Researchers have linked newly discovered gene mutations to some cases of the progressive fatal neurological disease amyotrophic lateral sclerosis – ALS, also known as Lou Gehrig's disease. Shedding light on how ALS destroys the cells and leads to paralysis, the researchers found that mutations in this gene affect the structure and growth of nerve cells.
ALS attacks motor neurons, the nerve cells responsible for controlling muscles. People with ALS experience such early symptoms as limb weakness or swallowing difficulties. In most people, the disease leads to death three to five years after symptoms develop, usually as a result of respiratory failure.
Scientists at the University of Massachusetts Medical School, Worcester, collaborated with international ALS researchers to search for gene mutations in two large families with an inherited form of ALS. The researchers used a technique to decode only the protein-encoding portions of DNA, known as the exome, allowing an efficient yet thorough search of the DNA regions most likely to contain disease-causing mutations. This deep sequencing of the exome led to the identification of several different mutations in the gene for profilin (PFN1) which were present only in the family members that developed ALS. Further investigations of 272 other familial ALS cases across the world showed that profilin mutations were also found in a small subset (about 1 to 2 percent) of the familial ALS cases studied.
The protein profilin is a key part of the creation and remodeling of a nerve cell's scaffolding or cytoskeleton. In fly models, disrupting profilin stunts the growth of axons – the long cell projections used to relay signals from one neuron to the next or from motor neurons to muscle cells. After identifying the PFN1 mutations in ALS patients, the researchers demonstrated that these mutations inhibited axon growth in laboratory-grown motor neurons as well. They also found that mutant profilin accumulated in clumps in neural cells, as has been seen for other abnormal proteins associated with ALS, Parkinson's and Alzheimer's. Neural cells with PFN1 mutations also contained clumps of a protein known as TDP-43. Clumps of abnormal TDP-43 are found in most cases of ALS, further linking profilin to known ALS mechanisms.
John Landers, Ph.D., associate professor of neurology at the University of Massachusetts Medical School, described how studying ALS in large families is challenging. "ALS is a late-onset, rapidly progressive disease. Unless you've been following a family for decades, it is hard to get DNA samples to study," Dr. Landers said. "We were very fortunate to obtain the DNA samples with the help of our research collaborators and the affected families."
Over a dozen genes have been linked to ALS, and these findings support existing studies which suggest that cell cytoskeleton disruptions play a major role in ALS and other motor neuron diseases. Motor neurons are large cells with long axons that connect to muscle, and cytoskeleton proteins are especially important in the transport of proteins along the axon to the remote parts of the neuron. This information could be useful in developing strategies for detection and treatment of ALS.
"In all of the causative genes that we identify, we look for common pathways," Dr. Landers said. "Every time we are able to identify a new gene, we have another piece of the puzzle. Each one of these genes helps us to understand what's going on. The more of these we can find, the more we're going to know about what's going wrong in ALS."
Familial ALS accounts for 10 percent of all ALS cases, but the majority of ALS cases are sporadic, where the cause is unknown. Even though this new mutation is linked to familial ALS, it reveals information about the mechanisms underlying motor neuron degeneration in general, and also may have broader implications for understanding sporadic ALS.
"This discovery is highly significant and opens a new avenue of research," commented Amelie Gubitz, Ph.D., program director at the National Institute of Neurological Disorders and Stroke (NINDS), which funded the research. "There is growing evidence that ALS may be caused by a variety of cellular defects, and that it is a not a disorder with a single origin. Whether and where these disease pathways converge is an active area of research with important implications for therapy development."
This research was published online today by Nature. Scientists from research institutions in several countries contributed to the paper. In the United States, researchers from the University of Massachusetts Medical School, Emory University of Medicine, Atlanta, and Duke University School of Medicine, Durham, N. C., contributed to the study. In Italy, researchers from the University of Milan, the Institute of Hospitalization, Care and Scientific Research and the University of Pisa contributed to the study. In Israel, researchers from Tel Aviv Sourasky Medical Center contributed to the study. Additionally, researchers from the University Medical Centre Utrecht in the Netherlands, University of Guelph in Canada, and the Salpetriere Hospital in Paris contributed to the study.
The work was supported by grants from the NINDS, funded in part through the Recovery Act (NS065847, NS050557, NS070342). It was also supported by the Muscular Dystrophy Association, Agency of Research for Amyotrophic Lateral Sclerosis (AriSLA), SMA Europe, ALS Therapy Alliance, Project ALS, Partners in ALS Research, the Angel Fund, the Pierre L. de Bourgknecht ALS Research Foundation, the Al-Athel ALS Research Foundation, the ALS Family Charitable Foundation and a donation from Francesco Caleffi.
Reference: Wu, C-H., et al. "Mutations in the profilin 1 gene cause familial amyotrophic lateral sclerosis" Nature, published online July 15, 2012.
For more information about ALS, visit: http://www.ninds.nih.gov/ALS
NINDS (http://www.ninds.nih.gov) is the nation's leading funder of research on the brain and nervous system. The NINDS mission is to reduce the burden of neurological disease – a burden borne by every age group, by every segment of society, by people all over the world.
About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.
NINDS press team | EurekAlert!
Further reports about: > DNA > DNA samples > Gates Foundation > Massachusetts > Medical Wellness > NIH > NINDS > Nature Immunology > Neurological Disorder > PFN1 > familial ALS > gene mutation > health services > lateral sclerosis > medical research > motor neuron disease > nerve cell > neurological disease
New photocatalyst speeds up the conversion of carbon dioxide into chemical resources
29.05.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)
Copper hydroxide nanoparticles provide protection against toxic oxygen radicals in cigarette smoke
29.05.2017 | Johannes Gutenberg-Universität Mainz
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
29.05.2017 | Earth Sciences
29.05.2017 | Life Sciences
29.05.2017 | Physics and Astronomy