Regulation of Mother-to-Offspring Transmission of mtDNA Heteroplasmy

Latorre‐Pellicer, Ana; Lechuga‐Vieco, Ana Victoria; Johnston, Iain G.; Hämäläinen, Riikka H.; Pellico, Juan; Justo-Méndez, Raquel; Fernández-Toro, Jose María; Claverı́a, Cristina; Guarás, Adela; Sierra, Rocío; Llop, Jordi; Torres, Miguel; Criado, Luis M.; Suomalainen, Anu; Jones, Nick; Ruı́z-Cabello, Jesús; Enríquez, José Antonio

doi:10.1016/j.cmet.2019.09.007

Cited by 73 publications

(93 citation statements)

References 49 publications

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“…To attempt to extend this result for ρ+ mutant cells, we used two independent ρ+ recipient cybrid cells generated with different nuclear and mitochondrial DNA origins. A recent study showed that nucleus-mitochondrial genome (mtDNA-nDNA) interactions control mtDNA heteroplasmy 47 . Therefore, we tested whether recipient cells with mismatched or matched endogenous mtDNA-nDNA pair origins integrate exogenous mtDNA.…”

Section: Resultsmentioning

confidence: 99%

Stable retention of chloramphenicol-resistant mtDNA to rescue metabolically impaired cells

Dawson

Patananan

Sercel

et al. 2020

Sci Rep

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The permanent transfer of specific mtDNA sequences into mammalian cells could generate improved models of mtDNA disease and support future cell-based therapies. Previous studies documented multiple biochemical changes in recipient cells shortly after mtDNA transfer, but the long-term retention and function of transferred mtDNA remains unknown. Here, we evaluate mtDNA retention in new host cells using 'MitoPunch', a device that transfers isolated mitochondria into mouse and human cells. We show that newly introduced mtDNA is stably retained in mtDNA-deficient (ρ0) recipient cells following uridine-free selection, although exogenous mtDNA is lost from metabolically impaired, mtDNA-intact (ρ+) cells. We then introduced a second selective pressure by transferring chloramphenicol-resistant mitochondria into chloramphenicol-sensitive, metabolically impaired ρ+ mouse cybrid cells. Following double selection, recipient cells with mismatched nuclear (nDNA) and mitochondrial (mtDNA) genomes retained transferred mtDNA, which replaced the endogenous mutant mtDNA and improved cell respiration. However, recipient cells with matched mtDNA-nDNA failed to retain transferred mtDNA and sustained impaired respiration. Our results suggest that exogenous mtDNA retention in metabolically impaired ρ+ recipients depends on the degree of recipient mtDNA-nDNA co-evolution. Uncovering factors that stabilize exogenous mtDNA integration will improve our understanding of in vivo mitochondrial transfer and the interplay between mitochondrial and nuclear genomes. Mutations in the multi-copy mitochondrial genome (mtDNA) can impair the biosynthesis of ATP, metabolites, fatty acids, reactive oxygen species, and iron sulfur clusters 1-4. Even a single nucleotide polymorphism can have profound effects on cellular function and contribute to pathologies including cardiomyopathies, diabetes, autoimmune diseases, neurological disorders, cancer, and even aging 5,6. The degree of pathology often depends on the ratio of mutant to wild-type mtDNA populations within the same cell, a situation known as heteroplasmy 7. One in 5,000 people have some degree of a pathological mtDNA disorder, and up to 1 in 8 individuals carry low levels of a mtDNA mutation that can be inherited through the maternal germline 8-11. Mitochondrial replacement therapy (MRT) aims to prevent transmission of mtDNA disorders from affected mothers to offspring, but limited treatments exist for those already living with a pathological mtDNA mutation 12,13. Our ability to repair mutant mtDNA and improve metabolically impaired cells would advance disease modeling studies and potential cell-based therapies for mtDNA disorders. Gene therapy and now gene editing is a viable treatment option for some nucleus-encoded disorders 5,14,15. In contrast, specific mtDNA mutations are difficult to generate or repair because current gene modifying approaches do not work well inside mitochondria.

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Section: Resultsmentioning

confidence: 99%

Stable retention of chloramphenicol-resistant mtDNA to rescue metabolically impaired cells

Dawson

Patananan

Sercel

et al. 2020

Sci Rep

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“…However, as the mutation rate of mtDNA is significantly higher than that of nuclear DNA (Allio et al, 2017; Khrapko et al, 1997) this increased replication most likely leads to an increased mutation load. A number of mechanisms have been proposed to reduce this mutation load, such as the bottleneck effect, purifying selection or biased segregation of mtDNA haplotypes (Burgstaller et al, 2014; Johnston et al, 2015; Latorre-Pellicer et al, 2019; Lee et al, 2012; Sharpley et al, 2012; Zhang et al, 2018). However, despite these mechanisms, inheritable mtDNA based diseases are reported with a prevalence of 5-15 cases per 100,000 individuals (Burgstaller et al, 2015; Gorman et al, 2016), highlighting both the importance and limitations of these selection mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Cell competition acts as a purifying selection to eliminate cells with mitochondrial defects during early mouse development

