Posts tagged protein

ScienceDaily (July 23, 2012) — A team of University of Alberta researchers has identified a new class of compounds that inhibit the spread of prions, misfolded proteins in the brain that trigger lethal neurodegenerative diseases in humans and animals.

U of A chemistry researcher Frederick West and his team have developed compounds that clear prions from infected cells derived from the brain.

"When these designer molecules were put into infected cells in our lab experiments, the numbers of misfolded proteins diminished — and in some cases we couldn’t detect any remaining misfolded prions," said West.

West and his collaborators at the U of A’s Centre for Prions and Protein Folding Diseases say this research is not yet a cure, but does open a doorway for developing treatments.

"We’re not ready to inject these compounds in prion-infected cattle," said David Westaway, director of the prion centre. "These initial compounds weren’t created for that end-run scenario but they have passed initial tests in a most promising manner."

West notes that the most promising experimental compounds at this stage are simply too big to be used therapeutically in humans or animals.

Human exposure to prion-triggered brain disorder is limited to rare cases of Creutzfeldt-Jakob or mad cow disease. The researchers say the human form of mad cow disease shows up in one in a million people in industrialized nations, but investigating the disease is nonetheless well worth the time and expense.

"There is a strong likelihood that prion diseases operate in a similar way to neurodegenerative diseases such as Alzheimer’s, which are distressingly common around the world," said West.

Source: Science Daily

ScienceDaily (July 20, 2012) — Conditions such as Parkinson’s disease are a result of pathogenic changes to proteins. In the neurodegenerative condition of Parkinson’s disease, which is currently incurable, the alpha-synuclein protein changes and becomes pathological. Until now, there have not been any antibodies that could help to demonstrate the change in alpha-synuclein associated with the disease. An international team of experts led by Gabor G. Kovacs from the Clinical Institute of Neurology at the MedUni Vienna has now discovered a new antibody that actually possesses this ability.

"It opens up new possibilities for the development of a diagnostic test for Parkinsonism," says Kovacs, highlighting the importance of this discovery. "This new antibody will enable us to find the pathological conformation in bodily fluids such as blood or CSF." A clinical study involving around 200 patients is already underway, and the first definitive results are expected at the end of 2012. The tests being carried out in collaboration with the University Department of Neurology, led by Walter Pirker, are designed to determine the extent to which the new antibody can be used as an early diagnostic tool in order to understand the condition better and be able to treat it more effectively.

A step towards a blood test for Parkinson’s With Parkinsonism, the diseased form of alpha-synuclein, which has the same primary structure as the healthy form, undergoes an “abnormal fold.” Says Kovacs: “Until now, however, it was not possible to distinguish between the two.” The previous immunodiagnostic techniques only allowed the general presence of alpha-synuclein to be confirmed. The new, monoclonal antibody, however, which the researchers at the MedUni Vienna have developed in collaboration with the German biotech firm Roboscreen, is now able to detect a strategic part of the protein responsible for the structural changes. The results of the study have now been published in the journal Acta Neuropathologica.

Says Kovacs: “It is still not possible to say whether or not we will be able to diagnose Parkinson’s from a blood test, but this discovery certainly represents a major step in that direction.” Theoretically, it should be possible to diagnose Parkinson’s disease five to eight years before it develops.

In Austria, there are between 15,000 and 16,000 people living with Parkinson’s syndrome. Its frequency increases with age. As society becomes older, Parkinson’s disease, a degenerative condition of the brain, will become an increasingly widespread problem.

Source: Science Daily

ScienceDaily (July 20, 2012) — Scientists at the University of Manchester have uncovered how the internal mechanisms in nerve cells wire the brain. The findings open up new avenues in the investigation of neurodegenerative diseases by analysing the cellular processes underlying these conditions.

Illustration of spectraplakins in axonal growth organising microtubules. (Credit: Image courtesy of University of Manchester)

Dr Andreas Prokop and his team at the Faculty of Life Sciences have been studying the growth of axons, the thin cable-like extensions of nerve cells that wire the brain. If axons don’t develop properly this can lead to birth disorders, mental and physical impairments and the gradual decay of brain capacity during aging.

Axon growth is directed by the hand shaped growth cone which sits in the tip of the axon. It is well documented how growth cones perceive signals from the outside to follow pathways to specific targets, but very little is known about the internal machinery that dictates their behaviour.

Dr Prokop has been studying the key driver of growth cone movements, the cytoskeleton. The cytoskeleton helps to maintain a cell’s shape and is made up of the protein filaments, actin and microtubules. Microtubules are the key driving force of axon growth whilst actin helps to regulate the direction the axon grows.

Dr Prokop and his team used fruit flies to analyse how actin and microtubule proteins combine in the cytoskeleton to coordinate axon growth. They focussed on the multifunctional proteins called spectraplakins which are essential for axonal growth and have known roles in neurodegeneration and wound healing of the skin.

