Mitochondrial DNA Damage Research Articles

Mechanisms underlying the inhibitory effects of linalool on Aspergillus flavus spore germination.

Biogenic volatile organic compounds hold remarkable potential for controlling fungal decay in agro- and food products. Recently, we reported that linalool, the major volatile component of the Zanthoxylum schinifolium pericarp, showed great potential as a biofumigant to control Aspergillus flavus growth in postharvest grains. In this study, the inhibitory effects of linalool on A. flavus growth in stored grains and its underlying mechanism were investigated through transcriptomic and biochemical analyses. Linalool vapor at 800 μL/L can effectively prevent A. flavus growth in 22% moisture wheat grains. Linalool at 2 μL/mL completely inhibited the germination of A. flavus spores, and 10 μL/mL caused spore death. Scanning electron microscopy revealed that linalool treatment caused wrinkling and spore breakage. Transcriptomics showed that 3806 genes were significantly differentially expressed in A. flavus spores exposed to 2 μL/mL linalool, predominantly showing enrichment regarding the ribosome, DNA replication, glutathione metabolism, peroxisome, and MAPK signaling pathways. Flow cytometry showed that linalool treatment caused hyperpolarization of mitochondrial membrane potential. 4,6-Diamidino-2-phenylindole staining indicated that linalool caused DNA fragmentation in A. flavus spores, and monodansylcadaverine staining confirmed that linalool induced autophagy in A. flavus spores. We thus propose that linalool can damage the plasma membrane, cause mitochondrial dysfunction and DNA damage, and induce autophagy in A. flavus spores. These findings considerably improve our understanding of the mechanisms underlying the inhibitory effects of linalool on A. flavus, which is crucial regarding the development of applications to prevent postharvest grain spoilage due to A. flavus infestations. KEY POINTS: • The inhibitory potency of linalool on A. flavus spore germination was determined. • Transcriptomic analyses were performed to identify differentially expressed genes of A. flavus exposed to linalool. • A functional mechanism underlying the inhibitory effects of linalool on A. flavus spore germination is proposed.

The emergent role of mitochondrial surveillance in cellular health.

Mitochondrial dysfunction is one of the primary causatives for many pathologies, including neurodegenerative diseases, cancer, metabolic disorders, and aging. Decline in mitochondrial functions leads to the loss of proteostasis, accumulation of ROS, and mitochondrial DNA damage, which further exacerbates mitochondrial deterioration in a vicious cycle. Surveillance mechanisms, in which mitochondrial functions are closely monitored for any sign of perturbations, exist to anticipate possible havoc within these multifunctional organelles with primitive origin. Various indicators of unhealthy mitochondria, including halted protein import, dissipated membrane potential, and increased loads of oxidative damage, are on the top of the lists for close monitoring. Recent research also indicates a possibility of reductive stress being monitored as part of a mitochondrial surveillance program. Upon detection of mitochondrial stress, multiple mitochondrial stress-responsive pathways are activated to promote the transcription of numerous nuclear genes to ameliorate mitochondrial damage and restore compromised cellular functions. Co-expression occurs through functionalization of transcription factors, allowing their binding to promoter elements to initiate transcription of target genes. This review provides a comprehensive summary of the intricacy of mitochondrial surveillance programs and highlights their roles in our cellular life. Ultimately, a better understanding of these surveillance mechanisms is expected to improve healthspan.

Circ_0002476 regulates cell growth, invasion, and mtDNA damage in non-small cell lung cancer by targeting miR-1182/TFAM axis.

BackgroundMany circular RNAs (circRNAs) have been identified as potential targets for cancer therapy. However, the role of circ_0002476 in non–small cell lung cancer (NSCLC) progression has not been explored.MethodsThe expression levels of circ_0002476, microRNA (miR)‐1182, and mitochondrial transcription factor A (TFAM) were detected by quantitative real‐time polymerase chain reaction. Cell functions were measured by cell counting kit 8 assay, EdU assay, colony formation assay, flow cytometry and transwell assay. Mitochondrial DNA (mtDNA) damage was assessed by measuring mtDNA copy number and transcript levels of ND1 and ATP6. Protein expression was examined by western blot. The interaction between miR‐1182 and circ_0002476 or TFAM was detected by dual‐luciferase reporter assay and RNA pull‐down assay. Animal experiments were performed to explore circ_0002476 role in vivo. Exosomes (Exs) were extracted and identified by transmission electron microscopy and nanoparticle tracking analysis.ResultsCirc_0002476 was overexpressed in NSCLC tissues and cells. Circ_0002476 knockdown suppressed NSCLC cell proliferation and invasion, while promoted apoptosis and mtDNA damage. Circ_0002476 could sponge miR‐1182, and miR‐1182 inhibitor reversed the influence induced by circ_0002476 knockdown. Moreover, TFAM was targeted by miR‐1182, and miR‐1182 hindered NSCLC cell progression by regulating TFAM. Additionally, circ_0002476 silencing could reduce NSCLC tumor growth by miR‐1182/TFAM. Further analyzed showed that Exs were involved in the transport of circ_0002476 between cells.ConclusionTaken together, our findings suggested that circ_0002476 might be a potential molecular target for NSCLC treatment.

