Amount Of Mitochondrial DNA Research Articles

MitoQuicLy: A high-throughput method for quantifying cell-free DNA from human plasma, serum, and saliva

Circulating cell-free mitochondrial DNA (cf-mtDNA) is an emerging biomarker of psychobiological stress and disease which predicts mortality and is associated with various disease states. To evaluate the contribution of cf-mtDNA to health and disease states, standardized high-throughput procedures are needed to quantify cf-mtDNA in relevant biofluids. Here, we describe MitoQuicLy: Mitochondrial DNA Quantification in cell-free samples by Lysis. We demonstrate high agreement between MitoQuicLy and the commonly used column-based method, although MitoQuicLy is faster, cheaper, and requires a smaller input sample volume. Using 10 µL of input volume with MitoQuicLy, we quantify cf-mtDNA levels from three commonly used plasma tube types, two serum tube types, and saliva. We detect, as expected, significant inter-individual differences in cf-mtDNA across different biofluids. However, cf-mtDNA levels between concurrently collected plasma, serum, and saliva from the same individual differ on average by up to two orders of magnitude and are poorly correlated with one another, pointing to different cf-mtDNA biology or regulation between commonly used biofluids in clinical and research settings. Moreover, in a small sample of healthy women and men (n = 34), we show that blood and saliva cf-mtDNAs correlate with clinical biomarkers differently depending on the sample used. The biological divergences revealed between biofluids, together with the lysis-based, cost-effective, and scalable MitoQuicLy protocol for biofluid cf-mtDNA quantification, provide a foundation to examine the biological origin and significance of cf-mtDNA to human health.

Genome transfer technique for bovine embryo production using the metaphase plate and polar body.

Despite many studies in humans and mice using genome transfer (GT), there are few reports using this technique in oocytes of wild or domestic animals. Therefore, we aimed to establish a GT technique in bovine oocytes using the metaphase plate (MP) and polar body (PB) as the sources of genetic material. In the first experiment, GT was established using MP (GT-MP), and a sperm concentration of 1 × 106 or 0.5 × 106 spermatozoa/ml gave similar fertilization rates. The cleavage rate (50%) and blastocyst rate (13.6%) in the GT-MP group was lower than that of the in vitro production control group (80.2% and 32.6%, respectively). The second experiment evaluated the same parameters using PB instead of MP; the GT-PB group had lower fertilization (82.3% vs. 96.2%) and blastocyst (7.7% vs. 36.8%) rates than the control group. No differences in the amount of mitochondrial DNA (mtDNA) were observed between groups. Finally, GT-MP was performed using vitrified oocytes (GT-MPV) as a source of genetic material. The cleavage rate of the GT-MPV group (68.4%) was similar to that of the vitrified oocytes (VIT) control group (70.0%) and to that of the control IVP group (81.25%, P < 0.05). The blastocyst rate of GT-MPV (15.7) did not differ neither from the VIT control group (5.0%) nor from the IVP control group (35.7%). The results suggested that the structures reconstructed by the GT-MPV and GT-PB technique develop in embryos even if vitrified oocytes are used.

Impact of genetically predicted characterization of mitochondrial DNA quantity and quality on osteoarthritis.

Background: Existing studies have indicated that mitochondrial dysfunction may contribute to osteoarthritis (OA) development. However, the causal association between mitochondrial DNA (mtDNA) characterization and OA has not been extensively explored. Methods: Two-sample Mendelian randomization was performed to calculate the impact of mitochondrial genomic variations on overall OA as well as site-specific OA, with multiple analytical methods inverse variance weighted (IVW), weighted median (WM), MR-Egger and MR-robust adjusted profile score (MR-RAPS). Results: Genetically determined mitochondrial heteroplasmy (MtHz) and mtDNA abundance were not causally associated with overall OA. In site-specific OA analyses, the causal effect of mtDNA abundance on other OA sites, including hip, knee, thumb, hand, and finger, had not been discovered. There was a suggestively protective effect of MtHz on knee OA IVW OR = 0.632, 95% CI: 0.425-0.939, p-value = 0.023. No causal association between MtHz and other different OA phenotypes was found. Conclusion: MtHz shows potential to be a novel therapeutic target and biomarker on knee OA development. However, the variation of mtDNA abundance was measured from leukocyte in blood and the levels of MtHz were from saliva samples rather than cartilage or synovial tissues. Genotyping samples from synovial and cartilage can be a focus to further exploration.