What the team demonstrate in this recent paper is that spectraplakins link microtubules to actin to help them extend in the direction the axon is growing. If this link is missing then microtubule networks show disorganised criss-crossed arrangements instead of parallel bundles and axon growth is hampered.

By understanding the molecular detail of these interactions the team made a second important finding. Spectraplakins collect not only at the tip of microtubules but also along the shaft, which helps to stabilise them and ensure they act as a stable structure within the axon.

This additional function of spectraplakins relates them to a class of microtubule-binding proteins including Tau. Tau is an important player in neurodegenerative diseases, such as Alzheimer’s, which is still little understood. In support of the author’s findings, another publication has just shown that the human spectraplakin, Dystonin, causes neurodegeneration when affected in its linkage to microtubules.

Talking about his research Dr Prokop said: “Understanding cytoskeletal machinery at the cell level is a holy grail of current cell research that will have powerful clinical applications. Thus, cytoskeleton is crucially involved in virtually all aspects of a cell’s life, including cell shape changes, cell division, cell movement, contacts and signalling between cells, and dynamic transport events within cells. Accordingly, the cytoskeleton lies at the root of many brain disorders. Therefore, deciphering the principles of cytoskeletal machinery during the fundamental process of axon growth will essentially help research into the causes of a broad spectrum of diseases. Spectraplakins like at the heart of this machinery and our research opens up new avenues for its investigation”

What Dr Prokop’s paper in the Journal of Neuroscience also demonstrates is the successful research technique using the fruit fly Drosophila. The team was able to replicate its findings regarding axon growth in mice which in turn means the findings can be translated to humans.

Dr Prokop points out fruit flies provide ideal means to make sense of these findings and essentially help to unravel the many mysteries of neurodegeneration.

Dr Prokop continues: “Understanding how spectraplakins perform their cellular functions has important implications for basic as well as biomedical research. Thus, besides their roles during axon growth, spectraplakins of mice and humans are clinically important for a number of conditions and processes including skin blistering, neuro-degeneration, wound healing, synapse formation and neuron migration during brain development. Understanding spectraplakins in one biological process will instruct research on the other clinically relevant roles of these proteins.”

Source: Science Daily

July 18, 2012

(Phys.org) — New research at the Hebrew University of Jerusalem sheds light on pluripotency—the ability of embryonic stem cells to renew themselves indefinitely and to differentiate into all types of mature cells. Solving this problem, which is a major challenge in modern biology, could expedite the use of embryonic stem cells in cell therapy and regenerative medicine. If scientists can replicate the mechanisms that make pluripotency possible, they could create cells in the laboratory which could be implanted in humans to cure diseases characterized by cell death, such as Alzheimer’s, Parkinson’s, diabetes and other degenerative diseases.

To shed light on these processes, researchers in the lab of Dr. Eran Meshorer, in the Department of Genetics at the Hebrew University’s Alexander Silberman Institute of Life Sciences, are combining molecular, microscopic and genomic approaches. Meshorer’s team is focusing on epigenetic pathways—which cause biological changes without a corresponding change in the DNA sequence—that are specific to embryonic stem cells.

The molecular basis for epigenetic mechanisms is chromatin, which is comprised of a cell’s DNA and structural and regulatory proteins. In groundbreaking research performed by Shai Melcer, a PhD student in the Meshorer lab, the mechanisms which support an “open” chromatin conformation in embryonic stem cells were examined. The researchers found that chromatin is less condensed in embryonic stem cells, allowing them the flexibility or “functional plasticity” to turn into any kind of cell.

A distinct pattern of chemical modifications of chromatin structural proteins (referred to as the acetylation and methylation of histones) enables a looser chromatin configuration in embryonic stem cells. During the early stages of differentiation, this pattern changes to facilitate chromatin compaction.

But even more interestingly, the authors found that a nuclear lamina protein, lamin A, is also a part of the secret. In all differentiated cell types, lamin A binds compacted domains of chromatin and anchors them to the cell’s nuclear envelope. Lamin A is absent from embryonic stem cells and this may enable the freer, more dynamic chromatin state in the cell nucleus. The authors believe that chromatin plasticity is tantamount to functional plasticity since chromatin is made up of DNA that includes all genes and codes for all proteins in any living cell. Understanding the mechanisms that regulate chromatin function will enable intelligent manipulations of embryonic stem cells in the future.

"If we can apply this new understanding about the mechanisms that give embryonic stem cells their plasticity, then we can increase or decrease the dynamics of the proteins that bind DNA and thereby increase or decrease the cells’ differentiation potential," concludes Dr. Meshorer. “This could expedite the use of embryonic stem cells in cell therapy and regenerative medicine, by enabling the creation of cells in the laboratory which could be implanted in humans to cure diseases characterized by cell death, such as Alzheimer’s, Parkinson’s, diabetes and other degenerative diseases.”

