“I think the myotonic dystrophy field has made great gains in understanding the mechanisms of this disease, and there a number of exciting therapeutic strategies underway,” Andrew Berglund says. “This includes clinical trials with antisense oligonucleotides that target the toxic RNA as well as other strategies that target other aspects of the disease.” 

Andrew Berglund, professor of biochemistry and molecular biology at the University of Florida in Gainesville, received an MDA research grant totaling $300,000 over three years to develop a therapeutic strategy for both types 1 and 2 myotonic dystrophy (DM1, DM2).

It is thought that the genetic defect underlying DM causes a toxic RNA, which accumulates in the nucleus of the cell and causes protein dysfunction by trapping proteins important for normal cell function. (RNA is the chemical step between DNA and protein manufacturing.) Some therapeutic approaches aim at degrading these toxic RNAs, or prevent them from trapping important cellular proteins. Berglund’s approach is to prevent the toxic RNA from even being produced in the first place.   

With colleagues, Berglund recently published proof-of-principle data supporting the approach they’ve developed, called IMPEDE (inhibition of microsatellite promoted expression of deleterious expansions), which showed that treatment with an FDA-approved drug called actinomycin D reduced toxic RNA production in DM1 cell and mouse models.

Now Berglund’s team is working to further develop this small-molecule approach. Small molecules have some advantages over other types of treatments — such as the ability to be given systemically and to get across the blood-brain-barrier.

If successful, this approach potentially could be used alone or in combination with other therapeutic strategies to treat myotonic dystrophy.

“My focus is to better understand the role that Cullin-3-related protein degradation may play in the pathological mechanism leading to the development of nemaline myopathy,” Jordan Blondelle says. “It’s important because the underlying mechanisms of this life-threatening disease currently are poorly understood.”

Jordan Blondelle, postdoctoral researcher at the University of California San Diego in La Jolla, was awarded an MDA development grant totaling $180,000 over three years to increase understanding of the underlying mechanisms in nemaline myopathy.

Muscle mass maintenance is tightly regulated by a balance between muscle growth and atrophy, reflecting the balance between protein synthesis and degradation at the cellular level. Accumulation of misfolded proteins or premature degradation of proteins is often associated with diseases such as skeletal muscle myopathies.

The degradation of muscle proteins is accomplished mainly through a cellular “clean-up and disposal system” called the ubiquitin-proteasome system, or UPS. The Cullin family of proteins, a key component of the UPS system, incorporate into complexes after which they are able to bind and mark unwanted proteins for degradation. Recently, mutations in several binding partners of Cullin-3, a Cullin protein family member, were found in people with severe forms of nemaline myopathy. These findings suggest a specific and important function for Cullin-3 targeted protein degradation during muscle development and maintenance.  

Using mutant mice in which Cullin-3 is depleted in muscles, Blondelle and colleagues determined that the protein is necessary for survival, and will now look at how the loss of Cullin-3 affects muscle development, structure and function.

The team expects to find new target proteins of the Cullin-3 complex that would be misregulated in the absence of Cullin-3 and responsible for the myopathy observed in mice. In addition, the team intends to decipher, for the first time, how protein degradation mediated by Cullin-3 is relevant for muscle physiology, and to provide insight into the pathological mechanisms leading to nemaline myopathy in people.

If successful, Blondelle’s work could inform the development of therapies for nemaline myopathy.  

“I have received other MDA grants which have been critical to these studies,” Dean Burkin says. “This new grant will allow us to move an exciting new integrin-targeting small molecule closer to clinical trials for Duchenne muscular dystrophy patients.”

Dean Burkin, professor of pharmacology and directory of cellular and molecular pharmacology and physiology graduate program at the University of Nevada School of Medicine in Reno, was awarded an MDA research grant totaling $300,000 over three years to test the effects of an existing FDA-approved drug on the function of heart and skeletal muscle in a mouse model of Duchenne muscular dystrophy (DMD).

