Identificación de moléculas aprobadas por la FDA para tratar SCA6

Escrito por la Dra. Hannah Shorrock Editado por la Dra. Larissa Nitschke. Publicado inicialmente en el 7 de mayo de 2021. Traducción al español fueron hechas por FEDAES y Carlos Barba.

Pastor y sus colegas identifican pequeñas moléculas aprobadas por la FDA que reducen selectivamente la proteína tóxica expandida con poliglutamina en SCA6.

Apuntar selectivamente a los genes que causan enfermedades sin alterar las funciones celulares es esencial para el desarrollo exitoso de la terapia. En la ataxia espinocerebelosa tipo 6 (SCA6), lograr esta selectividad es particularmente complicado ya que el gen que causa la enfermedad produce dos proteínas que contienen un tracto de poliglutamina expandido. En este estudio, Pastor y sus colegas identificaron varias moléculas pequeñas aprobadas por la Administración de Alimentos y Medicamentos (FDA) que reducen selectivamente los niveles de una de estas proteínas que contienen poliglutamina sin afectar los niveles de la otra proteína, que es esencial para la función normal del cerebro. Mediante el uso de medicamentos ya aprobados por la Administración de Alimentos y Medicamentos de los Estados Unidos Para tratar otras enfermedades, conocidas como medicamentos aprobados por la FDA, el equipo espera reducir el período de tiempo para el desarrollo de la terapia preclínica.

SCA6 es una ataxia autosómica dominante que causa un deterioro progresivo del movimiento y la coordinación. Esto se debe a la disfunción y muerte de las células cerebrales, incluidas las neuronas de Purkinje en el cerebelo . SCA6 es causada por una expansión de repetición CAG en el gen CACNA1A. CACNA1A codifica dos proteínas: la subunidad a1A, la principal subunidad formadora de poros del canal de iones de calcio dependiente de voltaje de tipo P / Q , así como un factor de transcripción llamado a1ACT.

La subunidad a1A es esencial para la vida. Su función se ve menos afectada por la presencia del tracto de poliglutamina expandido que la de a1ACT. El factor de transcripción, a1ACT, controla la expresión de varios genes implicados en el desarrollo de las células de Purkinje. La expresión de la proteína a1ACT que contiene un tracto de poliglutamina expandido en ratones causa atrofia y ataxia cerebelosa. Si bien la reducción de los niveles de la subunidad a1A puede tener poco efecto sobre la enfermedad de SCA6 pero afectar la función normal de las células cerebrales, la reducción de los niveles de a1ACT puede mejorar la enfermedad en SCA6. Por lo tanto, Pastor y sus colegas decidieron probar la hipótesis de que la reducción selectiva de los niveles de la proteína a1ACT sin afectar los niveles de la proteína a1A puede ser un enfoque terapéutico viable para SCA6.

Colorful pile of medicines in blister packs which color are White, Yellow, Black and Pink pills.
Mediante el uso de medicamentos ya aprobados por la FDA, el equipo espera reducir el período de tiempo para el desarrollo de la terapia preclínica.  Foto utilizada bajo licencia por Wanchana Phuangwan / Shutterstock.com .
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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.

Spotlight: The CMRR Ataxia Imaging Team

Location: University of Minnesota, MN, USA

Year Research Group Founded:  2008

What models and techniques do you use?

A photo of the CMRR Ataxia Imaging Team
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
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?

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. 

Initiative for Columbia Ataxia and Tremor Logo. It is a circle containing a lion with its whiskers to look like a neuron

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

Identifying FDA-approved molecules to treat SCA6

Written by Dr Hannah Shorrock Edited by Dr. Larissa Nitschke

Pastor and colleagues identify FDA-approved small molecules that selectively reduce the toxic polyglutamine-expanded protein in SCA6.

Selectively targeting disease-causing genes without disrupting cellular functions is essential for successful therapy development. In spinocerebellar ataxia type 6 (SCA6), achieving this selectivity is particularly complicated as the disease-causing gene produces two proteins that contain an expanded polyglutamine tract. In this study, Pastor and colleagues identified several Food and Drug Administration (FDA) approved small molecules that selectively reduce the levels of one of these polyglutamine-containing proteins without affecting the levels of the other protein, which is essential for normal brain function. By using drugs already approved by the United States Food and Drug Administration to treat other diseases, referred to as FDA-approved drugs, the team hopes to reduce the time frame for pre-clinical therapy development.

SCA6 is an autosomal dominant ataxia that causes progressive impairment of movement and coordination. This is due to the dysfunction and death of brain cells, including Purkinje neurons in the cerebellum. SCA6 is caused by a CAG repeat expansion in the CACNA1A gene. CACNA1A encodes two proteins: the a1A subunit, the main pore-forming subunit of the P/Q type voltage-gated calcium ion channel, as well as a transcription factor named a1ACT.

The a1A subunit is essential for life. Its function is less affected by the presence of the expanded polyglutamine tract than that of a1ACT. The transcription factor, a1ACT, controls the expression of various genes involved in the development of Purkinje cells. Expressing a1ACT protein containing an expanded polyglutamine tract in mice causes cerebellar atrophy and ataxia. While reducing levels of the a1A subunit may have little effect on SCA6 disease but impact normal brain cell function, reducing levels of a1ACT may improve disease in SCA6. Therefore, Pastor and colleagues decided to test the hypothesis that selectively reducing levels of the a1ACT protein without affecting levels of the a1A protein may be a viable therapeutic approach for SCA6.

Colorful pile of medicines in blister packs which color are White, Yellow, Black and Pink pills.
By using drugs already approved by the FDA, the team hopes to reduce the time frame for pre-clinical therapy development. Photo used under license by Wanchana Phuangwan/Shutterstock.com.
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