Mitochondrial DNA affects tau phosphorylation in aging and Alzheimer's disease.

INTRODUCTION: Impaired mitochondrial function is seen in Alzheimer's disease (AD), but its role is unclear. Mitochondrial DNA (mtDNA) supports bioenergetic metabolism, but it is uncertain how it might influence AD neuropathology. METHODS: We used cytoplasmic hybrid (cybrid) cell lines made from SH-SY5Y cells expressing mtDNA from cognitively healthy (CH), mild cognitive impairment (MCI), or AD individuals to investigate the impact of mtDNA-determined mitochondrial function on amyloid, tau, and neurodegeneration (ATN) markers. Cybrid measurements were correlated with cognition and brain morphometry. RESULTS: Relative to cybrids expressing mtDNA from CH individuals, MCI and AD cybrids contained more phosphorylated tau-217 (p-tau217), p-tau181, and total tau. Cybrid p-tau217 correlated with plasma p-tau217 from the mtDNA donor (β = 0.605, p < 0.001). We observed negative relationships between cybrid p-tau217 and cognition and brain morphometry. MCI and AD cybrid proteomes showed mitochondrial dysfunction. DISCUSSION: mtDNA-determined mitochondrial function affects cell physiology in AD-relevant ways. Our study suggests that mtDNA affects ATN status and clinical state. HIGHLIGHTS: Mitochondrial DNA (mtDNA)-determined mitochondrial function drives Alzheimer's disease (AD) hallmarks. Cytoplasmic hybrid outcomes associate with mtDNA-donor clinical measures. Proteomic analyses indicate mitochondrial dysfunction in AD.