Creation and characterization of mitochondrial DNA-depleted cell lines with "neuronal-like" properties

Mitochondrial dysfunction and attendant bioenergetic defects are increasingly recognized as playing an important role in neurodegenerative disorders. The increased attention on mitochondrial involvement points to the need for developing cell lines that have neuron-like characteristics for the genetic analysis and modeling of these diseases. We describe the creation of respiratory-deficient SH-SY5Y neuroblastoma cell lines (rho zero 64/5) by selectively depleting mitochondrial DNA through prolonged exposure to ethidium bromide. Oxygen consumption in these cells and activities of the electron transport chain enzyme complexes I and IV that contain subunits encoded by the mitochondrial genome are eliminated. In contrast, the function of complex II, a nuclear-encoded electron transport chain component, is largely intact in these cells. The rho zero 64/5 cells retain the ability to differentiate into cells with neuron-like phenotypes following treatment with phorbol ester or retinoic acid. Normal respiratory function is recovered by repopulation of rho zero 64/5 cells with exogenous human platelet mitochondria. The rho zero 64/5 cell line serves as a valuable model for the study of neurologic diseases suspected of involving mitochondrial dysfunction.