New Funding for SBMA Research

The MDA announced the funding of $9.9 million dollars in research grants. The grant below is for the study of Kennedy's Disease.

Carlo Rinaldi, Ph.D., associate professor and clinician scientist at the University of Oxford in England, was awarded an MDA Development Grant to study how variants in the gene of the androgen receptor (AR) protein cause spinal-bulbar muscular atrophy (SBMA) and investigate whether a novel antisense oligonucleotide therapy approach can target these toxic variants. The results of the study will provide a better understanding of SBMA disease mechanisms, as well as develop a new therapy potentially capable of treating the disease.

This work has potential implications for other diseases of the motor unit as well, including spinal muscular atrophy (SMA) and ALS. This grant is co-funded by the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM).

Additional information was provided on another page:

“Better understanding of the underlying disease mechanisms, coupled with improvement of gene vector design, therapeutic gene selection, and methods of delivery, have made gene therapy a realistic option for neuromuscular conditions — and neurological diseases in general — for which no treatment option was available until few years ago. Many challenges still lie ahead, but we have good reasons to be very optimistic for the future.”

Carlo Rinaldi, associate professor and clinician scientist at the University of Oxford in England, was awarded an MDA Development Grant totaling $120,000 over 3 years to study the role of androgen receptor isoforms in SBMA pathogenesis and the potential as therapeutic targets. This grant is co-funded by the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM).

Mutations in the gene encoding the androgen receptor (AR) protein cause spinal and bulbar muscular atrophy (SBMA). SBMA is an adult-onset neuromuscular condition affecting males with unmet clinical need. It is not undestood how mutations in AR lead to primary degeneration of motor neurons and muscle in patients. The activity of AR and other hormone receptors can be modulated in human cells by isoforms and/or splice variants, which may block or enhance their functions.

Dr. Rinaldi and colleagues plan to investigate the role of AR alternative isoforms in mediating SBMA toxicity. By revealing how these isoforms regulate AR activity in health and disease, researchers expect to better understand the mechanisms of disease in SBMA and provide a novel rational therapeutic target. If successful, the work could pinpoint tissue-specific targets for therapy development, with implications not only for SBMA but for other diseases of the motor unit as well, including spinal muscular atrophy and amyotrophoic lateral sclerosis.

Is ASO a potential treatment for Kennedy’s Disease?

This is a follow up to my November 15, 2017, article, “MDAAnnounces SBMA Research Grant.” The research paper was a little over my head (nothing new for me), so I asked the KDA’s resident biology professor, Ed Meyertholen, to explain what Dr. Lieberman’s research was about. Below is Ed’s summary of the grant. For a short primer, I have included the link to a video on DNA-RNA.

"The grant the Andy Lieberman received was to continue the research on the use of Anti-Sense Oligonucleotides (ASO) as a treatment for Kennedy’s Disease (KD). To best understand how it works, it is important to remember the following:

1. KD is believed to be the result of a misfolded protein, specifically, the protein known as the Androgen Receptor (AR).

2. Proteins are built of specific sequences of amino acids, thus to make a protein, one must have amino acids and the sequence of the amino acids of the protein of interest.

3. The sequence of amino acids for any protein are hard coded into our genes - our DNA.  Thus to make a particular protein, the cell must find the gene that codes for the sequence for that protein and read the code to get the sequence.  The structure of the cell that makes the protein is the ribosome.

4. In KD, the misfolded protein is known as the Androgen Receptor (AR) and it misfolds because our DNA has an error in the sequence.  So, when our cells want to synthesize the AR, our instructions are faulty and when we make the resulting protein, it somehow causes cells to die albeit, slowly.

5. Protein synthesis requires two major steps, the first is the synthesis of an RNA copy (RNA is like DNA) of the gene (DNA) which codes for the protein of interest (this occurs in the nucleus).  The RNA synthesis is known as transcription.

6. The RNA copy (which contains the code for the protein) leaves the nucleus and goes to the ribosome.  Here the code is read and the protein is synthesized.  This actual making of the protein is known as translation.

7.  An ASO is a specially designed fragment of RNA that binds only to a specific RNA.  An ASO can be designed to bind specifically to any given RNA.  In this case, the ASO binds only to the RNA that is used to make the AR.  When the ASO binds to the RNA, the cell responds by destroying the RNA (that is what it does) - thus the RNA to make the AR is destroyed before the protein is made and thus no AR is synthesized and thus, it is hoped, no KD.

8.  Andy's grant is, as I understand it, will try to test this procedure on mice models of KD and involve investigating the best ways to deliver the ASO.  Let me also add, there have been several published studies that have shown that ASO's are effective in preventing KD in mice.  Other ASO's have been developed to treat other diseases and just recently, one was approved for use in a disease called Spinal Muscular Atrophy (this is not KD)."  

SBMA Study published regarding the AR113Q Muscle

This research paper was published a month ago.

Rescue of metabolic alterations in AR113Q skeletal muscle by peripheral androgen receptor gene silencing

Elisa Giorgetti, Zhigang Yu, Jason P. Chua, Ryosuke Shimamura, Lili Zhao, Fan Zhu, Sriram Venneti, Maria Pennuto, Yuanfang Guan, Gene Hung, and Andrew P. Lieberman1,

Highlights

•Decreased expression of carbohydrate metabolic genes characterizes AR113Q muscle
•AR113Q skeletal muscle shows decreased glycolysis and altered mitochondria
•Peripheral gene silencing by ASO rescues expression of muscle energy metabolism genes
•Altered muscle energy utilization contributes to non-neuronal disease manifestations

Summary

Spinal and bulbar muscular atrophy (SBMA), a progressive degenerative disorder, is caused by a CAG/glutamine expansion in the androgen receptor (polyQ AR). Recent studies demonstrate that skeletal muscle is an important site of toxicity that contributes to the SBMA phenotype. Here, we sought to identify critical pathways altered in muscle that underlie disease manifestations in AR113Q mice. This led to the unanticipated identification of gene expression changes affecting regulators of carbohydrate metabolism, similar to those triggered by denervation. AR113Q muscle exhibits diminished glycolysis, altered mitochondria, and an impaired response to exercise. Strikingly, the expression of genes regulating muscle energy metabolism is rescued following peripheral polyQ AR gene silencing by antisense oligonucleotides (ASO), a therapeutic strategy that alleviates disease. Our data establish the occurrence of a metabolic imbalance in SBMA muscle triggered by peripheral expression of the polyQ AR and indicate that alterations in energy utilization contribute to non-neuronal disease manifestations.