SCA3 Archives -

Snapshot: What is Riluzole?

Riluzole, often sold under the trade name Rilutek, is a medication used for the treatment of amyotrophic lateral sclerosis (ALS). ALS is a fatal neurodegenerative disease that mainly affects neurons controlling muscle movements. The drug was approved by the FDA (1995), Health Canada (1997), and the European Commission (1996). It helps slow down disease progression and may extend patient survival. The medication is available in tablet and liquid form, generally well-tolerated. There are sometimes mild side effects, which may include loss of appetite, nausea, and abdominal pain.

Close up of a woman taking a pill with water — Riluzole has been used to treat ALS, and research has suggested it may also help with forms of ataxia. It is currently being tested in clinical trials. Photo used under license by fizkes/Shutterstock.com.

How does it work?

Exactly how Riluzole slows disease progression remains unknown. However, it is thought that its neuroprotective effects likely stem from reducing a phenomenon known as excitotoxicity.

Neurons communicate with each other through chemical messengers called neurotransmitters. The signalling of these messengers needs to be tightly controlled. Too little or too much signaling will disrupt normal functions of the brain and cause damage to cells. Excitotoxicity is the result of excessive signaling by glutamate, one of the most abundant neurotransmitters in the brain. Glutamate is also associated with many neurodegenerative diseases.

Riluzole prevents this excessive signaling through several mechanisms. It is hypothesized that the effectiveness of riluzole in ALS treatment is the result of this neuroprotective property.

Riluzole for Ataxia

The neuroprotective function of riluzole has been a point of interest for the treatment of other neurodegenerative diseases since its approval. Multiple clinical trials have been conducted for patients with neurodegenerative diseases including Parkinson’s disease, Huntington’s disease, multiple system atrophy, and ataxia.

In 2010, a pilot trial was conducted with 40 patients with cerebellar ataxia who showed a lower level of motor impairment, measured by the International Cooperative Ataxia Rating Scale. A follow-up trial was then performed in 2015 for 55 patients with spinocerebellar ataxia (SCA) or Friedreich’s ataxia. Similarly, patient impairment had improved by an alternative measurement using the Scale for the Assessment and Rating of Ataxia. These findings indicate the possibility of riluzole being an effective treatment for cerebellar ataxia. However, more long-term studies and ones that are specific to different types of SCA need to be conducted to confirm the results.

Riluzole in Development

Even though riluzole was discovered more than 25 years ago, variations of the drug are still under development. As ALS often affects a patient’s ability to swallow, a new formulation of riluzole that is absorbed by placing it under your tongue is being developed under the name Nurtec.

Another prodrug version of riluzole, named Troriluzole (BHV-4157), may be better absorbed by the body with fewer side effects. Troriluzole is currently in phase three clinical trial for patients with different types of SCA. The trial is expected to be complete by November 30, 2021, and will hopefully provide more insight into the effectiveness of Troriluzole in SCA patients.

If you would like to learn more about Riluzole, take a look at these resources by the ClinicalTrials.gov and the Mayo Clinic.

Snapshot written by Christina (Yi) Peng and edited by Terry Suk.

Evaluating the long-term safety of lentiviral gene therapy in SCA3 mice

Written by Dr. Ambika Tewari Edited by Dr. Hayley McLoughlin

Lentiviral expression of an shRNA against ataxin-3 was well-tolerated and produced no measurable adverse effects in wild-type mice.

Evaluating the safety profile is a necessary and crucial step in qualifying a therapy for use in patients. Gene therapy is an experimental technique that has demonstrated tremendous progress in the treatment or reversal of a disease, specifically monogenic disorders. Carefully investigating the safety and tolerance of gene therapy is important to gauge its suitability for clinical trials. Gene therapy tools can be used in different ways to achieve the same therapeutic effect: the faulty gene can be replaced with a healthy copy, the mutated gene can be repaired, or the mutant copy of the gene can be silenced. You can learn more about gene therapy in this pat SCAsource Snapshot.

Spinocerebellar ataxia type 3 (SCA3) or Machado-Joseph disease (MJD) causes progressive loss of neurons in the spinal cord, and several regions of the brain. This includes the cerebellum, brainstem, striatum and substantia nigra. These neurons have crucial functions. Without these neurons, patients experience motor incoordination, loss of balance, and in severe cases, premature death. While great progress continues to be made in understanding how a mutation in a single gene, Ataxin-3, causes the symptoms of SCA3, there is still no treatment to stop the disease progression. As a monogenic disorder, SCA3, like other Spinocerebellar ataxias (SCA), is a promising candidate for gene therapy. While there are no approved gene therapies for SCA yet, there any several research labs and companies working towards achieving this goal.

An artist's drawing of scientists standing infront of a giant piece of DNA and drugs — This is truly an exciting time for gene therapy, but it is also important to keep the safety of patients a top priority. *Photo used under license by Visual Generation/*Shutterstock.com.

