Hybrid lizards with introgressed mtDNA show resistance to DNA damage from Reactive Oxygen Species
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ABSTRACT:
PROVIDER: PRJNA1077356 | ENA |
REPOSITORIES: ENA
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Project description:Hybrids can experience genetic incompatibilities that lead to cellular dysfunction and infertility. Previous analyses of mitochondrial function in the lizards Urosaurus graciosus and Urosaurus ornatus found that hybrids, which had introgressed mtDNA, experienced higher ATP production which increases reactive oxygen species (ROS) production, one of the main causes of damage to DNA. Hybrid populations of these lizards have persisted so we predicted they may have mechanisms for protecting their DNA from damage. To test this, we exposed liver cells of these lizards to hydrogen peroxide, a source of ROS, and compared DNA damage using single-cell gel electrophoresis. Hybrid cells showed significantly less DNA damage. We then examined potential mechanisms to explain this result by comparing melanin content of livers and expression levels of antioxidant genes. If functioning to deal with ROS, these should be expressed higher in hybrids. Melanin content of livers was highly variable among U. graciosus individuals and therefore not highest in hybrids as expected. Eighteen antioxidant genes showed significant differential expression but were not expressed consistently higher in hybrids. The overall gene expression profiles of hybrids and U. graciosus were very similar while that of the mtDNA donor species, U. ornatus, was highly divergent from both. Three antioxidant genes with different expression levels in hybrids and that warrant further study were SOD2, SOD3, and PRDX2. These results show how species can compensate for mtDNA introgression and highlight the complexity of genetic interactions encountered when closely related species exchange genetic material in zones of secondary contact.
2025-06-23 | GSE255990 | GEO
Project description:Restriction site-associated DNA markers of Australian lizards
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Project description:Most humans carry a mixed population of mitochondrial DNA (mtDNA heteroplasmy) affecting ~1-2% of molecules, but rapid percentage shifts occur over one generation leading to severe mitochondrial diseases. A decrease in the amount of mtDNA within the developing female germ line appears to play a role, but other sub-cellular mechanisms have been implicated. Establishing an in vitro model of early mammalian germ cell development from embryonic stem cells, here we show the reduction of mtDNA content is modulated by oxygen and reaches a nadir immediately before germ cell specification. The observed genetic bottleneck was accompanied by a decrease in mtDNA replicating foci and the segregation of heteroplasmy, which were both abolished at higher oxygen levels. Thus, differences in oxygen tension during early development can modulate mtDNA segregation, facilitating germ-line purification, and contribute to tissue-specific somatic mutation loads.
2021-05-19 | GSE169427 | GEO
Project description:Regulator of chromosome condensation domain-containing protein 1 (RCCD1) plays an important role in chromosome segregation and microtubule stability in the nucleus and has been identified recently as a potential driver for breast cancer. We report here that, unexpectedly, RCCD1 is also localized in mitochondria. We show that RCCD1 resides in the mitochondrial inner membrane, where it interacts with the mitochondrial contact site/cristae organizing system (MICOS) and mitochondrial DNA (mtDNA) to regulate mitochondrial nucleoid organization, thereby influencing mtDNA transcription, oxidative phosphorylation, and the production of reactive oxygen species. Interestingly, RCCD1 is upregulated under hypoxic conditions, leading to decreased generation of reactive oxygen species and alleviated apoptosis favoring cancer cell survival. We show that RCCD1 promotes breast cancer cell proliferation in vitro and accelerates breast tumor growth in vivo. Indeed, RCCD1 is overexpressed in breast carcinomas, and its level of expression is associated with aggressive breast cancer phenotypes and poor patient survival. Our study reveals an additional dimension in RCCD1 functionality, indicating RCCD1 is an essential regulator of mtDNA dynamics and mitochondrial homeostasis, whose dysregulation inflicts pathologic states such as breast cancer.
2023-12-01 | GSE219134 | GEO
Project description:Expression analysis of cells the given amount of time after mtDNA was lost (or Nar1 expression was repressed) compared to pretreatment (or NAR1 being fully expressed). One time course experiment (Cells a given amount of time following mtDNA loss compared to cells with intact mtDNA), with 2 two condition experiments (Cells with the ATP1-111 genotype 27 hours following mtDNA loss compared to the same cells with intact mtDNA, and cells 27 hours following repression of NAR1 comared to cells expressing NAR1). Each data point had 3 biological replicates, and was dye-swapped. One replicate per array.
2010-06-21 | E-GEOD-15302 | biostudies-arrayexpress
Project description:The exact in vivo role for RNase H1 in mammalian mitochondria (mtDNA) has been much debated and we show here that it is essential for processing of RNA primers to provide site-specific initiation of mtDNA replication. Without RNase H1, mtDNA replication is instead initiated at non-canonical sites and becomes impaired. Furthermore, RNase H1 is also needed for replication completion and in its absence linear deleted mtDNA molecules extending between the two origins of mtDNA replication are formed. Finally, we report the first patient with a homozygous pathogenic mutation in the hybrid-binding domain (HBD) of RNase H1 causing impaired mtDNA replication. In contrast to catalytically dead pathological variants of RNase H1, this mutant version has enhanced enzyme activity. This finding shows that the RNase H1 activity must be strictly controlled to allow proper regulation of mtDNA replication.
2022-07-13 | GSE199198 | GEO
Project description:Integrity of mitochondrial DNA (mtDNA), encoding several subunits of the respiratory chain, is essential to maintain mitochondrial fitness. Mitochondria, as a central hub for metabolism, are affected in a wide variety of human diseases but also during normal ageing, where mtDNA integrity is compromised. Mitochondrial quality control mechanisms work at different levels, and mitophagy and its variants are critical to remove dysfunctional mitochondria and mtDNA to maintain cellular homeostasis. Understanding the mechanisms governing a selective turnover of mutation-bearing mtDNA without affecting the entire mitochondrial pool is fundamental to design therapeutic strategies against mtDNA diseases and ageing. Here, we show that mtDNA damage after expressing a dominant negative version of the mitochondrial helicase Twinkle, or by chemical means, leads to an exacerbated mtDNA turnover. mtDNA removal depends on lysosomal function and requires the autophagy protein Atg5 but is independent of canonical mitophagy or autophagy. Using proximity labelling, we demonstrated that the area of influence of mitochondrial nucleoids differs upon mtDNA damage, which induces mitochondrial membrane remodelling and endosomal recruitment in close proximity to mitochondrial nucleoid sub compartments. Targeting of nucleoids is controlled by the mitochondrial transmembrane proteins ATAD3 and SAMM50, which together with the endosomal trafficking protein VPS35, orchestrate endosomal nucleoid engulfment. SAMM50 acts as a gatekeeper to avoid mtDNA release to the cytoplasm and facilitating mtDNA transfer to VPS35. Lastly, we show that stimulation of lysosomal activity by rapamycin selectively removes mtDNA deletions in vivo, without affecting mtDNA copy number. With these results, we unveil the molecular players of a new complex mechanism specifically targeting and removing mutant mtDNA which occurs outside the mitochondrial network, a process with multiple potential benefits to understand human mtDNA related diseases, either inherited, acquired or due to normal ageing.
2022-11-07 | PXD023939 | Pride