scholarly journals Mitochondrial nucleoids maintain genetic autonomy but allow for functional complementation

2008 ◽  
Vol 181 (7) ◽  
pp. 1117-1128 ◽  
Author(s):  
Robert W. Gilkerson ◽  
Eric A. Schon ◽  
Evelyn Hernandez ◽  
Mercy M. Davidson
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Molecular Mechanism ◽  
Cell Lines ◽  
Mitochondrial Protein ◽  
Functional Complementation ◽  
Mitochondrial Protein Synthesis ◽  
Protein Assemblies ◽  
Mtdna Mutations ◽  
Mitochondrial Nucleoids

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.

scholarly journals In vitro genetic transfer of protein synthesis and respiration defects to mitochondrial DNA-less cells with myopathy-patient mitochondria.

1991 ◽  
Vol 11 (4) ◽  
pp. 2236-2244 ◽  
Author(s):  
A Chomyn ◽  
G Meola ◽  
N Bresolin ◽  
S T Lai ◽  
G Scarlato ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Human Cell ◽  
Mitochondrial Myopathy ◽  
Mitochondrial Protein ◽  
Human Cell Lines ◽  
Mitochondrial Protein Synthesis ◽  
Direct Link ◽  
Genetic Transfer

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.

Mitochondrial DNA Medicine

2007 ◽  
Vol 27 (1-3) ◽  
pp. 5-9 ◽  
Author(s):  
Salvatore DiMauro
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Mitochondrial Protein ◽  
Point Mutations ◽  
Specific Protein ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Genetics ◽  
Protein Coding ◽  
Protein Coding Genes ◽  
Mitochondrial Medicine

The small, maternally inherited mitochondrial DNA (mtDNA) has turned out to be a hotbed of pathogenic mutations: 15 years into the era of ‘mitochondrial medicine’, over 150 pathogenic point mutations and countless rearrangements have been associated with a variety of multisystemic or tissue-specific human diseases. MtDNA-related disorders can be divided into two major groups: those due to mutations in genes affecting mitochondrial protein synthesis in toto and those due to mutations in specific protein-coding genes. Here we review the mitochondrial genetics and the clinical features of the mtDNA-related diseases.

scholarly journals The Deafness-Associated Mitochondrial DNA Mutation at Position 7445, Which Affects tRNASer(UCN) Precursor Processing, Has Long-Range Effects on NADH Dehydrogenase Subunit ND6 Gene Expression

1998 ◽  
Vol 18 (10) ◽  
pp. 5868-5879 ◽  
Author(s):  
Min-Xin Guan ◽  
José Antonio Enriquez ◽  
Nathan Fischel-Ghodsian ◽  
Ram S. Puranam ◽  
Catherine P. Lin ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Cell Lines ◽  
Nadh Dehydrogenase ◽  
Control Level ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Precursor Processing ◽  
Mtdna Mutations ◽  
Trna Precursor

ABSTRACT The pathogenetic mechanism of the deafness-associated mitochondrial DNA (mtDNA) T7445C mutation has been investigated in several lymphoblastoid cell lines from members of a New Zealand pedigree exhibiting the mutation in homoplasmic form and from control individuals. We show here that the mutation flanks the 3′ end of the tRNASer(UCN) gene sequence and affects the rate but not the sites of processing of the tRNA precursor. This causes an average reduction of ∼70% in the tRNASer(UCN) level and a decrease of ∼45% in protein synthesis rate in the cell lines analyzed. The data show a sharp threshold in the capacity of tRNASer(UCN) to support the wild-type protein synthesis rate, which corresponds to ∼40% of the control level of this tRNA. Strikingly, a 7445 mutation-associated marked reduction has been observed in the level of the mRNA for the NADH dehydrogenase (complex I) ND6 subunit gene, which is located ∼7 kbp upstream and is cotranscribed with the tRNASer(UCN) gene, with strong evidence pointing to a mechanistic link with the tRNA precursor processing defect. Such reduction significantly affects the rate of synthesis of the ND6 subunit and plays a determinant role in the deafness-associated respiratory phenotype of the mutant cell lines. In particular, it accounts for their specific, very significant decrease in glutamate- or malate-dependent O2 consumption. Furthermore, several homoplasmic mtDNA mutations affecting subunits of NADH dehydrogenase may play a synergistic role in the establishment of the respiratory phenotype of the mutant cells.

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

2020 ◽  
pp. 159-181
Author(s):  
Matthew Zorkau ◽  
Yasmin Proctor-Kent ◽  
Rolando Berlinguer-Palmini ◽  
Andrew Hamilton ◽  
Zofia M. Chrzanowska-Lightowlers ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Cell Lines ◽  
Ribosomal Rna ◽  
Human Cell ◽  
Mitochondrial Protein ◽  
Human Cell Lines ◽  
Mitochondrial Protein Synthesis

Effects of mycoplasma contamination on phenotypic expression of mitochondrial mutants in human cells