Abstract PR016: Carcinoma-associated mesenchymal stem cells promote ovarian cancer metastasis by increasing tumor heterogeneity through direct mitochondrial transfer

Abstract Ovarian cancer is characterized by early, diffuse metastatic spread with most women presenting with widespread abdominal metastasis at the time of diagnosis. Prior work demonstrates carcinoma-associated mesenchymal stem cells (CA-MSCs) enhance ovarian cancer metastasis through a process of direct cellular interaction and formation of heterocellular CA-MSC and tumor cell complexes. Here we demonstrate CA-MSCs enhance metastasis via increasing tumor cell heterogeneity through mitochondrial donation. CA-MSCs directly interact with ovarian cancer cells forming tunneling nanotubules (TNTs). CA-MSCs transfer live mitochondria via these TNTs to ovarian cancer cells. This mitochondrial donation preferentially occurs in ovarian cancer cells with the least endogenous mitochondria (‘mito poor’ cancer cells). Mito poor cancer cells demonstrate decreased proliferation, increased sensitivity to chemotherapy and decreased oxidative phosphorylation compared to ‘mito rich’ cancer cells. CA-MSCs rescue the phenotype of these mito poor cancer cells restoring their proliferative capacity, increasing chemotherapy resistance and increasing oxidative phosphorylation. We validated these findings in a fully autologous system using CA-MSCs and cancer cells derived from the same patient to prevent confounding effects of cellular response to foreign organelle/DNA. Using a knockdown of the mitochondrial motor protein, MIRO1, we demonstrate mitochondrial transfer is necessary for the CA-MSC-mediated rescue of mito poor cancer cells. We developed a haplotype-specific quantification of mitochondrial DNA to differentiate CA-MSC derived mitochondria from endogenous tumor cell mitochondria. We used this system to both quantify the amount of CA-MSC mitochondrial donation and to demonstrate CA-MSC donated mitochondria persist in tumor cells over at least 14 days. Importantly, CA-MSC mitochondrial donation occurs in vivo and is associated with decreased survival in an orthotopic ovarian cancer mouse model. A DNA barcoding system was used to quantify tumor cell clonal heterogeneity. Using this system, we demonstrate CA-MSCs significantly enhance tumor cell heterogeneity, particularly during metastasis. This increase in tumor cell heterogeneity is dependent on CA-MSC mitochondrial transfer. Collectively, we report CA-MSC mitochondrial transfer as a critical mediator of ovarian cancer survival, heterogeneity and metastasis representing a potentially powerful therapeutic target. Citation Format: Leonard G. Frisbie, Catherine A. Pressimone, Huda I. Atiya, Alexander T. Pearson, Lan G. Coffman. Carcinoma-associated mesenchymal stem cells promote ovarian cancer metastasis by increasing tumor heterogeneity through direct mitochondrial transfer [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR016.

Low copy numbers for mitochondrial DNA moderates the strength of nuclear-cytoplasmic incompatibility in plants.

Plant cells contain only small amounts of mitochondrial DNA (mtDNA), with the genomic information shared among multiple mitochondria. The biological relevance and molecular mechanism underlying this hallmark of plant cells has been unclear. Here, we report that Arabidopsis thaliana plants exhibited significantly reduced growth and mitochondrial dysfunction when the mtDNA copy number was increased to the degree that each mitochondrion possessed DNA. The amounts of mitochondrion-encoded transcripts increased several fold in the presence of elevated mtDNA levels. However, the efficiency of RNA editing decreased with this excess of mitochondrion-encoded transcripts, resulting in impaired assembly of mitochondrial complexes containing mtDNA-encoded subunits, such as respiratory complexes I and IV. These observations indicate the occurrence of nuclear-mitochondrial incompatibility in the cells with increased amounts of mtDNA and provide an initial answer to the fundamental question of why plant cells have much lower mtDNA levels than animal cells. We propose that keeping mtDNA levels low moderates nuclear-mitochondrial incompatibility and that this may be a crucial factor driving plant cells to restrict the copy numbers of mtDNA.

