Dyanna Melo

Supervisor: Toshifumi Yokota

Project: Developing treatments for Duchenne muscular Ddystrophy (DMD)

Degree program:

Medicine & Dentistry-Medical Genetics

Lay abstract:

Duchenne muscular dystrophy (DMD) is a lethal genetic disorder that affects approximately 1 in 3,800 live male births. DMD patients do not produce a dystrophin protein due to mutations in the dystrophin gene. However, protein function can be restored by using DNA-like molecules called antisense oligonucleotides (AOs) which work by promoting exon skipping. Exons are protein-coding sequences of DNA within a gene that fit together like puzzle pieces. If one piece is out of place the puzzle does not serve its function. However, we can use AOs to skip certain exons to create puzzle pieces which fit together to perform a function. The dystrophin gene is the largest gene in the human genome and consists of 79 exons. Currently, there is one FDA approved AO drug for DMD called eteplirsen (which skips exon 51), but it faces many challenges such as that the drug only benefits approximately 13% of DMD patients and restoration of protein function varies between patients. If exons 45-55 could be skipped this would be more beneficial to DMD patients because approximately 50% of patients have mutations within this region. The protein structure after this region is skipped is more stable than the resulting protein after treatment with eteplirsen and restored function would be more universal between patients. Naturally, patients with exons 45-55 deleted have remarkably mild symptoms, adding to one of the many reasons why this region should be targeted in therapy. It has been previously shown in Yokota's Lab that morpholinos, a type of AO, can be used to skip exons 45-55 in cell and animal models, but a large number of morpholinos were needed. This is not clinically relevant as some morpholinos may be redundant and the price for this therapy is extremely expensive. We aim to develop a minimized cocktail of morpholinos needed to skip exons 45-55 at the same or greater efficiency as the larger cocktail, which can be used to restore dystrophin protein production and ameliorate DMD symptoms. This research will be conducted in vitro using a variety of patient muscle cell lines as well as in vivo using a humanized mouse model carrying the human DMD gene sequence. The efficacy and toxicity of the treatment will be measured using Reverse Transcriptase Polymerase Chain Reaction (RT-PCR), immunocytochemistry, western blotting and blood tests. This research will help towards improving the treatment options available for DMD patients as well as it will create headway in the field of exon-skipping to fuel research for other genetic disorders.

What motivated you to participate in this research?

Research has always been a great interest of mine as it has provided with me the opportunity to apply my knowledge that I’ve obtained throughout my degree and further explore new concepts. I’ve always been extremely passionate about the genetic link to human diseases and gene therapy. Being a part of the Yokota lab has given me the chance to explore my interests in the field of genetics and gene therapy.

What are your career aspirations?

I’ve always aspired to be a physician. As a physician, I could combine my passions of research, genetics, gene therapy and helping others.

How has this studentship helped you toward those aspirations?

As a physician, I believe it is extremely important to understand genetics and the basis of drug development. This studentship has allowed me to have a hands-on experience in the field of therapeutic research. This is will help me a better physician in the future as I will have a better understanding of scientific research and drug discovery that drives physicians and healthcare.