Exposure of carbon nanotubes affects testis and brain of common carp

Carbon nanotubes production has been rapidly increasing for many potential applications, however, the environmental impact of this nanomaterial needs to be comprehended. The present work focused on unraveling the effects of single-walled carbon nanotubes (SWCNT) in the common carp, Cyprinus carpio. The physicochemical properties of SWCNT were analyzed with X-ray diffraction, Fourier transforms infra-red, UV-Vis absorption, transmission electron microscopy (TEM), and Raman spectroscopy before testing for exposure impact. The effects of SWCNT, were investigated by exposing to two doses viz., 10 and 50 μg/L, for 7 days in adult common carp, in vivo. Expression of key steroidogenic and transcription factor genes related to testis and brain were downregulated after the treatment. The concomitant decreases in serum testosterone and 11-ketotestosterone levels revealed the impact of SWCNT after exposure. Further, SWCNT exposure induced antioxidant enzymes namely glutathione-S-transferases, superoxide dismutase, and catalase in both testis and brain. Concurrently, histological and TEM analysis of testis revealed structural disarray. In addition, SWCNT treatment, in testicular and brain primary cell cultures decreased cell viability with an increase of reactive oxygen species levels, leading to a significant elevation of apoptotic cells. In line with this, low mitochondrial membrane potential and DNA damage were also observed during post SWCNT treatment. Taken together, transient exposure of SWCNT causes toxic effects and alters testicular and brain function in the common carp. Thus, the discharge of carbon nanotubes poses a greater risk to the aquatic environment warranting regulatory measures.

High-fat diet affects autophagy and mitochondrial compartment in rat Harderiangland.

The Harderian gland (HG) of Rattus norvegicus is an orbital gland secreting lipids that accumulate in excess under condition of increased lipid metabolism. To study the response elicitated by lipid overload in rat HG, we housed the animals in thermoneutral conditions (28-30°C) in association to high fat diet (HFD). In HFD rats alterated blood lipid levels result in lipid accumulation in HG as demonstrated by the increased gland weight and histochemical/ultrastructural analyses. The HFD-caused oxidative stress forces the gland to trigger antioxidant defense mechanisms and autophagic process, such as lipophagy and mitophagy. Induction of mitochondrial DNA(mtDNA) damage and repair was stronger in HFD-rat HGs. An increase in marker expression levels of mitochondrial biogenesis, fission, and fusion occurred to counteract mtDNA copy number reduction and mitophagy. Therefore, the results demonstrate that rat HG activates autophagy as survival strategy under conditions of increased lipid metabolism and suggest a key role for mitophagy and membrane dynamics in the mitochondrial adaptive response to HFD.

Redox-Activatable Theranostic Co-Prodrug for Precise Tumor Diagnosis and Selective Combination Chemotherapy.

A novel theranostic co-prodrug SCB has been designed by combining a co-prodrug from CDDO-Me and SAHA with a biotin-coupled near-infrared (NIR) probe hemicyanine via redox-responsive linker thiolactate to enhance the tumor theranostic efficacy and reduce the toxic side effects using both active and passive targeting strategies. SCB displayed reactive oxygen species (ROS)- and glutathione (GSH)-dependent release of NIR fluorescence and two parent drugs. Furthermore, the administration of SCB caused selective illumination of the tumor tissues for >24 h, thereby guiding precise removal of a tumor from intraoperative mice. Importantly, SCB exhibited highly efficient tumor inhibition, exerted selective combination therapy through prodrug mode, and minimized the adverse effects. Finally, SCB induced mitochondrial depolarization, DNA damage, and cell apoptosis through ROS generation and downregulation of HDAC6 protein, as verified by H2AX, Bax, cleaved-PARP, and Mcl-1 proteins. Thus, we suggest that SCB can provide a new platform for both precise diagnosis-guided tumor removal and selective combination therapy with high safety.

Targeting lactate dehydrogenase B-dependent mitochondrial metabolism affects tumor initiating cells and inhibits tumorigenesis of non-small cell lung cancer by inducing mtDNA damage

Once considered a waste product of anaerobic cellular metabolism, lactate has been identified as a critical regulator of tumorigenesis, maintenance, and progression. The putative primary function of lactate dehydrogenase B (LDHB) is to catalyze the conversion of lactate to pyruvate; however, its role in regulating metabolism during tumorigenesis is largely unknown. To determine whether LDHB plays a pivotal role in tumorigenesis, we performed 2D and 3D in vitro experiments, utilized a conventional xenograft tumor model, and developed a novel genetically engineered mouse model (GEMM) of non-small cell lung cancer (NSCLC), in which we combined an LDHB deletion allele with an inducible model of lung adenocarcinoma driven by the concomitant loss of p53 (also known as Trp53) and expression of oncogenic KRAS (G12D) (KP). Here, we show that epithelial-like, tumor-initiating NSCLC cells feature oxidative phosphorylation (OXPHOS) phenotype that is regulated by LDHB-mediated lactate metabolism. We show that silencing of LDHB induces persistent mitochondrial DNA damage, decreases mitochondrial respiratory complex activity and OXPHOS, resulting in reduced levels of mitochondria-dependent metabolites, e.g., TCA intermediates, amino acids, and nucleotides. Inhibition of LDHB dramatically reduced the survival of tumor-initiating cells and sphere formation in vitro, which can be partially restored by nucleotide supplementation. In addition, LDHB silencing reduced tumor initiation and growth of xenograft tumors. Furthermore, we report for the first time that homozygous deletion of LDHB significantly reduced lung tumorigenesis upon the concomitant loss of Tp53 and expression of oncogenic KRAS without considerably affecting the animal’s health status, thereby identifying LDHB as a potential target for NSCLC therapy. In conclusion, our study shows for the first time that LDHB is essential for the maintenance of mitochondrial metabolism, especially nucleotide metabolism, demonstrating that LDHB is crucial for the survival and proliferation of NSCLC tumor-initiating cells and tumorigenesis.

Proteomic Response of Aedes aegypti Larvae to Silver/Silver Chloride Nanoparticles Synthesized Using Bacillus thuringiensis subsp. israelensis Metabolites.

Silver/silver chloride nanoparticles (Ag/AgCl NPs) are an alternative approach to control the larvae of Aedes aegypti, a vector of mosquito-borne diseases. However, the molecular mechanisms of Ag/AgCl NPs to A. aegypti have not been reported. In this work, Ag/AgCl NPs were synthesized using supernatant, mixed toxins from Bacillus thuringiensis subsp. israelensis (Bti), and heterologously expressed Cry4Aa and Cry4Ba toxins. The images from scanning electron microscopy revealed that the Ag/AgCl NPs were spherical in shape with a size range of 25-100 nm. The larvicidal activity against A. aegypti larvae revealed that the Ag/AgCl NPs synthesized using the supernatant of Bti exhibited higher toxicity (LC50 = 0.133 μg/mL) than the Ag/AgCl NPs synthesized using insecticidal proteins (LC50 = 0.148-0.217 μg/mL). The proteomic response to Ag/AgCl NPs synthesized using the supernatant of Bti in A. aegypti larvae was compared to the ddH2O-treated control. Two-dimensional gel electrophoresis analysis revealed 110 differentially expressed proteins, of which 15 were selected for identification using mass spectrometry. Six upregulated proteins (myosin I heavy chain, heat shock protein 70, the F0F1-type ATP synthase beta subunit, methyltransferase, protein kinase, and condensin complex subunit 3) that responded to Ag/AgCl NP treatment in A. aegypti were reported for NP treatments in different organisms. These results suggested that possible mechanisms of action of Ag/AgCl NPs on A. aegypti larvae are: mitochondrial dysfunction, DNA and protein damage, inhibition of cell proliferation, and cell apoptosis. The findings from this work provide greater insight into the action of green synthesized Ag/AgCl NPs on the control of A. aegypti larvae.

Toxicity of pesticides widely applied on soybean cultivation: Synergistic effects of fipronil, glyphosate and imidacloprid in HepG2 cells

The transgenic soy monoculture demands supplementation with pesticides. The aim of this study was to evaluate the individual and mixture effects of fipronil, glyphosate and imidacloprid in human HepG2 cells. Cytotoxicity was evaluated after 48-h incubations through MTT reduction and neutral red uptake assays. Free radicals production, mitochondrial membrane potential, DNA damage, and release of liver enzymes were also evaluated. Data obtained for individual agents were used to compute the additivity expectations for two mixtures of definite composition (one equipotent mixture, based in the EC50 values achieved in the MTT assay; the other one based in the acceptable daily intake of each pesticide), using the models of concentration addition and independent action. The EC50 values for fipronil, glyphosate and imidacloprid were 37.59, 41.13, and 663.66 mg/L, respectively. The mixtures of pesticides elicited significant synergistic effects (p < 0.05), which were greater than the expected by both addictive predictions. Decreased in mitochondrial membrane potential and increased in the transaminases enzymatic activities were observed. As they occur simultaneously, interactions between pesticides, even at non-effective single levels, can reverberate in significant deleterious effects, justifying the need for a more realistic approach in safety evaluations to better predict the effects to human health.

Renoprotective potentials of small molecule natural products targeting mitochondrial dysfunction.

Kidney diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), have become critical clinical, socioeconomic, and public health concerns worldwide. The kidney requires a lot of energy, and mitochondria act as the central organelle for the proper functioning of the kidney. Mitochondrial dysfunction has been associated with the pathogenesis of AKI and CKD. Natural products and their structural analogs have been sought as an alternative therapeutic strategy despite the challenges in drug discovery. Many studies have shown that small-molecule natural products can improve renal function and ameliorate kidney disease progression. This review summarizes the nephroprotective effects of small-molecule natural products, such as berberine, betulinic acid, celastrol, curcumin, salidroside, polydatin, and resveratrol. Treatment with small-molecule natural products was shown to attenuate renal oxidative stress and mitochondrial DNA (mtDNA) damage and restore mitochondrial biogenesis and dynamics in the kidneys against various injury stimuli. Therefore, small-molecule natural products should be recognized as multi-target therapeutics and promising drugs to prevent kidney diseases, particularly those with mitochondrial dysfunction.

Role of Mitochondria in Retinal Pigment Epithelial Aging and Degeneration.

Retinal pigment epithelial (RPE) cells form a monolayer between the neuroretina and choroid. It has multiple important functions, including acting as outer blood-retina barrier, maintaining the function of neuroretina and photoreceptors, participating in the visual cycle and regulating retinal immune response. Due to high oxidative stress environment, RPE cells are vulnerable to dysfunction, cellular senescence, and cell death, which underlies RPE aging and age-related diseases, including age-related macular degeneration (AMD). Mitochondria are the powerhouse of cells and a major source of cellular reactive oxygen species (ROS) that contribute to mitochondrial DNA damage, cell death, senescence, and age-related diseases. Mitochondria also undergo dynamic changes including fission/fusion, biogenesis and mitophagy for quality control in response to stresses. The role of mitochondria, especially mitochondrial dynamics, in RPE aging and age-related diseases, is still unclear. In this review, we summarize the current understanding of mitochondrial function, biogenesis and especially dynamics such as morphological changes and mitophagy in RPE aging and age-related RPE diseases, as well as in the biological processes of RPE cellular senescence and cell death. We also discuss the current preclinical and clinical research efforts to prevent or treat RPE degeneration by restoring mitochondrial function and dynamics.

Mitochondrial Dysfunction and Chronic Liver Disease.

Mitochondria are generally considered the powerhouse of the cell, a small subcellular organelle that produces most of the cellular energy in the form of adenosine triphosphate (ATP). In addition, mitochondria are involved in various biological functions, such as biosynthesis, lipid metabolism, oxidative phosphorylation, cell signal transduction, and apoptosis. Mitochondrial dysfunction is manifested in different aspects, like increased mitochondrial reactive oxygen species (ROS), mitochondrial DNA (mtDNA) damage, adenosine triphosphate (ATP) synthesis disorder, abnormal mitophagy, as well as changes in mitochondrial morphology and structure. Mitochondrial dysfunction is related to the occurrence and development of various chronic liver diseases, including hepatocellular carcinoma (HCC), viral hepatitis, drug-induced liver injury (DILI), alcoholic fatty liver (AFL), and non-alcoholic fatty liver (NAFL). In this review, we summarize and discuss the role and mechanisms of mitochondrial dysfunction in chronic liver disease, focusing on and discussing some of the latest studies on mitochondria and chronic liver disease.

β-Hydroxyisovaleryl-Shikonin Exerts an Antitumor Effect on Pancreatic Cancer Through the PI3K/AKT Signaling Pathway.

Pancreatic cancer (PC) is marked with a low survival rate and lack of recognized effective treatment strategy. We investigated the antitumor effect of β-hydroxyisovaleryl-shikonin (β-HIVS) on PC and the associated working mechanism. Cell toxicity was determined using Cell Counting Kit-8 (CCK-8) assay. Acridine Orange/Ethidium Bromide (AO/EB) double-fluorescent staining assay accompanied by flow cytometry was utilized to estimate cell apoptosis. Cell cycle, reactive oxygen species (ROS), and mitochondrial membrane potential were all evaluated using flow cytometry. Transwell and wound healing assays were performed to evaluate cell migration and invasion. Protein expression was analyzed by Western blots. A xenograft mouse model was employed to determine the antitumor effect of β-HIVS in vivo. PC cell viability gradually decreased with increasing β-HIVS while apoptosis was enhanced together with cell-cycle blockage in the G0–G1 phases. β-HIVS induced mitochondrial dysfunction, ROS production, and DNA damage and inhibited the invasive and migratory ability of PC cells. We further confirmed the suppression of EMT and PI3K/AKT pathways as underlying mechanisms. The mouse model treated with the increasing dose of β-HIVS displayed decreased tumor growth rate, along with increased apoptosis. Thus, β-HIVS exerts antitumor effects on PC through inducing apoptosis, ROS production, decreasing mitochondrial membrane potential, and suppressing signal pathways, such as PI3K/AKT. In summary, β-HIVS might be a promising strategy for PC treatment.

Evaluation of antimicrobial, anticancer potential and Flippase induced leakage in model membrane of Centella asiatica fabricated MgONPs.

The use of chemically synthesized nanoparticles and crude plant extracts as antimicrobial -anticancer agents have many limitations. In this study, we have used Centella asiatica extract (CaE) having relatively less explored but tremendous medicinal properties, as reducing and stabilizing agents to green synthesize magnesium oxide nanoparticles (MgONPs) using magnesium nitrate. In comparison to the bulk material, capabilities of Ca-MgONPs as an improved antibacterial, antifungal, and anticancer agent in human prostatic carcinoma cells (PC3), as well as membranolytic capability in model cell membrane, were studied. The phyto-functionalized Ca-MgONPs were characterized using UV-Visible spectroscopy (UV-Vis), Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray Spectroscopy (EDX), X-ray Diffraction (XRD), Fourier Transform Infra-Red Spectroscopy (FT-IR) and Atomic Force Microscopy (AFM). Observation of characteristic peaks by spectroscopic and microscopic analysis confirmed the synthesis of Ca-MgONPs. The Ca-MgONPs showed broad spectrum of bactericidal activity against both gram-positive and gram-negative bacteria and fungicidal activity against two species of the Candida fungus. The Ca-MgONPs also exhibited dose-dependent and selective inhibition of proliferating PC3 cells with IC50 of 123.65±4.82μg/mL at 24h, however, without having any cytotoxicity toward non-cancerous HEK293 cells. Further studies aimed at understanding the probable mechanism of toxicity of Ca-MgONPs in PC3 cells, the results indicated a significant reduction in cell migration capacities, increment in cytosolic ROS, loss of mitochondrial transmembrane potential, DNA damage and S-phase cell cycle arrest. Ca-MgONPs also induced pore formation in a synthetic large unilamellar vesicle. Thus, Ca-MgONPs might be useful in the effective management of several human pathogens of concern and some more cancer types.

Study of the Antioxidant Effect of &lt;italic&gt;Ojayeonjong-hwan&lt;/italic&gt;

Objective: In this study, the antioxidant activity of &lt;i&gt;Ojayeonjong-hwan&lt;/i&gt; extracts was compared, and the following results were obtained.Methods: For hydrothermal and ethanol extracts, DPPH free radical and ABTS cationic radical erasing activity and reducing power using the FRAP method were compared, and the association between the antioxidant power of each extract and total phenol content was investigated. Significant results were obtained through in vitro apoptosis analysis through FFITC staining, mitochondrial membrane potential analysis, and ROS level measurement using C2C12 myoblastoma.Results: 1. In a comparison of DPPH free radical and ABTS cationic radical scavenging activity, water, and 70% ethanol extracts of &lt;i&gt;Ojayeonjong-hwan&lt;/i&gt; (WEO and EEO) showed superior radical scavenging ability. &lt;br/&gt;2. In the results of reducing power using the FRAP method, WEO and EEO showed antioxidant activity, which was shown to be dependent on the total phenol content contained in the extracts. &lt;br/&gt;3. In comparison to the protective effect against H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt;-induced oxidative stress in C2C12 myoblasts, water extracts had no significant effect, but 70% ethanol extracts inhibited H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt;-mediated cytotoxicity in a concentration-dependent manner. &lt;br/&gt;4. The cytotoxic protective effect of EEO against oxidative stress in C2C12 myoblasts was correlated with its inhibitory effects on H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt;-induced apoptosis and cell-cycle arrest. &lt;br/&gt;5. In H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt;-treated C2C12 myoblasts, the apoptosis inhibitory effects of EEO were associated with the suppression of mitochondrial dysfunction and DNA damage. &lt;br/&gt;6. The protective effects of EEO against H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt;-induced oxidative stress in C2C12 myoblasts were directly related to the inhibition of ROS generation.Conclusions: &lt;i&gt;Ojayeonjong-hwan&lt;/i&gt; extracts all have protective potential against oxidative stress.

P-154 growth hormone supplementation decline quality of maternally aged oocytes via reducing aneuploidy

Abstract Study question Does growth hormone (GH) supplementation ameliorate the quality of oocytes in aged mice via reducing aneuploidy? Summary answer Daily injections of growth hormone for 2 months improve the age-related decline in ovarian reserve, and promote oocyte quality by reducing the aneuploidy rate. What is known already Women of advanced maternal age, particular over 35 years, could consequently bear poor quality oocytes, which are mainly caused by chromosomal aneuploidy. Age-related decline in GH levels may be related to the insufficient reproductive potential in women of advanced maternal age. To date, the role of GH in in vitro fertilization remains controversial. GH has been reported to affect oocyte quality, and studies in vivo have shown that intraperitoneal administration of GH reduces the occurrence rate of spindle/chromosome defects. Study design, size, duration The young (6-week-old) and aged (8-month-old) C57BL/6J mice were used in the study. In the in vivo experiment, aged mice were intraperitoneally injected daily with GH (1.6 mg/kg body weight, n = 85) or the equivalent volume of NS (n = 81) for consecutive for two months. In the in vitro experiment, GV oocytes from aged mice were treated with GH (Gene Science Pharmaceuticals, Changchun, China) (200ng/ml) in M16 medium for 14∼16 hours. Participants/materials, setting, methods We analyzed the number of oocytes and hormone levels to assess ovarian reserve, by immunohistochemistry and ELISA methods. The expression of GHR was measured by real-time quantitative RT-PCR and immunofluorescence. Time–lapse incubator was utilized to record the developmental potential of oocytes and embryos. Immunofluorescence was performed to assess parameters of oocyte quality (mitochondrial functions, ROS level, spindle/chromosome defects, and DNA damage). Chromosome spread and single-cell DNA sequencing were used to analyze chromosome aneuploidy rate. Main results and the role of chance The expression of GHR decreased in aged oocyte (21.68±1.08) and increased after GH treatment(30.64±0.70, P &amp;lt; 0.001). GH ameliorated decline in ovarian reserve of aged mice, with increased ovarian index (0.040%±0.0031 vs 0.023%±0.0019, P &amp;lt; 0.01), number of preantral follicles (7.33±0.89 vs 4.12±0.58, P &amp;lt; 0.05) and antral follicles (8.67±1.2 vs 3.33±0.88, P &amp;lt; 0.05) compared to the aged controls, but no other hormonal differences were detected. After GH supplementation, aged oocyte showed better quality and developmental potential, including restored mitochondrial functions (P &amp;lt; 0.05) and decreased ROS level (19.83±1.50 vs 23.6±1.72, P &amp;lt; 0.05). As expected, GH effectively promoted the fertilization rate (39.9%±1.10 vs 14.4%±0.62, P &amp;lt; 0.001) and early embryo development (P &amp;lt; 0.01). In addition, the spindle/chromosome defects (31.6%±2.12 vs 48.9%±1.83, P &amp;lt; 0.01), DNA damage (16.37±1.76 vs 49.35±2.52, P &amp;lt; 0.001) and aneuploidy rate (21.5%±1.61 vs 34.6%±1.84, P &amp;lt; 0.01) were lower in GH group than that in control group. Overall, GH treatment restored age-related decline in ovarian reserve, and decreased the occurrence rate of aneuploidy caused by spindle/chromosome defects, inducing a better oocyte quality in aged mice. Limitations, reasons for caution The molecular and mechanism of GH to regulate spindle/chromosome function remains to be determined. Besides, future work should be extended to human oocyte to determine whether this mechanism is conserved between mice and humans. Wider implications of the findings Our work expounds a theoretical basis for application of GH to improve the fertility of aged women. Besides, the results also feed new ideas for the prevention and treatment of oocyte quality decline in assisted reproductive technology. Trial registration number not applicable