The researchers in this study have been working on gene therapy for SCA3 since 2008. They have researched how gene therapy could offer protection against further decline, in several cell and mouse models of SCA3. They used an approach where they decreased the levels of the mutant Ataxin-3 gene while leaving the normal Ataxin-3 gene intact. This is known as allele-specific targeting. They demonstrated that using this technique, they could significantly reduce the behavioral and neuropathological changes that occur in SCA3 mice. Mice treated with the gene therapy showed improvements in their balance and motor coordination.

Gene therapy in its most basic form involves two components, the gene that will replace or remove the diseased gene and a vector that will transport this new gene to its site of action. The most commonly used vectors today are adeno-associated virus (AAVs) followed by retrovirus. These viruses have been specifically engineered to deliver their passenger to the specified location. While both vectors have been through several years of preclinical and clinical testing for numerous gene therapy candidates, there are questions that remain regarding their safety. (1) Does the gene therapy product continue to be expressed in the targeted area long-term; (2) If there is long-term expression does it cause any adverse measurable effects to the targeted area; (3) Does the long-term expression affect the normal functioning of the targeted cells/organ.

Spotlight: The CMRR Ataxia Imaging Team

Location: University of Minnesota, MN, USA

Year Research Group Founded: 2008

What disease areas do you research?

What models and techniques do you use?

Mouse models
Human Participants
Magnetic Resonance Imaging and Spectroscopy
Brain Connectivity Mapping
Computational & biophysical models of diffusion

A photo of the CMRR Ataxia Imaging Team in 2019. Front row, left to right – Diane Hutter, Christophe Lenglet (PI), Gulin Oz (PI), Katie Gundry, Jayashree Chandrasekaran Back row, left to right: Brian Hanna, James Joers, Pramod Pisharady, Kathryn France, Pierre-Gilles Henry (PI), Dinesh Deelchand, Young Woo Park, Isaac Adanyeguh (insert)

Research Group Focus

What shared research questions is your group investigating?

We use high field, multi-nuclear magnetic resonance imaging (MRI) and spectroscopy (MRS) to explore how diseases impact the central nervous system. These changes can be structural, functional, biochemical and metabolic alterations. For example, we apply advanced MRI and MRS methods in neurodegenerative diseases and diabetes.

We also lead efforts in research taking place at multiple different cities across the United States and the world. As you can imagine, studies spread out across such a big area require a lot of coordination and standardization. We design robust MRI and MRS methods to be used in clinical settings like these.

Another important question for our team is how early microstructural, chemical and functional changes can be detected in the brain and spinal cord by these advanced MR methods. We are interested in looking at these changes across all stages of disease.

Why does your group do this research?

The methods we use (MRI and MRS) can provide very helpful information to be used in clinical trials. These biomarkers we look at can provide quantitative information about how a disease is progressing or changing.

There is good evidence that subtle changes in the brain can be detected by these advanced MR technologies even before patients start having symptoms. If we better understand the earliest changes that are happening in the brain, this can in turn enable interventions at a very early stage. For example, we could treat people even before brain degeneration starts to take place.

Why did you form a research group connecting multiple labs?

We came together to form the CMRR Ataxia Imaging Team to benefit from our shared and complementary expertise, experience, and personnel. We can do more together than we could apart.

Are you recruiting human participants for research?

Yes, we are! We are looking for participants for multiple different studies. You can learn more about the research we are recruiting for at the following links: READISCA, TRACK-FA, NAF Studies, and FARA Studies. More information is also available through the UMN Ataxia Center.

A photo of the CMRR Ataxia Imaging Team in 2016, in front of the historic 4T scanner where the first functional MR images were obtained, in CMRR courtyard. Left to right – Christophe Lenglet (PI), Sarah Larson, Gulin Oz (PI), Dinesh Deelchand, Pierre-Gilles Henry (PI), James Joers, Diane Hutter

What Labs Make Up the CMRR Ataxia Imaging Team?

The Oz Lab

Principal Investigator: Dr. Gulin Oz

Year Founded: 2006

Our focus is on MR spectroscopy, specifically neurochemistry and metabolism studies. We focus on spinocerebellar ataxias. Also, we have been leading MRS technology harmonization across different sites and vendors.

The Henry Lab

Principal Investigator: Dr. Pierre-Gilles Henry

Year Founded: 2006

We develop advanced methods for MR spectroscopy and motion correction. Then apply these new methods to the study of biochemistry and metabolism in the brain and spinal cord in various diseases. We have been working on ataxias since 2014.

Fun Fact about the Henry Lab: The French language can often be heard in discussions in our lab!

The Lenglet Lab

Principal Investigator: Dr. Christophe Lenglet

Year Founded: 2011

We develop mathematical and computational strategies for human brain and spinal cord connectivity mapping. We do this using high field MRI. Our research aims at better understanding the central nervous system anatomical and functional connectivity. We are especially interested in looking at this in the context of neurological and neurodegenerative diseases.