DMD is caused by mutations in the DMD gene, which encodes the dystrophin protein. Dystrophin forms a molecular “glue” that binds muscle cells together and provides structural integrity, and its loss or deficiency in DMD causes progressive muscle weakness and results in premature death.

A second molecular glue, a protein called alpha7beta1 integrin, is also present in muscle, and studies in transgenic mouse models have shown that increased levels of alpha7beta1 can act as a surrogate for the absence of dystrophin and prevent disease progression.  

In collaboration with the National Center for Advancing Translational Sciences (NCATS) at the National Institutes of Health (NIH), Burkin and colleagues conducted a muscle cell-based test and screened more than 400,000 compounds to identify drugs that could enhance the activity of alpha7beta1. They identified a novel compound called SU9516 that increases levels of alpha7beta1 integrin protein and prevents muscle disease in the mdx mouse model of DMD.

SU9516 has an FDA-approved analog called sunitinib, and Burkin’s team will now test the effectiveness of this drug in mouse models of DMD. Since sunitinib already is FDA-approved (to treat some forms of cancer), successful outcomes of this study could lead to future clinical trials and rapid translation into a novel class of integrin-based therapeutics for DMD. 

“We believe that this drug, already approved for use in humans, will cure mitochondrial disease in animals,” Gino Cortopassi says. “If it does, we would take the data directly to the FDA to support a clinical trial in patients with mitochondrial myopathy.”

Gino Cortopassi, professor of molecular biosciences at the University of California, Davis, was awarded an MDA research grant totaling $300,000 over three years to optimize dosing in an FDA-approved drug called dimethyl fumarate, or DMF, in animal models of mitochondrial myopathy and Duchenne muscular dystrophy (DMD).

Mitochondria are small organelles found in cells. They are considered the “powerhouse” of the cell and are necessary to sustain life and support growth. When mitochondrial function is disrupted, high energy-demanding tissues such as brain and muscles are severely affected.

With a grant from MDA in 2009, Cortopassi and colleagues determined that the drug DMF could improve mitochondrial function. Only recently, however, have they come to understand that DMF works by increasing the number and activity of mitochondria in muscle. Since DMF has been used safely in hundreds of thousands of individuals with multiple sclerosis and psoriasis, its path to approval in other diseases could be quick. But in order for the FDA to approve clinical trials in humans that could assess whether the drug is effective in mitochondrial myopathy or DMD, positive results in validated animal models of these diseases are necessary.

Now, Cortopassi and his team will work to optimize dosing and timing for maximum drug benefit, test the mechanism of the drug, and determine the functional muscle benefit in mitochondrial myopathy and DMD mouse models. The group intends to identify the maximum effective dose of DMF and determine whether it can improve function in the mice.

If successful, Cortopassi’s work could provide data to support an investigational new drug (IND) application to the FDA for a new therapy for mitochondrial myopathy and/or DMD.

https://doi.org/10.55762/pc.gr.76838

"I feel that the DM field is making impressive strides in deciphering the exact pathogenic mechanisms unleashed by the trinucleotide repeat expansion,” Auinash Kalsotra says. “This knowledge will undoubtedly lead to the development of new treatment modalities for this debilitating disease."

Auinash Kalsotra, assistant professor and Beckman Fellow at the University of Illinois in Urbana, was awarded an MDA research grant totaling $300,000 over three years to shed light on how defects develop in the heart in type 1 myotonic dystrophy (DM1).

While the mutation that underlies DM1 affects multiple tissues, cardiac defects are the second leading cause of death in individuals with DM1. However, the molecular mechanism(s) responsible for the cardiac pathogenesis remain poorly understood.

Kalsotra and colleagues have discovered that in DM1-diseased heart, the fetal non-muscle isoform of an RNA binding protein called RBFOX2 is significantly upregulated. By forcing the expression of the non-muscle isoform of RBFOX2 in adult mouse hearts, they have reproduced many of the cardiac dysfunctions observed in DM1, including arrhythmias and cardiac conduction defects.