Lima

Lubatti

Burgstaller

et al. 2020

Preprint

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Cell competition is emerging as a quality control mechanism that eliminates unfit cells in a wide range of settings from development to the adult. However, the nature of the cells normally eliminated by cell competition and what triggers their elimination remains poorly understood. Here we have performed single cell transcriptional profiling of early mouse embryos and find that the cells eliminated show the hallmarks of cell competition, are mis-patterned and have mitochondrial defects. We demonstrate that mitochondrial defects are common to a range of different loser cell types and that manipulating mitochondrial function is sufficient to trigger competition. Importantly, we show that in the embryo loser epiblast cells display mitochondrial DNA mutations and that even small changes in mitochondrial DNA sequence can influence the competitive ability of the cell.Our results therefore suggest that cell competition is a purifying selection that optimises metabolic output prior to gastrulation. Running title: Cell competition and mitochondrial selectionDuring the early stages of mammalian development, the cellular and molecular landscape is 2 profoundly remodelled. As embryonic cells approach gastrulation, when the precursors of all 3 embryonic tissues are specified, they need to rewire the transcriptional, epigenetic, metabolic and 4 signalling networks that govern cell identity (Kojima et al., 2014). These changes are accompanied 5 by a marked acceleration in the proliferation rate (Snow, 1977) and need to be orchestrated with 6 the different morphogenetic processes that re-shape the embryo (reviewed in (Stower and 7 Srinivas, 2018). The scale of this remodelling creates the potential for the emergence of abnormal 8 cells that need to be removed to prevent them from contributing to the soma or germline during 9 development. This requirement implies that there must be stringent cell fitness quality control 10 mechanisms acting around the time of gastrulation. One such control has been postulated to be 11 cell competition, a fitness sensing mechanism eliminating cells that, although viable, are less fit 12 than their neighbours (reviewed in (Bowling et al., 2019; Diaz-Diaz and Torres, 2019; Madan et 13 al., 2018). During cell competition, the cells that are eliminated are generically termed losers, while 14 the fitter cells that survive are referred to as winners. 15Cell competition has been primarily studied in Drosophila, where it was first described in the cell RNA sequencing (scRNA-seq). To ensure we can capture the eliminated cells, as we have 70 done before (Bowling et al., 2018), we isolated embryos at E5.5 and cultured them for 16 hours in 71 the presence of a caspase inhibitors (CI) or vehicle (DMSO) ( Figure 1A and Figure S1A). 72Unsupervised clustering of the scRNA-seq data revealed five clusters: two corresponding to extra-73 embryonic tissues (visceral endoderm and extra-embryonic ectoderm) and three that expressed 74 epiblast marker genes (Figure 1B-C and Figure S1B-D). Interestingly, cells from CI...

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“…To fully understand the pathogenic mechanisms of mitochondrial diseases, it is also necessary to remind the key differences between the Mendelian rules governing nDNA genetics and the mtDNA genetics, which essentially is a population genetics of a multicopy genome [7,12]. Key mtDNA features in this respect include the following: Maternal inheritance of mtDNA [19], despite some debate on exceptions to this rule [20,21] The homoplasmy/heteroplasmy of mtDNA according to a homogenous sequence or to coexisting different sequences and its segregation in somatic tissues and in the germline [22,23] The threshold effect implicating a certain amount of mutant sequences necessary to induce a mitochondrial dysfunction that may vary in a mosaic cellular pattern from tissue to tissue [12] The high mutational rate and frequent fixation of sequence variants under different levels of selection [24], which ultimately shapes the population‐specific mtDNA haplogroups [25]. …”

Section: Introductionmentioning

confidence: 99%

Mitochondrial diseases in adults

et al. 2020

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Mitochondrial medicine is a field that expanded exponentially in the last 30 years. Individually rare, mitochondrial diseases as a whole are probably the most frequent genetic disorder in adults. The complexity of their genotype–phenotype correlation, in terms of penetrance and clinical expressivity, natural history and diagnostic algorithm derives from the dual genetic determination. In fact, in addition to the about 1.500 genes encoding mitochondrial proteins that reside in the nuclear genome (nDNA), we have the 13 proteins encoded by the mitochondrial genome (mtDNA), for which 22 specific tRNAs and 2 rRNAs are also needed. Thus, besides Mendelian genetics, we need to consider all peculiarities of how mtDNA is inherited, maintained and expressed to fully understand the pathogenic mechanisms of these disorders. Yet, from the initial restriction to the narrow field of oxidative phosphorylation dysfunction, the landscape of mitochondrial functions impinging on cellular homeostasis, driving life and death, is impressively enlarged. Finally, from the clinical standpoint, starting from the neuromuscular field, where brain and skeletal muscle were the primary targets of mitochondrial dysfunction as energy‐dependent tissues, after three decades virtually any subspecialty of medicine is now involved. We will summarize the key clinical pictures and pathogenic mechanisms of mitochondrial diseases in adults.

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Regulation of Mother-to-Offspring Transmission of mtDNA Heteroplasmy

Cited by 73 publications

References 49 publications

Stable retention of chloramphenicol-resistant mtDNA to rescue metabolically impaired cells

Stable retention of chloramphenicol-resistant mtDNA to rescue metabolically impaired cells

Cell competition acts as a purifying selection to eliminate cells with mitochondrial defects during early mouse development

Mitochondrial diseases in adults

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