Project description:We report mitochondrial genome (mtDNA) sequences in purified mouse muscle stem cells at different ages. This study identifies changes in the mitochondrial genome of muscle stem cells during aging.
Project description:Mitochondria have an independent genome (mtDNA) and protein synthesis machinery that coordinately activate for mitochondrial generation. Here, we report that Krebs cycle intermediate, fumarate, connects metabolism to mitobiogenesis through binding to malic enzyme 2 (ME2). Proteomic profiling of ME2-interacting protein reveals that ME2 binds to mitoribosome proteins to regulate mitoribosome assembly and mtDNA-encoded protein production. ME2 also interacts with and modulates deoxyuridine 5-triphosphate nucleotidohydrolase activity to regulate thymidine generation and mtDNA abundance
Project description:Background: Cell free DNA (cfDNA) in plasma has received increasing attention and has been studied in a broad range of clinical conditions implicating inflammation, cancer, and aging. However, few studies have focused on mitochondrial DNA (mtDNA) in the cell free form. This study characterized the size distribution and sequence characteristics of plasma cell free mtDNA (cf mtDNA) in humans.Methods and Results: We optimized DNA isolation and next-generation sequencing library preparation protocols to better retain short DNA fragments from plasma, and applied these optimized methods to plasma samples from patients with sepsis. After massive parallel sequencing, we verified that our methods can retain substantially shorter DNA fragments than the standard isolation method, resulting in an average of 11.5 fold increase in short DNA fragments yield (DNA < 100bp). We report that cf mtDNA in plasma is highly enriched in short-size cfDNA (30 ~ 60 bp), which is much shorter than the value previously reported (~140 bp). Motivated by this unique size distribution, we size-selected short cfDNA fragments from the sequencing library, which further increased the mtDNA recovery rate by an average of 10.4 fold. Using this approach we detected mixtures of different mtDNA sequences, termed heteroplasmy, in plasma from 3 patients. In one patient who previously received bone marrow transplantation, different minor allele frequencies were observed between plasma and white blood cells (WBC) at heteroplasmic mtDNA sites, consistent with mixed-tissue origin for plasma DNA.Conclusion: mtDNA in plasma exists as very short fragments that exhibit mtDNA heteroplasmy distribution differences from that found in a single organ/tissue. This study is the first report of genome wide identification of mtDNA heteroplasmy in human plasma. Our optimized method can be used to investigate the potential utility of cf mtDNA fragments and heteroplasmy as biomarkers in various diseases.
Project description:<p><em>Tripterygium wilfordii</em> is a vine used in Traditional Chinese Medicine (TCM) from the family Celastraceae. The active ingredient celastrol is a friedelane-type pentacyclic triterpenoid, with a putative role as an anti-tumor, immunosuppression, and obesity agent. Here we reported a reference genome assembly of <em>T. wilfordii</em> with high-quality annotation by using a hybrid sequencing strategy, which obtained a 340.12 Mb total genome size, a contig N50 reaching 3.09 Mb, 31593 structure genes, and the repeat percentage was 44.31%. Comparative evolutional analyses showed that <em>T. wilfordii</em> diverged from species of Malpighiales about 102.4 million years ago. In addition, we successfully anchored 91.02% sequences into 23 pseudochromosomes using Hi-C technology and the super-scaffold N50 reached 13.03 Mb. Based on integration of genome, transcriptome and metabolite analyses, as well as in vivo and in vitro enzyme assays of the two CYP450 genes, <em>TwCYP712K1</em> and <em>TwCYP712K2</em> the second biosynthesis step of celastrol was investigated and elucidated. Syntenic analysis revealed that <em>TwCYP712K1</em> and <em>TwCYP712K2</em> derived from a common ancestor. These results have provided insights into further investigating pathways for celastrol and valuable information to aid the conservation of resources and helped us reveal the evolution of Celastrales.</p>
Project description:Diet may be modified seasonally or by biogeographic, demographic or cultural shifts. It can differentially influence mitochondrial bioenergetics, retrograde signalling to the nuclear genome, and anterograde signalling to mitochondria. All these interactions have the potential to influence the frequencies of mtDNA types in nature and human health. In a model laboratory system, we fed four diets varying in Protein: Carbohydrate (P:C) ratio (1:2, 1:4, 1:8 and 1:16 P:C) to four Drosophila mitotypes and assayed their frequency in population cages. The nuclear genome was standardised. When fed a high protein 1:2 P:C diet, the frequency of flies harbouring Alstonville mtDNA increased. In contrast, when fed the high carbohydrate 1:16 P:C food the incidence of flies harbouring Dahomey mtDNA increased. This result was repeated when the laboratory diet was replaced by natural fruits having high and low P:C ratios and when the nuclear genome was permuted. Quaternary structural modelling, in vitro assays of electron transport chain protein complexes, and protein gels suggested a V161L mutation in the ND4 subunit of Complex I of Dahomey mtDNA was functionally deleterious and resulted in an increase in larval development time on the 1:2 P:C diet. Conversely, the 1:16 P:C diet resulted in an elegant remodelling of energy metabolism and relative reduction in development time of larvae harbouring Dahomey mtDNA. These data question the use of mtDNA as an assumed neutral maker. We posit that humans with specific mtDNA variations may differentially metabolise carbohydrates, which has implications for a variety of first-world diseases including cardiovascular disease, diabetes, obesity and perhaps Parkinson’s Disease.
Project description:More than 2x10E9 sequences made on Illumina platform derived from the genome of E14 embryonic stem cells cultured in our laboratory were used to build a database of about 2.7x10E6 single nucleotide variant. The database was validated using other two sequencing datasets from other laboratory and high overlap was observed. The identified variant are enriched on intergenic regions, but several thousands reside on gene exons and regulatory regions, such as promoters, enhancers, splicing site and untranslated regions of RNA, thus indicating high probability of an important functional impact on the molecular biology of this cells. We created a new E14 genome assembly including the new identified variants and used it to map reads from next generation sequencing data generated in our laboratory or in others on E14 cell line. We observed an increase in the number of mapped reads of about 5%. CpG dinucleotide showed the higher variation frequency, probably because of it could be target of DNA methylation. We performed a reduced representation bisulfite sequencing on E14 cell line to test our new genome assembly with respect to the mm9 genome reference. After mapping and methylation status calling, we obtained an increase of about 120,000 called CpG and we avoided about 20,000 wrong CpG calling. genotyping of E14 embryonic stem cells (ESCs) and Reduced representation Bisulfite Sequencing (RRBS) of E14 ESCs.
Project description:Mitochondrial DNA (mtDNA) damage is considered as a possible primary cause of Parkinson’s disease (PD). To explore the issue, mtDNA sequences from whole blood were analyzed in PD patients and controls using a resequencing chip and allelic substitutions were estimated for each nucleotide position (np) along the entire mtDNA sequence. Overall, 58 np showed a different allelic distribution in the two groups; of these, 81% showed an increase of non-reference alleles in PD patients, similar to findings reported in patients with Alzheimer’s disease, albeit in reduced proportion. These results suggest that age-related neurodegenerative diseases could share a mechanism involving mtDNA.