Now, the team will determine how the balance between muscle and non-muscle isoforms for RBFOX2 is achieved during normal heart development. In addition, they will investigate how this regulation is disrupted in DM1 and why the selective expression of non-muscle RBFOX2 isoform triggers a cardiac disease phenotype.

These finding will offer important insight into how cardiac abnormalities develop in DM1, and may inform new approaches for cardiac care in individuals with DM1.  

“Without the support of MDA, young scientists like myself will not have the means to focus and shine a spotlight on rare diseases such as FSHD and other muscular dystrophies,” Angela Lek says.

Angela Lek, a postdoctoral research fellow at Boston Children’s Hospital in Massachusetts, was awarded an MDA development grant totaling $180,000 over three years to use cutting-edge techniques and a novel approach to search for drug targets in facioscapulohumeral muscular dystrophy (FSHD).

Disease severity among FSHD patients varies widely, and differences may be attributable to genetic modifiers (genes that minimize or exacerbate symptoms). Such modifiers also may explain why some relatives of people who have FSHD and who have the same permissive genetics are not affected.

With colleagues, Lek will work to identify genetic modifiers that appear to allow some individuals to appear “resistant” to FSHD.

Using the latest in genome-editing technology, the team will perform genetic modifications that result in systematically switching on every gene, one by one, across the entire human genome. They hypothesize that one or more of these gene switches will result in reduction of FSHD-related cell toxicity, making it a modifier gene in FSHD that can potentially be used to ameliorate disease symptoms in patients.

Candidate modifier genes will be cross-referenced to genomic sequencing data derived from people with FSHD and their asymptomatic carrier relatives, as a possible explanation for their clinical variance. The team will then further validate these genes with functional rescue experiments in a zebrafish model of FSHD, and also measure their ability to change the molecular disease signature of FSHD patient cells.

Once validated, these target genes could serve as concrete targets for therapy development.

“There are no available disease-modifying treatments for SBMA,” Andrew Lieberman says. “Grants from the MDA provide critical support for translational studies in this area of unmet clinical need.”

Gerald Abrams Collegiate Professor of Pathology Andrew Lieberman, at University of Michigan Medical School in Ann Arbor, was awarded an MDA research grant totaling $300,000 over three years to test a modified antisense oligonucleotide (ASO) therapy to treat spinal-bulbar muscular atrophy (SBMA). 

Working with colleagues at Ionis Pharmaceuticals, Lieberman will complete preclinical studies in a mouse model to establish the safety and efficacy of a new type of therapy to silence expression (activity) of the gene that is mutated in SBMA. They plan to deliver the drug under the skin and target skeletal muscle — in fact, the new drug has been specifically designed for efficient uptake by muscle.

The team hypothesizes that the enhanced targeting of muscle by the new drug will enable robust gene silencing at lower doses, thereby limiting off-target toxicity while concurrently enhancing activity in a variety of disease-relevant muscles.

The group plans to establish the extent to which the modified drug triggers enhanced gene silencing and prevents disease onset in SBMA mice, and will determine effects of the drug in symptomatic SBMA mice. These studies are expected to provide essential efficacy data in a preclinical model.

The work is part of an academic-industry partnership between Ionis Pharmaceuticals and the Lieberman laboratory. If successful, the work could de-risk further investment by Ionis and shed light on whether a similar muscle-targeting strategy could work for other muscle diseases as well. 

“Obtaining a molecular diagnosis is extremely important for patients and families with NMDs,” James Lupski says, “as it provides recurrence risk information, relevant management of disease, can sometimes provide prognostic information, and can facilitate entry into disease-specific clinical trials.”

James Lupski, Cullen Professor of Molecular and Human Genetics and professor of pediatrics at Baylor College of Medicine in Houston, was awarded an MDA research grant totaling $300,000 over three years to facilitate new gene discovery and new biological insights into the pathobiology of a host of neuromuscular diseases (NMDs).