1981 ◽  
Vol 1 (4) ◽  
pp. 321-329
Author(s):  
C J Doersen ◽  
E J Stanbridge
Keyword(s):  
Protein Synthesis ◽  
Infected Cell ◽  
Cell Lines ◽  
Resistant Strain ◽  
Drug Sensitivity ◽  
Mitochondrial Protein ◽  
Phenotypic Expression ◽  
Mitochondrial Protein Synthesis ◽  
Protein Synthesis Inhibitors

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.

scholarly journals Mitonuclear Interactions in the Maintenance of Mitochondrial Integrity

Life ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 173
Author(s):  
Panagiotis Karakaidos ◽  
Theodoros Rampias
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Mitochondrial Genome ◽  
Aging Process ◽  
Mitochondrial Protein ◽  
Eukaryotic Cells ◽  
Mitochondrial Protein Synthesis ◽  
Respiratory Chain Complexes ◽  
Chain Complexes ◽  
Insight Into

In eukaryotic cells, mitochondria originated in an α-proteobacterial endosymbiont. Although these organelles harbor their own genome, the large majority of genes, originally encoded in the endosymbiont, were either lost or transferred to the nucleus. As a consequence, mitochondria have become semi-autonomous and most of their processes require the import of nuclear-encoded components to be functional. Therefore, the mitochondrial-specific translation has evolved to be coordinated by mitonuclear interactions to respond to the energetic demands of the cell, acquiring unique and mosaic features. However, mitochondrial-DNA-encoded genes are essential for the assembly of the respiratory chain complexes. Impaired mitochondrial function due to oxidative damage and mutations has been associated with numerous human pathologies, the aging process, and cancer. In this review, we highlight the unique features of mitochondrial protein synthesis and provide a comprehensive insight into the mitonuclear crosstalk and its co-evolution, as well as the vulnerabilities of the animal mitochondrial genome.

scholarly journals Effects of mycoplasma contamination on phenotypic expression of mitochondrial mutants in human cells.

1981 ◽  
Vol 1 (4) ◽  
pp. 321-329 ◽  
Author(s):  
C J Doersen ◽  
E J Stanbridge
Keyword(s):  
Protein Synthesis ◽  
Infected Cell ◽  
Cell Lines ◽  
Resistant Strain ◽  
Drug Sensitivity ◽  
Mitochondrial Protein ◽  
Phenotypic Expression ◽  
Mitochondrial Protein Synthesis ◽  
Protein Synthesis Inhibitors

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.

scholarly journals In vitro genetic transfer of protein synthesis and respiration defects to mitochondrial DNA-less cells with myopathy-patient mitochondria

1991 ◽  
Vol 11 (4) ◽  
pp. 2236-2244
Author(s):  
A Chomyn ◽  
G Meola ◽  
N Bresolin ◽  
S T Lai ◽  
G Scarlato ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Human Cell ◽  
Mitochondrial Myopathy ◽  
Mitochondrial Protein ◽  
Human Cell Lines ◽  
Mitochondrial Protein Synthesis ◽  
Direct Link ◽  
Genetic Transfer

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.

scholarly journals Reversible Inhibition of Mitochondrial Protein Synthesis during Linezolid-Related Hyperlactatemia

2006 ◽  
Vol 51 (3) ◽  
pp. 962-967 ◽  
Author(s):  
Glòria Garrabou ◽  
Alejandro Soriano ◽  
Sònia López ◽  
Jordi P. Guallar ◽  
Marta Giralt ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Mononuclear Cells ◽  
Intact Cell ◽  
Mitochondrial Protein ◽  
Mitochondrial Rna ◽  
Mitochondrial Protein Synthesis ◽  
Peripheral Blood Mononuclear ◽  
Mitochondrial Mass ◽  
Clinical Recovery

ABSTRACT The objective of the present study was to determine the mitochondrial toxicity mechanisms of linezolid-related hyperlactatemia. Five patients on a long-term schedule of linezolid treatment were studied during the acute phase of hyperlactatemia and after clinical recovery and lactate normalization following linezolid withdrawal. Mitochondrial studies were performed with peripheral blood mononuclear cells and consisted of measurement of mitochondrial mass, mitochondrial protein synthesis homeostasis (cytochrome c oxidase [COX] activity, COX-II subunit expression, COX-II mRNA abundance, and mitochondrial DNA [mtDNA] content), and overall mitochondrial function (mitochondrial membrane potential and intact-cell oxidative capacity). During linezolid-induced hyperlactatemia, we found extremely reduced protein expression (16% of the remaining content compared to control values [100%], P < 0.001) for the mitochondrially coded, transcribed, and translated COX-II subunit. Accordingly, COX activity was also found to be decreased (51% of the remaining activity, P < 0.05). These reductions were observed despite the numbers of COX-II mitochondrial RNA transcripts being abnormally increased (297%, P = 0.10 [not significant]) and the mitochondrial DNA content remaining stable. These abnormalities persisted even after the correction for mitochondrial mass, which was mildly decreased during the hyperlactatemic phase. Most of the mitochondrial abnormalities returned to control ranges after linezolid withdrawal, lactate normalization, and clinical recovery. Linezolid inhibits mitochondrial protein synthesis, leading to decreased mitochondrial enzymatic activity, which causes linezolid-related hyperlactatemia, which resolves upon discontinuation of linezolid treatment.

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