Source: PHYS.ORG

ScienceDaily (July 16, 2012) — While Spider-Man is capturing the imagination of theatergoers, real-life spider men in Upstate New York are working intently to save a young boy’s life.

UB researchers are developing a treatment for muscular dystrophy using a peptide found in the venom of a Chilean rose tarantula. (Credit: Image courtesy of University at Buffalo)

It all began in 2009, when Jeff Harvey, a stockbroker from the Buffalo suburbs, discovered that his grandson, JB, had Duchenne muscular dystrophy. The disease is fatal. It strikes only boys, causing their muscles to waste away.

Hoping to help his grandson, Harvey searched Google for promising muscular dystrophy treatments and, in a moment of serendipity, stumbled upon University at Buffalo scientist Frederick Sachs, PhD.

Sachs was a professor of physiology and biophysics who had been studying the medical benefits of venom. In the venom of the Chilean rose tarantula, he and his colleagues discovered a protein that held promise for keeping muscular dystrophy at bay. Specifically, the protein helped stop muscle cells from deteriorating.

Within months of getting in touch, Harvey and Sachs co-founded Tonus Therapeutics, a pharmaceutical company devoted to developing the protein as a drug. Though the treatment has yet to be tested in humans, it has helped dystrophic mice gain strength in preliminary experiments.

The therapy is not a cure. But if it works in humans, it could extend the lives of children like JB for years — maybe even decades.

Success can’t come quickly enough.

JB, now four, can’t walk down the stairs alone. When he runs, he waddles. He receives physical therapy and takes steroids as a treatment. While playing tee ball one recent day, he confided to his grandfather, “When I grow up, I want to be a baseball player.” It was a heartbreaking moment.

"Oh, I would be thrilled if you could be a baseball player," Harvey remembers replying. He’s doing everything he can to make sure that JB — and other boys like him — can live out their dreams.

Source: Science Daily

July 11, 2012

Communication between the brain and muscle must be strong for us to eat, breathe or walk. Now scientists have found that a protein known to be on the surface of muscle cells must be present in both tissues to ensure the conversation is robust.

Communication between the brain and muscle must be strong for us to eat, breathe or walk. Now scientists have found that a protein known to be on the surface of muscle cells must be present in both tissues to ensure the conversation is robust. Credit: Phil Jones

Scientists at the Medical College of Georgia at Georgia Health Sciences University have shown that without LRP4 in muscle cells and neurons, communication between the two cells types is inefficient and short-lived.

Problems with the protein appear to contribute to disabling disorders such as myasthenia gravis and other forms of muscular dystrophy. The MCG scientists reported finding antibodies to LRP4 in the blood of about 2 percent of patients with muscle-degenerating myasthenia gravis in Archives of Neurology earlier this year.

Scientists know that LRP4 plays an important role in the muscle cell, where it receives cues from the brain cell that it’s time to form the receptors that will be enable ongoing communication between the two, said Dr. Lin Mei, Director of the GHSU Institute of Molecular Medicine and Genetics and corresponding author of the study in the journal Neuron.

However when Dr. Haitao Wu deleted LRP4 just from muscle cells, a connection – albeit a weak one – still formed between muscle and brain cells. The mice survived several days during which they experienced some of the same muscle weakness as patients with myasthenia gravis. “That’s against the dogma,” Mei said. “If LRP4 is essential only in the muscle cells, how could the mice survive?” When they totally eliminated LRP4, neuromuscular junctions never formed and the mice didn’t survive.

Additional evidence suggests that LRP4 in the neurons is vital, said Wu, postdoctoral fellow and the study’s first author. “When we knocked out the LRP4 gene in the muscles, there was some redundant function coming from the motor neuron, like a rescue attempt,” he said. They documented the neuron reaching out to share LRP4 with the muscle cell. Unfortunately, the gesture was not sufficient.

"The nerve does not get the stop signal," Mei said, referencing images of too-long neurons that never got the message from the muscle that they have gone far enough. When they cut the elongated nerves, they found they didn’t contain enough vesicles, little packages of chemical messengers that are the hallmark of brain cell communication. On the receiving end, muscle cells developed receptors that were too small and too few – hence, the tenuous communication network. "When LRP4 in the muscle is taken out, not surprisingly, the muscle has some kind of a problem," Mei said. "What was very surprising was that the motor neurons also have problems.”

"The talk between motor neurons and muscle cells is very critical to the synapse formation and the very precise action between the two," Wu said. Mei’s lab earlier established that the conversation goes both ways.

