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Project description:Heteroplasmic pathogenic mitochondrial DNA (mtDNA) mutations are known to cause mitochondrial diseases with varied clinical symptoms. The tissue-specific selection of heteroplasmic pathogenic mtDNA mutations and its correlation with clinical and pathological outcomes remains to be elucidated. To date, negative selection of pathogenic mutations has been observed in a limited range of cell types, including female germ cells, blood cells, particularly T cells, and intestinal epithelial cells. However, evidence of positive selection in any tissue or cell type has not been reported. In this study, we utilized the DddA-derived cytosine base editor (DdCBE) technique to generate a heteroplasmic pathogenic mutant mouse model harboring a mutation in the mito-tRNA Glu anticodon arm site. Over a two-year longitudinal investigation, we assessed the mutational selection dynamics in eight solid organs and blood from this model. Our findings reveal a significant positive selection for pathogenic mtDNA in the kidney and liver. Notably, the kidney exhibited mitochondrial kidney disease during aging, reflecting the clinical kidney defects observed in patients with mito-tRNA mutations. Intriguingly, disparate selection patterns emerged within multiple cell types of kidneys, with tubular epithelial cells and podocytes presenting positive selection, whereas immune cells exhibited purifying selection. Leveraging Sc-RNA seq and Stereo-seq, we identified Clu and Spp1 as molecular markers of the high mutant kidney tubular epithelial cells and suggest that up-regulation of these markers may activate the p-AKT pathway, thereby increasing the proliferation of high mutant tubular epithelial cells, hence leads to the positive selection on this site in mutant kidneys during aging. Our comprehensive analysis provides compelling evidence for the significance of tissue-specific selection of pathogenic mtDNA mutations. This study enhances our understanding of the mechanistic links between tissue-specific selection and mitochondrial disease pathogenesis, paving the way for the development of targeted therapeutic strategies in the future.
2025-06-16 | GSE282115 | GEO
Project description:Heteroplasmic pathogenic mitochondrial DNA (mtDNA) mutations are known to cause mitochondrial diseases with varied clinical symptoms. The tissue-specific selection of heteroplasmic pathogenic mtDNA mutations and its correlation with clinical and pathological outcomes remains to be elucidated. To date, negative selection of pathogenic mutations has been observed in a limited range of cell types, including female germ cells, blood cells, particularly T cells, and intestinal epithelial cells. However, evidence of positive selection in any tissue or cell type has not been reported. In this study, we utilized the DddA-derived cytosine base editor (DdCBE) technique to generate a heteroplasmic pathogenic mutant mouse model harboring a mutation in the mito-tRNA Glu anticodon arm site. Over a two-year longitudinal investigation, we assessed the mutational selection dynamics in eight solid organs and blood from this model. Our findings reveal a significant positive selection for pathogenic mtDNA in the kidney and liver. Notably, the kidney exhibited mitochondrial kidney disease during aging, reflecting the clinical kidney defects observed in patients with mito-tRNA mutations. Intriguingly, disparate selection patterns emerged within multiple cell types of kidneys, with tubular epithelial cells and podocytes presenting positive selection, whereas immune cells exhibited purifying selection. Leveraging Sc-RNA seq and Stereo-seq, we identified Clu and Spp1 as molecular markers of the high mutant kidney tubular epithelial cells and suggest that up-regulation of these markers may activate the p-AKT pathway, thereby increasing the proliferation of high mutant tubular epithelial cells, hence leads to the positive selection on this site in mutant kidneys during aging. Our comprehensive analysis provides compelling evidence for the significance of tissue-specific selection of pathogenic mtDNA mutations. This study enhances our understanding of the mechanistic links between tissue-specific selection and mitochondrial disease pathogenesis, paving the way for the development of targeted therapeutic strategies in the future.
2025-06-16 | GSE282114 | GEO
Project description:Heteroplasmic pathogenic mitochondrial DNA (mtDNA) mutations are known to cause mitochondrial diseases with varied clinical symptoms. The tissue-specific selection of heteroplasmic pathogenic mtDNA mutations and its correlation with clinical and pathological outcomes remains to be elucidated. To date, negative selection of pathogenic mutations has been observed in a limited range of cell types, including female germ cells, blood cells, particularly T cells, and intestinal epithelial cells. However, evidence of positive selection in any tissue or cell type has not been reported. In this study, we utilized the DddA-derived cytosine base editor (DdCBE) technique to generate a heteroplasmic pathogenic mutant mouse model harboring a mutation in the mito-tRNA Glu anticodon arm site. Over a two-year longitudinal investigation, we assessed the mutational selection dynamics in eight solid organs and blood from this model. Our findings reveal a significant positive selection for pathogenic mtDNA in the kidney and liver. Notably, the kidney exhibited mitochondrial kidney disease during aging, reflecting the clinical kidney defects observed in patients with mito-tRNA mutations. Intriguingly, disparate selection patterns emerged within multiple cell types of kidneys, with tubular epithelial cells and podocytes presenting positive selection, whereas immune cells exhibited purifying selection. Leveraging Sc-RNA seq and Stereo-seq, we identified Clu and Spp1 as molecular markers of the high mutant kidney tubular epithelial cells and suggest that up-regulation of these markers may activate the p-AKT pathway, thereby increasing the proliferation of high mutant tubular epithelial cells, hence leads to the positive selection on this site in mutant kidneys during aging. Our comprehensive analysis provides compelling evidence for the significance of tissue-specific selection of pathogenic mtDNA mutations. This study enhances our understanding of the mechanistic links between tissue-specific selection and mitochondrial disease pathogenesis, paving the way for the development of targeted therapeutic strategies in the future.
