Research Center for Epigenetic Disease at the University of Tokyo, published their study online today in Nature.
The current findings add to previous discoveries by researchers at The Children's Hospital of Philadelphia. A group led by Ian Krantz, M.D., and Laird Jackson, M.D., announced in 2004 that mutations in the NIPBL gene are the primary cause of CdLS, accounting for roughly 60 percent of the "classical" cases of the disease. In 2007, Deardorff joined them to describe mutations in two additional genes, SMC1A and SMC3. First described in 1933, CdLS affects an estimated 1 in 10,000 children.
The CdLS research team at Children's Hospital has focused on the cohesin complex, a group of proteins that form a bracelet-like structure that encircles pairs of chromosomes, called sister chromatids. "Cohesin has two roles," said Deardorff. "It keeps sister chromatids together during cell division, and it allows normal transcription—the transmission of information from DNA to RNA."
Deardorff added that mutations that perturb normal cohesin function can interfere with normal human development. Such is the case in CdLS, which exemplifies a newly recognized class of diseases called cohesinopathies.
In the current study, the scientists investigated both acetylation—how an acetyl molecule is attached to part of the cohesin complex¬—and deactylation, the removal of that molecule. Normally, deactylation helps recycle cohesin to make it available during successive rounds of cell division. The study team found that mutations in the HDAC8 gene threw off normal cellular recycling of cohesin.
Mutations in the gene cause loss of HDAC8 protein activity, and consequently decrease the amount of "recharged" cohesin available to properly regulate gene transcription. This, in turn, the researchers suggest, impairs normal embryonic development and gives rise to CdLS.
The researchers showed in cell cultures that mutations in HDAC8 lead to a decrease in cohesin binding to genes, similar to that seen for cells deficient in the NIPBL gene. They also identified HDAC8 mutations in approximately 5 percent of patients with CdLS.
Because mothers of children with CdLS may carry mutations in the HDAC8 gene, identifying these mutations will be very useful in accurately counseling families of their recurrence risk—the likelihood of having a subsequent child with CdLS.
Furthermore, added Deardorff, by providing biological details of the underlying defect in CdLS, the current research suggests future approaches to treating the genetic disease. "By concentrating downstream on the biological pathway in the cohesin cycle rather than focusing on the defective gene, we may be able to eventually screen for small-molecule drugs that could be used to intervene in CdLS."
Deardorff and colleagues will continue investigate CdLS and possible therapies. Last month, the Doris Duke Charitable Foundation chose Deardorff to receive a Clinical Scientist Development Award. This three-year award, totaling $486,000, is directed to further studies of cohesin abnormalities in human disease. Deardorff is a member of Children's Hospital's Center for Cornelia deLange Syndrome and Related Diagnoses, one of the world's leading programs in studying and treating CdLS.
Financial support for this study came from the National Institutes of Health (grants HD055488, GM49758, and HD052860), the U.S.A. Cornelia deLange Syndrome Foundation, institutional funding from The Children's Hospital of Philadelphia, intramural funding from the University of Lubeck, and the Research Program of Innovative Cell Biology by Innovative Technology. Co-authors with Deardorff and Shirahige included researchers from the United States, Japan, Canada, France, Belgium, Germany, Greece and Denmark.
"HDAC8 mutations in Cornelia deLange Syndrome affect the cohesin acetylation cycle," Nature, advance online publication Aug. 12, 2012. http://dx.doi:10.1038/nature11316
About The Children's Hospital of Philadelphia: The Children's Hospital of Philadelphia was founded in 1855 as the nation's first pediatric hospital. Through its long-standing commitment to providing exceptional patient care, training new generations of pediatric healthcare professionals and pioneering major research initiatives, Children's Hospital has fostered many discoveries that have benefited children worldwide. Its pediatric research program is among the largest in the country, ranking third in National Institutes of Health funding. In addition, its unique family-centered care and public service programs have brought the 516-bed hospital recognition as a leading advocate for children and adolescents. For more information, visit http://www.chop.edu.
John Ascenzi | EurekAlert!
Atomic-level motion may drive bacteria's ability to evade immune system defenses
24.04.2017 | Indiana University
Two-dimensional melting of hard spheres experimentally unravelled after 60 years
24.04.2017 | University of Oxford
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences