Limitations of Allotopic Expression of Mitochondrial Genes in Mammalian Cells

Jose Oca-Cossio, Lesley Kenyon, Huiling Hao, Carlos T Moraes

Research output: Contribution to journalArticle

72 Citations (Scopus)

Abstract

The possibility of expressing mitochondrial DNA-coded genes in the nuclear-cytoplasmic compartment provides an attractive system for genetic treatment of mitochondrial disorders associated with mitochondrial DNA mutations. In theory, by recoding mitochondrial genes to adapt them to the universal genetic code and by adding a DNA sequence coding for a mitochondrial-targeting sequence, one could achieve correct localization of the gene product. Such transfer has occurred in nature, and certain species of algae and plants express a number of polypeptides that are commonly coded by mtDNA in the nuclear-cytoplasmic compartment. In the present study, allotopic expression of three different mtDNA-coded polypeptides (ATPase8, apocytochrome b, and ND4) into COS-7 and HeLa cells was analyzed. Among these, only ATPase8 was correctly expressed and localized to mitochondria. The full-length, as well as truncated forms of apocytochrome b and ND4 decorated the periphery of mitochondria, but also aggregated in fiber-like structures containing tubulin and in some cases also vimentin. The addition of a hydrophilic tail (EGFP) to the C terminus of these polypeptides did not change their localization. Overexpression of molecular chaperones also did not have a significant effect in preventing aggregations. Allotopic expression of apocytochrome b and ND4 induced a loss of mitochondrial membrane potential in transfected cells, which can lead to cell death. Our observations suggest that only a subset of mitochondrial genes can be replaced allotopically. Analyses of the hydrophobic patterns of different polypeptides suggest that hydrophobicity of the N-terminal segment is the main determinant for the importability of peptides into mammalian mitochondria.

Original languageEnglish
Pages (from-to)707-720
Number of pages14
JournalGenetics
Volume165
Issue number2
StatePublished - Oct 1 2003

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Mitochondrial Genes
Mitochondrial DNA
Cytochromes b
Mitochondria
Peptides
Genetic Code
Mitochondrial Diseases
Molecular Chaperones
Mitochondrial Membrane Potential
COS Cells
Vimentin
Tubulin
Hydrophobic and Hydrophilic Interactions
HeLa Cells
Genes
Cell Death
Mutation

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

Cite this

Limitations of Allotopic Expression of Mitochondrial Genes in Mammalian Cells. / Oca-Cossio, Jose; Kenyon, Lesley; Hao, Huiling; Moraes, Carlos T.

In: Genetics, Vol. 165, No. 2, 01.10.2003, p. 707-720.

Research output: Contribution to journalArticle

Oca-Cossio, J, Kenyon, L, Hao, H & Moraes, CT 2003, 'Limitations of Allotopic Expression of Mitochondrial Genes in Mammalian Cells', Genetics, vol. 165, no. 2, pp. 707-720.
Oca-Cossio, Jose ; Kenyon, Lesley ; Hao, Huiling ; Moraes, Carlos T. / Limitations of Allotopic Expression of Mitochondrial Genes in Mammalian Cells. In: Genetics. 2003 ; Vol. 165, No. 2. pp. 707-720.
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