Multidrug resistance transporter-1 dysfunction perturbs meiosis and Ca2+ homeostasis in oocytes.

Oocyte quality remains the most important and unsolved issue in reproduction. Our data show that multidrug resistance transporters and oocyte mitochondria are involved in determining oocyte quality in a mouse model. Multidrug resistance transporter-1 (MDR-1) is a transmembrane ATP-dependent effluxer present in organs that transport a variety of xenobiotics and by-products. Previous findings by our group demonstrated that this transporter is also present in the oocyte mitochondrial membrane and that its mutation led to abnormal mitochondrial homeostasis. Considering the importance of these organelles in the female gamete, we assessed the impact of MDR-1 dysfunction on mouse oocyte quality, with a particular focus on the meiotic spindle organization, aneuploidies, Ca2+ homeostasis, ATP production and mtDNA mutations. Our results demonstrate that young Mdr1a mutant mice produce oocytes characterized by lower quality, with a significant delay in the germinal vesicle to germinal vesicle breakdown transition, an increased percentage of symmetric divisions, chromosome misalignments and a severely altered meiotic spindle shape compared to the wild types. Mutant oocytes exhibit 7000 more SNPs in the exomic DNA and twice the amount of mitochondrial DNA (mtDNA) SNPs compared to the wild-type ones. Ca2+ analysis revealed the inability of MDR-1 mutant oocytes to manage Ca2+ storage content and oscillations in response to several stimuli, and ATP quantification shows that mutant oocytes trend toward lower ATP levels compared to wild types. Finally, 1-year-old mutant ovaries express a lower amount of SIRT1, SIRT3, SIRT5, SIRT6 and SIRT7 compared to wild-type levels. These results together emphasize the importance of MDR-1 in mitochondrial physiology and highlight the influence of MDR-1 on oocyte quality and ovarian aging.

Comparison of detection methods and genome quality when quantifying nuclear mitochondrial insertions in vertebrate genomes.

The integration of mitochondrial genome fragments into the nuclear genome is well documented, and the transfer of these mitochondrial nuclear pseudogenes (numts) is thought to be an ongoing evolutionary process. With the increasing number of eukaryotic genomes available, genome-wide distributions of numts are often surveyed. However, inconsistencies in genome quality can reduce the accuracy of numt estimates, and methods used for identification can be complicated by the diverse sizes and ages of numts. Numts have been previously characterized in rodent genomes and it was postulated that they might be more prevalent in a group of voles with rapidly evolving karyotypes. Here, we examine 37 rodent genomes, and an additional 26 vertebrate genomes, while also considering numt detection methods. We identify numts using DNA:DNA and protein:translated-DNA similarity searches and compare numt distributions among rodent and vertebrate taxa to assess whether some groups are more susceptible to transfer. A combination of protein sequence comparisons (protein:translated-DNA) and BLASTN genomic DNA searches detect 50% more numts than genomic DNA:DNA searches alone. In addition, higher-quality RefSeq genomes produce lower estimates of numts than GenBank genomes, suggesting that lower quality genome assemblies can overestimate numts abundance. Phylogenetic analysis shows that mitochondrial transfers are not associated with karyotypic diversity among rodents. Surprisingly, we did not find a strong correlation between numt counts and genome size. Estimates using DNA: DNA analyses can underestimate the amount of mitochondrial DNA that is transferred to the nucleus.

Structural and Dynamic Features of Liver Mitochondria and Mitophagy in Rats with Hyperthyroidism.

This work investigated the effect of thyroxine on the biogenesis and quality control system of rat liver mitochondria. Chronic administration of thyroxine to experimental animals induced hyperthyroidism, which was confirmed by a severalfold increase in serum-free triiodothyronine and thyroxine concentrations. The uptake of oxygen was found to increase with a decrease in ADP phosphorylation efficiency and respiratory state ratio. Electron microscopy showed 36% of liver mitochondria to be swollen and approximately 18% to have a lysed matrix with a reduced number of cristae. Frequently encountered multilamellar bodies associated with defective mitochondria were located either at the edge of or inside the organelle. The number, area and perimeter of hyperthyroid rat mitochondria increased. Administration of thyroxine increased mitochondrial biogenesis and the quantity of mitochondrial DNA in liver tissue. Mitochondrial dynamics and mitophagy changed significantly. The data obtained indicate that excess thyroid hormones cause a disturbance of the mitochondrial quality control system and ultimately to the incorporation of potentially toxic material in the mitochondrial pool.

