A study led by St. Jude Children's Research Hospital has discovered mutations in two genes that lead to the death of nerve cells in amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, and related degenerative diseases.
The same mutation occurred in both genes and led to the abnormal build-up of the proteins inside cells. These proteins play an essential role in normal RNA functioning and have also been linked to cancer, including the Ewing sarcoma, the second most common type of bone cancer in children and adolescents. The finding is the latest in a series of discoveries suggesting degenerative diseases and cancer may have common origins. RNA is the molecule that directs protein assembly based on instructions carried in DNA.
The study also adds to evidence that seemingly unrelated neurodegenerative diseases may involve similar defects in RNA metabolism. Researchers linked the problems to a specific region of the mutated proteins whose normal function was unclear. The study was published today in the advanced online edition of the scientific journal Nature.
"I hope this study helps to build the foundation for desperately needed treatments for ALS and perhaps a broad range of diseases caused by abnormal RNA metabolism," said J. Paul Taylor, M.D., Ph.D., an associate member of the St. Jude Department of Developmental Neurobiology and senior author of the study. Taylor and James Shorter, Ph.D., an assistant professor in the biochemistry and biophysics department at the University of Pennsylvania's Perelman School of Medicine, are the study's corresponding authors.
Each year approximately 5,600 people in the U.S. are found to have ALS. The disease is nearly always fatal, often within five years. Patients suffer muscle wasting and paralysis that affects their limbs and trunk as well as their ability to talk, swallow and breathe. There is no cure.
For this project, St. Jude sequenced just the portion of the genome called the exome, which carries instructions for making proteins. Researchers sequenced the exomes of two families affected by rare inherited degenerative disorders that target cells in the muscle, bone and brain. Neither family carried mutations previously tied to ALS or related diseases. The project built on the infrastructure developed by the St. Jude Children's Research Hospital -- Washington University Pediatric Cancer Genome Project, which played an important role in finding the mutations.
Researchers found the families carried a single, previously unknown mutation in a pair of RNA-binding proteins named hnRNPA2B1 and hnRNPA1. The proteins both bind RNA and help regulate its function. When researchers checked for the same mutations in 517 ALS patients they found hnRNPA1 protein mutated in two patients. One patient had the inherited form of ALS. The other ALS patient had no family history of the disease.
The new mutations occurred in a region of the proteins Taylor refers to as a prion-like domain because it has similarities with yeast proteins called prions. Prions are proteins that can alternate between shapes as needed for different functions. "Until recently we did not know these domains existed in humans and now we realize that hundreds of human proteins have them," Taylor said. "We're only beginning to understand their function in human cells."
Researchers showed the prion-like domains are responsible for the shape change that occurs when these proteins convert into slender threads called fibrils. The mutations accelerate fibril formation and recruit normal proteins to form fibrils. This phenomenon called propagation may explain how ALS and related diseases spread throughout the nervous system.
Taylor speculated that the normal function of prion-like domains is to assemble RNAs into temporary structures called granules, which are part of the cell's normal protein production machinery. Granules are normally short lived, and the RNA-binding proteins involved in their formation are recycled. But in cells with hnRNPA2B1 or hnRNPA1 mutation, RNA granules accumulated in the cytoplasm instead of being disassembled. "That's bad news for RNA regulation, which is bad news for those cells," Taylor said.
The study has several important implications, Taylor said. Recognition that the mutations adversely impact regulation of RNA could lead to targeted therapy to correct the problem. The mutation's location in the prion-like domain might also prove significant. Although the mutations in hnRNPA2B1 or hnRNPA1 appear to be rare, hundreds of other RNA-binding proteins have prion-like domains. Taylor said patients with unexplained neurodegenerative diseases may have mutations in these proteins.
The study's first authors are Hong Joo Kim, Nam Chul Kim, Yong-Dong Wang and Jennifer Moore, all of St. Jude; and Emily Scarborough and Zamia Diaz, both of the University of Pennsylvania. The other authors are Kyle MacLea and Eric Ross, both of Colorado State University; Brian Freibaum, Songqing Li, Anderson Kanagaraj and Robert Carter, all of St. Jude; Amandine Molliex, formerly of St. Jude; Kevin Boylan, Aleksandra Wojtas and Rosa Rademakers, all of the Mayo Clinic, Jacksonville, Fla.; Jack Pinkus and Steven Greenberg, both of Brigham and Women's Hospital and Harvard Medical School; John Trojanowski, Bradley Smith, Yun Li and Alice Flynn Ford, all of the University of Pennsylvania; Bryan Traynor, of the National Institute of Aging, National Institutes of Health, Bethesda, Md.; Simon Topp, Athina-Soragia Gkazi, Jack Miller and Christopher Shaw, all of the Institute of Psychiatry, London; Michael Kottlors and Janbernd Kirschner, both of University Children's Hospital Freiburg, Germany; Alan Pestronk and Conrad Weihl, both of the Washington University School of Medicine, St. Louis; Aaron Gitler, Stanford University School of Medicine; Michael Benatar, University of Miami Miller School of Medicine; Oliver King, Boston Biomedical Research Institute, Watertown, Mass.; and Virginia Kimonis, University of California-Irvine.
The research was supported in part by the Packard Foundation, by grants (NS053825, AG032953, DP2OD002177 and NS067354) from the National Institutes of Health, the ALS Association, the Ellison Medical Foundation, a grant (MCB-1023771) from the National Science Foundation and ALSAC.
St. Jude Children's Research Hospital
St. Jude Children's Research Hospital is internationally recognized for its pioneering research and treatment of children with cancer and other life-threatening diseases. The hospital's research has helped push overall survival rates for childhood cancer from less than 20 percent when the institution opened to almost 80 percent today. It is the first and only National Cancer Institute-designated Comprehensive Cancer Center devoted solely to children, and no family ever pays St. Jude for anything. For more information, visit www.stjude.org. Follow us on Twitter @StJudeResearch.
Summer Freeman | EurekAlert!
A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)
CWRU researchers find a chemical solution to shrink digital data storage
22.06.2017 | Case Western Reserve University
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.
New Manufacturing Technologies for New Products
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
22.06.2017 | Life Sciences
22.06.2017 | Materials Sciences
22.06.2017 | Materials Sciences