Determining genetic diagnoses in NMDs can be difficult due to the large number of disease-causing genes and significant heterogeneity, as well as overlap, in clinical symptoms between patients. With colleagues, Lupski aims to advance molecular diagnostics for NMD patients that remain undiagnosed after clinical diagnostic whole exome sequencing (WES), and enhance discovery of novel disease genes.

The team first will re-analyze clinical exome data in a research setting to confirm that the genetic cause, and thus a diagnosis, has not been missed. They will then perform exome sequencing for the patient’s parents and/or other family members in order to find spontaneous, or de novo, mutations and novel genes associated with NMDs. For cases that remain unsolved, they will then implement RNA sequencing from affected tissue, if available. The advantage of RNA sequencing from muscle tissue is that it can provide direct evidence of the functional impact of a mutation.

Lupski’s work will provide a direct benefit to individuals whose initial gene sequencing was not informative, by helping them obtain a molecular diagnosis. These results are important in informing disease management, prognosis and family planning decisions, and in helping determine eligibility for participation in disease-specific registries and clinical trials.

Hi work is also likely to lead to the discovery of new NMD-causing genes and improve our understanding of the mechanisms that can lead to disease in a wider array of individuals.  

“Numerous inherited and acquired cardiac diseases are directly linked to deficits in dystrophin protein, including, for example, DMD, in which there is the complete loss of the dystrophin protein, and by viral infection-induced cardiomyopathy, wherein intact dystrophin is cleaved into truncated fragments,” Joseph Metzger says. “A detailed understanding of the structure-function relationship of dystrophin fragments, truncations and isoforms is required for future long-term success of DMD therapies.” 

Joseph Metzger, professor and chair of the department of integrative biology and physiology at the University of Minnesota Medical School in Minneapolis, was awarded an MDA research grant totaling $300,000 over three years to assess different versions of shortened dystrophin protein and determine which is most stable and able to provide a functional benefit to the heart in Duchenne muscular dystrophy (DMD).

A number of therapies in development for DMD center on the introduction of a truncated (shortened) form of dystrophin protein. These therapies include exon skipping drugs, gene therapies, and CRISPR-based therapies.

However, different versions of the shortened protein have been found to vary in stability and function.

With the goal of determining which version of truncated dystrophin protein is best, Metzger and colleagues will examine the effects of truncation on the stability of dystrophin over time and on its ability to protect the mouse heart from damage, with future plans to extend the work to include skeletal muscle studies as well.

Critical new information will be obtained on the stability of truncated dystrophins essential for future success of dystrophin restitution in muscular dystrophy models. If successful, the detailed structure-function studies could have critical implications for the long-term success of current and proposed gene-based therapies for DMD.  

“For C9ORF72 ALS, dipeptide repeat protein (DPR) aggregation seems to be uncorrelated with degeneration in autopsy tissue,” Timothy Miller says. “Further, studies measuring levels of DPRs in various brain regions via immunoassay found few or no correlations between DPR concentration and clinical characteristics. Thus, while DPRs are an attractive target for therapeutics, there remains a missing link between promising cell/animal work and human disease.”

Timothy Miller, professor of neurology at Washington University in St. Louis, was awarded an MDA research grant totaling $282,417 over three years to shed light on ALS (amyotrophic lateral sclerosis) disease mechanisms.

The most common genetic cause of ALS is a hexanucleotide repeat expansion in the C9ORF72 gene, causing at least 30 percent of familial ALS and 5-10 percent of sporadic ALS cases. This repeat expansion causes the accumulation of abnormal dipeptide repeat proteins (DPRs), which aggregate in human tissues and have been found to be toxic in cellular and animal models. However, pathological characteristics of the DPRs do not seem to correlate with clinical characteristics or degenerative severity in patients, making it challenging to determine whether these DPRs directly contribute to degeneration in human ALS.