Histone deacetylase (HDAC) inhibitor curcumin upregulates mitochondrial uncoupling protein1 (UCP1) and mitochondrial function in brown adipocytes, in-silico study and screening natural drug library

Mitochondrial dysfunction has been associated with diverse pathological conditions globally. Specifically, in adipose tissues, mitochondrial dysfunction is the primary cause of obesity and obesity-related illnesses. An existing drugs such as atorvastatin and other lipid-lowering drugs demonstrated adverse effects and initiated other diseases. Thus, we need to explore new methods to prevent and treat obesity. In this study, we used the cell screening method to identify several natural compounds that increase adipocyte UCP1 gene expression. The identified drug Curcumin was evaluated in cell models and the In-silico model. We found curcumin is an active compound of turmeric belonging to Zingiberaceae (ginger family), which activates the Nrf2 mechanism. Curcumin potentially endorses the expression of UCP1 in the brown adipocyte in vitro cellular model. Curcumin plays an important role that modulating mitochondrial function and improving mitochondrial DNA quantification, ATP production, and cell viability. We have established an efficient in vitro cell experiment system to study the metabolic regulation of UCP1. The in-silico model revealed curcumin-UCP1 interaction. Curcumin, via enhancing mitochondrial activity, could be a helpful therapeutic molecule against metabolic disorders or obesity-related diseases. Curcumin will be the subject of more research in both human and murine models, which will provide novel therapeutic pathways for the treatment of metabolic illnesses by modulating the control of mitochondrial function.

Mitochondrial dysfunction: The pathological link between psoriasis and insulin resistance?

Psoriasis is strongly associated with insulin resistance (IR). Lipid profile disturbances and upregulation of enzymes crucial for fatty acid oxidation have been reported in patients with psoriasis. Mitochondrial ß-oxidation is altered in patients with IR. Common mitochondrial dysfunction may be involved in the origin of both diseases. This study aimed to evaluate mitochondrial ß-oxidation, intermediary metabolism, and mitochondrial content in psoriatic patients with or without IR and compare them to healthy controls. The participants were divided into three groups: (1) psoriasis and IR (n=26); (2) psoriasis without IR (n=17); and (3) healthy controls (n=17). Quantification of amino acids and acylcarnitines (AC) by tandem mass spectrometry, determination of urinary organic acids by gas chromatography/mass spectrometry (GC/MS), and mitochondrial DNA quantification were performed in all groups. When comparisons were made between the two psoriatic groups, no differences were found between: C5DC + C6OH, C16:1, Met/Leu, Met/Phe, C16:1/C16, and C5DC + C6OH/C4DC + C5OH ratios. Nine analytes were different: phenylalanine, Cit/Phe, and Cit/Tyr ratios, C0, C3, C5, C6DC, C16, and C18:1OH. There were no correlations between psoriasis area and severity index (PASI), body mass index (BMI) and duration of disease with ACs. A higher proportion of patients with psoriasis showed increased urine levels of uric acid and hippuric acid (p=0.01). The mtDNA content was significantly higher in cases than in controls, with no differences between IR and non-IR psoriatic patients. Psoriasis patients with and without IR have a different acylcarnitine profile reflecting impaired ß-oxidation. A distinctive profile of acylcarnitines suggests an involvement of mitochondrial function associated with an increase in stearoyl CoA desaturase (SCD) activity in psoriatic patients with and without IR.

Baicalein modulates mitochondrial function by upregulating mitochondrial uncoupling protein-1 (UCP1) expression in brown adipocytes, cytotoxicity, and computational studies

BackgroundObesity, fatty liver, type 2 diabetes, and Non-alcoholic fatty liver disease (NAFLD) are all metabolic diseases caused by excess food consumption. Existing drug molecules had negative side effects and caused other diseases to develop (Orlistat causes angioedema, and menstrual irregularities; megestrol acetate causes hypertension, and insomnia). By enhancing lipid consumption and increasing nonshivering thermogenesis, targeting mitochondrial uncoupling protein-1 (UCP1) expression in adipocytes could be an auspicious treatment strategy against obesity or metabolic disorders associated with obesity. MethodsWe used previously produced UCP1-A-GFP reporter cell lines in this investigation to find new pharmacological compounds against obesity or metabolic syndrome, which we then tested in cellular analysis, cytotoxicity, mitochondrial function, mitochondrial DNA quantification, mitochondrial ATP production, and in-silico models. ResultsBaicalein was discovered to play a critical role in obesity prevention via altering mitochondrial function. Baicalein lowers ATP generation while increasing considerable UCP1 gene expression in brown adipocytes. As a result, cellular thermogenesis is boosted. The HEK293T cell line is harmless by baicalein. The investigation by the in-silico study revealed drug-protein interaction and UCP1 binding. Thus, our research clarifies baicalein's therapeutic role in metabolic and obesity-related illnesses via modulating mitochondrial activity (Supplementary Fig. 2). ConclusionsFurther studies are required in both murine and human models to understand the full mechanism of action by mitochondrial modulation. Drug development investigation also requires to development of a precise formulation.

Independent regulation of mitochondrial DNA quantity and quality in Caenorhabditis elegans primordial germ cells.

Mitochondria harbor an independent genome, called mitochondrial DNA (mtDNA), which contains essential metabolic genes. Although mtDNA mutations occur at high frequency, they are inherited infrequently, indicating that germline mechanisms limit their accumulation. To determine how germline mtDNA is regulated, we examined the control of mtDNA quantity and quality in C. elegans primordial germ cells (PGCs). We show that PGCs combine strategies to generate a low point in mtDNA number by segregating mitochondria into lobe-like protrusions that are cannibalized by adjacent cells, and by concurrently eliminating mitochondria through autophagy, reducing overall mtDNA content twofold. As PGCs exit quiescence and divide, mtDNAs replicate to maintain a set point of ~200 mtDNAs per germline stem cell. Whereas cannibalism and autophagy eliminate mtDNAs stochastically, we show that the kinase PTEN-induced kinase 1 (PINK1), operating independently of Parkin and autophagy, preferentially reduces the fraction of mutant mtDNAs. Thus, PGCs employ parallel mechanisms to control both the quantity and quality of the founding population of germline mtDNAs.

Cell-free mitochondrial DNA deletions in idiopathic, but not LRRK2, Parkinson's disease

Mitochondrial dysfunction happens in both idiopathic (iPD) and LRRK2-related Parkinson's disease (LRRK2-PD). Nonetheless, previous studies suggested that a different type of mitochondrial pathology underlies the neurodegeneration in these two disorders. To further explore this hypothesis, we developed a novel multiplex digital PCR assay that allows the absolute quantification of cell-free mitochondrial DNA (cf-mtDNA) copy number and deletion ratio directly in cerebrospinal fluid (CSF) by simultaneously measuring two opposed regions of the mtDNA circular molecule, one of them in the commonly deleted major arc. The results confirmed that the content of cf-mtDNA in CSF was statistically significantly different between iPD and LRRK2-PD patients. Moreover, we found high cf-mtDNA deletion levels in CSF from patients with iPD, but not LRRK2-PD. The high cf-mtDNA deletion frequency in iPD was validated in an independent cohort. These results indicated that the content and deletion ratio of cf-mtDNA may differentiate iPD from LRRK2-PD, and provides further evidence of the different mitochondrial pathophysiology between these two forms of the disease.

Anticancer Properties of Plectranthus ornatus-Derived Phytochemicals Inducing Apoptosis via Mitochondrial Pathway.

