Rhabdomyosarcoma rho(0) cells: isolation and characterization of a mitochondrial DNA depleted cell line with 'muscle-like' properties

Mutations of mitochondrial DNA are a significant cause of neuromuscular dis ease. Pathological mutant mitochondrial DNA has been studied in control nuc lear backgrounds. These experiments entailed transfer of patient-derived mi tochondria to rho(0) cells that lack mtDNA. A limitation of these studies h as been the fact that the control nuclear backgrounds were unrelated to the affected tissues of patients. Therefore a rhabdomyosarcoma cell line that has 'muscle-like' properties was tested to determine whether it could be de pleted of mtDNA. A human rhabdomyosarcoma cell line was treated with the DN A intercalating dye ethidium bromide (3,8-diamino-5-ethyl-6-phenylphenanthr idinium bromide) for 45 days. The treatment induced complete and permanent loss of mitochondrial DNA (rho(0)) in the rhabdomyosarcoma cells, as mtDNA remained undetectable after 8 months of growth in medium without drug. Cruc ially, the rhabdomyosarcoma rho(0) cells retained the ability to differenti ate into myotubes with expression of muscle specific isoenzymes. The rhabdo myosarcoma rho(0) cell line provides a model system for studying pathologic al mutant mtDNA in cells that more closely resemble human muscle than the h itherto available human rho(0) cell lines. (C) 2000 Elsevier Science B.V. A ll rights reserved.