Defining the Molecular Composition of the Interspecies Barrier for Mitochondrial DNA Replication
Abstract
FY20 PRMRP Topic Area Addressed by the Proposed Research Project: Mitochondrial disease. Area of Encouragement: “Development of improved tools and animal models to study primary mitochondrial diseases and evaluate therapeutics.” Rationale: Mutations in mitochondrial DNA (mtDNA) are a prevailing cause of mitochondrial diseases, which can be fatal and can affect anyone, including military personnel and their families. Currently, treatment options for mitochondrial diseases are limited to symptom control and palliative care. Animal models of human disease are instrumental in developing and testing new drugs. Still, unfortunately, no faithful mouse models are broadly available to facilitate research or drug development for mitochondrial disease. Present-day methods for generating mouse models of mitochondrial disease caused by mtDNA mutations depend on the availability of mouse cells that carry mtDNA mutations equivalent to those found in human disease. However, such mutations are not only difficult but often impossible to induce. Over the past 30 years, humanized mice, generated by the reconstitution of human hematopoietic cells in immunodeficient mice, have revolutionized the study of human hematology and immunology, and have allowed us to recapitulate human cell-mediated immune diseases in vivo, proving superior in some respects even to nonhuman primate models. However, “humanization” in these models remains confined to the immune system. The long-term goal of this application is to humanize mice by reconstituting the human mitochondrial respiratory system in these animals. This would not only radically alter our approach to modeling mitochondrial disease by allowing the use of patient mtDNA from peripheral blood as starting material (and thus providing “personalized” mouse models), but also would enable the creation of faithful models of those mitochondrial diseases, which are impossible to model using the contemporary approach. The first stumbling block on this road is the inability of murine cells to stably maintain human mtDNA. Our overall hypothesis, therefore, is that mitochondrial RNA polymerase, PolRmt, is the key determinant of the interspecies barrier to mtDNA replication (IBMDR). Thus, expression of the proper hPolRmt isoform in murine cells would overcome the IBMDR and enable the eventual generation of “humanized” mice in which mitochondrial function is supported by human mtDNA. It is important to note here that the latest findings in the field of mtDNA research support the feasibility of our approach. The ultimate outcome of the proposed line of research is a “humanized” murine platform for personalized modeling mitochondrial disease using patient mtDNA. This platform will trivialize the existing crippling bottleneck in technology, which has thus far prevented the routine generation of accurate mouse models of mitochondrial disease caused by mtDNA mutations. It will do so by eliminating the requirement for mouse mtDNA carrying mutations equivalent to those found in human disease, since human mtDNA, which is abundant in the peripheral blood of patients, will be used instead. In the short term, the proposed studies will improve our understanding of mtDNA replication. They will also stimulate research into the poorly understood mechanisms of interaction and coordination between nuclear and mitochondrial genomes by providing a novel platform and tools for these studies. If successful, the proposed studies will lay the foundation for projects aimed at the optimization of transcription, translation, and/or respiratory chain function (as necessary) in humanized mouse cells. In the long term, these studies will lead to an emergence of a conceptually new approach to modeling mitochondrial disease in mice by supplying chimeric “humanized” mice. These mice, in which normal mitochondrial function will be supported by a human, rather than murine, mtDNA, will serve as a novel platform for the generation
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 05, 2021
- Source ID
- W81XWH2110161
Entities
People
- Mikhail F Alexeyev
Organizations
- United States Army
- University of South Alabama