Since cancer treatment by radio- and chemotherapy has been linked to safety concerns, there is a need for new and alternative anticancer drugs; as such, compounds isolated from plants represent promising candidates. The current study investigates the anticancer features of halimane (11R*,13E)-11-acetoxyhalima-5,13-dien-15-oic acid (HAL) and the labdane diterpenes 1α,6β-diacetoxy-8α,13R*-epoxy-14-labden-11-one (PLEC) and forskolin-like 1:1 mixture of 1,6-di-O-acetylforskolin and 1,6-di-O-acetyl-9-deoxyforskolin (MRC) isolated from Plectranthus ornatus in MCF7 and FaDu cancer cell lines. Cytotoxicity was assessed by MTT assay, ROS production by Di-chloro-dihydro-fluorescein diacetate assay (DCFH) or Red Mitochondrial Superoxide Indicator (MitoSOX) and Mitochondrial Membrane Potential (MMP) by fluorescent probe JC-1 (5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide). In addition, the relative amounts of mitochondrial DNA (mtDNA) were determined using quantitative Real-Time-PCR (qRT-PCR) and damage to mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) by semi-long run quantitative Real-Time-PCR (SLR-qRT-PCR). Gene expression was determined using Reverse-Transcription-qPCR. Caspase-3/7 activity by fluorescence was assessed. Assessment of General In Vivo Toxicity has been determined by Brine Shrimp Lethality Bioassay. The studied HAL and PLEC were found to have a cytotoxic effect in MCF7 with IC50 = 13.61 µg/mL and IC50 = 17.49 µg/mL and in FaDu with IC50 = 15.12 µg/mL and IC50 = 32.66 µg/mL cancer cell lines. In the two tested cancer cell lines, the phytochemicals increased ROS production and mitochondrial damage in the ND1 and ND5 gene regions and reduced MMP (ΔΨm) and mitochondrial copy numbers. They also changed the expression of pro- and anti-apoptotic genes (Bax, Bcl-2, TP53, Cas-3, Cas-8, Cas-9, Apaf-1 and MCL-1). Studies demonstrated increase in caspase 3/7 activity in tested cancer cell lines. In addition, we showed no toxic effect in in vivo test for the compounds tested. The potential mechanism of action may have been associated with the induction of apoptosis in MCF7 and FaDu cancer cells via the mitochondrial pathway; however, further in vivo research is needed to understand the mechanisms of action and potential of these compounds.

Assessment of mitochondrial DNA viability ratio in day-4 biopsied embryos as an add-in to select euploid embryos for single embryo transfer.

The aim of this study was to assess mitochondrial DNA analysis as a predictor of the pregnancy potential of biopsied preimplantation embryos. The study included 78 blastomeres biopsied from day 4 cleavage stage euploid embryos. The embryo karyotype was confirmed by 24-chromosome preimplantation genetic testing for aneuploidies using the Illumina Next-Generation Sequencing (NGS) system. Mitochondria viability ratios (mtV) were determined from BAM files subjected to the web-based genome-analysis tool Galaxy. From this cohort of patients, 30.4% of patients (n = 34) failed to establish pregnancy. The mean mtV ratio [mean = 1.51 ± 1.25-1.77 (95% CI)] for this group was significantly (P < 0.01) lower compared with the embryo population that resulted in established pregnancies [mean = 2.5 ± 1.82-2.68 (95% CI)]. mtV multiple of mean (MoM) values were similarly significantly (P < 0.01) lower in blastocysts failing to establish pregnancy. At a 0.5 MoM cut-off, the sensitivity of mtV quantitation was 35.3% and specificity was 78.2%. The positive predictive value for an mtV value > 0.5 MoM was 41.4%. This study demonstrates the clinical utility of preimplantation quantification of viable mitochondrial DNA in biopsied blastomeres as a prognosticator of pregnancy potential.

Evidence of a role for cAMP in mitochondrial regulation in ovarian granulosa cells.

In the ovary, proliferation and differentiation of granulosa cells (GCs) drive follicular growth. Our immunohistochemical study in a non-human primate, the Rhesus monkey, showed that the mitochondrial activity marker protein cytochrome c oxidase subunit 4 (COX4) increases in GCs in parallel to follicle size, and furthermore, its intracellular localization changes. This suggested that there is mitochondrial biogenesis and trafficking, and implicates the actions of gonadotropins, which regulate follicular growth and ovulation. Human KGN cells, i.e. granulosa tumour cells, were therefore used to study these possibilities. To robustly elevate cAMP, and thereby mimic the actions of gonadotropins, we used forskolin (FSK). FSK increased the cell size and the amount of mitochondrial DNA of KGN cells within 24 h. As revealed by MitoTracker™ experiments and ultrastructural 3D reconstruction, FSK treatment induced the formation of elaborate mitochondrial networks. H89, a protein kinase A (PKA) inhibitor, reduced the network formation. A proteomic analysis indicated that FSK elevated the levels of regulators of the cytoskeleton, among others (data available via ProteomeXchange with identifier PXD032160). The steroidogenic enzyme CYP11A1 (Cytochrome P450 Family 11 Subfamily A Member 1), located in mitochondria, was more than 3-fold increased by FSK, implying that the cAMP/PKA-associated structural changes occur in parallel with the acquisition of steroidogenic competence of mitochondria in KGN cells. In summary, the observations show increases in mitochondria and suggest intracellular trafficking of mitochondria in GCs during follicular growth, and indicate that they may partially be under the control of gonadotropins and cAMP. In line with this, increased cAMP in KGN cells profoundly affected mitochondrial dynamics in a PKA-dependent manner and implicated cytoskeletal changes.