Modeling of mitochondrial bioenergetics and autophagy impairment in MELAS-mutant iPSC-derived retinal pigment epithelial cells

BackgroundMitochondrial dysfunction and mitochondrial DNA (mtDNA) damage in the retinal pigment epithelium (RPE) have been implicated in the pathogenesis of age-related macular degeneration (AMD). However, a deeper understanding is required to determine the contribution of mitochondrial dysfunction and impaired mitochondrial autophagy (mitophagy) to RPE damage and AMD pathobiology. In this study, we model the impact of a prototypical systemic mitochondrial defect, mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), in RPE health and homeostasis as an in vitro model for impaired mitochondrial bioenergetics.MethodsWe used induced pluripotent stem cells (iPSCs) derived from skin biopsies of MELAS patients (m.3243A > G tRNA leu mutation) with different levels of mtDNA heteroplasmy and differentiated them into RPE cells. Mitochondrial depletion of ARPE-19 cells (p0 cells) was also performed using 50 ng/mL ethidium bromide (EtBr) and 50 mg/ml uridine. Cell fusion of the human platelets with the p0 cells performed using polyethylene glycol (PEG)/suspension essential medium (SMEM) mixture to generate platelet/RPE “cybrids.” Confocal microscopy, FLowSight Imaging cytometry, and Seahorse XF Mito Stress test were used to analyze mitochondrial function. Western Blotting was used to analyze expression of autophagy and mitophagy proteins.ResultsWe found that MELAS iPSC-derived RPE cells exhibited key characteristics of native RPE. We observed heteroplasmy-dependent impairment of mitochondrial bioenergetics and reliance on glycolysis for generating energy in the MELAS iPSC-derived RPE. The degree of heteroplasmy was directly associated with increased activation of signal transducer and activator of transcription 3 (STAT3), reduced adenosine monophosphate-activated protein kinase α (AMPKα) activation, and decreased autophagic activity. In addition, impaired autophagy was associated with aberrant lysosomal function, and failure of mitochondrial recycling. The mitochondria-depleted p0 cells replicated the effects on autophagy impairment and aberrant STAT3/AMPKα signaling and showed reduced mitochondrial respiration, demonstrating phenotypic similarities between p0 and MELAS iPSC-derived RPE cells.ConclusionsOur studies demonstrate that the MELAS iPSC-derived disease models are powerful tools for dissecting the molecular mechanisms by which mitochondrial DNA alterations influence RPE function in aging and macular degeneration, and for testing novel therapeutics in patients harboring the MELAS genotype.

Ecklonia cava extracts decrease hypertension-related vascular calcification by modulating PGC-1α and SOD2

Vascular calcification (VC) is induced by a decrease in sirtuin 3 (SIRT3) and superoxide dismutase (SOD)2 and increases mitochondrial reactive oxygen species (mtROS), eventually leading to mitochondrial dysfunction and phenotype alterations in vascular smooth muscle cells (VSMCs) into osteoblast-like cells in hypertension. Ecklonia cava extract (ECE) is known to increase peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α) and SOD2. In this study, we evaluated the effect of ECE on decreasing VC by increasing PGC-1α which increased SOD2 activity and decreased mtROS in an in vitro VSMC model of treating serums from Wistar Kyoto (WKY), spontaneous hypertensive rats (SHRs), and ECE-treated SHRs. Furthermore, the decreasing effect of ECE on VC was evaluated with an in vivo SHR model. PGC-1α expression, SIRT3 expression, and SOD2 activity were decreased by the serum from the SHRs and increased by the serum from the ECE-treated SHRs in the VSMCs. PGC-1α silencing eliminated those increases. mtROS generation and mitochondrial DNA (mtDNA) damage increased in the SHRs but decreased with ECE. Mitochondrial fission increased in the SHRs but decreased by ECE. Mitochondrial fusion, mitophagy, and mitochondrial biogenesis were decreased in the SHRs but increased by ECE. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and calcium deposition in the medial layer of the aorta increased in the SHRs but decreased with ECE. Therefore, ECE decreases VC via the upregulation of PGC-1α and SIRT3, which increases SOD2 activity. Activated SOD2 decreases mtDNA damage and mtROS generation, which sequentially decreases NADPH oxidase activity and changes the mitochondrial dynamics, thereby decreasing VC.

Abstract 2316: Malignant potential of colorectal adenoma based on the telomere length

Abstract Telomere attrition is a well-known hallmark of malignancy in cancer tissue. Our study analyzed the relative telomere length in adenomas, precursor lesions of colorectal adenocarcinoma. We investigated if the accelerated telomere length shortening occurs before potential malignant transformation to adenocarcinoma and corresponds with clinicopathological characteristics. Relative telomere length was measured in 145 patients using multiplex qPCR. We have recorded significant shortening of telomeres in the adenoma tissue compared to adjacent mucosa (Wilcoxon Signed Rank test, p &amp;lt; 0.0001). Further, we have observed a weak inverse relationship between both adenoma and mucosa telomere length and age (Spearman's and Pearson's correlation, p = 0.021 and p = 0.027, respectively), contrary to our previous study of colorectal cancer patients (n = 696), where the inverse correlation of telomere length was detected only in the non-malignant mucosa (Pearson's correlation, p = 0.029). However, the telomere length ratio of adenoma to adjacent mucosa did not correspond with the degree of dysplasia according to the Vienna classification (Kruskal-Wallis test, p = 0.572). Also, there was no difference in the telomere length ratio among histological types of adenomas and no association with the adenoma localization in proximal and distal colon or rectum (Kruskal-Wallis test, p = 0.648 and p = 0.459, respectively). Preliminary results indicate that telomere shortening occurs indeed as early as in a stage of adenomatous polyps, and it is less pronounced in adenomas compared to cancerous cells. However, the relative telomere length does not seem to correspond with adenoma progression towards malignancy. In planned experiments, we intend to assess mitochondrial DNA damage caused by 8-oxoguanine DNA adducts. These major oxidative base lesions can arise from endogenous reactive oxygen species and impact, among other things, the integrity of telomeres through double-strand breaks to DNA. Mitochondrial DNA is more prone to accumulation of oxidative damage than nuclear DNA and thus might be useful as an early, additional indicator of the precancerous character of adenoma. The study will reveal whether increased mitochondrial DNA damage and telomere loss are commonly present and linked together in adenomas. This study was supported by the Charles University (project GA UK No. 120, UNCE/MED/006) and the Grant Agency of the Czech Republic (21-04607X, 21-27902S). Citation Format: Kristyna Tomasova, Michal Kroupa, Anna Siskova, Josef Horak, Ondrej Vycital, Vaclav Liska, Ludmila Vodickova, Pavel Vodicka. Malignant potential of colorectal adenoma based on the telomere length [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2316.

Signaling Pathways Related to Oxidative Stress in Diabetic Cardiomyopathy.

Diabetes is a chronic metabolic disease that is increasing in prevalence and causes many complications. Diabetic cardiomyopathy (DCM) is a complication of diabetes that is associated with high mortality, but it is not well defined. Nevertheless, it is generally accepted that DCM refers to a clinical disease that occurs in patients with diabetes and involves ventricular dysfunction, in the absence of other cardiovascular diseases, such as coronary atherosclerotic heart disease, hypertension, or valvular heart disease. However, it is currently uncertain whether the pathogenesis of DCM is directly attributable to metabolic dysfunction or secondary to diabetic microangiopathy. Oxidative stress (OS) is considered to be a key component of its pathogenesis. The production of reactive oxygen species (ROS) in cardiomyocytes is a vicious circle, resulting in further production of ROS, mitochondrial DNA damage, lipid peroxidation, and the post-translational modification of proteins, as well as inflammation, cardiac hypertrophy and fibrosis, ultimately leading to cell death and cardiac dysfunction. ROS have been shown to affect various signaling pathways involved in the development of DCM. For instance, OS causes metabolic disorders by affecting the regulation of PPARα, AMPK/mTOR, and SIRT3/FOXO3a. Furthermore, OS participates in inflammation mediated by the NF-κB pathway, NLRP3 inflammasome, and the TLR4 pathway. OS also promotes TGF-β-, Rho-ROCK-, and Notch-mediated cardiac remodeling, and is involved in the regulation of calcium homeostasis, which impairs ATP production and causes ROS overproduction. In this review, we summarize the signaling pathways that link OS to DCM, with the intention of identifying appropriate targets and new antioxidant therapies for DCM.