Systematic Pipeline for ADAR-Mediated Transcript Therapeutics in Rett Syndrome
Abstract
The studies proposed in this application were developed in response to the Fiscal Year 2022 Peer Reviewed Medical Research Program Funding Opportunity for the Topic Area Rett syndrome and the strategic goals to develop and validate a novel and innovative therapeutic intervention for the treatment of this severe disorder that places a heavy emotional and financial burden on parents and caretakers. Rett syndrome (RTT) is an early-onset neurodevelopmental disorder that affects approximately 1 in 10,000 girls. This disorder is characterized by normal development but is then interrupted by the loss of previously acquired social and motor skills (such as speaking and walking) that begins at 6-30 months of age. Additionally, respiratory and gastrointestinal problems, seizures, anxiety, and repetitive behaviors may subsequently emerge that persist throughout adulthood. Advances in molecular genetics have identified mutations in several genes associated with this syndrome, although 90%-95% of patients diagnosed with classic Rett syndrome have been shown to carry spontaneous mutations in the MECP2 gene. The MECP2 gene encodes a protein that is expressed throughout the body, yet it is most highly expressed in neurons and is essential for nervous system function. While several therapeutic strategies for Rett syndrome are being pursued, currently there are no effective treatments for this disorder and no approaches to repair the underlying mutations in the MECP2 gene. Recent advances in CRISPR-mediated gene targeting technologies have provided an opportunity for to correct genetic mutations identified in the DNA of patients diagnosed with numerous genetic disorders, including Rett syndrome. Despite the promise of such approaches however, CRISPR-mediated gene editing has several limitations that include the potential to make changes at inappropriate places in the genome, the potential for immune responses to large bacterial proteins that are used for this approach, the requirement for cellular delivery of multiple therapeutic components, the potential imprecision of this approach even when the modification occurs in the correct region of the DNA, and inefficient DNA modification in several cell types including, most notably, neurons in the brain. In recent years, the use or targeting of RNA molecules, rather than DNA, has become a promising strategy for therapeutic intervention and many RNA-based therapeutics have been approved for indications as diverse as spinal muscular atrophy, the reduction of LDL-cholesterol, and immunization against SARS-CoV-2, the virus responsible for COVID-19. As an alternative approach to CRISPR-mediated engineering of genetic mutations, several lines of investigation have focused upon the repair of mutant RNA transcripts by taking advantage of a normal cellular process in which specific adenosines are converted to inosine residues in RNA to increase the diversity of encoded protein expression and function. Being able to selectively modify an adenosine of one’s choice in MECP2 RNA, and convert it to inosine, provides a powerful therapeutic approach by which to correct a subset of MECP2 mutations for Rett syndrome patients. Advantages to targeted RNA editing include the fact that RNA modifications are transient, eliminating concerns associated with permanent DNA alterations, that it can be directed by the delivery of a single, small therapeutic RNA, and that it takes advantage of normal cellular enzymes to efficiently modify MECP2 transcripts in neurons. We have developed a strategy to select short, engineered RNAs that will promote the efficient repair of specific adenosine residues in MECP2 transcripts, thereby eliminating the mutations in the encoded protein products. For these studies, we have chosen to focus upon the repair of two distinct MECP2 mutations using a test tube-based system with MECP2 transcripts, the enzymes that catalyze the conversion of adenosine to inosine, and a large populat
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2024
- Source ID
- HT94252310111
Entities
People
- Ronald Emeson
Organizations
- United States Army
- Vanderbilt University