Cell-free mitochondrial DNA quantification in ischemic stroke patients for non-invasive and real-time monitoring of disease status

Cell-free mitochondrial DNA quantification in ischemic stroke patients for non-invasive and real-time monitoring of disease status

Energy Metabolism and Lipidome Are Highly Regulated during Osteogenic Differentiation of Dental Follicle Cells.

Dental follicle cells (DFCs) are stem/progenitor cells of the periodontium and give rise to alveolar osteoblasts. However, understanding of the molecular mechanisms of osteogenic differentiation, which is required for cell-based therapies, is delimited. This study is aimed at analyzing the energy metabolism during the osteogenic differentiation of DFCs. Human DFCs were cultured, and osteogenic differentiation was induced by either dexamethasone or bone morphogenetic protein 2 (BMP2). Previous microarray data were reanalyzed to examine pathways that are regulated after osteogenic induction. Expression and activity of metabolic markers were evaluated by western blot analysis and specific assays, relative amount of mitochondrial DNA was measured by real-time quantitative polymerase chain reaction, the oxidative state of cells was determined by a glutathione assay, and the lipidome of cells was analyzed via mass spectrometry (MS). Moreover, osteogenic markers were analyzed after the inhibition of fatty acid synthesis by 5-(tetradecyloxy)-2-furoic acid or C75. Pathway enrichment analysis of microarray data revealed that carbon metabolism was amongst the top regulated pathways after osteogenic induction in DFCs. Further analysis showed that enzymes involved in glycolysis, citric acid cycle, mitochondrial activity, and lipid metabolism are differentially expressed during differentiation, with most markers upregulated and more markedly after induction with dexamethasone compared to BMP2. Moreover, the cellular state was more oxidized, and mitochondrial DNA was distinctly upregulated during the second half of differentiation. Besides, MS of the lipidome revealed higher lipid concentrations after osteogenic induction, with a preference for species with lower numbers of C-atoms and double bonds, which indicates a de novo synthesis of lipids. Concordantly, inhibition of fatty acid synthesis impeded the osteogenic differentiation of DFCs. This study demonstrates that energy metabolism is highly regulated during osteogenic differentiation of DFCs including changes in the lipidome suggesting enhanced de novo synthesis of lipids, which are required for the differentiation process.

P422: OMIPALISIB, A DUAL PI3K/MTOR INHIBITOR, TARGETS MITOCHONDRIA AND IMPAIRS OXIDATIVE PHOSPHORYLATION IN ACUTE MYELOID LEUKEMIA

