Mitochondria maintain their own genome (mtDNA), which is present in hundreds of copies per cell. Although depletion of mtDNA abundance leads to disease, including mtDNA depletion syndromes, we still do not fully understand the processes that determine mtDNA copy number. MtDNA depletion syndromes can be the result of mutations in machinery required to replicate the mtDNA, enzymes required for dNTP synthesis, or proteins that mediate mitochondrial morphology.
While the link between mtDNA copy number and the mtDNA replication machinery or dNTP pools is clear, it is less obvious how mitochondrial morphology impacts the mitochondrial genome. In the regard, the mtDNA genome is packaged into nucleoid structures that are typically evenly distributed throughout the mitochondrial network. Impairment to either mitochondrial fission or fusion processes, which determine the morphology of the mitochondrial network, can alter both the distribution and abundance of mtDNA. For example, pathogenic mutations in the core mitochondrial fusion (MFN2 and OPA1) and fission (DNM1L) proteins can cause mtDNA depletion. However, alterations to mtDNA as a result of impairment in other proteins regulating mitochondrial fusion and fission have not been well-described.
This seminar will discuss how studying mitochondrial disease genes can provide mechanistic insight into how mtDNA is regulated, with a focus on other proteins that regulate mitochondrial morphology.