The scientists believe about 60 percent of the LRP4 comes from muscle cells, about 20 percent from brain cells – which helps explain why the brain’s effort to share is insufficient – and the remainder from cells in spaces between the two. In addition to better explaining nerve-muscle communication, the scientists hope their findings will eventually enable gene therapy that delivers LRP4 to bolster insufficient levels in patients.

Other early and key players in establishing nerve-muscle conversation include agrin, a protein that motor neurons release to direct construction of the synapse, a sort of telephone line between the nerve and muscle. MuSK on the muscle cell surface initiates critical internal cell talk so synapses can form and receptors that enable specific commands will cluster at just the right spot.

Mei’s lab reported in Neuron in 2008 that agrin starts talking with LRP4 on the muscle cell surface, then recruits the enzyme MuSK to join the conversation. LRP4 and MuSK become major components of the receptor needed for the muscle cell to receive the message agrin is sending.

The agrin-MuSK signaling pathway has been implicated in muscular dystrophy, a group of genetic diseases that lead to loss of muscle control because of problems with neurons, muscle cells and/or their communication. Some reports have implicated a mutant MuSK as a cause of muscular dystrophy and autoantibodies (antibodies the body makes against itself) to MuSK have been found in the blood of some patients.

Provided by Georgia Health Sciences University

Source: medicalxpress.com

July 11, 2012

In a paper published in the July 11 online issue of Science Translational Medicine, researchers at the University of California, San Diego School of Medicine have identified two key regulatory proteins critical to clearing away misfolded proteins that accumulate and cause the progressive, deadly neurodegeneration of Huntington’s disease (HD).

This is a human neuron. UC San Diego scientists have identified a pair of proteins that help clear away other misfolded proteins responsible for the progressive degeneration of brain cells in Huntington’s disease. Credit: UC San Diego School of Medicine

The findings explain a fundamental aspect of how HD wreaks havoc within cells and provides “clear, therapeutic opportunities,” said principal investigator Albert R. La Spada, MD, PhD, professor of cellular and molecular medicine, chief of the Division of Genetics in the Department of Pediatrics and associate director of the Institute for Genomic Medicine at UC San Diego.

"We think the implications are significant," said La Spada. "It’s a lead we can vigorously pursue, not just for Huntington’s disease, but also for similar neurodegenerative conditions like Parkinson’s disease and maybe even Alzheimer’s disease.”

In HD, an inherited mutation in the huntingtin (htt) gene results in misfolded htt proteins accumulating in certain central nervous system cells, leading to progressive deterioration of involuntary movement control, cognitive decline and psychological problems. More than 30,000 Americans have HD. There are no effective treatments currently to either cure the disease or slow its progression.

La Spada and colleagues focused on a protein called PGC-1alpha, which helps regulate the creation and operation of mitochondria, the tiny organelles that generate the fuel required for every cell to function.

"It’s all about energy," La Spada said. "Neurons have a constant, high demand for it. They’re always on the edge for maintaining adequate levels of energy production. PGC-1alpha regulates the function of transcription factors that promote the creation of mitochondria and allow them to run at full capacity.”

Previous studies by La Spada and others discovered that the mutant form of the htt gene interfered with normal levels and functioning of PGC-1alpha. “This study confirms that,” La Spada said. More surprising was the discovery that elevated levels of PGC-1alpha in a mouse model of HD virtually eliminated the problematic misfolded proteins.

Specifically, PGC-1alpha influenced expression of another protein vital to autophagy – the process in which healthy cells degrade and recycle old, unneeded or dangerous parts and products, including oxidative, damaging molecules generated by metabolism. For neurons, which must last a lifetime, the self-renewal is essential to survival.

"Mitochondria get beat up and need to be recycled," La Spada said. "PGC-1alpha drives this pathway through another protein called transcription factor EB or TFEB. We were unaware of this connection before, because TFEB is a relatively new player, though clearly emerging as a leading actor. We discovered that even without PGC-1alpha induction, TFEB can prevent htt aggregation and neurotoxicity."

In their experiments, HD mice crossbred with mice that produced greater levels of PGC-1alpha showed dramatic improvement. Production of misfolded proteins was essentially eliminated and the mice behaved normally. “Degeneration of brain cells is prevented. Neurons don’t die,” said La Spada.

PGC-1alpha and TFEB provide two new therapeutic targets for Huntington’s disease, according to La Spada. “If you can induce the bioenergetics and protein quality control pathways of nervous system cells to function properly, by activating the PGC-1alpha pathway and promoting greater TFEB function, you stand a good chance of maintaining neural function for an extended period of time. If we could achieve the level of increased function necessary to eliminate misfolded proteins, we might nip the disease process in the bud. That would go a long way toward treating this devastating condition.”

Provided by University of California - San Diego

Source: medicalxpress.com