Using innovative methodologies, Miller and colleagues will investigate aspects of DPRs to determine their significance to human disease. The team will develop a novel way to understand DPR size in human tissues and cerebral spinal fluid (CSF), as well as a method to determine the turnover rate of DPRs in CSF of C9ORF72 expansion carriers. The turnover rate of DPRs may correlate with disease measures and could help define when and how to apply therapeutics.

The results from Miller’s work could have important implications in the understanding and treatment of C9ORF72 ALS. In addition, DPRs could serve as biomarkers that could directly inform the design of future clinical trials.  

“Overall,” says Philippe Moullier, “the results of this program will provide important preclinical proof-of-concept to support the future development of clinical trials for the treatment of the cardiomyopathy in DMD patients — a necessary evolution in a comprehensive translational strategy for DMD treatment.”

Philippe Moullier, head of the Gene Therapy Institute at the French National Institute of Health and Medical Research (INSERM), was awarded an MDA research grant totaling $300,000 over three years for preclinical work in the development of gene therapy for Duchenne muscular dystrophy (DMD).

With colleagues, Moullier will test two mini-dystrophin genes to determine which of the two best preserves the appropriate biochemical properties of full-length dystrophin protein and which has the most robust protective effect on the heart.

The better of the two candidates will then undergo further study to determine optimal dosing.

Moullier’s aim is to deliver preclinical data that will enable translation to gene therapy treatment for cardiac disease in DMD.  

"Udai Pandey says his team’s small molecule screening project could help identify drugs that might be useful for testing in vertebrate ALS models and, ultimately, in human clinical trials."

Udai Pandey, associate professor at the Children’s Hospital of Pittsburgh in Pennsylvania, was awarded an MDA research grant totaling $300,000 over three years to identify new drugs for ALS (amyotrophic lateral sclerosis) caused by a mutation in the FUS gene.

Pandey and colleagues are interested in understanding the basic mechanisms of FUS-mediated ALS and are working to identify drugs that can suppress mechanisms associated with the disease. 

The team recently performed a large drug screen, using a library of 400,000 drugs in a yeast model of FUS-mediated neurodegeneration, and identified about 80 drugs that strongly suppress toxicities associated with FUS. Now they are working to follow up on testing these drugs in a fly model of FUS, as well as in nerve cells created from ALS patient stem cells.

If successful, Pandey’s pre-clinical studies may help identify potential drugs for ALS caused by the FUS gene or related forms of ALS that could be tested in clinical trials. 

"Our study will first provide critical insights into the mechanistic basis by which direct inactivation of PTEN in muscle cells benefits the function of dystrophic muscle,” Feng Yue says. “More importantly, we aim to develop a potent pharmacological approach to target PTEN in dystrophic muscle, which could directly lead to the development of novel therapeutic applications for clinical treatment of DMD.”

Feng Yue, research associate scientist at Purdue University in West Lafayette, Ind., was awarded an MDA development grant totaling $175,409 over three years to evaluate the therapeutic potential of a protein called phosphatase and tensin homolog (PTEN) in Duchenne muscular dystrophy (DMD).

In DMD, muscles are more susceptible to injury but they cannot keep up with repair, which eventually leads to muscle loss and weakness.

With colleagues, Yue aims to develop potential therapies that promote regrowth of dystrophic muscle and, in turn, increase muscle strength. The team has developed a strategy that involves inhibiting the action of a natural protein that limits muscle cell growth, called PTEN.

In healthy muscle, the level of PTEN is very low, but it’s found in much higher levels in DMD-affected muscles.

Working with a preclinical mouse model of DMD, the team will first study whether inhibiting PTEN in muscle cells could boost muscle growth and increase muscle strength in DMD mice. The team will then work to develop a safe, high-efficiency pharmacological approach to specifically deliver a well-known PTEN inhibitor to the skeletal muscle of DMD mice, and examine its effect on muscle functional recovery.

If successful, Yue’s work could lead to the development of novel therapeutic strategies for clinical treatment of DMD.