2025-06-16 | GSE271868 | GEO
Project description:Age-dependent accumulation of mitochondrial tRNA mutations in mouse kidneys linked to mitochondrial kidney diseases
| PRJNA1187218 | ENA
Project description:Age-dependent accumulation of mitochondrial tRNA mutations in mouse kidneys linked to mitochondrial kidney diseases [mtscATAC-Seq]
| PRJNA1187220 | ENA
Project description:Age-dependent accumulation of mitochondrial tRNA mutations in mouse kidneys linked to mitochondrial kidney diseases [RNA-Seq]
| PRJNA1187219 | ENA
Project description:Age-dependent accumulation of mitochondrial tRNA mutations in mouse kidneys linked to mitochondrial kidney diseases [scRNA-Seq]
| PRJNA1133774 | ENA
Project description:Unknown processes promote the accumulation of mitochondrial DNA (mtDNA) mutations during aging. Accumulation of defective mitochondrial genomes is thought to promote the progression of heteroplasmic mitochondrial diseases and degenerative changes with natural aging. We used a heteroplasmic Drosophila model to test 1) whether purifying selection acts to limit the abundance of deleterious mutations during development and aging, 2) whether quality control pathways contribute to purifying selection, 3) whether activation of quality control can mitigate accumulation of deleterious mutations, and 4) whether improved quality control improves health span. We show that purifying selection operates during development and growth but is ineffective during aging. Genetic manipulations suggest that a quality control process known to enforce purifying selection during oogenesis also suppresses accumulation of a deleterious mutation during growth and development. Flies with nuclear genotypes that enhance purifying selection sustained higher genome quality, retained more vigorous climbing activity, and lost fewer dopaminergic neurons. A pharmacological agent thought to enhance quality control produced similar benefits. Importantly, similar pharmacological treatment of aged mice reversed age-associated accumulation of a deleterious mtDNA mutation. Our findings reveal dynamic maintenance of mitochondrial genome fitness and reduction in the effectiveness of purifying selection during life. Importantly, we describe interventions that mitigate and even reverse age-associated genome degeneration in flies and in mice. Furthermore, mitigation of genome degeneration improved well-being in a Drosophila model of heteroplasmic mitochondrial disease.
| S-EPMC9351377 | biostudies-literature
Project description:During tRNA maturation in yeast, aberrant pre-tRNAs are targeted for 3'-5' degradation by the nuclear surveillance pathway, and aberrant mature tRNAs are targeted for 5'-3' degradation by the rapid tRNA decay (RTD) pathway. RTD is catalyzed by the 5'-3' exonucleases Xrn1 and Rat1, which act on tRNAs with an exposed 5' end due to the lack of certain body modifications or the presence of destabilizing mutations in the acceptor stem, T-stem, or tRNA fold. RTD is inhibited by mutation of MET22, likely due to accumulation of the Met22 substrate adenosine 3',5' bis-phosphate, which inhibits 5'-3' exonucleases. Here we provide evidence for a new tRNA quality control pathway in which intron-containing pre-tRNAs with destabilizing mutations in the anticodon stem are targeted for Met22-dependent pre-tRNA decay (MPD). Multiple SUP4οc anticodon stem variants that are subject to MPD each perturb the bulge-helix-bulge structure formed by the anticodon stem-loop and intron, which is important for splicing, resulting in substantial accumulation of end-matured unspliced pre-tRNA as well as pre-tRNA decay. Mutations that restore exon-intron structure commensurately reduce pre-tRNA accumulation and MPD. The MPD pathway can contribute substantially to decay of anticodon stem variants, since pre-tRNA decay is largely suppressed by removal of the intron or by restoration of exon-intron structure, each also resulting in increased tRNA levels. The MPD pathway is general as it extends to variants of tRNATyr(GUA) and tRNASer(CGA) These results demonstrate that the integrity of the anticodon stem-loop and the efficiency of tRNA splicing are monitored by a quality control pathway.
| S-EPMC6913130 | biostudies-literature
Project description:GTPBP3 and MTO1 cooperatively catalyze 5-taurinomethyluridine (τm5U) biosynthesis at the 34th wobble position of mitochondrial tRNAs. Mutations in tRNAs, GTPBP3 or MTO1, causing τm5U hypomodification, lead to various diseases. However, efficient in vitro reconstitution and mechanistic study of τm5U modification have been challenging, in part due to the lack of pure and active enzymes. A previous study reported that purified human GTPBP3 (hGTPBP3) is inactive in GTP hydrolysis. Here, we identified the mature form of hGTPBP3 and showed that hGTPBP3 is an active GTPase in vitro that is critical for tRNA modification in vivo. Unexpectedly, the isolated G domain and a mutant with the N-terminal domain truncated catalyzed GTP hydrolysis to only a limited extent, exhibiting high Km values compared with that of the mature enzyme. We further described several important pathogenic mutations of hGTPBP3, associated with alterations in hGTPBP3 localization, structure and/or function in vitro and in vivo. Moreover, we discovered a novel cytoplasm-localized isoform of hGTPBP3, indicating an unknown potential noncanonical function of hGTPBP3. Together, our findings established, for the first time, the GTP hydrolysis mechanism of hGTPBP3 and laid a solid foundation for clarifying the τm5U modification mechanism and etiology of τm5U deficiency-related diseases.
| S-EPMC7969015 | biostudies-literature