Background: Mitochondria play a central role in cell metabolism. Recent studies explored mitochondrial alterations contributing to metabolic vulnerability in myeloid leukemia cells may considered as therapeutic targets. We previously reported that omipalisib, a PI3K/mTOR dual inhibitor, could significantly inhibit the growth of myeloid leukemia cells and impair their mitochondrial respiration. However, the precise mechanism of the mitochondria dysfunction in response to omipalisib is still not fully studied. Aims: To explore the mechanism of the mitochondria dysfunction in response to omipalisib. Methods: OCI-AML3 and THP-1 myeloid leukemia cell lines were used in this study. Omipalisib (GSK2126458) and another PI3K/mTOR dual inhibitor gedatolisib (PF-05212384) were used. Flow cytometry was used for mitochondrial analysis. RNA-seq was performed by using an Illumina NovaSeq 6000 platform. Differentially expressed genes (DEGs) between control and omipalisib (or gedatolisib) were identified by EBseq with a threshold of p ≤ 0.05. The mRNA, nuclear and mitochondrial DNA quantification were measured by using QuantStudio 3 Real-Time PCR Systems. The parameters of mitochondrial respiration were analyzed by using the XFe 24 extracellular flux analyzer. Results: We demonstrated the anti-proliferative effect of omipalisib and gedatolisib on a panel of AML cell lines with different genetic backgrounds. OCI-AML3 cell lines had significant response to omipalisib and gedatolisib with IC50 of 17.45 nM and 153.38 nM, respectively. Subsequently, the transcriptome analysis of 50 nM omipalisib or 200 nM gedatolisib-treated OCI-AML3 cells were analyzed. Compared to DMSO-treated, a total of 1199 (595 upregulated and 604 downregulated) and 326 (218 upregulated and 108 downregulated) DEGs were identified in the omipalisib-treated cells and the gedatolisib-treated cells, respectively. Gene set enrichment analysis (GSEA) indicated that both omipalisib and gedatolisib could suppress “E2F targets”, “Myc targets”, and “G2M checkpoint”, and trigger “TNFα signaling via NFκB”, and “Inflammatory response”. Of them, we found that omipalisib had more significant effect to inhibit “Oxidative phosphorylation” (NES: -2.01) than gedatolisib did (NES: -1.40), especially mitochondrial biogenesis and amino acid metabolism-related pathways. Omipalisib had an inhibitory effect on the mitochondrial basal respiration rate and maximal respiration. Further analysis revealed quantitative reverse-transcription PCR analysis revealed that both omipalisib and gedatolisib could potently suppress serine synthesis (PHGDH, PSAT1, PSPH), glycine synthesis (SHMT1/2), and tetrahydrofolate cycle-related genes (MTHFD1/2) at the transcriptional level. On the other hand, rather than gedatolisib, omipalisib could significantly inhibit expression of glycolysis-related genes (GLUT1, HK2, PKM2, and LDHA) as well as mitochondrial biogenesis-related genes (PPARGC1B, TFAM, and NDUFS6). In addition, omipalisib could strongly decrease mtDNA and mitochondrial mass. These results suggest that omipalisib could suppress the mitochondrial biogenesis through alternative mechanisms, including but not limited to PI3K-AKT-mTOR signaling. Summary/Conclusion: Rather than gedatolisib, omipalisib could significantly inhibit mitochondrial biogenesis and suppress the respiration of mitochondria in myeloid leukemia cells. Our results indicate that omipalisib could suppress cell proliferation not only through PI3K-AKT-mTOR signaling but also via impairing mitochondrial biogenesis. This information may be potentially suitable for future clinical applications.

Bothrops lanceolatus snake venom impairs mitochondrial respiration and induces DNA release in human heart preparation.

Envenomations by Bothrops snakebites can induce overwhelming systemic inflammation ultimately leading to multiple organ system failure and death. Release of damage-associated molecular pattern molecules (DAMPs), in particular of mitochondrial origin, has been implicated in the pathophysiology of the deregulated innate immune response. To test whether whole Bothrops lanceolatus venom would induce mitochondrial dysfunction and DAMPs release in human heart preparations. Human atrial trabeculae were obtained during cannulation for cardiopulmonary bypass from patients who were undergoing routine coronary artery bypass surgery. Cardiac fibers were incubated with vehicle and whole Bothrops lanceolatus venom for 24hr before high-resolution respirometry, mitochondrial membrane permeability evaluation and quantification of mitochondrial DNA. Compared with vehicle, incubation of human cardiac muscle with whole Bothrops lanceolatus venom for 24hr impaired respiratory control ratio and mitochondrial membrane permeability. Levels of mitochondrial DNA increased in the medium of cardiac cell preparation incubated with venom of Bothrops lanceolatus. Our study suggests that whole venom of Bothrops lanceolatus impairs mitochondrial oxidative phosphorylation capacity and increases mitochondrial membrane permeability. Cardiac mitochondrial dysfunction associated with mitochondrial DAMPs release may alter myocardium function and engage the innate immune response, which may both participate to the cardiotoxicity occurring in patients with severe envenomation.