Sanfilippo disease is a rare disorder caused by the failure of enzymes to break down specific kinds of complex carbohydrates, resulting in their accumulation in cells and often severe physical and neurological problems – and sometimes early death.
In a paper published in the March 4 issue of the Journal of Biological Chemistry, researchers at the University of California, San Diego School of Medicine, led by Jeffrey D. Esko, PhD, professor in the Department of Cellular and Molecular Medicine, describe the build-up of a novel secondary metabolite in Sanfilippo disease, a discovery that could improve understanding of the disease's pathology and refine diagnostic techniques.
Sanfilippo is one of a group of genetically inherited metabolic disorders called mucopolysaccharidoses, all of which involve the inability of different lysosomal enzymes to catabolize or break down glycosaminoglycans – complex sugar carbohydrates that help cells build skin, bone, cartilage, tendons and connective tissues.
"It's a very ordered sequence of degradation," said Esko, co-director of the Glycobiology Research and Training Center at UC San Diego. "Interference with any of the steps in the enzymatic process results in an accumulation of metabolites, which causes lyosomal dysfunction. Cells become constipated, leading to internal changes and dysfunction."
For patients with severe mucopolysaccharidosis, the consequences can be catastrophic. As incompletely degraded glycosaminoglycans accumulate in cells and tissues, they cause permanent, progressive damage that affects appearance, physical abilities, organ function and, most profoundly, mental development. Children with the disease can experience severe neuropathology and significant early mortality. It's estimated that 1 in 25,000 children in the United States have one of several forms of the disease. Some mucopolysaccharidoses can be temporarily treated with enzyme replacement therapies, but the body's blood-brain barrier blocks neurological benefit. There is no current cure.
"The three approved drugs on the market mask the genetic defect by supplementing the missing enzymes," said Esko. "They can help resolve storage in many organs, but not the brain because the enzymes do not cross the barrier. And they are very, very expensive."
In the new research, Esko and colleague William C. Lamanna, PhD, studied enzymatic activity in Sanfilippo patient fibroblasts, a type of cell most commonly found in connective tissues. They noted that defective enzymatic activity resulted in the accumulation of not just a glycosaminoglycan called heparan sulfate, but also a secondary metabolite called dermatan sulfate. Sanfilippo cells had levels of dermatan sulfate two- to five-fold higher than normal.
The combined accumulation of heparan sulfate with dermatan sulfate, researchers said, may explain some of the distinct pathological features of Sanfilippo disease. The emergence of dermatan sulfate as an additional biomarker for Sanfilippo disease could be useful in detection and diagnosis, though Esko said studies using patient tissue biopsies or blood or urine samples remain to be conducted.
"Right now, this discovery probably won't change the current therapy for Sanfilippo" said Lamanna, "but it does improve what we know about how the disease works and how to diagnose it."
The work follows related research published in 2010 in Molecular Therapy by Esko, Yitzhak Tor, PhD, UCSD Department of Chemistry and Biochemistry and Moores Cancer Center and colleagues that described a new type of targeting process for delivering modified enzymes to cells.
Co-authors of the JBC paper are Roger Lawrence and Stephane Sarrazin, both from the UCSD Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center.
Scott LaFee | EurekAlert!
Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction