Rescue of a deficiency in ATP synthesis by transfer of MTATP6, a mitochondrial DNA-encoded gene, to the nucleus.
A T-->G transversion at nt 8993 in mitochondrial DNA of MTATP6 (encoding ATPase 6 of complex V of the respiratory chain) causes impaired mitochondrial ATP synthesis in two related mitochondrial disorders: neuropathy, ataxia and retinitis pigmentosa and maternally inherited Leigh syndrome. To overcome the biochemical defect, we expressed wildtype ATPase 6 protein allotopically from nucleus-transfected constructs encoding an amino-terminal mitochondrial targeting signal appended to a recoded ATPase 6 gene (made compatible with the universal genetic code) that also contained a carboxy-terminal FLAG epitope tag. After transfection of human cells, the precursor polypeptide was expressed, imported into and processed within mitochondria, and incorporated into complex V. Allotopic expression of stably transfected constructs in cytoplasmic hybrids (cybrids) homoplasmic with respect to the 8993T-->G mutation showed a significantly improved recovery after growth in selective medium as well as a significant increase in ATP synthesis. This is the first successful demonstration of allotopic expression of an mtDNA-encoded polypeptide in mammalian cells and could form the basis of a genetic approach to treat a number of human mitochondrial disorders.
Manfredi
Giovanni
G
Department of Neurology and Neuroscience, Cornell University, New York, New York, USA.
Fu
Jin
J
Ojaimi
Joseline
J
Sadlock
James E
JE
Kwong
Jennifer Q
JQ
Guy
John
J
Schon
Eric A
EA
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000096:biosynthesis* / Q000378:metabolism; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002874:Chromosome Mapping; D003062:Codon; D003600:Cytosol / Q000201:enzymology; D004272:DNA, Mitochondrial / Q000235:genetics* / Q000378:metabolism; D000939:Epitopes; D006801:Humans; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism; D025261:Mitochondrial Proton-Translocating ATPases; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D012150:Polymorphism, Restriction Fragment Length; D014176:Protein Biosynthesis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection
D003062:Codon; D004272:DNA, Mitochondrial; D000939:Epitopes; C501005:MT-ATP6 protein, human; D010455:Peptides; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D025261:Mitochondrial Proton-Translocating ATPases