Saturday, September 30, 2023
9/30/2023
PROJECT SUMMARY/ABSTRACT Significant advances in gene discovery in the field of hearing and deafness have raised a great interest in developing new therapeutic approaches for genetic deafness. Hearing loss (HL), is the most common sensory deficit worldwide, affecting the quality of life of people of all ages. Despite the progress in the understanding of genetic etiologies and the molecular mechanisms involved in deafness, no effective therapies in restoring the natural hearing are as yet available. Given the massive burden posed by hearing problems and the emerging landscape of gene editing technology, it is now essential to address the unmet medical need and to pursue new strategies for treatment of inherited hearing loss. Recent reports of preclinical studies for developing targeted therapeutic approaches for inherited deafness have opened promising avenues for precision medicine in hearing loss. Recent reports have yielded encouraging results in preclinical trials of virally mediated gene therapy for inherited deafness. One disorder of interest is DFNA9, an autosomal dominant nonsyndromic late-onset HL with variable vestibular dysfunction, caused by mutations in COCH, encoding cochlin, the most abundantly detected protein in the inner ear. This disease model is similar to and representative of the majority of the genetic HL disorders with a dominant mode of inheritance with an underlying deleterious gain-of-function/dominant-negative mechanism of the mutant protein. The goal of this project is to develop a gene therapy strategy to treat hearing loss associated with DFNA9, along with training of a research fellow in the fields of human genetics of deafness. To achieve these goals, we plan to utilize state-of-the-art CRISPR-Cas9 gene editing technology to develop an allele-specific targeting approach, and to test its efficacy in halting or mitigating the development or progression of hearing loss in a knock-in (KI) mouse model of DFNA9 associated with the dominant COCH p.A449T mutation. Preliminary in vitro studies support the specificity of the developed CRISPR-Cas9 reagents and strategies. Furthermore, additional very recent phenotypic characterization of our novel Coch A449T KI mouse model at eight to nine months is consistent with late-onset hearing loss. We plan to perform more in-depth phenotyping of the Coch A449T KI mouse model, and to explore the mechanism of pathogenicity. We further plan to evaluate the efficiency and specificity of in vivo CRISPR-Cas9 target gene disruption in prevention or mitigation of progressive hearing loss. Carrying out the project aims will provide substantial progress in development of the essential steps required for translation of gene therapy into clinical application. This project will establish a knowledgeable research fellow in the field of hereditary deafness and gene therapy, who plans to lead research in precision medicine for hearing loss.
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