Visualizing Mitochondrial Ribosomal RNA and Mitochondrial Protein Synthesis in Human Cell Lines

Author(s):  
Matthew Zorkau ◽  
Yasmin Proctor-Kent ◽  
Rolando Berlinguer-Palmini ◽  
Andrew Hamilton ◽  
Zofia M. Chrzanowska-Lightowlers ◽  
...  
1991 ◽  
Vol 11 (4) ◽  
pp. 2236-2244 ◽  
Author(s):  
A Chomyn ◽  
G Meola ◽  
N Bresolin ◽  
S T Lai ◽  
G Scarlato ◽  
...  

A severe mitochondrial protein synthesis defect in myoblasts from a patient with mitochondrial myopathy was transferred with myoblast mitochondria into two genetically unrelated mitochondrial DNA (mtDNA)-less human cell lines, pointing to an mtDNA alteration as being responsible and sufficient for causing the disease. The transfer of the defect correlated with marked deficiencies in respiration and cytochrome c oxidase activity of the transformants and the presence in their mitochondria of mtDNA carrying a tRNA(Lys) mutation. Furthermore, apparently complete segregation of the defective genotype and phenotype was observed in the transformants derived from the heterogeneous proband myoblast population, suggesting that the mtDNA heteroplasmy in this population was to a large extent intercellular. The present work thus establishes a direct link between mtDNA alteration and a biochemical defect.


1991 ◽  
Vol 11 (4) ◽  
pp. 2236-2244
Author(s):  
A Chomyn ◽  
G Meola ◽  
N Bresolin ◽  
S T Lai ◽  
G Scarlato ◽  
...  

A severe mitochondrial protein synthesis defect in myoblasts from a patient with mitochondrial myopathy was transferred with myoblast mitochondria into two genetically unrelated mitochondrial DNA (mtDNA)-less human cell lines, pointing to an mtDNA alteration as being responsible and sufficient for causing the disease. The transfer of the defect correlated with marked deficiencies in respiration and cytochrome c oxidase activity of the transformants and the presence in their mitochondria of mtDNA carrying a tRNA(Lys) mutation. Furthermore, apparently complete segregation of the defective genotype and phenotype was observed in the transformants derived from the heterogeneous proband myoblast population, suggesting that the mtDNA heteroplasmy in this population was to a large extent intercellular. The present work thus establishes a direct link between mtDNA alteration and a biochemical defect.


A genetic analysis of the resistance phenotype of a recently described chloramphenicol-resistant variant derived from the human cell line, HeLa (MC63), has been undertaken. Whole cells or enucleated fragments, produced by treatment with cytochalasin B, were fused with chloram­phenicol-sensitive mouse, or human cells. Enucleated cells (cytoplasts) act as very efficient donors of the resistance phenotype in fusions with other human cell lines derived from HeLa. We conclude that chloram­phenicol resistance is determined cytoplasmically. Transfer of resistance to unrelated human cell lines occurred at much lower frequency and we were unable to demonstrate transfer to mouse cells. An examination of mitochondrial protein synthesis in the fusion products of cytoplasts and whole cells suggested that mixed populations of mitochondria from both parental cells were maintained under the conditions of selection.


2008 ◽  
Vol 181 (7) ◽  
pp. 1117-1128 ◽  
Author(s):  
Robert W. Gilkerson ◽  
Eric A. Schon ◽  
Evelyn Hernandez ◽  
Mercy M. Davidson

Mitochondrial DNA (mtDNA) is packaged into DNA-protein assemblies called nucleoids, but the mode of mtDNA propagation via the nucleoid remains controversial. Two mechanisms have been proposed: nucleoids may consistently maintain their mtDNA content faithfully, or nucleoids may exchange mtDNAs dynamically. To test these models directly, two cell lines were fused, each homoplasmic for a partially deleted mtDNA in which the deletions were nonoverlapping and each deficient in mitochondrial protein synthesis, thus allowing the first unequivocal visualization of two mtDNAs at the nucleoid level. The two mtDNAs transcomplemented to restore mitochondrial protein synthesis but were consistently maintained in discrete nucleoids that did not intermix stably. These results indicate that mitochondrial nucleoids tightly regulate their genetic content rather than freely exchanging mtDNAs. This genetic autonomy provides a molecular mechanism to explain patterns of mitochondrial genetic inheritance, in addition to facilitating therapeutic methods to eliminate deleterious mtDNA mutations.


1981 ◽  
Vol 1 (4) ◽  
pp. 321-329
Author(s):  
C J Doersen ◽  
E J Stanbridge

HeLa cells sensitive to the mitochondrial protein synthesis inhibitors erythromycin (ERY) and chloramphenicol (CAP) and HeLa variants resistant to the effects of these drugs were purposefully infected with drug-sensitive and -resistant mycoplasma strains. Mycoplasma hyorhinis and the ERY-resistant strain of Mycoplasma orale, MO-ERYr, did not influence the growth of HeLa and ERY-resistant ERY2301 cells in the presence or absence of ERY. M. hyorhinis also did not affect the growth of HeLa and CAP-resistant Cap-2 cells in the presence or absence of CAP. However, both HeLa and Cap-2 cells infected with the CAP-resistant strain of M. hyorhinis, MH-CAPr, were more sensitive to the cytotoxic effect of CAP. This may be due to the glucose dependence of the cells, which was compromised by the increased utilization of glucose by MH-CAPr in these infected cell cultures. In vitro protein synthesis by isolated mitochondria was significantly altered by mycoplasma infection of the various cell lines. A substantial number of mycoplasmas copurified with the mitochondria, resulting in up to a sevenfold increase in the incorporation of [3H]leucine into the trichloroacetic acid-insoluble material. More importantly, the apparent drug sensitivity or resistance of mitochondrial preparations from mycoplasma-infected cells reflected the drug sensitivity or resistance of the contaminating mycoplasmas. These results illustrate the hazards in interpreting mitochondrial protein synthesis data derived from mycoplasma-infected cell lines, particularly putative mitochondrially encoded mutants resistant to inhibitors of mitochondrial protein synthesis.


1967 ◽  
Vol 46 (3) ◽  
pp. 599-603 ◽  
Author(s):  
S. Bose ◽  
B.P. Gothoskar ◽  
W.G. Coutinho ◽  
K.J. Ranadive

1993 ◽  
Vol 21 (6) ◽  
pp. 1449-1455 ◽  
Author(s):  
Henrik Leffers ◽  
Annette H. Andersen

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