Fun Fact

Members of our team have their roots in 7 countries (US, Turkey, France, India, Mauritius, South Korea, Ghana) and 4 continents (North America, Europe, Asia, Africa)

For More Information, check out the Center for Magnetic Resonance Research (CMRR) Website!

Written by Dr. Gulin Oz, Dr. Pierre-Gilles Henry, and Dr. Christophe Lenglet, Edited by Celeste Suart

Spotlight: The Kuo Lab

Principal Investigator: Dr. Sheng-Han Kuo

Location: Columbia University, New York, NY, United States

Year Founded: 2012

What disease areas do you research?

What models and techniques do you use?

Mouse models
Post-mortem patient tissue
Optogenetics
Human physiology
EEG (electroencephalogram)
Neuromodulation

Kuo Lab group photo. — This is a group picture of the Kuo Lab. From the left to right: Nadia Amokrane, Chi-Ying (Roy) Lin, Sara Radmard, Sheng-Han Kuo (PI), Chih-Chun (Charles) Lin, Odane Liu, Chun-Lun Ni , Meng-Ling Chen, Natasha Desai, David Ruff.

Research Focus

What is your research about?

We study how mishaps and damage in the cerebellum lead to the symptoms experienced by ataxia and tremor patients. By looking at human brains, as well as brains from mouse models, we study how different changes in brain structure can lead to symptoms. This includes how well different parts of the brain can communicate with each other.

Why do you do this research?

When you ask patients about the challenges living with ataxia or tremor, they will talk to you about their symptoms. Symptoms can make different activities of daily living very challenging! By connecting specific brain changes to specific symptoms, we want to develop treatment options that target specific diseases. By doing this, we hope to improve patient’s quality of life.

The Kuo lab is part of the Initiative for Columbia Ataxia and Tremor. It’s a new Initiative at Columbia University to bring a group of physicians, scientists, surgeons, and engineers to advance the knowledge of the cerebellum and to develop effective therapies for ataxia and tremor.

Are you recruiting human participants for research?

Yes, we are! We are looking for participants for clinical research and trials. You can learn more about the studies we are currently recruiting for at this link.

Fun Fact

In the Kuo Lab, we call ourselves “the Protector of the Cerebellum in New York City”.

For More Information, check out the Kuo Lab Website!

We are looking for new graduate students and postdoctoral researchers to join our team. If you are interested in our work, please reach out to us

Written by Dr. Sheng-Han Kuo, Edited by Celeste Suart

Failure to repair DNA damage may be linked to SCA3

Written by Dr. Ambika Tewari Edited by Dr. Maria do Carmo Costa

Mutations in Ataxin-3 protein prevent the normal functioning of a DNA repair enzyme leading to an accumulation of errors

Cells are bombarded by thousands of DNA damaging events each day from internal and external sources. Internal sources include routine processes that occur within cells that generate reactive byproducts, while external sources include ultraviolet radiation. This DNA damage can be detrimental to cells. But the coordination of many DNA repair proteins helps to maintain the integrity of the genome. This prevent the accumulation of mutations that can lead to cancer.

DNA repair proteins play very important roles in the nervous system. During development, cells are actively growing and dividing and can incur many errors during these processes. Therefore, it is not surprising that numerous DNA repair proteins are expressed in the mammalian brain to prevent the accumulation of DNA damage. To much DNA damage can produce devastating consequences.

Damaged DNA molecule — Ataxin-3 plays a role in a DNA repair pathway which fixes double-strand DNA break. If these breaks are not fixed, there are devastating consequences. Photo used under license by Rost9/Shutterstock.com.

In fact, DNA repair deficiencies usually result in profound nervous system dysfunction in humans. Examples include neurodegeneration, microcephaly and brain tumors. Altered DNA repair signaling has been implicated in neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. This implicates DNA repair proteins in genome maintenance in the nervous system. There are many different types of DNA damage and DNA repair. Each repair process has its own proteins and sequence of events that lead to either repair or cell death.

Ataxin-3 is known for its role in Spinocerebellar ataxia type 3 (SCA3), an autosomal dominant disorder caused by a repeat expansion in the ATXN3 gene. Symptoms are progressive and include prominent ataxia, impaired balance, spasticity and eye abnormalities. These symptoms are primarily a result of cerebellum dysfunction, but brainstem and spinal cord regions also show abnormalities in SCA3 patients. Recent studies have shown that ataxin-3 is part of a complex of proteins that repair single-strand DNA breaks. A crucial member of this complex, polynucleotide kinase 3’-phosphatase (PNKP), is actively involved in not only repairing single-strand but also double-strand breaks. Since the activity of PNKP is dependent on ataxin-3, this group of researchers were eager to investigate whether ataxin-3 also functioned in the repair of double-strand DNA damage.